title: Effect of Hemoglobin Transfusion Threshold on Cerebral Hemodynamics and Oxygenation.
abstract: Cerebral dysfunction caused by traumatic brain injury may adversely affect cerebral hemodynamics and oxygenation leading to worse outcomes if oxygen capacity is decreased due to anemia. In a randomized clinical trial of 200 patients comparing transfusion thresholds <7 g/dl versus 10 g/dl, where transfusion of leukoreduced packed red blood cells was used to maintain the assigned hemoglobin threshold, no long-term neurological difference was detected. The current study examines secondary outcome measures of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain tissue oxygenation (PbtO2) in patients enrolled in this randomized clinical trial. We observed a lower hazard for death (hazard ratio [HR]=0.12, 95% confidence interval [CI]=0.02-0.99) during the first 3 days post-injury, and a higher hazard for death after three days (HR=2.55, 95% CI=1.00-6.53) in the 10 g/dl threshold group as compared to the 7 g/dL threshold group. No significant differences were observed for ICP and CPP but MAP was slightly lower in the 7 g/dL group, although the decreased MAP did not result in increased hypotension. Overall brain tissue hypoxia events were not significantly different in the two transfusion threshold groups. When the PbtO2 catheter was placed in normal brain, however, tissue hypoxia occurred in 25% of patients in the 7 g/dL threshold group, compared to 10.2% of patients in the 10 g/dL threshold group (p=0.04). Although we observed a few differences in hemodynamic outcomes between the transfusion threshold groups, none were of major clinical significance and did not affect long-term neurological outcome and mortality.
authors.affiliation: 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas.
authors.forename: Jose-Miguel
authors.initials: JM
authors.lastname: Yamal
authors.affiliation: 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas.
authors.forename: M Laura
authors.initials: ML
authors.lastname: Rubin
authors.affiliation: 2 Department of Basic Vision Sciences, College of Optometry and Texas Institute for Measurement Evaluation and Statistics, University of Houston , Houston, Texas.
authors.forename: Julia S
authors.initials: JS
authors.lastname: Benoit
authors.affiliation: 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Tilley
authors.affiliation: 3 Department of Neurosurgery, Baylor College of Medicine , Houston, Texas.
authors.forename: Shankar
authors.initials: S
authors.lastname: Gopinath
authors.affiliation: 4 Department of Psychology, University of Houston , Houston, Texas.
authors.forename: H Julia
authors.initials: HJ
authors.lastname: Hannay
authors.affiliation: 5 Department of Emergency Medicine and Internal Medicine, University of Texas Health Science Center at Houston , Houston, Texas.
authors.forename: Pratik
authors.initials: P
authors.lastname: Doshi
authors.affiliation: 6 Department of Emergency Medicine, Brigham and Women's Hospital , Boston, Massachusetts.
authors.forename: Imoigele P
authors.initials: IP
authors.lastname: Aisiku
authors.affiliation: 3 Department of Neurosurgery, Baylor College of Medicine , Houston, Texas.
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Robertson
mesh_terms: D001930:Brain Injuries / Q000378:metabolism / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D017707:Erythrocyte Transfusion / Q000379:methods* / Q000592:standards; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D017063:Outcome Assessment, Health Care; D010100:Oxygen / Q000378:metabolism*
chemical_list: D010100:Oxygen
keywords: blood flow; clinical trial; intracranial pressure; prospective study; traumatic brain injury