Effects of Pentobarbital Anesthesia, High Spinal Cord Section and Large Doses of Ganglioplegic Agents on Hemodynamic Functions Measured By Dye Dilution

Abstract

Pentobarbital anesthesia increases arterial pressure in normal dogs, apparently by increasing peripheral resistance; mean circulation time, cardiac output and central and "needle-to-needle" (N-N) volumes are unchanged. Two or 3 days after section of the spinal cord at C6, conscious dogs show prolonged mean circulation time, decreased cardiac output and central, N-N, total blood and plasma volumes, and arterial pressure while peripheral resistance is unchanged or increased. Appropriately cautious intravenous infusion of large doses of a mixture of tetraethylam-monium and hexamethonium chlorides causes, in supine anesthetized normal dogs, prolongation of mean circulation time, small decrease in cardiac output, peripheral resistance and arterial pressure, together with significant increases in central and N-N volumes and small increases in total blood and plasma volumes. In conscious dogs previously subjected to spinal cord section, similar giving of the ganglioplegic mixture decreases mean circulation time and had little effect on cardiac output, arterial pressure or peripheral resistance; in contrast to its effect in normal dogs, the infusion decreases central and N-N volumes; total blood and plasma volumes are slightly increased.