Rectilinear biphasic waveform defibrillation of out-of-hospital cardiac arrest.

Objective: The rectilinear biphasic (RLB) waveform has been shown to effectively defibrillate short-duration ventricular fibrillation (VF) at significantly lower energies than a monophasic damped sine (MDS) waveform. This article reports RLB waveform defibrillation effectiveness for patients presenting in VF during out-of-hospital cardiac arrest when compared with historical MDS effectiveness.

Methods: External RLB defibrillators were deployed in the Omaha Fire Department's emergency medical services (EMS) system. The RLB defibrillators delivered an escalating three-shock sequence of 120, 150, and 200 J. The results observed during the first year of full deployment were compared with the results observed during the previous year when only MDS defibrillators were deployed in the system. The MDS defibrillators delivered an escalating three-shock sequence of 200, 300, and 360 J. Defibrillation was defined as termination of VF for at least 5 seconds after a defibrillation shock.

Results: There were 141 adult patients presenting in VF without trauma during the first year using RLB defibrillators. By comparison, there were 153 adult patients during the comparable year using MDS defibrillators. The 120-J RLB shocks had a significantly higher first-shock rate of successful VF termination (67%, 95% CI: 59%-75%) compared with the initial 200-J MDS shocks (48%, 95% CI: 40%-57%, p < 0.0025; odds ratio 2.14 [1.33-3.42]). The number of patients who were defibrillated to a return of spontaneous circulation with a sinus rhythm was significantly greater (25%, 95% CI: 18%-33%) when using the RLB defibrillator compared with using the MDS defibrillator (15%, 95% CI: 10%-22%, p = 0.05; odds ratio 1.85 [1.04-3.31]).

Conclusion: The RLB defibrillator terminated the VF of patients in out-of-hospital cardiac arrest with superior rates using significantly less energy compared with historical rates for a higher-energy MDS defibrillator.