Hemostasis and the Effect of Cardiopulmonary Bypass on Hemostasis

Hemostasis is a dynamic ongoing physiologic process. The body reacts to vascular injury by local vasoconstriction and the activation of a barrage of cellular and biochemical mediators/activators to repair the injury. Concurrently opposing mediators/inhibitors are activated to locally limit the repair process, thus protecting the essential fluidity of the circulation. The call to clot is always accompanied by the message to temper the action. During the seemingly quiescent phases, the hemostatic system is actively maintaining the blood in a fluid state. It is the perturbation of this intricate “homeostatic” hemostasis during cardiac surgery by synthetic or foreign nonvascular surfaces, exogenous pharmaceuticals, endogenous biochemical mediators, and surgical steel that results in post-bypass coagulopathy.