Major abdominal surgery often leads to a marked sympathoadrenal stress response with high concentrations of plasma catecholomines, hypertension, and tachycardia. We compared the effects of sufentanil-propofol with fentanyl-propofol anaesthesia in a controlled, randomised, double-blind study of 18 ASA I-II patients aged 23-64 years undergoing major abdominal surgery. Study parameters were haemodynamics (heart rate [HR], arterial [ABP], central venous, and pulmonary arterial pressures, cardiac index [CI]), arterial catecholamine concentrations, and the median frequency of the electroencephalogram (EEG) power spectrum. METHODS After premedication with flunitrazepam 1-2 mg, promethazine 25-50 mg, and piritramide 7.5-15 mg, a five-lead electrocardiograph and a Lifescan brain activity monitor were attached and indwelling cannulae were inserted into the radial artery and two forearm veins. A thermodilution catheter was placed in the pulmonary artery via the right internal jugular vein. Anaesthesia was induced with either fentanyl 7 micrograms/kg followed by 5 micrograms/kg.h or sufentanil 1 microgram/kg followed by 0.7 microgram/kg.h up to the end of surgery. Additional boli of the opioids were given according to set criteria, resulting in an average consumption of 9.03 micrograms/kg.h fentanyl or 1.22 micrograms/kg.h sufentanil. Propofol 2 mg/kg was given followed by 6 micrograms/kg.h up to the end of surgery. Relaxation was obtained with pancuronium 0.025-0.05 mg/kg before and after induction, after tracheal intubation, before and after skin incision, after opening of the peritoneum, and at the end of surgery. RESULTS No significant differences were observed between the two groups with regard to the study parameters. The duration of surgery and blood loss were similar in both groups, as were patient characteristics. After induction 2 patients in each group developed thoracic rigidity, which was reversible after muscle relaxation. HR, ABP, and CI decreased significantly before skin incision; after surgical stimulation the baseline values were again reached. but not exceeded. No patient developed tachycardia (> 100/min) or hypertension (> 15% higher than baseline pressure) for longer than 10 min during the study period until the end of surgery. The plasma concentrations of epinephrine and norepinephrine decreased significantly during anaesthesia, and under maximum surgical stimulation did not increase higher than the physiological baseline concentrations. The EEG median frequencies decreased after induction, and during the entire anaesthetic period the main activity was in the delta and theta frequency bands. CONCLUSIONS With both regimens, the sympathoadrenal stress response to major abdominal surgery was nearly completely suppressed, resulting in stable haemodynamics during the operations. Sufentanil and fentanyl were equally well suited as analgesic components of total i.v. anaesthesia with propofol.