Compare mannitol and hypertonic saline in managing cerebral edema.

• A. Both are hyperosmolar therapies; mannitol creates osmotic gradient; hypertonic saline reduces ICP and expands intravascular volume; monitor osmolality and sodium
• B. Mannitol reduces ICP but hypertonic saline does not
• C. Hypertonic saline increases ICP
• D. Mannitol and hypertonic saline have identical mechanisms

Answer: (A)

Both mannitol and hypertonic saline reduce intracranial pressure by making the blood plasma more concentrated, so water shifts out of swollen brain tissue into the vascular space. Mannitol works by increasing plasma osmolality, creating an osmotic gradient that pulls water from cerebral cells into the bloodstream. Hypertonic saline also raises serum osmolality, but it has the added effect of expanding intravascular volume, which can support blood pressure and cerebral perfusion in patients who are hypotensive or volume-depleted.

Because both therapies raise osmolality, careful monitoring is essential. Check serum osmolality and sodium to avoid dangerous shifts—mannitol can cause diuresis and dehydration, while hypertonic saline can lead to hypernatremia and fluid overload. In short, they’re both hyperosmolar treatments for cerebral edema, with mannitol mainly creating an osmotic gradient and hypertonic saline both reducing ICP and expanding intravascular volume; monitoring osmolar status and sodium is key for safe use.