Resident Eagle: When Refractory V-Fib Isn't

Resident Eagle is a monthly column profiling the work of top EMS physicians and medical directors from the Metropolitan EMS Medical Directors Global Alliance (the "Eagles"), who represent America’s largest and key international cities. For information on the Gathering of Eagles 2022, see useagles.org.

A 3-month-old boy from the U.K. suffered a ventricular fibrillation cardiac arrest. This persisted for more than 25 minutes, during which he received 10 defibrillation shocks. After the 10th his rescuers obtained return of spontaneous circulation. 

The unique feature about this child’s case was that his v-fib was not, in fact, refractory—it was recurrent. The shocks were effective but unrecognized by the rescuers, who could not see his underlying rhythm while performing CPR. Postevent analysis showed VF reoccurring within a few seconds each time and becoming the rhythm seen on the subsequent check by the EMS clinicians.

This case study appeared earlier this year in the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine¹ and was presented at the Gathering of Eagles conference in June by Michael Levy, MD, FACEP, FACP, FAEMS, EMS medical director for the state of Alaska and a number of additional EMS agencies. It illustrates that what providers may think is refractory arrest could, in fact, be multiple arrests recurring. 

In the case study the AED advised a shock following its initial analysis. The crew delivered that, then initiated compressions. They paused every two minutes for rhythm analysis, and at each of the first 10 analysis points, VF was identified, and a shock delivered.

They placed an IO needle in the right proximal tibia and an i-gel. They gave the child a single bolus of 30 mg amiodarone after the third shock and 60 mcg adrenaline following the third, fifth, and seventh shocks.

Following the seventh shock they contacted an advanced practice paramedic with specialization in critical care in the EOC. This senior clinician advised the medics to omit the next dose of adrenaline to ascertain whether excessive adrenergic stimulation was prolonging the arrhythmia.

An APP-CC arrived with the patient between the ninth and 10th shocks. He initiated a brief postshock pause following the 10th shock and immediately saw what appeared to be organized cardiac activity on the monitor. 

Refibrillation

So how often is what EMS providers believe to be refractory v-fib actually recurrent? “True refractory VF,” Levy notes, “seems to be very uncommon when defined as a VF that does not ever respond to defibrillation as compared to the relatively frequent event of recurrent VF.”

Levy also cited some earlier work by some of the same Scandinavian Journal authors. Their 2008 Resuscitation article described a cohort of patients with prehospital VF cardiac arrest for whom recorded signals were analyzed to determine with each shock if VF was terminated and a sustained organized rhythm was restored within 60 seconds.² 

In 465 of the 467 patients enrolled, the initial VF episode was terminated within three shocks. However, VF recurred in 48% of patients within two minutes of the first episode and in 74% sometime during prehospital care. The conclusions: Repeated refibrillation is common in patients with VF cardiac arrest. The likelihood of countershocks to terminate VF declines with repeated episodes of VF, yet shocks that terminate these episodes result increasingly in sustained organized rhythms.

Irritable Heart

Although many of the study patients’ initial response to shock was conversion to an organized rhythm, it was significant that almost half returned to VF within two minutes, Levy notes. Within a timeframe that typically is before the next rhythm check/pulse check, 74% had a VF recurrence at some point. 

“When these recurrences occur after a shock and resumption of chest compressions and then are defibrillated while CPR is ongoing, the next cycle check shows VF,” says Levy. “The reasonable conclusion when more than two of these occur is that the situation is refractory VF.”

It’s important to point out that recurrence of VF in many cases may be effectively the same as refractory insofar as something is making the heart very irritable. 

“Our greatest concern is that this represents an acute proximal coronary occlusion, causing a lot of myocardium to be at risk,” Levy adds. “VF is very energy-consumptive, and we need to try to terminate it as soon as we can early in the arrest, while it’s still ‘good’ VF, before it becomes ‘bad’ VF resulting in energy depletion and much less likely to convert with just defibrillation.

“Aggressive approaches to this problem—be it recurrent or refractory, including systems that move patients rapidly to ECMO and PCI—should be judged on their results but in my opinion are to be applauded for committing to a systems-based approach to attempting to improve outcomes in otherwise dire cases.”

Different Thinking

On the other hand, as in the United Kingdom case, there is a concern is that in some cases VF may have been precipitated by the ongoing chest compressions as well as the use of epinephrine.

“Monitor-defibrillator manufacturers have software allowing for a full review of many of the biological signals occurring during the resuscitation,” Levy says. “This allows postevent reviews that can clearly reveal an organized rhythm tucked into the artifact from chest compressions, as well as the recurrence of VF within those epochs. 

“While innovative technology can now serve as a real-time aid during CPR, this information is typically not available to resuscitation teams in real time.” 

How should EMS crews proceed if they suspect this might be the case? It’s a tough call.

“We must keep in mind the huge survival advantage we now enjoy since our guidelines began to emphasize the importance of maximizing compression fraction by such things as minimal pause, getting back on the chest before rhythm check, precharging the defibrillator before rhythm check, and immediate return to compressions after defibrillation,” Levy says. “Unquestionably, unless there are other signals, we need to stay with our party line for a minimum of three attempts at defibrillation and perhaps more. Once we find ourselves struggling with VF with each check, it might be time to start thinking different.” 

For example, the use of epinephrine remains an unsettled topic in adults, Levy points out.

“Beyond the simple yes/no of using the drug, the optimal dose, frequency, and total number of doses is not at all clear,” he says. “Some services have gone to smaller doses, and others use a drip instead of bolus, and others limit the total number of doses to 2–3 times 1 mg.

“Perhaps as we begin moderating the dose of epinephrine, we will see a reduction in cases of refractory VF.”

Levy notes that for those services using a 30:2 ventilation strategy, the pause during ventilation may provide a “cheat” for a rhythm check. 

“If an organized rhythm is seen, particularly if there has been an improvement in EtCO₂, it is time to stop compressions and assess the patient’s status,” he says.

The EMS clinician can carefully monitor the ongoing EtCO₂ waveform capnograph, Levy notes. 

“If there is an unexpected bump in the EtCO₂, maybe there is an underlying perfusing rhythm,” he says. “That’s worth a brief pause, always done after first establishing a palpable compression pulse.” 

In addressing the driving factor behind the value of a quick pause in resuscitation—a step not often taken on a routine basis—Levy says it may be worth waiting briefly to resume CPR until the postshock loss of signal has resolved to confirm that the rhythm is in fact refractory. 

“I have to emphasize how controversial this will be to some and would not strongly advocate it for all systems,” he says. “On the other hand, in selected cases for systems that have no advanced perfusion options, this may be the patient’s only chance.” 

References

1. Kingsley P, Merefield J, Walker RG, Chapman FW, Faulkner M. Out-of-hospital resuscitation of a 3 month old boy presenting with recurrent ventricular fibrillation cardiac arrest: A case report. Scand J Trauma Resus Emerg Med, 2021; 29: 58.

2. Koster RW, Walker RG, Chapman FW. Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest. Resuscitation, 2008 Sep; 78(3): 252–7.

Carol Brzozowski is a freelance journalist and former daily newspaper reporter based in South Florida.