Comparison of Conventional Defibrillation (CDF) with Double Sequential External Defibrillation (DSDF) in achieving Return Of Spontaneous Circulation (ROSC) in Refractory Ventricular Fibrillation(VF) and pulseless Ventricular Tachycardia (pVT)

Background:

Factors affecting defibrillation success is proportional to the transthoracic impedance, which decreases with recurrent shock, apart from more success with higher energies and vector change. Double Sequential External Defibrillation (DSDF) is delivery of two defibrillating currents from two separate defibrillator devices, to be administered one after another as close as possible, with a small deliberate pause. The first current lowers the defibrillation threshold of the myocardium and increases the success rate of the subsequent transthoracic current. Also, the number of vectors via which the current reaches the myocardium increases as well as the energy delivered, and thus the defibrillation success.

Review of Literature:

Lower energies for successful defibrillation with the use of sequential pulse defibrillation with the use of epicardial electrodes, were demonstrated in volunteer patients of WPW syndrome undergoing accessory pathway ablation.(1) However, a systematic review for use of DSDF for refractor ventricular fibrillation cardiac arrest failed to show improved outcomes in OHCA.(2) Recently published Dose-VF trial found a higher rates of VF termination (66.6% in CDF and 76.3% in DSDF) and ROSC (25% vs 40%) with the use of DSDF in OHCA patients.(3)

Aim: To compare the efficacy of CDF with DSDF in achieving ROSC among patients with refractory VF and pulseless Ventricular Tachycardia (pVT)

Study Design: Prospective, open label, multi Centre RCT in India

Inclusion Criteria: All adult patients with refractory VF and pVT as defined by VF / pVT persisting after administration of three consecutive shocks delivered as per current ACLS recommendations

Exclusion Criteria: Patients with AICD

                            Spine Trauma

                           Traumatic Cardiac arrest

                           Pregnancy

                           DNR status

Study method-

Cohort: Patients presenting with either Out of Hospital Cardiac Arrest (OHCA) or having In Hospital Cardiac Arrest (IHCA) – with refractory VF and pVT

Cohort 1: IHCA – Two arms CDF and DSDF

Cohort 2 OHCA – Two arms CDF and DSDF

Randomization: Block randomization – treatment sequence will be generated for each centre participating prior to the start of the study.

All included patients will be given initial resuscitation as per the current AHA guidelines – which includes high quality CPR and defibrillation via antero-lateral pad placement and administration of emergency drugs, with or without use of advanced airway.

After the third failed attempt at defibrillation, the patient will be allocated to either the control group or intervention group.

Control group: CDF – All subsequent defibrillation attempts will continue with the same placement of pads.

Intervention group: DSDF – A second set of defibrillation pads will be applied in antero-posterior position with minimal interruption in CPR. All subsequent defibrillation will be done by sequential shocks delivered with a short interval (less than 1 second) between the two shocks – by a single operator pressing the shock button in rapid succession

Outcome measures:

Primary Outcome: To compare achievement of ROSC between CDF and DSDF in refractory VF/pVT

Secondary Outcome: Survival to hospital discharge

                        Absence of VF / pVT on subsequent rhythm analysis after defibrillation and a 2-minute interval of CPR

                         VF / pVT recurrence within 24 hrs

                        a good neurologic outcome at hospital discharge, defined as modified Rankin scale score of 2 or lower

References:

1-     Jones DL, Klein GJ, Guiraudon GM, Sharma AD. Sequential pulse defibrillation in humans: orthogonal sequential pulse defibrillation with epicardial electrodes. J Am Coll Cardiol. 1988;11(3):590–596. doi: 10.1016/0735-1097(88)91536-7.

2-     Deakin CD, Morley P, Soar J, Drennan IR. Double sequential defibrillation for refractory ventricular fibrillation cardiac arrest: a systematic review. Resuscitation. 2020;155:24–31

3-     Cheskes S, Dorian P, Feldman M, McLeod S, Scales DC, Pinto R, Turner L, Morrison LJ, Drennan IR, Verbeek PR. Double sequential external defibrillation for refractory ventricular fibrillation: The DOSE VF pilot randomized controlled trial. Resuscitation. 2020 May;150:178-184. doi: 10.1016/j.resuscitation.2020.02.010. Epub 2020 Feb 19. PMID: 32084567.