可预测院内复苏后神经功能良好生存的模型问世

研究者已经开发出简单的床旁预测模型[院内心脏骤停复苏后生存(CASPRI)评分]，用于帮助临床医生估计哪些院内心脏骤停复苏患者能够以良好的神经功能状态存活至出院(Arch. Intern. Med. 2012 May 28 [doi:10.1001/archinternmed.2012.2050])。

在这项研究中，圣卢克美国中部心脏研究所的Paul S. Chan博士及其同事采用来自“遵循指南-复苏”(Get With the Guidelines Resuscitation)登记处(前身为美国国立心肺复苏登记处)的数据来开发这一预测模型。研究对象是2000~2009年美国551家医院住院病房或重症监护病房的42,957例成功复苏的患者。患者平均年龄为66岁，56%为男性，19%为黑人。

研究者首先确定了37个基线因素在预测28,629例患者(此为推导队列)预后方面的价值。这些因素包括患者人口学特征(如年龄和性别)；心脏骤停发生的地点(院内)；初始心脏骤停节律；心脏骤停发生的时间点(常规工作时间或下班后)；心脏骤停前的神经功能状况；合并症；心脏骤停发生时已实施的重症干预(如机械通气或血管加压药)；以及关键心脏因素(如实施复苏措施的时程及至除颤的时间)。

从这一分析中，研究者发现11个因素最能够预测神经功能完整的生存。他们使用这些因素构建预测模型和表格，将结果转换成风险评分(1~140分)，总分越高表明获得神经功能良好的生存的概率越低。其中2个预测能力最大的因素是与心脏骤停本身相关的因素：初始心脏骤停节律和复苏直至自主循环恢复的时程。相比之下，许多患者因素不具有预测能力而被剔除。

研究者随后对剩余的14,328例患者进行验证研究，以检验CASPRI评分的准确性。结果显示，最高十分位数(CASPRI评分低于10分)的患者以神经功能良好状态生存的平均概率是70.7%，而最低十分位数(CASPRI 评分≥28分)的患者仅为2.8%。

在随刊述评中，华盛顿大学海景院前急救护理中心的Ella Huszti博士和Graham Nichol博士指出，该研究存在一些局限性，包括可能存在选择偏倚、对心脏骤停前神经功能状态的事后评价可能不准确，以及缺乏有关如何正确使用该模型的指导。由于存在这些局限性，因此在临床上前瞻性使用该模型时应谨慎(Arch. Intern. Med. 2012 May 28 [doi:10.1001/archinternmed.2012.2279])。

该研究获美国国立心肺血液研究所及美国心脏学会(AHA)支持。Nichol博士与MedicOne基金会、AHA和Sotera Wireless公司存在联系。

Researchers have developed a simple bedside prediction tool – the CASPRI score – to help clinicians estimate which patients resuscitated from in-hospital cardiac arrest will survive to discharge with favorable neurologic status and which will not, according to a report published in the Archives of Internal Medicine.

“We believe that this tool is simple to use, addresses a critical unmet need for better prognostication after cardiac arrest, and has the potential to enhance communication with patients and families,” said Dr. Paul S. Chan of Saint Luke’s Mid-America Heart Institute, Kansas City, Missouri, and his associates.

They used data from the Get With the Guidelines Resuscitation registry (formerly the U.S. National Registry of Cardiopulmonary Resuscitation) to develop this prediction tool, noting that families and caregivers “are eager for more precise information about the likelihood of survival and neurologic outcome” when patients have survived in-hospital resuscitation.

The investigators assessed the cases of 42,957 patients in inpatient wards or intensive care units at 551 U.S. hospitals in 2000-2009 who were successfully resuscitated. The mean patient age was 66 years. Fifty-six percent of the cohort was male, 19% was African American.

The first step in developing their prediction tool, known as the Cardiac Arrest Survival Post-Resuscitation In-Hospital (CASPRI) score, was to determine the value of 37 baseline characteristics in predicting the outcomes of the 28,629 subjects who composed the derivation cohort. These characteristics included patient demographics such as age and sex; the location (within the hospital) of the arrest; the initial cardiac arrest rhythm; the timing of the arrest (during regular work hours or off-hours); the patient’s neurologic status before the cardiac arrest; comorbidities; critical care interventions already in place at the time of the cardiac arrest, such as mechanical ventilation or vasopressor medications; and key cardiac variables such as the duration of resuscitation efforts and time to defibrillation.

From this analysis, the researchers identified the 11 variables with the greatest ability to predict neurologically intact survival. They used those variables to construct a predictive model, and a table for converting the results into a numerical risk score from 1 to 40 points, with higher a total indicating a lower likelihood of favorable neurologic survival.

It was notable that two variables found to have the greatest predictive ability were factors pertaining to the cardiac arrest itself: the initial cardiac arrest rhythm, and the duration of resuscitation until spontaneous circulation was restored. In contrast, many patient factors were not found to be predictive and were discarded from the final model, the investigators said (Arch. Intern. Med. 2012 May 28 [doi:10.1001/archinternmed.2012.2050]).

Dr. Chan and his colleagues then conducted a validation study to test the accuracy of the CASPRI score in the remaining 14,328 subjects. “Patients in the top decile (CASPRI score of less than 10) had a 70.7% mean probability of favorable neurologic survival, whereas patients in the bottom decile (CASPRI score of 28 or higher) had a 2.8% mean probability of favorable neurologic survival,” they noted.

“Providing concrete probabilities for favorable neurologic survival after cardiac arrest is an important discussion that clinicians have with patients and their families to manage expectations. By converting our prediction model into a risk score, we have sought to create an infrastructure with which clinicians can identify [the] 10% of patients ... who have a greater than 70% probability of favorable neurologic survival to discharge, compared with another 10% who have less than a 3% chance of this outcome,” they added.

This study was supported by the National Heart, Lung, and Blood Institute and the American Heart Association.

‘Mostly Dead’ Is Still ‘Slightly Alive’

There were some limitations to the approach by Chan et al. in developing their prediction model, including possible selection bias, the potential inaccuracy of a post hoc assessment of prearrest neurologic status, and a lack of guidance as to exactly when the tool is to be used, Ella Huszti, Ph.D, and Dr. Graham Nichol wrote in an editorial (Arch. Intern. Med. 2012 May 28 [doi:10.1001/archinternmed.2012.2279]).

“We note that the easiest way to reduce the large regional variation in outcome after the onset of cardiac arrest [is] to not attempt resuscitation of any patient or to withdraw care from all patients who seemingly have a poor prognosis. But that strategy would obviously be unacceptable to most of the public and health care providers,” they wrote.

Given the study’s limitations, “we urge caution to those who consider applying the [tool] prospectively to guide clinical practice.”

“As Miracle Max noted in the Rob Reiner film, ‘The Princess Bride’ (1987): ‘There’s a big difference between mostly dead and all dead. Mostly dead is slightly alive.’ Most members of the public would want health care providers to persevere in caring for a patient who is slightly alive,” they noted.

Dr. Huszti and Dr. Nichol are at the University of Washington–Harborview Center for Prehospital Emergency Care, Seattle. Dr. Nichol reported ties to MedicOne Foundation, the AHA, and Sotera Wireless.