Positive Fluid Balance is Associated with Poor Outcomes in Subarachnoid Hemorrhage

Background Strict maintenance of normovolemia is standard of care in the treatment of aneurysmal subarachnoid hemorrhage (aSAH), and induced hypervolemia is often used to treat delayed cerebral ischemia from vasospasm. We tested the hypothesis that positive fluid balance could adversely affect clinical outcomes in aSAH. Methods We reviewed 288 patients with aSAH admitted to the Neuroscience Intensive Care Unit (NICU) from October 2001 to June 2011. We collected data on fluid balance during NICU stay, clinical and radiographic evidence of vasospasm, cardiopulmonary complications, and functional outcomes by modified Rankin Scale (mRS) on follow-up (mean 8 ± 8 months). Poor functional outcome was defined as an mRS score 3-6. Associations of variables of interest with outcome were assessed using univariable and multivariable logistic regression. Propensity scores were estimated to account for imbalances between patients with positive versus negative fluid balance and were included in multivariable models. Results Average net fluid balance during the NICU stay was greater in patients with poor functional outcome (3.52 ± 5.51 L versus -.02 ± 5.30 L in patients with good outcome; P <.001). On multivariate analysis, positive fluid balance (P =.002) was independently associated with poor functional outcome along with World Federation of Neurosurgical Societies grade (P <.001), transfusion (P =.003), maximum glucose (P =.005), and radiological evidence of cerebral infarction (P =.008). After regression adjustment with propensity scores, the association of positive fluid balance with poor functional outcome remained significant (odds ratio, 1.18; 95% confidence interval, 1.08-1.29; P <.001). Conclusions Greater positive net fluid balance is independently associated with poorer functional outcome in patients with aSAH.