Abstract
Sudden unexplained cardiac arrest in the absence of cardiac pathology is one of the most serious complications that may occur during the course of surgical anesthesia. While the incidence is low, cardiac arrest carries a mortality of 50 per cent. | A review of this subject by Stephenson, 1958 (1), suggests the possibility that such factors as emotional stress, hypoxia, hypercapnia and vagal stimulation may be involved in the cause of this condition. Recently Kramar, McCarthy, Grinnell and Dietz (2) demonstrated the presence of increased blood levels of vasopressin in patients suffering cardiac arrest. Experimental evidence has shown that strong emotional stress, hypercapnia and hypoxia are all capable of eliciting an increased blood level of vasopressin (3). With the realization that vasopressin is a powerful coronary vasoconstrictor, it seemed feasible that this action, combined with hypoxia and increased vagotonia, might be the principal factor involved in the phenomenon of cardiac arrest. Preliminary experiments on rats have shown emotional stress to be an effective method of causing vasopressin release. Therefore, it was suggested that one might use this laboratory approach to study the ability of certain drugs to inhibit pituitary release or antagonize the effects of vasopressin.