The effects of phase duration on defibrillation success of dual time constant biphasic waveforms

Resuscitation
Yi ShanWanchun Tang

Abstract

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 f...Continue Reading

References

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