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Comparison of neurological outcomes following witnessed out-of-hospital ventricular fibrillation defibrillated with either biphasic or monophasic automated external defibrillators
  1. K Kajino1,
  2. T Iwami2,
  3. R A Berg3,
  4. A Hiraide4,
  5. Y Hayashi5,
  6. H Yukioka6,
  7. H Tanaka7,
  8. T Shimazu8,
  9. H Sugimoto1
  1. 1
    Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Japan
  2. 2
    Kyoto University Health Service, Kyoto, Japan
  3. 3
    Department of Pediatrics, Sarver Heart Center, The University of Arizona College of Medicine, Tucson, Arizona, USA
  4. 4
    Center for Medical Education, Kyoto University Graduate School of Medicine, Kyoto, Japan
  5. 5
    Senri Critical Care Medical Center, Osaka Saiseikai Senri Hospital, Suita, Japan
  6. 6
    Yukioka Hospital, Osaka, Japan
  7. 7
    Department of Emergency medicine and Critical Medicine, Juntendo University Urayasu Hospital, Urayasu, Japan
  8. 8
    Department of Emergency Room Medicine, Kinki University School of Medicine, Osaka-Sayama, Japan
  1. Dr K Kajino, Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Japan 5430035; kajihanapu{at}


Background: Biphasic waveform defibrillation results in higher rates of termination of fibrillation than monophasic waveform defibrillation but has not been shown to improve survival outcomes.

Objective: To compare the effectiveness of a biphasic automated external defibrillator (AED) with a monophasic AED for witnessed out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF).

Methods: In a prospective population-based cohort study, adults with witnessed VF OHCA were treated with either monophasic or biphasic waveform AED shocks. The primary outcome measure was neurologically favourable 1-month survival, defined as a Cerebral Performance Categories score of 1 or 2.

Results: Of 366 adults with witnessed OHCA of presumed cardiac aetiology, 74 (20%) had VF. Termination of VF with the first shock tended to occur more frequently after biphasic AED shocks (36/44 (82%) vs 20/30 (67%), p = 0.14). Return of spontaneous circulation (ROSC) occurred more frequently after biphasic AED shocks (29/44 (66%) vs 8/30 (27%), p = 0.001). Neurologically favourable 1-month survival was also more frequent in the biphasic group (10/44 (23%) vs 1/30 (3%), p = 0.04). The median time interval from the first shock to the second shock was 67 s in the monophasic group and 24 s in the biphasic group (p = 0.001).

Conclusions: Treatment with biphasic AED shocks improved the likelihood of ROSC and neurologically favourable 1-month survival after witnessed VF compared with monophasic AED shocks. In addition to waveform differences, a shorter time interval from the first shock to the second shock could account for the better outcomes with biphasic AED.

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  • Funding: This study was supported by Grant-in-Aid for University and Society Collaboration, Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture, Japan (No 11794023, 19390459) and Health and Labor Science Research Grant for Cardiovascular Diseases (14C-7), H16-Shinkin-02, Comprehensive Research on Cardiovascular Diseases, and Research on Medical Safety and Health Technology Assessment from the Japanese Ministry of Health, Labor and Welfare.

  • Competing interests: None.

  • Ethics approval: The research was approved by the institutional review board of Osaka University with the assent of the EMS authorities and local governments in Osaka prefecture.

  • The primary authors had full access to and take responsibility for the integrity of the data. All authors have read and agreed the manuscript as written.

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