| Abstract
| - SUMMARY. The cardiovascular effects of three induction agents, thiopentone, methohexitone and Althesin, and four muscle relaxants, tubocurarine, gallamine, pancuronium and alcuronium, were studied in 110 patients about to undergo either open or closed cardiac surgery. The three induction agents lowered the mean arterial blood pressure to a similar degree, while the heart rate rose with each agent, this rise being most marked with methohexitone. Pancuronium was the only muscle relaxant to produce no significant cardiovascular change. Most patients showed a definite tachycardia after gallamine, but the blood pressure was maintained, while both alcuronium and tubocurarine were accompanied by marked hypotension. Ventricular arrhythmias were infrequent in the study, even during endotracheal intubation. The effects of the induction agents on the arterial blood gases were studied with the patients breathing spontaneously either air or oxygen. The PaO2 fell significantly in the patients breathing air and rose sharply in those breathing oxygen. The PaC02 rose significantly in both groups.
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