What is the role of double sequential defibrillation in treating refractory ventricular fibrillation or pulseless ventricular tachycardia?

Role of Double Sequential Defibrillation in Refractory Ventricular Fibrillation

Double sequential defibrillation (DSED) may be considered for adults with cardiac arrest who remain in ventricular fibrillation or pulseless ventricular tachycardia after ≥3 consecutive standard defibrillation attempts, based on the 2023 ILCOR guidelines showing improved survival and functional outcomes compared to standard defibrillation. 1

Current Evidence and Guideline Recommendations

The 2023 International Liaison Committee on Resuscitation (ILCOR) guidelines represent a significant shift from the 2020 recommendation that suggested against routine use of DSED. 1 This change was driven by a single randomized controlled trial of 261 out-of-hospital cardiac arrest patients that demonstrated:

• Improved functional outcome (modified Rankin Scale 0-2): 27.4% with DSED versus 11.2% with standard defibrillation (adjusted RR 2.21,95% CI 1.26-3.88) 1
• Improved survival to hospital discharge: 30.4% with DSED versus 13.3% with standard defibrillation (adjusted RR 2.21,95% CI 1.33-3.67) 1

However, the evidence remains low-certainty, downgraded for risk of bias and imprecision, resulting in only a weak recommendation. 1

When to Consider DSED

Specific Criteria for Implementation

DSED should be considered specifically for:

• Adults with cardiac arrest remaining in VF or pulseless VT after ≥3 consecutive standard defibrillation attempts 1
• Patients representing approximately 20% of VF/pulseless VT cases who develop refractory shockable rhythms 1

Critical Prerequisites Before DSED

Before progressing to DSED, ensure:

• Correct pad placement for standard defibrillation has been verified (one pad below right clavicle just right of upper sternal border, other in left midaxillary line) 1
• Adequate pad-skin contact to optimize energy delivery 1
• High-quality CPR is being maintained throughout 2

Technical Implementation

Recommended Technique

If DSED is used, employ a single operator activating two defibrillators in sequence (good practice statement). 1 This approach mirrors the methodology used in the available trial evidence.

The technique involves:

• Two defibrillators with separate pairs of electrodes 3
• Sequential shock delivery (not simultaneous) 1
• One defibrillator with standard anterolateral pad placement 1
• Second defibrillator with either anteroposterior or additional anterolateral placement 1

Alternative Strategy: Vector Change Defibrillation

Vector change (VC) defibrillation represents an alternative approach with very low-certainty evidence:

• No significant improvement in favorable functional survival (16.2% vs 11.2%, aRR 1.48,95% CI 0.81-2.71) 1
• Improved survival to hospital discharge (21.7% vs 13.3%, aRR 2.21,95% CI 1.01-2.88) 1
• Higher VF termination rate (79.9% vs 67.6%, aRR 1.18,95% CI 1.03-1.36) 1

Current evidence does not permit distinguishing whether DSED or VC defibrillation is superior to the other. 1

Important Caveats and Limitations

Resource Considerations

DSED requires availability of two defibrillators, which has significant resource implications:

• Some EMS systems already use DSED and may easily implement this practice 1
• Other systems would require substantial new resource allocation for additional defibrillators or ambulances 1
• The task force acknowledged such resource allocation may not be justified based on a single relatively small study 1

Clinical Recognition Challenges

The difference between truly refractory VF (failure to terminate) and recurrent VF (recurring after successful defibrillation) may not be recognized clinically. 1 This distinction is important because:

• Refractory VF may benefit more from electrical therapies like DSED 1
• Recurrent VF may require different pharmacological or other interventions 1
• Future "see-through CPR" algorithms may help distinguish these patterns 1

Evidence Quality Issues

The recommendation is based on:

• A single RCT with 261 patients (low-certainty evidence for DSED) 1
• No randomized controlled trials identified in systematic reviews prior to 2023 4, 5
• Previous observational studies had critical or serious risk of bias due to confounding 1
• Very high heterogeneity preventing meta-analysis in earlier systematic reviews 5

Integration into Resuscitation Algorithm

Standard Approach First

1. Deliver initial defibrillation at manufacturer-recommended energy for biphasic defibrillators or 360J for monophasic 2
2. Resume high-quality CPR immediately for 2 minutes after each shock 2
3. Administer epinephrine after initial defibrillation attempts fail (1 mg IV/IO every 3-5 minutes) 2
4. Consider antiarrhythmics (amiodarone 300 mg first dose, 150 mg second dose, or lidocaine 1-1.5 mg/kg) 2

Progression to DSED

1. After ≥3 consecutive failed standard defibrillation attempts, consider DSED or VC defibrillation 1
2. Ensure two defibrillators are available and properly positioned 1
3. Have single operator coordinate sequential activation 1
4. Continue high-quality CPR between attempts 2

Practical Clinical Considerations

Do not delay standard resuscitation efforts to set up DSED if resources are not immediately available. 2 The foundation of cardiac arrest management remains:

• High-quality CPR with adequate compression depth (5-6 cm) and rate (100-120/min) 2
• Early standard defibrillation 2
• Appropriate medication administration 2
• Treatment of reversible causes 2

DSED represents a rescue strategy for the subset of patients who fail standard therapy, not a first-line intervention. 1 The weak recommendation and low-certainty evidence mean this should be implemented thoughtfully within systems that have the resources and training to do so safely.