» Articles » PMID: 3612571

Immediate Ventilatory Response to Sudden Changes in Venous Return in Humans

Overview
Journal J Physiol
Specialty Physiology
Date 1986 Nov 1
PMID 3612571
Authors
Affiliations
Soon will be listed here.
Abstract

We changed venous return transiently by postural manoeuvres, and by lower body positive pressure, to see what happened simultaneously to ventilation. Cardiac output was measured by a Doppler technique. In seven subjects, after inflation of a pressure suit to 80 and 40 mmHg at 30 deg head-up tilt, both cardiac output and ventilation increased. Ventilation increased rapidly to a peak in the first 5 s, cardiac output more slowly to a steady state in about 20 s, at 80 mmHg inflation. After inflation to 80 mmHg in six subjects at 12.5 deg head-up and 30 deg head-down tilt, cardiac output did not change in the first, and fell in the second case. There were no significant changes in ventilation. On release of pressure there were transient increases in both cardiac output and ventilation, with ventilation lagging behind cardiac output, in contrast to (2) above. In five subjects, elevation of the legs at 30 deg head-up tilt caused a rise in both cardiac output and ventilation, but in two subjects neither occurred. In all seven subjects there was a transient increase in cardiac output and ventilation when the legs were lowered. Ventilation and cardiac output changes were approximately in phase. We were therefore unable to dissociate entirely increasing cardiac output from increasing ventilation. The relation between them was certainly not a simple proportional one.

References
1.
Mehta N, Iyawe V, Cummin A, Bayley S, Saunders K, Bennett E . Validation of a Doppler technique for beat-to-beat measurement of cardiac output. Clin Sci (Lond). 1985; 69(4):377-82. DOI: 10.1042/cs0690377. View

2.
Tuckman J, Shillingford J . Effect of different degrees of tilt on cardiac output, heart rate, and blood pressure in normal man. Br Heart J. 1966; 28(1):32-9. PMC: 459038. DOI: 10.1136/hrt.28.1.32. View

3.
Goodwin G, McCloskey D, Mitchell J . Cardiovascular and respiratory responses to changes in central command durin isometric exercise at constant muscle tension. J Physiol. 1971; 219(2):40P-41P. View

4.
Ward S, Whipp B, Koyal S, Wasserman K . Influence of body CO2 stores on ventilatory dynamics during exercise. J Appl Physiol Respir Environ Exerc Physiol. 1983; 55(3):742-9. DOI: 10.1152/jappl.1983.55.3.742. View

5.
Vanbenthuysen K, Swanson G, WEIL J . Temporal delay of venous blood correlates with onset of exercise hyperpnea. J Appl Physiol Respir Environ Exerc Physiol. 1984; 57(3):874-80. DOI: 10.1152/jappl.1984.57.3.874. View