title: Association between elevated brain tissue glycerol levels and poor outcome following severe traumatic brain injury.
abstract: OBJECTIVE
  Glycerol is considered to be a marker of cell membrane degradation and thus cellular lysis. Recently, it has become feasible to measure via microdialysis cerebral extracellular fluid (ECF) glycerol concentrations at the patient's bedside. Therefore the aim of this study was to investigate the ECF concentration and time course of glycerol after severe traumatic brain injury (TBI) and its relationship to patient outcome and other monitoring parameters.
  
  
  METHODS
  As soon as possible after injury for up to 4 days, 76 severely head-injured patients were monitored using a microdialysis probe (cerebral glycerol) and a Neurotrend sensor (brain tissue PO2) in uninjured brain tissue confirmed by computerized tomography scanning. The mean brain tissue glycerol concentration in all monitored patients decreased significantly from 206 +/- 31 micromol/L on Day 1 to 9 +/- 3 micromol/L on Day 4 after injury (p < 0.0001). Note, however, that there was no significant difference in the time course between patients with a favorable outcome (Glasgow Outcome Scale [GOS] Scores 4 and 5) and those with an unfavorable outcome (GOS Scores 1-3). Significantly increased glycerol concentrations were observed when brain tissue PO2 was less than 10 mm Hg or when cerebral perfusion pressure was less than 70 mm Hg.
  
  
  CONCLUSIONS
  Based on results in the present study one can infer that microdialysate glycerol is a marker of severe tissue damage, as seen immediately after brain injury or during profound tissue hypoxia. Given that brain tissue glycerol levels do not yet add new clinically significant information, however, routine monitoring of this parameter following traumatic brain injury needs further validation.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Clausen
authors.forename: Oscar Luis
authors.initials: OL
authors.lastname: Alves
authors.forename: Michael
authors.initials: M
authors.lastname: Reinert
authors.forename: Egon
authors.initials: E
authors.lastname: Doppenberg
authors.forename: Alois
authors.initials: A
authors.lastname: Zauner
authors.forename: Ross
authors.initials: R
authors.lastname: Bullock
mesh_terms: D000328:Adult; D015415:Biomarkers; D001923:Brain Chemistry; D001930:Brain Injuries / Q000473:pathology*; D005260:Female; D005990:Glycerol / Q000032:analysis*; D006801:Humans; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D005990:Glycerol