Abstract

1. In the heart-lung preparation the thiobarbiturates, thiopental and Surital, exhibit only a moderate degree of cardiac toxicity which is no greater than that produced by the corresponding oxygen analogue. On an equal dose basis, Surital is perhaps less toxic, but definitely not more toxic, than thiopental.

2. In the intact dog, anoxia secondary to respiratory failure plays the predominant role in death from thiopental or Surital anesthesia. Abnormalities of cardiac rhythm appear to take origin on the basis of inadequate oxygenation.

3. Peripheral vascular failure, of anoxic or toxic origin, may be a contributory cause of death.