Analyses of human respiratory flow patterns.
Respiratory drives follow various afferent pathways to the respiratory centres; nevertheless, steady-state breathing patterns described in terms of tidal volumes and phase durations are largely independent of the nature of the respiratory stimulus. Flow has now been recorded during steady states from six subjects in rest and hyperpnoea induced by exercise, and hypercapnia in euoxia and in hypoxia (asphyxia). Flow patterns from different stimuli were compared isopnoeically. Quantitative methods allowed the patterns to be described in terms of several variables. The consistent small differences in isopnoeic flow patterns were: In asphyxia, the initial inspiratory acceleration was greater than in hypercapnia, and the peak flow was reached earlier. In exercise the peak flow occurred later in inspiration, and the expiratory flow was maintained high until nearer the end of the phase than with the chemical drives so that the flow pattern was less angular in shape. Stimulus-dependent effects, obvious during transient changes, are greatly attenuated rather than absent in steady states.
Painter
R
R
University Laboratory of Physiology, Oxford, U.K.
Cunningham
D J
DJ
D000328:Adult; D001237:Asphyxia; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D006935:Hypercapnia; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology*