Auscultation Findings in Asthma
The cardinal auscultatory finding in asthma is wheeze—typically diffuse, polyphonic, bilateral, and predominantly expiratory—though the absence of wheeze does not exclude asthma, as examination may be entirely normal between acute episodes. 1
Key Auscultatory Characteristics
Wheeze Features
- Polyphonic wheeze (multiple simultaneous pitches) is the hallmark finding, caused by turbulent airflow occurring simultaneously in many airways of different caliber 1
- Predominantly expiratory, though biphasic wheeze (both inspiratory and expiratory) indicates more severe obstruction 2
- Bilateral and diffuse distribution throughout the lung fields 1
- Louder, higher-pitched wheeze spanning the entire expiratory phase correlates with more severe airway obstruction 2
Critical Clinical Pitfall
Wheeze must be distinguished from upper airway noises (stridor, rattles) which parents and clinicians often misidentify as wheeze. 1 The term "wheeze" lacks equivalent translations in many languages and is poorly understood by both clinicians and patients 1. True wheeze is a soft, musical, polyphonic sound heard mainly during expiration 1.
When Examination May Be Normal
- Outside acute exacerbations, there may be no objective signs of asthma whatsoever 1
- Lung function tests and auscultation are frequently normal during stable disease 3
- Patients with chronic asthma may show signs of hyperinflation with or without wheeze 1
Diagnostic Implications
Wheeze Presence
- Documented wheeze on auscultation is considered the most important symptom of asthma and should be recorded in clinical notes 1
- The presence of wheeze makes asthma a strong diagnostic consideration, particularly when recurrent 1, 3
- However, wheeze alone is insufficient for diagnosis—objective testing with spirometry and bronchodilator response is required 1, 3
Wheeze Absence
- Repeatedly normal examination in the presence of symptoms should prompt reconsideration of the asthma diagnosis 1
- Testing is most useful when the patient is symptomatic or when wheezing is present 3
- Consider examining the patient during or immediately after exercise to provoke symptoms 1
Additional Examination Findings
- Hyperinflation may be present in patients with chronic asthma 1
- During acute exacerbations, expect reduced peak expiratory flow or obstructive pattern on spirometry alongside wheeze 1
- The relationship between wheeze characteristics and obstruction severity is too scattered to predict FEV₁ from auscultation alone—objective measurement remains necessary 2, 4
Important Caveats
- Wheezing occurs in many conditions beyond asthma, including COPD, bronchiectasis, foreign body aspiration, tumors, and vocal cord dysfunction 1, 5
- Children with chronic cough as the only symptom (no wheeze) are unlikely to have asthma 1, 3, 6
- Asthma should never be diagnosed based on auscultatory findings alone—at least two abnormal objective tests are required 3, 6