Hormonal and haemodynamic responses to upper abdominal surgery during isoflurane and balanced anaesthesia

The purpose of the study was to compare the protective role of different anaesthetic techniques against surgical stress. Sixty patients undergoing elective laparotomy were randomly divided into six groups of ten patients each: Group I was given 0.65 MAC nitrous oxide (66 per cent inspired) and 0.65 MAC isoflurane (0.75 per cent end-expired); Group 11 was given 0.65 MAC nitrous oxide and 1-1.2 MAC isoflurane (1.2-1.4 per cent end-expired); Group III was given the same anaesthetic management as patients in Group I but with the addition offentanyl (2 μg’kg-1) before the skin incision and & of the initial dose every 15 minutes during surgery; Group IV was treated as patients in Group I with an additional infusion ofiidocaine (30 μg-kg-1- min-1); Groups V and VI were given 0.65 MAC of nitrous oxide andfentanyl, 7.5 and 15 μ g.kg-1, respectively, before skin incision with 1/8 of the initial dose every 15 minutes during the operation; diazepam, 5 mg IV each hour of surgery, was given to prevent intraoperative awareness. Cortisol concentration was determined by radioimmunoassay method and catecholamines were measured by high performance liquid gas chromatography in blood samples at different stages perioperatively.