Your patient is a 54 year old male, who had a witnessed cardiac arrest with immediate bystander CPR. On arrival, you are told they have used an AED and delivered 3 shocks. When you attached your monitor/defibrillator and pause for a rhythm check, you see ventricular fibrillation, so you immediately deliver a shock, and resume CPR. Vascular access is obtained, and the patient is given 1 mg of epi. The airway is being managed; everything is going along like clockwork. 10 minutes into your resuscitation, you have given another 2 mg of epi, as well as a total of 450 mg of amiodarone and a number of defibrillation shocks. And still your patient stubbornly refuses to convert from the initial v-fib rhythm. Now what?
Enter Double Sequential External Defibrillation. This is certainly not a new concept. One of the earliest references I was able to find was an article by D. Hoch et al, published in the Journal of the American College of Cardiology in 1994, which describes “A technique for terminating refractory ventricular fibrillation”. An even earlier article, published in 1986 by Chang et al, referenced the use of double and triple sequential defibrillation in an animal study. Some of the more recent literature available are published case studies involving a small cohort of patients. The majority of the information that I have reviewed indicates an increase in success rate for termination of refractory ventricular fibrillation using DSED (double sequential external defibrillation) over the traditional method using a single defibrillator.
Double Sequential External Defibrillation involves the use of two defibrillators, and a total of four defibrillation electrodes. One set is applied in the standard Anterior/Lateral position, and the second set is applied in the Anterior/Posterior position. The defibrillators are charged, and then the shocks are delivered by a single operator pressing both “shock” buttons at the same time.
There are a number of theories as to why double sequential defibrillation is successful. One of the more widely accepted of these is that by using two defibrillators and four pads, there is an increase in the overall area of myocardium that is affected by the shock. Another is the increase in the length of time that the energy is delivered, as it is difficult to actually press the two shock buttons at exactly the same time. Regardless of which thought process is the true reason for success, the current, albeit limited data suggests that Double Sequential External Defibrillation is a viable treatment modality for recurrent shockable rhythms which do not respond to standard ACLS treatment guidelines.
What we truly need is more data, and the only way to gather it is to integrate DSED into our current treatment guidelines, and then collect and study the outcomes. Currently Toronto EMS has recommended that their paramedics have arrest patients with refractory VF contact medical control for permission to utilize DSED. There are a number of services in the U.S. that have written protocols for the use of DSED. Perhaps soon there will be a proper, large scale, randomized double blind prospective study done on this topic. Until then, ECC guidelines will continue to not recommend for or against the use of DSED for treatment of refractory VF.
Double Sequential Defibrillation is certainly not the “holy grail” treatment to fix everything, but it is another tool, which, when used in the proper context, along with high quality CPR, proper airway management and appropriate resuscitation medications, may lead to a positive outcome for some cardiac arrest patients.
Here is a proposal that I submitted to the Office of the Medical Director, Manitoba Health EMS Branch on the use of Double Sequential External Defibrillation by EMS in Manitoba. Proposal For The Use of DSD for the Treatment of Refractory VF or VT by EMS in Manitoba
If you are planning to attend PACE2017 in Quebec, There will a presentation on case studies of the use of Double Sequential Defibrillation by Martin Johnson ACP, one of the authors noted in the references below.
References:
Hoch DH, McPherson CM , Rosenfeld LE et al. Double sequential external shocks for refractory ventricular fibrillation. Journal of the American College of Cardiology, 1994; 23(5):1141-5 https://doi.org/10.1016/0735-1097(94)90602-5
Chang MS, Inoue H, Kallok MJ, et al. Double and triple sequential shocks reduce ventricular defibrillation threshold in dogs with and without myocardial infarction. Journal of the American College of Cardiology, 1986; 8(6):1393-1405 https://doi.org/10.1016/S0735-1097(86)80313-8
Cabañas JG, Myers JB, Williams JG, et al. Double Sequential External Defibrillation in Out-of-Hospital Refractory Ventricular Fibrillation: A Report of Ten Cases. Prehospital Emergency Care, 2015; 19(1): 126-130 http://dx.doi.org/10.3109/10903127.2014.942476
Johnston M, Cheskes S, Ross G, Verbeek PR Double Sequential External Defibrillation and Survival from Out-of-Hospital Cardiac Arrest: A Case Report, Prehospital Emergency Care, 2016; 20(5); 662-666 http://dx.doi.org/10.3109/10903127.2016.1168891
Erich J Hold the Coroner. EMSWorld.com, October 10, 2011 http://www.emsworld.com/article/10318805/double-sequential-defibrillation