Comparison of Outcomes After Use of Biphasic or Monophasic Defibrillators Among Out-of-Hospital Cardiac Arrest Patients

Abstract

Background— The use and popularity of the biphasic waveform defibrillator as a replacement for the monophasic waveform defibrillator are increasing, but it is unclear whether this can improve the rate of survival among out-of-hospital cardiac arrest patients. This study aimed to verify the hypothesis that the outcome of out-of-hospital cardiac arrest patients who received defibrillation shock with the biphasic waveform defibrillator was better than that of patients who received defibrillation shock with the monophasic defibrillator. Methods and Results— This prospective, nationwide, population-based, observational study included 21 172 out-of-hospital cardiac arrest patients with initial ventricular fibrillation or pulseless ventricular tachycardia from January 1, 2005, through December 31, 2007. Defibrillation shock was performed by monophasic defibrillator on 8224 (39%) patients and by biphasic defibrillator on 12 948 (61%) patients. The rate of survival at 1 month with minimal neurological impairment was 11.6% (951/8192) in the monophasic defibrillator group and 12.8% (1653/12 928) in the biphasic defibrillator group. Hierarchical logistic regression analysis using a generalized estimation equation showed no significant difference between the biphasic and monophasic groups in 1-month survival with minimal neurological impairment (adjusted odds ratio, 1.07; 95% confidence interval, 0.91–1.26; P =0.42). Confirmatory propensity score analyses showed similar results. Conclusions— Although monophasic defibrillators are being replaced by biphasic defibrillators, our nationwide population-based observational study failed to demonstrate a statistically significant association between defibrillation waveform and 1-month survival rate with minimal neurological impairment.

System for open-chest, multidirectional electrical defibrillation

“…Although several authors have reported greater efficiency of biphasic shocks (Shelton et al, 2011;Tanabe et al, 2012), the defibrillatory monophasic truncated exponential waveform was chosen in present study to better isolate the influence of stimulation direction by removing possible interference of waveformdependent effects on myocardial polarization (Trayanova and Bray, 1997). The delivered discharges in the two defibrillation modalities, and at the 3 defibrillator outputs during multidirectional stimulation, reached the same peak voltage and had similar time course at a given energy level, which eliminated a possible bias caused by variation in the pattern of stimulation in different directions and/or modalities introduced by the use of different equipments for each pathway.…”

System for open-chest, multidirectional electrical defibrillation

“…Although several authors have reported greater efficiency of biphasic shocks (Shelton et al, 2011;Tanabe et al, 2012), the defibrillatory monophasic truncated exponential waveform was chosen in present study to better isolate the influence of stimulation direction by removing possible interference of waveformdependent effects on myocardial polarization (Trayanova and Bray, 1997). The delivered discharges in the two defibrillation modalities, and at the 3 defibrillator outputs during multidirectional stimulation, reached the same peak voltage and had similar time course at a given energy level, which eliminated a possible bias caused by variation in the pattern of stimulation in different directions and/or modalities introduced by the use of different equipments for each pathway.…”

Monophasic versus biphasic defibrillation for pediatric out-of-hospital cardiac arrest patients: a nationwide population-based study in Japan

“…Regarding human studies, previous studies with adult patients reported that biphasic waveform shock was superior to monophasic waveform shock in terms of safety under controlled laboratory and in-hospital conditions [6,8,9]. Regarding long-term outcomes, no significant difference was detected between the two types of waveform for defibrillation in any observational studies or in four randomized trials for adults [30-34]. In pediatric patients, no studies compared biphasic and monophasic waveforms, even in controlled laboratory or in-hospital settings.…”

Rapidly switching multidirectional defibrillation: Reversal of ventricular fibrillation with lower energy shocks

“…In addition, we used monophasic defibrillation shocks, whereas the most recent guidelines on resuscitation recommend biphasic shocks because of their reportedly greater efficiency, 29 although some studies have failed to find a significant influence of the waveform on the outcome of patients. 30,31 Monophasic stimuli were chosen in this study because they allow determining the actual effect of multidirectional stimulation in the absence of possible confounding effects associated with the biphasic waveform, which may be clarified in future studies. Moreover, monophasic defibrillatory shocks are still frequently used in clinical practice.…”

System for open-chest, multidirectional electrical defibrillation

“…Although several authors have reported greater efficiency of biphasic shocks (Shelton et al, 2011;Tanabe et al, 2012), the defibrillatory monophasic truncated exponential waveform was chosen in present study to better isolate the influence of stimulation direction by removing possible interference of waveformdependent effects on myocardial polarization (Trayanova and Bray, 1997). The delivered discharges in the two defibrillation modalities, and at the 3 defibrillator outputs during multidirectional stimulation, reached the same peak voltage and had similar time course at a given energy level, which eliminated a possible bias caused by variation in the pattern of stimulation in different directions and/or modalities introduced by the use of different equipments for each pathway.…”

Monophasic versus biphasic defibrillation for pediatric out-of-hospital cardiac arrest patients: a nationwide population-based study in Japan

“…Regarding human studies, previous studies with adult patients reported that biphasic waveform shock was superior to monophasic waveform shock in terms of safety under controlled laboratory and in-hospital conditions [6,8,9]. Regarding long-term outcomes, no significant difference was detected between the two types of waveform for defibrillation in any observational studies or in four randomized trials for adults [30-34]. In pediatric patients, no studies compared biphasic and monophasic waveforms, even in controlled laboratory or in-hospital settings.…”

Rapidly switching multidirectional defibrillation: Reversal of ventricular fibrillation with lower energy shocks

“…In addition, we used monophasic defibrillation shocks, whereas the most recent guidelines on resuscitation recommend biphasic shocks because of their reportedly greater efficiency, 29 although some studies have failed to find a significant influence of the waveform on the outcome of patients. 30,31 Monophasic stimuli were chosen in this study because they allow determining the actual effect of multidirectional stimulation in the absence of possible confounding effects associated with the biphasic waveform, which may be clarified in future studies. Moreover, monophasic defibrillatory shocks are still frequently used in clinical practice.…”

System for open-chest, multidirectional electrical defibrillation

“…Although several authors have reported greater efficiency of biphasic shocks (Shelton et al, 2011;Tanabe et al, 2012), the defibrillatory monophasic truncated exponential waveform was chosen in present study to better isolate the influence of stimulation direction by removing possible interference of waveformdependent effects on myocardial polarization (Trayanova and Bray, 1997). The delivered discharges in the two defibrillation modalities, and at the 3 defibrillator outputs during multidirectional stimulation, reached the same peak voltage and had similar time course at a given energy level, which eliminated a possible bias caused by variation in the pattern of stimulation in different directions and/or modalities introduced by the use of different equipments for each pathway.…”

Monophasic versus biphasic defibrillation for pediatric out-of-hospital cardiac arrest patients: a nationwide population-based study in Japan

“…Regarding human studies, previous studies with adult patients reported that biphasic waveform shock was superior to monophasic waveform shock in terms of safety under controlled laboratory and in-hospital conditions [6,8,9]. Regarding long-term outcomes, no significant difference was detected between the two types of waveform for defibrillation in any observational studies or in four randomized trials for adults [30-34]. In pediatric patients, no studies compared biphasic and monophasic waveforms, even in controlled laboratory or in-hospital settings.…”

Rapidly switching multidirectional defibrillation: Reversal of ventricular fibrillation with lower energy shocks

“…In addition, we used monophasic defibrillation shocks, whereas the most recent guidelines on resuscitation recommend biphasic shocks because of their reportedly greater efficiency, 29 although some studies have failed to find a significant influence of the waveform on the outcome of patients. 30,31 Monophasic stimuli were chosen in this study because they allow determining the actual effect of multidirectional stimulation in the absence of possible confounding effects associated with the biphasic waveform, which may be clarified in future studies. Moreover, monophasic defibrillatory shocks are still frequently used in clinical practice.…”