Plasma catecholamines during surgical stress: differences between neurolept and enflurane anaesthesia

To evaluate the influence of enflurane and neurolept anaesthesia on the sympatho-adrenal response to surgery, arterial plasma concentrations of adrenaline and noradrenaline were measured at 11 carefully defined events before, during and after cholecystectomy in two groups of five patients. During steady-state anaesthesia prior to operation and after cholangiography, when the operative procedure had been interrupted for 10 min, adrenaline concentrations were similar in the two groups. During periods of stress such as intubation, skin incision and abdominal exploration, adrenaline levels were 4-6 times higher in the neurolept patients compared to the enflurane patients (P less than 0.01), in whom adrenaline levels were very stable. Noradrenaline levels also varied with stress but without difference between the two groups. Systolic blood pressure was approximately 20 mmHg higher during operation in the neurolept group than in the enflurane group (P less than 0.05). It is concluded that enflurane blocks the sympatho-adrenal response to surgical stress more effectively than conventional neurolept anaesthesia.