Should We Shock in the Wilderness: Taking AEDs into the Backcountry

AED  Medical devices are becoming more miniaturized by the day, making them more accessible, more affordable, and easier to transport…but just because we can, does it really mean we should?  A paper recently released describes this exact dilemma regarding automated external defibrillators (AED), and argues against their utility and appropriateness in the wilderness setting.1

A brand new AED can be bought from the online marketplace for somewhere between $1200 and $1700.  While this is not necessarily ‘cheap’, this is incredibly more affordable compared to the past.  Also, whereas the old defibrillators were around the size of a large stereo and weighed at least as much, the newer AEDs can be as small as a regular box of crackers and weigh only around five pounds.  In backpacking, five pounds is still not ideal, and may be the same weight as your sleeping bag and tent combined.  But if it means saving a life from cardiac arrest out in the wilderness it should be brought along…or should it?  There are multiple issues with bringing an AED into an austere environment.  The authors recommend one should be brought along only if a specific risk can be identified that justifies its inclusion, and that careful planning with extraction contingencies need to be considered.

Heart Shock

The authors make the argument that even under the ideal circumstances of having the AED immediately accessible and getting successful defibrillation, most circumstances that lead to cardiac arrest require immediate definitive care which would not be accessible.1  Then there is the concern that merely throwing in an AED to a wilderness medical kit blindly will cause the standard of care to shift to where an AED is always required in these kits regardless of the medical necessity or risk assessment.  Given the cost and weight of the devices, this is not a responsible allocation of resources. Actual risk should be taken into account, and misconceptions, such as lighting strikes or submersion injuries commonly causing ventricular fibrillation (asystole is more common), need to be understood.1  The equipment itself is not ideal for wilderness travel, and the weatherproof cases aren’t built to withstand extreme conditions.  Many of the models will fail if not kept within a specific operating temperature range, which is more conservative than temperatures experienced on many wilderness expeditions.

In a wilderness race competitions, the question further becomes where to place the AED.  Especially with long distance races such as ultra-marathons, participants can be separated by tens of miles.  If/when a downed participant is noticed by another competitor, it would take a great deal of time to get word to the medical team and then transport the medical equipment to the participant for treatment.  Considering the importance of time to first shock, the time delay could severely decrease the effectiveness of the AED overall.

Marathon Runner down The authors do emphasize the benefits of AEDs in emergency medical services (EMS) systems.  Recent studies have shown that EMS AED use has improved survival with favorable neurologic outcomes in patients with shockable first rhythms, and significantly increased the number of patients surviving to emergency department and surviving to hospital discharge.2,3,4 However, EMS crews have easily accessible transportation to definitive care and other advanced medical supplies such as airway equipment and intravenous fluids, that a field medic will likely not have access to.  But even if they do, that still means having to evacuate a patient from the back country while attempting to maintain their airway, continue to breathe for them and continuously monitor them in case they go back into cardiac arrest.  The specific risks of any wilderness expedition should be well thought out beforehand, but when deciding on the inclusion of advanced medical equipment consider all the logistics of evacuation and transport that follow its miraculous use.

References

  1. Joslin, J. D., & Biondich, A. S. (2016). Should AED Devices Be Routinely Included in Wilderness Medical Kits? Wilderness & Environmental Medicine, 27(1), 4-6. doi:10.1016/j.wem.2015.11.003
  2. Blom, M. T., Beesems, S. G., Homma, P. C., Zijlstra, J. A., Hulleman, M., Hoeijen, D. A., . . . Koster, R. W. (2014). Improved Survival After Out-of-Hospital Cardiac Arrest and Use of Automated External Defibrillators. Circulation, 130(21), 1868-1875. doi:10.1161/circulationaha.114.010905
  3. Public-Access Defibrillation and Survival after Out-of-Hospital Cardiac Arrest. (2004). New England Journal of Medicine N Engl J Med, 351(7), 637-646. doi:10.1056/nejmoa040566
  4.  Declerck, M. P., Atterton, L. M., Seibert, T., & Cushing, T. A. (2013). A Review of Emergency Medical Services Events in US National Parks From 2007 to 2011.Wilderness & Environmental Medicine, 24(3), 195-202. doi:10.1016/j.wem.2013.01.009