title: Comparison of outcomes after use of biphasic or monophasic defibrillators among out-of-hospital cardiac arrest patients: a nationwide population-based observational study.
abstract: BACKGROUND
  The use and popularity of the biphasic waveform defibrillator as a replacement for the monophasic waveform defibrillator are increasing, but it is unclear whether this can improve the rate of survival among out-of-hospital cardiac arrest patients. This study aimed to verify the hypothesis that the outcome of out-of-hospital cardiac arrest patients who received defibrillation shock with the biphasic waveform defibrillator was better than that of patients who received defibrillation shock with the monophasic defibrillator.
  
  
  RESULTS
  This prospective, nationwide, population-based, observational study included 21 172 out-of-hospital cardiac arrest patients with initial ventricular fibrillation or pulseless ventricular tachycardia from January 1, 2005, through December 31, 2007. Defibrillation shock was performed by monophasic defibrillator on 8224 (39%) patients and by biphasic defibrillator on 12 948 (61%) patients. The rate of survival at 1 month with minimal neurological impairment was 11.6% (951/8192) in the monophasic defibrillator group and 12.8% (1653/12 928) in the biphasic defibrillator group. Hierarchical logistic regression analysis using a generalized estimation equation showed no significant difference between the biphasic and monophasic groups in 1-month survival with minimal neurological impairment (adjusted odds ratio, 1.07; 95% confidence interval, 0.91-1.26; P=0.42). Confirmatory propensity score analyses showed similar results.
  
  
  CONCLUSIONS
  Although monophasic defibrillators are being replaced by biphasic defibrillators, our nationwide population-based observational study failed to demonstrate a statistically significant association between defibrillation waveform and 1-month survival rate with minimal neurological impairment.
authors.affiliation: Emergency Life-Saving Technique Academy of Tokyo, 4–5 Minamiosawa, Hachioji, Tokyo, Japan. tseizan@gmail.com
authors.forename: Seizan
authors.initials: S
authors.lastname: Tanabe
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasunaga
authors.forename: Toshio
authors.initials: T
authors.lastname: Ogawa
authors.forename: Soichi
authors.initials: S
authors.lastname: Koike
authors.forename: Manabu
authors.initials: M
authors.lastname: Akahane
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Horiguchi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hatanaka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yokota
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Imamura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D047548:Defibrillators / Q000009:adverse effects; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D004867:Equipment Design; D005260:Female; D019538:Health Care Surveys; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D057216:Propensity Score; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome