title: Advance targeted transfusion in anemic cardiac surgical patients for kidney protection: an unblinded randomized pilot clinical trial.
abstract: BACKGROUND
  : Acute kidney injury (AKI) is a serious complication of cardiac surgery, and preoperative anemia and perioperative erythrocyte transfusion are important risk factors. Prophylactic erythrocyte transfusion in anemic patients may, therefore, protect against AKI.
  
  
  METHODS
  : In this unblinded, parallel-group, randomized pilot trial, 60 anemic patients (hemoglobin 10-12 g/dL) undergoing cardiac surgery with cardiopulmonary bypass were randomized (1:1) to prophylactic transfusion (2 units of erythrocytes transfused 1 to 2 days before surgery (n = 29) or standard of care (transfusions as indicated; n = 31). Between-group differences in severity of perioperative anemia, transfusion, and AKI (more than 25% drop in estimated glomerular filtration rate) were measured. The relationships between transfusion, iron levels, and AKI were also measured.
  
  
  RESULTS
  : Perioperative anemia and erythrocyte transfusions were lower in the prophylactic transfusion group--median (25th, 75th percentiles) for nadir hemoglobin was 8.3 (7.9, 9.1) versus 7.6 (6.9, 8.2) g/dL (P = 0.0008) and for transfusion was 0 (0, 2) versus 2 (1, 4) units (P = 0.0002)--but between-group AKI rates were comparable (11 patients per group). In 35 patients with iron studies, perioperative transfusions were directly related to postoperative transferrin saturation (correlation coefficient 0.6; P = 0.0002), and high (more than 80%) transferrin saturation was associated with AKI (5/5 vs. 8/30; P = 0.005), implicating transfusion-related iron overload as a cause of AKI.
  
  
  CONCLUSIONS
  : In anemic patients, prophylactic erythrocyte transfusion reduces perioperative anemia and erythrocyte transfusions, and may reduce plasma iron levels. Adequately powered studies assessing the effect of this intervention on AKI are warranted.
authors.affiliation: Department of Anesthesia and Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada. keyvan.karkouti@uhn.ca
authors.forename: Keyvan
authors.initials: K
authors.lastname: Karkouti
authors.forename: Duminda N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: Terrence M
authors.initials: TM
authors.lastname: Yau
authors.forename: Stuart A
authors.initials: SA
authors.lastname: McCluskey
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chan
authors.forename: Pui-Yuen
authors.initials: PY
authors.lastname: Wong
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
authors.forename: Siroos
authors.initials: S
authors.lastname: Hozhabri
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology* / Q000517:prevention & control*; D000368:Aged; D000740:Anemia / Q000150:complications* / Q000628:therapy*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D017707:Erythrocyte Transfusion / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013997:Time Factors