title: The effect of red blood cell transfusion on cerebral oxygenation and metabolism after severe traumatic brain injury.
abstract: OBJECTIVE
  There is evidence to suggest that anemia after severe traumatic brain injury (sTBI) is detrimental. However, there is a paucity of evidence supporting the use of transfusion of packed red blood cells in patients with sTBI. To understand the acute effect of packed red blood cell transfusion on cerebral oxygenation and metabolism in patients with sTBI.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Addenbrooke's Neurosciences Critical Care Unit, a 21-bed tertiary academic unit.
  
  
  METHODS
  Thirty patients with sTBI.
  
  
  METHODS
  Patients were randomized by computer random number generator to one of three transfusion thresholds: 8, 9, or 10 g/dL. When the patients' hemoglobin concentration fell below their assigned threshold, two units of packed red blood cells were transfused over 2 hours. A 1-hour period of stabilization was observed before final data collection.
  
  
  RESULTS
  The primary outcome was change in brain tissue oxygen (Pbto2). Secondary outcomes included dependence of baseline hemoglobin concentration and baseline Pbto2 on the relationship of transfusion and Pbto2, and the effect of transfusion on lactate pyruvate ratio (LPR) and brain pH as markers of cerebral metabolic state. Fifty-seven percent of patients experienced an increase in Pbto2 during the course of the study, whereas in 43% of patients, Pbto2 either did not change or decreased. Multivariable generalized estimating equation analysis revealed change in hemoglobin concentration to significantly and positively associated with change in Pbto2 [0.10 kPa/(g/dL) 95% confidence interval 0.03-0.17, p = 0.003]. Improvement in Pbto2 was not associated with baseline hemoglobin concentration or low Pbto2 (<1 kPa). Fifty-six percent of patients experienced an increase in LPR. No significant relationship between change in LPR or transfusion on pHbt and change in hemoglobin could be demonstrated.
  
  
  CONCLUSIONS
  Transfusion of packed red blood cells acutely results in improved brain tissue oxygen without appreciable effect on cerebral metabolism.
  
  
  BACKGROUND
  ISRCTN89085577.
authors.affiliation: Department of Anaesthesia, University of Cambridge, Cambridge, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Zygun
authors.forename: Jurgens
authors.initials: J
authors.lastname: Nortje
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hutchinson
authors.forename: Ivan
authors.initials: I
authors.lastname: Timofeev
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
authors.forename: Arun K
authors.initials: AK
authors.lastname: Gupta
mesh_terms: D000328:Adult; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000378:metabolism* / Q000628:therapy*; D017707:Erythrocyte Transfusion; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D011446:Prospective Studies
chemical_list: D010100:Oxygen