EMS Today 2019 Quick Take: A prehospital approach to refractory ventricular fibrillation

Exploring unique prehospital approaches to RVF treatment, including double sequential defibrillation, sympathetic blockade and ECMO

NATIONAL HARBOR, Maryland — Refractory ventricular fibrillation is a unique clinical entity requiring alternative treatment techniques. Eric Cortez, M.D., clinical assistant professor of Emergency Medicine at Ohio Health Doctors Hospital presented a session entitled, “A Prehospital Approach to Refractory Ventricular Fibrillation,” at EMS Today. Cortez discussed what to do as a prehospital care provider from the time you recognize RVF to when you arrive at the hospital once you’ve exhausted your typical tools.

Top quotes on refractory ventricular fibrillation

Here are some quotes from Cortez that stood out during his presentation.

Eric Cortez, M.D., clinical assistant professor of Emergency Medicine at Ohio Health Doctors Hospital presented a session entitled, “A Prehospital Approach to Refractory Ventricular Fibrillation,” at EMS Today.
Eric Cortez, M.D., clinical assistant professor of Emergency Medicine at Ohio Health Doctors Hospital presented a session entitled, “A Prehospital Approach to Refractory Ventricular Fibrillation,” at EMS Today. (Photo/Courtesy of Eric Cortez)

“The basic fundamentals are the most important.”

“The evidence is evolving. It’s weak now, but we have to do something or the patient has a near 100 percent mortality.”

“Refractory ventricular fibrillation can be considered a STEMI equivalent.”

Top takeaways on refractory ventricular fibrillation treatment

The mortality associated with ventricular fibrillation ranges from 85-97 percent, Cortez reported. Beyond survival, Cortez noted when we measure outcomes, we’re looking for walking out of the hospital neurologically intact, with a cerebral performance category (CPC) score of 1 or 2. 

1. The fundamentals are essential  

Cortez noted sudden cardiac arrest is a huge crisis, but when we’re examining the research, it boils down to three proven interventions:

  1. High-quality compressions
  2. Defibrillation
  3. Optimal post-resuscitation care

These interventions are proven to impact outcomes when performed early (even before EMS arrives). 

2. Double sequential defibrillation can improve outcomes

One approach to treating refractory ventricular fibrillation which has had some success is double sequential defibrillation. Cortez explained the one-two punch approach: two defibrillators, two sets of pads, applying maximum energy to optimize the chances of defibrillating out of v-fib.

Cortez identified three reasons double sequential defibrillation may improve outcomes:

  1. Vector theory. By adding on a second shock, you’re doubling, but also changing the vector to align more directly with the heart
  2. Duration. Delivering two shocks sequentially doubles the time you’re applying the shock
  3. Energy. We deliver pediatric shock based on kilos, yet don’t adjust adult shock per mass. Delivering more energy through double shocks may be more effective

In the last three to four years, four case studies reported good outcomes with double sequential defibrillation: with three-quarters of patients leaving the hospital with a CPC score of 1 or 2. While the strength of evidence is still weak, there’s not much harm to applying this unproven strategy, Cortez noted.

3. Re-examine medical therapy

Cortez raised another question, whether EMS should limit the administration of epinephrine in refractory ventricular fibrillation cases. It’s fine to continue to administer amiodarone or lidocaine, Cortez noted, but when we encounter these unique circumstances, is there an alternative that better facilitates getting patient out of that electrical storm; v-fib, sympathetic tone, v-fib, sympathetic tone cycle that can be so devastating?

If you inadvertently administered epinephrine to a patient, the worst case scenario would be to cause v-fib, v-tach arrest, he pointed out. So why are we using it in these cases? If we believe an electrical storm is the culprit, epi may not be the best choice to treat.

“Why not block those alpha and beta receptors from being stimulated,” Cortez asked. Once you identify refractory ventricular fibrillation, consider administering an alpha beta blocker, like Esmolol, he advised.

“Overall, this data isn’t practice changing, but it causes you to stop and think, should we be performing sympathetic blockade and limit the amount of epinephrine we administer?” Cortez asked.

4. Advanced interventions: ECMO and ECPR

The goals when faced with OHCA are to maintain airway breathing, proper ventilation, support circulation, prevent re-arrest, perform a 12-lead EKG, therapeutic temperature management (hospital setting plus or minus pre-hospital), and transport to a cath lab. Without fixing the underlying causes, this is all just temporizing, Cortez said.

According to typical post-resuscitative care cath lab indications, unfavorable features include:

  • Unwitnessed cardiac arrest
  • Non v-fib
  • No B-CPR
  • pH < 7.2
  • Lactate > 7
  • Age > 85
  • ESRD
  • Non-cardiac cause (e.g., a tox or respiratory arrest case)
  • Over 30 minutes to ROSC
  • Ongoing CPR

However, in RVF cases, the patient is going to have at least the last two contraindications, Cortez noted. To incorporate those patients who are unfavorable clinically into post-resuscitative care guidelines, Cortez offered an alternative treatment model: extracorporeal cardiopulmonary resuscitation (ECPR) using extracorporeal membrane oxygenation (ECMO).

Indications to qualify for ECPR include:

  • < 75 years
  • A shockable rhythm
  • < 5 minutes to resuscitation
  • Witnessed cardiac arrest
  • Likely cardiac etiology
  • No ROSC by 30 minutes

Indications for excluding ECPR include:

  • Severe comorbidities
  • A DNR order
  • Low probability of survival

He noted a 2016 systematic review of ECPR for refractory ventricular fibrillation out of hospital cardiac arrest including 833 patients had an overall survival rate of 22 percent, with good neurological outcomes in 13 percent.

While refractory ventricular fibrillation is relatively rare, consider implementing double sequential defibrillation and sympathetic blockade in your practice, as well as destinations with advanced interventional capabilities when you encounter RVF.

Additional resources on OHCA ROSC

Learn more about out of hospital cardiac arrest interventions with these articles from EMS1:

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