Murkin J M
Department of Anesthesia, University Campus, London Health Sciences Center, Ontario, Canada.
J Cardiothorac Vasc Anesth. 1999 Aug;13(4 Suppl 1):12-7; discussion 36-7.
The frequency and severity of central nervous system complications in patients undergoing cardiopulmonary bypass (CPB) may be greater than previously thought, particularly in the older population. The risks of embolic neurologic complications and stroke in the population older than 70 years from a severely atherosclerotic ascending aorta are well documented. Moreover, while the majority of CPB patients do not experience perioperative stroke, a high incidence of more subtle central nervous system dysfunction has been demonstrated to persist for up to 1 year after surgery. This report reviews the incidence and severity of cerebral injury during CPB and the effects of both age and the severely atherosclerotic ascending aorta on adverse neurologic outcomes. It discusses perioperative diagnostic methods, including transesophageal echocardiography, periaortic echocardiography, transcranial Doppler, and retinal fluorescein angiography, and the benefit of pH management. Ischemic brain injury resulting from activation of injury-related enzymes as part of the systemic inflammatory response is briefly reviewed. Age has been shown to be the strongest predictor of neurologic sequelae in patients undergoing CPB. The risk of embolic complications in the brain also increases in proportion to the degree of atherosclerosis in the ascending aorta, which is age-related. Transesophageal echocardiography has been found to be only partly useful in diagnosing these lesions or in guiding surgical manipulations in comparison with epiaortic imaging, which is more discreet. Transcranial Doppler and retinal fluorescein angiography have provided further evidence of microemboli during surgical manipulations. In a 316-patient prospective study, we found no differences in outcome between pH-stat and alpha-stat strategies during moderate hypothermic CPB, except in patients who were on bypass for more than 90 minutes. Approximately 90% of these had a significant reduction in cognitive impairment with the alpha-stat method. Aprotinin, a serine protease inhibitor, has been found in two separate, randomized, placebo-controlled trials to significantly lower incidences of perioperative stroke. Further study to develop therapeutic and preemptive strategies for prevention of brain injury is required, especially in the elderly. Aprotinin and other modalities aimed at suppressing the inflammatory response to CPB may offer hope because they act to suppress injury-provoking enzymes and leukocyte activation that are, in part, responsible for organ system dysfunction following CPB.
接受体外循环（CPB）的患者中枢神经系统并发症的发生率和严重程度可能比之前认为的更高，尤其是在老年人群中。严重动脉粥样硬化的升主动脉导致70岁以上人群发生栓塞性神经并发症和中风的风险已有充分记录。此外，虽然大多数CPB患者在围手术期未发生中风，但已证明术后长达1年持续存在较高发生率的更为隐匿的中枢神经系统功能障碍。本报告回顾了CPB期间脑损伤的发生率和严重程度，以及年龄和严重动脉粥样硬化的升主动脉对不良神经结局的影响。它讨论了围手术期诊断方法，包括经食管超声心动图、主动脉周围超声心动图、经颅多普勒和视网膜荧光血管造影，以及pH管理的益处。简要回顾了作为全身炎症反应一部分的损伤相关酶激活导致的缺血性脑损伤。年龄已被证明是接受CPB患者神经后遗症的最强预测因素。脑栓塞并发症的风险也与升主动脉粥样硬化程度成正比增加，而升主动脉粥样硬化与年龄相关。与更为精确的主动脉外膜成像相比，经食管超声心动图在诊断这些病变或指导手术操作方面仅部分有用。经颅多普勒和视网膜荧光血管造影提供了手术操作期间微栓子的进一步证据。在一项对316例患者的前瞻性研究中，我们发现中度低温CPB期间pH稳态和α稳态策略在结局上无差异，但体外循环时间超过90分钟的患者除外。其中约90%的患者采用α稳态方法后认知障碍显著减轻。抑肽酶是一种丝氨酸蛋白酶抑制剂，在两项独立的随机安慰剂对照试验中发现其可显著降低围手术期中风的发生率。需要进一步研究制定预防脑损伤的治疗和预防性策略，尤其是在老年人中。抑肽酶和其他旨在抑制对CPB炎症反应的方法可能带来希望，因为它们可抑制引发损伤的酶和白细胞激活，而这些在一定程度上是CPB后器官系统功能障碍的原因。
