Callaham M, Braun O, Valentine W, Clark D M, Zegans C
Division of Emergency Medicine, University of California, San Francisco.
Ann Emerg Med. 1993 Nov;22(11):1664-77. doi: 10.1016/s0196-0644(05)81304-6.
To determine the speed and characteristics of patient response to urban first-responder defibrillation and to determine whether amplitude of ventricular fibrillation (VF) can predict outcome in these patients.
All adult patients in prehospital VF treated by fire department first-responders (265).
A prospective observational study occurring between February 1, 1989, and January 1, 1991. Patients were defibrillated according to advanced cardiac life support and first-responder protocols. ECG and time data were recorded digitally.
Sixty-five percent of patients converted from VF to a more stable rhythm at least once during first-responder monitoring. Fifty-four percent of converted patients refibrillated at least once, and 42% of all stable conversions occurred after at least one episode of refibrillation. Seventy percent of all refibrillations occurred less than six minutes after the defibrillator was turned on, and 23% occurred after more than ten minutes. The proportion of stable conversions decreased from 30% on first conversion to 2% on fourth conversion. With each successive conversion the interval to refibrillation grew shorter, and development of a pulse or blood pressure became less likely. Presence of blood pressure or pulse after conversion had a sensitivity for hospital discharge of 54% and a specificity of 98%. Maximum VF amplitude before countershock was highly predictive of postshock rhythm, stable conversion in the field, time interval before refibrillation, inpatient admission, and hospital discharge. VF amplitude was unrelated to response interval or interval to defibrillation but was positively related to bystander CPR. Logistic regression identified VF amplitude as the most important predictor of hospital discharge; traditional variables such as response interval and bystander CPR were not predictive once amplitude had been accounted for. Changes in VF amplitude during the course of resuscitation efforts were frequent and also predictive of outcome.
Patients in VF who were treated by early countershock refibrillated much more frequently than previously reported. Refibrillations occur both early and late. Initial VF maximum amplitude is strongly predictive of outcome. Future reports of VF cardiac arrest should control for this previously neglected variable. Increased amplitude of VF during repeated refibrillation episodes is associated with increased hospital discharge, so future studies of advanced cardiac life support interventions should explore changes in VF amplitude as an outcome variable.
确定城市急救人员除颤时患者的反应速度和特征，并确定室颤（VF）幅度是否可预测这些患者的预后。
由消防部门急救人员治疗的所有院前室颤成年患者（265例）。
一项前瞻性观察性研究，时间跨度为1989年2月1日至1991年1月1日。患者按照高级心脏生命支持和急救人员方案进行除颤。心电图和时间数据进行数字记录。
65%的患者在急救人员监测期间至少有一次从室颤转为更稳定的心律。54%的转复患者至少再次发生一次室颤，所有稳定转复中有42%发生在至少一次室颤复发之后。所有室颤复发中有70%发生在除颤器开启后不到6分钟，23%发生在10分钟以上。稳定转复的比例从首次转复时的30%降至第四次转复时的2%。随着每次连续转复，至室颤复发的间隔时间缩短，出现脉搏或血压的可能性降低。转复后出现血压或脉搏对出院的敏感性为54%，特异性为98%。除颤前最大室颤幅度对除颤后心律、现场稳定转复、室颤复发前的时间间隔、住院和出院具有高度预测性。室颤幅度与反应间隔或除颤间隔无关，但与旁观者心肺复苏呈正相关。逻辑回归确定室颤幅度是出院的最重要预测因素；一旦考虑了幅度因素，反应间隔和旁观者心肺复苏等传统变量就不具有预测性。复苏过程中室颤幅度的变化很常见，也可预测预后。
早期除颤治疗的室颤患者再次发生室颤的频率比以前报道的要高得多。室颤复发发生在早期和晚期。初始室颤最大幅度对预后有很强的预测性。未来关于室颤心脏骤停的报告应控制这一以前被忽视的变量。反复室颤发作期间室颤幅度增加与出院率增加相关，因此未来关于高级心脏生命支持干预措施的研究应将室颤幅度的变化作为一个结果变量进行探索。
