ABSTRACT
Objective To compare the effects of biphasic square waveform (BSW) with low or high energy on external defibrillation.Method Adult swine model of closed chest ventricular fibrillation induced by electricity was established.Eighteen swine,weighing (30?3.3) kg were randomly divided into three groups:50-50-50 J group (n=6),30-50-75 J group (n=6),120-150-200 J (n=6).After three minutes of ventricular fibrillation without treatment,the pigs in the three groups were defibrillated accordance to the above sequences. Results 30 J BSW didn't succed to external defibrillate.The first defibrillation successful rate of 50 J and 120 J BSW was 5/6.The total defibrillation successful rate of every group was 100%.All pigs quickly had spontaneous circulation after defibrillation and survived more than 24 hours.ST-T change of low-energy was less than that of high-energy.After resuscitation,myocardial function decreased,but there had not significant differences between groups.Conclusions In the study,30J BSW could not reach successful defibrillation,and 50 J and 120 J BSW had similar defibrillation efficacy.The ideal energy of BSW external defibrillation was 50 J.