Effective and safe mannitol administration in patients undergoing supratentorial tumor surgery: A prospective, randomized and double blind study

•The mannitol and furosemide-mannitol combination provides similar degree brain relaxation in supratentorial tumor surgery.•Furosemide with low or high doses of mannitol may cause electrolyte imbalance and high lactate levels.•Moreover high urine out-put and negative intra-operative fluid balance may occur.•0.5 g kg−1 mannitol provides enough brain relaxation without causing systemic side effects.

ObjectivesAlthough osmotic diuresis with mannitol is commonly used to provide brain relaxation, there is no consensus regarding its optimal dose and combination with loop diuretics. The aim of the present study is to evaluate the effects of mannitol and combination of furosemide with different doses of mannitol on brain relaxation and on blood electrolytes, lactate level, urine output, fluid balance and blood osmolarity in patients undergoing supratentorial tumor surgery.Patients and methodsThis prospective, randomized, double blind, placebo-controlled study included 51 patients (ASA I-III) scheduled for elective supratentorial craniotomy. Different doses and combinations of diuretics were administered after the bone flap removal. The Group 1 received mannitol at 0.5 g kg−1 and furosemide at 0.5 mg kg−1, the Group 2 received mannitol at 1 g kg−1 and furosemide at 0.5 mg kg−1, and the Group 3 received mannitol at 0.5 g kg−1 and placebo. The primary end-point of the present study is to evaluate the effects of mannitol and combination of furosemide with different doses of mannitol on brain relaxation and the secondary end-points are to evaluate their effects on blood electrolytes, lactate level, urine output, fluid balance and blood osmolarity.ResultsThis study shows that mannitol alone (0.5 g kg−1), and the combinations of furosemide (0.5 mg kg−1) with different doses of mannitol (0.5 g kg−1-1 g kg−1) provides adequate brain relaxation. However, administration of furosemide with low or high doses of mannitol may cause reduction in the sodium and chloride levels as well as rise in the lactate level. Moreover it may cause high urine output and negative intra-operative fluid balance.ConclusionAdministration of 0.5 g kg−1 mannitol provides adequate brain relaxation without causing systemic side effects in patients undergoing supratentorial tumor surgery.This study is registered to clinical trials (Clinical Trials.gov identifier NCT02712476).