THE INFLUENCE OF SOME INHALATION ANESTHETIC AGENTS ON THE CONTRACTILE FORCE OF THE HEART

¹ Departments of Pharmacology and Surgery (Anesthesiology), Medical College of South Carolina, Charleston 16, South Carolina

A procedure for the continuous measurement of changes in heart contractile force in intact chronic dog preparations was described. Changes in heart contractile force during the course of ether, chloroform, Vinethene, and cyclopropane anesthesias were recorded.

A depression of heart contractile force was observed during anesthesia with each of the agents studied. Ether, Vinethene, and cyclopropane anesthesias resulted in approximately equal depressions of heart contractile force. Chloroform anesthesia was consistently more depressant to heart contractile force than anesthesia with the other agents tested. Of particular interest was the observation that maximum decrements of heart contractile force during cyclopropane anesthesia were observed at times when arterial pressures were close to or above normal. This is contrasted with the moderate hypotension with ether and the marked hypotension with chloroform during deep anesthesia.

Presumptive evidence for an increased sympatho-adrenal activity during inhalation anesthesia with ether, cyclopropane, chloroform and Vinethene anesthesias was presented.