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Variation in osmotic response to sustained mannitol administration.

Salah G Keyrouz1, Rajat Dhar, Michael N Diringer

  • 1Department of Neurology and Neurological Surgery, Washington University, St. Louis, MO, 63110, USA.

Neurocritical Care
|June 20, 2008
PubMed
Summary

Many patients do not achieve the expected osmotic response to mannitol therapy for cerebral edema. Younger age, lower mannitol dose, and negative fluid balance are linked to this lack of response, suggesting alternative treatments may be needed.

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Area of Science:

  • Neurology
  • Neurosurgery
  • Critical Care Medicine

Background:

  • Mannitol is a primary osmotic agent for managing cerebral edema and intracranial pressure.
  • A subset of patients exhibits a diminished osmotic response to sustained mannitol administration, potentially impacting therapeutic outcomes.

Purpose of the Study:

  • To investigate the variability in osmotic response to mannitol therapy.
  • To identify factors associated with a lack of osmotic response in patients receiving sustained mannitol.

Main Methods:

  • A prospective database of 167 Neurology/Neurosurgery Intensive Care Unit patients receiving mannitol for ≥48 hours was analyzed.
  • Serum sodium and osmolality were monitored serially, with non-responders defined by serum sodium rise thresholds (< or =1 mEq/l or < or =5 mEq/l over 48 hours).

Main Results:

  • 44% of patients (73/167) did not achieve a serum sodium rise of ≥5 mEq/l, and 22% (37/167) did not achieve a ≥1 mEq/l rise over 48 hours.
  • Multivariate analysis indicated that younger age, lower weight-adjusted mannitol dose, and a more negative fluid balance were associated with a lack of osmotic response.

Conclusions:

  • A significant portion of patients on sustained mannitol do not show the anticipated osmotic response.
  • This lack of response may correlate with reduced clinical efficacy, highlighting the need for alternative agents like hypertonic saline in some patients.