Biphasic versus monophasic defibrillation in out-of-hospital cardiac arrest: a systematic review and meta-analysis
ABSTRACT 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.
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.
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]).
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.
Resuscitation 06/1998; 37(2):67-80. · 3.96 Impact Factor
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ABSTRACT: Survival after prolonged ventricular fibrillation (VF) appears severely limited by 2 major factors: (1) low defibrillation success rates and (2) persistent post-countershock myocardial dysfunction. Biphasic (BP) waveforms may prove capable of favorably modifying these limitations. However, they have not been rigorously tested against monophasic (MP) waveforms in clinical models of external defibrillation, particularly where rescue from prolonged VF is the general rule. We randomized 26 dogs to external countershocks with either MP or BP waveforms. Hemodynamics were assessed after shocks applied during sinus rhythm, after brief VF (>10 seconds), and after resuscitation from prolonged VF (>10 minutes). Short-term differences in percent change in left ventricular +dP/dt(max) (MP -16+/-28%, BP +9.1+/-24%; P=0.03) and left ventricular -dP/dt(max) (MP -37+/-26%, BP -18+/-20%; P=0.05) were present after rescue from brief VF, with BP animals exhibiting less countershock-induced dysfunction. After prolonged VF, the BP group had lower mean defibrillation thresholds (107+/-57 versus 172+/-88 J for MP, P=0.04) and significantly shorter resuscitation times (397+/-73.7 versus 488+/-74.3 seconds for MP, P=0.03). External defibrillation is more efficacious with BP countershocks than with MP countershocks. The lower defibrillation thresholds and shorter resuscitation times associated with BP waveform defibrillation may improve survival after prolonged VF arrest.Circulation 06/2000; 101(25):2968-74. DOI:10.1161/01.CIR.101.25.2968 · 14.95 Impact Factor
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ABSTRACT: In the present study, we compared an automatic external defibrillator (AED) that delivers 150-J biphasic shocks with traditional high-energy (200- to 360-J) monophasic AEDs. AEDs were prospectively randomized according to defibrillation waveform on a daily basis in 4 emergency medical services systems. Defibrillation efficacy, survival to hospital admission and discharge, return of spontaneous circulation, and neurological status at discharge (cerebral performance category) were compared. Of 338 patients with out-of-hospital cardiac arrest, 115 had a cardiac etiology, presented with ventricular fibrillation, and were shocked with an AED. The time from the emergency call to the first shock was 8.9+/-3.0 (mean+/-SD) minutes. The 150-J biphasic waveform defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation. Although survival rates to hospital admission and discharge did not differ, discharged patients who had been resuscitated with biphasic shocks were more likely to have good cerebral performance.Circulation 11/2000; 102(15):1780-7. DOI:10.1161/01.CIR.102.15.1780 · 14.95 Impact Factor