The effect of fentanyl on arginine vasopressin and cortisol secretion during anesthesia

The effects of nitrous oxide-oxygen plus small doses of fentanyl with (N = 7) and without (N = 15) naloxone and the effects of nitrous oxide-oxygen plus halothane (N = 13) on plasma concentration of arginine vasopressin (AVP) and cortisol were studied in normal patients before and during gynecologic laparotomies. Patients given fentanyl alone received incremental doses of 0.002 mg/kg before, during, and after induction of anesthesia. Naloxone, when given, was injected in doses of 0.005 mg/kg before administration of fentanyl. In the fentanyl group, the induction of anesthesia resulted in a significant increase in the plasma AVP levels and a significant decrease in cortisol levels. In contrast, while the halothane group also showed a decrease in plasma cortisol level, there was no change in the AVP levels. There were comparable increases in AVP and cortisol levels in both groups during surgery. Administration of naloxone before fentanyl prevented the increase of plasma AVP levels during anesthesia and surgery and blunted the elevation of plasma cortisol during surgery. Our results suggest that the increase in plasma AVP levels after induction of fentanyl anesthesia may not be induced by the stress of intubation and that small doses of fentanyl may cause AVP release during anesthesia.