title: The effect of retrograde autologous priming volume on haemodilution and transfusion requirements during cardiac surgery.
abstract: OBJECTIVE
  Many cardiac procedures using cardiopulmonary bypass (CPB) still require intraoperative transfusion. Retrograde autologous priming (RAP) has been introduced to decrease haemodilution and the blood transfusion rate. This study is designed to determine the influence or RAP on intraoperative haematocrit, transfusion and its clinical consequences.
  
  
  METHODS
  The RAP effect was retrospectively studied in 753 patients during contemporary cardiac surgery, targeting a haematocrit of 25%. Multivariate linear regression analysis was performed to identify the independent factors influencing intraoperative haematocrit, transfusion rate and transfusion quantity.
  
  
  RESULTS
  RAP was used in 498 patients and compared with 255 controls. RAP decreased the haemodilution level (nadir haematocrit 26.8 standard deviation [SD] 4.0% in RAP vs 25.8 SD 3.6% in controls; P = 0.001) and transfusion frequency (26.1 vs 33.3%, P = 0.04), despite smaller patients (body surface area [BSA] 1.86 SD 0.20 m(2) vs 1.91 SD 0.21 m(2) in RAP vs controls; P = 0.002) with lower preoperative haematocrit (38.9 SD 4.4% vs 40.5 SD 4.6%; P < 0.001). Optimal RAP volume was overall 475 ml (ROC area 0.55; 95% confidence interval [CI] 0.50-0.60; P = 0.04) and 375 ml in patients with BSA <1.7 m(2) (ROC area 0.63; 95% CI 0.54-0.73; P = 0.008) to decrease the transfusion incidence. Multivariate analysis revealed RAP volume as a significant determinant of nadir haematocrit (β = 0.003, 95% CI 0.002-0.004, P < 0.001) and transfusion rate (odds ratio (OR) = 0.997, 95% CI 0.996-0.999, P < 0.001), independent of BSA, gender and preoperative haematocrit.
  
  
  CONCLUSIONS
  Retrograde autologous priming is an effective adjunct to decrease the blood transfusion rate, coping with the CPB-related haemodilution and its adverse clinical effects. A RAP volume individualized to each patient offers most benefit as part of a multidisciplinary blood conservation approach.
authors.affiliation: Department of Perfusion, Heart Centre, University Hospital of Ghent, Ghent, Belgium. korneel.vandewiele@ugent.be
authors.forename: Korneel
authors.initials: K
authors.lastname: Vandewiele
authors.forename: Thierry
authors.initials: T
authors.lastname: Bové
authors.forename: Filip M J J
authors.initials: FM
authors.lastname: De Somer
authors.forename: Daniël
authors.initials: D
authors.lastname: Dujardin
authors.forename: Martin
authors.initials: M
authors.lastname: Vanackere
authors.forename: Dirk
authors.initials: D
authors.lastname: De Smet
authors.forename: Annelies T
authors.initials: AT
authors.lastname: Moerman
authors.forename: Stefaan
authors.initials: S
authors.lastname: Bouchez
authors.forename: Katrien
authors.initials: K
authors.lastname: François
mesh_terms: D000368:Aged; D019540:Area Under Curve; D001804:Blood Transfusion, Autologous / Q000009:adverse effects; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002315:Cardiopulmonary Bypass; D016009:Chi-Square Distribution; D005260:Female; D006400:Hematocrit; D006438:Hemodilution / Q000009:adverse effects; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
keywords: Blood transfusion; CPB components; Cardiopulmonary bypass; Retrograde autologous priming