AP019 Efficacy of defibrillation of different biphasic waveforms in high impedance porcinemodel

Abstract

Introduction: Impedance compensation methods and waveforms differ among manufacturers and can play an important role in defibrillation success. Aim of study is to compare efficacy of biphasic quasi-sinusoidal pulse (BQSP) with two truncated exponential pulses (BTEP) on high impedance porcine model. Methods: We evaluated the threshold of defibrillation energy (TDE) in 7 anesthetized pigs (35–62 kg). TDE was defined as the lowest delivered energy that would terminate electrically induced 20 sec VF. MSIEE experimental defibrillator delivered BQSP, BTEP-1 – defibrillator Philips HeartStart MRx and BTEP-2 – Lifepak-12. MSIEE defibrillator compensates high impedance by controlling current with fixed pulse duration (10 ms), while the 2 defibrillators from the USA by prolonging the pulse duration (from 9 to ≥18 ms). The pulses shape and duration corresponded to load resistance 100 ohms regardless of pig chest impedance (41–52 ohms). Results: TDE of BQSP (77.6±15.1 J) was significantly lower, than in BTP-1 by 25% (104.1±14.5 J) and in BTP-2 – by 29% (109.7±12.1 J), p<0.02. Conclusions: The results demonstrate that for transthoracic impedance about 100 ohms the current-based compensation method was more effective than the duration-based compensation technique. The BQSP (named the Gurvich-Venin pulse) has been employed in Russia for about 40 years (clinical efficacy 90–115 J = 80–90%). The first Russian AEDs will generate the optimizing Gurvich-Venin pulse.