Enhancing our understanding of computerised adventitious respiratory sounds in different COPD phases and healthy people.

BACKGROUND: Timely diagnosis of acute exacerbations of COPD (AECOPD) is challenging as it depends on patients' reports. AECOPD are characterised by increased airway obstruction, mucus and air trapping, which results in changes in lung acoustics. Thus, adventitious respiratory sounds (ARS) may be useful to detect/monitor AECOPD.

OBJECTIVE: To evaluate computerised ARS changes during AECOPD.

METHODS: 25 non-hospitalised patients with AECOPD (16♂, 70 [62.5-77.0]yrs, FEV1 59 [31.5-73.0]%predicted) and 34 healthy volunteers (17♂, 63.5 [57.7-72.3]yrs, FEV1 103.0 [88.8-125.3]%predicted) were enrolled. ARS at anterior and posterior right and left chest were recorded at hospital presentation (T1), 15 days (T2) and 45 days (T3) after hospital presentation from patients with AECOPD and only once from healthy participants. A subsample of 9 patients (7♂; 66 [60.0-76.0]yrs; FEV1 62 [26.5-74.0]%predicted) was also included to study ARS pre-AECOPD (T0). Number of crackles and wheeze occupation rate (%Wh) were processed using validated algorithms.

RESULTS: During AECOPD, patients presented more inspiratory crackles at T1 than T3 (p = 0.013) and more inspiratory %Wh at T1 than T2 (p = 0.006), at posterior chest. Patients with stable COPD presented more inspiratory crackles (p = 0.012), at posterior chest, and more expiratory %Wh, both at anterior (p < 0.001) and posterior (p = 0.001) chest, than healthy participants. No differences were observed for the remaining ARS parameters or subsamples (p > 0.05).

CONCLUSIONS: Inspiratory crackles seem to persist until 15 days post exacerbation whilst inspiratory %Wh decreased after this period. ARS seem to be sensitive to monitor AECOPD. This information may allow advances in monitoring the recovery time of patients with AECOPD across all clinical and non-clinical settings.