Retrograde autologous priming: is it useful in elective on-pump coronary artery bypass surgery?

Background The effect of reduced cardiopulmonary bypass (CPB) prime volume by retrograde autologous priming (RAP) was studied. Methods Twenty patients undergoing elective coronary artery bypass grafting were randomized to either standard prime (SP) volume (1,602 ± 202 mL crystalloid prime, N = 10) or RAP (395 ± 150 mL). RAP was performed by draining crystalloid prime from the arterial and venous lines into a recirculation bag before CPB. Cardiac index, pulmonary vascular resistance index, systemic vascular resistance index, alveolar-arterial oxygen tension difference, pulmonary shunt fraction, extravascular lung water (EVLW), plasma colloid osmotic pressure (COP), crystalloid fluid balance, body weight, and clinical parameters were evaluated perioperatively. Results Demographic data and operative parameters were equal for patients in both groups. During CPB, COP was reduced by 55% in the SP group (9.8 ± 2.0 vs 21.4 ± 2.1 mm Hg) and by 41% in the RAP group (12.4 ± 1.1 vs 20.9 ± 1.8 mm Hg) (p = 0.008, SP vs RAP group). Compared with preoperatively, EVLW was unchanged in the RAP group 2 hours post-CPB, but it was elevated by 21% in the SP group (p = 0.002, SP vs RAP group). End-CPB crystalloid fluid balance was significantly reduced in the RAP group (1,857 ± 521 vs 2,831 ± 637 mL). Postoperative (day 2) weight gain in the SP group (1.5 ± 1.2 kg, p = 0.021) was absent in the RAP group (0.1 ± 0.9, NS). Postoperative time to full mobilization was shorter in the RAP group. Postpump cardio-respiratory function did not differ among groups. Conclusions This small-scale pilot study indicates that by reducing crystalloid fluid administration and fall of COP during CPB, RAP reduces postpump EVLW accumulation and weight gain in uncomplicated coronary artery bypass graft patients with no associated effects on cardio-respiratory function.