Hyperosmolar Therapy in Elderly Neurosurgical Patients: Comparison of the Effect of Mannitol (20%) and Hypertonic Saline (3%) on Advanced Cardiovascular Parameters Using Transesophageal Echocardiography: A Preliminary Randomized Controlled Trial

Abstract

Osmotherapeutic agents increase the intravascular volume by withdrawing water from the brain followed by relative hypovolemia due to diuresis leading to significant changes in systemic hemodynamics which might have adverse consequences in the elderly. We studied the effect of mannitol (20%) and hypertonic saline (HTS) (3%) on left ventricular outflow tract velocity time integral (LVOT-VTI) and cardiac output (CO) in elderly patients undergoing supratentorial neurosurgical procedures using transesophageal echocardiography. We recruited 28 patients aged above 65years undergoing supratentorial craniotomy who received equiosmolar solutions of 5.35ml/kg of 3% HTS (group HS, n= 14) or 5ml/kg of 20% mannitol (group M, n= 14). LVOT-VTI was recorded at baseline, 15, 30, 45, 60, and 90minutes postinfusion and CO was derived. We also recorded heart rate, blood pressure, fluid balance, brain relaxation, vasopressor use, complications, and neurological outcome. We found a significant decrease in LVOT-VTI at 45, and 60minutes in group M as compared to group HS [mean (standard deviation), 16.76 (1.81) vs. 20.78 (1.87), P<0.001, 17.4 (2.38) vs. 19.16 (2), P=0.044, respectively]. We also found a corresponding significant fall in CO [3863.16 (845.87) vs. 4745.59 (1209.33) ml/minute, P=0.034] and systolic blood pressure (P=0.039), at 45minutes in group M. Urine output was higher in group M (P<0.001). All other parameters were comparable. HTS appears to be associated with better systemic hemodynamics (LVOT-VTI, CO) while providing equivalent brain relaxation as mannitol in elderly patients. A future larger study is required to confirm our preliminary findings.