Effect of a miniaturized cardiopulmonary bypass system on the inflammatory response and cardiac function in neonatal piglets

The cognitive impairment and hemodynamic instability after neonatal cardiac surgery with cardiopulmonary bypass (CPB) might be exacerbated by hemodilution. Therefore, this study investigated the impact of different bloodless prime volumes on the hemodynamics and the inflammatory response by a miniaturized CPB system in neonatal piglets. The bypass circuit consisted of a Capiox RX05 (Capiox Baby RX, Terumo Corp., Tokyo, Japan) oxygenator and 3/16 internal diameter arterial and venous polyvinyl chloride tubing lines, with a minimum 75 mL prime volume. Twelve 1-week-old piglets were placed on a mild hypothermic CPB (32°C) at 120 mL/kg/min for 2 h. The animals were divided into two groups, based on the volume of the prime solution. The priming volume was 75 mL in Group I and 175 mL in Group II. No blood transfusions were performed, and no inotropic or vasoactive drugs were used. The interleukin-6 (IL-6) and thrombin-antithrombin (TAT) complex levels, as well as right ventricular and pulmonary functions, were measured before and after CPB. Group I had low levels of IL-6 and TAT immediately after CPB (4370 ± 2346 vs. 9058 ± 2307 pg/mL, P < 0.01 and 9.9 ± 7.7 vs. 25.1 ± 8.8 ng/mL, P < 0.01, respectively). Group I had significantly improved cardiopulmonary function, cardiac index (0.22 ± 0.03 vs. 0.11 ± 0.05 L/kg/min, P < 0.001), and pulmonary vascular resistance index (7366 ± 2860 vs. 28 620 ± 15 552 dynes/cm⁵/kg, P < 0.01) compared with Group II. The miniaturized bloodless prime circuit for neonatal CPB demonstrated that the influence of hemodilution can reduce the subsequent inflammatory response. In addition, a low prime volume could therefore be particularly effective for attenuating pulmonary vascular resistance and right ventricular dysfunction in neonates.