Contribution of airway collapse to supramaximal expiratory flows.

. Contribution of airway collapse to su..ramaximaljlows. J. Appl. Physid. 36(6) : 653-667. 1974.-A flowmeter which enclosed the head and had a 100-Hz frequency response was used to measure rapid expiratory flow events. During these events, peak flow exceeded maximum expiratory flow (V max). Voluntary coughs and rapid expiration had similar time courses with maximum volume ac-celeration of about 300 l/9, while triggered flow transients were of greater amplitude and shorter duration. Because flows greater than V,,, presumably represent a displacement of gas from intra-thoracic airways undergoing dynamic compression, integration of supramaximal flows yielded estimates of the volume displaced from these airways (AVaw). In normal subjects, AVaw ranged from 50 to 150 ml, increasing with pleural triggering pressure and after administration of aerosol bronchodilator. From plots of instantaneous supramaximal flow against its integral, we esti-