title: Comparison between cerebral tissue oxygen tension and energy metabolism in experimental subdural hematoma.
abstract: BACKGROUND
  An experimental swine model (n = 7) simulating an acute subdural hematoma (ASDH) was employed (1) to explore the relation between the brain tissue oxygenation (PbtO(2)) and the regional cerebral energy metabolism as obtained by microdialysis, and (2) to define the lowest level of PbtO(2) compatible with intact energy metabolism.
  
  
  METHODS
  ASDH was produced by infusion of 7 ml of autologous blood (infusion rate 0.5 ml/min) by a catheter placed subdurally. PbtO(2) and microdialysis probes were placed symmetrically in the injured ("bad-side") and non-injured ("good-side") hemispheres. Intracranial pressure (ICP) was monitored in the "good-side."
  
  
  RESULTS
  ICP, cerebral perfusion pressure (CPP), PbtO(2), glucose, lactate, pyruvate, lactate-pyruvate ratio (LP ratio), glutamate, and glycerol were recorded at baseline (60 min) and post trauma (360 min). After the creation of the ASDH, PbtO(2) decreased significantly in both the hemispheres (P < 0.001). No significant difference was found between the sides post trauma. The LP ratio, glutamate, and glycerol in the "bad-side" increased significantly over the "good-side" where the values remained within the normal limits. A PbtO(2) value below approximately 25 mmHg was found to be associated with disturbed energy metabolism in the "bad-side" but not in the "good-side." No correlation was found between the LP ratio and PbtO(2) in either hemisphere.
  
  
  CONCLUSIONS
  PbtO(2) monitoring accurately describes tissue oxygenation but does not disclose whether the oxygen delivery is sufficient for maintaining cerebral energy metabolism. Accordingly, it may not be possible to define a threshold level for PbtO(2) below which energy failure and permanent tissue damage occurs.
authors.affiliation: Department of Neurosurgery, Odense University Hospital, Sdr. Boulevard 29, 5000 Odense C, Denmark. troels.halfeld.nielsen@ouh.regionsyddanmark.dk
authors.forename: Troels Halfeld
authors.initials: TH
authors.lastname: Nielsen
authors.forename: Susanne I
authors.initials: SI
authors.lastname: Engell
authors.forename: Rikke Aagaard
authors.initials: RA
authors.lastname: Johnsen
authors.forename: Mette K
authors.initials: MK
authors.lastname: Schulz
authors.forename: Oke
authors.initials: O
authors.lastname: Gerke
authors.forename: Jacob
authors.initials: J
authors.lastname: Hjelmborg
authors.forename: Palle
authors.initials: P
authors.lastname: Toft
authors.forename: Carl-Henrik
authors.initials: CH
authors.lastname: Nordström
mesh_terms: D000208:Acute Disease; D000818:Animals; D001921:Brain / Q000098:blood supply / Q000503:physiopathology; D002545:Brain Ischemia / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D046648:Hematoma, Subdural, Intracranial / Q000503:physiopathology*; D007427:Intracranial Pressure / Q000502:physiology; D010100:Oxygen / Q000032:analysis*; D012039:Regional Blood Flow / Q000502:physiology; D013552:Swine
chemical_list: D010100:Oxygen