Furosemide- and Mannitol-induced Changes in Intracranial Pressure and Serum Osmolality and Electrolytes

Abstract

The effects of furosemide and mannitol on intracranial pressure (ICP), serum osmolality and electrolytes were measured preoperatively, after induction of anesthesia, at the onset and peak of diuresis, at the completion of diuresis, and postoperatively. After mannitol, ICP increased significantly at the onset of diuresis (15.7 .+-. 4 torr) and decreased significantly at the completion of diuresis (7.25 .+-. 2.4 torr), and postoperatively (6.1 .+-. 2.4 torr). After furosemide, ICP decreased at peak diuresis (5.4 .+-. 1.4 torr), at completion of diuresis (4.7 .+-. 1.7 torr), and postoperatively (2.6 .+-. 1.3 torr). Serum osmolality increased significantly following mannitol at onset (302.1 .+-. 4.4 mOsm [milliosmol]), peak (299.8 .+-. 2.2 mOsm), and completion of diuresis (296 .+-. 2.3 mOsm), and postoperatively (294.1 .+-. 2.4 mOsm). Furosemide did not significantly alter serum osmolality or electrolyte values. After mannitol, serum K was significantly decreased at the end of diuresis (4.0 .+-. 0.2 meq/l) and postoperatively (3.9 .+-. 0.2 meq/l), while serum Na was decreased significantly at the onset (132.4 .+-. 1.3 meq/l), peak (133.8 .+-. 1.1 meq/l), and completion of diuresis (134.9 .+-. 0.8 meq/l) and postoperatively (135.8 .+-. 0.9 meq/l). Because of these changes, it is recommended that furosemide be used instead of mannitol when diuresis is desired in patients with increased ICP, and in those who have pre-existing cardiac and electrolyte abnormalities.