Comparison of Effects of Intravenous 20% Mannitol versus Combination of 10% Mannitol and 10% Glycerol for Intraoperative Brain Relaxation in Neurosurgery

Background: Pharmacological reduction in intraoperative brain bulk is commonly achieved using mannitol. Other hyperoncotic agents like glycerol are less frequently used due to reported intravascular hemolysis and hyperglycemia. A combination of glycerol 10% and mannitol 10% may limit the adverse effects of both agents. The study's objective was to compare the impact of mannitol 20% and the combination on intraoperative brain relaxation and their adverse effects. Methods: Sixty adult patients undergoing elective supratentorial tumor removal by craniotomy were randomized to receive either 2.5 mL /kg of 20% mannitol (group M) or 10% mannitol + 10% glycerol (group C). Brain relaxation was assessed on the four-point scale after craniotomy, and hemodynamics, electrolyte, and blood sugar were measured up to 1 hour after infusion. Results: Seventy-nine percent of patients in group M and 93% in group C had adequate brain relaxation (scale1 and 2; p = 0.108) There was no significant difference in hemodynamic and electrolyte changes. There was a significant increase in blood glucose in group C (mean: 13.1 mg% (standard deviation: 4.4). There was no difference in the length of intensive care unit and hospital stay. None of the patients had hemolysis or clinical evidence of rebound edema. There was no mortality in the groups. Conclusion: The combination of 10% mannitol and 10% glycerol provides a safe and effective alternative to 20% mannitol for intraoperative reduction in intracranial pressure and reduction in brain bulk for providing suitable conditions for the removal of supratentorial tumors.