Epinephrine-induced arrhythmias during halothane anesthesia with the addition of nitrous oxide, nitrogen, or helium in dogs.

The arrhythmogenicity of epinephrine was examined in 34 male mongrel dogs awake and during 1.1 MAC steady state halothane-O2 anesthesia with the addition of 50% N2O, nitrogen, or helium. All anesthetized dogs required more epinephrine than did awake dogs to produce ventricular extrasystoles. Dogs given halothane-N2O were more sensitive to the epinephrine infusion than those given halothane-nitrogen or halothane-helium. The dogs given halothane-N2O also showed a small, but statistically significant difference from dogs given halothane-O2. These results suggest that the addition of N2O to halothane increases the cardiac arrhythmic potential of epinephrine in the dog.