title: Average current is better than peak current as therapeutic dosage for biphasic waveforms in a ventricular fibrillation pig model of cardiac arrest.
abstract: OBJECTIVE
  Defibrillation current has been shown to be a clinically more relevant dosing unit than energy. However, the effects of average and peak current in determining shock outcome are still undetermined. The aim of this study was to investigate the relationship between average current, peak current and defibrillation success when different biphasic waveforms were employed.
  
  
  METHODS
  Ventricular fibrillation (VF) was electrically induced in 22 domestic male pigs. Animals were then randomized to receive defibrillation using one of two different biphasic waveforms. A grouped up-and-down defibrillation threshold-testing protocol was used to maintain the average success rate of 50% in the neighborhood. In 14 animals (Study A), defibrillations were accomplished with either biphasic truncated exponential (BTE) or rectilinear biphasic waveforms. In eight animals (Study B), shocks were delivered using two BTE waveforms that had identical peak current but different waveform durations.
  
  
  RESULTS
  Both average and peak currents were associated with defibrillation success when BTE and rectilinear waveforms were investigated. However, when pathway impedance was less than 90Ω for the BTE waveform, bivariate correlation coefficient was 0.36 (p=0.001) for the average current, but only 0.21 (p=0.06) for the peak current in Study A. In Study B, a high defibrillation success (67.9% vs. 38.8%, p<0.001) was observed when the waveform delivered more average current (14.9±2.1A vs. 13.5±1.7A, p<0.001) while keeping the peak current unchanged.
  
  
  CONCLUSIONS
  In this porcine model of VF, average current was better than peak current to be an adequate parameter to describe the therapeutic dosage when biphasic defibrillation waveforms were used. The institutional protocol number: P0805.
authors.affiliation: School of Biomedical Engineering, Third Military Medical University and Chongqing University, Chongqing, China.
authors.forename: Bihua
authors.initials: B
authors.lastname: Chen
authors.affiliation: Emergency Department, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ristagno
authors.affiliation: ZOLL Medical Corporation, Chelmsford, MA, USA.
authors.forename: Weilun
authors.initials: W
authors.lastname: Quan
authors.affiliation: School of Biomedical Engineering, Third Military Medical University and Chongqing University, Chongqing, China. Electronic address: leeoken@gmail.com.
authors.forename: Yongqin
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000379:methods*; D006323:Heart Arrest / Q000628:therapy*; D008297:Male; D034421:Sus scrofa; D013552:Swine; D014693:Ventricular Fibrillation / Q000628:therapy*
keywords: Average current; Cardiac arrest; Peak current; Shock success; Ventricular fibrillation