title: Biphasic versus monophasic defibrillation in out-of-hospital cardiac arrest: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Biphasic defibrillation is more effective than monophasic one in controlled in-hospital conditions. The present review evaluated the performance of both waveforms in the defibrillation of patients of out-of-hospital cardiac arrest (OHCA) with initial ventricular fibrillation (Vf) rhythm under the context of current recommendations for cardiopulmonary resuscitation.
  
  
  METHODS
  From inception to June 2012, Medline, Embase, and the Cochrane Central Register of Controlled Trials were searched systemically for randomized controlled trials (RCTs) and observational cohort studies that compared the effects of biphasic and monophasic shocks on Vf termination, return of spontaneous circulation (ROSC), and survival to hospital discharge in OHCA patients with initial Vf rhythm. No restrictions were applied regarding language, population, or publication year.
  
  
  RESULTS
  Four RCTs including 572 patients were identified from 131 potentially relevant references for meta-analysis. The synthesis of these RCTs yielded fixed-effect pooled risk ratios (RRs) for biphasic and monophasic waveforms on Vf termination survival to hospital discharge (RR, 1.14; 95% CI, [0.84-1.54]).
  
  
  CONCLUSIONS
  Biphasic waveforms did not seem superior to monophasic ones with respect to Vf termination, ROSC, or survival to hospital discharge in OHCA patients with initial Vf rhythm under the context of current guidelines. However, most trials were conducted in accordance with previous guidelines for cardiopulmonary resuscitation. Therefore, further trials are needed to clarify this issue.
authors.affiliation: Department of Emergency Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Wang
authors.forename: Chien-Hua
authors.initials: CH
authors.lastname: Huang
authors.forename: Wei-Tien
authors.initials: WT
authors.lastname: Chang
authors.forename: Min-Shan
authors.initials: MS
authors.lastname: Tsai
authors.forename: Sot Shih-Hung
authors.initials: SS
authors.lastname: Liu
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Wu
authors.forename: Yi-Chia
authors.initials: YC
authors.lastname: Lee
authors.forename: Zui-Shen
authors.initials: ZS
authors.lastname: Yen
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Fang
authors.forename: Wen-Jone
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D000368:Aged; D047548:Defibrillators; D004554:Electric Countershock / Q000379:methods*; D004632:Emergency Medical Services / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000628:therapy*