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Defibrillation Strategies for VF/pVT

Question Type:
Intervention
Full Question:
Among adults who are in VF or pVT in any setting  (P), does any specific defibrilation strategy (eg 1. energy dose, or 2.shock waveform) (I), compared with standard management (or other defibrilation strategy)  (C), change  (O)?
Consensus on Science:
Biphasic Waveform No new randomized trials of biphasic waveforms since 2010 were identified. Pulsed Biphasic Waveform For the critical outcome of survival to hospital discharge, very-low-quality evidence (downgraded for very serious risk of bias and serious indirectness) from 1 cohort study (ie, no control group)(Didon 2008, 350) with a total of 104 patients that used a 130 J-130 J-180 J pulsed biphasic waveform protocol documented a survival rate of 9.8%. This compares with a weighted average BTE survival rate of 33.1% at 150 to 200 J.(Didon 2008, 350) For the important outcome of termination of fibrillation, the same very-low-quality evidence (downgraded for very serious risk of bias and serious indirectness) from 1 cohort study(Didon 2008, 350) with a total of 104 patients documented first-shock termination rates at 130 J of 90.4% with a pulsed biphasic waveform, comparable with BTE waveforms (weighted average 91.8%) at 150 to 200 J.(Didon 2008, 350) First-Shock Energy For the important outcome of termination of VF/pVT, low-quality evidence (downgraded for imprecision and risk of bias, respectively) from a post hoc report from an RCT and a cohort study showed a first-shock success rate of 73 of 86 (85%) and 79 of 90 (87.8%), respectively, when using a 120 J initial shock with an RLB waveform.(Hess 2011, 685; Morrison 2013, 1480) Single Shock Versus Stacked Shocks For the critical outcome of survival to 1 year, we have identified low-quality evidence (downgraded for serious risk of bias and serious indirectness) from 1 RCT enrolling 845 OHCA patients showing no difference in single versus 3 stacked shocks (odds ratio [OR], 1.64; 95% confidence interval [CI], 0.53–5.06).(Jost 2010, 1614) For the critical outcome of survival to hospital discharge, we have identified low-quality evidence (downgraded for serious risk of bias and serious indirectness) from 1 RCT enrolling 845 OHCA patients showing no difference in single versus 3 stacked shocks (OR, 1.29; 95% CI, 0.85–1.96).(Jost 2010, 1614) For the critical outcome of survival to hospital admission, we have identified very-low-quality evidence (downgraded for serious risk of bias and serious indirectness) from 1 RCT enrolling 845 OHCA patients showing no difference in single versus 3 stacked shocks (OR, 1.02; 95% CI, 0.78–1.34).(Jost 2010, 1614) For the critical outcome of ROSC, we have identified low-quality evidence (downgraded for serious risk of bias and serious indirectness) from 1 RCT enrolling 845 OHCA patients showing no difference in single versus 3 stacked shocks (OR, 0.94; 95% CI, 0.72–1.23).(Jost 2010, 1614) For the important outcome of recurrence of VF (refibrillation), we have identified low-quality evidence (downgraded for serious risk of bias, serious indirectness, and serious imprecision) from 1 RCT enrolling 136 OHCA patients showing no difference in single versus 3 stacked shocks (OR, 1.00; 95% CI, 0.47–2.13).(Berdowski 2010, 72) Fixed Versus Escalating Defibrillation Energy Levels For the critical outcome of survival with favorable neurologic outcome at hospital discharge, we identified very-low-quality evidence (downgraded for serious risk of bias, serious imprecision, and serious indirectness) from 1 RCT enrolling 221 OHCA patients showing no benefit of one strategy over the other (OR, 0.78; 95% CI, 0.34–1.78).(Stiell 2007, 1511) For the critical outcome of survival to hospital discharge, we have identified very-low-quality evidence (downgraded for serious risk of bias, serious imprecision, and serious indirectness) from 1 RCT enrolling 221 OHCA patients showing no benefit of one strategy over the other (OR, 1.06; 95% CI, 0.52–2.16).(Stiell 2007, 1511) For the critical outcome of ROSC, we have identified very-low-quality evidence (downgraded for serious risk of bias, serious imprecision, and serious indirectness) from 1 RCT enrolling 221 OHCA patients showing no benefit of one strategy over the other (OR, 1.095; 95% CI, 0.65–1.86).(Stiell 2007, 1511) Recurrent VF (Refibrillation) For the important outcome of termination of refibrillation, low-quality evidence (downgraded for serious risk of bias) from 2 observational studies(Hess 2008, 28-33; Hess 2011, 685) with a total of 191 cases of initial fibrillation that showed termination rates of subsequent refibrillation were unchanged when using fixed 120 or 150 J shocks, respectively, and another observational study(Koster 2008, 252) (downgraded for confounding factors) with a total of 467 cases of initial fibrillation that showed termination rates of refibrillation declined when using repeated 200 J shocks, unless an increased energy level (360 J) was selected.
Treatment Recommendation:
Biphasic Waveform We recommend that a biphasic waveform (biphasic truncated exponential [BTE] or rectilinear-biphasic [RLB]) is used for both atrial and ventricular arrhythmias in preference to a monophasic waveform (strong recommendation, very-low-quality evidence). In the absence of biphasic defibrillators, monophasic defibrillators are acceptable. Values, Preferences and, Task Force Insights In making this strong recommendation, we place a high value on the reported higher first-shock success rate for termination of fibrillation with a biphasic waveform, the potential for less postshock myocardial dysfunction, and the existing 2010 CoSTR.(Jacobs 2010, S325; Sunde 2010, e71) The task force acknowledges that many emergency medical services (EMS) systems and hospitals around the world continue to use older monophasic devices. Pulsed Biphasic Waveform We recommend following the manufacturer’s instructions for first and subsequent shock energy levels for the pulsed biphasic waveform (strong recommendation, very-low-quality evidence). Values, Preferences, and Task Force Insights In making this strong recommendation, we have placed a high value on following the manufacturer’s guidance in the absence of high-quality data to suggest otherwise. The available very-low-quality data showing the efficacy of a non–impedance compensated pulsed biphasic waveform do not enable direct comparison with other biphasic waveforms. In addition, no clinical studies attest to the efficacy of this waveform in its current impedance-compensated form. First-Shock Energy We recommend an initial biphasic shock energy of 150 J or greater for BTE waveforms, and 120 J or greater for RLB waveforms (strong recommendation, very-low-quality evidence). If a monophasic defibrillator is used, we recommend an initial monophasic shock energy of 360 J (strong recommendation, very-low-quality evidence). Values, Preferences, and Task Force Insights In making these strong recommendations, the working group was keen to acknowledge manufacturer’s instructions and recognize that evidence for the optimal first-shock energy level was lacking. We also considered that although monophasic defibrillators are no longer manufactured, they are still used in many countries. Single Shock Versus Stacked Shocks We recommend a single-shock strategy when defibrillation is required (strong recommendation, low-quality evidence). Values, Preferences, and Task Force Insights In making this strong recommendation, the task force has placed a greater value on not changing current practice and minimizing interruptions in chest compressions whilst acknowledging that studies since 2010 have not shown that any specific shock strategy is of benefit for any survival end point. There is no conclusive evidence that a single-shock strategy is of benefit for ROSC or recurrence of VF compared with 3 stacked shocks, but in view of the evidence suggesting that outcome is improved by minimizing interruptions to chest compressions, we continue to recommend single shocks. The task force is aware that there are some circumstances (eg, witnessed, monitored VF cardiac arrest with defibrillator immediately available) when 3 rapid stacked shocks could be considered. Fixed Versus Escalating Defibrillation Energy Levels We suggest if the first shock is not successful and the defibrillator is capable of delivering shocks of higher energy, it is reasonable to increase the energy for subsequent shocks (weak recommendation, very-low-quality evidence). Values, Preferences, and Task Force Insights In making this recommendation, we have considered that an escalating shock energy may prevent the risk of refibrillation (see ALS 470). We also consider this to be in line with current practices where rescuers will escalate shock energy if initial defibrillation attempts fail and the defibrillator is capable of delivering a higher shock energy. Recurrent VF (Refibrillation) We suggest an escalating defibrillation energy protocol to prevent refibrillation (weak recommendation, low-quality evidence). Values, Preferences, and Task Force Insights In making this weak recommendation, we considered the lack of studies showing myocardial injury from biphasic waveforms, making it reasonable to consider increasing defibrillation energy levels when delivering shocks for refibrillation if the energy dose delivered by the defibrillator can be increased. It is unclear from current studies whether repeated episodes of VF are more resistant to defibrillation and require a higher energy level or whether a fixed energy level is adequate.

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