Intermittent Positive Pressure Breathing (IPPB) Therapy: Health Technology Assessment Reports, 1991 Number 1

Foreword

The Office of Health Technology Assessment (OHTA) evaluates the risks, benefits, and clinical effectiveness of new or unestablished medical technologies that are being considered for coverage under Medicare. These assessments are performed at the request of the Health Care Financing Administration (HCFA). They are the basis for recommendations to HCFA regarding coverage policy decisions under Medicare.

Questions about Medicare coverage for certain health care technologies are directed to HCFA by such interested parties as insurers, manufacturers, Medicare contractors, and practitioners. Those questions of a medical, scientific, or technical nature are formally referred to OHTA for assessment.

OHTA's assessment process includes a comprehensive review of the medical literature and emphasizes broad and open participation from within and outside the Federal Government. A range of expert advice is obtained by widely publicizing the plans for conducting the assessment through publication of an announcement in the Federal Register and solicitation of input from Federal agencies, medical specialty societies, insurers, and manufacturers. The involvement of these experts helps assure inclusion of the experienced and varying viewpoints needed to round out the data derived from individual scientific studies in the medical literature.

After OHTA receives information from experts and the scientific literature, the results are analyzed and synthesized into an assessment report. Each report represents a detailed analysis of the risks, clinical effectiveness, and uses of new or unestablished medical technologies considered for Medicare coverage. These Health Technology Assessment Reports form the basis for the Public Health Service recommendations to HCFA and are disseminated widely. Individual reports are available to the public once HCFA has made a coverage decision regarding the subject technology.

OHTA is one component of the Agency for Health Care Policy and Research (AHCPR), Public Health Service, Department of Health and Human Services.

• Thomas V. Holohan, M.D.

• Director

• Office of Health Technology Assessment

• J. Jarrette Clinton, M.D.

• Administrator

• Questions regarding this assessment should be directed to:

• Office of Health Technology Assessment

• AHCPR

• Executive Office Center

• 2101 East Jefferson Street, Suite 400

• Rockville, MD 20857; (301) 227-8337

Introduction

Intermittent positive pressure breathing (IPPB) therapy consists of the use of a pressure-limited respirator to deliver a gas, with or without humidity and/or an aerosol solution, at various preset intervals to mechanically aid lung expansion, to deliver drugs, or to assist respirator.(1,2) It is commonly administered through a mouthpiece for short periods of time in a spontaneously breathing and cooperative patient. Alternatively, this technique has been used in patients with reversible acute respiratory failure to forestall or prevent intubation. IPPB has been used in the treatment of acute bronchospasm, croup, chronic obstructive pulmonary disease (COPD), cystic fibrosis, neurologic disorders affecting spontaneous breathing, and as a prophylactic against the pulmonary complications commonly seen after various surgeries.(3-10) During IPPB, the lungs are actively inflated by means of device-regulated positive pressure during inspiration; passive deflation occurs during expiration as a consequence of the elasticity of the lungs and chest wall.(11) The IPPB apparatus includes a precision flow-sensitive valve which opens to a low preset level of inspiratory negative pressure (in patients with spontaneous respiration). This is immediately followed by a gradual increase of airway pressure to a preset level. At the onset of expiration, the valve closes and the airway pressure drops to the ambient atmospheric level, permitting expiration without external resistance. The expired air is released through a second valve, providing a minimal dead space.(12) Compressed or room air is generally used to deliver aerosolized medications, but mixtures of helium and oxygen have also been used in IPPB. Although home use by patients is not uncommon, IPPB is often administered by hospital respiratory therapists three or four times a day for 15-20 minute sessions, usually at pressure and rate levels for adults of 15-20 cm water and 8-10 respirations per minute.(2,13)

Background

Mechanical ventilators provide two basic physiologic functions: maintenance of appropriate alveolar ventilation and of adequate lung volumes and elasticity.(2) Ventilators have been designed and developed to assist, control, or replace a patient's ventilatory effort.(14)

The most common mechanical ventilator is the positive pressure device. The prototype apparatus was initially devised and used during World War II to treat pulmonary edema.(15) Two types are currently in use: the pressure-cycled ventilator, which terminates the inspiratory phase when a predetermined pressure is attained, and the volume-cycled ventilator, which is programmed to deliver a preset volume of gas to the lungs, subject to preset intra-airway pressure as a safety feature. Pressure-cycled ventilators are generally used to deliver IPPB. When a pressure-cycled ventilator is used as an assist device, the negative pressure generated by the patient at inspiration triggers the flow of gas from the ventilator. This type of ventilator can also be operated automatically, i.e., independent of patient inspiratory effort. Volume-cycled ventilators have the advantage of delivering a predetermined volume of gas relatively independent of changes in pulmonary compliance or airway resistance.(14)

Positive pressure ventilators replaced the cumbersome tank-type respirators, and IPPB, originally named inhalation therapy, was introduced into general clinical use in 1947 for providing short-term ventilatory support in the treatment of obstructive lung disease, atelectasis, pneumonitis, and other acute and chronic pulmonary conditions.(16,17) In the ensuing years IPPB and other forms of respiratory therapy (vide infra) that emphasize maximal alveolar inflation have been widely applied as treatment or prophylaxis for a variety of lung disorders despite the general lack of supporting scientific data.(18) By 1974, IPPB was regularly used in 93 of hospitals having 100-199 beds and in 55 of smaller hospitals.(19) However, the efficacy of this technique has been the subject of controversy because the evidence from numerous studies describing its use is conflicting or inconclusive.(8,20-23)

Rationale

Subsequent to the 1947 demonstration by Motley et al(17). that the use of IPPB can increase lung volume and improve blood gas values, proponents of this technology offered the rationale that it would provide the following benefits (especially for patients with COPD).(14,24-26.)

1. Improve distribution of inhaled aerosols or gases to poorly ventilated areas of lung

2. Augment humidity and decrease airway obstruction to facilitate removal of excessive pulmonary secretions

3. Decrease work of breathing

4. Induce cough

5. Increase inspired volume

In addition, it was recognized that postoperative pulmonary complications are the most frequent cause of postoperative morbidity; these complications occur in 20-40 of patients, particularly those subjected to abdominal or thoracic surgery.(21) In 1958, Rudy and Crepeau(27). first proposed the use of IPPB as a method of preventing the common postoperative sequence of progressive alveolar collapse, atelectasis, and pneumonia. Proponents of IPPB have promoted the widespread use of IPPB as a routine postoperative prophylactic technique, especially for patients with COPD, obesity, or cardiovascular diseases and for elderly patients.(28)

Review of Available Information

The effectiveness of IPPB as a means of administering bronchodilators for the treatment of both acute and chronic bronchospastic diseases has been described in a number of studies. Light et al(29). reported excellent bronchodilation with minimal cardiovascular effects in 12 patients with reversible airway obstruction. Branscomb(30). reported an increased effectiveness of bronchodilator plus IPPB vs placebo plus IPPB in the treatment of asthma. His study of 40 patients demonstrated prolonged clinical relief of bronchospasm measured by pulmonary function tests such as airway resistance (AR), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), and forced midexpiratory flow. A substantial placebo response was suggested by the author to be related to the effect of IPPB. Webber et al(6). evaluated 45 patients with severe asthma in a randomized trial of bronchodilator delivered via a simple nebulizer or IPPB and found a slight additional benefit of IPPB in terms of peak expiratory flow rate, when the aerosolized medication was nebulized with IPPB. Anderson et al(31). investigated 10 patients with chronic asthma in a double-blind crossover study of a bronchodilator given by a pressure-packed aerosol or IPPB and found both techniques equally effective in improving measured FEV(1) and FVC.

Other studies have compared IPPB with nebulizers in treating various pulmonary diseases. Pederson and Bungaard(32). studied the effectiveness of a bronchodilator inhaled from different types of apparatus in the treatment of adult asthmatics. In this randomized crossover study, 13 patients used IPPB, two types of pressurized aerosols, or a nebulizer. No significant differences in bronchodilation (measured by flow-volume curves and FEV(1)) were demonstrated by any technique. Fergusson et al(33). conducted a double-blind crossover trial of nebulized bronchodilator with or without IPPB in 20 patients with life-threatening asthma. They reported no difference in the two forms of treatment as measured by the peak expiratory flow rate, arterial oxygenation, and decrease in heart and respiration rates. Klein et al(34). compared the daily home use of IPPB vs oxygen therapy in 44 patients with chronic bronchitis or emphysema plus respiratory insufficiency. Both groups of patients were treated for 22 months and there were no differences in arterial blood gas values or pulmonary function tests (AR, FEV(1), FVC, total lung and functional residual capacities). After 4 years of treatment, the survival rate with oxygen therapy was twice as high as that with IPPB (47 vs 23).

In an evaluation of long-term home use of IPPB, Curtis et al(35). periodically followed a group of 187 patients with chronic bronchitis and emphysema for an average of more than 4 years to determine whether objective benefit was obtained by using IPPB. Seventy-eight patients using IPPB were compared with 109 controls, and no benefit of treatment was observed in terms of FEV(1), blood gas values, body weight, or mortality. In a pairing of 50 IPPB patients with 50 controls, significantly fewer patients using IPPB exhibited improvement in FEV(1).

In 1977 the National Institutes of Health (NIH) sponsored a five-center controlled trial comparing IPPB with compressor nebulizer therapy in 985 ambulatory, stable COPD patients.(8) A bronchodilator aerosol was administered to all patients, who were then randomized and followed for an average of 33 months. Clinical measurements included hospitalizations, mortality, quality of life (measured by standardized questionnaires), and changes in lung function (FEV(1), lung capacities, and diffusing capacity for carbon monoxide). The 1983 report of this trial concluded that IPPB provided no advantage over nebulizer therapy. Although no differences were seen between the two treatments, it was possible, but untested, that neither therapy was effective in this group of patients.(8,18)

Criticism of this trial included the contention that comparing IPPB and compressor nebulizers at the same tidal volume and less than maximum total lung volume does not address the fact that the effect of volume is an important characteristic differentiating these two types of treatment.(18,36)

Sutton et al(37). conducted a general review of chest physiotherapy techniques and concluded that IPPB does not improve the delivery of bronchodilators and is of no benefit (and possibly harmful by causing pneumothorax) in the long-term treatment of chronic bronchitis.

A review of 10 studies of IPPB in the treatment of acute asthma by Eggertsen(38). in 1938 indicated inconsistent and conflicting results, with only three studies reporting the technique to be clinically effective.

Fogel et al(7). studied nebulization of epinephrine alone vs nebulization with IPPB in 14 patients with croup. In this prospective randomized clinical trial, both treatment methods were effective but not distinguishable in croup score reduction; however, treatment was better tolerated with nebulization alone.

In a randomized trial of rehabilitation of 32 patients with COPD, Levine et al(39). compared vs ventilatory muscle endurance training; they found no difference in exercise tolerance after 6 weeks of daily treatments. In this study, IPPB with a bronchodilator was administered to both groups, followed in 2 hours by another course of IPPB or ventilatory muscle training.

Patients with neuromuscular disorders who are unable to take periodic deep breaths would theoretically appear to be candidates for IPPB. However, in a study of IPPB in 10 patients with chronic respiratory muscle weakness associated with generalized neuromuscular disorders, DeTroyer and Deisser(40). reported that these patients did not benefit from IPPB as generally administered (15 minutes four times daily). Measurements included vital capacity, FEV(1), functional residual and total lung capacities, pressure volume curves, and minimal inspiratory pleural pressures.

In a 1984 review of the status of IPPB in treating various pulmonary conditions, Gonzalez and Burke(25). summarized the results of 15 studies (including the NIH trial) comparing IPPB with nebulizer or inhaler therapy in 1,390 patients. Eleven studies failed to demonstrate a significant difference, three studies concluded that IPPB was superior, and one study concluded that IPPB was inferior to other forms or bronchodilator delivery.

There have been a number of reports of the application of IPPB for the prevention or treatment of postoperative pulmonary complications. Gale and Sanders(9). reported no difference in the rate of postoperative atelectasis in 109 heart surgery patients randomized between IPPB and incentive spirometry (IS), a technique in which a patient withdraws a predetermined volume of air from a cylinder, thus tripping a switch that turns on a light. There is a small constant leak in the spirometer so that the patient must continue to inhale to keep the light on for as long as possible. Dohi and Gold(4). randomized 64 postoperative abdominal surgery patients to IPPB or IS and found that although measured spirometric differences were minimal, the rate of development of pneumonia, atelectasis, or bronchitis was significantly higher with IPPB (57 vs 29). In another randomized trial of IPPB vs IS, Van De Water et al(10). evaluated 30 postoperative adrenalectomy patients and found that 6 of 15 patients treated with IPPB and 3 of 15 treated with IS developed pulmonary complications.

In a randomized trial comparing postoperative pulmonary function following chest physiotherapy with or without IPPB in 30 cholecystectomy patients, Ali et al(41). found to additional benefit of added IPPB. Schuppisser et al(42). compared chest physiotherapy and IPPB in 17 patients following abdominal surgery. Using measurements of whole body plethysmography and arterial blood gases, the investigators noted that neither of the modalities was more effective than the other in preventing postoperative pulmonary complications.

Anderson et al, (43). in an early study of IPPB (1963) for the prevention of postoperative pulmonary complications after varied surgeries, administered IPPB to 43 patients. One hundred sixty patients who did not receive IPPB were used as a control group. There was no description of how patients were selected for treatment. Pulmonary complications (fever, cough, rales, or abnormal x-ray) were seen in 2.5 of the IPPB group and 19.5 of the controls.

Jung et al(44). compared IPPB, IS, or resistance breathing as postoperative respiratory care in 126 patients following upper and abdominal surgery. There were no uniform standards of usage of any of the techniques, and no significant difference in the incidence of respiratory complications was noted.

In a case series in which postoperative atelectasis was treated with inspiratory techniques designed to increase functional residual capacity, Paul and Downs(45). studied eight patients after coronary bypass surgery and found that face-mask positive end-expiratory pressure was effective, IS had little or no effect, and IPPB was effective during treatment but had an adverse effect after treatment because residual capacity levels fell below control values. That phenomenon was believed to be secondary to hypoventilation(45). because acute alveolar hypoventilation has been described following IPPB.(46).

Celli et al(1). conducted a randomized trial of IPPB, IS, and deep breathing exercises (DBE) in 172 patients following abdominal surgery. The frequency of pulmonary complications was 48 in the untreated control group, 22 in the IPPB group, 21 in the IS group, and 22 in the DBE group. Criticism of most studies of IPPB involves the failure to describe whether the treatment was optimally delivered and the absence of criteria for what constitutes effective treatment.(47) Data from selected published studies of IPPB are in Tables 1 and 2.

Discussion

Optimal techniques for the delivery of respiratory therapy and patient selection criteria have not been adequately addressed by clinical studies.(22,48) However, the use of IPPB has evolved as a controversial modality in medicine.(5) Despite the immense popularity of IPPB in the 1960s and early 1970s, the increasing number of reports questioning its clinical utility and the conflicting data from controlled trials of its efficacy in the prevention or treatment of pulmonary conditions have resulted in a marked reduction of its use.(49-53) Increasingly, IPPB has represented only a very small percentage of the total volume of respiratory therapy services.(22) The failure of the medical literature to document the efficacy of IPPB has resulted in physicians and respiratory therapists often recommending alternative therapies, including postural change, IS, DBE, cough regimens, chest physiotherapy, and aerosols for therapy and/or prophylaxis.(22,54). Generally agreed upon specifications for the administration of IPPB do not exist. Volumes, flow rates, pressures, duration and frequency of therapy, and associated medication have not been standardized for the treatment of any condition. All the mechanical effects of IPPB are short-lived, lasting only about 1 hour after treatment, and its long-term effects have not been adequately evaluated.(24)

Some case studies have suggested that IPPB might be valuable for the treatment of atelectasis in patients failing DBE or IS, in those with severe bronchospasm, and in patients whose respiratory muscles are fatigued. However, subsets of patients for whom beneficial effects of IPPB can be derived have not been conclusively identified.(5) In addition, it has been stated that it is excessively optimistic to expect IPPB, provided for only 15 minutes three or four times daily, to result in significant clinical benefits.(37)

A beneficial effect of IPPB derives from its ability to deliver aerosolized medications.(6) However, most reported studies have failed to separate the pharmacologic effects of the bronchodilators from the mechanical effects of the IPPB.(5) If IPPB is effective in the treatment of severe COPD or bronchospasm, these positive effects appear to be readily duplicated by more physiologic, simpler, and less costly techniques than IPPB.(1,24,25) The lack of efficacy of IPPB delivered by the commonly applied pressure-cycled devices to prevent or treat postoperative pulmonary complications may be explained by the fact that the machines used to deliver IPPB allow only for a pressure adjustment, without measurement or control of maximum lung volume. Therefore, a reduction in functional residual capacity combined with the typical postoperative decrease in pulmonary compliance results in a smaller volume of gas delivered for the same pressure, which can lead to more shallow ventilation.(54) In the presence of atelectasis, increased inflation pressures could overextend normal alveoli and lead to a ventilation-perfusion mismatch and exacerbation of hypoxemia.

Additional risks of IPPB include infection, excessive ventilation and excessive oxygenation (when using oxygen as the gas source), decreased partial pressure of carbon dioxide during treatment, the induction or exacerbation of pneumothorax, and the exacerbation of hemoptysis.(24,25)

In response to the Federal Register notices of this assessment(55-57). and the solicitation of information and opinions from physicians and institutions involved with IPPB, the Office of Health Technology Assessment has received the following input:

The American Thoracic Society stated that there is no evidence that IPPB is useful or desirable for home use. Possible selected indications for IPPB in hospital may include the management of refractory atelectasis and as a technique in lieu of intubation in patients with acute ventilatory failure.

The American Association for Respiratory Care (AARC) believes that in patients unable to coordinate their breathing pattern to obtain maximal benefit from aerosols delivered by simple devices, the use of IPPB may allow more effective aerosol therapy. IPPB appears to offer no advantage over simple aerosol nebulizer therapy in the treatment of patients with stable, chronic asthma. The AARC recommends IPPB coupled with DBE and chest physiotherapy to help decrease or control unstable carbon dioxide tension in patients with exacerbated COPD and severe ventilatory impairment. In addition, AARC stated that the use of IPPB in the prophylaxis of atelectasis remains controversial. However, IPPB can be beneficial in treating acute lobar atelectasis. The AARC also supports the use of IPPB as coliosis patients who may be at risk of developing respiratory failure.

The National Association of Medical Directors of Respiratory Care position concerning IPPB is that it offers no advantage over alternative modes of routine treatment for most patients with stable asthma, chronic bronchitis, and emphysema, and there is no evidence that IPPB offers any advantage over standard bronchial hygiene therapy. In addition, they stated that IPPB is of value for the following circumstances and should not be regarded as a routine therapeutic modality:

For therapeutic purposes, IPPB (with or without aerosol) may be appropriate for pulmonary atelectasis (segmental or greater) where alternative modes of therapy have been unsuccessful; for patients unable to raise secretions adequately because of the presence of a pathologic process that severely limits their ability to ventilate deeply and cough effectively and who have been unresponsive to, or are judged to be unsuited for, other modes of treatment; and for the temporary treatment of hypoventilating patients where it may be appropriate to use IPPB as an alternative to tracheal intubation and continuous mechanical ventilation. For prophylactic purposes, IPPB may be appropriate to prevent postoperative complications in patients with limited ability to cough or breathe deeply.

The American College of Surgeons believes that there is little evidence to support the concept that IPPB is of value as a preventive measure against the pulmonary complications following any type of major surgery. For the prevention or treatment of postoperative atelectasis, an incentive spirometer and DBE are more effective and less expensive than routine IPPB treatment.

The American College of Chest Physicians believes that IPPB, when used for mechanical ventilation, is clearly indicated as a life-support measure. In addition, for those patients who are unable to breathe slowly and deeply, it is possible that the delivery of a bronchodilator may be more effective with an IPPB device in selected patients. They also believe that there is a role for periodic IPPB administered by skilled therapists in the treatment of pulmonary atelectasis.

The Mayo Clinic stated that there is no evidence to show that IPPB has any advantage in bronchitis and emphysema (COPD). However, IPPB might be of advantage in individuals who have failure of the respiratory muscles due to paralysis or chest wall deformity (eg, kyphoscoliosis), resulting in respiratory "pump" failure. In addition, there is no clear-cut evidence that IPPB used routinely after abdominal surgery prevents pulmonary complications.

The University of Pittsburgh, Division of Pulmonary and Critical Care Medicine, stated that there is no current indication for the use of IPPB as a treatment for acute bronchospasm or COPD, where a spontaneous aerosol is as good as, if not better than, IPPB, and DBE or IS has been shown to be the best way to treat or prevent pulmonary complications following surgery. The only indication for IPPB is to support someone who has stopped breathing until an appropriate, sophisticated, volume-cycled ventilator can be connected.

University of California Los Angeles Medical Center believes that the use of IPPB in the outpatient home setting has no substantive value. IPPB in the acute setting may be useful, in selected patients, in obtaining larger tidal volumes than other techniques.

Boston University Hospitals no longer use IPPB therapy for simple administration of aerosol solutions. However, they believe some benefit may be obtained from administering these solutions by IPPB in patients with severe kyphoscoliosis.

The Midwest Center for Environmental Medicine believes that the usefulness of IPPB is limited to patients with obstructive airway disease with acute carbon dioxide retention and to facilitate aerosolized bronchodilator delivery in patients having tachypnea and confusion. IPPB has been abandoned for the delivery of aerosol therapy per se, and its use for otherwise uncomplicated atelectasis, mucus retention, or postsurgical prophylaxis is to be discouraged.

Consulation with Public Health Service agencies prompted the following responses:

The Food and Drug Administration has classified IPPB devices as Class II medical devices.

The NIH stated that the randomized trial supported by the National Heart, Lund, and Blood Institute demonstrated no significant differences between IPPB and compressor nebulizer therapy in the long-term management of patients with COPD. Studies of IPPB for the treatment of acute episodes of bronchospasm have produced conflicting results, and it appears there is increasing evidence that IPPB is not superior and may be inferior to other prophylactic treatments designed to reduce respiratory complications following abdominal surgery.

Summary

IPPB uses a mechanical respirator to deliver a controlled pressure of a gas to assist in ventilation or expansion of the lungs, thereby providing an increased tidal volume for patients with a variety of pulmonary conditions. IPPB machines are also used for the delivery of aerosol medications.

The early widespread application of IPPB has dramatically diminished in response to published reports of more recent clinical trials that either question its utility or document its futility in the prophylaxis or treatment of the numerous conditions for which it was commonly prescribed.

The effects of IPPB are short-lived, lasting, approximately 1 hour, and the long-term consequences have not been adequated. In no study has IPPB been shown to have unequivocal clinical effectiveness, in terms of morbidity, mortality, or lung function, when used either alone or in combination with other modalities. In general, IPPB is not thought to offer any advantage over simpler therapies in the treatment of COPD or asthma or in preventing or treating postoperative atelectasis. However, IPPB may be useful in the following circumstances: 1) in patients at risk of respiratory failure because of decreased respiratory function secondary to kyphoscoliosis or neuromuscular disorders; 2) in patients with cute severe bronchospasm or exacerbated COPD, who fail to respond to other standard therapy; and 3) in the management of atelectasis that has not improved with simpler therapy (e.g., IS, postural drainage, aerosol therapy).