Background:

Allogenic blood product transfusion has well-documented risks and adverse outcomes. To limit perioperative transfusions for neonates and infants undergoing cardiac surgery, our institution launched a blood conservation program in May, 2021. Over the past several years, our standard has changed from blood priming the cardiopulmonary bypass (CPB) circuit for most patients ≤12 kilograms (kg) to administering an asanguinous prime to all patients with an adequate baseline hematocrit (HCT), regardless of weight. For those requiring transfusion, the technique of modified blood priming (MBP), introduced herein, presents an intermediate solution between a clear and standard blood prime, with the goal of administering the minimum amount of packed red blood cells (PRBC) to maintain safe oxygen-carrying capacity while on CPB.

Methods:

The crystalloid prime in the core of the CPB circuit (venous reservoir, arterial pump boot, and oxygenator) is displaced with a pre-calculated amount of PRBC to maintain an on-bypass HCT of ≥24%. In addition, the crystalloid in the arterial and venous lines is replaced with patient blood volume via retrograde and venous autologous priming (RAP and VAP). Once CPB is established, the remaining crystalloid in the ultrafiltration (UF) and cardioplegia (CPG) circuits is displaced into a syringe with circulating blood to minimize any further hemodilution.

Results:

We have applied MBP to 26 patients weighing less than 7 kg. The mean amount of PRBC these patients received during CPB, including in the prime, was half the amount when compared to the initial amount of PRBC we include in our institution’s standard blood prime alone.

Conclusion:

The MBP technique allows safe initiation of CPB in the subset of neonates and infants with a post-dilutional hematocrit (PDHCT) calculated at less than 24% while avoiding excessive transfusion of exogenous blood products.