Metabolic response to total hip arthroplasty under hypobaric subarachnoid or general anaesthesia

Whole blood glucose concentration was estimated in 93 patients undergoing total hip arthroplasty under either subarachnoid or general anaesthesia. In 77, plasma cortisol concentration was also estimated before and after surgery. There were no preoperative differences between the two groups. Blood glucose concentration increased slightly following induction in both groups, but with spinal anaesthesia it decreased again, whereas with general anaesthesia it continued to increase (P less than 0.0001). Plasma cortisol concentration with spinal anaesthesia was 291 (SD 145) nmol litre-1 before, and 279 (253) nmol litre-1 30 min after operation. With general anaesthesia there was a three-fold increase from 301 (159) nmol litre-1 (preoperative) to 987 (474) nmol litre-1 30 min after operation (P less than 0.0001). Low spinal anaesthesia with a predominantly unilateral block appears sufficient to suppress the neuroendocrine response to hip surgery.