A patient with a head injury that is resulting in edema (swelling) of the brain is given an intravenous solution that contains mannitol, a polar sugar-alcohol. how can this solute be beneficial in reducing the edema of the brain?

Mannitol reduces the intracranial hypertension in patients with head injury. this chemical which is a sugar - alcohol lowers the viscosity of the blood and thus reducing the blood volume. Head injury may lead to increased intracranial pressure and volume. It is also believed that mannitol acts by reducing brain water.