New-onset postoperative hypotension in patients recovering from noncardiac surgery

BACKGROUND: It remains unknown whether postoperative mean arterial pressures less than 65 mmHg constitute clinically important hypotension for individual patients, or might be within their normal pressure range. OBJECTIVE: We aimed to evaluate postoperative arterial pressure in patients recovering from noncardiac surgery and determine the proportion of patients in whom a mean arterial pressure less than 65 mmHg constitutes new-onset postoperative hypotension. DESIGN: A prospective observational study. SETTING: German university medical centre between October 2020 and September 2021. PATIENTS: Patients with elevated cardiovascular risk recovering on general wards from noncardiac surgery under general anaesthesia. MAIN OUTCOME MEASURES: Before and after surgery, we automatically measured arterial pressure at 30-min intervals for about 24 h. We considered patients to have new-onset postoperative hypotension when they had a postoperative mean arterial pressure less than 65 mmHg, and their lowest postoperative mean arterial pressure was at least 5 mmHg below their lowest pre-operative mean arterial pressure. RESULTS: We enrolled 307 patients and included 248 in the final analysis. The median IQR duration of surgery was 62 40 to 90 min. Postoperative mean arterial pressure was less than 65 mmHg at least once in 101 patients (41%). In 44 of these 101 patients (44%; 18% of all 248 patients), postoperative mean arterial pressures less than 65 mmHg constituted new-onset postoperative hypotension. In 57 of these 101 patients (56%; 23% of all 248 patients), postoperative mean arterial pressures less than 65 mmHg did not constitute new-onset postoperative hypotension. CONCLUSION: About 40% of our patients recovering from noncardiac surgery on general wards had at least one postoperative mean arterial pressure less than 65 mmHg, and about half of these patients had new-onset postoperative hypotension.