Beyond ACLS: Dual Simultaneous External Defibrillation

Background: Out-of-hospital cardiac arrest (OHCA) occurs in the United States at a rate of nearly 300,000 individuals per year. Even more concerning is the high mortality rate which is associated with this. The majority of OHCA is due to cardiac etiology with the most common initial rhythm being ventricular fibrillation (VF). What we all know is that high-quality, limited interruption cardiopulmonary resuscitation (CPR) and early defibrillation are the hallmarks of successful neurologic outcomes in OHCA. For many who have heard me speak about ACLS, you have heard me say that these guidelines are created for the providers who do not perform resuscitation as part of their daily routine. For those of us in the trenches of the emergency department, we have to think beyond ACLS at times. Although VF typically responds very well to the standard energies of defibrillation, maybe in patients with higher body mass index or morbid obesity we need higher energies to achieve successful defibrillation.

What They Did:

  • Describe a novel approach of “high-energy” defibrillation in a patient with intractable VF after cardiac arrest

How do you perform dual simultaneous external defibrillation?

  • This procedure should only be used in refractory ventricular fibrillation after multiple attempts at defibrillation and appropriate medications have been given
  • Using a second defibrillator, you can place a second set of external defibrillation pads next to each other, but ensure that the pads are not making contact with each other
  • Charge both monitors (360J for monophasic and 200J for biphasic)
  • Ensure everyone is clear of the patient
  • Simultaneously press the shock button on both monitors
  • Immediately resume CPR

Dual Simultaneous Defibrillation

All of the above are acceptable ways to place the pads


  • evidence-pyramidNow I get it, in the scheme of evidence based medicine, case reports are amongst one of the lowest forms of evidence, but hear me out. I am not talking about doing this on every patient with VF. I am talking about the patient who you have tried to defibrillate several times unsuccessfully; I am talking about thinking outside the box. What do you have to lose? The patient is going to die if you are not able to get a perfusing rhythm. So after high quality CPR, multiple rounds of defibrillation, and appropriate medications, if you still have refractory VF, why not just give this a try?
  • Body habitus is an important variable for successful defibrillation. Lets face it; our population is not getting thinner. Obesity is not discussed in ACLS. The amount of tissue that electricity has to get through will affect the amount of effective energy that will be delivered to the fibrillating heart. Although this was a swine model, Zhang Y et al [2] did show that there was an inverse relationship of body mass with successful defibrillation.
  • There is also an older case series in JACC from 1994 [3] that describes 5 patients with cardiomyopathy or Wolff-Parkinson-White (WPW) Syndrome undergoing electrophysiology studies failing to convert out of VF after 7 – 20 shocks with monophasic energies ranging from 200 – 360J. All 5 patients finally converted after getting a double shock with a total of 720J
  • There was also a recent retrospective case series by Cabanas JG et al [4] of 10 cases of refractory VF.  Patients got at least 5 unsuccessful single shocks, epinephrine administration, and a dose of anti arrhythmic medication before double sequential external defibrillation (DSED) was attempted.  VF broke in 7/10 (70%) of cases, only 3/10 (30%) had ROSC in the field, and 0/10 (0%) survived to discharge.

Clinical Take Home Point: Consider using high-energy, dual simultaneous defibrillation in patients with refractory VF only after high quality CPR, several attempts at defibrillation, and appropriate medications have been given.


  1. Leacock BW. Double Simultaneous Defibrillators for Refractory Ventricular Fibrillation. JEM 2014; 46 (4): 472 – 74. PMID: 24462025
  2. Zhang Y et al. Body Weight is a Predictor of Biphasic Shock Success for Low Energy Transthoracic Defibrillation. Resuscitation 2002; 54: 281 – 7. PMID: 12204462
  3. Hoch DH et al. Double Sequential External Shocks for Refractory Ventricular fibrillation. JACC 1994; 23: 1141 – 5. PMID: 8144780
  4. Cabanas JG et al. Double Sequential External Defibrillation in Out-of-Hospital Refractory Ventricular Fibrillation: A Report of Ten Cases. Perhaps Emerg Care 2015; 19 (1): 126 – 130. PMID: 25243771
  5. Merlin MA et al. A Case Series of Double Sequence Defibrillation. Prehospital Emergency Care. 2016 Jan 29:1-4. [epub ahead of print]
  6. Ross EM et al. Dual Defibrillation in Out-Of-hospital Cardiac Arrest: A Retrospective Cohort Analysis. Resuscitation 2016; 106:14-7. PMID: 27344928

For More Thoughts on This Topic Checkout:

Post Peer Reviewed By: Anand Swaminathan (Twitter @EMSwami)

Cite this article as: Salim Rezaie, "Beyond ACLS: Dual Simultaneous External Defibrillation", REBEL EM blog, July 16, 2015. Available at:
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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of REBEL EM

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25 thoughts on “Beyond ACLS: Dual Simultaneous External Defibrillation”

  1. Is there a specific weight that showed this to be a option? And was it attempted for cardioversion in afib?

    • Hello Kate,
      Great questions. For your first question there really isn’t a weight cut off per say. The majority of these cases will be terminated
      within the initial three shocks, but there are cases where patients may remain in VF. Most of the data on this is in swine models and case reports of humans. The results of the swine model were limited by the fact that the study only applied to the low body weight (18 – 41 kg,
      average 26 kg) of the swine model. The majority of the case reports and case series in humans look they were patients with BMI > 35, but this is not an absolute cutoff. As for your second question there have been similar findings in cardioversion of atrial fibrillation (AF) where patients with BMI > 25 had a lower rate of cardioversion at lower energies when compared to patients with a normal BMI. The reference for AF is here:

      Glover BM,Walsh SJ, McCann CJ, et al. Biphasic energy selection for transthoracic cardioversion of atrial fibrillation. The BEST AF Trial. Heart 2008;94:884–7. PMID: 17591649

      Hope this helps.


  2. Thanks for the article. My EMS system currently uses Double Sequential and has for the last 2 years. Our numbers are a bit higher for uses of DSD, around 23, and we have had 2 survive to discharge. As we learn more from our colleagues in the EP lab, and get data from those who are using DSD, my medical director and I, along with a few others are beginning to think it’s more about the direction of the energy vs. the amount. We use an AP and conventional placement of pads instead of a side by side. I spoke to Dr. Peter Kudenchuck (Resucistion academy) about this and he tends to agree, although he is not a believer in this procedure. Good stuff! Thanks!

    • Hey Mike,
      Appreciate your input on your experiences. I do tend to agree…It seems to make more sense about the direction of energy from a physics standpoint. Have you thought about writing up your results so that others could have the benefit of using this information? Cheers and TY again.


    • Hey Mike,

      I was wondering which devices your service uses and if there are any concerns regarding warranty and device malfunction.

      Best regards,


      • Hello Max,
        In the ED I work in we use a Medtronic LifePak 20. You have to remember this is the rare patient that you will attempt this on (i.e. last ditch effort). Obviously this is an off-label use. I have tried this twice now…one time successful, one time not. Never had a device malfunction. Hope this helps.


    • Hey Mike,

      My name is Jamal, I am a student paramedic is the UK and I am looking to do my dissertation on this topic. I am trying to get as much information as possible. It is amazing that you have this in practice in your ambulance service. Would i be able to get any information from yourself ?

  3. Salim, thanks for this fantastic post. Here’s another article recently published that will add to this robust data 🙂

    Merlin MA, Tagore A, Bauter R, Arshad FH. A Case Series of Double Sequence Defibrillation. Prehospital Emergency Care. 2016 Jan 29:1-4.

  4. A question about nomenclature:
    In DSED, “S” should means sequential or simultaneous?

    In theory, it should be simultaneous to get the most energy at the same time. However, most publication avaiable currently choose the term “sequential”……

  5. Would love to see your take on the Ross article in Resus. First negative bit on DSD I have seen. Where do you see it fitting in the evidence base? Is it strong enough to argue against the other articles?

    • Hello Jeff,
      50 cases of refractory VF/Pulseless VT is the biggest cohort I am aware of in this specific population. A few things about the study you are referring to.

      1. Bystander CPR in DSD was 30% vs 45% in the standard defibrillation cohort
      2. Witnessed Arrest in DSD was 38% vs 54.6% in the standard defibrillation cohort
      3. Both one and two are known to increase the chance of survival and neurologically intact survival
      4. Only 26/50 patients met the criteria of refractory VF. Recurrent VF and Refractory VF were included in this data analysis which could dilute the results
      5. Retrospective, Observational study with decision to perform DSD up to the lead paramedic could lead to a huge selection bias of patients
      6. All other data on DSD are case reports and case series, so this retrospective analysis does sit higher in the chain of EBM

      This study had too many biases against DSD including witnessed arrest, bystander CPR and including recurrent VF with refractory VF. I am not sure this study refutes DSD, but instead emphasizes the importance of witnessed arrests and bystander CPR to help improve chances of survival with good neuro outcomes. I think its still OK to try DSD if 3 standard shocks and ACLS meds have not helped.


  6. Dr. Kevin Boehm and I had a successful case of dual axis defibrillation for refractory vfib/electrical storm.
    We used an esmolol bolus and drip in conjunction with 720J. The patient survived to hospital discharge and I still see the patient when he comes to visit after his cardiology follow up. We wrote a case report and had it published in Western Journal of Emergency Medicine. That was my intern year and I am starting my 4th year of residency this July.


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