title: Intraoperative hemoglobin levels and transfusion independently predict stroke after cardiac operations.
abstract: BACKGROUND
  Anemia has been associated with adverse cerebrovascular outcomes, particularly after cardiac operations. This study was conducted to determine if hemoglobin levels during and after cardiopulmonary bypass (CPB) predict postoperative stroke in cardiac surgical patients, independent of transfusion requirements.
  
  
  METHODS
  Individuals who had sustained a clinical postoperative stroke (cases) were matched 1:2 with controls by age, sex, surgical procedure, and year of operation. In 617 patients, conditional logistic regression was performed to analyze associations between hemoglobin levels before and after CPB, and stroke.
  
  
  RESULTS
  After adjustment for potentially confounding vascular risk factors, lower hemoglobin after CPB was associated with a higher risk of stroke, even after adjustment for the amount of packed red blood cells transfused (adjusted odds ratio, 1.28; 95% confidence interval, 1.00 to 1.64, per point of lower hemoglobin level; adjusted odds ratio for stroke per higher quartile of packed red blood cells transfused in this model, 1.37; 95% confidence interval, 1.02 to 1.83). Similar associations were not found for hemoglobin concentrations preoperatively nor change in hemoglobin from before to after CPB. A post-CPB hemoglobin level below the median was associated with 37% increased odds of a postoperative stroke occurring (p = 0.02).
  
  
  CONCLUSIONS
  Lower postoperative hemoglobin levels and higher intraoperative transfusion requirements are each independently associated with a higher risk of stroke. Reduced cerebral oxygen delivery due to anemia may contribute to cerebral injury after coronary artery bypass grafting.
authors: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
authors: Zainab S
authors: ZS
authors: Bahrainwala
authors: Maura A
authors: MA
authors: Grega
authors: Charles W
authors: CW
authors: Hogue
authors: William A
authors: WA
authors: Baumgartner
authors: Ola A
authors: OA
authors: Selnes
authors: Guy M
authors: GM
authors: McKhann
authors: Rebecca F
authors: RF
authors: Gottesman
mesh_terms: D001803:Blood Transfusion / Q000706:statistics & numerical data; D002315:Cardiopulmonary Bypass; D016022:Case-Control Studies; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000453:epidemiology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D020521:Stroke / Q000453:epidemiology*
chemical_list: D006454:Hemoglobins