A random selection of 484 patients who underwent surgery in the 6 months prior to the introduction of RAP was used as a historical control group. This control group (SP) received a standard CPB circuit and priming method (1.91 ± 0.23 L). The RAP group (n=211) received the same standard CPB circuit, but with a crystalloid prime of 1.45L (± 0.20 L), and 400mL of autologous blood. The autologous blood was obtained by passive retrograde flow into the reservoir via the aortic cannula immediately prior to bypass to complete the circuit prime.
The crystalloid prime volume of the CPB circuit for the RAP group (1.45± 0.20 L) was significantly lower than the SP group (1.91 ± 0.26 L) (p>0.001). During CPB haemoglobin measured 10 minutes after the onset of CPB dropped by 28.71% in the control group compared to pre-CPB and by 26.81% in the RAP study group (p=0.031). The net fluid additions during CPB for the SP group was 2.39 ± 0.98 L compared to 1.45 ± 0.96 L for the RAP group (p>0.001). In the SP group, 20.5% of patients received a blood transfusion, compared to only 9.43% in RAP group (p >0.02). No complications relating to RAP were reported.
The significant reduction in prime volume within the RAP group, coupled with lower net crystalloid additions has led to a significant decline in banked-RBC transfusions. RAP appears to be a safe and cost effective means of reducing the number of patients requiring RBC transfusions during cardiac operations.
The authors would like to acknowledge the support of all the staff at Cambridge Perfusion Services as well as the surgical and anaesthetic staff, in particular Dr. Sunit Ghosh, at Papworth Hospital NHS Trust.
1 Rosengart, T.K. DeBois, W. O’Hara, M. Helm, R. Gomez, M. Altorki, N. Ko, W. Hartman, G.S. Isom, O.W. and Krieger, K.H. Retrograde autologous priming for cardiopulmonary bypass: a safe and effective means of decreasing haemodilution and transfusion requirements 1998; Journal of Thoracic Cardiovascular Surgery. 115: 426-438.
2 Zelinka, E.S. Ryan, P. McDonald, J. and Larson J. Retrograde autologous prime with shortened bypass circuits in high-risk coronary artery surgery patients 2004; Journal of Extracorporeal Technology. 36: 343-347.
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