Heavens J P, Cleland M J, Maloney J P, Rowe B H
Ottawa-Carleton Base Hospital Program, Ottawa General Hospital, University of Ottawa, Ontario, Canada.
Ann Emerg Med. 1998 Aug;32(2):191-9. doi: 10.1016/s0196-0644(98)70136-2.
To assess whether transthoracic impedance and peak current are determinants of defibrillation success in patients with out-of-hospital ventricular fibrillation (VF).
A retrospective cohort study was carried out in a suburban Canadian EMS system. Participants were patients who experienced out-of-hospital cardiac arrest in the regional municipality of Ottawa-Carleton, had VF rhythm at presentation, and received countershocks from the Laerdal Heartstart 2000 automated external defibrillator.
A total of 310 patients met the inclusion criteria. Collectively they received 717 countershocks. The first shocks were successful in converting VF rhythm 25.5% of the time. The most important determinant of shock success was the interval from when the call was received until delivery of the first shock (P<.01). Length of time at scene, current, impedance, and patient age were not significant determinants of success of first shock. The time interval until first shock was also a determinant of survival (P<.01). EMS response time, whether the arrest was witnessed, initial impedance, and current were not determinants of survival.
OHCA shock success and survival are associated with EMS system factors such as the interval from when the call was received until delivery of the first shock. The importance of impedance and peak current remain theoretic for out-of-hospital defibrillation success and did not influence defibrillation success in this study.
评估经胸阻抗和峰值电流是否为院外心室颤动（VF）患者除颤成功的决定因素。
在加拿大一个郊区的急救医疗服务（EMS）系统中开展了一项回顾性队列研究。参与者为在渥太华 - 卡尔顿地区自治市发生院外心脏骤停、就诊时为VF心律且接受了Laerdal Heartstart 2000自动体外除颤器电击的患者。
共有310名患者符合纳入标准。他们总共接受了717次电击。首次电击成功转复VF心律的时间占25.5%。电击成功的最重要决定因素是从接到呼叫到首次电击的时间间隔（P<0.01）。现场停留时间、电流、阻抗和患者年龄不是首次电击成功的显著决定因素。到首次电击的时间间隔也是生存的一个决定因素（P<0.01）。急救医疗服务响应时间、心脏骤停是否被目击、初始阻抗和电流不是生存的决定因素。
院外心脏骤停电击成功和生存与急救医疗服务系统因素相关，如从接到呼叫到首次电击的时间间隔。阻抗和峰值电流对于院外除颤成功的重要性仍停留在理论层面，在本研究中并未影响除颤成功。
