What are the administration guidelines and potential complications of mannitol (osmotic diuretic) in a patient?

Mannitol Administration Guidelines and Potential Complications

Mannitol should be administered at a dose of 0.25-2 g/kg body weight as a 15-25% solution, infused over 30-60 minutes for reducing intracranial pressure, with careful monitoring of fluid and electrolyte balance to prevent complications. 1

Dosing and Administration

• For adults, the recommended dose is 0.25-2 g/kg as a 15-25% solution administered over 30-60 minutes; for pediatric patients, 1-2 g/kg or 30-60 g/m² over the same timeframe 1
• In small or debilitated patients, a lower dose of 500 mg/kg may be sufficient 1
• Mannitol should be infused at 250 mOsm over 15-20 minutes when treating threatened intracranial hypertension or signs of brain herniation 2
• Evidence of reduced intracranial pressure should be observed within 15 minutes after starting infusion 1

Clinical Indications

• Mannitol is indicated for reduction of intracranial pressure, brain mass, and intraocular pressure 1
• It is the treatment of choice for signs of brain herniation (mydriasis, anisocoria) or neurological worsening not attributable to systemic causes 2
• Among therapies that decrease intracranial pressure, only mannitol has been associated with improved cerebral oxygenation 2

Monitoring Requirements

• Careful evaluation of circulatory and renal reserve is essential prior to and during administration, especially at higher doses and rapid infusion rates 1
• Serum osmolality should be monitored to ensure it remains below 320 mOsm/L 3
• Close attention must be paid to fluid and electrolyte balance, body weight, and total input and output before and after infusion 1
• Serum sodium and potassium levels should be carefully monitored during mannitol administration 1

Potential Complications

Renal Complications

• Renal complications, including irreversible renal failure, have been reported in patients receiving mannitol 1
• Reversible, oliguric acute kidney injury can occur even in patients with normal pretreatment renal function 1
• Osmotic nephrosis (reversible vacuolization of tubules) may progress to severe irreversible nephrosis 1
• Acute renal failure is more likely with massive mannitol infusion (400-900 g/day) 4
• Risk factors include pre-existing renal disease and concomitant use of nephrotoxic drugs or other diuretics 1

Fluid and Electrolyte Imbalances

• The obligatory diuretic response following rapid infusion may aggravate pre-existing hemoconcentration 1
• Excessive loss of water and electrolytes can lead to serious imbalances 1
• With continued administration, loss of water in excess of electrolytes can cause hypernatremia 1
• The shift of sodium-free intracellular fluid into the extracellular compartment may lower serum sodium concentration and aggravate pre-existing hyponatremia 1
• Sustained diuresis may obscure and intensify inadequate hydration or hypovolemia 1

Cardiovascular Complications

• Accumulation of mannitol may result in overexpansion of the extracellular fluid, which may intensify existing or latent congestive heart failure 1
• Sudden expansion of the extracellular fluid may lead to fulminating congestive heart failure 1

Central Nervous System Complications

• Mannitol may increase cerebral blood flow and the risk of postoperative bleeding in neurosurgical patients 1
• It may worsen intracranial hypertension in children who develop generalized cerebral hyperemia during the first 24-48 hours post-injury 1

Special Considerations

• At equiosmotic doses, mannitol and hypertonic saline have comparable efficacy in treating intracranial hypertension 2
• While mannitol induces osmotic diuresis and requires volume compensation, hypertonic saline exposes patients to hypernatremia and hyperchloremia 2
• When treating elevated intracranial pressure with mannitol, cerebral perfusion pressure should be maintained between 60-70 mmHg 3
• Do not administer 25% mannitol if the fliptop vial seal is not intact 1
• When exposed to low temperatures, solutions of mannitol may crystallize; if crystals are observed, the container should be warmed to redissolve, then cooled to body temperature before administering 1
• When infusing 25% mannitol, the administration set should include a filter 1

Contraindications

• Mannitol should be administered carefully and is contraindicated in patients with oligoanuria 2
• Never add mannitol in whole blood for transfusion 1
• Do not place 25% Mannitol Injection in polyvinylchloride (PVC) bags as a white flocculent precipitate may form 1