Pediatric transthoracic defibrillation: biphasic versus monophasic waveforms in an experimental model

Abstract

Objectives: The purpose of this study was to determine and compare the efficacy of biphasic and monophasic waveforms in a porcine model of pediatric defibrillation. Background: The efficacy and safety of biphasic waveforms in children has not been established. Methods: We initially studied 27 piglets: 12 weighed 3–6 kg (‘infants’), and 15 weighed 7–12 kg (‘children’). Ventricular fibrillation (VF) was induced by rapid right ventricular pacing and maintained for 15 s. Transthoracic shocks of 7–100 J energy were given using monophasic (5 ms truncated exponential) and biphasic (5 ms positive, 5 ms negative pulse, truncated exponential) waveforms. A second study of four ‘infant’ and four ‘child’ piglets utilized the same protocol but with a 10 ms instead of 5 ms monophasic truncated exponential shock waveform compared with the 10 ms biphasic waveform. Results: For both biphasic and monophasic waveforms, shock success rate (termination of VF) rose steadily as energy was increased. In the first study in the ‘infant’ 3–6 kg group, the 10 ms biphasic waveforms were superior to 5 ms monophasic waveforms at 10, 20, and 30 J energies, and in the ‘child’ 7–12 kg group at 20 and 30 J energies ( P<0.05). High success rates (>80%) were achieved by 20 J (4 J/kg) biphasic waveform shocks in the ‘infant’ piglets and 30 J (3 J/kg) biphasic waveform shocks in the ‘child’ piglets. In the second study using a 10 ms monophasic waveform, we found similar results. Pulseless electrical activity occurred in two animals following biphasic shocks and in two animals following monophasic shocks. Conclusions: Biphasic waveforms proved superior to monophasic waveforms in both infant and child models. High success rates were achieved with low-energy biphasic shocks. Biphasic waveform defibrillation is a promising advance in pediatric resuscitation.