Effects of plasmalyte A versus normal saline on brain relaxation and cerebral oxygenation in adult supratentorial tumor surgery: A randomized double-blind study

Background: Optimal fluid management during craniotomy for supratentorial tumor excision is critical. While 0.9% normal saline (NS) is conventionally used due to its osmolarity, balanced crystalloids like plasmalyte A (PA) may offer metabolic advantages. However, the superiority of one fluid over another is unknown. Methods: This prospective, randomized, double-blind trial enrolled 110 adult patients undergoing craniotomy for supratentorial tumors. Participants were randomized 1:1 to receive either NS or PA intraoperatively. The primary outcome was intraoperative brain relaxation assessed on a 4-point ordinal scale. Secondary outcomes included cerebral oxygenation parameters (jugular venous oxygen saturation, arteriovenous oxygen difference, cerebral oxygen extraction, cerebral metabolic rate of oxygen), hemodynamic stability, serum electrolytes, postoperative complications, hospital stay, and neurological status at discharge. Statistical analysis employed both Frequentist and Bayesian ordinal regression models. Results: Baseline characteristics were comparable between groups. The primary outcome showed no statistically significant difference in brain relaxation scores (odds ratio 0.56; 95% confidence interval 0.27–1.13; p = 0.107), but Bayesian analysis indicated a 95% posterior probability favoring PA. The risk of severe brain relaxation scores was lower in PA (14.6%) versus NS (23.6%), with a number needed to treat of 11. No significant differences were observed in cerebral oxygenation parameters or postoperative complications. Hospital length of stay and modified Rankin Scale scores at discharge were similar. Conclusion: PA and NS provide comparable intraoperative brain relaxation and postoperative outcomes in supratentorial tumor resection. Bayesian analysis suggests that PA may offer subtle benefits over NS in terms of intraoperative brain relaxation.