What are the considerations for using mannitol in patients undergoing hemodialysis?

Mannitol Use in Hemodialysis Patients: Considerations and Recommendations

Mannitol should be used with extreme caution in hemodialysis patients due to risk of accumulation and potential toxicity, and is generally not recommended for routine use in this population. 1, 2

Pharmacokinetics in Hemodialysis

• Mannitol is primarily eliminated by the kidneys with approximately 80% of a dose appearing in urine within 3 hours in patients with normal renal function 1
• In patients with end-stage renal failure, the elimination half-life of mannitol is significantly prolonged to approximately 36 hours 1, 2
• During hemodialysis, the half-life is reduced to about 6 hours, which is still considerably longer than in patients with normal renal function 1, 2

Potential Indications in Hemodialysis Patients

• Mannitol may be considered for management of intradialytic hypotension (IDH) due to its oncotic effect that increases plasma osmolality to maintain adequate blood pressure 3
• It has been used to decrease the incidence of dialysis disequilibrium syndrome symptoms by reducing the osmolality fall during hemodialysis 4, 5
• Historically, it has been used to maintain urine output in patients newly initiated on hemodialysis who still have residual kidney function 6

Risks and Contraindications

• Mannitol is contraindicated in patients with:
  • Severe dehydration 1
  • Progressive heart failure or pulmonary congestion 1
  • Severe pulmonary edema 1
• Mannitol can cause significant fluid and electrolyte imbalances, particularly:
  • Hypernatremia due to free water loss exceeding sodium loss 7
  • Electrolyte abnormalities requiring close monitoring 8
• Risk of mannitol accumulation and toxicity is high in hemodialysis patients, manifesting as:
  • CNS involvement disproportionate to uremia 2
  • Severe hyponatremia 2
  • Large osmolality gap (high measured minus calculated serum osmolality) 2
  • Fluid overload 2

Monitoring Requirements

• Serum electrolytes, particularly sodium and potassium, should be closely monitored 8
• Renal function tests including BUN and creatinine should be monitored 8
• Acid-base status should be assessed through arterial blood gases 8
• Serum osmolality should be maintained below 320 mOsm/L during mannitol therapy 7
• Cardiovascular status should be monitored for signs of fluid overload 1

Clinical Recommendations

• For patients requiring mannitol who are on hemodialysis:
  • Use the lowest effective dose possible 1
  • Consider more frequent or extended dialysis sessions to remove accumulated mannitol 2
  • Monitor for signs of mannitol toxicity including altered mental status, hyponatremia, and fluid overload 2
• Hemodialysis is the preferred method for treating mannitol toxicity as it rapidly removes mannitol (half-life of 6 hours during dialysis) 2
• Peritoneal dialysis is less effective at removing mannitol (half-life of 21 hours) 2
• Avoid routine prophylactic use of mannitol without close laboratory monitoring 8

Alternative Approaches

• For volume management in hemodialysis patients, appropriate ultrafiltration techniques and dietary sodium restriction are preferred over mannitol 9
• For preservation of residual kidney function in hemodialysis patients, other methods should be considered as diuretic use should be approached with caution 9
• For management of intracranial hypertension, hypertonic saline may be considered as an alternative with different side effect profile 7

Pitfalls to Avoid

• Avoid concomitant administration of mannitol with nephrotoxic drugs or other diuretics 1
• Do not use mannitol solely for the purpose of renal protection 9
• Be aware that mannitol can obscure and intensify inadequate hydration or hypovolemia 1
• Recognize that accumulation of mannitol may worsen existing or latent congestive heart failure 1
• Discontinue mannitol if renal, cardiac, or pulmonary status worsens 1