UMEM Educational Pearls

DOSE VF (DOuble SEquential External Defibrillation for Refractory VF) Trial 

Background - High quality data regarding the use of double sequential external defibrillation (DSED) and vector-change (VC) defibrillation in refractory vfib is limited


-Three-group, cluster-randomized, controlled trial in six Canadian paramedic services

-Study population: 

-OHCA with refractory vfib (initial presenting rhythm of vfib or pulseless VT that was still present after three consecutive rhythm analyses and standard defibrillations separated by 2 minute intervals of CPR) of presumed cardiac etiology (405 patients)

-Some notable exclusion criteria: 

-suspected drug overdose, hypothermia, traumatic cardiac arrest


-First 3 defib attempts in the standard (anterior-lateral) position

-If remained in vfib after three consecutive shocks randomized to one of:

1. Standard defib for all subsequent attempts (136 pts)

2. VC defib (all subsequent attempts in anterior-posterior position) (144 pts)

3. DSED (applied second set of pads in AP position) with near simultaneously (<1 sec) defib shocks (125 pts)


-Primary outcome: survival to hospital discharge

-38 patients (30.4%) in the DSED group vs. 18 (13.3%) in the standard group (RR 2.21; 95% CI, 1.33 to 3.67) (Fragility index of 9)

-31 patients (21.7%)  in the VC group (RR [vs. standard], 1.71; 95% CI, 1.01 to 2.88) (Fragility index of 1)

-Notable secondary outcome: survival with a good neurologic outcome

-34 patients (27.4%) who received DSED vs. 15 patients (11.2%)  with standard defibrillation (RR, 2.21; 95% CI, 1.26 to 3.88)



-68% of arrests witnessed, 58% received bystander CPR, median response time of 7.4-7.8 min

-Did not reach planned sample size 2/2 COVID pandemic

-No reporting of post-arrest care (e.g. TTM, PCI)

-Overall rates of survival and good neuro outcome on the higher side even with standard of care

-More/larger studies needed, but can consider DSED for refractory vfib, particularly if you are in a setting without more advanced circulatory support/resources




Cheskes S, Verbeek PR, Drennan IR, et al. Defibrillation strategies for refractory ventricular fibrillation. N Engl J Med. Published online November 6, 2022:NEJMoa2207304.