院内心脏停搏患者生存率大幅提高

11月15日《新英格兰医学杂志》在线发表的一项大规模登记研究报告显示，近年来美国院内心脏停搏(CA)患者生存率得到大幅改善，并且生存者有临床意义的神经残疾率也有所下降(N. Engl. J. Med. 2012;367:1012-20 [doi: 10.1056/NEJMoa1109148])。

上述结果来自一项针对参加遵循复苏指南登记(GWTG-R)的美国374家医院2000~2009年收治的近85,000例CA患者资料的研究。衣阿华大学医院的SaketGirotra博士及其同事指出，如果上述受益可外推至美国每年发生的大约200,000例CA患者，与2000年相比，2009年将有额外的17,200例患者得以生存，还可以避免超过13,000例的患者出现有临床意义的神经残疾。

鉴于近年来美国已采纳了多项旨在改善复苏治疗质量的措施，但至今尚没有关于这些措施对患者生存率影响的评估研究报告。为此，研究者选择在ICU或病房内发生CA的患者进行分析。由于发生在手术室或急诊室的CA患者临床情况和结局较为复杂，因此未纳入此次分析。

共计84,625例CA患者被纳入分析。初始心率为心脏停搏或无脉性电活动者占79%，心室颤动或无脉性室性心动过速者占21%。主要结局为出院生存，出院生存患者超过14,000例(17%)。

研究期间，所有患者以及2组不同初始心率患者的生存率均呈增加趋势。校正患者时间趋势和医院特点后，总生存率由2000年的13.7%增至2009年的22.3%。无论患者初始心率类型、年龄(小于或大于65岁)、种族或性别如何，所有亚组患者生存率均呈增加趋势。为考察积极改进治疗质量的医院情况，研究者还对GWTG-R登记时间8年以上的85家医院进行单独分析，结果发现上述趋势仍非常明显。

同时，生存者有临床意义的神经残疾率由2000年的32.9%降至2009年的28.1%。生存者重度神经残疾率未见显著变化。

研究者承认该研究没有考察生存率改善的原因。但值得注意的是，对于最初可进行除颤治疗的患者，生存率改善趋势与较短除颤时间无关，表明生存率改善由其他因素所致，而非快速除颤。这些因素可能包括可缩短救治反应时间的CA早期识别，训练有素的人员实施更佳(如不间断)的胸部按压，以及低温治疗和早期心导管术等复苏后治疗手段的改善等。

研究者强调，为更好地了解导致生存率改善的具体因素，以便巩固生存率受益并推广至所有医院，有必要开展更深入的研究。

该研究由美国心脏协会资助。Girotra博士的同事报告与美敦力等多家公司存在利益关系。

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By: MARY ANN MOON, Cardiology News Digital Network

Patient survival after in-hospital cardiac arrest improved substantially in recent years, according to a report from a large registry published online Nov. 15 in the New England Journal of Medicine.

Moreover, the rate of clinically significant neurologic disability among survivors has not risen correspondingly; in fact, it also decreased during the same time period, said Dr. SaketGirotra of the University of Iowa Hospitals and Clinics, Iowa City, and his associates.

These gains were found in a study of nearly 85,000 patients treated at 374 hospitals participating in the Get With the Guidelines (GWTG)-Resuscitation registry, a nationwide, hospital-based, quality-improvement registry documenting all cases of confirmed cardiac arrest at member hospitals in which patients received cardiopulmonary resuscitation. If the findings are extrapolated to the roughly 200,000 such events that occur annually in the United States, "we estimate that an additional 17,200 patients survived to hospital discharge in 2009 as compared with 2000. ... We also estimate that more than 13,000 cases of clinically significant neurologic disability were avoided," the investigators said.

They performed the study because numerous quality-improvement efforts to advance resuscitation care have been adopted in recent years, but no study has yet assessed whether they affected survival.

Dr. Girotra and his colleagues restricted their analysis to patients who had cardiac arrests during 2000-2009 while in an intensive care unit or inpatient ward, excluding cases that occurred in operating rooms, procedural suites, or emergency departments, because events in those settings "have distinct clinical circumstances and outcomes." The study sample comprised 84,625 patients.

The initial cardiac-arrest rhythm was asystole or pulseless electrical activity in 79% and ventricular fibrillation or pulseless ventricular tachycardia in 21%.

The primary outcome of the study was survival to hospital discharge. This was achieved by over 14,000 patients, or 17%.

"There was a significant trend toward increased survival during the study period for all study patients as well as for both rhythm groups. ... After adjustment for temporal trends in patient and hospital characteristics, overall survival increased from 13.7% in 2000 to 22.3% in 2009," the researchers said (N. Engl. J. Med. 2012;367:1012-20 [doi: 10.1056/NEJMoa1109148]).

This gain was seen across all subgroups of patients, regardless of the type of initial heart rhythm, age (younger or older than 65 years), race, or gender. It also remained robust in an analysis restricted to the 85 hospitals that had participated in the GWTG-Resuscitation registry for at least 8 years. This analysis was intended to adjust for the inclusion of centers that were particularly motivated to improve, as compared with other centers.

At the same time, rates of clinically significant neurologic disability among survivors decreased from 32.9% in 2000 to 28.1% in 2009. Rates of severe neurologic disability among survivors did not change significantly over time.

This study was not designed to ascertain the reasons that survival improved over time. However, it was notable that among patients whose initial cardiac rhythm was treatable by defibrillation, improved survival over time was not accompanied by shorter defibrillation times. "This observation suggests that factors other than rapid defibrillation may have accounted for the improvement in survival," Dr. Girotra and his associates said.

Such factors might include earlier recognition of cardiac arrest, leading to shorter response times; greater availability of trained personnel delivering better (i.e., uninterrupted) chest compressions; and improvements in postresuscitation care, such as therapeutic hypothermia and early cardiac catheterization.

More studies are needed "to better understand which specific factors are responsible for improvements in survival after cardiac arrest, so that survival gains can be consolidated and expanded to all hospitals," the investigators said.

This study was funded by the American Heart Association. Dr. Girotra’s associates reported ties to Prescription Solutions, United Health Care, Medtronic, Lumen, and St. Jude Medical.