Which is the optimal option during pediatric cardiopulmonary bypass: high colloid oncotic pressure priming, ultrafiltration or both?

Colloid oncotic pressure, Pediatric, Cardiopulmonary bypass, Ultrafiltration

We read with great interest the recent article by Dr Golab and colleagues regarding the relevance of colloid oncotic pressure (COP) during neonatal and infant cardiopulmonary bypass (CPB) [1]. This prospective randomized study is a good attempt to propose a reasonable and effective level of COP during CPB in small babies.

COP has been regarded as an important index during CPB in neonates and infants, which is closely related to the avoidance of tissue edema and the functional recovery of major organs after CPB [2]. The level of COP in healthy adults is approximately 20–25 mmHg, but the normal COP range in newborns and infants remains controversial [3]. Therefore, the management of COP during CPB in neonates and infants will greatly differ from that in adults. It is well known that priming with fresh-frozen plasma (FFP), albumin, and other colloid solutions has been used to improve COP during CPB. The development and use of ultrafiltration techniques, however, have enabled an increasing number of patients to maintain satisfactory COP levels without the excessive use of blood products.

We would like to make several comments concerning this clinical investigation of COP levels during pediatric CPB:

1. Some studies have demonstrated that the physical COP range in newborns and infants is different from adults [4]. This is because these babies suffered from a variety of congenital heart abnormities. Dr Golab and his colleagues monitored the levels of pre-CPB COP, which were similar in two groups, but did not show the differences in COP between cyanotic and acyanotic diseases. It would be best to choose the same kind of diseases in the same COP level group because different COP levels were usually maintained during CPB, according to the different cyanotic degree or hematocrit levels.

2. In this clinical study, the standard COP group maintained COP >15 mmHg during CPB. In the high COP group, COP was maintained above 18 mmHg. Although all cases were divided into a lower and a higher COP group, the differences in COP between these two groups were too small. Practically, it is difficult to control the expected COP level during CPB within these small differences in two groups.

3. Ultrafiltration has been widely accepted in CPB, especially in neonates and infants. Not only can it increase the hematocrit and COP levels perioperatively, but it also improves the recovery of postoperative respiratory function by decreasing the overload of volume and the level of inflammation mediums [5]. Dr Golab and colleagues did not use ultrafiltration in their clinical protocol. They maintained the higher COP by adding albumin during CPB, but our concern is how to increase the hematocrit level at the end of CPB, if more crystalloid solution was transfused into the circuit, and how to control the overload of volume if the urine is insufficient. Therefore, we are not sure if this method is available to infants during CPB without ultrafiltration.