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


CONCLUSIONS
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.
Rozet
Irene
I
Department of Anesthesiology, Harborview Medical Center, University of Washington, Seattle 98104, USA. irozet@u.washington.edu
Tontisirin
Nuj
N
Muangman
Saipin
S
Vavilala
Monica S
MS
Souter
Michael J
MJ
Lee
Lorri A
LA
Kincaid
M Sean
MS
Britz
Gavin W
GW
Lam
Arthur M
AM
D001786:Blood Glucose / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D003399:Craniotomy / Q000379:methods; D004234:Diuretics, Osmotic / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000187:drug effects*; D007430:Intraoperative Care / Q000379:methods; D019344:Lactic Acid / Q000097:blood / Q000134:cerebrospinal fluid; D008297:Male; D008353:Mannitol / Q000494:pharmacology*; D008875:Middle Aged; D009994:Osmolar Concentration; D010100:Oxygen / Q000097:blood; D011188:Potassium / Q000097:blood; D011446:Prospective Studies; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012964:Sodium / Q000134:cerebrospinal fluid; D013997:Time Factors; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D001786:Blood Glucose; D004234:Diuretics, Osmotic; D012462:Saline Solution, Hypertonic; D019344:Lactic Acid; D008353:Mannitol; D012964:Sodium; D011188:Potassium; D010100:Oxygen