*Note
- this discussion is only pertinent to modern biphasic defibrillators
with self adhesive electrodes applied only anterior/posterior or
anterior/lateral, with the compression provider wearing two pairs of
gloves (double-gloving), with a maximum defibrillation
energy of 360J.*
We
have all heard the chant, “I’m clear, you’re clear, we’re all clear,”
prior to a provider double, triple, sometimes quadruple checking him or
herself before pushing that magic red button with the white lightning
bolt - “shock”! Recent literature has spurred quite the discussion on
hands-on defibrillation (HOD) - CPR where compressions continue
throughout the defibrillation - as it is widely known that interruptions
in chest compressions lead to poor patient outcomes and are all too
common, for example, during intubation, providing ventilations, AED
analyzing, charging, and during defibrillation shocks.
This pearl is meant to provide a very brief explanation of what your
risks might be, what protection devices you might use, anecdotal and
published accounts on HOD, and suggestions for your clinical practice.
There
are numerous factors in regards to energy and the effect it may have on
the provider during HOD. Energy is the product of voltage, current and
time. Neither factors, independently, are sufficient in inducing
damaging effects. For example, several thousand volts are experienced
during static electricity, although the current is very low. Current is
determined by the resistance between the electrodes of the
defibrillator, the electrode gel, the gel-skin contact, and the tissue
resistance. Glove integrity, skin moisture and the actual current
pathway will determine the amount of escape current. Biphasic defibrillators provide voltages up to approximately 2200 V over approximately 15-20 msec.
The maximum permissible leakage current, per the International
Commission on Non-Ionizing Radiation Protection is 1mA; the threshold
for perception is 2.5-4.0 mA; and pain is experienced at 6-10 mA.2 Sullivan and Chapman studied the voltage-current curves for gloves.
They note the international safety standard on 1mA and explain that at
this level, it would take 1-3 seconds of current flow to induce VF in
<5% of the population. While defibrillation shocks are usually less
than 20 msec, even if the pulse is timed appropriately in the rescuer’s
cardiac cycle, as much as 500 mA would be required to induce VF.1 For reference, the current exposure from a home body fat monitoring scale is 500 uA.
In
one of the most exciting studies, Lloyd et al measured current between
“rescuers” and patients undergoing cardioversion at up to 360 J and found
the highest current leak measured was 907 uA,4 with no “rescuers” experiencing a “shock.” Neumann et al found HOD was
safely performed on pigs by rescuers, HOD shortened pauses during CPR,
and it more quickly restored coronary perfusion pressure.4 Kurz and Sawyer, in their letter to the editor of Resuscitation, advocate eliminating effects of no-flow time, perhaps by using HOD.7 Dr. Scott Weingart writes that in the 4 years that he and his
colleagues have been performing HOD, there have been no rescuer
complications, although occasional perceptions of tingling have been
reported. He himself reported arm soreness after 3 shocks, all at 360 J
with the electrode pads notably in the anterior/anterior position.
In
opposition, Lemkin et al derive an equation called the rescuer-received
dose, to try to better qualify defibrillation risk. Noting that energy
values greater than 1 J reportedly can cause VF, they deem HOD unsafe as
values above 1 J were calculated in their cadaver study, though effects of gloves were not accounted for.
Two studies from the UK found that medical examination gloves do not
provide rescuer safety and even demonstrate further glove breakdown of
the gloves worn by rescuers who perform compressions.
According to Sullivan and Chapman, HOD with medical examination gloves
will produce no sensation at all unless the gloves completely break down.1
Although
there are no reported fatalities or serious consequences to rescuers
performing HOD under ideal conditions - using a biphasic defibrillator
with electrodes placed appropriately, with rescuers
double gloved - we should take note that any change to a safety protocol
should not be undertaken without ensuring rescuers' safety.
I have personally performed HOD, as have my colleagues in the emergency
department. While none of us have experienced any detrimental
consequences or even the reported tingling, considering the literature,
perhaps we should currently hold off on changing our protocols to
mandate hands-on defibrillation. Protocols that need to be changed or
followed are as follows:
- High quality CPR remains of utmost importance. Set a metronome at 100 beats per minute and compress the chest to 1.8” (or as close to it as possible) every time.
- Have
no interruptions in chest compressions - not for intubation, not for
starting an IV, not for inserting a central line, not for transporting,
and not for charging the defibrillator!
The
use of HOD needs to reflect your clinical decision made in the best
interest of you, your co-rescuers, and your patient. If you chose to do
so, please double-glove, please place the electrodes
anterior/posterior, and communicate your practice
to your colleagues.
References
1.
Sullivan JL, Chapman FW. Will medical examination gloves protect
rescuers from defibrillation voltages during hands-on defibrillation?
Resuscitation. 2012 Dec;83(12):1467-72. doi: 10.1016/j.resuscitation
2012.07.031. Epub 2012 Aug 25. PubMed PMID: 22925991
2. Petley
GW, Cotton AM, Deakin CD. Hands-on defibrillation: theoretical and
practical aspects of patient and rescuer safety. Resuscitation. 2012
May;83(5):551-6. doi: 10.1016/j.resuscitation.2011.
3. Sullivan
JL. Letter by Sullivan regarding article, "Hands-on defibrillation: an
analysis of electrical current flow through rescuers in direct contact
with patients during biphasic external defibrillation". Circulation.
2008 Dec 2;118(23):e712; author reply e713. doi: 10.1161/CIRCULATION
AHA.108.803718. PubMed
PMID: 19047587.
4. Lloyd
MS, Heeke B, Walter PF, Langberg JJ. Hands-on defibrillation: an
analysis of electrical current flow through rescuers in direct contact
with patients during biphasic external defibrillation. Circulation. 2008
May 13;117(19):2510-4. doi: 10.1161/CIRCULATION AHA.107.763011. Epub
2008 May 5. PubMed PMID: 18458166.
5. A note of caution on the performance of hands-on biphasic defibrillation. Weingart SD. Resuscitation. 2013 Mar;84(3):e53. doi: 10.1016/j.resuscitation.2012.
6. Lemkin
DL, Witting MD, Allison MG, Farzad A, Bond MC, Lemkin MA. Electrical
exposure risk associated with hands-on defibrillation. Resuscitation.
2014 Oct;85(10):1330-6. doi: 10.1016/j.resuscitation.2014.
7. Petley
GW, Deakin CD. Do clinical examination gloves provide adequate
electrical insulation for safe hands-on defibrillation? II: Material
integrity following exposure to defibrillation waveforms. Resuscitation.
2013 Jul;84(7):900-3. doi: 10.1016/j.resuscitation.2013.
8. Deakin
CD, Lee-Shrewsbury V, Hogg K, Petley GW. Do clinical examination gloves
provide adequate electrical insulation for safe hands-on
defibrillation? I: Resistive properties of nitrile gloves.
Resuscitation. 2013 Jul;84(7):895-9. doi: 10.1016/j.resuscitation.2013.
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