The CellAED - What is the hype about?

22nd January 2024

The CellAED has caused quite a stir with the promise of not only an ultra-portable but cost-effective AED.  It sounds too good to be true?

The device has been met with skepticism, mostly around the low energy delivered ( 75 joules versus the recommended 150 Joules) and scant evidence of proof of concept.  I.e. does it actually work?

In theory, it absolutely should; the device has been assessed as having met the standards of IEC 60601-2-4:2010 (Medical Electrical Equipment - Part 2-4: Particular requirements for the basic safety and essential performance of cardiac defibrillators) assessed by three regulatory or notarized bodies independent of each other for CE Mark (0297), UKCA (0086) and TFDA.  In addition, CellAED was also assessed by the NHS for inclusion on the NHS supply chain framework.

All of this confirms that the device has been manufactured to meet the standards required for usage and sale.

Recent marketing from the manufacturer, Rapid Response Revival, claim “CellAED® has now been used in 20 real world cases and has performed as intended by accurately analysing heart rhythms and appropriately delivering shocks.” but without any actual evidence or statistic data.

1,000 CellAED devices have been donated to the First Responder Shock Trial (FIRST) (1) in Australia which was rolled out in November 2022 and is due to completed in November 2024, which should demonstrate proof of concept, if not, interesting results.

Why is the 75 Joules claim so contentious?

The big issue is that the CellAED frequently promotes its ability to effectively defibrillate using only 75 Joules with each shock whilst ILCOR, RCUK and ERC guidelines have a requirement of a minimum of 150 Joules for defibrillation.

“The initial biphasic shock should be no lower than 120 J for RLB waveforms and at least 150 J for BTE waveforms.  For pulsed biphasic waveforms, begin at 12-150 J.  Ideally, the initial biphasic shock energy should be at least 150 J for all biphasic waveforms in order to simplify energy levels across all defibrillators, particularly because the type of waveform delivered by a defibrillator is not marked.”

European Resuscitation Council Guidelines 2021: Adult Advanced Life Support (2)

And this has caused quite a hoo haa.

Relatively few studies have been published with which to refine the defibrillation energy levels set in the 2010 guidelines (3).  There is no evidence that one biphasic waveform or device is more effective than another.  First shock efficacy of the BTE waveform using 150J (4) has been reported as 86-98%. (4, 5).   First shock efficacy of the RLB waveform using 120J has been reported as 85%. (6).

Four studies have suggested equivalence with lower and higher starting energy biphasic defibrillation (7-10) although one has suggested that initial low energy (150J) defibrillation is associated with better survival (11).

But…

On page 61 of the instruction manual, it states that the energy output and delivery is 150 Joules and on page 15 it states “The defibrillator delivers up to 150 Joules of electrical energy with every shock delivery” which is confusing because all of their literature talks about how it is able to deliver a successful shock with only 75 Joules due to its unique “Equal Leading Edge Biphasic Exponential”  (ELEBE) which distributes the energy 50:50 between both phases, compared to conventional defibrillators which divide the energy typically 70:30 across both phases of the more conventional BTE or RLB waveforms. 

CellAED claim that their unique energy delivery through ELEBE requires less energy (Joules) to deliver the shock with equal current (Amps)  as conventional defibrillators.

Most conventional AEDs store their energy in a single high voltage capacitor which delivers an uneven (70:30) waveform across the phases which requires high energy (120-150 Joules) to ensure the second phase has enough energy to complete the defibrillation.  As all of the energy is being provided by a single capacitor, after the first phase, a significant amount of energy has been lost, leaving less energy available to complete the second phase.

The CellAED uses separate capacitors to provide independent energy for each phases ensuring a 50:50 distribution of energy across each phase – they argue that only 75 Joules per phase is required for each phase (totaling 150 Joules) for the complete cycle.

The argument is that comparing AEDs based on energy use (Joules) is not necessarily a representative comparison of efficacy, because of the variations of waveform differ between AEDs, the most critical factor in determining shock effectiveness is not Joules but the Current (Amps) (12).

Time from Activation to First Shock

Another issue is the time it takes for the device to analyse, charge and deliver a shock from activation, which is stated ‘less than 50 seconds’.

50 seconds?!    That is nearly a minute off the chest where CPR is not being performed.

CellAED User Manual p.53

Compare this to the Schiller FRED Easyport Pocket of <22 seconds (p.83 of User Manual ) or 15 seconds for the Cardiac Science G5 AED (pB-2 of User Manual)

The CellAED is slow and effective CPR relies on minimum time off the chest as possible.

The length of time required to deliver the shock is the compromise, not the low current.  And being 35 seconds slower than one of the fastest AEDs is a compromise, it is not a failing.

Summary

The benefit of the CellAED remains; an ultraportable AED for ‘just in case’.  How much time will you save by having the AED immediately available in your bag, desk or glove box rather than waiting for someone to find an AED for you?    Probably a great deal more than 35 seconds. And while time off the chest is critical in resuscitation, the single most important factor in terms of a successful resuscitation remains the time to the first shock.

If you are working operationally to provide first aid or medical care, there is no reason to not have the best, dedicated, AED within your kit that you can afford, otherwise, there are very few reasons not to have a ultraportable emergency AED in your vehicle or day bag.

I am a huge fan of the Schiller FRED Easyport which is so diminutive it easily fits into a bumbag and I’ll have this with me if I am working on overt or low/no-profile projects, meanwhile, the CellAED lives quietly in my day bag and another on in my glove box, just in case.

Until there is a better alternative, the AED you have on you will always be better than the one you don’t have.

References:

1. Todd V, Dicker B, Okyere D, Smith K, Smith T, Howie G, Stub D, Ray M, Stewart R, Scott T, Swain A, Heriot N, Brett A, Mahony E, Nehme Z. (2023) “A study protocol for a cluster-randomised controlled trial of smartphone-activated first responders with ultraportable defibrillators in out-of-hospital cardiac arrest: The First Responder Shock Trial (FIRST).” Resusc Plus. Sep 6;16:100466.

2. Soar J, Böttiger BW,  Carli P, et al.  (2021)  ” European Resuscitation Council Guidelines 2021: Adult advanced life support”.  Resuscitation.  115-151.

3. Deakin CD, Nolan JP, Soar J, et al.  (2010)  “European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support”.  Resuscitation.  (81):1305 52.

4. van Alem AP, Chapman FW, Lank P, Hart AA, Koster RW.  (2003)  “A prospective, randomised and blinded comparison of first shock success of monophasic and biphasic waveforms in out-of-hospital cardiac arrest”.  Resuscitation.  58:17 24.

5. White RD, Blackwell TH, Russell JK, Snyder DE, Jorgenson DB.  (2005)  “Transthoracic impedance does not affect defibrillation, resuscitation or survival in patients with out-of-hospital cardiac arrest treated with a non-escalating biphasic waveform defibrillator”.  Resuscitation.  64:63 9.

6. Morrison LJ, Henry RM, Ku V, Nolan JP, Morley P, Deakin CD.  (2013)  “Single-shock defibrillation success in adult cardiac arrest: a systematic review”.  Resuscitation.  84:1480-6.

7. Stiell IG, Walker RG, Nesbitt LP, et al.  (2007)  “BIPHASIC Trial: a randomized comparison of fixed lower versus escalating higher energy levels for defibrillation in out-of-hospital cardiac arrest”.  Circulation.  115:1511 7.

8. Walsh SJ, McClelland AJ, Owens CG, et al.  (2004)  “Efficacy of distinct energy delivery protocols comparing two biphasic defibrillators for cardiac arrest”.  American Journal of Cardiology.  94:378 80.

9. Olsen JA, Brunborg C, Steinberg M, et al. (2019)  “Survival to hospital discharge with biphasic fixed 360 joules versus 200 escalating to 360 joules defibrillation strategies in out-of-hospital cardiac arrest of presumed cardiac etiology”.  Resuscitation.  136: 112 8.

10. Anantharaman V, Tay SY, Manning PG, et al. (2017)  “A multicenter prospective randomized study comparing the efficacy of escalating higher biphasic versus low biphasic energy defibrillations in patients presenting with cardiac arrest in the in-hospital environment”.  Open Access Emergency Medicine.  9:9-17.

11. Schneider T, Martens PR, Paschen H, et al.  (2000)  “Multicenter, randomized, controlled trial of 150-J biphasic shocks compared with 200 to 360-J monophasic shocks in the resuscitation of out-of-hospital cardiac arrest victims. Optimized Response to Cardiac Arrest (ORCA) Investigators”.  Circulation.  102:1780 7.

12. Ristagno G, Yu T, Quan W, Freeman G, Li Y.  (2013)  “Current is better than energy as predictor of success for biphasic defibrillatory shocks in a porcine model of ventricular fibrillation”. Resuscitation.  1;84(5):678-83.