Background and objective: Extreme haemodilution occurring with cardiopulmonary bypass imposes a primary risk factor for blood transfusion in small adult cardiac surgical patients. Priming of the cardiopulmonary bypass circuit with patients' own blood [retrograde autologous priming (RAP)] is a technique used to limit haemodilution and reduce transfusion requirements. We designed this study to evaluate the effects of RAP on reducing perioperative blood transfusion in small adults.
Methods: One hundred and twenty patients with a body surface area of less than 1.5 m undergoing first-time, nonemergency cardiac surgery were randomized to either the standard priming group or the RAP group. All patients followed strict transfusion criteria. Homologous transfusion, haematocrit, plasma colloid osmotic pressure and postoperative clinical outcomes were evaluated perioperatively.
Results: Patient characteristics and operative parameters were equal for patients in both groups. With autologous priming, a mean volume of 614.8 +/- 138.8 ml of priming solution was replaced with autologous blood. This allowed a significantly higher haematocrit value during cardiopulmonary bypass (P < 0.05). Red blood cell transfusion was necessary in 83.3% of patients of the standard priming group on pump, whereas only 26.7% of patients of the RAP group required transfusion (P < 0.01). The overall transfusion rate of the RAP group was significantly less than that in the standard priming group during the hospitalization (90.0 vs. 50.0%, P < 0.01). Amongst patients who received transfusion on pump, the number of homologous units of packed red blood cells was less in the RAP group than that in the standard priming group intraoperatively and perioperatively (0.94 +/- 0.32 vs. 1.48 +/- 0.68 units, P = 0.03; 1.24 +/- 0.54 vs. 1.69 +/- 0.69 units, P = 0.15). Ten minutes after aortic cross-clamp, colloid osmotic pressure was reduced by 39.7 +/- 2.8% in the standard priming group and by 28.6 +/- 3.2% in the RAP group (P < 0.05). Clinical outcomes were similar with respect to pulmonary, renal and hepatic function, length of ICU stay and hospital stay.
Conclusion: RAP resulted in a significant decrease in intraoperative haemodilution and conserved the use of blood. This technique should be considered for patients with a small body surface area (<1.5 m) undergoing open heart surgery.