[In vitro and clinical study of complement activation during cardiopulmonary bypass with reference to types of...

Complement activation during cardiopulmonary bypass (CPB) was studied in vitro and in vivo with regard to types of oxygenator, primed autologous blood and patient's factor. In vitro study was performed using human blood in a simple circuit involving an oxygenator, roller pump and connector tubing. In vivo study was carried out in 118 patients and divided into bubble (BO) and membrane oxygenator (MO) groups. The influence of primed homologous to circulating autologous blood volume (H/A) ratio was also examined. In vitro study, C3a and C4a increased steeply in the BO group. On the other hand, in the MO group, C3a and C4a increased up to minute of 60, and afterwards gradually decreased. In clinical study, complement was more activated in the BO group than in the MO group. These results supported that in the BO group, immunoglobulin denatured by blood-gas interface played an important role in complement activation. In membrane oxygenator, blood-material interface was a major cause of complement activation. In order to reduce these complement activation, we introduced fresh concentrated red cells, which was almost free of immunoglobulin, as a primed blood. Application of this method in clinical study, complement activation was reduced and postoperative lung function was improved significantly. These changes were more significant in the BO group. In the high H/A group, differences of anaphylatoxin level between BO and MO group had a tendency to increase. This method is useful to the CPB case of neonate and infant, which was subjected to be primed with a large amount of blood.