THE EFFECT OF BARBITAL ANESTHESIA ON TEMPERATURE REGULATION

Abstract

In a cool environment of 22.0[degree]C. and 50% relative humidity, trained dogs were allowed to rest until shivering and peripheral vaso-constriction had occurred. The animals were then heated by diathermy at a rate equal to the b.m.r. until shivering was inhibited and vasodilatation had occurred. The expts. were performed with and without amytal and pentobarbital anesthesia. Shivering was measured on a mechanical recorder and skin and rectal temps. were measured by thermocouples. Shivering and vasomotor temp. thresholds were suppressed by the anesthetics 1-5[degree], and the small differential temp. range of normal animals was replaced by a differential having a 3 to 5 fold range as a result of anesthesia. Barbital anesthesia in doses required for surgical procedures suppresses the responses to cold but does not completely inhibit them. The order of suppression for temp. regulatory processes in barbital anesthesia is, in order of decreasing severity, 1, body temp.; 2, shivering; 3, vasomotor reflexes.