Circulation：心脏骤停发生时间不同预后有差异

图：A，按小时分的院前自主循环恢复（ROSC）率。总体院前ROSC占12.3%（实线），夜间占11.6%（短横线），日间占12.8%（点线）。日间和夜间无统计学差异（P=0.20）。B.根据小时分的30天生存率。总体30天生存率为9.92%（实线），夜间为8.56%（短横），日间为10.9%（点线），二者有统计学差异（P=0.02）。
在美国每年有超过30万人发生院外心脏骤停（out-of-hospital cardiac arrests ，OHCA）。这些患者成功复苏的关键在于急救医疗服务、早期高质量胸外按压的心肺复苏、除颤、高级生命支持措施和进入医院后的复苏治疗有效实施。曾有研究报道院内患者发生心脏骤停的生存率因发生时间不同对预后有影响，其中夜间发生患者的自主循环恢复和存活出院比例较低，即使在考虑到疾病类型等各种混杂因素后依然有类似结果。目前没有在有院外急救情况下OHCA的发生时间与预后关系的研究。这种相关性或许会对急诊人员分配、训练和资源调配有重要意义。出于上述目的，来自美国宾夕法尼亚州的急诊专家Roger A等研究人员对费城急救医疗服务系统的心脏骤停患者的数据进行回顾性分析。他们发现即使经患者自身情况、发生的事件和院前急救差异等因素校正后，OHCA日间发生患者的30天生存率仍高于夜间发生患者。该研究结果发表在2013年4月16日的Circulation杂志上。
研究纳入2008年1月至2012年2月间的成人OHCA患者（大于等于18岁），除外创伤性死亡和未行心肺复苏的病例。将一天的时间分组定义，日间为上午8点到下午7点59分，夜间为下午8点至次日上午7点59分，该12小时时间段的选取参照了研究期间内急诊人员的换班时间。采用相对风险回归模型评价OHCA在一天内发生时间和院前自主循环恢复以及30天生存情况之间的关系，并经临床相关生存预测因素校正。
在4789例患者中，有 1962 例患者（41.0%） OHCA的发生时间在夜间。所有患者平均年龄为63.8岁（SD, 17.4年）；男性占到54.5%。夜间发生 OHCA 患者的院前自主循环恢复率并不低于日间发生OHCA 患者（11.6% 比12.8%; P=0.20）。但夜间发生的患者30天内的生存率较低（8.56% 比 10.9%; P=0.02）。经人口学特征、发作心律、最终现场、呼叫时间、抵达现场所用时间、自动体外除颤器应用、旁观者的心肺复苏及所处位置等因素校正后，分析显示OHCA日间发生患者的30天的生存率仍明显较高，相对危险度为1.10（95%CI，1.02–1.18）。
研究人员认为，夜间存活率下降的原因可能是夜间患者的自身生理情况、参与救治人员的体力和精神状态降低，或心肺复苏质量和其他治疗措施差异所致。这需要进一步研究提高夜间紧急医疗服务的复苏质量，改善患者院外OHCA后生存率。
与心脏骤停相关的拓展阅读：

• 2013AHA 美国提高院内心脏骤停生存率策略的共识建议
• Neurology：心脏骤停后的脑电图与临床转归
• Circulation：ICDs可降低院外室颤性心脏骤停率
• 处理院外心脏骤停，复苏有功
• 非专业救援者单纯按压CPR和心脏骤停患者的出院生存
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Effect of Time of Day on Prehospital Care and Outcomes After Out-of-Hospital Cardiac Arrest.
BACKGROUND
More than 300 000 out-of-hospital cardiac arrests (OHCA) occur each year in the United States. The relationship between time of day and OHCA outcomes in the prehospital setting is unknown. Any such association may have important implications for emergency medical services resource allocation.
METHODS AND RESULTS
We performed a retrospective review of cardiac arrest data from a large, urban emergency medical services system. Included were OHCA occurring in adults from January 2008 to February 2012. Excluded were traumatic arrests and cases in which resuscitation measures were not performed. Day was defined as 8 am to 7:59 pm; night, as 8 pm to 7:59 am. A relative risk regression model was used to evaluate the association between time of day and prehospital return of spontaneous circulation and 30-day survival, with adjustment for clinically relevant predictors of survival. Among the 4789 included cases, 1962 (41.0%) occurred at night. Mean age was 63.8 years (SD, 17.4 years); 54.5% were male. Patients with an OHCA occurring at night did not have significantly lower rates of prehospital return of spontaneous circulation compared with patients having daytime arrests (11.6% versus 12.8%; P=0.20). However, rates of 30-day survival were significantly lower at night (8.56% versus 10.9%; P=0.02). After adjustment for demographics, presenting rhythm, field termination, duration of call, dispatch-to-scene interval, automated external defibrillator application, bystander cardiopulmonary resuscitation, and location, 30-day survival remained significantly higher after daytime OHCA, with a relative risk of 1.10 (95% confidence interval, 1.02-1.18).
CONCLUSION
Rates of 30-day survival were significantly higher for OHCA occurring during the day compared with at night, even after adjustment for patient, event, and prehospital care differences.