Utley J R
Division of Cardiac Surgery, Spartanburg Regional Medical Center, South Carolina.
J Card Surg. 1990 Sep;5(3):177-89. doi: 10.1111/j.1540-8191.1990.tb01036.x.
Much of the research related to cardiopulmonary bypass in recent years has been directed toward defining the changes in plasma and blood cells during bypass. In this review, recent information is reexamined for six areas of current interest. These areas are complement activation, immune response, anaphylactic reactions, coagulation, and cerebral dysfunction. Complement may be activated by either the classical or alternate pathway during cardiopulmonary bypass and protamine administration. Membrane oxygenators appear to diminish the degree of complement activation. Complement is a major factor in the whole body inflammatory response; which often accompanies cardiopulmonary bypass. A product of complement activation, C5a- desArg, causes activation and aggregation of granulocytes. Other products of complement activation lead to lysis of blood cells including granulocytes and red cells. Bubble oxygenators appear to have a distinct disadvantage compared to membrane oxygenators regarding infection. Airborne microorganisms are more likely to be entrained into circulating blood with bubble oxygenators than with membrane oxygenators. Bubble oxygenators cause a greater decrease in leukocyte number and function than membrane oxygenators. Anaphylactic reactions have been associated with use of antibiotics, blood products, protamine, and volume expanders during cardiopulmonary bypass. Protamine reactions may be on an immunological basis or due to direct toxicity of the drug. Free radicals including superoxide, hydrogen peroxide, and the hydroxyl radical may be generated during cardiopulmonary bypass and reperfusion. Free radical scavengers including; vitamin E, coenzyme Q, vitamin C, mannitol, and glutathione have been studied. The avoidance of blood transfusion because of risk of transmitted infection including AIDS has become a major goal in cardiac surgery. Factors that correlate with increased transfusion requirement include low hematocrit, female gender, increased age, small body size, low ejection fraction, reoperation, and emergency operation. Heparin resistance due to antithrombin III deficiency is being recognized more commonly. Antithrombin III deficiency may be corrected with fresh frozen plasma. Patients with heparin induced thrombocytopenia may be difficult to manage. Several management protocols are suggested. The most straightforward appears to be the use of aspirin preoperatively and platelet transfusions postoperatively. The incidence of cerebral dysfunction after cardiopulmonary bypass depends on the sensitivity of the test or indicator used. Perioperative stroke is associated with intrinsic cerebrovascular disease and atherosclerosis of the ascending aorta. Retinal angiograms during cardiopulmonary bypass show that microemboli are very common. Cerebroplegia has been shown to extend the period of safe circulatory arrest in animals. Much of the new knowledge concerning cardiopulmonary bypass is the result of close collaboration between cardiac surgeons and nonsurgical scientists.
近年来，许多与体外循环相关的研究都致力于明确体外循环过程中血浆和血细胞的变化。在这篇综述中，重新审视了当前六个感兴趣领域的最新信息。这些领域包括补体激活、免疫反应、过敏反应、凝血和脑功能障碍。在体外循环和使用鱼精蛋白的过程中，补体可能通过经典途径或替代途径被激活。膜式氧合器似乎能降低补体激活的程度。补体是全身炎症反应的主要因素，而全身炎症反应常伴随体外循环发生。补体激活产物C5a-去精氨酸可导致粒细胞的激活和聚集。补体激活的其他产物会导致包括粒细胞和红细胞在内的血细胞溶解。与膜式氧合器相比，鼓泡式氧合器在感染方面似乎有明显劣势。与膜式氧合器相比，鼓泡式氧合器更容易使空气中的微生物进入循环血液。鼓泡式氧合器比膜式氧合器导致白细胞数量和功能的下降幅度更大。过敏反应与体外循环期间使用抗生素、血液制品、鱼精蛋白和扩容剂有关。鱼精蛋白反应可能基于免疫机制，也可能是由于药物的直接毒性。在体外循环和再灌注过程中可能会产生包括超氧阴离子、过氧化氢和羟自由基在内的自由基。人们已经对包括维生素E、辅酶Q、维生素C、甘露醇和谷胱甘肽在内的自由基清除剂进行了研究。由于存在包括艾滋病在内的输血传播感染风险，避免输血已成为心脏手术的一个主要目标。与输血需求增加相关的因素包括低血细胞比容、女性、年龄增长、体型小、射血分数低、再次手术和急诊手术。因抗凝血酶III缺乏导致的肝素抵抗越来越常见。抗凝血酶III缺乏可用新鲜冰冻血浆纠正。肝素诱导的血小板减少症患者可能难以处理。有人提出了几种处理方案。最直接的似乎是术前使用阿司匹林，术后输注血小板。体外循环后脑功能障碍的发生率取决于所使用检测方法或指标的敏感性。围手术期卒中与内在脑血管疾病和升主动脉粥样硬化有关。体外循环期间的视网膜血管造影显示微栓子非常常见。在动物实验中已表明脑麻痹可延长安全循环阻断时间。许多关于体外循环的新知识是心脏外科医生和非外科科学家密切合作的结果。
