Anaesthesia for 1131 patients undergoing proximal femoral fracture repair: a retrospective, observational study of effects on blood pressure, fluid administration and perioperative anaemia.

Intra-operative hypotension is a frequent occurrence during anaesthesia for hip fracture surgery in older patients with co-morbidities. We analysed retrospective data from the Brighton Hip Fracture Database to determine the intra-operative fall in systolic blood pressure, and the incidence of absolute (lowest systolic blood pressure < 90 mmHg) and relative (> 20% fall in systolic blood pressure from baseline) hypotension during general or spinal anaesthesia among 1131 non-consecutive patients with hip fracture. General anaesthesia for 489 patients (43.2%) produced a greater mean (SD) fall in systolic blood pressure than spinal anaesthesia for 578 patients (51.1%): 34.2% (13.0%) vs 29.7% (10.8%), respectively (p < 0.0001), mean difference 4.5% (95% CI 3.1-5.9%), and was associated with greater mean (SD) intra-operative fluid administration (1555 (801) ml vs 1375 (621) ml, respectively, p < 0.0001). We observed a correlation between the volume of subarachnoid hyperbaric bupivacaine 0.5% and fall in systolic blood pressure (p = 0.004): compared with patients receiving > 1.5 ml (n = 463), fewer patients receiving ≤ 1.5 ml bupivacaine 0.5% (n = 97) experienced episodes of absolute (31.1% vs 11.3%, p < 0.0001) or relative (83.9% vs 26.8%, p < 0.0001) hypotension. Both mean (SD) intravenous fluid administration (1097 ml (439) vs 1431 ml (638), p < 0.0001) and mean peri-operative fall in haemoglobin concentration (2.1 (1.8) g.dl(-1) vs 2.6 (1.7) g.dl(-1), p = 0.009) were lower in the low-dose spinal group. If these data are confirmed by other researchers, intra-operative hypotension (and consequent haemodilution secondary to reactive fluid administration) in this patient group may be reduced by the simple expedient of administering more cautious general anaesthesia, or reduced volumes of subarachnoid local anaesthetic.