Postanesthetic shivering in primates: inhibition by peripheral heating and by taurine

There has been little research on the cause(s) of postanesthetic shivering (PAS) and on specific interventions. Therefore, the authors investigated PAS in eight unoperated squirrel monkeys anesthetized with halothane-nitrous oxide mixture. Shivering developed in all monkeys in which body temperature was allowed to decrease (mean +/- SEM, 2.8 +/- 0.6 degrees C) during anesthesia. Shivering occurred in 25% of animals in which body temperature was actively maintained at preanesthetic levels during anesthesia. No shivering occurred in animals warmed both during and after anesthesia. Application of radiant heat to the skin stopped PAS immediately, even though deep body temperature remained low; shivering resumed within seconds after this heating was discontinued. Intracerebroventricular (0.1-2 mg) and intravenous (100 mg/kg) administration of the putative inhibitory neurotransmitter taurine also stopped the shivering in preliminary experiments, but central injection of alpha-melanocyte stimulating hormone (100-300 micrograms), an endogenous antipyretic, did not. The results implicate reduced body temperature and activation of central heat production pathways as major factors in PAS and suggest that halothane-nitrous oxide anesthesia per se, elevation of the thermal set-point, and surgical procedures are not essential to the shivering phenomenon. The results suggest for future study two methods to control PAS: application of radiant heat or administration of taurine.