Sudden death in the presence of overt β-adrenergic receptor activation in guinea pigs immediately following isoflurane anesthesia


Brian R Overholser, Purdue University School of Pharmacy and Pharmaceutical Sciences, W7555 Myers Building, WHS, 1001 West 10th Street, Indianapolis, IN 46202, USA. E-mail:


Observations  A case series of sudden death is reported in five consecutive guinea pigs following anesthesia with inhalational isoflurane during β-adrenergic receptor stimulation with isoproterenol. Sustained-release isoproterenol pellets or mini-osmotic pumps were implanted subcutaneously in male Dunkin–Hartley guinea pigs as part of a research study to assess the interplay of adrenergic receptor activation and the development of atrial arrhythmias. The continuous exposure to isoproterenol resulted in a similar presentation and eventual sudden death in all guinea pigs exposed to inhalational isoflurane between 15 to 40 minutes after discontinuation of anesthesia. Death occurred in guinea pigs in this case series despite the fact that doses of isoproterenol used were more than 10-fold lower than previously reported in guinea pigs in the absence of isoflurane anesthesia. The cause of death was suspected to be due to an interaction of isoproterenol with isoflurane anesthesia, as placebo implantation or anesthesia alone did not result in cardiac arrest. Of four subsequent guinea pigs anesthetized with the combination of xylazine and ketamine (X/K), three survived isoproterenol implantation for the full 21-day study period while one died perioperatively.

Conclusions  There was an increased rate of post-anesthetic mortality associated with isoproterenol pellet implantation in guinea pigs anesthetized with isoflurane compared to X/K. This may be due to the detrimental effects of the combination of isoflurane during overt β-adrenergic receptor activation or cardioprotective effects of X/K anesthesia during β-adrenergic receptor hyperactivity.