Multifactorial comparison of modified and conventional perfusion strategies in a porcine model of cardiopulmonary bypass.

Background: Utilization of thromboresistant circuits in cardiopulmonary bypass (CPB) surgery has been controversial. However, due to the advantages associated with these types of circuits, we sought to evaluate the efficacy of use of low-dose heparin in conjunction with thromboresistant surfaces, closed perfusion system, elimination of blood-gas interface, maintenance of hematocrit to >25%, and systemic normothermia, with respect to the conventional strategy of non-thromboresistant open circuits with high-dose heparin, during 3 h of CPB in an animal model.

Methods: Using an open-chest swine model, animals were placed on CPB for 3 h with additional monitoring for 1 h post-CPB. Pigs were randomized into either a heparin-bonded circuit (HBC) group (n = 10) or a non-HBC (NHB) group (n = 10). Hemodynamic, hematologic, and biochemical parameters and multiphoton microscopy were used to compare the two groups.

Results: Pigs in the HBC group showed a 38.4% reduction in post-CPB blood loss in comparison with the NHB group (P = 0.0007). Additionally, compared with the HBC group, the NHB group exhibited a 32.7% post-CPB reduction in platelets (P < 0.001) and significant increases in alkaline phosphatase, aspartate aminotransferase, and creatine phosphokinase enzymes (P < 0.0202, P = 0.0015, P < 0.0001; respectively). Multiphoton imaging of the arterial filters revealed no entrapment of RBC, WBC, and platelets in the HBC group, while the filters in the NHB group were clogged by these cells.

Conclusion: Utilization of modified perfusion strategy employing low-dose heparin and closed thromboresistant circuits is successful in ameliorating the potential adverse hematologic and pro-inflammatory elements induced with open perfusion system of non-thromboresistant circuits most commonly used in cardiac surgery.