Mannitol revisited.

Investigation into the use of osmotic therapy for ICP reduction began in 1919. Mannitol is the osmotic agent currently in use. Mannitol's effectiveness in reducing ICP has been shown. Osmotic therapy using mannitol reduces ICP by mechanisms that remain unclear. Mannitol is thought to decrease brain volume by decreasing overall water content, to reduce blood volume by vasoconstriction and to reduce CSF volume by decreasing water content. Mannitol may also improve cerebral perfusion by decreasing viscosity or altering red blood cell rheology. Lastly, mannitol may exert a protective effect against biochemical injury. The most common complications of therapy are fluid and electrolyte imbalances, cardiopulmonary edema and rebound cerebral edema. Nursing care of the patient receiving mannitol requires vigilant monitoring of electrolytes and overall fluid balance, and observation for the development of cardiopulmonary complications in addition to neurologic assessment.