Dual sequential defibrillation (DSD) continues to be adopted into clinical practice without any evidence to support its benefits and certainly some suggestion that it may do more harm than good. Does the latest evidence from Cheskes and his research team provide evidence that we should be looking to introduce this technique of last resort?
Approximately 20% of cardiac arrests initially present in a shockable rhythm; usually ventricular fibrillation (VF). Of these, about 20% will remain in VF after 5 shocks, despite standard resuscitation interventions.3 Not surprisingly, patients in refractory VF have significantly lower rates of survival than patients who respond to standard resuscitation treatments and it is a clinical priority to terminate VF as soon as possible.
Dual sequential defibrillation was introduced on the premise that ‘more must be better’ and was initially spurred on by a number of case reports that represent no more than publication bias. The term ‘dual (or double) sequential defibrillation’ refers to a non-standardised technique that has a number of important variations in how it is delivered. In most cases, the initial defibrillation pads are placed in a standard antero-lateral position, according to current guidelines.4 The second pair is either placed alongside the first, or in an antero-posterior position. The technique of shock delivery also varies between cases. In initial case reports, both defibrillators were discharged at exactly the same time, potentially resulting in overlapping waveforms. This has resulted in at least one case where one defibrillator has been damaged by its counterpart and more recent studies, including that by Cheskes et al. have deliberately introduced a short manual pause between discharge of each defibrillator.