Hypotension during hip fracture surgery and postoperative morbidity: a retrospective analysis

Abstract

Background: Hip fracture is a growing healthcare challenge, with 6-8% 30-day mortality and 20-30% of patients incurring major morbidity. Intraoperative hypotension during hip fracture surgery is associated with increased 30-day mortality regardless of anaesthetic technique. Although a recent trial demonstrated reduced postoperative complications by maintaining intraoperative arterial blood pressure close to baseline, there are no data correlating intraoperative hypotension during hip fracture surgery with postoperative morbidity. Objective: We evaluated the hypothesis that duration and severity of intraoperative hypotension during hip fracture surgery is associated with increased postoperative morbidity. Methods: A retrospective analysis was carried out on n=52 patients undergoing hip fracture surgery between January and June 2017. Electronic measurements of patients' intraoperative systolic arterial pressure (SAP) and mean arterial pressure (MAP) during anaesthesia were reviewed. We calculated the total duration of time where SAP or MAP were below pre-defined thresholds for hypotension (MAP < 75 mmHg, MAP < 55 mmHg, SAP ≤ 80% admission baseline, or SAP ≤ 80% pre-induction baseline). Univariate and bivariate descriptive statistics were generated for all relevant variables. With multivariable regression models containing known predictors, cumulative duration of hypotension was correlated with postoperative comorbidities as quantified by the Clavien-Dindo and Comprehensive Complication Indices. Results: Mean age (± SD) was 78 ± 13 years, 75% were female, 87% were ASA II or III and 60% underwent spinal anaesthesia.Mean Comprehensive Complication Index was 20.4 ± 19.2. Lowest absolute SAP and MAP values were 82 ± 18 mmHg and 55 ± 12 mmHg respectively. Cumulative time of SAP <80% pre-induction value adjusted to gender, age and the Charlson Comorbidity Index was associated with progression to a higher Clavien-Dindo classification (odds ratio: 1.020 per additional minute; 95% CI: 1.008 -1.035; P = 0.003). Conclusions: In this exploratory retrospective analysis, the cumulative time of hypotension during hip fracture surgery correlated with extensive postoperative morbidity when adjusting to other known predictors. Intraoperative cumulative time of hypotension may be a good candidate for larger prediction studies as a predictor of postoperative complications. A randomised controlled trial evaluating active control of intraoperative hypotension on postoperative morbidity in hip fracture