Weil Institute of Critical Care Medicine, Rancho Mirage, CA 92270, USA.
Resuscitation. 2010 Feb;81(2):236-41. doi: 10.1016/j.resuscitation.2009.10.022. Epub 2009 Nov 27.
The effects of first and second phase duration of biphasic waveforms on defibrillation success were evaluated in a guinea pig model of ventricular fibrillation (VF). We hypothesized that waveform duration, and especially the first phase duration, played a main role on defibrillation efficacy in comparison to energy, current and voltage, when a dual time constant biphasic shock was employed.
VF was induced and untreated for 5s in 30 male guinea pigs, prior to attempting a single defibrillatory shock with one of 5 defibrillation waveforms which had different durations of the first and second phase. A five step up-down protocol was utilized for determining the defibrillation efficacy. After a 3-min interval, the procedure was repeated. A total of 25 cardiac arrest events and defibrillations were investigated for each animal.
The defibrillation waveforms with an intermediate first phase of 5 ms, yielded the highest defibrillation success (p<0.05). These waveforms also presented significantly lower energy, current and voltage in comparison to waveforms with shorter or longer first phase durations (p<0.001). However, no differences on defibrillation success were observed among waveforms with different second phase durations varying from 1.5 ms to 3.5 ms.
For dual time constant biphasic waveforms, the first phase duration played a main role on defibrillation success. The intermediate first phase duration of 5 ms, yielded the best defibrillation efficacy compared with shorter or longer first phase durations. While the second phase duration did not affect defibrillation outcomes.
本研究旨在评估双相波的第一和第二相持续时间对室颤（VF）豚鼠模型除颤成功的影响。我们假设，在使用双时相常数双相波时，与能量、电流和电压相比，波形持续时间，尤其是第一相持续时间，对除颤效果起着主要作用。
在 30 只雄性豚鼠中诱导 VF 并使其未经治疗持续 5s，然后使用具有不同第一相和第二相持续时间的 5 种除颤波形之一尝试单次除颤。采用五步升-降法确定除颤效果。间隔 3 分钟后，重复该程序。每个动物共进行 25 次心脏骤停事件和除颤。
第一相持续时间为 5ms 的除颤波形，除颤成功率最高（p<0.05）。与第一相持续时间较短或较长的波形相比，这些波形的能量、电流和电压也显著降低（p<0.001）。然而，不同第二相持续时间（1.5ms 至 3.5ms）的波形之间，除颤成功率无差异。
对于双时相常数双相波，第一相持续时间对除颤成功率起着主要作用。与较短或较长的第一相持续时间相比，5ms 的中间第一相持续时间可获得最佳的除颤效果。而第二相持续时间不影响除颤效果。
