Intraoperative Hypotension and Postoperative Stroke in Older Patients Who Had Brain Tumor Resections: A Retrospective Cohort Analysis

BACKGROUND: At some level, intraoperative hypotension causes strokes. Elderly neurosurgical patients are presumably at especially high risk. We tested the primary hypothesis that intraoperative hypotension is associated with postoperative stroke in older patients undergoing brain tumor resection. METHODS: Patients >65 years old who had elective craniotomy for tumor resections were included. The primary exposure was the area under the threshold of intraoperative hypotension. The primary outcome was newly diagnosed ischemic stroke within 30 days, confirmed by scheduled brain imaging. RESULTS: Among 724 eligible patients, 98 (13.5%) had strokes within 30 days after surgery, 86% of which were clinically silent. Curves of lowest mean arterial pressure versus stroke incidence suggested a threshold at 75 mm Hg. Area under the threshold of mean arterial pressure below 75 mm Hg was therefore incorporated into multivariable modeling. There was no association of area below 75 mm Hg and stroke (adjusted odds ratio, 1.00; 95% confidence interval, 1.00-1.00). The adjusted odds ratio for area below 75 mm Hg between 1 and 148 mm Hg x minutes was 1.21 (95% confidence interval, 0.23-6.23). When the area below 75 mm Hg exceeded 1117 mm Hg x minutes, the association remained insignificant. In contrast, malignant tumor and history of previous stroke or myocardial ischemia were associated with strokes. CONCLUSIONS: Postoperative strokes were common in older patients who underwent brain tumor resection, with about 14% having ischemic cerebrovascular events within 30 days, of which 86% were clinically silent. Malignant brain tumors and previous ischemic vascular events were associated with postoperative strokes, but area under 75 mm Hg was not.