LUNG AUSCULTATION IN AIRWAY CHALLENGE TESTING

The appearance of wheezes and changes in inspiratory breath (vesicular ) sound intensity (BSI) were monitored in patients undergoing routine methacholine challenge test (MCT). The results were compared with chan ges in spirometry and to airway hyper-responsiveness (AH). Fifty-four patients were examined. Spirometry was performed before and after the inhalation of cumulative doses of methacholine starting from 25 mu g; a fall in forced expiratory volume in 1 s (FEV(1)) by 20% or more was considered as significant. Lung auscultation was performed by two obse rvers simultaneously using a special stethoscope placed sequentially o ver the posterior right and left upper (interscapular region, 5 cm fro m the fourth thoracic vertebra) and lower lung zones (5 cm below the s capulae). Symptoms were recorded by the patients on a visual analogue scale. In 27 patients, the MCT was positive (MCT+) and in 27 patients it was negative (MCT-). Wheezes were identified at PD20 in 12 MCT+ pat ients while reduced BSI alone was found in 11 patients; in four patien ts, auscultation was normal. In 20 MCT+ patients, either wheezes, dimi nished BSI or both were heard, one to several steps before reaching PD 20. In the MCT- group, wheezes were detected in two patients and dimin ished BSI in four. In MCT+ patients, the mean (+/-SD) perception of sy mptoms at end-challenge was 33% (+/-26), whereas in MCT- patients, it was 13.6% (+/-22). Complete interobserver agreement was found in 95.7% of ausculations performed (Kappa coefficient=0.846). Coupled to spiro metry, lung auscultation may prove useful in airway challenge testing provided the concept is accepted that wheeze appearance and, by extens ion, an acute decrease in BSI, is as legitimate a manifestation of AH as a fall in FEV(1).