Effect of mannitol and hypertonic saline on cerebral oxygenation in patients with severe traumatic brain injury and refractory intracranial hypertension.
BACKGROUND
The impact of osmotic therapies on brain oxygen has not been extensively studied in humans. We examined the effects on brain tissue oxygen tension (PbtO(2)) of mannitol and hypertonic saline (HTS) in patients with severe traumatic brain injury (TBI) and refractory intracranial hypertension.


METHODS
12 consecutive patients with severe TBI who underwent intracranial pressure (ICP) and PbtO(2) monitoring were studied. Patients were treated with mannitol (25%, 0.75 g/kg) for episodes of elevated ICP (>20 mm Hg) or HTS (7.5%, 250 ml) if ICP was not controlled with mannitol. PbtO(2), ICP, mean arterial pressure, cerebral perfusion pressure (CPP), central venous pressure and cardiac output were monitored continuously.


RESULTS
42 episodes of intracranial hypertension, treated with mannitol (n = 28 boluses) or HTS (n = 14 boluses), were analysed. HTS treatment was associated with an increase in PbtO(2) (from baseline 28.3 (13.8) mm Hg to 34.9 (18.2) mm Hg at 30 min, 37.0 (17.6) mm Hg at 60 min and 41.4 (17.7) mm Hg at 120 min; all p<0.01) while mannitol did not affect PbtO(2) (baseline 30.4 (11.4) vs 28.7 (13.5) vs 28.4 (10.6) vs 27.5 (9.9) mm Hg; all p>0.1). Compared with mannitol, HTS was associated with lower ICP and higher CPP and cardiac output.


CONCLUSIONS
In patients with severe TBI and elevated ICP refractory to previous mannitol treatment, 7.5% hypertonic saline administered as second tier therapy is associated with a significant increase in brain oxygenation, and improved cerebral and systemic haemodynamics.
Oddo
M
M
Neurointensive Care Unit, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA.
Levine
J M
JM
Frangos
S
S
Carrera
E
E
Maloney-Wilensky
E
E
Pascual
J L
JL
Kofke
W A
WA
Mayer
S A
SA
LeRoux
P D
PD
D000328:Adult; D001923:Brain Chemistry / Q000187:drug effects*; D001930:Brain Injuries / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism; D003627:Data Interpretation, Statistical; D004232:Diuretics / Q000494:pharmacology*; D005260:Female; D015600:Glasgow Coma Scale; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D019586:Intracranial Hypertension / Q000188:drug therapy* / Q000209:etiology; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D008353:Mannitol / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*; D012008:Recurrence; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*
D004232:Diuretics; D012462:Saline Solution, Hypertonic; D008353:Mannitol