Splanchnic Circulation During Cyclopropane Anesthesia in Normal Man

Abstract

In 10 normal adult male subjects the administration of cyclopropane caused significant alterations in splanchnic hemodynamics which could not be attributed to hypoxia, hypercarbia, hypothermia, or surgical stimulation. Cyclopropane caused a moderate increase in splanchnic perfusion pressure but a much larger increase in splanchnic vascular resistance, with the result that splanchnic blood flow diminished. The intravenous administration of a small dose (10-12 mg) of hexa-methonium reserved all of these changes. Splanchnic blood volume was diminished in 2 of 5 individuals in whom the measurement was made. The results of this study suggest that cyclopropane causes an increase in the activity of sympathetic vasoconstrictor fibers supplying the liver and intestine. The degree of vasoconstriction produced may be enhanced by the fact that cyclopropane sensitizes vascular smooth muscle to the actions of norepinephrine.