title: Effects of biphasic waveforms on outcomes of cardiopulmonary resuscitation in a porcine model of prolonged cardiac arrest.
abstract: OBJECTIVE
  The effects of two clinically available biphasic waveforms on the success of defibrillation and postresuscitation myocardial dysfunction after prolonged ventricular fibrillation were compared with two newly designed dual-path sequential and simultaneous rectilinear biphasic waveforms. Defibrillation via sequential pulses and encircling, overlapping multiple pathway may depolarize a larger myocardial mass and facilitate transthoracic defibrillation.
  
  
  METHODS
  Animal study.
  
  
  METHODS
  Experimental laboratory.
  
  
  METHODS
  Thirty-two 40 +/- 3 kg pigs.
  
  
  METHODS
  Ventricular fibrillation was ischemically induced in 32 pigs. After 7 mins of untreated ventricular fibrillation, cardiopulmonary resuscitation was initiated and continued for 5 mins. Animals were then randomized to receive up to three shocks with a) single-path rectilinear biphasic waveform; b) single-path biphasic truncated exponential waveform; c) dual-path rectilinear biphasic sequential defibrillation; or d) dual-path rectilinear biphasic simultaneous defibrillation.
  
  
  RESULTS
  Rectilinear biphasic, dual-path sequential defibrillation, and simultaneous defibrillation had significantly fewer shocks (1.1 +/- 0.4, 1.4 +/- 0.5, 1.3 +/- 0.7, respectively) before restoration of spontaneous circulation than biphasic truncated exponential waveform (2.6 +/- 1.4, p < .005) and less postresuscitation myocardial dysfunction (p < .05). Also, dual-path sequential defibrillation had higher postresuscitation ejection fraction than rectilinear biphasic and dual-path simultaneous defibrillation (p < .005).
  
  
  CONCLUSIONS
  The energy requirements for terminating ischemically induced ventricular fibrillation were significantly lower and minimized early postresuscitation myocardial dysfunction in the rectilinear biphasic, dual-path sequential defibrillation, and simultaneous defibrillation than the biphasic truncated exponential waveform. Dual-path sequential defibrillation had less postresuscitation myocardial dysfunction than rectilinear biphasic and dual-path simultaneous defibrillation, but at 72 hrs these differences were no longer significant.
authors.affiliation: Weil Institute of Critical Care Medicine, Rancho Mirage, CA, USA.
authors.forename: Yun-Te
authors.initials: YT
authors.lastname: Chang
authors.forename: Wanchun
authors.initials: W
authors.lastname: Tang
authors.forename: Jinglan
authors.initials: J
authors.lastname: Wang
authors.forename: James E
authors.initials: JE
authors.lastname: Brewer
authors.forename: Gary
authors.initials: G
authors.lastname: Freeman
authors.forename: Shijie
authors.initials: S
authors.lastname: Sun
authors.forename: Max Harry
authors.initials: MH
authors.lastname: Weil
mesh_terms: D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000295:instrumentation; D006323:Heart Arrest / Q000150:complications*; D013552:Swine; D014693:Ventricular Fibrillation / Q000209:etiology / Q000628:therapy*