Reprinted with permission from The American Spinal Injury Association. Chicago: International standards for neurological and functional classification of spinal cord injury; 1996.
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The Agency for Healthcare Research and Quality (AHRQ), through its Evidence-based Practice Centers (EPCs), sponsors the development of evidence reports and technology assessments to assist public- and private-sector organizations in their efforts to improve the quality of health care in the United States. The reports and assessments provide organizations with comprehensive, science-based information on common, costly medical conditions and new health care technologies. The EPCs systematically review the relevant scientific literature on topics assigned to them by AHRQ and conduct additional analyses when appropriate prior to developing their reports and assessments.
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| John M. Eisenberg, M.D. | Robert Graham, M.D. | ||
| Director | Director, Center for Practice and | ||
| Agency for Healthcare Research and Quality | Technology Assessment | Agency for Healthcare Research and Quality |
| The authors of this report are responsible for its content. Statements in the report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services of a particular drug, device, test, treatment, or other clinical service. |
This report describes evidence on the respiratory management of persons with acute or chronic cervical level spinal cord injury (SCI), including mechanical ventilation and other interventions aimed at preventing or treating respiratory diseases.
Databases searched were MEDLINE (1966-Feb 2000), HealthSTAR (1975-Feb 2000), Cumulative Index to Nursing & Allied Health Literature (CINAHL) (1983-Feb 2000), and EMBASE (1980-Feb 2000). The search strategies included the MeSH terms spinal cord injuries, paraplegia, and quadriplegia [exploded] and text words for tetraplegia, quadriplegia, and paraplegia with a pulmonary disease concept. The search was limited to articles pertaining to humans and published in the English language.
The population of interest is adults with traumatic cervical SCI. Interventions considered include intubation and airway management, mechanical ventilation initiation, and weaning as well as medications (bronchodilators, mucolytics) and respiratory therapy (noninvasive positive pressure ventilation [NPPV], assisted cough, postural drainage, humidification, spirometry, vital capacity assessment). Evidence was considered from controlled or uncontrolled studies.
At least two reviewers independently screened titles and abstracts; references included by either rater were retained. Full reports were reevaluated according to the selection criteria and data describing study population, study design, interventions, and outcome data were recorded. Quality was assessed based on criteria related to external validity (characterization of the study population) and internal validity (strength of study design).
Patients with C4-level SCI have greater weaning success using progressive ventilatory-free breathing than synchronized intermittent mandatory ventilation techniques. In addition, high ventilator volume (more than 20 cc/kg) is associated with less atelectasis and faster weaning. Aggressive multimodal respiratory therapy interventions (including frequent turning, suctioning [and bronchial lavage], chest percussion and assisted coughing, inhaled bronchodilator treatments, deep breathing, and incentive spirometry) and rotating beds have been associated with reduced mortality, atelectasis, need for mechanical ventilation, or tracheostomy. Other secretion clearance modalities show evidence of improved cough (manual assisted cough, mechanical insufflator-exsufflator, glossopharyngeal breathing) but include no data on health outcomes. There is little evidence of an effect for other interventions, including active respiratory muscle exercise with incentive spirometry, inspiratory resistance training, and abdominal weight training.
Several alternatives to tracheostomy positive pressure ventilation (PPV) for long-term ventilatory support have been demonstrated, including electrophrenic respiration, noninvasive positive pressure ventilation, intermittent positive pressure breathing, pneumobelt, and glossopharyngeal breathing. Noninvasive ventilation may reduce the risk of pneumonia compared with tracheostomy PPV for patients requiring chronic ventilatory support.
Treatments aimed at improving ventilation, cough, and secretion clearance reduce atelectasis, pneumonia and the need for mechanical ventilation. Clinical research studies on pulmonary disease following cervical SCI cover only a small number of many important management decisions. Few studies use control groups (randomized or otherwise) or other designs to reduce bias.
This document is in the public domain and may be used and reprinted without permission except those copyrighted materials noted for which further reproduction is prohibited without the specific permission of copyright holders.
McCrory DC, Samsa GP, Hamilton BB, et al. Treatment of Pulmonary Disease Following Cervical Spinal Cord Injury. Evidence Report/Technology Assessment Number 27. (Prepared by the Duke Evidence-based Practice Center under Contract No. 290-97-0014.) AHRQ Publication No. 01-E014. Rockville, MD: Agency for Healthcare Research and Quality. September 2001.
The incidence of spinal cord injury (SCI) in the United States is approximately 10,000 new cases each year or 32 to 35 persons per million population. Because persons with SCI are surviving longer, the prevalence has been increasing and is now above 200,000 persons in the US. Despite being relatively uncommon, SCI is very expensive to treat incurring enormous costs for acute medical care, rehabilitation, medications and supplies, modification to home and vehicles, and personal assistance. SCI is the most expensive condition among all causes for hospitalization.
Injuries at the cervical level of the spinal cord, depending on the completeness of the lesion, can lead to tetraplegia, loss of sensory function, and paralysis of the respiratory muscles. Patients with paralyzed inspiratory muscles (principally the diaphragm) may not be able to breathe on their own and often must be placed on mechanical ventilators; patients with weak or paralyzed expiratory muscles (principally the abdominal and intercostal muscles) may have impaired ability to cough and clear mucoid secretions. The accumulation of retained secretions can lead to atelectasis and pneumonia.
Respiratory failure is the most common cause of death for patients with cervical injuries (particularly high-cervical injuries) during the acute phase of hospitalization, and one of the three most common causes of death subsequently; 30 percent during acute hospitalization and 20 percent subsequently. The rate of respiratory complications is highest in the weeks immediately following SCI; atelectasis and pneumonia are the most frequent respiratory complications.
This report assesses the evidence currently available on the prevention and treatment of pulmonary disease following traumatic cervical SCI. The report focuses on empirical studies relating to two research questions about (1) management of ventilatory insufficiency in acute and chronic phases, including weaning from mechanical ventilation (MV), management of secretions, atelectasis, and pulmonary infection, and (2) the prevention of late respiratory failure in patients with traumatic cervical SCI. Excluded from consideration were non-pulmonary complications of SCI and venous thromboembolism/pulmonary embolus. The report does not cover patients with SCIs occurring below the cervical level or respiratory muscle weakness caused by neuromuscular or other spinal cord diseases such as Guillain-Barré syndrome and polio.
The key questions addressed in the report are:
For persons with traumatic high cervical SCI who are at
high risk of respiratory failure or require ventilator
support, what are the best practices regarding ventilator
management?
Specifically,
What characteristics predict need for initiation of mechanical ventilation?
What characteristics predict success in weaning from mechanical ventilation?
What ventilator management techniques improve the ability to wean from MV?
What are safe and effective techniques for intubation and airway management?
What are ventilator management techniques that can preserve lung compliance, prevent atelectasis, reduce the risk of complications?
For persons with traumatic cervical SCI who breathe on their own, what interventions -- including medications (bronchodilators, mucolytics) and prophylactic respiratory therapy (noninvasive positive pressure ventilation [NPPV], assisted cough, postural drainage, humidification, spirometry, vital capacity [VC] assessment) -- are effective to reduce the risk of late respiratory failure?
We focused on patients with acute traumatic cervical SCI, regardless of the degree of completeness of injury. We are interested in treatment in the days to months following acute injury and also the long-term followup over years.
Databases searched for literature were MEDLINE (1966-Feb 2000), HealthSTAR (1975-Feb 2000), Cumulative Index to Nursing & Allied Health Literature (CINAHL) (1983-Feb 2000), and EMBASE (1980-Feb 2000). The search strategies combined an SCI concept (implemented using MeSH terms spinal cord injuries, paraplegia, and quadriplegia [exploded] and text words for tetraplegia, quadriplegia, and paraplegia) with a pulmonary disease concept. The search was limited to articles pertaining to humans and published in the English language.
Empirical studies or review articles were included after screening by the following criteria: (1) the study population includes traumatic cervical SCI; (2) study question relates to the research questions described above; (3) study includes data on health outcomes, health services utilization or economic outcomes, or physiological measures related to respiratory status; (4) study design is controlled trial, prospective trial with historical controls, prospective or retrospective cohort study, or medium- to large-sized (more than 20 subjects) case series.
Each article was independently reviewed by at least two investigators.
Patients with cervical SCI are at significant risk for ventilatory failure, and this risk differs by the level and completeness of injury. Ventilatory support is needed for a majority of patients with C5 and higher injuries and virtually all patients with C3 and higher injuries in the acute phase. Patients with lower-cervical SCI are less likely to require mechanical ventilation (MV), as are those patients with greater forced vital capacity (FVC) on presentation. The amount of secretions and serious pulmonary infection (pneumonia) are associated with the need for MV. This finding suggests that treatments aimed at improving ventilation, cough, and secretion clearance may reduce the need for MV.
MV for ventilatory failure is usually performed using invasive (endotracheal or nasotracheal) intubation. However, NPPV can be successful for short- and long-term ventilatory assistance when used properly, particularly when patients have spontaneous FVC approaching 1 liter. In patients with C4 level of injury (LOI), weaning from MV is often a protracted process that is sometimes not successful. However, patients with C4-level SCI appear to have greater success when weaned by progressive ventilatory-free breathing than by synchronized intermittent mandatory ventilation techniques, which are more commonly used in patients with other causes for ventilatory failure. Furthermore, high ventilator volume (more than 20 cc/kg) is associated with less atelectasis and faster weaning.
Evidence is available on a variety of therapeutic and clinical assessment strategies among patients with traumatic tetraplegia, including the following:
Active respiratory muscle exercise with incentive spirometry, inspiratory resistance training, and abdominal weight training have all been associated with improvements in spontaneous vital capacity (VC) in prospective case series. However, in small randomized controlled trials (RCTs) these techniques have not been shown to improve ventilation, nor have the trials shown any difference between inspiratory resistance training and abdominal weight training.
Deflating cuffed tracheostomies or switching to cuffless tracheostomies is necessary to permit speech, but can cause hypocapnia as a result of increasing tidal volume to compensate for variable upper-airway leak. Adding dead space can increase pCO2 to near-normal levels, reducing hypocapnia during waking and sleeping periods. Speech valves are available to permit better speech.
Electrophrenic respiration has been successfully used for chronic ventilatory support, most often for part-time ventilatory support. Technological advances in recent years appear to have improved the success of the technique, but reliability remains an important problem.
The pneumobelt may be used for part-time ventilatory support or as an adjunct to full-time non-invasive ventilatory support.
Noninvasive ventilation may reduce the risk of pneumonia compared with tracheostomy positive pressure ventilation for patients requiring chronic ventilatory support. This technique may also prevent the need for invasive ventilation in patients with acute ventilatory insufficiency.
Glossopharyngeal breathing training can allow patients ventilator-free breathing for short periods and improve the effectiveness of cough and audibility of their voices.
Cough is improved with manual assisted cough by 15 to 33 percent in two studies. Positive pressure insufflation can improve cough as well. These techniques used together provided near-normal cough peak flows. Although abdominal binding (corset) did not improve spontaneous cough when used alone, when used in conjunction with manual assisted cough, positive pressure insufflation, or both, a trend toward improvement was suggested by one study. It follows that cough can also be improved by mechanical insufflation-exsufflation, as this technique provides 10 liters/second of expiratory flow.
Rotating beds have been associated with lower rates of pulmonary complications compared with less frequent turning with a wedge turning device in patients with cervical SCI in retrospective case series.
Aggressive multimodal respiratory therapy interventions (including frequent turning, suctioning [and bronchial lavage], chest percussion and assisted coughing, inhaled bronchodilator treatments, deep breathing, and incentive spirometry) have been associated with improvements in atelectasis in a small case series. The interventions have also been associated with reduced mortality, atelectasis, need for MV, and tracheostomy in a larger historical cohort comparison.
The reduction in VC associated with a change in position from supine to sitting is both statistically significant and clinically important. Hence, the seated position in which spirometric tests are usually performed is not optimal for patients with cervical SCI, in that FVC will be underestimated in this position.
Periodic chest roentgenography often discloses lesions in patients with tetraplegia, even in the absence of symptoms. Conversely, normal upright chest roentgenograms are not sensitive enough to exclude pulmonary abnormalities, particularly pleural effusions (which can be seen on lateral decubitus views).
In imaging the upper airway, tomography had better agreement with endoscopy for tracheal than glottic stenosis. Computed tomography was more accurate than tomography for diagnosing glottic stenosis, but was similarly accurate for grading the severity of tracheal stenosis.
Studies of bronchodilator effects suggest potential therapeutic benefit from long-term prophylactic therapy with inhaled beta-agonists to reduce symptoms of breathlessness associated with airway reactivity in persons with tetraplegia. However, none of these studies evaluated the long-term efficacy of bronchodilator or other drug treatments on symptoms, pulmonary function, or the incidence of pulmonary complications.
We also conclude the following:
Very little data are available with which to describe the risk of late ventilatory failure or the potential effectiveness of treatments to delay or prevent it.
Despite the expectations of non-disabled persons, the long-term perceived quality of life and well-being are similar in ventilator-dependent and autonomously breathing patients with SCI.
Further research must be performed to answer definitively questions about the best care for patients with acute and chronic cervical SCI. The evidence base of clinical research on the management of pulmonary disease in this condition covers only a small number of many important management decisions. In addition, the amount and quality of the literature is relatively poor, with few studies using RCT or other designs to reduce bias. Clinical research on patients with cervical SCI has primarily been limited to observational studies, and primarily retrospective case series. Determining the influences of the interventions is problematic for several reasons, including imprecise characterization of treatments and lack of appropriate controls. Few of the extant studies have any type of comparison group. Case series can provide rates of outcome events (e.g., complications, successful weaning) that can be compared across series (benchmarks). However, case series provide biased and imprecise estimates of relative effectiveness and are less powerful than study designs that offer internal comparisons (e.g., RCTs, concurrent cohort comparisons, and historical cohort comparisons).
There is also a need for more precise and consistent characterization of the patients in terms of important prognostic features such as LOI, completeness, and time since injury. Most of the evidence comes from retrospective case series in which the intervention is difficult to characterize. In various studies, the method of clinical care is either not described or described individually for each patient in the series. In some studies that describe well the protocol for care, it is not possible to estimate the effects for individual components of care.
Finally, many of the clinical studies had small sample sizes. A small size limits the generalizability of a case series. For more well-designed studies, the small sample sizes limit the statistical power; for example, the few RCTs identified in this study were negative and lacked the statistical power to show clinically important differences. Future studies should seek to improve both the generalizability and the statistical power by including more patients. Because of the relative rarity of the condition, it will be necessary to aggregate patients through merging standardized data sets from many institutions or developing multisite research networks.
The US Model Spinal Cord Injury Systems program is a network of (currently) 18 centers that work together to maintain a national database, provide continuing education, and participate in independent and collaborative research relating to SCI. The "Model Systems" database has contributed greatly to our knowledge of the prevalence, natural history, cost, and sequelae of SCI. The Model Systems data have clearly demonstrated improvement in survival of patients with SCI over the last few decades. Furthermore, the database, through measurement of incidence of complications, ventilator use at discharge, and other parameters, has been used to create benchmarks to guide the care of persons with SCI.
Currently the Model Systems database does not include detailed clinical data of the type needed to examine how differences in clinical practice (e.g., ventilator settings, frequency and type of respiratory therapy) might influence clinical outcomes such as weaning success, time on MV, incidence of atelectasis, or mortality. Agreeing on specific detailed clinical data to collect on day-to-day management practices for persons with SCI, and expanding the Model Systems database to include such data, would make it possible to correlate clinical practices with the health outcomes already obtained in Model Systems data. This would seem a natural extension of the current effort and would facilitate inter-site collaboration in the design and conduct of prospective clinical trials, which would be necessary to definitively answer questions of clinical management.
The Department of Veterans Affairs (VA) network of 23 designated SCI centers handles approximately two-thirds of VA inpatients visits for persons with SCI. The Department has recently developed a national registry of veterans with spinal cord dysfunction to allow more effective planning and administration for SCI care, both in the specialized centers and throughout the network of VA hospitals and clinics. Clinical data, obtained by linking data from the Department's patient treatment file, is, like the Model Systems database, insufficiently detailed for effective outcomes research.
Further queries of the Model Systems and VA databases are warranted to describe the occurrence of respiratory illnesses and complications in the course of care following SCI. Few of the currently available reports of Model Systems data have focused primarily on respiratory complications. Despite the lack of detailed data on treatment, the database does provide an opportunity to better describe the epidemiology of respiratory illness and complications. This more-detailed information could be useful for estimating the burden of illness, for modeling, or for cost-effectiveness analysis. These type of data, in turn, will provide motivation for funders to support collaborative clinical research efforts such as those described above.
An active clinical research network would offer the opportunity to implement protocols across multiple institutions, and to test for differences in outcomes associated with different protocols. A variety of management algorithms have been either described in the literature or put to use within systems or single institutions. None of these guidelines was developed using an explicit evidence-based process and none has been rigorously tested in clinical practice. The evidence compiled in this report will be used by the Consortium for Spinal Cord Medicine in their efforts to develop a new guideline using a more explicit process linking recommendations to evidence. Much of the justification for the current respiratory care of patients with tetraplegia comes from data on or experience with patients with other illnesses, thus guidelines on this topic will need to be based to a large extent on interpretation of these data. Explicit methods are needed for integrating data on related populations with our understanding of the pathophysiology of cervical SCI and other diseases. The Consortium for Spinal Cord Medicine, professional associations and similar groups, after examining the current state of research in this area, would be in a good position to outline an agenda for future research by prioritizing questions that would be most useful in guiding clinical care.
Most of the published research on pulmonary disease in SCI focuses on care of acutely injured subjects. As acute SCI is the most expensive condition among all causes for hospitalization, the acute management phase should be a high priority for research. However, as long-term SCI survival has increased, the prevalence of patients with chronic SCI grows ever larger. Pulmonary complications of chronic SCI will become of greater clinical importance. Currently, little data is available regarding the incidence of late respiratory failure, and even less is available on the effectiveness of therapies that may be effective to prevent it. In this instance, venues such as the VA Spinal Cord Injury Centers and the Model Systems institutions (in which cohorts of patients with chronic cervical SCI are followed) might decide that the systematic collection of data about their patients' clinical care could be valuable.
Reprinted with permission from The American Spinal Injury Association. Chicago: International standards for neurological and functional classification of spinal cord injury; 1996.
Reprinted with permission from The American Spinal Injury Association. Chicago: International standards for neurological and functional classification of spinal cord injury; 1996.
), can lead to tetraplegia, loss
of sensory function, and paralysis of the respiratory muscles. Patients with
paralyzed inspiratory muscles (principally the diaphragm) may not be able to
breathe on their own and often must be placed on mechanical ventilators;
patients with weak or paralyzed expiratory muscles (principally the abdominal
and intercostal muscles) may have impaired ability to cough and clear mucoid
secretions. The accumulation of retained secretions can lead to atelectasis and
pneumonia.
This report focuses on empirical studies relating to two research questions about (1) management of ventilatory insufficiency in acute and chronic phases, including weaning from mechanical ventilation (MV), management of secretions, atelectasis, and pulmonary infection, and (2) the prevention of late respiratory failure in patients with traumatic cervical SCI. Excluded from consideration were nonpulmonary complications of SCI and venous thromboembolism/pulmonary embolus. The report does not cover patients with SCIs occurring below the cervical level or respiratory muscle weakness caused by neuromuscular or other spinal cord diseases such as Guillain-Barré syndrome and polio.
The report describes the methodology used to search for, screen, abstract, and assess the quality of published research. It also provides the results of our analysis, conclusions, and recommendations for future research. The evidence is summarized in evidence table format in a later section of this report.
There have not been any studies of the overall incidence of SCI in the United States during the past decade. Recent reports from state-based SCI registries provide an estimate of the incidence of SCI in the United States at approximately 10,000 new cases each year (Acton, Farley, Freni et al., 1993; Price, Makintubee, Herndon et al., 1994; Thurman, Burnett, Jeppson et al., 1994; Woodruff and Baron, 1994), or 32 to 35 persons per million.
The prevalence of SCI is estimated at around 200,000 persons in the United States (DeVivo, Fine, Maetz et al., 1980; Harvey, Rothschild, Asmann et al., 1990; Lasfargues, Custis, Morrone et al., 1995). Causes of SCI include motor vehicle crashes in 43 percent, followed by acts of violence in 19 percent; falls in 18.8 percent; sports in 11.1 percent; and all other causes, 8.1 percent (Nobunaga, Go, and Karunas, 1999). Most persons with SCI are injured in their late teens or twenties, and men are about four times more likely to be injured than women (DeVivo, Rutt, Black et al., 1992). However, because persons with SCI are surviving longer, the average age is increasing. As persons with SCI age, so does the prevalence of co-morbid medical diseases, including pulmonary diseases. Overall, about half are cervical injuries, with the remaining half divided among thoracic, lumbar, or sacral injuries. The most frequent injury level is C5, followed by C4, C6, T12, and L1 (De Vivo, Richards, Stover et al., 1991) About half of injuries are neurologically complete (53.8 percent); incomplete injuries are divided between motor functional (27.2 percent) and motor non-functional sensory sparing (19 percent) (DeVivo, Krause, and Lammertse, 1999).
Although survival after SCI is improving, mortality rates remain considerably higher than for the population as a whole. Respiratory complications contribute to this excess mortality. Several studies document the importance of respiratory complications as causes of death (DeVivo, Black, and Stover, 1993; DeVivo, Krause, and Lammertse, 1999). It should be noted that all of these studies deal with the relative proportion of deaths that are due to respiratory causes. Importantly, if the mortality rate from respiratory causes decreases over time, but at the same rate that the mortality rate for other causes decreases, then no change will be observed in the relative proportion of deaths due to respiratory causes over time. Similarly, if the mortality rate from respiratory causes decreases over time, but the mortality rate from other causes decreases more quickly, then the proportion of patients with deaths due to respiratory causes will actually increase. This phenomenon was, in fact, observed by Frankel, Coll, Charlifue et al. (1998). Thus, analyses of cause of death are appropriate for establishing the importance of respiratory causes of mortality, but not for establishing the absolute impact of reducing mortality due to respiratory causes.
That said, 50 years ago the most common cause of death among patients with SCI was urinary tract infections. For the last 30 years or so, respiratory failure is the most common cause of death for patients with cervical injuries (particularly high-cervical injuries) during the acute phase of hospitalization, and one of the three most common causes of death subsequently. The most comprehensive data come from the US Department of Education, National Institute on Disability and Rehabilitation Research (NIDRR) Model Spinal Cord Injury Care Systems, also known as "Model Systems," which estimates the mortality from respiratory causes at 30 percent during acute hospitalization and 20 percent subsequently. In particular, from a large cohort of persons treated within an SCI Model Systems facility within 1 year of injury from 1973 to 1984, 226 patients with incomplete tetraplegia died; for the primary cause of death 20 patients had diseases of pulmonary circulation, 35 had pneumonia and influenza, and six had other respiratory causes (i.e., total 61/226 = 27 percent). In patients with complete tetraplegia, pulmonary complications were the primary cause of death in 132 of the 382 deaths (35 percent): 19 died from diseases of the pulmonary system; 93 from pneumonia and influenza, and 20 from other respiratory diseases. During extended followup, pneumonia was the leading cause of death for each age group and all time periods, but was much less common for patients with incomplete injuries (DeVivo, Black, and Stover, 1993). The findings of a more recent report from the SCI Model Systems, with followup extending through 1998, show similar trends in respiratory diseases (DeVivo, Krause, and Lammertse, 1999).
| Study | Population | Definition of pulmonary complications | Time after Injury | Comments | ||||||||
| Completeness of Injury a | Early Phase a | Late Phase a | ||||||||||
| IQ | CQ | AQ | IQ | CQ | AQ | IQs | CQ | AQ | ||||
| Nyquist, Bors, 1967 | Long Beach SCI Center | Pulmonary complications | 3/32 (9%) | 10/38 (26%) | One death at 45 days; all others at least 10 months post-injury | |||||||
| Silver, Gibbon, 1968 | Liverpool SCI Center | Chest complications, pneumonia, respiratory failure | 8/9 (89%) | 14/17 (82%) | Early = first 3 months post-injury | |||||||
| Wilcox, Stauffer, 1972 | California SCI Center | Pneumonia | 10/32 (31%) | Includes three deaths within first year | ||||||||
| Geisler, Jousse, Wynne-Jones et al., 1983 | Toronto SCI Center | Respiratory causes | 6/48 (13%) | 11/33 (33%) | All at least 1 year post-injury | |||||||
| Minaire, Demolin, Bourret et al., 1983 | French SCI Center | Acute respiratory insufficiency (often caused by bronchitis and/or airway obstruction) | 20/21 (95%) | Most deaths within 1 year post-injury | ||||||||
| Chen, Lien, 1985 | Taiwan general hospitals | Respiratory failure | 18/22 (87%) | Initial hospitalization | ||||||||
| Reines, Harris, 1987 | South Carolina neuro-surgical ICU | Pulmonary complications, primarily pneumonia | 14/22 (64%) | Initial hospitalization, includes six deaths among patients with paraplegia | ||||||||
| Kiwerski, 1992 | Polish SCI center | Primarily pneumonia | 66/82 (80%) | Patients with C1-C5 injuries | ||||||||
| Kiwerski, 1993 | Polish SCI Center | Primarily pneumonia | 21/37 (57%) | 157/206 (76%) | Initial hospitalization | |||||||
| Hartkopp. Bronnum-Hansen, Seidenschnur et al., 1997 | Danish SCI Center | Lung disease and pneumonia | 51/67 (76%) | Long-term followup, including early deaths | ||||||||
IQ = incomplete quads; CQ = complete quads; AQ = all quads.
The rate of respiratory complications is a particularly important parameter for benchmarking, estimation of public health burden, and cost-effectiveness analysis. Even among patients with cervical injuries, these complication rates differ by injury level and completeness, with patients having higher level of injury (LOI) and complete injuries being at highest risk. Accordingly, rates reported in the literature will differ according to population composition. In addition, rates will vary according to the definition of respiratory complications, and also according to the time from injury to the beginning of followup. In particular, the rate of respiratory complications is highest in the period immediately following SCI (Branscomb, Stover, DeVivo et al., 1984); thus, cohorts that include significant numbers of patients presenting some time after injury will have lower complication rates than those that begin to follow up patients soon after injury. Despite the above sources of heterogeneity, the literature consistently reports respiratory complications to be a very serious problem after SCI.
To quantify the above, various analyses by the SCI Model Systems give the complication rates during the initial hospitalization (acute care and rehabilitation) to be at least 20 percent for pneumonia and 20 percent for atelectasis (Kendall, Lafuente, and Hosie, 1997), these being the most common pulmonary complications (Branscomb, Stover, DeVivo et al., 1984). A subsequent report by Waters (Waters, Meyer, Adkins et al., 1999) is consistent with the above.
Using more extensive followup of patients admitted to one of five Model System facilities from 1985 to 1990 within 48 hours of injury, Jackson and Groomes (1994) give the proportion of patients experiencing at least one respiratory complication to be 84 percent for patients with LOI C1-C4, in comparison with 60 percent for patients with LOI C5-C8.
Fishburn, Marino, and Ditunno (1990) followed 30 patients admitted to a single facility, finding 14/19 patients (74 percent) with LOI C1-C4 developing atelectasis and/or pneumonia, in comparison with 3/11 patients (27 percent) with LOI C5-C7 (Fishburn, Marino, and Ditunno, 1990).
Reines and Harris (1987) followed 33 patients with injuries at LOI C1-C4, and found seven (21 percent) episodes of atelectasis, five (15 percent) episodes of pneumonia, and two (6 percent) episodes of aspiration. For 62 patients with injuries at LOI C5-C7, they found 11 (18 percent) episodes of atelectasis, six (10 percent) episodes of pneumonia, two (3 percent) episodes of edema, and three (5 percent) episodes of aspiration (Reines and Harris, 1987). Silver, Morris, and Otfinowski (1980) followed 51 patients with traumatic cervical SCI admitted to a British SCI center from 1971 to 1973; 15/51 (29 percent) developed pneumonia.
To our knowledge, Chen, Apple, and Hudson (1999) are the only investigators to present respiratory complications occurring in the initial episode of rehabilitation separately from those occurring in the initial acute hospitalization. Combining atelectasis and pneumonia, they estimated the rate of respiratory complications during the initial episode of rehabilitation at 13 percent.
Respiratory complications during the initial hospitalization (acute hospitalization and rehabilitation) are associated with increased likelihood of requiring MV, this in turn being associated with lower functional status (Fuhrer, Carter, Donovan et al., 1987), greater probability of nursing home placement, greater medical costs, and potential decrements in survival (DeVivo and Ivie, 1995). Although all of these outcomes are associated with level of injury, the association with respiratory complications holds even after controlling for level of injury.
More specifically, using a cohort of over 16,000 SCI Model Systems patients from 1973 to 1996, DeVivo (1999) found that approximately 16 percent of ventilator-dependent patients with tracheostomy were discharged to nursing homes, in comparison with 4 percent of patients who were able to breathe independently. Approximately 9 percent of patients with LOI C1-C4 were discharged on a ventilator, in comparison with 5 percent of those with LOI C5-C8. Approximately 35 percent of patients with traumatic cervical SCI require a ventilator at some point during the initial hospitalization (Kendall, Lafuente, and Hosie, 1997).
As the person with cervical SCI enters the late phase (months to years after injury), he or she has a continued risk of pulmonary complications. An elevated risk for atelectasis and pneumonia persists. For persons who breathe on their own, there is a risk of late-onset ventilatory failure (Bach, 1993). Several factors can contribute to late ventilatory failure, including late neurologic deterioration, lung disease, and restrictive ventilatory impairments. Late neurologic deterioration can occur from syringomyelia, for example. Recurrent episodes of atelectasis and pneumonia may lead to chronic lung disease. Restrictive ventilatory impairment may result from kyphoscoliosis or obesity.
The most comprehensive data on annual rates of respiratory complications are provided by McKinley, Jackson, Cardenas et al. (1999), using routine annual evaluations of SCI Model Systems patients. For patients with incomplete injuries, the probability of experiencing at least one episode of pneumonia and/or atelectasis during the preceding year was 3.1, 3.8, 3.3, 2.2, 1.8, and 0.0 percent for 1, 2, 5, 10, 15, and 20 years post-injury, respectively. For patients with complete injuries, these figures were 9.9, 9.8, 6.4, 4.9, 4.1, and 3.7 percent. This gradual decrease in rates may be the result of differential survival, as those patients who suffer respiratory complications are at a higher risk for death.
In an analysis of data from an independent living facility, Meyers, Bisbee, and Winter (1999) found the annual rate of respiratory infections (e.g., including influenza and pneumonia, but not colds) to be in the range of 18 to 25 percent for persons with SCI. The higher rates found in this study were likely inflated by self report and inclusion of less serious infections.
Acute cervical SCI is a devastating injury that completely changes a patient's way of life. Hospitalization for acute care is usually prolonged and followed by a lengthy period of rehabilitation and readjustment. The burdens include enormous costs for acute medical care, rehabilitation, medications and supplies, modification to home and vehicles, and personal assistance.
SCI is a very expensive condition to treat. The Agency for Healthcare Research and Quality (AHRQ) reports an average hospital charge incurred (not including professional fees, rehabilitation, or rehospitalization) of $56,800 per patient per hospitalization in 1996 (AHRQ, 1999). Other estimates of the cost of initial hospitalization for acute SCI are even higher, ranging from $87,238 in persons with paraplegia to $156,790 in persons with tetraplegia, also in 1996 dollars (Berkowitz, O'Leary, Druse et al., 1998). Post-injury rehabilitation costs are also burdensome, averaging $139,180 for tetraplegic patients (Berkowitz, O'Leary, Druse et al., 1998).
There have been few studies of the economic impact of respiratory complications among patients with SCI. Based upon a small sample of only eight patients, Johnson, Brooks, and Whiteneck (Johnson, Brooks, and Whiteneck, 1996) found the mean increase in acute care costs attributable to a respiratory complication to be $13,000. However, this is likely to be an underestimate, as only one-third of the excess costs in the data set could be attributed to a specific complication. In a small case series, Tator, Duncan, Edmunds et al. (1993) found that respiratory complications increased the mean length of stay by 27 days. In another small case series, Branscomb, Stover, DeVivo et al. (1984) found the mean duration of complications to be 20 days for patients with high-level quadriplegia and 14 days for patients with low-level quadriplegia. Thus, the economic data, although sparse, are fairly consistent.
Considering patients with high-level tetraplegia, Fuhrer, Carter, Donovan et al. (1987) compared 14 patients who were ventilator-dependent on their initial discharge with 143 patients who were not. At 1 year post-injury, 89 percent of ventilator-independent patients (primarily complete injuries at C4) were living at home, in comparison with 79 percent of those requiring a ventilator to breathe (primarily complete injuries at C1 to C4). Current lower reimbursement for in-home caregiving suggests these percentages may be higher now. The ventilator-dependent group required a greater number of hours of caregiver time per week as well (Fuhrer, Carter, Donovan et al., 1987).
Breathing involves two distinct phases, inspiration and expiration. Inspiration is an active process. Expiration is almost entirely passive at normal tidal volumes, though in heavy breathing there is an additional active component. In inspiration, the diaphragm, scalenes, and the intercostal muscles contribute significantly to tidal volume, with the diaphragm being the most important. Several other muscles play an auxiliary, or accessory, role in inspiration, including the trapezius, levator scapulae, pectoralis, serratus anterior, costal levators, and others. In expiration, the intercostals and oblique abdominals play an active role.
In cervical SCI, some or all of the muscles responsible for breathing are affected. Lower-cervical injuries will affect the scalenes (innervated by cord levels C4 to C7), the intercostals (T1 to T11), the oblique abdominals (T6 to L1), and the rectus abdominus. High-cervical cord injuries affect the diaphragm (innervated by C3, C4, and C5), as well as all of the previously mentioned muscle groups.
Without active chest wall expansion during inspiration from intercostal muscles, the breathing efforts of patients with tetraplegia are inefficient, and the chest wall contracts in a paradoxical movement. Pulmonary function tests (PFTs) show low forced vital capacity (FVC) (Forner, 1980) and reduced lung and chest wall compliance. After the acute period following SCI, pulmonary function shows improvement over time in most patients. However, currently available data fail to show an association between the rate or amount of improvement and PFTs, neurologic examination, or muscle function evaluations in the early phases of recovery (Axen, Pineda, Shunfenthal et al., 1985). The mechanism through which improvement in vital capacity occurs without improvement in neurological function is believed to be the spasticity that develops in the intercostal and abdominal musculature, which stabilizes the rib cage, thus allowing for more biomechanically effective diaphragmatic action.
Patients with complete lesions above C4 require mechanical ventilatory support in the acute phase. Those with complete lesions below C4 can, after the acute phase, and barring pulmonary complications, breathe independently. Those patients with complete injury at the C4 levels (and sometimes at the C3 level) represent particular challenges, as they have the potential to breathe on their own, but have little reserve. Any pulmonary compromise due to secretions or atelectasis or infection thus can result in ventilatory insufficiency and the need for MV. Injuries at C6 level and below do not usually require ventilatory support unless other pulmonary complications or injuries exist. Among patients with incomplete lesions, the LOI is not so clearly associated with the need for mechanical ventilatory support, and even patients with C2 or C3 LOI sometimes do not require MV.
Paralysis of the abdominal muscles (T6 to T12) results in the inability to cough effectively. Poor ventilation and poor cough can lead to retained secretions, mucous plugging, and atelectasis. Atelectasis allows bacterial overgrowth and ultimately pneumonia. Furthermore, cervical lesions lead to a loss of sympathetic nervous system innervation, causing a parasympathetic imbalance that, in the lung, leads to bronchoconstriction and increased mucous secretion. The increased mucous secretions compound the problem of impaired clearance.
| Time Period | Setting | Interventions | |||
|---|---|---|---|---|---|
| Ventilation/Airway | Speech | ||||
| Minutes to hours | Emergency care | Intubation | NG tube | Suction, bronchodilators | - |
| Hours to days | Acute care hospital, neurology ICU | - | - | - | - |
| Days to weeks | - | Tracheostomy, complication | G tube | Physical therapy, bronchoscopy, IPV, mechanical insufflation-exsufflation | Cuff deflation |
| Weeks to months | Rehabilitation facility | Weaning, NPPV | - | Mucolytic Rx, IPV, mechanical insufflation-exsufflation | - |
| Months to years | Home, outpatient care, rehabilitation or SCI facility | Chronic ventilatory management Diaphragm pacing (tracheostomycomplication) Predictors of late respiratory failure | - | - | - |
G = gastric; ICU = intensive care unit; NG = nasogastric; NPPV = noninvasive positive pressure ventilation; SCI = spinal cord injury.
In the following sections, each of the most important pulmonary management issues are addressed: acute ventilatory insufficiency, weaning, and chronic ventilation support.
Signs and symptoms associated with acute ventilatory failure include tachypnea, dyspnea, and drowsiness or declining mental alertness. These symptoms may develop in acutely injured patients due to progression of neurologic injury, fatigue of respiratory muscles, or pulmonary complications such as atelectasis or pneumonia. Arterial blood gas, pulmonary function tests, pulse oximetry, and end-tidal CO2 monitoring may be helpful in confirming the diagnosis of acute ventilatory failure.
Therapeutic interventions for acute ventilatory failure include mechanical ventilatory support, which provides MV by means of endotracheal or nasotracheal intubation, tracheostomy, face or nasal masks, or mouthpiece and mouthpiece with lipseal retention. Less-intensive ventilatory support can be accomplished through continuous positive airway pressure (CPAP), bilevel positive airway pressure, or glossopharyngeal breathing (GPB). Oxygen supplementation may be helpful in patients with underlying lung disease, but its use should be carefully monitored, as it may mask signs and symptoms of carbon dioxide retention.
Weaning from MV consists of maneuvers intended to allow the patient to become independent of ventilator support. Weaning may be accomplished in several ways: (1) keeping the patient on limited ventilator support, but changing the ventilator function to reduce the assistance provided; (2) removing the patient from ventilator support for limited periods of time that are progressively increased; or (3) providing an alternative means of ventilatory support, for example, intermittent abdominal pressure respiration, GPB, or electrophrenic respiration (EPR).
Reduced ventilator support is most often accomplished through synchronized intermittent mandatory ventilation (SIMV) mode, which allows the patients to take breaths through the ventilation system between positive pressure ventilator breaths, which are triggered only if the respiratory rate or minute ventilation volume do not reach minimum pre-set values. In weaning, these minimum values are gradually decreased. This is the weaning method used most commonly in a wide variety of medical and post-surgical conditions. Alternatively, pressure support ventilation provides positive pressure during patient-initiated respiration. In weaning, the amount of pressure delivered during inspiration is gradually reduced. SIMV and pressure support ventilation are convenient in that they use existing equipment and staff; however, they offer neither a sustained period of respiratory muscle conditioning nor rest.
Removal of ventilator support for limited periods of time is often accomplished by using a T-piece, with one end open to atmospheric pressure. Patients may be placed on a T-piece for brief periods of time at first, with the duration of ventilator-free periods progressively increased as the patient's independent respiratory capability improves. Non-invasive ventilation with a mouthpiece, allowing the patient to take ventilator-assisted breaths as needed, has been described as an alternative to the more standard SIMV or T-piece weaning techniques (Bach, 1991; Bach and Alba, 1990a; Bach and Saporito, 1996).
Patients with tetraplegia with lower-cervical LOI (C5 or below) are easier to wean than those with higher-level injuries. Those with C2-level complete injuries are not candidates for weaning because they can be expected to have no intact diaphragmatic function. However, patients with incomplete C2 or below lesions or complete C3 or below lesions might be successfully weaned. The decision of when to begin attempts at weaning is individualized. Some studies articulate criteria used. Most such criteria insist on the absence of cardiopulmonary problems and acute infections, as well as minimal values for spirometric indices. Several studies gave threshold values for VC before weaning should be attempted. These values varied from a VC of at least 300 mL (Gardner, Watt, and Krishnan, 1986), more than 10 mL/kg body weight (Lamid, Ragalie, and Welter, 1985), or as little as 100 mL (Peterson, Brooks, Mellick et al., 1997).
Patients with cervical SCI who are unable to wean from ventilatory support need some form of chronic mechanical ventilatory assistance. During the acute phase, invasive MV is most often accomplished using an endotracheal tube. However, this interface is not appropriate for chronic ventilation; the endotracheal tube is not easily replaced if dislodged and can cause tracheal stenosis and other local effects. Thus, if prolonged MV is required, the usual approach to securing the airway involves a tracheostomy. However, a tracheostomy tube interferes with speech. Other options for management of chronic ventilatory failure include use of noninvasive positive pressure ventilation (NPPV), intermittent abdominal pressure respiration, EPR, and respiratory muscle conditioning (with eventual weaning).
Tracheostomy positive pressure ventilation (PPV) is the usual next step for patients on endotracheal tube PPV who cannot be weaned from ventilatory support within a few weeks. In order to permit speech, modifications need to be made to permit air leakage around the tracheostomy tube. This has been described in several ways: the use of cuffless tracheostomy tubes or in-line one-way speech valves (Passy-Muir valves), which permit leakage around the tube (between the tube and the tracheal wall), or fenestrated tubes, which permit air to escape through holes in the cephalad portion of the tracheostomy tube. With both of these techniques, the leakage requires increased volumes of air to be delivered by the ventilator and often results in hypocapnia.
Chronic noninvasive ventilation (NIV) has been described as a means of providing chronic ventilatory support in patients with cervical SCI by assisting ventilation without using an endotracheal tube to establish an airway. There are two types: negative and positive pressure ventilation. Noninvasive negative pressure ventilation (NNPV) uses devices (total body chambers [iron lungs], or chest wraps) that surround the patient's thorax and enable lung expansion by applying negative (subatmospheric) extra-thoracic pressure during inspiration. However, iron lungs are confining to patients, restrict healthcare providers' access to patients, and require a great deal of space. The simpler chest wraps are also cumbersome to use and difficult to operate properly. Because of these difficulties, NNPV has been replaced by NPPV for nearly all cases (Bach, 1996).
NPPV delivers positive airway pressure from a ventilator through an interface into the patient's upper airway and lungs during inspiration. Interfaces are nasal-only or nasal/facial mask types and include nasal mask, nasal pillows, nasal-oral device, full face mask, or mouthpiece. Both interfaces will leak (nasal interfaces leak through the mouth; facial masks leak around the mask at the skin), and the NPPV system must be designed to accommodate this leak. A number of ventilator modes have been used to provide NPPV. Volume-cycled modes deliver a set flow and volume, whereas pressure-targeted modes deliver a set pressure with each breath. Positive end expiratory pressure (PEEP), supplemental oxygen, and backup mandatory breath rates can be provided as clinically indicated. Although conventional intensive care unit (ICU) ventilators can be adjusted to provide support through a mask interface, there are other options, including portable volume ventilators and BiPAP®. Portable volume ventilators with an oral interface allow intermittent positive pressure ventilation and allow patients to "stack" consecutively delivered breaths held with the glottis closed to be able to cough effectively. In addition, several simple pressure-targeted systems specifically designed for mask applications (e.g., BiPap®) are clinically available. For NPPV to be most effective, patients must be able to cooperate and coordinate their breathing with the ventilator. If not, breathing is actually hampered, not augmented. Usually a respiratory therapist or a nurse trained in NPPV techniques is required to monitor patients for ventilator-breathing synchrony and to make sure the equipment is functioning properly. That professional will also follow the patient for signs of physical improvement or deterioration. This monitoring is best performed in either an ICU or in another specialized ventilatory/respiratory care unit.
EPR, or phrenic nerve pacing, is an artificial respiration technique in which electrodes surgically implanted around the phrenic nerves or diaphragm are stimulated to induce cyclical diaphragmatic contraction and, hence, ventilation of the lungs. The use of phrenic nerve pacing in a tetraplegic patient with chronic ventilator dependency was first described in 1972 (Glenn, Holcomb, McLaughlin et al., 1972). The pulse generator is surgically implanted and may be controlled by an external radiofrequency transmitter pacemaker. Various techniques and routes of phrenic nerve and diaphragm stimulation and a variety of pacemaker technologies have been reported.
EPR has the potential advantage of being more portable and of providing better speech and perhaps a more normal airway physiology than positive pressure ventilator techniques provide. However, not every SCI patient with chronic respiratory failure is a suitable candidate for this procedure. It generally requires an intact and viable phrenic nerve (although intercostal nerve grafts have been used), and response of the diaphragm to electrical stimulation on pre- or intra-operative testing. For the phrenic nerve to remain viable, the cell bodies and nerve axons originating in segments C3, C4, and C5 of the spinal cord must be intact. The use of EPR is further limited by diaphragm fatigue and deconditioning occurring between the onset of trauma and electrophrenic implant. EPR is frequently used unilaterally, thereby causing paradoxic motion of the contralateral diaphragm (Pedulluft breathing). EPR also does not allow the pressure increases that, with glottic closure, are needed to cough and can contribute to obstructive sleep apnea, necessitating that tracheostomies be kept.
The intermittent abdominal pressure respirator, also known as an exsufflation belt (or pneumobelt), assists in expiration rather than inspiration. It is a corset-type device that is placed around the abdomen and usually used only when the patient is awake and in an upright position. An inflatable bladder within the corset fills, thus compressing the abdominal wall, causing the diaphragm to rise, and producing active expiration. When the bladder deflates, passive inspiration results as the abdominal contents and diaphragm return to their regular position by gravity. Like NPPV, the intermittent abdominal pressure respirator allows for ventilation without a tracheostomy.
Ventilatory failure also may occur late in the course of SCI in patients who have been breathing on their own for years, and is associated with acute changes in respiratory demands (e.g., pneumonia) or with progressive decline in pulmonary or neurologic function. Signs and symptoms associated with indolent ventilatory failure include tachypnea, dyspnea, daytime drowsiness, fluctuating mental alertness, unexplained erythrocytosis, and increased positional influences on breathing.
All patients with SCI have an impaired ability to clear secretions. Retained secretions may plug bronchi and lead to atelectasisand eventually to pneumonia. Because patients with SCI have decreased sensation of respiratory distress, the only signs and symptoms of impending respiratory failure from mucous plugging may be anxiety and increased respiratory rate. Failure to respond quickly to major mucous-plugging events may lead to respiratory arrest and death. Fever and purulent sputum may mark progression to pneumonia. Chest roentgenography is used to diagnose atelectasis or pneumonia, swallowing studies may identify potential for aspiration, and fluoroscopy or ultrasound can identify diaphragm paralysis.
Treatment methods include postural drainage and chest percussion, active suction, assisted cough, and rotating beds. In addition, intermittent positive pressure breathing (IPPB) with breath stacking or mechanical insufflation-exsufflation with concomitant abdominal thrusts and intrapulmonary percussive ventilation can be used to promote secretion clearance. Bronchodilating and mucolytic drugs may improve ventilation and reduce secretions. Fiberoptic bronchoscopy is also used to remove recalcitrant mucous plugs.
Postural drainage (positioning the patient so drainage occurs by gravity) is often assisted by chest physiotherapy or clapping hands on a patient's chest and back to loosen secretions in the bronchi. Several approaches have been used to assist cough, including manual pressure applied to the abdomen (timed with a patient's cough effort), positive pressure insufflation, mechanical insufflation-exsufflation (coughalator), and electrical stimulation of the abdominal muscles. Each of these methods requires the active intervention of a caregiver; each also requires coordination with the patient's control of opening and closing the upper airway. Rotating beds place a patient in a continuous turning motion in which he or she is turned equally from side to side. The potential benefits of mobilizing patients with SCI in this way may include reducing dermatological, cardiovascular, and other complications; it may also reduce pulmonary complications by improving secretion clearance and reducing atelectasis. Continuous turning is associated with continuous postural drainage. In addition, vibration, which is available on some rotating beds, may also encourage movement of mucus out of the lungs. The use of rotating beds has been associated with reduced rate of pulmonary complications in patients with SCI in general (Brackett and Condon, 1984).
We focused on patients with acute traumatic cervical SCI, regardless of the degree of completeness of injury. We are interested in treatment in the days to months following acute injury and also the long-term followup over years.
We expected that among studies of patients requiring ventilatory support, and for certain techniques such as diaphragmatic pacing, the majority of patients using these technologies would have high-cervical SCI. However, patients with low-cervical injury or incomplete injury are also at high risk of late respiratory failure and are a relevant population to study for the effectiveness of interventions to prevent this outcome.
We did not consider persons with thoracic and lumbar SCI among the target population because with intact diaphragm function, the respiratory problems are generally less severe and less common than those in persons with cervical SCI. Furthermore, because of this physiological difference, data on persons with thoracolumbar SCI would not be relevant to persons with cervical SCI.
We did not include children as part of the target population for two reasons: (1) empirical evidence in the literature is almost nonexistent, and (2) there are probably differences in the management of their care, e.g., noninvasive ventilation may be more difficult in children than in adults.
Initial management of acute injury may begin at the site of injury by emergency caregivers and can continue in emergency departments or trauma centers. Issues such as airway management (intubation technique) are relevant in this time frame. This settingwas not included in the scope of this report.
The principal audience of our report is healthcare providers likely to care for persons with acute SCI or chronic SCI. We expect that this will include primary care, pulmonary, physical medicine, and rehabilitation physicians; respiratory therapy and nursing professionals; and members of rehabilitation teams including physical therapy, occupational therapy, speech therapy, and social workers.
This section describes the basic methodology used to develop the evidence report beginning with the topic assessment and refinement through the literature search, screening, and data abstraction process. Included are the literature search strategies, literature sources, screening criteria, and quality control procedures.
The key questions in the original Request for Task Order Proposals for this evidence report were very broad. After Duke's initial proposal was submitted, these questions were discussed in a conference call that included the Duke research team, AHRQ staff, and members of the Consortium for Spinal Cord Medicine (which nominated the topic). The Consortium proposed a refined list of topics that more closely represented their information needs. These issues were the focus of a revised proposal that was subsequently approved by AHRQ:
Management of the acutely injured patient to prevent respiratory failure, with emphasis on secretion control, atelectasis, aspiration, and pneumonia
Selection of criteria for determining placement on a ventilator
Identification of optimal ventilator parameters to preserve lung compliance and prevent atelectasis
Establishment of criteria for weaning the SCI patient from MV
For patients with chronic SCI who breathe on their own, determination of the key medical and therapeutic measures to prevent recurrence of respiratory failure, including prevention/management of late respiratory failure
Proper management of tracheostomy to allow speech
Complications of intubation and tracheostomy and how to prevent them
Indications and timing for bronchoscopy
Optimal use of medications and prophylactic respiratory therapy modalities, including IPPB, assisted cough, postural drainage, bronchodilators, humidification, spirometry, vital capacity (VC) assessment, etc.
Establishment of parameters for phrenic nerve stimulation
Ventilator management in the context of rehabilitation, including balancing weaning, speech, swallowing, and mobility
Essential equipment and optimal methods for accommodating persons on a ventilator in the home.
A national advisory panel of technical experts was convened to work with the Duke
research team. The eight-member panel was composed of pulmonologists,
rehabilitation specialists, a respiratory therapist, a patient care
representative (who specializes in SCI), and the Consortium's representative.
Peter Almenoff, MD, VA Medical Center, Kansas City, MO
Fred Cowell,
Paralyzed Veterans of America, Washington, DC
J. Douglas Hussey, MBA,
RRT, VA Puget Sound Health Care System, Seattle, WA
Steven C.
Kirshblum, MD, Kessler Rehabilitation Institute, West Orange, NJ
Kenneth C. Parsons, MD, The Institute for Rehabilitation and Research, Houston,
TX, and the Consortium for Spinal Cord Medicine, Washington, DC
Peter
Peterson, MD, Craig Hospital, Denver, CO
Ann Marie Smith, PhD, RN,
CRRN, CANP, Ohio State University Medical Center, Columbus, OH
Andrew
D. Zadoff, MD, Shepherd Center, Atlanta, GA
Prior to the first meeting of the advisory panel via conference call, the panel received a document that, in a summary fashion, assessed the incidence and prevalence of pulmonary disease following SCI; described the characteristics and size of the affected population; identified the most affected practice settings and providers; assessed the burden of illness; and investigated the extent to which there is variation in practice associated with the prevention, diagnosis, treatment, or management of pulmonary disease following SCI.
The panel was also presented with the 12 key questions specified in the task order, grouped into four major topic areas: acute management (item 1 on list above); ventilator management (items 2, 3, 4, 10, 11, and 12); tracheostomy (items 6, 7, and 8); and prevention of late respiratory failure (items 5 and 9). From these four topic areas, Duke proposed to address two questions related to ventilator management and prevention of late respiratory failure, specifically the following:
For persons with traumatic high cervical SCI who are at high risk of respiratory failure or require ventilator support, what are the best practices regarding ventilator management? Specifically,
What characteristics predict need for initiation of mechanical ventilation?
What characteristics predict success in weaning from mechanical ventilation?
What ventilator management techniques improve the ability to wean from MV?
What are safe and effective techniques for intubation and airway management?
What are ventilator management techniques that can preserve lung compliance, prevent atelectasis, reduce the risk of complications?
For persons with traumatic cervical SCI who breathe on their own, what interventions -- including medications (bronchodilators, mucolytics) and prophylactic respiratory therapy NPPV, assisted cough, postural drainage, humidification, spirometry, VC assessment)--are effective to reduce the risk of late respiratory failure?
Ventilator management issues were limited to patients with cervical SCI because this population either requires ventilatory support or is at high risk of respiratory failure. All acute management issues would have exceeded available time and budget; thus, those aspects of acute management that were most closely linked to ventilator use were included, such as decisionmaking about initiation of mechanical ventilation and intubation techniques. The long-term ventilator management literature appeared to be of moderate size and consisted mainly of case series with a few cohort studies. Almost no randomized controlled trials were available, but some studies used concurrent or historical controls as comparison groups.
There was an additional body of literature considered. These were studies using small cohorts to examine individual self-contained issues such as optimal ventilator design. Outcome variables in these studies were often proximal, e.g., laboratory parameters rather than clinical outcomes that are of ultimate interest.
Prevention of late respiratory failure is a main goal of therapy for patients with cervical SCI who breathe on their own. Longitudinal data on rate of late ventilatory failure was sought by level of injury. While there are a wide range of techniques listed in the questions above, the literature describing clinical effectiveness is small. Although populations with respiratory muscle weakness (of other etiologies, such as Guillain-Barr? syndrome) may be similar in risk for late respiratory failure, they differ sufficiently in pathophysiology that we excluded these populations.
The advisory panel recommended no significant changes to the proposed focus.
The comprehensive review of the literature, from identification of databases through abstraction of individual articles into evidence tables, was a multistep, sequential process.
The primary sources of literature were four of the most widely used computerized bibliographic databases: MEDLINE (1966-Feb 2000) (MEDLINE [database online]), HealthSTAR (1975-Feb 2000) (HealthSTAR [database online]), Cumulative Index to Nursing & Allied Health Literature (CINAHL) (1983-Feb 2000) (CINAHL [database online]) and EMBASE (1980-Feb 2000) (EMBASE [database online]). These searches were supplemented by secondary searches, including e-mail subscriptions for announcements of newly published journals and thorough searching of reference lists in all included articles and review articles. In addition, the Cochrane Controlled Trials Register and Cochrane Database of Systematic Reviews were searched, but did not yield useful literature.
The search strategies were initially developed using the National Library of Medicine Medical Subject Heading (MeSH) key word nomenclature developed for MEDLINE. The same search strategy was used for HealthSTAR and CINAHL. A Duke University Medical Center librarian checked our basic strategies and assisted with their translation to the key word structure used by EMBASE. Each online search began with the first year of the database (specified in the preceding Literature Sources section).
The search strategies combined an SCI concept (implemented using MeSH terms spinal cord injuries, paraplegia, and quadriplegia [exploded] and text words for tetraplegia, quadriplegia, and paraplegia) with a pulmonary disease concept. The search was limited to articles pertaining to humans and published in the English language. The exact texts of the strategies are provided in Appendix A.
Inclusion and exclusion criteria were developed for the literature searches so that the yield of articles would be appropriately focused.
Empirical studies or review articles were included after screening by the following criteria:
The study population must include traumatic cervical SCI.
All studies relating to the research questions described above were included.
Outcomes were included if they were health outcomes, health services utilization or economic outcomes, or physiological measures related to respiratory status.
The study design included controlled trials, prospective trials with historical controls, prospective or retrospective cohort studies, and medium- to large-sized case series.
The criteria used to exclude articles:
Article was not original research (relevant reviews were included only if they focused on management of traumatic cervical SCI or on pulmonary disease in other SCI or neurological diseases).
Article did not address traumatic cervical SCI.
Focus of the article was not pulmonary disease.
Article focus was a pediatric population (all subjects or mean age < 18 years).
The study design was a single case report.
The study design was a small case series with fewer than 20 subjects.
The pulmonary condition was thromboembolism or pulmonary embolism.
The article was a review.
Other articles that did not meet the inclusion criteria.
The inclusion and exclusion criteria related to small case series were initially defined with a threshold of less than 20 subjects. The advisory panel recommended this threshold, with the proviso that if there were relatively few randomized controlled trials (as was the case), then the threshold should be lowered to 10 subjects. Appendix A provides a list of the articles that were excluded because they were small case series with fewer than 10 subjects. Exclusion criteria for review articles and "other" articles were added at the full-text screening stage. The screening form is provided in Appendix A.
Our literature search yielded 1,888 English language articles. The abstract of each article in the database was reviewed against inclusion/exclusion criteria by four investigators, Drs. Joseph Govert, David Matchar, Douglas McCrory, and Gregory Samsa. Each abstract was reviewed by teams of two of these investigators. Abstracts were available for more than three-fourths of the citations; however, when no abstract was available, the title, source, and MeSH words were reviewed. At this stage, an article was included if requested by one member of the review team.
Each abstract in the first set to be reviewed (n = 340) was reviewed by all four investigators, and a kappa statistic was calculated to determine the strength of the agreement to include or exclude articles and the reason for exclusion. One review team had good agreement (kappa = 0.590; confidence bounds = 0.447 to 0.733); their disagreements were largely on the inclusion of small case series, which were easily resolved. The other team had poor agreement (kappa = 0.185; confidence bounds = 0.050 to 0.319) resulting from misinterpretation of the selection criteria. After clarifying the criteria, another kappa statistic was calculated for this team on a subsequent set of 329 abstract screening decisions, and the result was a much improved kappa score of 0.402, with confidence bounds of 0.204 to 0.600. Because agreement was still only fair, articles were retained if selected by either reviewer.
At the full-text screening stage, each article was independently reviewed by two investigators who forwarded their decisions to the project manager for recording and comparison. If indicated, they were asked to reconcile differences of opinion. Overall, the teams disagreed on about 15 to 20 percent of their decisions, and all were reconciled for total agreement on all articles. In the event the two investigators could not agree, Dr. Douglas McCrory, the principal investigator, would be the arbiter; however, the need for arbitration did not arise.
| Database | Number of Records | Percent of Total (%) |
|---|---|---|
| MEDLINE | 1,365 | 72.3 |
| EMBASE | 488 | 25.9 |
| CINAHL a | 4 | 0.2 |
| None (from reference lists or newly published journals) | 31 | 1.6 |
| Total | 1,888 | 100 |
CINAHL = Cumulative Index to Nursing & Allied Health Literature.
| Description | No. | Percent (%) |
|---|---|---|
| Abstracts | ||
| Number of abstracts reviewed a | 1,888 | - |
| Number included | 502 | 26.6 |
| Number excluded | 1,386 | 73.4 |
| Reasons for exclusion b | ||
| 1-Not original research | 19 | 1.4 |
| 2-Not spinal cord injury | 688 | 49.6 |
| 3-Not pulmonary disease | 457 | 33.0 |
| 4-Pediatric population | 48 | 3.5 |
| 5-Single case report | 64 | 4.6 |
| 6-Small case series (N < 10) | 57 | 4.1 |
| 7-Thromboembolism/pulmonary embolism | 53 | 3.8 |
| Full-Text Articles | ||
| Number of full-text articles reviewed | 502 | - |
| Number of relevant articles | 157 | 31.1 |
| Number of articles included in evidence tables, i.e., efficacy articles | 81 c | 16.0 |
| Number excluded | 345 | 68.9 |
| Reasons for exclusion b | ||
| 1-Not original research | 36 | 10.4 |
| 2-Not spinal cord injury | 37 | 10.7 |
| 3-Not pulmonary disease | 74 | 21.4 |
| 4-Pediatric population | 12 | 3.5 |
| 5-Single case report | 50 | 14.5 |
| 6-Small case series (N < 10) | 66 | 19.1 |
| 7-Thromboembolism/pulmonary embolism | 1 | 0.3 |
| 8-Review article | 65 | 18.8 |
| 9-Other (no quantitative data or no separate results reported) | 4 | 1.2 |
Some records did not contain abstracts.
Only one reason for exclusion is listed for each article. The reasons for exclusion were applied in sequence, so that an article excluded for reason #4 might also fail reasons #5-7 but can be assumed not to have failed for reasons #1-3.
Of the 81 articles, 27 were included after the inclusion criteria were changed to admit case series with between 10 and 20 subjects.
The template of the data abstraction form is in Appendix A. The data were abstracted directly from the article into the evidence table format. Dr. McCrory was responsible for checking all data abstracted by a non-clinician abstractor and for summarizing articles on pathophysiology. Dr. Samsa summarized all articles on epidemiology and health services utilization.
| Type of Outcome b | No. (%) Studies in Ev. Tables Reporting These Outcomes |
|---|---|
| Health State | |
| Mortality (no. of pts who died, cause of death, etc.) | 30 (38) |
| Nonfatal complications (adverse events, pneumonia, atelectasis, stenosis, etc.) | 27 (34) |
| Quality of life | 4 (5) |
| Health Services | |
| MV (no. of pts ventilated, need for MV, etc.) | 14 (18) |
| Weaning (no. of pts successfully weaned, amt. of time to achieve weaning) | 13 (16) |
| Tracheostomies | 10 (12) |
| Electrophrenic or diaphragmatic pacing | 9 (11) |
| Hospitalization (duration of, no. of hospitalizations) | 9 (11) |
| Discharge status (no. of pts discharged to home, etc.) | 7 (9) |
| Spirometry | |
| VC or FVC | 35 (44) |
| FEV or FEV1 | 15 (19) |
| PEF and/or PEFR | 8 (10) |
| TLC | 7 (9) |
| Other | |
| PC20 | 5 (6) |
| Antibodies (mean antibody concentrations - pneumonia vaccination) | 2 (2) |
Ev. = evidence; FEV = forced expiratory volume; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; PC20 = provocative concentration of methacholine or histamine that causes a 20% decrease in FEV1; PEF = peak expiratory flow; PEFR = peak expiratory flow rate; pts = patients; MV = mechanical ventilation; TLC = total lung capacity; VC = vital capacity.
Identity of studies reporting each outcome is listed in Appendix B.
| Level | Description |
|---|---|
| I | Large randomized trials with clear-cut results (and low risk of error) |
| II | Small randomized trials with uncertain results (and moderate to high risk of error) |
| III | Nonrandomized trials with concurrent or contemporaneous controls |
| IV | Nonrandomized trials with historical controls |
| V | Case series with no controls |
Sources: Sackett, DL. Rules of evidence and clinical recommendations on the use of antithrombotic agents. Chest 1989;95(2 Suppl):2S-4S; and the U. S. Preventive Health Services Task Force. Guide to clinical preventive services. 2nd ed. Baltimore: Williams & Wilkins; 1996. Used with permission.
|
We employed quality-monitoring checks at every phase of the literature search, review, and data abstraction process to reduce bias, enhance consistency, and to check accuracy of study review:
Advisory panel review of the literature search strategy
Medical librarian review of the literature search strategy
Check on completeness of the literature search results by solicitation of key citations from the advisory panel
Check on completeness of the literature search results through reference list checks by the article reviewers
Kappa statistics to demonstrate strength of agreement among and between reviewers
Corrective action to increase strength of agreement of one review team, which includedanother kappa test
Reconciliation of all differences of opinion by reviewers on all full-text articles
Agreement of two reviewers for all eligible studies
Training and oversight of abstractor by a clinician-investigator
Solicitation of advice at key decision points from study consultants, Dr. Byron Hamilton and Dr. Michael DeVivo
Solicitation of advice at key decision points from the advisory panel of technical experts
Review of the draft evidence report by a peer review panel of 14 experts representing key clinical constituencies and major use organizations approved by AHRQ.
In this section we describe the evidence meeting our inclusion criteria on ventilation management, clinical monitoring and assessment, drug treatment, secretion management, and airway management.
Management of ventilatory insufficiency is the most urgent of pulmonary complications of acute SCI and the issue about which we identified the most empirical literature. Included in this category are interventions to improve ventilatory function or relieve ventilatory insufficiency, among both patients who require mechanical ventilatory assistance and those who do not.
Three studies described how individual patient characteristics could predict which patients would require some type of mechanical ventilatory assistance. Two of these studies described predictors of invasive MV following acute SCI (Claxton, Wong, Chung et al., 1998; Myllynen, Kivioja, Rokkanen et al., 1989) and one described predictors of nocturnal hypoxia in patients with chronic SCI (Cahan, Gothe, Decker et al., 1993).
In a retrospective study of 72 patients with acute cervical SCI, Claxton, Wong, Chung et al. (1998) assessed predictors of MV within 3 months of injury. Of the 72 patients, 15 died and 41 required MV within 3 months. Sixty percent of patients had injuries at C5 or higher, and more than two-thirds of them required MV, compared with only 39 percent of patients with lower-level cervical injuries. In univariable analysis, the predictors of need for MV include injury level C5 or higher, complete lesions, copious sputum in the first week after injury, pneumonia, and lung collapse. In a multivariable analysis, copious sputum and pneumonia proved to be independent predictors of need for MV, while neurological level C5 or above missed statistical significance.
Myllynen, Kivioja, Rokkanen et al. (1989) reported on the rate of various respiratory complications and on predictors of respiratory complications in a retrospective series of 54 patients with acute cervical SCI. The need for ventilatory support during initial intensive care treatment was predicted by the level of cord injury (r = 0.317, p < 0.05) and completeness of cord injury (r = 0.419, p < 0.01), but not by the first values of blood pressure, pulse rate, or blood gas analysis. However, the respiratory rate on admission was associated with having any of the following respiratory complications: atelectasis, pneumonia or other respiratory infection, MV, and pulmonary thromboembolism.
| Clinical Feature | Claxton, Wong, Chung et al. (1998) | Myllynen, Kivioja, Rokkanen et al. (1989) | Branscomb, Stover, DeVivo et al. (1984) |
|---|---|---|---|
| Level of injury C5 or above C6 or below Completeness of injury Complete Incomplete Copious sputum in week 1 Yes No Pneumonia Yes No Major lobe collapse Yes No | 29/42 (69%) 11/28 (39%) p < 0.002 uni; 0. 05 < p < 0.10 multi 28/39 (72%) 4/31 (13%) p = 0.01 uni; NS multi 22/23 (96%) 21/48 (44%) p = 0.001 uni; p < 0.05 multi 30/33 (91%) 10/39 (26%) p = 0.001 uni; NS multi 18/19 (95%) 22/51 (43%) p = 0.0001 uni; NS multi | 19/32 (59%) 8/19 (42%) p = 0.23 uni; p < 0.05 linear p < 0.01 linear Not reported Not reported Not reported | 6/11 (55%) (C4 or above)2/12 (17%) (C5 or below) p = 0.06 Not reported Not reported Not reported Not reported |
Linear = linear regression analysis; multi = multivariable analysis;NS = not significant; uni = univariable analysis.
| Complication | High Cervical Injury (C4 and above) | Low-cervical Injury (C5 and below) |
|---|---|---|
| Atelectasis Pneumonia Pneumothorax Upper respiratory infection Pleural effusion | 5/11 (46%) 2/11 (18%) 1/11 (9%) 2/11 (18%) 1/11 (9%) | 2/12 (17%) 3/12 (25%) 1/12 (8%) 0 0 |
The findings of these studies suggest that patients with higher-level injuries are almost twice as likely to require mechanical ventilatory assistance as those with lower cervical injuries (below C5). Furthermore, patients with complete injuries are much more likely than those with incomplete lesions to require MV, although this is probably important only with high cervical level of injury. The amount of secretions and serious pulmonary infection (pneumonia) are also strongly associated with the need for MV. These findings reinforce the potential for treatments aimed at improving ventilation, cough, and secretion clearance to reduce the need for MV.
The studies we found describing management of mechanical ventilatory assistance after acute cervical SCI were cohort or case series design studies that did not have sufficiently consistent and detailed descriptions of patients, management strategies, or clinical measures to permit comparison among different approaches. However, individually these studies provide potentially useful insights.
Patients requiring MV have a high mortality rate. A large retrospective study described the mortality among 435 patients discharged on a ventilator from a Model Systems rehabilitation center (DeVivo and Ivie, 1995). The study identified patients on admission to a Model Systems facility, often within 1 day post-SCI. For the subgroup of patients admitted within 1 day of SCI, survival was much lower (approximately half) than that of entire cohort of mechanically ventilated Model Systems patients (25.4 percent versus 49.7 percent). Thus, among cohorts or series of patients, survival figures may vary considerably based on whether the high mortality in acute post-injury care is taken into account.
| Level of Injury | n | % |
| C1 C2 C3 C4 C5 C6 C7 C8 T1 and below Total | 68 86 79 79 41 32 11 2 37 435 | 15.6 19.8 18.2 18.2 9.4 7.3 2.4 0.5 8.6 100 |
Carter (1979) and Carter, Donovan, Halstead et al. (1987) (possible overlap with Carter (1993)) reported a case series of 67 patients with high cervical injuries. There were 20 patients with C3-level injuries, all of whom were apneic on admission, although the time since injury for this group was not specified. Over the course of treatment, six patients had a drop in motor level such that they regained spontaneous respiration, with VC ranging from 800 to 2,000 cc; two of them were discharged without the need for ventilatory assistance. Twelve patients required some form of MV at discharge, five of whom used at least part-time EPR.
The authors categorized 47 patients with C4 injuries into two subgroups based on VC at admission above or below 1,000 cc. The 28 patients with VC below 1,000 cc had average VC on admission of 670 cc. During the course of rehabilitation (average of 75 days), the mean improvement in VC for this group was 1,167 cc, and 23 were discharged breathing on their own. Although 23 of the 28 patients with VC less than 1,000 cc on admission were discharged breathing spontaneously, 16 patients required tracheostomy for prolonged mechanical ventilation, and 2 patients died during their rehabilitation stay.
The 19 patients with VC above 1,000 cc had an average VC on admission of 1,550 cc and improved an average of 1,122 cc over an average of a 57-day rehabilitation course. Eight of the 19 patients (42 percent) required tracheostomies. None of the 18 patients who survived required any ventilatory support at the time of discharge. This study also reported that the 1-year mortality had changed dramatically from the 1960s, decreasing from 40 percent for patients treated in the 1963-1969 period to 15 percent in the 1970-1977 interval. This study suggests that VC > 1 L on admission is a favorable prognostic factor for patients with C4 injury.
Patient preferences regarding MV suggest that most would choose to have MV again. Gardner, Theocleous, Watt et al. (1985) surveyed patients with SCI who received MV following acute cervical SCI, and their caregivers. The 37 patients described in this article were also included in the series of 44 patients described in Gardner, Watt, and Krishnan (1986). Most (18 of 21) patients said they would receive MV again if needed, but one wished to have been allowed to die and two were undecided. Most relatives of surviving patients (76 percent) were glad about the decision to use MV, but four of 21 (19 percent) were not. Those four who responded that they were not glad with the decision (to use MV) cited overly burdensome caregiving responsibilities as their reason.
The use of NPPV was described in a series of 14 patients with cervical SCI (Tromans, Mecci, Barrett et al., 1998). The authors used inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure, with a difference of at least 8 cm H2O, cycling spontaneously in response to the patient's own respiration. By the use of NPPV, patients were kept on the spinal cord unit, rather than being transferred to the ICU. Of the 14 patients placed on NPPV, six (43 percent) required intubation for MV within 2 days. The mean VC for these six patients was 583 cc. Eight patients continued on NPPV for an average of 8 days before weaning; their mean VC immediately before commencing NPPV was 875 cc (range 500 to 1,700 cc); however, the difference was not statistically significant (0.05 < p < 0.10). The lack of a clear description of the indication for beginning prophylactic NPPV and the lack of a comparison group randomized to no ventilatory support makes it difficult to evaluate the effectiveness of NPPV in alleviating the need for invasive MV in SCI.
Harvey and Ellis (1996) describe the acute effects of continuous positive airway pressure (CPAP) on pulmonary function, in particular, closing volume and functional residual capacity (FRC) in 10 patients with tetraplegia with levels of injury C4 to C8. They found that 30 minutes of CPAP at 5 cm H2O and 10 cm H2O increased FRC; however, within the first minute after removal of CPAP, FRC returned to baseline values.
We identified 10 studies describing experience with weaning patients with traumatic tetraplegia from MV. The reports varied in terms of the techniques used, the uniformity of techniques or protocols, and the degree of detail provided about the technique. Some reports described a general strategy for weaning, but not detailed protocols. Others described the techniques applied to individual patients, but neither an overall strategy nor detailed criteria for their use.
One report confined itself to assessing the use of electromyography of the diaphragm as a predictor of eventual recovery of respiratory function (Lesoin, Delandsheer, Lozes et al., 1983) among 10 patients on MV. All patients were described as having complete injuries: six had injuries at the C4-C5 levels, and the rest at C6 or below. Electromyographic (EMG) activity was detected in three patients, all of whom eventually recovered respiratory function; however, none of the seven patients in whom electromyographic activity was not detected regained respiratory function. Although the authors of this letter did not statistically analyze these data, the association between EMG activity and recovery of respiratory function is highly statistically significant despite the small sample size (Fisher's exact test, p = 0.0083).
Only two studies provided data comparing two or more weaning techniques (Peterson, Charlifue, Gerhart et al., 1994; Peterson, Barbalata, Brooks et al., 1999) Both studies were retrospective. Peterson, Charlifue, Gerhart et al. (1994), a study which is also described briefly in Peterson, Brooks, Mellick et al. (1977), described the results of 62 separate weaning attempts in patients with C3-C4 level of injuries using either intermittent mandatory ventilation (IMV; 26 attempts) or progressive ventilatory-free breathing (PVFB; 34 attempts). Seventeen patients underwent PVFB weaning attempts after failing IMV. Although the study was not randomized, and a large proportion of patients went sequentially from one method to another, the populations were nearly identical in terms of level of injury, all being C3 or C4. The completeness of injury was not described. The study found that PVFB succeeded significantly more often than did IMV (p = 0.02). The success rates for the two techniques were generally similar during the first 6 weeks (31 percent versus 32 percent). After 8 weeks, further IMV was not successful, but PVFB was successful in weaning several patients. The fact that 17 patients who failed weaning on IMV were then tried on PVFB (and included in the PVFB data) makes the finding of a higher success rate for PVFB more robust.
In a separate report, Peterson, Barbalata, Brooks et al. (1999) described patients with C3 or C4 level of injury who were ventilated and weaned using PVFB. (This was an expanded series including 13 additional patients reported very briefly in Peterson, Brooks, Mellick et al. [1997].) The 1999 study compared patients who were ventilated with a high tidal volume (> 20 mL/kg) versus a low tidal volume (< 20 mL/kg); both groups were ventilated in assist/control mode. Actual tidal volumes ranged from 20.03 to 32.2 mL/kg in the high-volume group and from 11. 6 to 19.4 mL/kg in the low-volume group. The larger tidal volume group weaned more quickly than the low tidal volume group (p = 0.02). The high-volume group also had fewer patients with atelectasis during weaning (3/19 versus 12/23; p = 0.01). The incidence of pneumonia was similar between groups (1/19 versus 3/23; p = 0.39), and there was no significant difference in the need for chest tube placement (1/19 versus 0/23; p = 0.27).
| Study | N | LOI | Success | Partial | Failure | Duration | Method |
|---|---|---|---|---|---|---|---|
| Bach (1991) | 34 | C4 or above | 29% (10) | - | 71% (24) | - | PVFB/NIV |
| Gardner, Watt, and Krishnan (1986) | 44 | 55% C4 or above | 50% (22) | 2% (1) | 39% (17) | - | - |
| Lamid, Ragalie, and Welter (1985) | 13 | 46% C3-C4 | 100% (13) | - | - | - | - |
| Peterson, Barbalata, Brooks et al. (1999) | 23 19 | C3-C4 C3-C4 | 100% 100% | - - | - - | 38 days 59 days | PVFB/High vol A/C PVFB/Low vol A/C |
| Peterson, Charlifue, Gerhart et al. (1994) | 26 34 | C3-C4 C3-C4 | 35% (9) 68% (23) | 19% (5) 18% (6) | 46% (12) 15% (5) | - | SIMV PVFB |
| Sortor (1992) | 22 | 86% C3-C4 | - | 18% (4) | 77% (17) | - | - |
| Splaingard, Frates, Harrison et al. (1983) | 17 | 47% C3-C4 53% C2 or above | 24% (4) | 18% (3) | 59% (10) | - | Not described |
| Tromans, Mecci, Barrett et al. (1998) | 12 | 50% C4 45% C5 or below | 83% (10) | - | 17% (2) | 38 days | NIV (BiPAP®) |
| Viroslav, Rosenblatt, and Tomazevic (1996) | 76 | Not described | 26% (20) | 30% (23) | 43% (33) | - | NIV |
A/C = assist-control; LOI = level of injury; NIV = noninvasive ventilation; NS = not significant; PVFB = progressive ventilator-free breathing; SIMV = synchronized intermittent mandatory ventilation.
The prognosis for patients on MV who survive the initial period of high risk is good. DeVivo and Ivie (1995) described survival in a large cohort of persons with SCI who were dependent on MV at the time of death or discharge from rehabilitation from Model Systems institutions. Among those patients surviving to 1 year, the 15-year survival rate was 61. 4 percent. There was a marked improvement in survival over the last three decades, with persons injured since 1986 having 91 percent lower mortality than persons injured between 1973 and 1979. The single most frequent cause of death in these patients was pneumonia, which accounted for 27.3 percent of deaths of known cause; another 12.3 percent of deaths were attributed to "symptoms and ill-defined conditions" that were always respiratory in nature; "other specific respiratory causes" (not including pulmonary embolism) was the fifth most frequent cause of death, accounting for 6.2 percent of deaths. Altogether, respiratory conditions accounted for 48.9 percent of deaths among ventilator-dependent persons with SCI.
It is hypothesized that chronic ventilator dependence may have significant psychosocial effects for patients with SCI. Bach and Tilton (1994) compared overall life satisfaction, general affect (well-being), and level of distress over ventilator dependence versus distress over loss of extremity function between two groups of patients with complete traumatic tetraplegia (level of injuries not specified) -- 42 on chronic ventilatory assistance and 45 autonomously breathing. The ventilator-assisted patients required a mean of 17.6 hours/day of ventilatory support and had been on ventilation for an average of 9.7 years. The autonomously breathing subjects averaged 8.9 years since injury. The investigators also surveyed a larger group of healthcare professionals (n = 273). Long-term quality of life and well-being was found to be similar in ventilator-dependent and autonomously breathing patients with SCI and was correlated with the degree of family and social interaction. Ratings of quality of life and well-being given by healthcare providers responding as if they were ventilator-assisted were lower than those given by patients with SCI. Ventilatory-assisted subjects rated their distress over their loss of breathing autonomy lower than the autonomously breathing SCI subjects predicted they would. This study suggests that chronic ventilatory support does not result in important decrements in quality of life as is often assumed by non-disabled individuals.
In cervical SCI, NPPV has been described as a technique for temporary support of acute ventilatory insufficiency to avoid intubation (Tromans, Mecci, Barrett et al., 1998), a means to facilitate weaning from invasive ventilation (Tromans, Mecci, Barrett et al., 1998; Bach, 1991; Bach, Alba, and Saporito, 1993) and as a means of providing long-term ventilatory support (Bach, Rajaraman, Ballanger et al., 1998).
One potential advantage of NPPV over tracheostomy positive pressure ventilation (TPPV) may be that it does not bypass the body's mechanisms for filtering inspired air in the oro- and nasopharynx. NPPV has been associated with a lower risk of respiratory tract infection, particularly pneumonia, than TPPV in acute-care hospitals during short-term use. Whether this is true for persons with cervical SCI using the techniques for home ventilation was tested by Bach, Rajaraman, Ballanger et al. (1998). Among 52 persons with SCI on home ventilation, the incidence of pneumonia was lower after transition to part-time or full-time noninvasive ventilation at home than while on PPV through endo- or nasotracheal tube in hospital (p < 0.05). Patients who used tracheostomy PPV at home had no such decrease in incidence of pneumonia. The hospitalization rate for home-managed patients was lower for patients on part-time or full-time noninvasive ventilation compared with those on TPPV (p < 0.05). This study suggests that noninvasive ventilation may reduce the risk of pneumonia compared with tracheostomy interfaces for patients requiring chronic ventilatory support.
Long-term health outcomes associated with CPAP have rarely been described in persons with tetraplegia, with some information reported on suspected nocturnal hypoxemia. Gothe and Maximin described experience with 14 patients with abnormal nocturnal oxygen saturation. Of six patients maintained on CPAP treatment for up to 5 years, all but one had died. The mortality rate was similarly high among the seven who had not been treated with CPAP. The study, reported as a letter, had incomplete followup and was too small to yield meaningful estimates of mortality; however, it does emphasize that nocturnal oxygen desaturation is associated with high mortality.
We identified five separate case series describing data on the effectiveness of EPR for chronic ventilation assistance. In Carter (1993), which may overlap with Carter (1980) and Carter, Donovan, Halstead et al. (1987), this retrospective series compared survival among persons with high-cervical SCI discharged home on mechanical ventilation (n = 19) with those discharged with EPR (n = 23). Phrenic nerve stimulators were implanted an average of 14.6 months after SCI. Assuming four patients lost to followup had actually died, total survival rate after SCI (from contemporary patients) was greater for patients on EPR than for those on IPV. However, these differences were not statistically significant, and, excluding the four patients lost to followup, would yield nearly identical survival rates for the two groups.
The application of EPR from the time of implantation was studied in a small series of 15 ventilator-dependent patients with high-cervical SCI (Fodstad, 1989). After implantation, phrenic nerve pacing began on day 10, with hourly pacing for 3 minutes each hour. These periods of pacing were gradually increased over 2 weeks to 2 months. After a followup of from 2 to 96 months (mean 45 months), five of 15 (33 percent) had ceased EPR pacing and were using no MV support; all of these patients had C3-C5 level of injury. Four (27 percent) used EPR pacing full time with no MV support, and six (40 percent) used EPR during the day and MV support at night.
| Study | Number of Subjects | EPR Use at Followup | Mortality | Followup, Mean (mo.) | |||
| Off all MV | Full-time | Part-time | Failed | ||||
| Carter (1993) | 23 | - | - | - | - | 39% (9) | 88.7 |
| Fodstad (1989) | 15 | 33% (5) | 27% (4) | 40% (6) | - | 0% (0) | 45 |
| Glenn, Holcomb, Shaw et al. (1976) | 37 | 0 | 35% (13) | 27% (10) | 38% (14) | 27% (10) | 26 |
| Miller, Farmer, Stuart et al. (1990) | 23 | 0 | 35% (8) | 52% (12) | 13% (3) | 9% (2) | 12 |
| Weese-Mayer, Silvestri, Kenny et al. (1996) | 29 | 0 | - | 86% (25) | 14% (4) | 3% (1) | 26 |
EPR = electrophrenic respiration; MV = mechanical ventilation.
| Study | Number of Subjects | Receiver Failure | Electrode Failure | Local Infection | Phrenic Nerve Trauma |
|---|---|---|---|---|---|
| Glenn, Holcomb, Shaw et al. (1976) | 37 | "common" | "uncommon" | 14% (5) | 30% (11) |
| Weese-Mayer, Silvestri, Kenny et al. (1996) | 29 | 10% (3) | 7% (2) | 0% (0) | 10% (3) |
| Fodstadt (1989) | 15 | "common" | - | - | - |
| Miller, Farmer, Stuart et al. (1990) | 23 | 13% (3) | - | - | - |
EPR = electrophrenic respiration.
The incidence of complications associated with EPR is described in one of these studies (Weese-Mayer, Silvestri, Kenny et al., 1996). Complications over an average of 2.2 years included equipment-related and nonequipment-related complications. Equipment-related complications included mechanical trauma to the phrenic nerves in 3/29 patients (10 percent) and flutter of the diaphragm in one (3 percent). No patients in this series had infection. Nonequipment-related complications included electrode failures in two (7 percent), receiver failures in three (10 percent), and nonfunctioning electrode combinations in nine episodes in five patients (17 percent). Altogether, 25 patients were successfully paced in this study, but only 15 (52 percent) were successfully paced and had no complications.
Miller, Thomas, and Wilmot (1988) described their experience in the use of the pneumobelt among patients with cervical SCI. Twenty-one patients were selected to try to use the pneumobelt based on their ability to sit up at 90 degrees and breathe room air. Seventy-one percent of the patients had C3- or higher-level injuries. The patients were an average of 3 to 6 months post-injury. During inpatient rehabilitation, most patients (12/21 [57 percent]) were able to use the pneumobelt for 4 or more hours per day, and another eight patients used it for an average of between 2 and 4 hours daily. One patient complained of abdominal discomfort and was unable to tolerate the technique. The authors gathered limited followup data on the patients who had been discharged (n = 13). Eleven of the 13 (85 percent) were still using a pneumobelt at the time of discharge. Ten respondents to a post-discharge survey all reported a "high level of satisfaction" with the device. The pneumobelt has also been demonstrated to be feasible in a regimen of 24-hour noninvasive ventilatory support in a large series of patients with neuromuscular diseases (Bach and Alba, 1991).
Empirical studies of the effects of a variety of physical interventions on pulmonary function in patients with cervical SCI demonstrate effects of respiratory muscle conditioning; GPB; and changes in head, neck, and body position or posture.
The VC of patients with cervical SCI is reduced, and the severity of this reduction varies with several factors, the most important being the level of injury. Supine VC among patients with low-cervical injuries who are able to breathe on their own was reduced to about half of predicted normal values.
| Study | LOI | Design | Baseline VC | Interventions | Findings | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Lane (1982) | NS | Prosp. series | NS | Abdominal weight training | Improved FVC before to after training | ||||||
| Derrickson, Ciesla, Simpson et al. (1992) | C4-C7 Acute | RCT | 1.3 L | Inspiratory resistance training versus abdominal weight training | Both groups improved in all spirometric parameters; no difference between active and control | ||||||
| Huldtgren, Fugl-Meyer, Jonasson et al. (1980) | C4-C8 Chronic | Prosp. series | 42% ppv | Insufflation and inspiratory resistance training | Improvement in TLC, VC, ERV, Pemax, Pimax | ||||||
| Walker and Cooney (1987) | C4-C8 Chronic | Prosp. series | 2.6 L | Incentive spirometry and arm ergometer exercise | 25% improvement in VC 70% improvement in max VE | ||||||
| Loveridge, Badour, and Dubo (1989) | C6-C7 Chronic | RCT | 68% ppv | Inspiratory resistance training versus control | Both groups improved in all spirometric parameters; no difference between active and control | ||||||
| Cheshire and Flack (1978) | C4 MV C4-C6 acute C5-C6 chronic | Prosp. series | 0.37 L 1. 63 L 1. 3 L | Incentive spirometry | Improvement in FVC
| ||||||
| DiPasquale (1986) | C1-C4 | Case series | NS | Deep breathing exercises and glossopharyngeal breathing along with education | Average improvement in VC of 0.5 L per patient |
ERV = expiratory reserve volume; FVC = forced vital capacity; L = liters; LOI = level of injury; MV = mechanical ventilation; NS = not significant; ppv = percent predicted value;Pemax = maximum expiratory pressure;Pimax = maximum inspiratory pressure; prosp. = prospective; RCT = randomized controlled trial; TLC = total lung capacity; VE = expired unit per volume time.
In a retrospective study, Lane (1982) demonstrated statistically significant increases in FVC among 16 patients with tetraplegia who received abdominal weight training three times per week for 6 weeks, compared with 15 patients who had routine physical therapy management. In that study, patients with C4 level of injury made slower improvement in FVC than did patients with lower-level injuries (C5).
Derrickson, Ciesla, Simpson et al. (1992) conducted a randomized controlled trial among patients with recent low-cervical SCI comparing two types of exercise: inspiratory resistive muscle training versus abdominal weights. All patients were breathing on their own, although some had only just been weaned from MV. Baseline spirometric values revealed a mean FVC of 1.3 L. Forty-five percent of patients had a C4-C5-level injury, while 18 percent had C6- and 36 percent had C7-level injuries. Patients in both groups received two 15-minute training sessions per day, 5 days per week, for 7 weeks. All patients improved in all spirometric indices, including FVC, maximal voluntary ventilation (MVV), peak expiratory flow rate (PEFR), maximum inspiratory pressure (Pimax), and inspiratory capacity (IC). However, no differences were observed between the two exercise conditions; similar improvements in pulmonary function measures were observed for both types of breathing exercise.
Huldtgren, Fugl-Meyer, Jonasson et al. (1980) reported the results of an uncontrolled prospective trial of a respiratory training program that included insufflation and resistance training among 12 patients with tetraplegia (level of injury C4 and below). All patients were breathing on their own. Insufflation of air into the lungs using a manually operated pump was performed 10 times daily in supine patients with abdominal binders. The insufflated volume was increased every other day until predicted total lung capacity (TLC) was achieved. Resistance training included forced expiration and inspiration against resistance starting at spontaneous TLC, and in separate attempts starting at a higher lung volume following insufflation (insufflated TLC). After 6 weeks of training, patients showed significant improvement in VC, expiratory reserve volume (ERV), Pimax, and maximum expiratory pressure (Pemax). Followup of 11 patients at 1 year and five patients at 5 years suggests that the lung volumes remained improved, although improvements in static respiratory pressures were not maintained.
Walker and Cooney (1987) prospectively studied the effect of incentive spirometry and arm ergometer exercise in 15 patients with chronic low-cervical SCI. The mean VC at the start of the trial was 2.6 L. By the end of the training program, the VC had increased by 25 percent, or 0.66 L, and expiratory volume had increased by 70 percent.
Loveridge, Badour, and Dubo (1989) conducted a randomized controlled trial comparing inspiratory resistive muscle training with control among 12 patients with chronic C6-C7-level injuries. The training, described as ventilatory muscle endurance training, consisted of using an inspiratory resistor twice daily for 15 minutes, 5 days per week, for 8 weeks. The resistance was equivalent to 85 percent of sustained inspiratory mouth pressure (SIP), and was increased as SIP increased. Both the exercise and control groups showed improvement in maximum inspiratory mouth pressure and SIP, and although improvements were somewhat greater in the training group, they were not statistically significantly greater than in the control group.
Incentive spirometry may be used to improve respiratory muscle function in patients on ventilatory support in preparation for weaning, or in autonomously breathing patients. Cheshire and Flack (1978) described the use of an incentive spirometry program involving the Spirocare Incentive Breathing Exerciser, a spirometer with flashing colored lights rather than numbers to more clearly indicate success to the patient. Twelve patients in the study included five on MV; five with recent injury, but who did not require MV; and two with old SCI injuries who were recovering from an acute respiratory illness. Patients in all groups improved FVC, although no control group was assessed.
Another series described the use of a multidisciplinary intervention of respiratory muscle exercise and grouped educational sessions among 56 patients with high-cervical SCI, nearly all of whom were ventilator dependent (DiPasquale, 1986). Both respiratory (GPB) and nonrespiratory (head and neck motion and passive range of motion to upper extremities) exercises were included. The program resulted in an average 0.5 L improvement in VC, although neither baseline VC nor time since injury was described.
Glossopharyngeal breathing (GPB) is a technique in which a patient uses the muscles of the mouth, pharynx, and larynx to add to inspiration by pushing (gulping) boluses of air past the glottis. The glottis closes after each gulp. It requires training, but can be used autonomously by patients to augment VC to provide for improved cough or to allow prolonged ventilator-free time even in patients with minimal spontaneous VC.
Montero, Feldman, and Montero (1967) assessed the effect of training in GPB among 14 patients with low-cervical SCI. Instruction was given for one-half to 1 hour three times weekly until each patient could increase his VC by 0.7 to 1 L with 10 to 20 GPB "gulps." The patient practiced unsupervised for 10 minutes two to three times daily. Pulmonary function tests after training showed improvements in mean VC from 35 percent predicted normal to 65 percent predicted normal. Similar improvements were seen in peak expiratory flow (PEF), MVV, and breath-holding time. Furthermore, the authors observed that GPB allowed improvements in audibility of patients' voices, such that they could call out more loudly than they had been able to before receiving training.
| Study | Level of Injury | Mean VC in Supine Position | Effect of Changing from Supine to Sitting Position on VC | P-value |
|---|---|---|---|---|
| Fugl-Meyer (1971) | 4% C4 96% C5-C8 | 42% predicted | Reduced 28% | p < 0.001 |
| Forner, Llombart, and Valledor (1977) | 25% C4 or C5 75% C6 or below | 50% predicted (sitting) | Reduced 11% | p < 0.05 |
| Chen, Lien, and Wu (1990) | C4-C8 | 57.1% predicted | Reduced 11% to 13% predicted | p < 0.05 |
| Estenne and De Troyer (1987) | 21% C4-C5 or C5 50% C5-6 or C6 29% C6-C7 or C7 | 48.4% predicted | Reduced 16% of seated values or 0.41 L | - |
| Maeda, Baydur, Waters et al. (1990) | 40% C5 50% C6 or below | 65.3% predicted | Reduced 8% predicted | p = 0.015 |
VC = vital capacity.
Estenne and De Troyer (1987) replicated the effect of changes in position among 14 persons with chronic cervical SCI. In addition, they tested whether the use of leg cuffs or abdominal binding could reduce the postural effects on VC. Inflating blood pressure cuffs at the base of a subject's legs (up to diastolic blood pressure) before he assumed a seated position had little effect on residual volume (RV) or VC. Abdominal binding using elastic straps was fitted while subjects were supine and at end expiration. Abdominal binding eliminated the increase in RV that occurred when subjects assumed a seated position.
This study suggested that the mechanism of the postural dependence of VC in persons with tetraplegia is a reduction in ERV rather than mechanical advantage of the diaphragm, as had been previously supposed. This study suggests that the effect of gravity (and posture) on the abdominal contents and diaphragm, and hence on VC, can be partially overcome through the use of abdominal binding.
Several more-recent smaller studies have addressed further questions regarding positioning. Amodie-Storey, Nash, Roussell et al. (1996) assessed the head position of 15 persons with cervical SCI, classifying each subject in terms of habitual head posture: forward and not forward. Forward orthostatic position of the head was defined as a more than 6-cm forward displacement of the midcervical spine relative to the thoracic spine when seated. By using rolled towels, investigators were able to alter the habitual posture, so that the three subjects with not-forward head posture were positioned to be forward, and the 12 who were habitually forward were placed in the not-forward position. A variety of spirometric indices were measured, with each subject in his habitual posture and in the experimental altered posture. For the 12 subjects with habitual forward posture, FVC and MVV were significantly lower in the altered than in the habitual posture, with a mean reduction of about 8.5 percent in FVC (p < 0.05) and 14.5 percent in MVV (p < 0.05). Among the three subjects with the not-forward habitual posture, slight reductions in FVC and MVV were not statistically significant. No significant changes were observed for forced inspiratory vital capacity (FIVC) or forced expiratory flow between 25 and 75 percent of the exhaled volume (FEF25-75) in either group. These findings suggest that altering the orthostatic head position may result in reduction of pulmonary function.
Halo vests are often used to stabilize the cervical spine following acute SCI. A previous retrospective study found that the halo vest restricted the VC by 8 percent in both quadriplegic and neurologically intact patients (Lind, Bake, Lundqvist et al., 1987). Maeda, Baydur, Waters et al. (1990) prospectively investigated the effects of body position and halo vest on VC in patients with tetraplegia compared with neurologically intact patients. Changes in position from supine to sitting resulted in similar decreases in VC with or without halo vest. The application of the halo vest itself reduced the VC by 6 percent predicted in the supine position (p = 0.01) and by 2.5 percent predicted in the sitting position (p = NS). A control group of neurologically intact subjects showed no decrement in VC from supine to seated, but did show a slightly greater percentage decline in VC with application of the halo vest. Because their pulmonary function was normal, this decrement was not clinically important.
Ventilatory function is often assessed frequently among patients with acute cervical SCI, typically every 8 hours. Studies that document improvement over time or with respiratory muscle conditions suggest that serial testing may be indicated, although we found no studies that help to determine the optimal timing or frequency of such assessment. Several studies are relevant to how such assessments should be performed. Studies of the effect of posture and positioning on PFTs (discussed in the preceding Posture section) indicate that spirometric tests in the usual seated position give a systematically lower value for FVC when compared to the supine position. Choice of position for testing should depend on patients' functional position.
To meet American Thoracic Society (ATS) criteria for acceptability and reproducibility of FVC and forced expiratory volume in 1 second (FEV1) measures, patients must obtain at least three acceptable efforts, which require an exhalation time of at least 6 seconds, no nasal or mouth leaks, cough or other problems, and maximal effort as judged by the technician. However, patients with cervical SCI often fail to meet the requirements for acceptability or reproducibility. They have a relatively long transition time from forceful inhalation to forceful exhalation, which causes difficulty determining the starting time for calculating the FEV1. The extrapolation of the starting time leads to an estimate of the volume of air expired that was not measured -- the extrapolated back expiratory volume (EBEV). To be acceptable, the EBEV can be no more than 5 percent of FVC or 100 cc. Ashba, Garshick Tun et al. (1993) described the proportion of patients who could perform acceptable and reproducible spirometry according to the ATS definition and two less-stringent criteria. One less-stringent criteria required two, rather than three, acceptable efforts and allowed a larger EBEV if effort appeared to be maximal. The other modification included the above modifications and also allowed exhalation times of less than 6 seconds so long as a plateau of at least 0.5 seconds had been reached. Two-thirds of subjects had a least two acceptable efforts according to the standard ATS criteria, but 11 of 12 (92 percent of subjects) had two or more acceptable efforts with either modification. Similarly, the modified criteria increased the reproducibility from 58 percent to 83 percent for FVC and from 50 percent to 75 percent for FEV1.
The neurological examination for limb muscle strength and tone may be relevant to the assessment of pulmonary function. Roth, Lu, Primack et al. (1997) correlated neurological exam (muscle strength and tone) with PFTs in 44 patients with cervical SCI at the C4 level or lower at an average of 77 days after injury. Muscle tone was measured using the Ashworth scale, which rates the severity of limb spasticity (Ashworth, 1964). The 52 patients described in this article are the same as those described in Roth, Nussbaum, Berkowitz et al. (1995). The muscle strength was measured directly in the limbs. The authors found that the level of injury was significantly correlated with negative inspiratory pressure and estimated reserve volume, but not with most other PFT measures, primarily measures of expiration. Only negative inspiratory pressure was significantly correlated with muscle-tone ratings. The authors concluded that muscle strength may be a more important factor than muscle tone in determining pulmonary function in persons with SCI, and that both strength and tone are closely related to negative inspiratory pressure. However, the narrow spectrum of level of injuries, with all but a few patients in the range from C4 to C7, may have diminished their ability to demonstrate differences.
Chest roentgenography often demonstrates pulmonary lesions in patients with tetraplegia. Available studies do not clarify the significance of these lesions. A retrospective case series reported by Scher (1982) found that 28 percent of all patients (14 of 50) had chest lesions visible on chest roentgenography. The chest X-rays were taken during a period of stable symptoms and at least 12 weeks after SCI. Patients with neurologically complete lesions had a higher rate of chest roentgenogram (CXR) abnormality (40 percent; 12 of 30) than those with incomplete lesions (10 percent; two of 20). The age and significance of these lesions were not specified.
Another retrospective study described pulmonary injuries that had been undetected in the initial assessment of patients with acute SCI. Ryan, Klein, and Bongard (1993) conducted a chart review on 13 patients with cervical SCI in order to identify those who had injuries overlooked at admission. Six of the 13 patients had injuries that were overlooked; three of these were pulmonary (two pneumothoraces, one paralyzed hemidiaphragm). This study did not describe in detail the sort of clinical assessment that did lead to diagnosis of these conditions, but the high prevalence of pulmonary complications in tetraplegia suggests that CXR in the post-acute period may be warranted.
Two further studies describe the accuracy of roentgenographic procedures (Bain, Bodley, Jamous et al., 1995; Hsu, Dreisbach, Charlifue et al., 1987). Bain, Bodley, Jamous et al. (1995) described the agreement between CXR and chest computed tomography (CT) among 60 patients with SCI who had both procedures. Supine CXR was assessed blind to CT findings, and parenchymal abnormalities were identified. Effusions were classified as small, medium, or large, according to stated criteria. CT results were correlated with the CXR. Absolute agreement occurred in 20 percent (12 of 60). CXR underestimated the changes demonstrated on CT (either failed to diagnose it or rated its size differently by more than 1 degree) in 58 percent (35 of 60). In 22 percent (12 of 60), CXR overestimated the changes demonstrated on CT. This study points out that pleural effusions are frequently missed by supine CXR. The study shows pleural effusions are common among persons with SCI even when CXR is normal.
Glottic and subglottic tracheal stenosis is diagnosed and treated by endoscopy, but noninvasive tests such as tomography and CTs could be used to diagnose it and grade its severity. In a retrospective case series of 47 patients with SCI, Hsu, Dreisbach, Charlifue et al. (1987) compared tomography and CT scan for effectiveness in grading the severity of stenosis, comparing both against a reference standard of endoscopy. The severity of stenosis was graded as mild (< 20 percent stenosis), moderate (20 to 49 percent stenosis), severe (50 to 79 percent stenosis), or obstruction (80 percent or higher stenosis). Of the 47 patients, 10 had only glottic stenosis, 19 had only tracheal stenosis, and 18 had both glottic and tracheal stenosis. In diagnosing glottic stenosis, tomography agreed with endoscopy in one-third of cases (nine of 27) and was within one grade of severity in another half of cases. CT scan showed greater agreement with endoscopy, with exact agreement in 69 percent and an additional 25 percent within one severity grade. For grading the severity of tracheal stenosis, tomography agreed with endoscopy in 67 percent of cases and agreed within one severity grade in an additional 25 percent. CT agreed with endoscopy in 73 percent exactly, and another 18 percent within one severity grade. Thus, tomography had better agreement with endoscopy for tracheal than glottic stenosis. CT was more accurate than tomography for diagnosing glottic stenosis, but similarly accurate for grading the severity of tracheal stenosis.
Cahan, Gothe, Decker et al. (1993) studied the occurrence of nocturnal hypoxia in a group of persons with tetraplegia who were an average of 14 years post-injury and who had lesion levels of C4 or below. None of the clinical data considered -- including level of injury, age, duration since injury, medications, history of snoring, daytime drowsiness, or acute respiratory illness -- could distinguish between the six persons with nocturnal cyclical desaturation of more than 4 percent in SaO2 (arterial oxygen saturation) and the 10 persons with normal SaO2 values while awake and asleep. Even the combination of snoring and daytime drowsiness, often indications for nocturnal polysomnography in non-SCI persons, did not distinguish hypoxic from normal subjects. This study suggests that clinical history may not be a reliable indicator of the risk for sleep-disordered breathing among persons with cervical SCI.
Swallowing disorders can predispose a person with SCI to aspiration, increasing the risk of airway obstruction, atelectasis, pneumonitis, and pneumonia. The prevalence of swallowing disorders in persons with cervical SCI was described in a recently published study of a bedside swallowing evaluation in 187 patients with acute traumatic spinal cord injury admitted to a rehabilitation hospital (Kirshblum, Johnston, Brown et al., 1999). The bedside evaluation consisted of a test of oral-motor strength, range of motion of the tongue and lips, ability to swallow on command, a dry swallow, trial swallow with solids and liquids, and/or a swallow with adjusting of the position of the head as tolerated. Forty-two (22.5 percent) had signs or symptoms detected on bedside evaluation that were suggestive of dysphagia (delay in initiation of the swallow, wet voice quality, or frank coughing). These patients underwent a videofluoroscopic swallowing study (VFSS). VFSS was considered positive if it demonstrated poor pharyngeal stripping action, sluggish or inefficient opening of the cricopharyngeus, excessive pooling in the piriform sinus, delayed laryngeal elevation, or frank penetration or aspiration. VFSS was positive in 73.8 percent (31 of 42). Among the 42 patients with a positive bedside evaluation, patients with dysphagia by VFSS could be distinguished from those without dysphasia by VFSS with three independent predictors: history of spinal surgery via anterior cervical approach (p < 0.016), tracheostomy with mechanical ventilation (p < 0.01), and older age (p<0.028). Higher level of injury and increased time between injury and rehabilitation admission slightly increased the likelihood of dysphagia. Tracheostomy at admission was the strongest single predictor of dysphagia. Patients with both tracheostomy and anterior surgical approach were highly likely to demonstrate dysphagia (48%). However, the authors caution that none of the predictors is strong enough to obviate the need for testing.
It has been suggested that bronchoconstriction is an under-recognized cause of feelings of breathlessness reported by a majority of patients with tetraplegia (Spungen, Grimm, Lesser et al., 1997). Cervical spinal cord transection interrupts the sympathetic nerve supply to the lungs (T1 to T6), but not the parasympathetic innervation, suggesting that unopposed cholinergic tone, which causes hypotension and bradycardia, may also cause bronchial smooth muscle constriction and airway obstruction. Such bronchoconstriction would be potentially treatable with bronchodilating drugs. Perhaps because the restrictive ventilatory impairment among patients with tetraplegia is so severe, less attention has been given to bronchoconstriction and the potential benefit of its treatment. However, we identified a series of studies by the same group of investigators that examines the effects of drug treatments (metaproterenol sulfate, ipratropium bromide, baclofen, oxybutynin chloride) on airway reactivity in patients with SCI. We found no studies of theophylline or other methylxanthines in this population.
Spungen, Dicpinigaitis, Almenoff et al. (1993) and Almenoff, Alexander, Spungen et al. (1995) document that among persons with tetraplegia without acute pulmonary symptoms, nearly half "respond" to inhaled bronchodilators with metaproterenol sulfate (Spungen, Dicpinigaitis, Almenoff et al., 1993) or ipratropium bromide (Almenoff, Alexander, Spungen et al., 1995). Subjects in these studies were all patients with tetraplegia who were able to breathe on their own. Patients with a history of asthma or allergies were excluded. In one study, 28 percent of subjects had chronic dyspnea at rest, but none had evidence of respiratory tract infections or other acute pulmonary symptoms (Almenoff, Alexander, Spungen et al., 1995).
Forty-one percent of patients treated with metaproterenol sulfate (0.6 percent) and 48 percent of patients treated with ipratropium bromide (four puffs inhaled via a spacer device) showed at least 12 percent improvement in FEV1 from pre- to post-bronchodilator. The mean improvement in FEV1 for responders was about 16 percent, whereas non-responders had a mean change of less than 1 percent. This evidence was observed in similar proportions of smoking and non-smoking patients; it was also seen in similar proportions of patients who either did or did not feel dyspneic.
Given this evidence of airway obstruction in a large proportion of patients with tetraplegia, five additional studies were designed using an experimental model of pharmacologically induced bronchoconstriction. The investigators administered increasing doses of methacholine or histamine to induce sufficient bronchoconstriction to reduce the FEV1 by 20 percent (PC20) to measure whether acute (metaproterenol sulfate, ipratropium bromide) and chronic (baclofen, oxybutynin chloride) drug treatments could modify this bronchoconstriction. Baclofen and oxybutynin chloride are GABA-agonists often used to treat spasticity in persons with SCI and have also been shown to inhibit bronchial hyperreactivity, presumably through gamma-aminobutyric acid receptors in the lung.
The first of these challenge studies compared the bronchial response to provocation with methacholine in six patients on chronic baclofen treatment with an eight-patient control group who had not taken baclofen (Dicpinigaitis, Spungen, Bauman et al., 1994). The mean concentration of methacholine required to induce bronchoconstriction was significantly higher for the chronic baclofen group than the non-baclofen group. However, this study could not determine whether the action of baclofen was related to its anticholinergic effect or to a direct effect on airway smooth muscle.
A subsequent study again compared patients who took baclofen chronically to those who did not, but investigators used histamine to experimentally provoke bronchoconstriction (Grimm, DeLuca, Lesser et al., 1997). In this study, there was no difference in PC20 between the baclofen-treated and nonbaclofen-treated patients. Because bronchoconstriction was induced by histamine in both baclofen and nonbaclofen-treated patients, the authors concluded that baclofen was not causing a generalized bronchial smooth muscle relaxation, but exerting a bronchodilator response through its anticholinergic activity. Thus the authors questioned their hypothesis of bronchoconstriction due to unopposed cholinergic tone, in favor of a nonspecific airway hyperresponsiveness, such as that seen in asthma. Presumably this would occur through chronic bronchial inflammation leading to thickening of epithelial, smooth muscle, and adventitial layers.
Subsequently, the same group compared patients who took oxybutynin chloride (Ditropan®) chronically with those who did not and measured experimentally provoked bronchoconstriction response to both methacholine and histamine (Singas, Grimm, Almenoff et al., 1999). Oxybutynin is widely used to treat urinary tract and gastrointestinal spasmodic disorders through its local anesthetic and moderate anticholinergic properties.
Just as in the baclofen studies described above, the oxybutynin-treated patients had much less response to methacholine than did the control patients, whereas both groups responded similarly to histamine. The authors concluded that like baclofen, oxybutynin acts primarily through anticholinergic pathways rather than by causing generalized airway smooth muscle relaxation. Two other studies investigated the potential therapeutic role for acute bronchodilating drugs ipratropium (Fein, Grimm, Lesser et al., 1998) and metaproterenol sulfate (DeLuca, Grimm, Lesser et al., 1999). Fifteen patients with tetraplegia were tested for histamine induced-bronchoconstriction before and after pretreatment with inhaled ipratropium bromide via metered dose inhaler with spacer device. Eighty percent of patients had a significant response to histamine (defined as PC20< 8 mg/mL), and this was unchanged with ipratropium pretreatment. In contrast, in a separate study of 25 subjects with tetraplegia, all of whom had previously demonstrated airway hyperreactivity to methacholine or histamine, metaproterenol sulfate pretreatment showed a different effect on airway hyperreactivity (Fein, Grimm, Lesser et al., 1998). When subjects were pretreated with metaproterenol, the methacholine- and histamine-induced bronchoconstriction was reduced significantly, with a reduction in the geometric mean PC20 of approximately 20 percent.
Thus, metaproterenol, but not ipratropium, can reduce airway hyperreactivity related to either cholinergic activity or non-specific causes. These studies suggest a potential therapeutic benefit from long-term prophylactic therapy with inhaled beta-agonists to reduce symptoms of breathlessness associated with airway reactivity in patients with tetraplegic. However, none of these studies evaluated the long-term efficacy of this or other drug treatments on symptoms, pulmonary function, or on the incidence of pulmonary complications.
Empirical studies relating to the effectiveness of the vaccinations for respiratory infections in tetraplegic patients is limited to two studies describing the antibody response to 23-valent pneumococcal polysaccharide vaccine in populations with SCI (Darouiche, Groover, Rowland et al., 1993; Waites, Canupp, Edwards et al., 1998). We found no studies of the effectiveness of influenza vaccines in this population. Darouiche, Groover, Rowland et al (1993) studied 40 patients with SCI, about half within 1 year of injury and about half with tetraplegia, who were administered the pneumococcal vaccine. The antibody response was compared with that of 40 age-matched, able-bodied controls. Measured at 4 to 6 weeks post-vaccination, the immune responses to five pneumococcal polysaccharides (3, 4, 6A, 8, and 23) were no different between the SCI and control groups. The overall response rates were 78 percent for patients with SCI and 84 percent for controls; these rates are not statistically significantly different. Furthermore, among patients with SCI the antibody response was not affected by age, time since injury, or level of injury. Adverse reactions to vaccination were as expected; approximately one-third of all subjects had transient mild pain or erythema at the site of vaccine injection.
Subsequently, a randomized controlled trial described antibody response to pneumococcal vaccine among 87 patients with SCI (Waites, Canupp, Edwards et al., 1998). The study included patients with acute injury who were randomized, stratified by level of injury, to receive vaccine or placebo 16 to 18 days post-injury. Separately randomized were patients with older injuries who received the vaccine 4 to 6 months after injury. Ninety-five percent of patients receiving the vaccine, compared with 35 percent of the placebo group, developed an immune response at 2 months to at least one serotype of the five tested:3, 4, 14, 19F, and 23F (p < 0.01). At 12 months, 93 percent of vaccine patients maintained a two-fold increase in antibody concentration to one or more serotypes. The timing of vaccination (16 to 18 days versus 4 to 6 months) did not influence mean antibody concentrations.
These studies show that patients with SCI demonstrate a good antibody response to pneumococcal vaccine regardless of whether it is administered soon after injury or later. However, because of differences in pulmonary pathophysiology in patients with SCI, it is uncertain whether the antibody response would be effective in decreasing the incidence of pneumococcal pneumonia or consequences of pneumonia, such as mortality.
Other potentially therapeutic drug treatments have been tested for salutary effects on ventilatory muscle function: hyperbaric oxygen, anabolic steroids, and 4-aminopyridine. We identified a single trial of the effect of hyperbaric oxygen (HBO) on VC among patients with tetraplegia (Hart, Strauss, and Riker, 1984). Patients, described as "fully rehabilitated" and "in the chronic phase of their injury," were an average of 16 months (range 4 to 84) post-injury. Subjects were treated with hyperbaric oxygen at 2 Alimentary Toxic Aleukia for 2 hours daily for 21 consecutive days. At baseline, mean VC was 2.38 L, or 47 percent predicted normal; post-HBO VC was 2.6 L, or 51 percent predicted normal. The pre- to post-treatment values were not statistically significantly different. A secondary analysis rated each patient's change in VC as improved, no change, or decreased, but did not account for test-retest reliability by stating a threshold for what is a clinically important change. In a secondary analysis, investigators reported the number of patients who improved by at least more than 10 percent of their baseline value; however, according to the ATS guideline for spirometry, for measures separated by weeks, this does not exceed the test-retest variability (ATS, 1991). The investigators reported that 10/22 patients had at least 10 percent improvement in VC. The lack of a control group, coupled with a threshold for improvement that falls below the discriminatory ability of serial VC measurement, sheds important doubt on the authors' conclusions that HBO leads to an increase in VC.
Anabolic steroids have been used to increase muscle mass and improve muscle performance in a variety of clinical situations. Limited evidence is available on their effect on pulmonary function in SCI. In a small (n = 10) uncontrolled case series, Spungen, Grimm, Strakhan et al. (1999) studied the oral anabolic steroid oxandrolone. The drug was associated with an average 2 percent weight gain (1.4 ± 1.5 kg) (p = 0.01) after 1 month. Spirometric measures also improved significantly, with FVC increasing from a baseline of 2.8 L to 3 L at 1 month (p < 0.005). Improvement was noted on other spirometric measures, including both inspiratory (FIVC and forced inspiratory volume in 1 second [FIV1]) and expiratory (FVC, FEV1, FEF 25-75, and PEF) measures. The improvement in spirometric measures was associated with an improvement in subjective symptoms of resting dyspnea (p < 0.05). The study found slight increases in serum liver function and lipoprotein tests that did not exceed normal values. No other adverse events were mentioned in the report; however, the study was not designed to detect long-term complications.
The drug 4-aminopyridine is a potassium channel blocker that can enhance nerve conduction in demyelinated neurons. Several reports suggest that it can enhance motor or sensory function in persons with SCI. We found one study that assessed whether a single dose improved pulmonary function in persons with SCI. In Segal and Brunnemann (1997), 11 subjects with cervical-level injuries were treated with an oral dose of 10 mg of 4-AP. Baseline spirometric measures were compared with repeat spirometry performed at 4, 6, 8, 10, 12, and 24 hours. Accounting for the repeated measures taken, the analysis showed that there were statistically significant improvements in each measure from baseline to each patient's maximum measure. Furthermore, the magnitude of these changes exceeded ATS guidelines for clinically significant effects. This study is limited by its single-dose design; the effectiveness over time with continued therapy was not demonstrated in this study.
We identified three studies of rotating beds conducted among patients with cervical SCI. One was a case series with no comparison group (Green, Green, and Klose, 1980), and two compared patients treated on a rotating bed with a historical cohort of similar patients at the same institution before the rotating bed was used (Borkowski, 1989; Lemons and Wagner, 1994). Green, Green, and Klose (1980) reported the incidence of cardiopulmonary complications among a series of 105 patients with SCI (90 percent with tetraplegia) who were treated with a Roto-Rest bed. Seven of 95 patients with cervical SCI had complications, which, the authors report, is a lower rate than that reported in previous series. In calculating this figure, pulmonary emboli were counted among the various cardiopulmonary complications, which were not detailed. The authors concluded that rotating beds reduced cardiopulmonary complications and suggested that the main effect was on reducing venous stasis.
Borkowski (1989) studied the effectiveness of a kinetic treatment table (KTT) compared with a wedge turning device (WTD) for reducing pulmonary complications in an ICU. A historical cohort of 11 patients with SCI who were treated with WTD was compared with a nonconcurrent series of 11 patients treated with the newer KTT. Fifty-nine percent of all patients had cervical injuries, and these were evenly divided between groups. KTT was associated with a lower incidence of pulmonary infection (p < 0.05) and less time on MV (p < 0.05). The rate of endotracheal intubation and tracheostomy were also lower for KTT-treated versus WTD-treated patients, although not significantly so. There were no significant differences in length of ICU stay or hospitalization.
Lemons and Wagner (1994) compared outcomes among 63 patients with cervical SCI after the use of chest physical therapy and rotating beds was added to the standardized respiratory therapy protocol followed at their institution. Most of the patients (63 percent) had C4-C5 level injuries; 37 percent had C6-T1 level injuries. Thirty-nine of the 63 patients developed respiratory complications and 31 required MV. Slight differences favored the later cohort (treated with rotating bed and chest physiotherapy) in incidence of pneumonia (p = 0.043) and length of ICU stay (p = 0.032). However, there were no significant differences in the incidence or duration of respiratory insufficiency (p > 0.5).
In summary, two studies with historical controls suggest that use of rotating beds may decrease the risk of pneumonia and length of ICU stay. Whether this effect is obtained through improved mobilization and clearance of secretions or by reduction of atelectasis is uncertain.
Among patients with SCI, the ability to cough is impaired. The most important cause of impaired cough is the paralysis of the abdominal muscles. In neurologically intact subjects, the peak air flow during volitional cough is between 300 and 700 L/min; in contrast, peak air flow in tetraplegia has been estimated at 220 L/min (Braun, Giovannoni, and O'Connor, 1984). However, this average value is widely variable between subjects and also varies with level of injury (Wang, Jaeger, Yarkony et al., 1997). Several approaches have been used to assist cough, including manual pressure applied to the abdomen (timed with a patient's cough effort), positive pressure insufflation, and electrical stimulation of the abdominal muscles. Each of these methods requires the active intervention of a caregiver; each also requires coordination with the patient's control of opening and closing the upper airway. In case reports, assisted cough has been associated with dislocation and embolization of vena caval filters and is likely contraindicated in this situation.
| Study | N | Level of Injury | Unassisted Cough Peak Flow (L/min) | Method of Assisted Cough | Percent Improvement in Peak Flow Compared with Unassisted Cough |
|---|---|---|---|---|---|
| Jaeger, Turba, Yarkony et al. (1993) | 24 | C4-C7 | 203±52 | Manual Electrical/no corset | 15% (p < 0.05) 8% (p < 0.05) |
| Lin, Lai, Wu et al. (1998) | 12 | C4-C8 | 271± 15 | Corset Electrical/corset | 2% (p = NS) 18% (p < 0.01) |
| Kirby, Barnerias, and Siebens (1966) | 10 | C5, C6 | 234 | Corset Manual OPP OPP/corset Manual/OPP/corset | 7% 33% 37% 45% 78% |
NS = not significant; L = liters; OPP = oral positive pressure insufflation.
The unassisted cough peak flow ranged from 203 to 271 L/min, a response well below that of unimpaired individuals, but one that would be expected for persons with tetraplegia with lower-cervical injuries. The use of a corset, or abdominal binder, showed negligible improvement in peak flow (2 percent and 7 percent) in two studies (Kirby, Barnerias, and Siebens, 1966; Lin, Lai, Wu et al., 1998). Manual assistance demonstrated larger improvements (15 percent and 33 percent) that were statistically significant in one study (Jaeger, Turba, Yarkony et al., 1993). Electrical stimulation resulted in statistically significant improvement in peak flow during cough in two studies, one in which subjects used a corset (Lin, Lai, Wu et al., 1998), and one in which they did not (Jaeger, Turba, Yarkony et al., 1993). The use of electrical stimulation was limited in one study by two factors: inability of patients to tolerate electrical stimulation (21 percent, 5/24) and inability of patients to obtain sufficiently strong muscle contractions from electrical stimulation (21 percent, 5/24) (Jaeger, Turba, Yarkony et al., 1993). In one study, oral positive pressure insufflation showed large improvements in peak flow with or without a corset; when combined with manual assistance and corset, oral positive pressure improved peak flow to near normal range (Kirby, Barnerias, and Siebens, 1966).
Two studies described the use of a "vigorous" respiratory therapy intervention to prevent or reverse secretion retention and atelectasis. One was a retrospective case series (Sugarman, 1985) and the other a historical cohort comparison (McMichan, Michel, and Westbrook, 1980).
In one series of 128 consecutive SCI admissions, atelectasis based on chest radiograph developed in six patients (Sugarman, 1985). Once atelectasis was identified, the six patients (also included in the series described in Sugarman, Brown, and Musher (1982) were treated with a "vigorous" pulmonary therapy. The vigorous pulmonary therapy included doubling the frequency of routine suctioning, assisted coughing, deep breathing, and incentive spirometry. It also included special attempts to suction the left main bronchus and bronchoscopy as needed. The vigorous pulmonary therapy succeeded in returning the chest radiograph to normal within 24 hours after therapy was initiated in all six patients. In addition, four had improvement in tidal volume and FVC; four had improvement in dyspnea. During subsequent hospital course, three of six had a total of seven recurrent episodes of atelectasis.
McMichan, Michel, and Westbrook (1980) described patients in a prospective series after the institution of a respiratory care protocol to prevent, treat, and assess secretion retention. This series demonstrated lower mortality, atelectasis, need for MV, and tracheostomy than did a retrospective series conducted at the same institution before the protocol had been instituted."Usual care" in the historical series consisted of changing the patient's position every 2 hours, and deep breathing exercises, incentive spirometry, chest percussion, and assisted coughing every 4 hours. The prospective series had a more aggressive regimen, which comprised IPPB, aerosolized bronchodilator treatment, and bronchial lavage in addition to the usual care described above. The difference in mortality was large (0 percent versus 41 percent), although the differences in intermediate outcomes were less impressive. Pulmonary complications of secretion retention and atelectasis favored the aggressive care (four versus 12 cases); need for MV was lower for the aggressive care group (three versus nine cases), and need for tracheostomy was lower for the aggressive care group (two versus six cases). The lack of contemporaneous controls limits one's ability to conclude that all these differences stem from the addition of IPPB, aerosolized bronchodilator treatment, and bronchial lavage. Nevertheless, this study is the only one to link the respiratory care interventions to improvements in health outcomes, as opposed to spirometric parameters.
Management of ventilatory support requires a functional airway. The requirements of an airway change over time. Endotracheal intubation is expedient and is sufficient to establish an airway in acute ventilatory failure or for short-term MV. However, if ventilatory support is needed beyond a few weeks, then a more secure permanent airway, such as a tracheostomy, is often given. Positive pressure ventilation is given through a tracheostomy with an inflated cuff.
The technique for endotracheal intubation is modified when cervical spine injury is known or suspected. Meschino, Devitt, Koch et al. (1992) described the consequences of intubation among 165 patients with cervical spinal fracture with or without cord injury. Intubation was performed on conscious non-sedated patients using a variety of techniques, including oral or nasal intubation with fiberoptic bronchoscopy (46 percent), blind nasotracheal intubation (32 percent), or oral intubation with direct laryngoscopy (22 percent). Neurological deterioration occurred in four of 165 patients (2 percent) who were intubated and in the same proportion of patients managed without intubation (7/289, 2 percent). Investigators reported no cases of gastric aspiration. Most patients were intubated in preparation for surgery and anesthesia (62 percent), and a minority was intubated for respiratory failure (27 percent), airway protection (8 percent), and tracheobronchial toilet (3 percent).
As treatment goals shift from management of acute medical and surgical problems to rehabilitation, the patient's ability to speak is considered in selecting an airway. To enable a patient to speak, the cuff of a tracheostomy tube must be deflated or a cuffless or fenestrated tracheostomy tube must be used. This transition may be performed during ventilatory weaning.
Tracheostomy complications include infection, granulation formation, and mucous accumulation, which can lead to bronchial mucous plugging, atelectasis, pneumonia, and difficulty swallowing. Using cuffed fenestrated tracheostomy tubes exacerbates granulation formation. Other complications of TPPV with cuff inflation include hemorrhage, hemoptysis, pneumothorax, subcutaneous emphysema, tracheomalacia, tracheoesophageal fistula, impingement and erosion of the subclavian artery, and tracheal stenosis.
Patients with tracheostomy PPV sometimes do not tolerate deflation of the tracheostomy cuffs. Leaking around a deflated cuff reduces the efficiency of ventilation. A variable leak may result in either hypoventilation (hypercapnea) or hyperventilation (hypocapnea). Many patients can learn to control this variable insufflation leak while awake; however, when asleep, increased leakage may occur, leading to insufficient ventilation. Excessive leak can be compensated for by increasing delivered volumes to produce the same airway pressures as with the cuff inflated. Cuffs are also often kept inflated in an effort to reduce the risk of aspiration of gastric contents and upper airway secretions.
Many people with neuromuscular disease who are ventilator dependent will chronically hyperventilate (with resulting hypocapnea) unrelated to any variable air leak. Watt and Devine (1995) and Watt and Fraser (1994) tested whether adding dead space of 3 mL/kg could reduce hypocapnia that occurred as a result of the variable leak around a cuffless tracheostomy tube. Investigators described a series of 12 patients with high tetraplegia on chronic tracheostomy PPV who were switched from cuffed to cuffless tube. Addition of dead space increased pCO2 to near-normal levels, reducing hypocapnia during waking and sleeping periods (p < 0.05).
Bach and Alba (1990a) (1990b) reported daytime and overnight oximetry in patients with tetraplegia who were converted to cuffless tracheostomy or who had their cuffs deflated. Investigators used the following procedures: cuffs were deflated for short but increasingly longer periods during the day; volume was adjusted so that ventilatory pressures and blood gases during deflated/cuffless periods were equivalent to those during inflated cuff periods; delivered volumes were adjusted if necessary to compensate for insufflation leak; supplemental oxygen was used if necessary to maintain PO2levels; continuous monitoring of finger pulse SaO2 and end-tidal pCO2 was performed; arterial blood gases (ABGs) were measured; patients were trained to use leak across vocal cords to aid in speech; smaller tracheostomy tubes were inserted if patients needed them for effective speech; once patients could tolerate deflated cuffs during day, they were converted to using such cuffs overnight. Full cuff deflation/removal usually took 1 to 2 weeks. Of 10 patients with SCI, daytime SaO2 was within normal limits. SaO2 was at least 90 percent at all times in eight of 10 patients; in two patients, SaO2 was less than 90 percent for 2 percent and 3 percent of the time, respectively. One of the 10 patients was completely weaned from MV, four became ventilator-free during daytime but not overnight, three could tolerate between 20 minutes and 1 hour off ventilator, and two could tolerate 20 minutes or less. The authors concluded that patients with adequate pulmonary compliance are candidates for conversion to cuffless tracheostomy tube even if they have little or no autonomous respiration.
Bellamy, Pitts, and Stauffer (1973) reported the incidence of pulmonary complications overall, the need for tracheostomy, and pulmonary complications following tracheostomy in their case series of 54 patients with SCI. Most of the tracheostomies were performed within 3 days of injury (28/32 cases, 87 percent). Complications directly related to the tracheostomy included one patient who had minor bleeding and one who was found to have tracheal stenosis following removal of the tracheostomy tube.
A larger series of 46 patients with tracheostomy performed for cervical SCI was reported by Biering-Sørensen and Biering-Sørensen (1992). They found a low incidence of tracheal stenosis (2 percent) over a median 10.4-year followup. Early complications (bleeding from stoma, pneumothorax, and pneumomediastinum) were each reported in three of 46 patients (7 percent).
Patients with cervical SCI are at significant risk for ventilatory failure, and this risk differs by the level and completeness of injury. Ventilatory support is needed for a majority of patients with C5 and higher injuriesand virtually all patients with C3 and higher injuries and in the acute phase. Patients with lower-cervical SCI are less likely to require MV, as are those patients with greater FVC on presentation. The amount of secretions and serious pulmonary infection (pneumonia) are associated with the need for MV. This finding suggests that treatments aimed at improving ventilation, cough, and secretion clearance may reduce the need for MV.
MV for ventilatory failure is usually performed using invasive (endotracheal or nasotracheal) intubation. However, NPPV can be successful for short- and long-term ventilatory assistance when used properly, particularly when patients have spontaneous FVC approaching 1 liter. In patients with C4 LOI, weaning from MV is often a protracted process that is sometimes not successful. However, patients with C4-level SCI appear to have greater success when weaned by progressive ventilatory-free breathing than by synchronized intermittent mandatory ventilation techniques, which are more commonly used in patients with other causes for ventilatory failure. Furthermore, high ventilator volume (> 20 cc/kg) is associated with less atelectasis and faster weaning.
Evidence is available on a variety of therapeutic and clinical assessment strategies among patients with traumatic tetraplegia, including the following:
Active respiratory muscle exercise with incentive spirometry, inspiratory resistance training, and abdominal weight training have all been associated with improvements in spontaneous VC in prospective case series. However, in small randomized controlled trials (RCTs) these techniques have not been shown to improve ventilation, nor have the trials shown any difference between inspiratory resistance training and abdominal weight training.
Deflating cuffed tracheostomies or switching to cuffless tracheostomies is necessary to permit speech, but can cause hypocapnia as a result of increasing tidal volume to compensate for variable upper-airway leak. Adding dead space can increase pCO2 to near-normal levels, reducing hypocapnia during waking and sleeping periods. Speech valves are available to permit better speech.
Electrophrenic respiration has been successfully used for chronic ventilatory support, most often for part-time ventilatory support. Technological advances in recent years appear to have improved the success of the technique, but reliability remains an important problem.
The pneumobelt may be used for part-time ventilatory support or as an adjunct to full-time noninvasive ventilatory support.
Noninvasive ventilation may reduce the risk of pneumonia compared with tracheostomy positive pressure ventilation for patients requiring chronic ventilatory support. This technique may also prevent the need for invasive ventilation in patients with acute ventilatory insufficiency.
Glossopharyngeal breathing training can allow patients ventilator-free breathing for short periods and improve the effectiveness of cough and audibility of their voices.
Cough is improved with manual assisted cough by 15 to 33 percent in two studies. Positive pressure insufflation can improve cough as well. These techniques used together provided near-normal cough peak flows. Although abdominal binding (corset) did not improve spontaneous cough when used alone, when used in conjunction with manual assisted cough, positive pressure insufflation, or both, a trend toward improvement was suggested by one study. It follows that cough can also be improved by mechanical insufflation-exsufflation, as this technique provides 10 liters/second of expiratory flow.
Rotating beds have been associated with lower rates of pulmonary complications compared with less frequent turning with a wedge turning device in patients with cervical SCI in retrospective case series.
Aggressive multimodal respiratory therapy interventions (including frequent turning, suctioning [and bronchial lavage], chest percussion and assisted coughing, inhaled bronchodilator treatments, deep breathing, and incentive spirometry) have been associated with improvements in atelectasis in a small case series. The interventions have also been associated with reduced mortality, atelectasis, need for MV, and tracheostomy in a larger historical cohort comparison.
The reduction in VC associated with a change in position from supine to sitting is both statistically significant and clinically important. Hence, the seated position in which spirometric tests are usually performed is not optimal for patients with cervical SCI, in that FVC will be underestimated in this position.
Periodic chest roentgenography often discloses lesions in patients with tetraplegia, even in the absence of symptoms. Conversely, normal upright chest roentgenograms are not sensitive enough to exclude pulmonary abnormalities, particularly pleural effusions (which can be seen on lateral decubitus views).
In imaging the upper airway, tomography had better agreement with endoscopy for tracheal than glottic stenosis. Computed tomography was more accurate than tomography for diagnosing glottic stenosis, but was similarly accurate for grading the severity of tracheal stenosis.
Studies of bronchodilator effects suggest potential therapeutic benefit from long-term prophylactic therapy with inhaled beta-agonists to reduce symptoms of breathlessness associated with airway reactivity in persons with tetraplegia. However, none of these studies evaluated the long-term efficacy of bronchodilator or other drug treatments on symptoms, pulmonary function, or the incidence of pulmonary complications.
We also conclude the following:
Very little data are available with which to describe the risk of late ventilatory failure or the potential effectiveness of treatments to delay or prevent it.
Despite the expectations of nondisabled persons, the long-term perceived quality of life and well-being are similar in ventilator-dependent and autonomously breathing patients with SCI.
There is a growing body of evidence on the care of persons with traumatic tetraplegia. Although the range of issues this literature addresses is broad, the quality of the literature is relatively low, with few studies using RCT or other designs to reduce bias. Clinical research on patients with cervical SCI has primarily been observational studies, and primarily retrospective case series. Determining the influences of the interventions is problematic for several reasons, including imprecise characterization of treatments and lack of appropriate controls. There is also a need for more precise and consistent characterization of the patients in terms of important prognostic features such as LOI, completeness, and time since injury. Most of the evidence comes from retrospective case series in which the intervention is difficult to characterize. In various studies, the method of clinical care is either not described or described individually for each patient in the series. In some studies that describe well the protocol for care, it is not possible to estimate the effects for individual components of care.
Few of the extant studies have any type of comparison group. Case series can provide rates of outcome events (e. g., complications, successful weaning) that can be compared across series (benchmarks). However, case series provide biased and imprecise estimates of relative effectiveness and are less powerful than study designs that offer internal comparisons (e. g., RCTs, concurrent cohort comparisons, and historical cohort comparisons).
Finally, many of the clinical studies had small sample sizes. A small size limits the generalizability of a case series. For more well-designed studies, the small sample sizes limit the statistical power; for example, the few RCTs identified in this study were negative and lacked the statistical power to show clinically important differences. Future studies should seek to improve both the generalizability and the statistical power by including more patients. Because of the relative rarity of the condition, it will be necessary to aggregate patients through merging standardized data sets from many institutions or developing multisite research networks.
Much of the justification for the current respiratory care of patients with tetraplegia comes from data on or experience with patients with other illnesses, thus guidelines on this topic will need to be based to a large extent on interpretation of these data. Explicit methods are needed for integrating data on related populations with our understanding of the pathophysiology of cervical SCI and other diseases.
Further research is needed to answer definitively questions about how to best care for patients with acute and chronic cervical SCI. The evidence base of clinical research on the management of pulmonary disease in this condition covers only a small number of many important management decisions. However, tetraplegia is associated with important barriers to conducting clinical research. These barriers include the relative rarity of the condition and the relative lack of funding for and expertise in clinical research in SCI care settings.
The U. S. Model Spinal Cord Injury Systems program is a network of (currently) 18 centers that work together to maintain a national database, provide continuing education, and participate in independent and collaborative research relating to SCI. The Model Systems database has contributed greatly to our knowledge regarding the prevalence, natural history, cost, and sequelae of SCI. The Model Systems data have clearly demonstrated improvement in survival of patients with SCI over the last few decades. Furthermore, the database, through measurement of incidence of complications, ventilator use at discharge, and other parameters, has been used to create benchmarks to guide the care of persons with SCI.
Currently the Model Systems database does not collect detailed clinical data of the type needed to examine how differences in clinical practice (e. g., ventilator settings, frequency and type of respiratory therapy) might influence clinical outcomes such as weaning success, time on MV, incidence of atelectasis, or mortality. Agreeing on specific detailed clinical data to collect on day-to-day management practices for persons with SCI, and expanding the Model Systems database to include such data, would make it possible to correlate clinical practices with the health outcomes already obtained in Model Systems data. This would seem a natural extension of the current effort and would facilitate inter-site collaboration in the design and conduct of prospective clinical trials, which would be necessary to definitively answer questions of clinical management.
The Department of Veterans Affairs (VA) network of 23 designated SCI centers handles approximately two-thirds of VA inpatient visits for persons with SCI (Samsa, Landsman, and Hamilton, 1996). The Department has recently developed a national registry of veterans with spinal cord dysfunction to allow more effective planning and administration for SCI care, both in the specialized centers and throughout the network of VA hospitals and clinics (Samsa, Hoenig, Carswell et al., 1998). Clinical data, obtained by linking data from the department's patient treatment file is, like the Model Systems database, insufficiently detailed for effective outcomes research.
Further queries of the Model Systems and VA databases are warranted to describe the occurrence of respiratory illnesses and complications in the course of care following SCI. Few of the currently available reports of Model Systems data have focused primarily on respiratory complications. Despite the lack of detailed data on treatment, the database does provide an opportunity to better describe the epidemiology of respiratory illness and complications. This more-detailed information could be useful for estimating the burden of illness, for modeling, or for cost-effectiveness analysis. These type of data, in turn, will provide motivation for funders to support collaborative clinical research efforts such as those described above.
An active clinical research network would offer the opportunity to implement protocols across multiple institutions, and to test for differences in outcomes associated with different protocols. A variety of management algorithms have been either described in the literature (Clough, Lindenauer, Hayes et al., 1986; Viroslav, Rosenblatt, and Tomazevic, 1996) or put to use within systems (Department of Veterans Affairs, 1994) or single institutions (Branscomb, Stover, DeVivo et al., 1984) (Peterson, personal communication). None of these guidelines was developed using an explicit evidence-based process and none has been rigorously tested in clinical practice. The evidence compiled in this report will be used by the Consortium for Spinal Cord Medicine in their efforts to develop a new guideline using a more explicit process linking recommendations to evidence. The Consortium, professional organizations and similar groups, after examining the current state of research in this area, would be in a good position to outline an agenda for future research by prioritizing questions that would be most useful in guiding clinical care.
Most of the published research on pulmonary disease in SCI focuses on care of acutely injured subjects. As acute SCI is the most expensive condition among all causes for hospitalization (AHRQ, 1999), the acute management phase should be a high priority for research. However, as long-term SCI survival has increased, the prevalence of patients with chronic SCI is growing ever larger. Pulmonary complications of chronic SCI will become of greater clinical importance. Currently, little data is available regarding the incidence of late respiratory failure, and even less is available on the effectiveness of therapies that may be effective to prevent it. In this instance, venues such as the VA Spinal Cord Injury centers and the Model Systems institutions (in which cohorts of patients with chronic cervical SCI are followed) might decide that the systematic collection of data about their patients' clinical care could be valuable.
ABG: arterial blood gas
AbWts: abdominal weights
admiss.: admission
amt: amount
ANOVA: analysis of variance
approx: approximately
ARDS: acute respiratory distress syndrome
Arith.: arithmetic
ASAP: as soon as possible
ASIA: American Spinal Injury Association
ATS: American Thoracic Society
av.: average
BiPAP: biphasic positive airway pressure
Bronch.: bronchodilator
C: cervical
cc: cubic centimeter
CI: confidence interval
cm: centimeter
COPD: chronic obstructive pulmonary disease
CPAP: continuous positive airway pressure
CT: computerized tomography
CV: closing volume
EBEV: extrapolated back expiratory volume
ED: emergency department
EEG: electroencephalogram
EMG: electromyogram
EPAP: expiratory positive airway pressure
EPR: electrophrenic respirator/respiration
ERV: expiratory reserve volume
F: female
FEF: forced expiratory flow
FEF25-75: forced expiratory flow between 25% and 75% of the exhaled volume
FEV: forced expiratory volume
FEV1: forced expiratory volume in 1 second
FIF: forced inspiratory flow
FIV: forced inspiratory volume
FIVC: forced inspiratory vital capacity
FRC: functional residual capacity
FVC: forced vital capacity
Geo.: geometric
GPB: glossopharyngeal breathing
GPmaxSBC: glossopharyngeal maximum single-breath capacity
grp: group
hr: hour
HV: high-volume
Hz: hertz
IAPR: intermittent abdominal pressure respiration
IAPV: intermittent abdominal pressure ventilation
IC: inspiratory capacity
ICD-9: International Classification of Diseases
ICU: intensive care unit
IM: intramuscular
IMT: inspiratory resistive muscle training
IMV: intermittent mandatory ventilation
infect: infection
IPAP: inspiratory positive airway pressure
IPPB: intermittent positive pressure breathing
kg: kilogram
kPa: kilopascal
KTT: kinetic treatment table
L: liter or lumbar
L/s: liter per second
LV: low-volume
M: male
MEF: maximal expiratory flow
mg: milligram
min: minute
MIP: maximum inspiratory mouth pressure
mL: milliliter
mm Hg: millimeters of mercury
MMEF: maximal mid-expiratory flow
mo: month
MV: mechanical ventilation/ventilator
MVV: maximal voluntary ventilation
N: number of pts in population; n = no. of pts in sample; no
N/A: not applicable
Neurol.: neurological
no.: number
N/R: nonresponder
n.s.: not significant
N/S: not specified
NVA: noninvasive ventilatory assistance
OPH: orthostatic position of head
OR: odds ratio
p: probability
PC20: provocative concentration (of methacholine or histamine) that caused a 20% decrease in FEV1
pCO2: partial pressure of carbon dioxide
PEF: peak expiratory flow
PEFR: peak expiratory flow rate
Pemax: increased expiratory mouth pressure
PEP: positive expiratory pressure
PFT: pulmonary function test
PI: principal investigator
PIF: peak inspiratory flow
Pimax: increased inspiratory mouth pressure
PLL: posterior longitudinal ligament
PLV: pressure-limiting ventilator
PO: per os (orally)
pO2: partial pressure of oxygen
Post-tx: post-treatment
PPV: positive pressure ventilation/ventilator
Pre-tx: pre-treatment
PVFB: progressive ventilator-free breathing
pt: patient
PVFB: progressive ventilator-free breathing
r: symbol for correlation coefficient
R: responder
RCT: randomized controlled trial
rehab: rehabilitation
RR: relative risk
RV: residual volume
resp: respiratory
SaO2: arterial oxygen saturation
SCI: spinal cord injury
SD: standard deviation
sec: second
SEM: standard error of the mean
SIP: sustainable inspiratory mouth pressure
SONI: strapless oral/nasal interface
synd: syndrome
T: thoracic
Te: expiratory time
Ti: inspiratory time
TLC: total lung capacity
Ttot: time of total inspiratory and expiratory cycle
TPPV: tracheostomy positive pressure ventilation
tx: treatment
VC: vital capacity
VE or Ve: expiratory volume
VFSS: videofluoroscopic swallowing study
Vt: tidal volume
wk: week
WTD: wedge turning device
X-ray: chest radiograph
Y: yes
yr: year
% incr.: percentage increase
% pred.: percent of predicted normal
4-AP: 4-aminopyridine
µg: microgram
µs: microsecond
Excluded Small Case Series With Fewer Than 10 Subjects
Abelson H, Brewer K. Inspiratory muscle training in the mechanically ventilated patient. Physiother Can 1987;39(5):305-7.
Al-Kaisy AA, Kent AP, Watt JWH. Maintaining ventilation through the Montgomery t-tube. Can J Anaesthesia 1997;44(3):340.
Ali J, Qi W. Pulmonary function and posture in traumatic quadriplegia. J Trauma 1995;39(2):334-7.
Armitage JM, Pyne A, Williams SJ, et al. Respiratory problems of air travel in patients with spinal cord injuries. BMJ 1990;300(6738):1498-9.
Bach JR. Inappropriate weaning and late onset ventilatory failure of individuals with traumatic spinal cord injury. Paraplegia 1993;31(7):430-8.
Bach JR. Mechanical insufflation-exsufflation. Comparison of peak expiratory flows with manually assisted and unassisted coughing techniques. Chest 1993;104(5):1553-62.
Bach JR, McDermott IG. Strapless oral-nasal interface for positive-pressure ventilation. Arch Phys Med Rehab 1990;71(11):910-3.
Baer GA, Talonen PP, Shneerson JM, et al. Phrenic nerve stimulation for central ventilatory failure with bipolar and four-pole electrode systems. Pacing Clin Electrophysiol 1990;13(8):1061-72.
Bake B, Fugl-Meyer AR, Grimby G. Breathing patterns and regional ventilation distribution in tetraplegic patients and in normal subjects. Clin Sci 1972;42(2):117-28.
Banzett RB, Lansing RW, Reid MB, et al. 'Air hunger' arising from increased pCO2 in mechanically ventilated quadriplegics. Respir Physiol 1989;76(1):53-67.
Biering-Sorensen M, Norup PW, Jacobsen E, et al. Treatment of sleep apnoea in spinal cord injured patients. Paraplegia 1995;33(5):271-3.
Chawla JC. Rehabilitation of spinal cord injured patients on long term ventilation. Paraplegia 1993;31(2):88-92.
Danon J, Druz WS, Goldberg NB, et al. Function of the isolated paced diaphragm and the cervical accessory muscles in C1 quadriplegics. Am Rev Respir Dis 1979;119(6):909-19.
Davenport LF. Inhalation therapy in quadriplegic patients. Proc Annu Clin Spinal Cord Inj Conf 1964;13:45-7.
De Boeck H, Vincken W, Cham B, et al. Diaphragmatic pacing in the treatment of chronic respiratory insufficiency of quadriplegic patients. Acta Chir Belg 1989;89(5):276-80.
Dee PM, Suratt PM, Bray ST, et al. Mucous plugging simulating pulmonary embolism in patients with quadriplegia. Chest 1984;85(3):363-6.
Devine A, Watt JW. Anaesthesia and diaphragmatic pacing in patients with tetraplegia. A review of peri-operative management in patients over a 10-year period. Eur J Anaesthesiol 1996;13(6):553-61.
Dicpinigaitis PV, Spungen AM, Bauman WA, et al. Bronchial hyperresponsiveness after cervical spinal cord injury. Chest 1994;105(4):1073-6.
DiMarco AF, Supinski GS, Petro JA, et al. Evaluation of intercostal pacing to provide artificial ventilation in quadriplegics. Am J Respir Crit Care Med 1994;150(4):934-40.
Elefteriades JA, Hogan JF, Handler A, et al. Long-term follow-up of bilateral pacing of the diaphragm in quadriplegia [letter]. N Engl J Med 1992;326(21):1433-4.
Epstein SW, Vanderlinden RG, Man SF, et al. Lung function in diaphragm pacing. Can Med Assoc J 1979;120(11):1360-8.
Esclarin A, Bravo P, Arroyo O, et al. Tracheostomy ventilation versus diaphragmatic pacemaker ventilation in high spinal cord injury. Paraplegia 1994;32(10):687-93.
Estenne M, De Troyer A. Cough in tetraplegic subjects: an active process. Ann Intern Med 1990;112(1):22-8.
Estenne M, Gorini M. Action of the diaphragm during cough in tetraplegic subjects. J Appl Physiol 1992;72(3):1074-80.
Estenne M, Knoop C, Vanvaerenbergh J, et al. The effect of pectoralis muscle training in tetraplegic subjects. Am Rev Respir Dis 1989;139(5):1218-22.
Fairshter RD, Vaziri ND, Gordon S. Frequency and spectrum of pulmonary diseases in patients with chronic renal failure associated with spinal cord injury. Respiration 1983;44(1):58-62.
Forner Valero JV. Postural variations of the capacity in tetraplegics. Paraplegia 1970;8(3):176.
Frankel HL. Tracheal stenosis following tracheostomy. Paraplegia 1970;8(3):172-6.
Frankel HL, Guz A, Noble M. Respiratory sensations in patients with cervical cord transection. Paraplegia 1971;9(3):132-6.
Frankel HL, Mathias CJ, Spalding JM. Mechanisms of reflex cardiac arrest in tetraplegic patients. Lancet 1975;2(7946):1183-5.
Frates RC Jr, Splaingard ML, Smith EO, et al. Outcome of home mechanical ventilation in children. J Pediatr 1985;106(5):850-6.
Fugl-Meyer AR. A model for treatment of impaired ventilatory function in tetraplegic patients. Scand J Rehabil Med 1971;3(4):168-77.
Garner SH, Bloch RF, Sutton JR. Heart rate response to facial immersion and apnea in quadriplegia. Arch Phys Med Rehabil 1985;66(11):763-7.
Garrido-Garcia H, Martin-Escribano P, Palomera-Frade J, et al. Transdiaphragmatic pressure in quadriplegic individuals ventilated by diaphragmatic pacemaker. Thorax 1996;51(4):420-3.
Gilgoff IS, Peng RC, Keens TG. Hypoventilation and apnea in children during mechanically assisted ventilation. Chest 1992;101(6):1500-6.
Glass CA. The impact of home based ventilator dependence on family life. Paraplegia 1993;31(2):93-101.
Glenn WW, Hogan JF, Loke JS, et al. Ventilatory support by pacing of the conditioned diaphragm in quadriplegia. N Engl J Med 1984;310(18):1150-5.
Glenn WW, Holcomb WG, Hogan J, et al. Diaphragm pacing by radiofrequency transmission in the treatment of chronic ventilatory insufficiency. Present status. J Thorac Cardiovasc Surg 1973;66(4):505-20.
Glenn WW, Phelps M, Gersten LM. Diaphragm pacing in the management of central alveolar hypoventilation. pp. 333-45. In: Guilleminault C, Dement WC, Ed. Sleep Apnea Syndromes. New York, Liss, 1978.
Gupta A, McClelland MR, Evans A, et al. Minitracheotomy in the early respiratory management of patients with spinal injuries. Paraplegia 1989;27(4):269-77.
Hammon WE, Martin RJ. Chest physical therapy for acute atelectasis. A report on its effectiveness. Phys Ther 1981;61(2):217-20.
Hjeltnes N. Cardiorespiratory capacity in tetra- and paraplegia shortly after injury. Scand J Rehabil Med 1986;18(2):65-70.
Ivatury R, Siegel JH, Stahl WM, et al. Percutaneous tracheostomy after trauma and critical illness. J Trauma-Inj Infect Crit Care 1992;32(2):133-40.
Jordan SA, Wellborn WR 3d, Kovnick J, et al. Understanding and treating motivation difficulties in ventilator-dependent SCI patients. Paraplegia 1991;29(7):431-42.
Kokkola K, Moller K, Lehtonen T. Pulmonary function in tetraplegic and paraplegic patients. Ann Clin Res 1975;7(2):76-9.
Lerman RM, Weiss MS. Progressive resistive exercise in weaning high quadriplegics from the ventilator. Paraplegia 1987;25(2):130-5.
Levine SP, Koester DJ, Kett RL. Independently activated talking tracheostomy systems for quadriplegic patients. Arch Phys Med Rehab 1987;68(9):571-3.
Linder SH. Functional electrical stimulation to enhance cough in quadriplegia. Chest 1993;103(1):166-9.
Mayr W, Bijak M, Girsch W, et al. Multichannel stimulation of phrenic nerves by epineural electrodes. Clinical experience and future developments. ASAIO J 1993;39(3): M729-35.
McCool FD, Pichurko BM, Slutsky AS, et al. Changes in lung volume and rib cage configuration with abdominal binding in quadriplegia. J Appl Physiol 1986;60(4):1198-202.
McKinley AC, Auchincloss JH Jr, Gilbert R, et al. Pulmonary function, ventilatory control, and respiratory complications in quadriplegic subjects. Am Rev Respir Dis 1969;100(4):526-32.
Mugica J, Dejean D, Smits K, et al. Direct diaphragm stimulation. Pacing Clin Electrophysiol 1987;10(1 Pt 2):252-6.
Oakes DD, Wilmot CB, Halverson D, et al. Neurogenic respiratory failure: a 5-year experience using implantable phrenic nerve stimulators. Ann Thorac Surg 1980;30(2):118-21.
Oku Y, Kurusu M, Hara Y, et al. Ventilatory responses and subjective sensations during arm exercise and hypercapnia in patients with lower-cervical and upper-thoracic spinal cord injuries. Intern Med 1997;36(11):776-80.
Opaskar Hincman H, Ramakrishnan Bhaskar K DeFeudis O'Sullivan D, Brown R, et al. Lipids in airway mucus of acute quadriplegic patients. Experimental Lung Research 1990;16(4):369-85.
Peterson WP, Whiteneck GG, Gerhart KA. Chest tubes, lung entrapment, and failure to wean from the ventilator. Report of three patients with quadriplegia. Chest 1994;105(4):1292-4.
Segal JL, Brunnemann SR, Gordon SK, et al. The absolute bioavailability of oral theophylline in patients with spinal cord injury. Pharmacotherapy 1986;6(1):26-9.
Shwiry B, Joseph S, Sullivan CA, et al. A method of intubation for cervical spine injured patients. AANA J 1983;51(4):403-5.
Silver JR, Abdel-Halim RE. Chest movements and electromyography of the intercostal muscles in tetraplegic patients. Paraplegia 1971;9(3):123-31.
Silver JR, Moulton A. The physiological and pathological sequelae of paralysis of the intercostal and abdominal muscles in tetraplegic patients. Paraplegia 1969;7(2):131-41.
Singas E, Lesser M, Spungen AM, et al. Airway hyperresponsiveness to methacholine in subjects with spinal cord injury. Chest 1996;110(4):911-5.
Thoma H, Gerner H, Holle J, et al. The phrenic pacemaker. Substitution of paralyzed functions in tetraplegia. ASAIO Trans 1987;33(3):472-9.
Tran NV, Vernick J, Cotler JM, et al. Lateral tracheostomy in patients with cervical spinal cord injury. British Journal of Surgery 1995;82(3):412-3.
Vanderlinden RG, Epstein SW, Hyland RH, et al. Management of chronic ventilatory insufficiency with electrical diaphragm pacing. Can J Neurol Sci 1988;15(1):63-7.
Vergith TS. Mechanism of active expiration in tetraplegic subjects [letter]. N Engl J Med 1986;315(19):1233.
Zupan A, Savrin R, Erjavec T, et al. Effects of respiratory muscle training and electrical stimulation of abdominal muscles on respiratory capabilities in tetraplegic patients. Spinal Cord 1997;35(8):540-5.
| MEDLINE: Search 1 |
|
| MEDLINE: Search 2 |
|
| EMBASE Search | |
| 001 | exp spinal cord injury/ |
| 002 | paraplegia/ |
| 003 | quadriplegia/ |
| 004 | spastic paraplegia/ |
| 005 | tetrapleg$.tw. |
| 006 | 1 or 2 or 3 or 4 or 5/ |
| 007 | exp respiratory tract disease/ |
| 008 | ventilator/ |
| 009 | exp assisted ventilation/ |
| 0010 | tracheostomy/ |
| 0011 | postural drainage/ |
| 0012 | 7 or 8 or 9 or 10 or 11/ |
| 0013 | 6 and 12/ |
| 0014 | l/13 lg=en/ |
| 0015 | l/14 hu=y/ |
| 0016 | 15/ |
(2-sided form - see next page)
Treatment of Pulmonary Disease
following Spinal Cord Injury
Screening Decisions: Full-Text Articles
| Reviewer: | _____________________ |
| Record # | _____________________ |
| First Author: | _____________________ |
If decision is to EXCLUDE, check first reason that applies below:
_______1-NoOrig: not original research (or relevant review)
_______2-NoSCI: not traumatic cervical SCI
_______3-NoPulm: not related to pulmonary disease
_______4-Ped: pediatric population (all subjects or mean age <18)
_______5-CR: single case report
_______6-SmCS: small case series (n<20) (if this is the only reason
for exclusion, then please
categorize article by completing
reverse side)
Size of case series N=______
_______7-TE-PE: thromboembolism/pulmonary embolism
Check here _________ if decision is to INCLUDE and complete reverse side.
Check here _________ if article is a RELEVANT REVIEW ARTICLE (i.e., not original research) and complete reverse side
| COMPLICATION (indicate 1 or more) ~ Ventilatory failure ~ Acute ventilatory failure ~ Inability to wean ~ Chronic ventilator dependence ~ Late ventilatory failure ~ Aspiration ~ Atelectasis or lobar collapse ~ Impaired cough, secretion clearance ~ Impaired lung compliance ~ Impaired speech ~ Infect'n (Pneumonia/tracheobronchitis) ~ Pleural effusion ~ Pneumothorax ~ Sleep apnea/nocturnal oxygen desat ~ Tracheal or laryngeal stenosis ~ Other________________________________ SCI TIME COURSE (indicate 1 best) ~ Emergency care min-hrs Stage 0 ~ Medical stab days Stage 1-2 ~ Inpatient rehab weeks-mos Stage 2-3 ~ Community integr mos Stage 4 ~ Long-term f/u years TYPE OF DATA ~ Epidemiology of pulmonary dz in SCI Incidence/prevalence Risk factors Natural history ~ Health services utilization Utilization Costs of care ~ Clinical assessment/measurement ~ Physiological data ~ Efficacy And/Or Harms Of Intervention (indicate intervention class [in italics] below) Airway management Intubation Tracheostomy Trach care Cuff deflation protocol Other ________________ Secretion management Suction and/or bagging, Intermittent NPPV Elevating head/sitting up/postural Assisted cough, manual, electrical Nebulized saline or humidification Passive drainage/Position and turn Roto Rest beds Other ________________ Ventilation management Wean protocol Air-shift maneuvers Glossopharyngeal breathing Deep breathing exercises (inflation hold or incentive spirometer) Diaphragmatic strengthening exercise (wts vs resisted inspiration) Phrenic nerve pacing or FES Manual pectoral-chest stretch ex Noninvasive ventilation (body ventilators, NPPV, BiPAP) Pneumobelt, Abdominal corset Invasive vent (ET or trach) Large volume (>2500cc, pressure control or stacked breaths) Rocking bed (vent assist device) Other ________________ Drug therapy Accolate Antibiotics Bronchodilators Cromolyn, inhaled Guaifenesin Mucolytics Mucomyst Steroids Vaccinations Other ________________ Clinical monitoring and diagnostic tests ABG monitoring Auscultation/Physical exam Chest x-ray (surveillance) Monitor sputum characteristics Monitor temp and RR Oximetry monitoring (day, night) Respiratory function tests Semi-annual evaluation Other ________________ Therapeutic medical/surgical procedures Bronchoscopy Pulmonary medicine consults Other ________________ Patient education and counselling Discourage smoking Other ________________ Diet Milk free diet Other ________________ Other ________________________ |
| Study | Design and Quality | Patient Population | Study Protocol/Interventions | Results/Outcomes |
|---|---|---|---|---|
| Study | Design:Quality: Internal validity External validity | N =Neurol. statusTime since injury:Level of injury:Completeness of injury: (C, I) [for "incomplete," give Frankel, ASIA rating, etc., if provided] Pulmonary status:Age:Sex:Race: |
Health State
Mortality (n = 30)
Bach, Alba, and Saporito, 1993
Bellamy, Pitts, and Stauffer, 1973
Biering-Sorensen and Biering-Sorensen, 1992
Carter, Donovan, Halstead et al., 1987
Claxton, Wong, Chung et al., 1998
Gardner, Theocleous, Watt et al., 1985
Gardner, Watt, and Krishnan, 1986
Glenn, Holcomb, Shaw et al., 1976
Gothe, Maximin, Sajkov et al., 1999
Lamid, Ragalie, and Welter, 1985
McMichan, Michel, and Westbrook, 1980
Miller, Farmer, Stuart et al., 1990
Miller, Thomas, and Wilmot, 1988
Myllynen, Kivioja, Rokkanen et al., 1989
Ryan, Klein, and Bongard, 1993
Sortor, 1992
Splaingard, Frates, Harrison et al., 1983
Viroslav, Rosenblatt, and Tomazevic, 1996
Weese-Mayer, Silvestri, Kenny et al., 1996
Non-fatal Complications (n = 27)
Bach, Alba, and Saporito, 1993
Bach, Rajaraman, Ballanger et al., 1998
Bellamy, Pitts, and Stauffer, 1973
Biering-Sorensen and Biering-Sorensen, 1992
Branscomb, Stover, DeVivo et al., 1984
Claxton, Wong, Chung et al., 1998
Darouiche, Groover, Rowland et al., 1993
Gardner, Watt, and Krishnan, 1986
Glenn, Holcomb, Shaw et al., 1976
Hart, Strauss, and Riker, 1984
Hsu, Dreisbach, Charlifue et al., 1987
Lamid, Ragalie, and Welter, 1985
McMichan, Michel, and Westbrook, 1980
Meschino, Devitt, Koch et al., 1992
Miller, Farmer, Stuart et al., 1990
Myllynen, Kivioja, Rokkanen et al., 1989
Peterson, Barbalata, Brooks et al., 1999
Waites, Canupp, Edwards et al., 1998
Wang, Jaeger, Yarkony et al., 1997
Weese-Mayer, Silvestri, Kenny et al., 1996
Quality of Life (n = 4)
Gardner, Theocleous, Watt et al., 1985
Lamid, Ragalie, and Welter, 1985
Miller, Thomas, and Wilmot, 1988
Health Services
Mechanical Ventilation (n = 14)
Claxton, Wong, Chung et al., 1998
Gardner, Theocleous, Watt et al., 1985
Gardner, Watt, and Krishnan, 1986
McMichan, Michel, and Westbrook, 1980
Miller, Farmer, Stuart et al., 1990
Myllynen, Kivioja, Rokkanen et al., 1989
Tromans, Mecci, Barrett et al., 1998
Viroslav, Rosenblatt, and Tomazevic, 1996
Weaning (n = 13)
Bach, Alba, and Saporito, 1993
Gardner, Watt, and Krishnan, 1986
Lamid, Ragalie, and Welter, 1985
Miller, Farmer, Stuart et al., 1990
Peterson, Barbalata, Brooks et al., 1999
Peterson, Charlifue, Gerhart et al., 1994
Sortor, 1992
Splaingard, Frates, Harrison et al., 1983
Tromans, Mecci, Barrett et al., 1998
Viroslav, Rosenblatt, and Tomazevic, 1996
Tracheostomies (n = 10)
Bach, Alba, and Saporito, 1993
Bellamy, Pitts, and Stauffer, 1973
Biering-Sorensen and Biering-Sorensen, 1992
Lamid, Ragalie, and Welter, 1985
McMichan, Michel, and Westbrook, 1980
Sortor, 1992
Viroslav, Rosenblatt, and Tomazevic, 1996
Hsu, Dresibach, Charlifue et al., 1987
Electrophrenic or Diaph. Pacing (n = 9)
Carter, Donovan, Halstead et al., 1987
Gardner, Watt, and Krishnan, 1986
Glenn, Holcomb, Shaw et al., 1976
Jaeger, Turba, Yarkony et al., 1993
Miller, Farmer, Stuart et al., 1990
Weese-Mayer, Silvestri, Kenny et al., 1996
Hospitalization (n = 9)
Bach, Rajaraman, Ballanger et al., 1998
Claxton, Wong, Chung et al., 1998
Gardner, Theocleous, Watt et al., 1985
Gardner, Watt, and Krishnan, 1986
Ryan, Klein, and Bongard, 1993
Discharge Status (n = 7)
Gardner, Theocleous, Watt et al., 1985
Gardner, Watt, and Krishnan, 1986
Lamid, Ragalie, and Welter, 1985
Sortor, 1992
Splaingard, Frates, Harrison et al., 1983
Spirometry
VC or FVC (n = 35)
Almenoff, Alexander, Spungen et al., 1995
Amodie-Storey, Nash, Roussell et al., 1996
Ashba, Garshick, Tun et al., 1993
Axen, Pineda, Shunfenthal et al., 1985
Bach, Alba, and Saporito, 1993
Chen, Lien, and Wu, 1990
Claxton, Wong, Chung et al., 1998
Derrickson, Ciesla, Simpson et al., 1992
Dicpinigaitis, Spungen, Bauman et al., 1994
Fein, Grimm, Lesser et al., 1998
Forner, Llombart, and Valledor, 1977
Grimm, DeLuca, Lesser et al., 1997
Hart, Strauss, and Riker, 1984
Huldtgren, Fugl-Meyer, Jonasson et al., 1980
Loveridge, Badour, and Dubo, 1989
Maeda, Baydur, Waters et al., 1990
McMichan, Michel, and Westbrook, 1980
Montero, Feldman, and Montero, 1967
Peterson, Barbalata, Brooks et al., 1999
Roth, Lu, Primack et al., 1997
Spungen, Dicpinigaitis, Almenoff et al., 1993
Spungen, Grimm, Strakhan et al., 1999
Tromans, Mecci, Barrett et al., 1998
FEV or FEV1 (n = 15)
Almenoff, Alexander, Spungen et al., 1995
Ashba, Garshick, Tun et al., 1993
Chen, Lien, and Wu, 1990
DeLuca, Grimm, Lesser et al., 1999
Dicpinigaitis, Spungen, Bauman et al., 1994
Fein, Grimm, Lesser et al., 1998
Grimm, DeLuca, Lesser et al., 1997
McMichan, Michel, and Westbrook, 1980
Roth, Lu, Primack et al., 1997
Singas, Grimm, Almenoff et al., 1999
Spungen, Dicpinigaitis, Almenoff et al., 1993
Spungen, Grimm, Strakhan et al., 1999
PEF and/or PEFR (n = 8)
Derrickson, Ciesla, Simpson et al., 1992
Forner, Llombart, and Valledor, 1977
Jaeger, Turba, Yarkony et al., 1993
Spungen, Grimm, Strakhan et al., 1999
Wang, Jaeger, Yarkony et al., 1997
TLC (n = 7)
Huldtgren, Fugl-Meyer, Jonasson et al., 1980
Loveridge, Badour, and Dubo, 1989
McMichan, Michel, and Westbrook, 1980
Roth, Lu, Primack et al., 1997
Other
PC20 (n = 2)
DeLuca, Grimm, Lesser et al., 1999
Dicpinigaitis, Spungen, Bauman et al., 1994
Fein, Grimm, Lesser et al., 1998
Grimm, DeLuca, Lesser et al., 1997
Singas, Grimm, Almenoff et al., 1999
Antibodies (n = 2)
ABG: arterial blood gas
ATS: American Thoracic Society
AHRQ: Agency for Healthcare Research and Quality
BiPAP®: bi-level positive airway pressure
CINAHL: Cumulative Index to Nursing & Allied Health Literature
CPAP: continuous positive airway pressure
CT: computed tomography
CXR: chest roentgenogram
EBEV: extrapolated back expiratory volume
EMG: electromyography
EPR: electrophrenic respiration
ERV: expiratory reserve volume
FEF25-75: forced expiratory flow between 25 and 75 percent of the exhaled volume
FEV: forced expiratory volume
FEV1: forced expiratory volume in 1 second
FIVC: forced inspiratory vital capacity
FIV1: forced inspiratory volume in 1 second
FRC: functional residual capacity
FVC: forced vital capacity
GPB: glossopharyngeal breathing
HBO: hyperbaric oxygen
IC: inspiratory capacity
ICU: intensive care unit
IMV: intermittent mandatory ventilation
IPAP: inspiratory positive airway pressure
IPPB: intermittent positive pressure breathing
KTT: kinetic treatment table
L: liter
LOI: level of injury
MeSH: Medical Subject Heading
MV: mechanical ventilation
MVV: maximal voluntary ventilation
NIDRR: National Institute on Disability and Rehabilitation Research
NIV: non-invasive ventilation
NNPV: non-invasive negative pressure ventilation
NPPV: non-invasive positive pressure ventilation
PC20: provocative concentration that causes a 20 percent decrease in FEV1
PEEP: positive end expiratory pressure
PEF: peak expiratory flow
PEFR: peak expiratory flow rate
PFT: pulmonary function test
Pemax: maximum expiratory pressure
Pimax: maximum inspiratory pressure
PPV: positive pressure ventilation
PVFB: progressive ventilatory-free breathing
RCT: randomized controlled trial
RV: residual volume
SaO2: arterial oxygen saturation
SCI: spinal cord injury
SIMV: synchronized intermittent mandatory ventilation
SIP: sustained inspiratory pressure
TLC: total lung capacity
TPPV: tracheostomy positive pressure ventilation
VC: vital capacity
VFSS: videofluoroscopic swallowing study
WTD: wedge turning device
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