title: Breathing pattern in men during inspiratory elastic loads.
abstract: Breathing pattern was studied in men during inspiratory elastic load applied throughout breathing cycle (CL) or inspiration only (DL). VT decreased similarly under both loads: 40% during 1st loaded breath (1st), 25% after 1 min (min); so did Ti (15% at 1st, 25% at min); Te decreased by 35% under CL, 25% under DL, at both times. Under DL expiratory flow started after a lag of about 0.4 sec, required to raise alveolar pressure above atmospheric. In all subjects the inspiratory muscles activity increased at 1st and in 6 out of 8 the ventilatory response at min was essentially neurogenic. At 1st all subjects recruited expiratory muscles, decreasing FRC by 100--300 ml under DL' in most this phenomenon was negligible at min. Rate of decrease of inspiratory muscle pressure during period of zero flow under DL was proportional to end-inspiratory muscle pressure (Pmuse.i.) and to Pmuse.i./Ti. At beginning of expiration dPmus/dt was greater under DL: under this period difference of Pmus between CL and DL seems mainly due to muscle intrinsic properties.
mesh_terms: D000328:Adult; D006801:Humans; D006935:Hypercapnia; D000860:Hypoxia; D008168:Lung / Q000502:physiology; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013990:Tidal Volume; D013997:Time Factors; D014797:Vital Capacity