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AEDs - Special Circumstances

AEDs (automated external defibrillators) are used to deliver a shock that is designed to halt a harmful and chaotic ventricular rhythm and restore normal sinus rhythm. Most AEDs are designed for use by lay rescuers and are simple to use, incorporating verbal commands to prompt the AED user. There are certain circumstances that will change the way an AED is typically used, or may require the rescuer to perform an additional step prior to shocking the victim. Let’s examine some of these special circumstances and the interventions they require.

Medication patches - these days, many different medications are being delivered via the transdermal route, including nitroglycerin, pain medication (i.e. Fentanyl), birth control and antinausea medications such as Scopolamine. If you notice a patch on your victim, simply remove the patch. If there is residue left behind, you can quickly wipe the excess medication off. The nonadhesive backing of some patches has a metallic component (usually aluminum but sometimes titanium) - this is why you should remove the patch before delivering a shock to your victim, so as to avoid arcing and thermal injury. It is also the reason that some patches should not be cut in half).

Hair - Many male patients have hairy chests, which may prevent AED pads from sticking well to the chest. This may also prevent the AED from delivering an effective shock to the victim. The American Heart Association 2010 BLS for Healthcare Providers video recommends using a set of AED pads as depilatory agents. This may not be the best idea- what if there is only one set of pads included with the AED? In addition, these pads are very expensive and it seems a shame to waste a set of pads just to remove hair. Instead, we recommend using a razor to quickly shave any excess hair. Don’t worry about nicks- your victim won’t mind! We recommend adding a razor to every AED kit.

Water - many people hold the mistaken belief that if the victim is laying in even a tiny amount of water they, too, will receive a shock when the victim is defibrillated. This is simply not true (at least, not if you are ‘hands off’ the victim, as you should be when a shock is about to be delivered). Of course, the victim should be laying on a firm surface for CPR, so if the victim is in the water or is lying in a large amount of water you will want to pull the victim to a dry area. Rest assured that a small amount of water won’t hurt. If you are really concerned, or if you are afraid that the AED pads will not stick because the victim is wet or has been sweating profusely (as some heart attack victims do), quickly wipe the victim’s chest dry. Your sleeve will do in a pinch.

Pacemakers - your victim may have a pacemaker implanted just below the skin. They are usually in the upper left chest and will be similar in size to a deck of cards. You may see a scar over the area. Some patients may have a pacemaker in their upper right chest, just where you would normally place an AED pad. You should avoid placing an AED pad over a pacemaker if at all possible (although if the victim is in arrest, there is a chance their implanted defibrillator is not working anyways). Remember: when you are placing the AED pads, your goal is to “sandwich” the heart. Current runs from one pad to another, going through the heart as the energy traverses from pad to pad. When you think about it this way, you will realize that placing the AED pad a few inches below where you would normally place it is still acceptable. If you are really concerned, you can use anterior- posterior placement, where the left chest AED pad (usually conveniently marked with a heart) remains on the left chest and the pad that would normally go on the right chest just below the collarbone is moved to the left side of the back. In this way, you are still sandwiching the heart between the two pads, and the electrical energy will still pass directly through the heart between the two pads.

The extremely thin patient - some patients are very thin, so that placing two AEDs pads on their chest without the pads touching or overlapping becomes impossible. If your patient is very thin, you may use the anterior-posterior placement method described above. You may also use this pad positioning for small children when you are forced to use adult pads for defibrillation, or on infants when you are using any pads other than infant-sized pads.

AED use is generally very straight-forward but, as can be seen, you may be thrown a curve ball once in awhile. Should you encounter a special circumstance like those listed above, try not to panic. Think through the problem and remind yourself that without your intervention the patient is unlikely to survive.