Added Respiratory Sounds in COPD Patients
The primary added respiratory sounds in COPD patients are wheezes (rhonchi) and crackles, with wheezes being predominantly expiratory and crackles typically inspiratory and coarse in character. 1
Wheezes (Rhonchi)
Wheezes are the most characteristic added sound in COPD and serve as useful indicators of airflow limitation:
- Wheezing during tidal breathing is a useful clinical indicator of airflow limitation, though it does not correlate with severity 1
- Rhonchi are especially prominent on forced expiration and represent low-pitched, continuous rumbling sounds with frequencies around 200 Hz or less 1, 2
- Expiratory wheeze rate is higher than inspiratory wheeze rate in COPD patients 3
- Wheezes often clear with coughing and may vary between days and throughout a single day 2, 4
Important Caveat
The absence of wheezing does not exclude COPD - physical signs alone are poor guides to severity, and their absence does not rule out the diagnosis 1, 4
Crackles
Crackles in COPD have distinctive characteristics that differ from other respiratory conditions:
- Crackles are predominantly inspiratory (2.9-5 inspiratory vs. 0.73-2 expiratory) 3
- Crackles in COPD are characteristically coarse, with long initial deflection width (1.88-2.1 ms) and two-cycle duration (7.7-11.6 ms) 3
- The period of crackling is shorter in COPD compared to conditions like fibrosing alveolitis or bronchiectasis 5
- Inspiratory crackling terminates significantly earlier in COPD than in other conditions like heart failure or bronchiectasis 5
Additional Respiratory Findings
Beyond added sounds, other respiratory examination findings include:
- Prolonged forced expiratory time (>5 seconds) is a useful indicator of airflow limitation 1, 4
- Diminished breath sounds may be present but are poor guides to severity 1, 4
- Pursed-lip breathing usually implies severe airflow obstruction 1, 4
Clinical Context During Exacerbations
During acute exacerbations, respiratory sounds may change:
- Increased sputum production and wheeze accompany the key symptom of increased dyspnea 1
- Computerized analysis has identified two different patterns of respiratory sound presentation and evolution during COPD exacerbations 6
Critical Diagnostic Limitation
Physical examination findings, including the presence of rhonchi, wheezes, or crackles, are insufficient for diagnosis and must be confirmed with objective spirometry testing showing post-bronchodilator FEV1/FVC ratio <0.70 1, 2, 4
The sensitivity of physical examination for detecting or excluding moderately severe COPD is poor, and reproducibility of physical signs is variable 1, 4