A retrospective, observational, single-centre, cohort database analysis of the haemodynamic effects of low-dose spinal anaesthesia for hip fracture surgery

Background Careful administration of either spinal (intrathecal) or general anaesthesia probably has a greater impact on outcomes after hip fracture surgery than which method is used per se. Intraoperative hypotension is associated with poorer outcomes, but appears less prevalent using lower doses of spinal anaesthesia. Methods In this observational single-centre study, intraoperative noninvasive blood pressure data were analysed from 280 patients undergoing unilateral hip fracture surgery after the administration of hyperbaric spinal bupivacaine 0.5%, 1.3 ml (0.65 mg). Results Mean cohort mean arterial pressure (MAP) remained within 10% of baseline (spinal injection) MAP for 97/98 (99.0%) subsequent aggregated 1-min recording intervals. The prevalences of lowest MAP <70 mm Hg and <55 mm Hg were significantly lower than historical equivalents (Anaesthesia Sprint Audit of Practice 1 and 2) (52.9% and 10.4% vs 71.9% and 23.8%, respectively, both <0.0001). The proportions of 10 551 MAP readings <70 mm Hg and <55 mm Hg were 6.7% and 0.4%, respectively. Forty-five (16.1%) patients had relatively persistent hypotension (MAP ≤70 mm Hg for five or more intraoperative readings), and were statistically more likely to be frail (Nottingham Hip Fracture Score ≥7/10, 37.8% vs 19.6%, P=0.0109) and be taking alpha-/beta-blockers (44.4% vs 24.3%, P=0.0099) than the remaining ‘normotensive’ cohort. Surgical anaesthesia remained effective for up to 190 min, with only one patient requiring supplemental local anaesthesia during skin closure. Conclusions Low doses of hyperbaric spinal 0.5% bupivacaine (1.3 ml, 6.5 mg) are associated with minimal reductions in blood pressure during surgery and provide adequate duration of surgical anaesthesia. Randomised comparisons of lower vs higher/standard doses of spinal anaesthesia are now required to confirm outcome benefits in this vulnerable patient group. Clinical trial registration NCT05799300.