Intraoperative Mean Arterial Pressure and Postoperative Deep Vein Thrombosis in Patients Undergoing Craniotomy for Presumed High-Grade Glioma Resection: A Secondary Analysis of a Randomized Controlled Trial

Patients with malignant brain tumors exhibit a hypercoagulable state. The risk of postoperative deep venous thrombosis (DVT) is elevated. The association between intraoperative blood pressure and postoperative DVT in this population remains poorly defined. This secondary analysis included adults undergoing elective craniotomy for presumed high-grade glioma from a randomized, double-blind, placebo-controlled trial. Intraoperative mean arterial pressure (MAP) was recorded invasively at 10-second intervals. Hypotension exposure was quantified as cumulative duration, area under the curve, and time-weighted average below absolute thresholds (65, 70, 75 mmHg) and relative thresholds (20%, 30%, 40% decrease from baseline). Baseline imbalances were assessed using absolute standardized differences (ASD), with a pre-specified threshold of 0.32 derived from pre-analysis adaptation to this neurosurgical cohort. Variables exceeding this threshold guided multivariable model construction. A 1:4 propensity score-matched sensitivity analysis was performed with conditional logistic regression. Among 480 patients, 41 (8.5%) developed postoperative lower-extremity DVT. One patient had confirmed pulmonary embolism. Fifteen baseline variables exceeded the pre-specified ASD threshold of 0.32. After adjustment for nine covariates in the expanded multivariable model, midline shift (adjusted OR 4.01, 95% CI 1.59–10.13, P=0.003) and surgery duration ≥5 hours (adjusted OR 2.96, 95% CI 1.40–6.27, P=0.004) remained independent risk factors. Cumulative duration below MAP 75 mmHg remained associated with DVT after comprehensive adjustment (adjusted OR per 10-minute increase 1.029, 95% CI 1.001–1.057, P=0.041). In the 1:4 propensity-matched cohort (n=205), this association persisted with an OR of 1.22 per 30-minute increase (95% CI 1.07–1.39, P=0.003). In patients undergoing craniotomy for presumed high-grade glioma, cumulative intraoperative hypotension below a MAP threshold of 75 mmHg is associated with postoperative DVT after rigorous confounder adjustment and propensity matching. These observational findings support consideration of MAP maintenance ≥75 mmHg in this high-risk population. Prospective validation is required.