Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA.
Resuscitation. 2010 Jun;81(6):724-9. doi: 10.1016/j.resuscitation.2010.02.022. Epub 2010 Mar 25.
Pauses for shock delivery in chest compressions are detrimental to the success of resuscitation and may be eliminated with the use of mechanical chest compressors. However, the optimal phasic relationship between mechanical chest compression and defibrillation is still unknown. We therefore undertook a study to assess the effects of timing of defibrillation in the mechanical chest compression cycle on the defibrillation threshold (DFT) using a porcine model of cardiac arrest.
Ventricular fibrillation was electrically induced and untreated for 10s in 8 domestic pigs weighing between 26 and 30 kg. Mechanical chest compression was then continuously performed for 25s, followed by a biphasic electrical shock which was delivered to the animal at 6 randomized coupling phases, including a control phase, with a pre-determined energy setting. The control phase was chosen at a constant 2s following discontinued chest compression. A novel grouped up-and-down DFT testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 min, the testing sequence was repeated, resulting in a total of 60 test shocks delivered to each animal.
No difference between the delivered shock energy, voltage and current were observed among the 6 study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of mechanical chest compression.
Defibrillation efficacy is maximal when electrical shock is delivered in the upstroke phase of mechanical chest compression.
在胸外按压中暂停电击会对复苏的成功产生不利影响，而使用机械胸外按压机能消除这种影响。然而，机械胸外按压与除颤之间的最佳相位关系仍然未知。因此，我们进行了一项研究，使用猪心搏骤停模型评估机械胸外按压周期中除颤时间对除颤阈值（DFT）的影响。
在 8 头体重 26 至 30 公斤的家猪中，通过电刺激诱发心室颤动并对其不进行治疗 10 秒。然后，连续进行 25 秒的机械胸外按压，接着给予双相电冲击，该冲击在 6 个随机耦合阶段中给予动物，包括一个预定能量设置的对照阶段。对照阶段选择在机械胸外按压停止后固定的 2 秒。采用一种新型分组上下 DFT 测试方案来比较不同耦合阶段的成功率。在 4 分钟的恢复间隔后，重复测试序列，每个动物共接受 60 次测试冲击。
在 6 个研究阶段中，所传递的冲击能量、电压和电流之间没有差异。然而，当电击在机械胸外按压的上升阶段传递时，除颤成功率显著更高。
当电冲击在机械胸外按压的上升阶段传递时，除颤效果最佳。
