Blood and coagulation
Hemostasis is a critical homeostatic mechanism of survival that involves vascular, cellular, and plasma components that interact to stop bleeding. Vascular effects include vasoconstriction, expression of procoagulant factors such as tissue factor, and loss of normal anticoagulant functions of the endothelium. Coagulation and clot formation occur by cellular and humoral factors that interact together with local and systemic factors. Surgery produces complex alterations and defects in hemostatic mechanisms, particularly in trauma, cardiac surgery with or without cardiopulmonary bypass, major orthopedic surgery, and neurosurgery. In many patients, multiple quantitative and qualitative hemostatic abnormalities develop as part of surgery, tissue injury, and complex underlying medical conditions. Additionally, the increasing use of multiple anticoagulation agents to treat cardiovascular disease contributes to preexisting perioperative hemostatic defects and increases the potential for bleeding. Furthermore, massive bleeding can produce an acquired hemostatic defect called massive transfusion coagulopathy that is characterized by tissue injury, dilutional hemostatic changes, hypothermia, acidosis, and multiorgan dysfunction.
