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National Asthma Education and Prevention Program, Second Expert Panel on the Management of Asthma. Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Bethesda (MD): National Heart, Lung, and Blood Institute (US); 1997 Jul.

  • This publication is provided for historical reference only and the information may be out of date.

This publication is provided for historical reference only and the information may be out of date.

Cover of Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma

Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma.

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Initial Assessment and Diagnosis of Asthma

Key Points

  • To establish a diagnosis of asthma, the clinician should determine that:
    • Episodic symptoms of airflow obstruction are present.
    • Airflow obstruction is at least partially reversible.
    • Alternative diagnoses are excluded.
  • Recommended mechanisms to establish the diagnosis are:
    • Detailed medical history
    • Physical exam focusing on the upper respiratory tract, chest, and skin
    • Spirometry to demonstrate reversibility
  • Additional studies may be considered to:
    • Evaluate alternative diagnoses
    • Identify precipitating factors
    • Assess severity
    • Investigate potential complications
  • Recommendations are presented for referral for consultation or care to a specialist in asthma care.

Differences from 1991 Expert Panel Report

  • Severity classifications were changed from mild, moderate, and severe to mild intermittent, mild persistent, moderate persistent, and severe persistent.
  • Examples of questions to use for diagnosis and initial assessment of asthma were added.
  • Information on wheezing in infancy and vocal cord dysfunction was expanded in the differential diagnosis section.
  • Criteria for referral were refined with input from specialty and primary care physicians.
  • More specific recommendations for measuring peak expiratory flow (PEF) diurnal variation are made.

The guidelines to help establish a diagnosis of asthma presented in this component are based on the opinion of the Expert Panel.

The clinician trying to establish a diagnosis of asthma should determine that:

  • Episodic symptoms of airflow obstruction are present.
  • Airflow obstruction is at least partially reversible.
  • Alternative diagnoses are excluded.

A careful medical history, physical examination, pulmonary function tests, and additional tests will provide the information needed to ensure a correct diagnosis of asthma (see box 3-1). Each of these methods of assessment is described in this section.

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Box 3-1

Key Indicators for Considering a Diagnosis of Asthma. Consider asthma and performing spirometry if any of these indicators are present. These indicators are not diagnostic by themselves, but the presence of multiple key indicators increases the probability (more...)

Clinical judgment is needed in conducting the assessment for asthma. Patients with asthma are heterogeneous and present signs and symptoms that vary widely from patient to patient as well as within each patient over time.

Medical History

A detailed medical history of the new patient known or thought to have asthma should address the items listed in box 3-2. The medical history can help:

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Box 3-2

Suggested Items for Medical History. A detailed medical history of the new patient who is known or thought to have asthma should address the following items: Symptoms

  • Identify the symptoms likely to be due to asthma. See box 3-3 for sample questions.
  • Support the likelihood of asthma (e.g., patterns of symptoms, family history of asthma or allergies).
  • Assess the severity of asthma (e.g., symptom frequency and severity, exercise tolerance, hospitalizations, current medications). See table 3-1 for a description of the levels of asthma severity.
  • Identify possible precipitating factors (e.g., viral respiratory infections; exposure at home, work, day care, or school to inhalant allergens or irritants such as tobacco smoke). See component 2, Control of Factors Contributing to Asthma Severity, for more details.
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Box 3-3

Sample Questions for the Diagnosis and Initial Assessment of Asthma. A “yes” answer to any question suggests that an asthma diagnosis is likely. In the past 12 months, …

Table 3-1. Classification of Asthma Severity.

Table 3-1

Classification of Asthma Severity.

Physical Examination

The upper respiratory tract, chest, and skin are the focus of the physical examination for asthma. Physical findings that increase the probability of asthma include:

  • Hyperexpansion of the thorax, especially in children; use of accessory muscles; appearance of hunched shoulders; and chest deformity.
  • Sounds of wheezing during normal breathing, or a prolonged phase of forced exhalation (typical of airflow obstruction). Wheezing during forced exhalation is not a reliable indicator of airflow limitation. In mild intermittent asthma, or between exacerbations, wheezing may be absent.
  • Increased nasal secretion, mucosal swelling, and nasal polyps.
  • Atopic dermatitis/eczema or any other manifestation of an allergic skin condition.

Pulmonary Function Testing (Spirometry)

Spirometry measurements (FEV1, FVC, FEV1/FVC) before and after the patient inhales a short-acting bronchodilator should be undertaken for patients in whom the diagnosis of asthma is being considered (Bye et al. 1992;Li and O'Connell 1996). This helps determine whether there is airflow obstruction and whether it is reversible over the short term (see box 3-4 for further information). Spirometry is generally valuable in children over age 4; however, some children cannot conduct the maneuver adequately until after age 7.

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Box 3-4

Importance of Spirometry in Asthma Diagnosis. Objective assessments of pulmonary function are necessary for the diagnosis of asthma because medical history and physical examination are not reliable means of excluding other diagnoses or of characterizing (more...)

Spirometry typically measures the maximal volume of air forcibly exhaled from the point of maximal inhalation (forced vital capacity, FVC) and the volume of air exhaled during the first second of the FVC (forced expiratory volume in 1 second, FEV1). Airflow obstruction is indicated by reduced FEV1 and FEV1/FVC values relative to reference or predicted values. Significant reversibility is indicated by an increase of ≥ 12 percent and 200 mL in FEV1 after inhaling a short-acting bronchodilator (American Thoracic Society 1991) (see figures 3-1 and 3-2 for example of a spirometric curve for this test). A 2- to 3-week trial of oral corticosteroid therapy may be required to demonstrate reversibility. The spirometry measures that establish reversibility may not indicate the patient's best lung function.

Figure 3-1. Sample Spirometry Volume Time and Flow Volume Curves.

Figure 3-1

Sample Spirometry Volume Time and Flow Volume Curves.

Figure 3-2. Report of Spirometry Findings Pre and Post Bronchodilator.

Figure 3-2

Report of Spirometry Findings Pre and Post Bronchodilator.

Abnormalities of lung function are categorized as restrictive and obstructive defects. A reduced ratio of FEV1/FVC (i.e., <65 percent) indicates obstruction to the flow of air from the lungs, whereas a reduced FVC with a normal FEV1/FVC ratio suggests a restrictive pattern. The severity of abnormality of spirometric measurements is evaluated by comparison of the patient's results with reference values based on age, height, sex, and race (American Thoracic Society 1991).

Although asthma is typically associated with an obstructive impairment that is reversible, neither this finding nor any other single test or measure is adequate to diagnose asthma. Many diseases are associated with this pattern of abnormality. The patient's pattern of symptoms (along with other information from the patient's medical history) and exclusion of other possible diagnoses also are needed to establish a diagnosis of asthma. In severe cases, the FVC may also be reduced, due to trapping of air in the lungs.

Office-based physicians who care for asthma patients should have access to spirometry, which is useful in both diagnosis and periodic monitoring. Spirometry should be performed using equipment and techniques that meet standards developed by the American Thoracic Society (1995). Correct technique, calibration methods, and maintenance of equipment are necessary to achieve consistently accurate test results. Maximal patient effort in performing the test is required to avoid important errors in diagnosis and management.

Training courses in the performance of spirometry that are approved by the National Institute for Occupational Safety and Health are available (800-35NIOSH). When office spirometry shows severe abnormalities, or if questions arise regarding test accuracy or interpretation, the Expert Panel recommends further assessment in a specialized pulmonary function laboratory.

Additional Studies

Even though additional studies are not routine, they may be considered. No one test or set of tests is appropriate for every patient. However, the following procedures may be useful when considering alternative diagnoses, identifying precipitating factors, assessing severity, and investigating potential complications:

  • Additional pulmonary function studies (e.g., lung volumes and inspiratory and expiratory flow volume loops) may be indicated, especially if there are questions about coexisting chronic obstructive pulmonary disease, a restrictive defect, or possible central airway obstruction. A diffusing capacity test is helpful in differentiating between asthma and emphysema in patients at risk for both illnesses, such as smokers and older patients.
  • Assessment of diurnal variation in peak expiratory flow over 1 to 2 weeks is recommended when patients have asthma symptoms but normal spirometry (Enright et al. 1994). PEF is generally lowest on first awakening and highest several hours before the midpoint of the waking day (e.g., between noon and 2 p.m.) (Quackenboss et al. 1991). Optimally, PEF should be measured close to those two times, before taking an inhaled short-acting beta2-agonist in the morning and after taking one in the afternoon. A 20 percent difference between morning and afternoon measurements suggests asthma. Measuring PEF on waking and in the evening may be more practical and feasible, but values will tend to underestimate the actual diurnal variation.
  • Bronchoprovocation with methacholine, histamine, or exercise challenge may be useful when asthma is suspected and spirometry is normal or near normal. For safety reasons, bronchoprovocation testing should be carried out by a trained individual in an appropriate facility and is not generally recommended if the FEV1 is <65 percent predicted. A negative bronchoprovocation may be helpful to rule out asthma.
  • Chest x ray may be needed to exclude other diagnoses.
  • Allergy testing (see component 2).
  • Evaluation of the nose for nasal polyps and sinuses for sinus disease.
  • Evaluation for gastroesophageal reflux (Harding and Richter 1992) (see component 2).

The usefulness of measurements of biomarkers of inflammation (e.g., total and differential cell count and mediator assays) in sputum, blood, or urine as aids to the diagnosis of asthma is currently being evaluated in clinical research trials.

Differential Diagnosis of Asthma

Recurrent episodes of cough and wheezing are almost always due to asthma in both children and adults. Underdiagnosis of asthma is a frequent problem, especially in children who wheeze when they have respiratory infections. These children are often labeled as having bronchitis, bronchiolitis, or pneumonia even though the signs and symptoms are most compatible with a diagnosis of asthma. However, the clinician needs to be aware of other causes of airway obstruction leading to wheezing (see box 3-5).

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Box 3-5

Differential Diagnostic Possibilities for Asthma. Allergic rhinitis and sinusitis Foreign body in trachea or bronchus

There are two general patterns of wheezing in infancy: nonallergic and allergic. Nonallergic infants wheeze when they have an acute upper respiratory viral infection, but as their airways grow larger in the preschool years the wheezing disappears. Allergic infants also wheeze with viral infections, but they are more likely to have asthma that will continue throughout childhood. This group may have eczema, allergic rhinitis, or food allergy as other manifestations of allergy. Both groups may benefit from asthma treatment (see Infants and Young Children section, page 94, in component 3-Managing Asthma Long Term).

Vocal cord dysfunction often mimics asthma. Patients with vocal cord dysfunction can present with recurrent severe shortness of breath and wheezing. Vocal cord dysfunction may even cause alveolar hypoventilation, with increases in PCO2 that prompt urgent intubation and mechanical ventilation. Vocal cord dysfunction that mimics asthma is more common in young adults with psychological disorders. It should be suspected when physical examination reveals a monophonic wheeze heard loudest over the glottis. Further evaluation by flow-volume curve revealing inspiratory flow limitation strongly supports the diagnosis of vocal cord dysfunction. Definitive diagnosis—and exclusion of organic causes of vocal cord narrowing—requires direct visualization of the vocal cords. Treatment with speech therapy that teaches techniques for relaxed throat breathing is often effective (Newman et al. 1995; Bucca et al. 1995; Christopher et al. 1983).

General Guidelines for Referral to an Asthma Specialist

Criteria for the referral of an asthma patient have been developed (Spector and Nicklas 1995; Shuttari 1995). Based on the opinion of the Expert Panel, referral for consultation or care to a specialist in asthma care (usually, a fellowship-trained allergist or pulmonologist; occasionally, other physicians with expertise in asthma management developed through additional training and experience) is recommended when:

  • Patient has had a life-threatening asthma exacerbation.
  • Patient is not meeting the goals of asthma therapy (see component 1-Periodic Assessment and Monitoring) after 3 to 6 months of treatment. An earlier referral or consultation is appropriate if the physician concludes that the patient is unresponsive to therapy.
  • Signs and symptoms are atypical or there are problems in differential diagnosis.
  • Other conditions complicate asthma or its diagnosis (e.g., sinusitis, nasal polyps, aspergillosis, severe rhinitis, vocal cord dysfunction, gastroesophageal reflux, chronic obstructive pulmonary disease).
  • Additional diagnostic testing is indicated (e.g., allergy skin testing, rhinoscopy, complete pulmonary function studies, provocative challenge, bronchoscopy).
  • Patient requires additional education and guidance on complications of therapy, problems with adherence, or allergen avoidance.
  • Patient is being considered for immunotherapy.
  • Patient has severe persistent asthma, requiring step 4 care (referral may be considered for patients requiring step 3 care; see component 3-Managing Asthma Long Term).
  • Patient requires continuous oral corticosteroid therapy or high-dose inhaled corticosteroids or has required more than two bursts of oral corticosteroids in 1 year.
  • Patient is under age 3 and requires step 3 or 4 care (see component 3-Managing Asthma Long Term). When patient is under age 3 and requires step 2 care or initiation of daily long-term therapy, referral should be considered.
  • Patient requires confirmation of a history that suggests that an occupational or environmental inhalant or ingested substance is provoking or contributing to asthma. Depending on the complexities of diagnosis, treatment, or the intervention required in the work environment, it may be appropriate in some cases for the specialist to manage the patient over a period of time or comanage with the primary care provider.

In addition, patients with significant psychiatric, psychosocial, or family problems that interfere with their asthma therapy may need referral to an appropriate mental health professional for counseling or treatment. These characteristics have been shown to interfere with a patient's ability to adhere to treatment (Strunk 1987; Strunk et al. 1985)

References

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