The breathing pattern was studied in man during inspiratory elastic load applied throughout the breathing cycle (CL) or inspiration only (DL). $V_{T}$ decreased similarly under both loads — 40% during the 1st loaded breath (1st), 25% after 1 min (min) — as 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 0.4 sec, required to raise alveolar pressure above atmospheric pressure. In all subjects the inspiratory drive was increased at 1st and in 6 out of 8 the ventilatory response at min was essentially neurogenic. The rate of decrease of inspiratory muscle pressure during the period of zero flow under DL was proportional to end-inspiratory muscle pressure (Pmus{e.i.}) and to Pmus{e.i.}/Ti. At the beginning of expiration dPmus/dt was greater under DL: in this period the difference of Pmus between CL and DL seems mainly due to intrinsic muscle properties.
Referenze Bibliografiche
BLAND S., LAZEROU L., DYCK G. e CHERNIAK R. M. (1967) - The influence of the “chest wall” on respiratory rate and depth, «Respir. Physiol.», 3, 47-54.
CAMPBELL E. J. M., DINNICK D. T. e HOWELL J. B. L. (1961) - The immediate effects of elastic loads on the breathing of man, «J. Physiol. (London)», 156, 260-273.
MARGARIA C. E., ISCOE S., PENGELLY L. D., COUTURE J., DON H. e MILIC-EMILI J. (1973) - Immediate ventilatory response to elastic loads and positive pressure in man, «Respir. Physiol.», 18, 347-369.
PETIT J. M., MILIC-EMILI J. and DELHEZ L. (1960) - Role of the diaphragm in breathing in conscious normal man: an electromyographic study, «J. Appl. Physiol.», 15, 1101-1106.
POPE H., HOLLAWAY R. e CAMPBELL E. J. M. (1968) - The effect of elastic and resistive loading of inspiration on the breathing of conscious man, «Respir. Physiol.», 4, 363-372.
SWANSON G. D., WARD D. S. e BELLVILLE J. W. (1976) - Posthyper-ventilation isocapnic hyperpnea, «J. Appl. Physiol.», 40, 592-596.