Effects of Mini-Volume Priming During Cardiopulmonary Bypass on Clinical Outcomes in Low-Bodyweight Neonates: Less Transfusion and Postoperative Extracorporeal Membrane Oxygenation Support.

Mixing of autologous blood with priming volume has relatively significant effects on blood composition, especially in low-bodyweight neonates. In an effort to reduce these effects, mini-volume priming (MP) has been applied in cardiopulmonary bypass (CPB). The present study was designed to examine the effect of MP on clinical outcomes of low-bodyweight neonates undergoing open heart surgery.We retrospectively reviewed medical records of low-bodyweight (2.5 kg or less) neonates who underwent open heart surgery in our center from January 2000 to December 2014. A total of 64 patients were included. MP was introduced in 2007, and became a routine protocol in 2009. Preoperative and intraoperative characteristics included age, bodyweight, RACHS-1, priming volume, CPB time, and aortic cross-clamp time, transfusion, and hematocrit during CPB. Clinical outcomes included 30-day mortality, postoperative extracorporeal membrane oxygenation (ECMO) support, open sternum status, prolonged mechanical ventilation care (>7 days), and acute renal failure. MP was utilized in 39 patients and conventional priming (CP) was used in 25 patients. The priming volume decreased to 126.0 mL in the MP group compared with 321.6 mL in the CP group. Transfusion volume during CPB was 87.3 mL in the MP group versus 226.8 mL in the CP group, and the difference was statistically significant (P < 0.001). Hematocrit at the end of the CPB and maximal decrease of hematocrit during CPB were not significantly different between the two groups. The 30-day mortality rate was 12.8% in the MP group versus 20.0% in the CP group. Postoperative ECMO support was performed in 5.1% of patients in the MP group versus 17.4% of patients in the CP group. Open sternum status was required in 20.8% of patients in the MP group versus 10.3% of patients in the CP group, and prolonged ventilator care was required in 54.2% of patients in the MP group versus 38.5% of patients in the CP group. However, no statistical significance was measured in any of the clinical outcome measures. Larger priming volume and higher RACHS-1 were significant risk factors of postoperative ECMO support in univariate and multivariate analysis. The results of the present study suggest that MP may be beneficial in avoiding transfusion without having a significant effect on the hematocrit. Clinical outcomes did not differ between the two groups. However, larger priming volume was a significant risk factor for postoperative ECMO support with RACHS-1 category.