Comparison of neurological outcomes following witnessed out-of-hospital ventricular fibrillation defibrillated with either biphasic or monophasic automated external defibrillators. Issue 7 (22nd June 2009)

• Record Type: Journal Article
• Authors: Kajino, K; Iwami, T; Berg, R A; Hiraide, A; Hayashi, Y; Yukioka, H; Tanaka, H; Shimazu, T; Sugimoto, H
• Is Part Of: Emergency medicine journal. Volume 26:Issue 7(2009)
• Page Start: 492
• Page End: 496
• Publication Date: 2009-06-22
• Subjects: Emergency medicine -- Periodicals; 616.02505
• DOI: 10.1136/emj.2008.059865
• Languages: English
• ISSNs: 1472-0205

Abstract

Abstract : 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.