Effects of the Depth of Anesthesia On Peripheral Vascular Dynamics

Abstract

The peripheral hemodynamic changes in waking dogs and in those anesthetized with pentobarbital and morphine-thiopental were evaluated. The parameters evaluated were (1) vaso-motor activity; (2) cardiac output; (3) femoral artery flow; and (4) skin blood flow. The waking, well trained dog showed marked fluctuations in sympathetic activity and skin blood flow with minimal stimulation. It was impossible to attain vasomotor stability in the waking dog. Pentobarbital resulted in immediate vasodilation followed by a decrease in both femoral artery and skin blood flow. Cardiac output decreased to 56% of the control level. The morphine-thiopental combination resulted in a lighter anesthetic level and a more unpredictable pattern of changes in skin and femoral artery flow and cardiac output. These studies emphasized the need for complete information concerning the effects of anesthetic agents. It is sufficient to consider the anesthesia as a constant in the experiment.