ORIGINAL ARTICLES
Comparison of neurological outcomes following witnessed out-of-hospital ventricular fibrillation defibrillated with either biphasic or monophasic automated external defibrillators
1 Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Japan
2 Kyoto University Health Service, Kyoto, Japan
3 Department of Pediatrics, Sarver Heart Center, The University of Arizona College of Medicine, Tucson, Arizona, USA
4 Center for Medical Education, Kyoto University Graduate School of Medicine, Kyoto, Japan
5 Senri Critical Care Medical Center, Osaka Saiseikai Senri Hospital, Suita, Japan
6 Yukioka Hospital, Osaka, Japan
7 Department of Emergency medicine and Critical Medicine, Juntendo University Urayasu Hospital, Urayasu, Japan
8 Department of Emergency Room Medicine, Kinki University School of Medicine, Osaka-Sayama, Japan
Correspondence to:
Dr K Kajino, Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Japan 5430035; kajihanapu{at}yahoo.co.jp
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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