Effects of high-dose fentanyl anaesthesia on the established metabolic and endocrine response to surgery.

The effect of the administration of fentanyl 50 micrograms/kg body weight on the established metabolic response to pelvic surgery was investigated. In comparison with a control group of patients in whom anaesthesia was supplemented with halothane, fentanyl was associated with a significant decrease in only blood lactate concentrations and heart rate. There were no significant differences in blood glucose, plasma non-esterified fatty acids, and plasma cortisol values between the two anaesthetic techniques. It is concluded that the administration of high-dose fentanyl has little effect on the established metabolic response to surgery, compared with the marked changes observed when the same dose is given before the onset of surgical stimulation.