Blood coagulation and autologous blood transfusion in cardiac surgery.
OBJECTIVE
To review the basic pathophysiology of altered coagulation associated with cardiopulmonary bypass and autologous blood transfusion in cardiac surgery.


METHODS
Review of rational use of heparin, mechanisms and treatment of coagulation disorders, and autologous blood transfusion.


METHODS
Cardiac surgery in community and academic hospitals.


METHODS
Adult cardiac surgical patients.


RESULTS
Heparin is most commonly used for anticoagulation during cardiopulmonary bypass. Although activated clotting time is widely used to assess heparin-induced anticoagulation, the minimum time to prevent clotting during cardiopulmonary bypass remains unclear. Activated clotting time is affected by many factors other than heparin, such as antithrombin III, blood temperature, platelet count, and age. The rational use of activated clotting time still must be defined. The frequency of abnormal bleeding after cardiopulmonary bypass is significant. Although inadequate surgical hemostasis is the most frequent cause of bleeding, altered coagulation often is present. A decreased number of functional platelets is one of the important causes of bleeding diathesis. Platelet dysfunction is induced by perioperative medication such as aspirin. Cardiopulmonary bypass decreases functional platelets by degranulation, fragmentation, and loss of fibrinogen receptors. Medications such as prostacyclin and iloprost may be useful to protect these platelets. Desmopressin increases factor VIII:C and von Willebrand's factor, leading to a decrease in bleeding time. Desmopressin may be useful to decrease blood loss in repeat cardiac operations, complex cardiac surgery, and abnormal postoperative bleeding. Patients undergoing coronary artery bypass grafting immediately after streptokinase infusion also are at risk for abnormal bleeding. Transfusion of fresh-frozen plasma and cryoprecipitate may be necessary. Autologous blood transfusion is cost-effective and the safest way to avoid or decrease homologous blood transfusion. Predonation, intraoperative salvage, and postoperative salvage are encouraged. Erythropoietin may be useful in increasing the amount of predonation red cells.


CONCLUSIONS
Coagulation disorders in cardiac surgery are caused by many factors, such as heparin, platelet dysfunction, and fibrinolysis. Rational use of blood component therapy and medications such as heparin, protamine, and desmopressin are mandatory. Autologous blood transfusion is very useful in decreasing or obviating the use of homologous blood transfusion.
Inada
E
E
Department of Anaesthesia, Harvard Medical School, Boston, MA.
D000328:Adult; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology*; D001804:Blood Transfusion, Autologous; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D006493:Heparin / Q000494:pharmacology; D006801:Humans
D006493:Heparin