Is it true that cardiac operations with cardiopulmonary bypass impair the reticuloendothelial system?

Reticuloendothelial system (RES) function after cardiac operations is a controversial issue. Sequential changes in plasma fibronectin levels and RES phagocytic function were studied after a cardiac operation and a lung operation (control). In the cardiac operation group, the plasma fibronectin level decreased until the third postoperative day and increased thereafter. Reticuloendothelial system phagocytic function remained unchanged on the third postoperative day and then it increased. However, in the control group it increased significantly after operation. In the past, investigators have demonstrated a decline in plasma fibronectin levels following cardiac operation and have assumed that RES function was impaired. However, this sequential study showed that phagocytic function was not impaired, but its enhanced phase was delayed. Moreover, our previous morphologic studies demonstrated that RES function was potentially activated after cardiopulmonary bypass. It appears that the delay of the enhanced phase is caused by the overloading of substances which must be processed by the RES during cardiopulmonary bypass. Thus, we conclude that cardiac operation produces hyperactive, yet oversaturated RES function. There is no impairment of RES function after cardiac operations.