Management of Intracranial Pressure in Intracerebral Hemorrhage

Indications for Mannitol

The American Heart Association/American Stroke Association recommends mannitol for reduction of intracranial pressure and brain mass in patients with clinical evidence of elevated intracranial pressure (ICP) 1, 2
Clinical signs of elevated ICP requiring mannitol treatment include neurological deterioration, pupillary abnormalities, decerebrate posturing, and directly measured elevated ICP (>20-25 mmHg) in monitored patients 3, 1
Mannitol is not recommended for routine or prophylactic use in all ICH patients without evidence of increased ICP, as stated by the European Stroke Organisation 4

Typical clinical administration of mannitol involves 0.25 to 0.5 g/kg IV administered over 20 minutes, which can be given every 6 hours as needed, with a maximum dose of 2 g/kg 5, 2, 6

Mannitol creates an osmotic gradient across the blood-brain barrier, causing water displacement from brain tissue to the intravascular space, with maximum effect occurring after 10-15 minutes and lasting for 2-4 hours 3
A single bolus of mannitol modifies cerebral hemodynamics by increasing flow velocities in the affected middle cerebral artery in ICH patients 2

Serum osmolality should be monitored and maintained below 320 mOsm/L, and mannitol is contraindicated in severe pulmonary congestion or frank pulmonary edema, and severe dehydration 3, 5

The 2022 AHA/ASA guidelines note that hyperosmolar therapy (including mannitol) is the principal medical strategy for treating cerebral edema, but the duration of effects in ICH is unclear 1, 2
The European Stroke Organisation guidelines note insufficient evidence from RCTs to make strong recommendations on measures to lower ICP for adults with acute ICH 4