title: One-shock versus three-shock defibrillation protocol significantly improves outcome in a porcine model of prolonged ventricular fibrillation cardiac arrest.
abstract: BACKGROUND
  The success of resuscitation with a 1-shock versus the conventional 3-shock defibrillation protocol was investigated subject to the range of treatment variation imposed by automated external defibrillators (AEDs).
  
  
  RESULTS
  Ventricular fibrillation was induced in 44 domestic pigs. After 7 minutes of untreated VF, animals were randomized among 4 groups representing all combinations of the 1- versus 3-shock protocol and 2 different AED regimens (AED1, AED2). Because few AEDs support a 1-shock protocol, manual defibrillators were used to replicate the AED treatment regimen: electrical waveform, dose sequence, and cardiopulmonary resuscitation (CPR) interruption intervals. Initial shock(s) were delivered, followed by 60 seconds of CPR, and the treatment was repeated until resuscitation was successful or for 15 minutes. The 1-shock protocol was associated with improved outcome, reducing CPR interruptions from 45% to 34% of total resuscitation time (P=0.019) and increasing survival from 64% to 100% (P=0.004). Survival was 91% for AED1 versus 36% for AED2 (P=0.024) with a 3-shock protocol but was increased to 100% for both by adoption of a 1-shock protocol. Improvements in postresuscitation left ventricular ejection fraction and stroke volume were observed with AED1 compared with AED2 (difference of means, 15% and 28% of baseline respectively, P<0.001) regardless of defibrillation protocol.
  
  
  CONCLUSIONS
  Adoption of a 1-shock versus a 3-shock resuscitation protocol improved survival and minimized outcome differences imposed by variations in AED design and implementation. When a conventional 3-shock defibrillation protocol was used, however, the choice of AED had a significant impact on resuscitation outcome.
authors.affiliation: Weil Institute of Critical Care Medicine, 35-100 Bob Hope Dr, Rancho Mirage, California 92270, USA. drsheart@aol.com
authors.forename: Wanchun
authors.initials: W
authors.lastname: Tang
authors.forename: David
authors.initials: D
authors.lastname: Snyder
authors.forename: Jinglan
authors.initials: J
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Yun-Te
authors.initials: YT
authors.lastname: Chang
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; D003243:Consciousness; D047548:Defibrillators; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D004554:Electric Countershock / Q000379:methods*; D004867:Equipment Design; D006323:Heart Arrest / Q000000981:diagnostic imaging / Q000209:etiology / Q000628:therapy*; D006439:Hemodynamics; D008297:Male; D011897:Random Allocation; D020127:Recovery of Function; D034421:Sus scrofa; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000150:complications*