The incidence of postoperative hypotension among non-cardiac surgical specialties: A single-centre retrospective cohort study

Postoperative hypotension is associated with increased risk of postoperative complications and mortality. There are limited studies quantifying the incidence of this potentially life-threatening condition among different surgical cohorts. We aimed to describe and compare the incidence of postoperative hypotension in the first 48 h after leaving the post-anaesthesia care unit (PACU) across different surgical specialties after non-cardiac surgery. We conducted a single-centre retrospective study at the Royal Melbourne Hospital. The primary outcome was postoperative hypotension (systolic blood pressure (SBP) <90 mmHg) within 48 h after surgery and discharge from PACU, noted on routine blood pressure monitoring or a requirement for postoperative vasopressor or inotropic support. We estimated odds ratios (OR) using mixed-effects logistic regression models to account for multiple surgical procedures within the same patient. We identified 11,634 surgeries from 17 specialties, of which 47.3% were emergency operations. The median age was 53 years (interquartile range 35–68), with 42.2% being female and 42.5% of patients on regular antihypertensive medication. The overall incidence of ward hypotension was 4.4%. Trauma had the highest rate of postoperative hypotension (27.3%), followed by thoracic surgery (11.6%). Surgical specialties that had a higher risk of hypotension included trauma surgery (OR 13.0, 95% confidence interval (CI) 3.7–46.0) and thoracic surgery (OR 3.6, 95% CI 2.3–5.5). Specialties with a lower risk of hypotension included breast and endocrine surgery (OR 0.4, 95% CI 0.2–0.7) and plastic surgery (OR 0.4, 95% CI 0.3–0.6). Postoperative hypotension is relatively common with substantial variation in incidence between surgical specialties. These findings highlight the need for heightened vigilance for hypotension in certain patients.