Blouin D, Topping C, Moore S, Stiell I, Afilalo M
Emergency Department, Jewish General Hospital, McGill University, Montreal, Canada.
Ann Emerg Med. 2001 Sep;38(3):256-61. doi: 10.1067/mem.2001.116596.
The American Heart Association protocols for use of automated external defibrillators (AEDs) recommend that a rhythm analysis be done immediately after each defibrillation attempt. However, shock is often followed by electrical silence or marginally organized electrical activity before ventricular fibrillation (VF) or ventricular tachycardia (VT) recurs. The optimal timing of postshock analysis for identification of recurrent VF/VT is unknown. This study examines the time to recurrence of VF/VT after a defibrillation attempt with AED.
Over an 18-month period, all tapes from patients with out-of-hospital cardiac arrest who received shocks at least once with an AED were screened for recurrent VF/VT. All cases come from a single emergency medical services system providing basic life support, defibrillation with AED, and intubation with an esophageal-tracheal twin-lumen airway device (Combitube) for a population of 633,511 individuals. Pediatric and traumatic cases were excluded. When VF/VT recurred within 3 minutes of the defibrillation attempt, rhythm strips were printed and included in the study. Two cardiology fellows, blinded to the study objectives, measured the time from defibrillation to recurrent VF/VT for each strip.
Over the study period, 222 tapes from 96 patients met the inclusion criteria. Only 44 (20%) occurrences of VF/VT had recurred within 6 seconds of defibrillation, 162 (73%) at 60 seconds, and 200 (90%) at 90 seconds.
Eighty percent of VF/VT recurred more than 6 seconds after defibrillation and were missed when using current American Heart Association AED protocols. Subsequent analysis should be postponed until at least 30 seconds after defibrillation. Performing 30 seconds of chest compressions after defibrillation before subsequent AED rhythm analysis would increase AED identification of VF/VT to 52%.
美国心脏协会关于使用自动体外除颤器（AED）的方案建议，在每次除颤尝试后应立即进行心律分析。然而，电击后在室颤（VF）或室性心动过速（VT）复发之前，常出现电静止或微弱的有组织电活动。用于识别复发性VF/VT的电击后分析的最佳时机尚不清楚。本研究探讨使用AED进行除颤尝试后VF/VT复发的时间。
在18个月的时间里，对所有院外心脏骤停且至少接受过一次AED电击的患者的磁带进行筛查，以寻找复发性VF/VT。所有病例均来自一个单一的紧急医疗服务系统，该系统为633511人提供基本生命支持、AED除颤以及使用食管气管双腔气道装置（食管气管联合导管）进行插管。排除儿科和创伤性病例。当VF/VT在除颤尝试后3分钟内复发时，打印心律条并纳入研究。两名对研究目的不知情的心脏病学研究员测量每条心律条从除颤到复发性VF/VT的时间。
在研究期间，来自96名患者的222份磁带符合纳入标准。只有44次（20%）VF/VT发作在除颤后6秒内复发，162次（73%）在60秒时复发，200次（90%）在90秒时复发。
80%的VF/VT在除颤后6秒以上复发，按照当前美国心脏协会的AED方案会漏诊。后续分析应推迟到除颤后至少30秒。在后续AED心律分析之前，除颤后进行30秒的胸外按压将使AED对VF/VT的识别率提高到52%。
