Haemodynamic effects and outcome analysis of hypotensive extradural anaesthesia in controlled hypertensive patients undergoing total hip arthroplasty.

We have examined the safety of induced hypotension produced by extradural anaesthesia in patients with medically controlled hypertension. The haemodynamic response to induced hypotension was assessed in 38 non-hypertensive and 31 controlled hypertensive patients. All received extradural anaesthesia to T4 or above which decreased mean arterial pressure to 52 mm Hg and 55 mm Hg in normotensive and hypertensive patients, respectively. Cardiac output (thermodilution) was maintained by low dose i.v. infusions of adrenaline (1-5 micrograms min-1). No differences in the haemodynamic response to induced hypotension were observed in hypertensive patients. Data were collected also from 987 consecutive patients (353 hypertensive and 634 non-hypertensive) undergoing total hip replacement. Patients with hypertension were significantly older (68 vs 60 yr; P less than 0.001) and had greater ASA ratings (P less than 0.001). The smallest recorded systolic pressures were reduced more in patients with hypertension (57% vs 52%, respectively; P less than 0.001). The mean duration of maintained intraoperative hypotension (100 and 98 min) and estimated intraoperative blood loss (278 vs 281 ml) were similar in each group. After operation, two patients developed myocardial infarctions. None developed acute renal failure or stroke. There were three deaths; one of a patient who had hypertension. This suggests that induced hypotension with extradural anaesthesia is a safe technique for patients with medically controlled hypertension undergoing total hip arthroplasty.