ARRHYTHMOGENIC DOSES OF EPINEPHRINE ARE SIMILAR DURING DESFLURANE OR ISOFLURANE ANESTHESIA IN HUMANS

Background. Inhaled anesthetics can alter the arrhythmogenicity of exogenously administered epinephrine. Although swine anesthetized with desflurane or isoflurane do not differ in their arrhythmic response to exogenous epinephrine, the relative effect of epinephrine in the presence of these anesthetics in humans is untested. Methods. The authors compared the arrhythmogenicity of submucosally administered epinephrine in 36 ASA physical status 1 and 2 patients undergoing transsphenoidal resection of pituitary tumors who were randomly assigned to receive 1.0-1.3 MAC desflurane or isoflurane anesthesia. A surgeon, blinded to the administered anesthetic and the concentration of epinephrine, injected 1:50,000, 1:75,000, or 1:100,000 (20, 13.3, or 10 mug/ml) epinephrine in saline of volumes sufficient for surgical need. The authors defined a positive response as three or more premature ventricular contractions (PVCs) in the 5 min after starting the injection. Results: No patient given either anesthetic developed any PVCs with epinephrine doses less than 7.0 mug/kg. Greater doses of epinephrine (7.0-13.0 mug/kg) produced positive responses at equal frequencies in the two anesthetic groups. Conclusions. The authors concluded that isoflurane and desflurane do not differ in their sensitization of human myocardium to the arrhythmogenic effects of exogenously administered epinephrine.