Retrograde Autologous Priming: Is It Really Effective in Reducing Red Blood Cell Transfusions during Extracorporeal Circulation?

Lim, Cheong; Son, Kuk Hui; Park, Kay Hyun; Jheon, Sanghoon; Sung, Sook Whan

Abstract

BACKGROUND: Retrograde autologous priming (RAP) is known to be useful in decreasing the need of transfusions in cardiac surgery because it prevents excessive hemodilution due to the crystalloid priming of cardiopulmonary bypass circuit. However, there are also negative side effects in terms of blood conservation. We analyzed the intraoperative blood-conserving effect of RAP and also investigated the efficacy of autotransfusion and ultrafiltration as a supplemental method for RAP. MATERIAL AND METHOD: From January 2005 to December 2007, 117 patients who underwent isolated coronary artery bypass operations using cardiopulmonary bypass (CPB) were enrolled. Mean age was 63.9+/-9.1 years (range 36~83 years) and 34 patients were female. There were 62 patients in the RAP group and 55 patients in he control group. Intraoperative autotransfusion was performed via the arterial line. RAP was done just before initiating CPB using retrograde drainage of the crystalloid priming solution. Both conventional (CUF) and modified (MUF) ultrafiltrations were done during and after CPB, respectively. The transfusion threshold was less than 20% in hematocrit. RESULT: Autotransfusions were done in 79 patients (67.5%) and the average amount was 142.5+/-65.4 mL (range 30~320 mL). Homologous red blood cell (RBC) transfusion was done in 47 patients (40.2%) and mean amount of transfused RBC was 404.3+/-222.6 mL. Risk factors for transfusions were body surface area (OR 0.01, 95% CI 0.00~0.63, p=0.030) and cardiopulmonary bypass time (OR 1.04, 95% CI 1.01~1.08, p=0.019). RAP was not effective in terms of the rate of transfusion (34.5% vs 45.2%, p=0.24). However, the amount of transfused RBC was significantly decreased (526.3+/-242.3ml vs 321.4.+/-166.3 mL, p=0.001). Autotransfusion and ultrafiltration revealed additive and cumulative effects in decreasing transfusion amount (one; 600.0+/-231.0 mL, two; 533.3+/-264.6 mL, three; 346.7+/-176.7 mL, four; 300.0+/-146.1 mL, p=0.002).
CONCLUSION
Even though RAP did not appear to be effective in terms of the number of patients receiving intraoperative RBC transfusions, it could conserve blood in terms of the amount transfused and with the additive effects of autotransfusion and ultrafiltration. If we want to maximize the blood conserving effect of RAP, more aggressive control will be necessary - such as high threshold of transfusion trigger or strict regulation of crystalloid infusion, and so forth.