Lung sound analysis in the diagnosis of obstructive airway disease

Dyspnea is prevalent and has a broad differential diagnosis. Difficulty in determining the correct etiology can delay proper treatment. Non-invasively obtained acoustic signals may offer benefit in identifying patients with dyspnea due to obstructive airway disease (OAD).

The aim of this pilot study was to determine whether patients with acute dyspnea due to OAD had distinguishing features when studied with a computerized acoustic-based imaging technique.

Respiratory sounds from patients with dyspnea due to OAD (n = 32) and those with dyspnea not due to OAD (n = 39) were studied and compared with normal controls (n = 16).

In patients without OAD and in controls, the ratios of peak inspiratory to peak expiratory vibration energy values (peak I/E vibration ratio) were remarkably similar, 6.3 +/- 5.1 and 5.6 +/- 4, respectively. For the OAD patients, the peak I/E vibration ratio was significantly lower at 1.3 +/- 0.04 (p < 0.01). In the patients without OAD and the controls, the ratios of inspiratory time to expiratory time (I/E time ratio) were again similar, 1.0 +/- 0.1 and 0.99 +/- 0.11, respectively. For the OAD patients, the I/E time ratio was significantly lower at 0.72 +/- 0.19 (p < 0.01).

This modality was useful in identifying patients whose dyspnea was due to OAD. The ability to objectively and non-invasively measure these differences may prove clinically useful in distinguishing the operant physiology in patients presenting with acute dyspnea.