Breath sound intensity in patients with airway provocation challenge test positive by spirometry but negative for wheezing: a preliminary report.

Wheeze detection has been proposed as an indicator of bronchial responsiveness during airway provocation challenge (APC) test. However, there is evidence that wheeze may be occasionally absent in subjects whose APC is positive by spirometry. We tested the hypothesis that, in this case, inspiratory breath sound intensity (BSI) over the chest is noticeably decreased. Six patients (3 asthmatics and 3 patients with atopic rhinitis) were selected, whose forced expiratory volume in 1 s (FEV1) fell by 20% or more at the end point of the challenge in the absence of concurrent wheezing. Lung sounds were recorded at the right posterior lung base and analysed by computer. Inspiratory BSI at the end point of the challenge was markedly decreased in all patients, a change almost completely reverted by the inhalation of 200 micrograms of salbutamol in all of them but one. These results support the view that BSI monitoring is potentially useful as an indicator of bronchoconstriction during bronchial provocation testing. However, further studies are necessary to confirm this hypothesis.