Respiration during exercise in conscious laryngectomized humans

Abstract

We compared respiratory patterning at rest and during steady cycle exercise at work rates of 30, 60, and 90 W in 7 male chronically laryngectomized subjects and 13 normal controls. Breathing was measured with a pneumotachograph and end-tidal PCO2 by mass spectrometer. Inspired air was humidified and enriched to 35% O2. Peak flow, volume, and times for the inspiratory and expiratory half cycles, time for expiratory flow, minute ventilation, and mean inspiratory flow were computer averaged over at least 40 breaths at rest and during the last 2 min of 5-min periods at each work rate. During the transition from rest to exercise and with increasing work rate in both groups, there was an increase in respiratory rate and depth with selective and progressive shortening of expiratory time; these responses were not significantly different between the two groups, but there was a suggestion that respiratory "drive" as quantitated by mean inspiratory flow may limit in the laryngectomized subjects at high work rates. Time for expiratory flow increased on transition from rest to exercise and then decreased in both groups as the work rate increased; it was shorter in the laryngectomy than control group at all levels. In the laryngectomized subjects there was significantly more breath-by-breath scatter in some variables at rest, but there was no difference during exercise. It is concluded that chronic removal of the larynx and upper airways in mildly hyperoxic conscious humans has only subtle and, therefore, functionally insignificant effects on breathing during moderate exercise. Evidence is provided that the upper airways can modulate expiratory flow but not expiratory time during exercise.