Mannitol for Traumatic Brain Injury with Elevated Intracranial Pressure

Primary Benefits and Mechanism

The American College of Anaesthesia recommends mannitol 20% at 0.25-2 g/kg administered over 15-20 minutes for treating threatened intracranial hypertension or signs of brain herniation in traumatic brain injury, as it effectively reduces ICP, improves cerebral oxygenation, and restores cerebral blood flow 1, 2, 3, 4
Mannitol reduces intracranial pressure by creating an osmotic gradient across the blood-brain barrier, drawing water from brain tissue into the hypertonic vascular space, with maximum effect occurring at 10-15 minutes and lasting 2-4 hours 1, 2, 3, 4
Mannitol uniquely improves cerebral oxygenation among the three therapies that decrease ICP (mannitol, external ventricular drainage, and hyperventilation) 1, 2, 3, 4
Mannitol restores cerebral blood flow through reduction of brain mass and improved cerebral perfusion pressure 1, 2, 3, 4

The European guidelines recommend using mannitol for documented or threatened intracranial hypertension after controlling secondary brain insults (Grade 1+ recommendation) 1, 2, 3, 4
Mannitol is effective for emergency treatment of patients with signs of brain herniation (mydriasis, anisocoria) and/or neurological worsening not attributable to systemic causes 1, 2, 3, 4
When hypernatremia is already present, choose mannitol over hypertonic saline in this scenario 5

Mannitol and hypertonic saline have comparable efficacy at equiosmotic doses (250 mOsm): both agents effectively reduce ICP with similar mortality outcomes 1, 2, 3, 4, 5
Mannitol uniquely improves cerebral oxygenation among the three therapies that decrease ICP (mannitol, external ventricular drainage, and hyperventilation) 1, 2, 3, 4, 5

Monitor fluid, sodium, and chloride balances as mannitol induces osmotic diuresis requiring volume compensation 1, 2, 3, 4, 5

Do NOT use prophylactically - prophylactic administration to patients without evidence of intracranial hypertension is not recommended 1, 2, 3, 4, 5
Maximum daily dose: 2 g/kg to avoid adverse effects 5

Common adverse effects requiring monitoring: osmotic diuresis with potential hypovolemia and hypotension, electrolyte imbalances (hypernatremia, hyponatremia), dehydration, pulmonary congestion, and thrombophlebitis at infusion site 3, 5

The recommendation for mannitol carries Grade 1+ with Strong Agreement from European guidelines 1, 2, 3, 4