Inada E
Department of Anaesthesia, Harvard Medical School, Boston, MA.
J Clin Anesth. 1990 Nov-Dec;2(6):393-406. doi: 10.1016/0952-8180(90)90026-y.
To review the basic pathophysiology of altered coagulation associated with cardiopulmonary bypass and autologous blood transfusion in cardiac surgery.
Review of rational use of heparin, mechanisms and treatment of coagulation disorders, and autologous blood transfusion.
Cardiac surgery in community and academic hospitals.
Adult cardiac surgical patients.
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.
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.
回顾心脏手术中与体外循环及自体输血相关的凝血改变的基本病理生理学。
回顾肝素的合理使用、凝血障碍的机制及治疗以及自体输血。
社区医院和学术医院的心脏手术。
成年心脏手术患者。
肝素是体外循环期间最常用的抗凝剂。尽管活化凝血时间被广泛用于评估肝素诱导的抗凝作用，但体外循环期间防止凝血的最短时间仍不清楚。活化凝血时间受肝素以外的许多因素影响，如抗凝血酶III、体温、血小板计数和年龄。活化凝血时间的合理使用仍有待确定。体外循环后异常出血的发生率很高。尽管手术止血不充分是出血最常见的原因，但凝血改变也常常存在。功能性血小板数量减少是出血倾向的重要原因之一。血小板功能障碍由围手术期用药如阿司匹林引起。体外循环通过脱颗粒、破碎和纤维蛋白原受体丧失减少功能性血小板。前列环素和伊洛前列素等药物可能有助于保护这些血小板。去氨加压素增加因子VIII:C和血管性血友病因子，导致出血时间缩短。去氨加压素可能有助于减少再次心脏手术、复杂心脏手术和术后异常出血时的失血量。链激酶输注后立即接受冠状动脉搭桥术的患者也有异常出血的风险。可能需要输注新鲜冰冻血浆和冷沉淀。自体输血具有成本效益，是避免或减少异体输血的最安全方法。鼓励术前采血、术中血液回收和术后血液回收。促红细胞生成素可能有助于增加术前采血量。
心脏手术中的凝血障碍由多种因素引起，如肝素、血小板功能障碍和纤维蛋白溶解。必须合理使用血液成分疗法以及肝素、鱼精蛋白和去氨加压素等药物。自体输血在减少或避免使用异体输血方面非常有用。
