Introduction: The use of cardiopulmonary bypass (CPB) is necessary during the repair of most congenital heart disease (CHD). The surface area of the CPB circuit and the volume of the filling prime are relatively large concerning the volume of neonatal and pediatric patients. Consequently, blood is often required to maintain an adequate hematocrit (HCT) level throughout the procedure.

Objective: To evaluate the effects of ultrafiltration (UF) of the blood prime from the cardiopulmonary bypass circuit in children undergoing surgical procedures to correct heart disease.

Methods: This is a prospective interventional study with convenience sampling of fifty-five children undergoing elective one of two groups as follows: control group (group 1) not using ultrafiltration of blood prime and experimental group (group 2) with UF of the prime before CPB. Blood samples were obtained for analysis of CPB circuit prime, during the intraoperative and after surgery in immediate postoperative period (IPO). The duration of mechanical ventilation (MV), intensive care unit (ICU) stay, and length of postoperative hospital stay were compared between the 2 groups.

Results: Levels of glucose, potassium and lactate values demonstrated a significant decrease after prime ultrafiltration in group 2, however an increase in sodium values was revealed (p= <0,001). In the present study, to postoperative clinical outcomes, there was not difference between groups in the duration of mechanical ventilation and ICU stay. However , length of postoperative hospital stay, group 1 demonstrated longer time in comparison with the group 2 [13 (6 – 35) vs 9 (6 – 34); Median (interquartile range) and p= 0.032]. Group 2 demonstrated lower lactate values in intraoperative and in the immediate postoperative period (p= 0.008). It was observed in the first postoperative 24 hours, stability in lactate levels between the groups.

Conclusion: Analysis of intraoperative and postoperative laboratory outcomes showed overall stability in blood parameters, with some specific variations in potassium and lactate levels. The observation of a shorter hospital stay in the group that had the prime ultrafiltration, it is suggested that this technique may help shorten the hospitalization period.