Effect of equiosmolar solutions of mannitol versus hypertonic saline on intraoperative brain relaxation and electrolyte balance

Anesthesiology. 2007 Nov;107(5):697-704. doi: 10.1097/01.anes.0000286980.92759.94.


Background: The purpose of the study was to compare the effect of equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation and electrolyte balance.

Methods: After institutional review board approval and informed consent, patients with American Society of Anesthesiologists physical status II-IV, scheduled to undergo craniotomy for various brain pathologies, were enrolled into this prospective, randomized, double-blind study. Patients received 5 ml/kg 20% mannitol (n = 20) or 3% HS (n = 20). Partial pressure of carbon dioxide in arterial blood was maintained at 35-40 mmHg, and central venous pressure was maintained at 5 mmHg or greater. Hemodynamic variables, fluid balance, blood gases, electrolytes, lactate, and osmolality (blood, cerebrospinal fluid, urine) were measured at 0, 15, 30, and 60 min and 6 h after infusion; arteriovenous difference of oxygen, glucose, and lactate were calculated. The surgeon assessed brain relaxation on a four-point scale (1 = relaxed, 2 = satisfactory, 3 = firm, 4 = bulging). Appropriate statistical tests were used for comparison; P < 0.05 was considered significant.

Results: There was no difference in brain relaxation (mannitol = 2, HS = 2 points; P = 0.8) or cerebral arteriovenous oxygen and lactate difference between HS and mannitol groups. Urine output with mannitol was higher than with HS (P < 0.03) and was associated with higher blood lactate over time (P < 0.001, compared with HS). Cerebrospinal fluid osmolality increased at 6 h in both groups (P < 0.05, compared with baseline). HS caused an increase in sodium in cerebrospinal fluid over time (P < 0.001, compared with mannitol).

Conclusion: Mannitol and HS cause an increase in cerebrospinal fluid osmolality, and are associated with similar brain relaxation scores and arteriovenous oxygen and lactate difference during craniotomy.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / drug effects
  • Brain / drug effects*
  • Craniotomy / methods
  • Diuretics, Osmotic / pharmacology*
  • Double-Blind Method
  • Female
  • Humans
  • Intracranial Pressure / drug effects*
  • Intraoperative Care / methods
  • Lactic Acid / blood
  • Lactic Acid / cerebrospinal fluid
  • Male
  • Mannitol / pharmacology*
  • Middle Aged
  • Osmolar Concentration
  • Oxygen / blood
  • Potassium / blood
  • Prospective Studies
  • Saline Solution, Hypertonic / pharmacology*
  • Sodium / cerebrospinal fluid
  • Time Factors
  • Water-Electrolyte Balance / drug effects*


  • Blood Glucose
  • Diuretics, Osmotic
  • Saline Solution, Hypertonic
  • Lactic Acid
  • Mannitol
  • Sodium
  • Potassium
  • Oxygen