心肺复苏术后凝血功能改变研究进展
2022-06-12马增文张斌
马增文 张斌
[摘要] 各種原因所引起的心脏骤停是严重的公共卫生问题,提高心脏骤停患者的存活率是现代医学面临的严峻挑战之一。尽管近年来关于心肺复苏的研究取得很大进展,但患者在恢复自主循环后的预后并没有明显改善。心脏骤停可致凝血功能紊乱,引起一系列生理病理改变,严重影响患者预后,目前已有一些针对该病理变化的临床研究,通过常规及新型凝血功能监测手段探究其发生发展规律,且还有一些基础研究不断推理、验证此病理变化的分子层面机制。然而不同原因引起的心脏骤停,其凝血功能改变是存在差异的,在特殊环境下,如高原地区,具有低气压、低氧相对于平原地区具有特殊外部环境,使得高原地区机体凝血机制异常,其心肺复苏后凝血功能变化存在一定特异性,仍需大量研究去进一步探明其中变化影响,为心肺复苏的个体化治疗提供理论依据。本文就心肺复苏后患者凝血功能改变这一临床研究进展进行综述。
[关键词] 心跳骤停;自主循环恢复;心跳骤停后综合征;凝血功能
[中图分类号] R365 [文献标识码] A [文章编号] 1673-9701(2022)14-0194-03
Advances in the study on the alterations of coagulation function after cardiopulmonary resuscitation
MA Zengwen ZHANG Bin
1.Graduate School of Qinghai University, Xining 810016,China; 2.Emergency Intensive Care Unit, Qinghai Provincial People′s Hospital, Xining 810007, China
[Abstract] Cardiac arrest resulted from various causes is a serious public health problem. Improving the survival rate of patients with cardiac arrest has become one of the serious challenges in modern medicine.Despite the great advances in the study on cardiopulmonary resuscitation (CPR) in recent years, the prognosis of patients after the resumption of autonomic circulation has not improved significantly. Cardiac arrest can lead to coagulation disorders and a series of physiological and pathological alterations,which can seriously affect the prognosis of patients. Currently, some clinical studies have been conducted to investigate the development of these pathological alterations by means of conventional and novel coagulation function monitoring, and some basic studies have been conducted to deduce and verify the molecular-level mechanisms of these pathological alterations. However, there are differences in the alterations of coagulation function in cardiac arrest of different causes. For example, in special environments such as plateau areas, the coagulation mechanism of the body tends to be abnormal since air pressure and oxygen there are relatively lower than in plain areas. Besides, there will be certain specificity in the alterations of coagulation function after CPR, and a lot of studies are still required to further investigate the impact of these alterations, so as to provide a theoretical basis for the implementation of individualized CPR. This paper intends to review the advances in the clinical study on the alterations of coagulation function in patients after CPR.
[Key words] Cardiac arrest; Resumption of autonomic circulation; Post-cardiac arrest syndrome; Coagulation function
心脏骤停是世界上很多地区第一位的死亡原因,调查显示美国的心脏骤停病例总数超过35万例/年[1],而我国则超过54万例/年[2],早期复苏成功的患者入院死亡率可高达60%~80%[3],最终30 d存活率不到10%[4]。复苏后综合征(post-cardiac arrest syndrome, PCAS),是复苏患者自主循环恢复(return of spontaneous circulation,ROSC)主要的死亡原因[3,5]。凝血机制异常是PCAS产生的重要原因之一[6],在ROSC患者中,持续存在凝血被激活,抗凝因子减少,纤溶增加等全身凝血障碍的证据。心肺复苏(cardiopulmonary resuscitation,CPR)在近十几年的研究中已取得较大进展,凝血功能改变在心脏骤停、CPR过程中、对患者治疗及预后影响的相关研究也不断深入,本文综述相关的研究进展如下。
1 凝血功能产生的原因及机制
凝血机制被复杂生理及病理过程调控,正常情况下凝血系统与抗凝系统保持动态平衡,在出现心脏骤停等应激事件时被打破,心跳骤停产生的血流停滞、组织缺氧、酸中毒、血小板和白细胞黏附、炎症因子和组织因子释放等多种机制启动凝血过程,导致凝血功能紊乱,在心前骤停前缺氧时间延长、无流速和低流速时间长的患者、无ROSC患者及非幸存者中,这些变化的程度更为严重[7]。除此之外,研究发现ROSC患者蛋白C相关的抗凝途径受损及组织因子抗凝途径的抑制等,同样是导致凝血功能紊乱的重要原因[8]。并且在CPR过程中产生的缺血组织再灌注及所使用的低温、肾上腺素及体外膜肺等治疗方案,将进一步干扰凝血系统,导致凝血功能障碍的进一步加重[9]。引起心脏骤停的原因包括心源性因素及非心源性因素如缺氧、电解质紊乱、体温异常、过敏等[10],主要以心肌梗死、心力衰竭及恶性心率失常等心源性心脏骤停最为常见,其次为呼吸功能不全所引起的心脏骤停[11]。一项初步研究提示[12],不同原因引起的心脏骤停其凝血功能改变存在一定差异,如由于缺氧而发生心脏骤停的PCAS患者更容易患上严重的凝血障碍,与心脏骤停并伴有心源性事件的患者相比,他们的病情与预后更差。其机制可能为低氧性心脏骤停既受循环骤停引起的缺氧的影响,又受心脏骤停前缺氧的影响,随后产生更严重的内皮损伤和凝血纤溶变化,导致其预后不良。
2 凝血功能监测方法
目前凝血功能的常规检测仍是:凝血酶原时间、活化部分凝血活酶时间、血小板、D-二聚体、国际标准化比值、纤维蛋白原等,这些指标早已用于ROSC患者凝血功能监测,并认为其改变与患者神经功能预后相关[13]。然而,凝血是一个复杂的过程,涉及各种因素的相互作用,如凝血因子、纤维蛋白、激活剂、抑制剂和其他相关细胞蛋白,进行常规凝血测试仅能让临床医生了解当时凝血过程的某个阶段,不能完整及时地反映出心脏骤停患者及其在复苏的过程中出现的凝血功能变化[14]。血栓弹力图(thrombelastography,TEG)则是在体外模拟人体凝血功能动态变化,监测纤维蛋白的形成速度、溶解状态和凝块的坚固性、弹性等,其内容涵盖从血小板聚集、凝血到纤溶的整个凝血过程[15]。研究结果表明,凝血的常用值与TEG之间存在良好的相关性[16],目前市面上存在的TEG仪短时间即可出结果,且部分仪器已有自动诊断功能,对ROSC患者凝血功能的改变可及时发现,急诊室心脏复苏期间,TEG所有重要的参数都在大约半小时内得到,可帮助临床医生及时诊断并调整治疗方案,特别是其参考值在对心脏骤停患者的个体化治疗指导及预后的指导存在一定优势[17-18]。
3 监测凝血功能意义
ROSC患者常发生凝血功能紊乱,且在复苏后患者中凝血功能紊乱持续存在,并參与PCAS的发生、发展,对患者病情转归具有及其重要的影响[19],据报道,有凝血障碍的心脏骤停患者的死亡率是无凝血障碍患者的3~4倍[20],因此凝血功能障碍是影响ROSC患者预后的原因之一。心脏骤停后患者凝血功能紊乱的主要改变为凝血功能增强[21],然而实验和临床研究并未证明抗凝剂对心脏骤停和复苏患者是有益的[16]。Satosh等[22]认为,心脏骤停后发生的凝血功能激活、抗凝途径不足、血管内纤维凝块形成等,所引起的脏器功能障碍等一系列病理生理变化符合弥散性血管内凝血(disseminated intravascular coagulation,DIC)的表现。另有研究发现,这种DIC表现是不良预后及早期死亡风险的独立预测因子[7],甚至可预测ROSC患者的神经预后[23-25]。在此观点上认为ROSC患者合并的DIC不是简单的凝血功能紊乱,针对PCAS合并DIC的患者制定相应治疗策略是极其必要的[7]。国内已有学者使用连续性血液净化联合常规方法,对ROSC伴有凝血功能障碍的患者进行治疗并取得一定效果[26],然而该方法对患者远期预后及神经功能恢复的影响仍需多中心大样本量的临床研究数据予以支持。
4 展望
综上所述,凝血功能紊乱贯穿于心脏骤停患者发生、发展、治疗及转归的整个过程中,不同原因引起心脏骤停(心源性、窒息性、失血、休克等)凝血功能障碍生理病理改变过程是有差异的,影响深度也不一样,目前仍需针对病因对ROSC患者的凝血功能改变做进一步研究,为心脏骤停的个体化治疗提供理论依据。在特殊条件下,如高原寒冷缺氧的环境对人凝血状态是影响是明确的[27-28],因此高原地区心脏骤停患者凝血状态的改变及其发展势必有所不同,是否需要行特殊处理,相关研究较少。高原并没有列入心肺复苏指南的特殊环境,高原特殊环境下的心肺复苏在凝血变化方面是否与平原一致,是否应将高原环境列入心肺复苏特殊环境需要进一步研究。TEG与传统凝血监测良好的的相关性,及其所有重要的参数都可以在大约半小时内得到,能够及时准备的识别凝血功能改变,可为临床诊治甚至预后提供迅速且可靠的参考指标。CPR患者凝血功能障碍的治疗尚无单一的临床标准或共识,而在心脏骤停合并DIC诊断的患者中,积极纠正凝血功能紊乱可能是一个合适的治疗目标。
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(收稿日期:2021-11-19)