Reflex and mechanical circulatory effects of graded Valsalva maneuvers in normal man.

In 17 normal subjects we studied the changes evoked by five levels of expiratory pressure (EP) ranging from 2.5 to 30 mmHg in a number of circulatory variables during the last 10 s of a 30-s Valsalva maneuver. Variables studied included mean arterial (MAP) and pulse (PP) pressures; right atrial (RAP) and peripheral vein (PVP) pressures; cardiac output (CO); total peripheral resistance (TPR) and heart rate (HR). EP-circulatory response curves were obtained in each subject a) before autonomic block; b) after cardiac effector block (atropine + propranolol); c) after "total" autonomic block (atropine + propranolol; guanethidine + phentolamine). Mechanical effects were determined from results during "total" autonomic block. They included EP-related rises in RAP and PVP each to about 0.7 mmHg/mmHg applied EP, and falls in CO, MAP, and PP to levels of approximately 50%, 70%, and 80% of resting respectively at EP 30 mmHg, but no changes in TPR and HR. Reflex effects included EP-related rises in HR and in TPR and in MAP, to levels of 160%, 160%, and 115% of resting respectively at EP 30 mmHg. The afferent input profile is probably complex, and the role of the different receptor groups may vary at the different levels of EP.