title: The association of hemodilution and transfusion of red blood cells with biochemical markers of splanchnic and renal injury during cardiopulmonary bypass.
abstract: BACKGROUND
  Hemodilution is the main cause of a low hematocrit concentration during cardiopulmonary bypass. This low hematocrit may be insufficient for optimal tissue oxygen delivery and often results in packed cell transfusion. Our objective in this study was to find a relationship between intraoperative hematocrit and allogeneic blood transfusion on release of postoperative injury markers from the kidneys and the splanchnic area.
  
  
  METHODS
  Fifty consecutive patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were included. Systemic tissue hypoxia was assessed by lactate concentrations. Kidney and splanchnic ischemia were assessed by the measurement of N-acetyl-beta-D-glucosaminidase (NAG) and intestinal fatty acid binding protein (IFABP) in urine. Patients were retrospectively placed into groups according to their lowest hematocrit concentration on bypass (<24% or >or=24%).
  
  
  RESULTS
  The intraoperative lactate and the postoperative NAG and IFABP concentrations were higher in the low hematocrit group (<24%) than in the high hematocrit group (>or=24%; P < 0.05). Low hematocrit correlated with higher lactate concentrations (R(2) = 0.150, P < 0.01) and with higher NAG concentrations (R(2) = 0.138, P < 0.01) and IFABP concentrations (R(2) = 0.107, P < 0.01) postoperatively. Transfusion of packed cells during cardiopulmonary bypass correlated with higher lactate (R(2) = 0.089, P < 0.05), NAG (R(2) = 0.431, P < 0.01), and IFABP concentrations (R(2) = 0.189, P < 0.01).
  
  
  CONCLUSIONS
  The results support the concept that hemodilution below an intraoperative hematocrit of 24% and consequently transfusion of red blood cells is related to release of injury markers of the kidneys and splanchnic area.
authors.affiliation: epartments of *Cardiac Surgery, University Hospital Vrije Universiteit,Amsterdam.
authors.forename: Rien A J M
authors.initials: RA
authors.lastname: Huybregts
authors.forename: Roel
authors.initials: R
authors.lastname: de Vroege
authors.forename: Evert K
authors.initials: EK
authors.lastname: Jansen
authors.forename: Anne W
authors.initials: AW
authors.lastname: van Schijndel
authors.forename: Herman M T
authors.initials: HM
authors.lastname: Christiaans
authors.forename: Willem
authors.initials: W
authors.lastname: van Oeveren
mesh_terms: D000118:Acetylglucosaminidase / Q000097:blood; D000368:Aged; D015415:Biomarkers; D001784:Blood Gas Analysis; D002315:Cardiopulmonary Bypass; D003401:Creatine / Q000097:blood; D017707:Erythrocyte Transfusion / Q000009:adverse effects*; D050556:Fatty Acid-Binding Proteins / Q000097:blood; D005260:Female; D006400:Hematocrit; D006438:Hemodilution / Q000009:adverse effects*; D006801:Humans; D007036:Hypothermia, Induced; D007511:Ischemia / Q000378:metabolism; D007674:Kidney Diseases / Q000209:etiology* / Q000378:metabolism*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000378:metabolism*; D013152:Splanchnic Circulation / Q000502:physiology*
chemical_list: D015415:Biomarkers; D050556:Fatty Acid-Binding Proteins; D019344:Lactic Acid; D000118:Acetylglucosaminidase; D003401:Creatine