UCLA

Background: Intraoperative hypotension has been associated with postoperative complications, but its relationship with postoperative delirium remains debated. Methods: This single-centre retrospective cohort study included adults (≥60 yr) with ASA physical status score of 3 or 4 undergoing major noncardiac surgery, with documented Confusion Assessment Method assessments. Patients with a history of neurosurgery, stroke, dementia, or neurocognitive disorders were excluded. The primary exposure was the cumulative duration of a mean arterial pressure <65 mm Hg (minutes). The primary outcome was postoperative delirium within 7 days, diagnosed via Confusion Assessment Method. Multivariable logistic regression was used to assess the association between intraoperative hypotension and delirium, adjusting for confounders. Results: Among 5171 patients included from 2013-2024, 632 (11.8%) developed delirium. The median (Q1-Q3) duration of surgery and time with mean arterial pressure <65 mm Hg were 281 (199-430) min and 28 (9-61) min, respectively. In models adjusted for patient characteristics and perioperative factors, intraoperative hypotension was associated with increased odds of delirium (odds ratio per 60 min, 1.12; 95% confidence interval, 1.01-1.24; P=0.038). However, after adjusting for year of surgery, the association was attenuated and no longer statistically significant (odds ratio, 1.06; 95% confidence interval, 0.95-1.18; P=0.320). Both intraoperative hypotension exposure and delirium incidence declined significantly over the study period. Conclusions: Although intraoperative hypotension initially appeared to be associated with postoperative delirium, this association was no longer significant when accounting for temporal improvements in perioperative care. Intraoperative hypotension may represent a marker of historical practice patterns rather than an independent causal driver of delirium.