Effect of Blood Pressure Variability During the Acute Period of Subarachnoid Hemorrhage on Functional Outcomes

BACKGROUND: The association of blood pressure variation with poor outcomes in aneurysmal subarachnoid hemorrhage (aSAH) is unknown. OBJECTIVE: To evaluate the association of systolic blood pressure (SBP) variation and clinical outcomes in aSAH. METHODS: We conducted a retrospective chart review of all aSAH patients treated at an academic institution between 2007 and 2016. Patient demographics, aSAH characteristics, and blood pressure observations for the first 24 h of admission in 4-h intervals were obtained. SBP variability metrics assessed were mean, standard deviation, maximum, minimum, peak, trough, coefficient of variation, and successive variation. The primary outcome was a composite of the modified Rankin scale as good (0-2) or poor (3-6) at last follow-up. Comparisons between outcome groups were performed. Logistic regression models for each significant SBP metric controlling for potential confounders were constructed. RESULTS: The study population was 202 patients. The mean age was 57 yr; 66% were female. The median follow-up time was 18 mo; 57 (29%) patients had a poor outcome. Patients with poor outcomes had higher standard deviation (17.1 vs 14.7 mmHg, P = .01), peak (23.5 vs 20.0 mmHg, P= .02), trough (22.6 vs 19.2 mmHg, P < .01), coefficient of variation (13.9 vs 11.8 mmHg, P <.01), and lower minimum SBP (101.4 vs 108.4, P <.01). The logistic regression showed that every 1-mmHg increase in the minimum SBP increased the odds of good outcomes (odds ratio = 1.03; 95% CI = 1.001-1.064; P = .04). Models including other SBP metrics were not significant. CONCLUSION: Hypotension was found to be independently associated with poor outcomes in patients with aSAH.