title: Hemodilution and surgical hemostasis contribute significantly to transfusion requirements in patients undergoing coronary artery bypass.
abstract: OBJECTIVE
  We sought to determine the incidence of and risk factors for the development of low intraoperative hematocrit levels and of excessive postoperative bleeding in patients undergoing coronary artery bypass grafting, whether the risk factors are the same, and their effect on blood product transfusions.
  
  
  METHODS
  We performed a prospective cohort study of 613 adult patients who underwent coronary artery bypass grafting in 3 tertiary, university-affiliated hospitals during the period from October 1, 2000, to March 31, 2001.
  
  
  RESULTS
  Low intraoperative hematocrit levels (<19%) were found in 131 (24%) patients who had operations performed with extracorporeal circulation compared with in 3 (4%) patients with operations performed off pump. In multivariate analysis this was associated with older age, female sex, lower preoperative hemoglobin levels, lower body surface area, longer duration on bypass, and use of higher total volumes with more hydroxyethyl starch in the circuit. Low intraoperative hematocrit levels did not predict excessive postoperative hemorrhage (>1 L of mediastinal drainage in the first 12 hours). This occurred in 26% (n = 140) of patients undergoing on-pump operations and in 25% of patients undergoing off-pump operations and in multivariate analysis was associated with male sex, longer pump times, not receiving aprotinin, and operations performed by certain surgeons but not with total circuit or hydroxyethyl starch volume.
  
  
  CONCLUSIONS
  We observed that the risk factors for the development of a low intraoperative hematocrit level and excessive postoperative bleeding differed. Our results suggest that decreasing these outcomes in patients undergoing cardiac surgery requires a comprehensive approach, including limiting hemodilution, particularly in female subjects with lower preoperative hemoglobin levels, and careful attention to surgical hemostasis.
authors.affiliation: Department of Critical Care, SMBD Jewish General Hospital, McGill University, Montreal, Quebec, Canada. sandra.dial@mcgill.ca
authors.forename: Sandra
authors.initials: S
authors.lastname: Dial
authors.forename: Eugene
authors.initials: E
authors.lastname: Delabays
authors.forename: Martin
authors.initials: M
authors.lastname: Albert
authors.forename: Anne
authors.initials: A
authors.lastname: Gonzalez
authors.forename: Jordan
authors.initials: J
authors.lastname: Camarda
authors.forename: Adora
authors.initials: A
authors.lastname: Law
authors.forename: Dick
authors.initials: D
authors.lastname: Menzies
mesh_terms: D000368:Aged; D000740:Anemia / Q000209:etiology; D007611:Aprotinin / Q000008:administration & dosage; D016063:Blood Loss, Surgical; D001803:Blood Transfusion; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D047549:Coronary Artery Bypass, Off-Pump; D005260:Female; D006400:Hematocrit; D006438:Hemodilution / Q000009:adverse effects; D006488:Hemostasis, Surgical / Q000009:adverse effects; D006490:Hemostatics / Q000008:administration & dosage; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D010952:Plasma Substitutes / Q000008:administration & dosage; D011183:Postoperative Complications; D019106:Postoperative Hemorrhage
chemical_list: D006490:Hemostatics; D010952:Plasma Substitutes; D007611:Aprotinin