title: Detection of secondary insults by brain tissue pO2 and bedside microdialysis in severe head injury.
abstract: We evaluated bedside cerebral on-line microdialysis for early detection of cerebral hypoxia in patients with traumatic brain injury. 24 severely head injured patients (Glasgow Coma Score < or = 8) were studied. Patients underwent continuous brain tissue PO2 (PtiO2) monitoring using the LICOX (GMS mbH, Germany) microcatheter device. The catheter was placed into the non-lesioned frontal white matter within 32.2 (7-48) hrs post injury. The microdialysis catheter (CMA 100, Sweden) was placed close to the PtiO2 probe via a 2- or 3-way skull screw, connected to a pump and perfused with Ringer solution (0.3 microliter/min). The microdialysis samples were collected hourly and analyzed at the bedside for glucose, lactate, lactate-pyruvate-ratio and glutamate (CMA 600, Sweden). We identified 252 episodes of impending hypoxia (PtiO2 < 15 mm Hg; 11,810 minutes) and 38 episodes of cerebral hypoxia (PtiO2 < 10 mm Hg; 1996 minutes). Before cerebral hypoxia, glucose decreased significantly. Glutamate was unchanged when no hypoxia or impending hypoxia occurred but increased 3-4 fold before a hypoxic episode appeared. We conclude that early metabolic detection of cerebral hypoxia before a critical decrease in brain tissue PtiO2 is seen and possibly allows earlier changes in treatment (e.g. reduction of hyperventilation therapy).
authors.affiliation: Department of Neurosurgery, Charité Campus Virchow Medical Center, Humboldt University of Berlin, Germany.
authors.forename: A S
authors.initials: AS
authors.lastname: Sarrafzadeh
authors.forename: O W
authors.initials: OW
authors.lastname: Sakowitz
authors.forename: T A
authors.initials: TA
authors.lastname: Callsen
authors.forename: W R
authors.initials: WR
authors.lastname: Lanksch
authors.forename: A W
authors.initials: AW
authors.lastname: Unterberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D002648:Child; D006259:Craniocerebral Trauma / Q000150:complications / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D015600:Glasgow Coma Scale; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007427:Intracranial Pressure; D007773:Lactates / Q000378:metabolism; D008297:Male; D017551:Microdialysis / Q000379:methods; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D009928:Organ Specificity; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption; D010313:Partial Pressure; D019095:Point-of-Care Systems; D019289:Pyruvic Acid / Q000378:metabolism
chemical_list: D007773:Lactates; D019289:Pyruvic Acid; D005947:Glucose; D010100:Oxygen