Recommended Dosage of Mannitol for Raised Intracranial Pressure
For raised intracranial pressure, mannitol should be administered at a dose of 0.25 to 2 g/kg body weight as a 15% to 25% solution, infused rapidly over 5 to 30 minutes. 1
Dosing Guidelines Based on Patient Population
- Adults: 0.25 to 2 g/kg body weight as a 15% to 25% solution administered over 30 to 60 minutes 1
- Pediatric patients: 1 to 2 g/kg body weight or 30 to 60 g/m² body surface area over 30 to 60 minutes 1
- Small or debilitated patients: A lower dose of 500 mg/kg may be sufficient 1
Administration Considerations
- Mannitol should be administered as a bolus infusion rather than continuous infusion for acute management of raised ICP 2
- The solution should be infused rapidly over 5 to 30 minutes to achieve maximum effect 2
- Effects on ICP typically peak at around 44 minutes (range 18-120 minutes) after administration 3
- Doses of 1.0 g/kg or higher consistently reduce ICP by at least 10%, while doses below this threshold may not always be effective 3
Monitoring and Precautions
- Insert a Foley catheter before administration due to mannitol's potent diuretic effect 2
- Monitor serum osmolality frequently and maintain below 320 mOsm to avoid renal failure 2
- Evaluate circulatory and renal reserve prior to administration, especially at higher doses 1
- Evidence of reduced cerebral spinal fluid pressure should be observed within 15 minutes after starting infusion 1
- The short-term effect of mannitol means repeated doses may be necessary 4
Special Considerations
- In cases of cerebral malaria in children, mannitol 0.5 mg/kg infused rapidly over 5-10 minutes may be effective in lowering intracranial pressure 4
- 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 with a usual maximal dose of 2 g/kg 4
- Initial smaller doses (0.25-0.5 g/kg) may be as effective as larger doses for acute ICP reduction, while avoiding risks of osmotic disequilibrium and severe dehydration 5
- Excessive cumulative dosing may lead to larger doses being required for subsequent ICP control 6
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
- Known hypersensitivity to mannitol 1
Alternative Therapies
- 3% hypertonic saline has shown promising results compared to mannitol in some studies, particularly in pediatric CNS infections 7
- Other forms of osmotherapy for raised ICP management, such as hypertonic saline, have not been extensively evaluated in all patient populations 4
Remember that mannitol is a temporizing measure for raised ICP and should be part of a comprehensive management approach that may include airway management, mechanical ventilation, and close monitoring of blood gases 4.