Intracranial and systemic effects of osmotic and oncotic therapy in experimental cerebral edema

Experiments were carried out to compare the effectiveness of oncotic and osmotic therapy in dogs with experimental cerebral edema caused by a left parietal cold lesion. Animals were divided into five groups and treated for 6 hours with either crystalloid (control group), or mannitol, albumin, furosemide, or albumin/furosemide (treatment groups). The cerebral effects of therapy were evaluated by intracranial pressure (ICP) measurements and by postmortem evaluations of water content, using computerized tomography (CT) density measurements and wet-dry weight measurements. The ICP was significantly reduced by all treatments except albumin alone, and was reduced equally by mannitol, furosemide, and albumin/furosemide. The CT density of the lesion area was significantly increased by all treatments. The density of the contralateral nonlesioned hemisphere was significantly increased by all treatments except albumin. The water content of the lesion area was significantly decreased by all treatments; water content of the opposite hemisphere was not significantly reduced. The systemic effects of therapy were evaluated by measuring net fluid balance, wedge pressures, hematocrits, free water clearance, and vasopressin. Negative fluid balance without an increase in hematocrit or in vasopressin secretion occurred only in dogs treated with albumin/furosemide. Such oncodiuretic therapy seems to cause normovolemic dehydration and to have cerebral effects similar to mannitol and furosemide, without their undesirable systemic effects.