Tourniquet-induced hypertension.

The anaesthetic records of 600 patients undergoing lower limb surgery were reviewed to determine the frequency of intraoperative arterial hypertension (defined as a 30% incision). The overall frequency of hypertension during operation in 500 patients to whom a tourniquet was applied during surgery was 11%. The probability of hypertension was increased if the patient was elderly, had cardiac enlargement shown by x-ray or e.c.g., or had nitrous oxide and narcotic anaesthesia. Pre-existing hypertension, increased serum creatinine concentration, anaemia, or treatment with antihypertensives, diuretics, or steroids were not strongly associated with intraoperative hypertension. A control group of 100 patients undergoing hip surgery without application of a tourniquet exhibited hypertension in 1% of cases.