Mannitol Dosage for Reducing Intracranial Pressure
For treatment of increased intracranial pressure (ICP), mannitol should be administered at a dose of 0.25 to 2 g/kg body weight as a 15% to 25% solution over 30 to 60 minutes. 1
Adult Dosing
- For ischemic brain swelling, mannitol is typically used at 0.25 to 0.5 g/kg IV administered over 20 minutes and can be given every 6 hours 2
- The usual maximal dose is 2 g/kg 2, 1
- In acute intracranial hypertensive crisis, larger doses (0.5 g/kg given over 15 minutes) may be appropriate 2
Pediatric Dosing
- For children: 1 to 2 g/kg body weight or 30 to 60 g/m² body surface area over 30 to 60 minutes 1
- For small or debilitated patients: 500 mg/kg 1
Administration Protocol
- Administer as an intravenous bolus over 15-30 minutes 2, 3
- Mannitol should be administered through a filter; do not use solutions that contain crystals 2
- Research suggests that rapid administration (2 ml/kg/min) produces higher peak serum concentrations and more profound lowering of ICP than slower rates 4
Monitoring and Precautions
- A urine-collecting catheter should be placed when using mannitol 2
- Monitor for hyperosmolality; discontinue when serum osmolality exceeds 320 mOsm/L 5
- Serum osmolality rises of 10 mOsm or more are associated with a reduction in ICP 6
- Stop treatment after 2-4 doses or when there is no clinical improvement 3
- Avoid concomitant administration of nephrotoxic drugs 1
Efficacy Considerations
- Studies show that smaller doses (0.25 g/kg) can be as effective as larger doses (0.5-1 g/kg) in acutely reducing ICP 6
- Smaller and more frequent doses may be as effective in reducing ICP while avoiding risks of osmotic disequilibrium and severe dehydration 6
- The effect of mannitol on ICP reduction is dose-dependent during the period of ICP reduction but reaches a "mannitol saturation dosage" after ICP has reached a fixed level 7
Comprehensive Management
- In conjunction with mannitol, other measures to control ICP should be considered, including hyperventilation, sedation/analgesia, head-of-bed elevation, cerebrospinal fluid drainage, barbiturates, and muscle relaxation 2
- Mannitol is a temporizing measure for raised ICP and should be part of a comprehensive management approach 3
- Consider surgical decompression when medical management fails 3
Contraindications
- Well-established anuria due to severe renal disease 1
- Severe pulmonary congestion or frank pulmonary edema 1
- Active intracranial bleeding except during craniotomy 1
- Severe dehydration 1
- Progressive heart failure or pulmonary congestion after institution of mannitol therapy 1
Remember that mannitol is a temporizing measure in the management of increased ICP, and its use should be accompanied by other appropriate interventions based on the underlying cause of the increased pressure.