Are any biocompatible coatings capable of attenuating the deleterious effects of cardiopulmonary bypass?

BACKGROUND

Biocompatible circuits (BCC) are intended to decrease the activation of blood to the artificial cardiopulmonary bypass (CPB) surface. Typically, the coatings are made of various inert substances or molecules physiologically similar to endothelium. Thromboelastography (TEG) graphically represents clot formation, strength of clotting and fibrinolysis. TEG analysis was undertaken to determine if coagulation could be preserved by the BCC.

METHODS

Five different BCC were studied in clinical applications. These five coated circuits were then compared to an identical circuit where only the oxygenator was coated. A pre- and post-bypass TEG was done for comparison. Six well-studied parameters of TEG analysis were compared: R time, angle, K, maximum amplitude (MA), LY30% and Clot Index (CI). Postoperative bleeding and transfusion requirements were compared to TEG results for comparison.

RESULTS

All postoperative TEG results were significantly different from preoperative parameters except LY30%. No BCC circuit was able to prevent the significant disruption of the observed TEG coagulation parameters R, K, angle, MA and CI. Of note, the postoperative TEG parameters resulting from the Control and Trillium groups--which had the same type of oxygenator - were practically identical. The oxygenator, which represents the largest surface area in the CPB circuit, is the single most important factor influencing coagulation.

CONCLUSION

While not harmful, BCC are ineffective in preserving TEG coagulation parameters post CPB. Clinical findings support laboratory TEG results in that there were no differences in bleeding or transfusion requirements between groups.