When a person is experiencing sudden cardiac arrest (SCA), they only have a short window of time to be resuscitated. In cardiac arrest, the person’s heart stops beating rhythmically and instead flutters or quivers chaotically. If nothing is done, heart activity ceases completely. If the person dies, this is referred to as sudden cardiac death.
Automated external defibrillators can often restore a normal rhythm during those critical first moments, saving the victim’s life. There are some cases in which you should not use an AED. However, those cases are extremely rare. Knowing when and when not to use a portable defibrillator can help you be better prepared.
Situations in Which You Shouldn’t Use an AED
There are certain rare instances when using a defibrillator may be unwarranted or ineffective. You should avoid administering an electric shock if:
The Person Is Suffering From a Heart Attack
It’s common to confuse heart attack and cardiac arrest. However, these are completely different conditions with different protocols. A heart attack is a plumbing issue while cardiac arrest is an electrical issue. An electrical shock from an AED will not help in the case of a heart attack because the cause of a heart attack is not electrical.
The good news is that it’s easy to tell the difference between a heart attack and cardiac arrest. If the person is in pain but is still breathing and responsive, it’s most likely a heart attack or another problem that does not require an AED (note: you should still call 9-1-1 or take the person to the emergency room). If the person is unresponsive and not breathing or is only breathing in gasps, you’re probably dealing with cardiac arrest and should defibrillate as soon as possible.
The AED Is Faulty or Has Expired Parts
AEDs perform daily, weekly, and monthly self-tests to ensure readiness. When you turn on the device, it should confirm—via a green light or other on-screen indicator—that the device is ready to use. Also check the expiration date on the battery and electrode pads. The device won’t be able to do its job and may endanger the victim if it has a low or expiring battery. In this case:
- Call 9-1-1.
- Perform hands-only CPR.
- Send someone to look for another defibrillator.
- Continue to perform hands-only CPR while you wait for the emergency services to arrive.
The Victim Has a DNR
This is more of an ethical issue than a safety issue, but it is still important to address. If you see a “Do Not Resuscitate” tattoo or DNR bracelet on the victim, defibrillation may violate their wishes.
You probably won’t be subject to legal recourse for treating the individual. Good Samaritan laws will protect you in most cases. Nevertheless, if you do see evidence of a do-not-resuscitate order before taking action, you’ll need to make the difficult decision of whether to honor the victim’s expressed wishes or save their life regardless.
When to Use a Defibrillator
An automated external defibrillator should always be used when someone goes into cardiac arrest unless the device is inoperable or the victim has clear evidence of a DNR order and you decide to respect their wishes.
The first sign of cardiac arrest is usually fainting. If the victim appears unresponsive, try shaking, pinching, and shouting at them. If they appear unconscious or in a seizure-like state, and they don’t appear to be breathing or are only breathing in gasps, you’re most likely dealing with SCA. In this case:
- Start chest compressions while someone else calls 911. Cardiopulmonary resuscitation with rescue breaths should only be attempted by a trained rescuer.
- Send someone to fetch the nearest AED.
- Attach the AED pads to the person’s chest according to AED pad placement guidelines and follow the voice instructions.
Remember that every second matters. A cardiac arrest victim’s chance of survival reduces by around 5.5% for every minute without CPR, defibrillation, and definitive care, so it’s essential to act immediately.
In some cases, special considerations when using an AED may apply. While these considerations should not deter you from using a defibrillator, they may influence how you administer treatment.
The Victim Is Wet or Lying in Water
Water and electricity don’t mix. If a cardiac arrest victim is wet or lying in water, move them away from the liquid and dry their chest completely before attempting to administer a shock. In addition, if there are any combustible materials nearby, such as solvents or fuel, move away from the source of the materials before using the device.
The Victim Has a Medication Patch or Pacemaker
A pacemaker is easy to spot. It’s about half the size of a deck of cards and will look like a hard lump in the victim’s chest. Do not place an AED pad directly on top of a pacemaker as the pacemaker could block some of the shock . Instead, place it as close to the target area as possible without touching the pacemaker.
If the patient is wearing a medication patch on their chest, quickly remove it and rapidly wipe the area before applying the pad. Do not attempt to place the pad directly over the patch, as the patch could compromise the effectiveness of the shock and may cause small burns .
The Victim Has a Hairy Chest
Excess body hair can interfere with the AED’s ability to detect a shockable rhythm. The AHA provides the following guidelines:
- If a razor is available, shave the target area before applying the pads.
- If no razor is available but you have a second pair of electrode pads, press down hard on the pads and rip them off quickly to remove as much hair as possible. Then, apply the second set of pads.
- Apply as much direct pressure to the pads as possible to ensure conduction. (Just make sure not to touch the victim’s bare skin while administering a shock.)
Infants, Children, and Pregnant Women
Portable defibrillators can be used on infants (under one year of age), children, and pregnant women. Take the following into account:
- Use pediatric pads or an infant/child setting (if available) for infants and children under 8 years of age or around 55 lb (25 kg). These pads or settings attenuate the dose of the shock. If child pads are not available, use the adult pads.
- Make sure that the pads don’t touch each other. For an infant or small child, it may help to use an anterior-posterior pad placement in which one pad is placed in the center of the chest, immediately left of the sternum, and the other pad is placed in the center of the upper back, between the shoulder blades.
- Defibrillators can be used on pregnant women without any modifications. If the patient is wearing a bra, remove the bra first (cutting it, if necessary) to ensure unobstructed access to the chest. You can always ask some bystanders to stand around the patient, facing outwards, to protect her dignity.
External Defibrillator Side Effects
In most cases, an automated external defibrillator works without causing harmful side effects. However, if the device is improperly administered, it may fail to deliver the necessary shock. This may keep the victim in cardiac arrest.
If the person is sensitive to the adhesive gel on the defibrillator pads, they may experience contact dermatitis. However, the instance covered in the linked case study was related to a wearable cardioverter defibrillator, was treated effectively with topical medication, and cleared up within a couple of weeks of pad removal (so it’s not a great cause for concern). By heeding the guidelines above, you can also minimize the likelihood of other side effects, such as burns.
What If There Is No Shock Advised?
There could be some situations in which a defibrillator analyzes the victim’s heart rhythm and returns a message of “no shock advised.” In this case, you should continue with chest compressions and leave the electrode pads attached in case the patient’s heart rhythm changes to an AED shockable rhythm, such as ventricular fibrillation or ventricular tachycardia.
You Have Just Minutes to Decide
It’s generally easy to determine when to use and when not to use a defibrillator. To recap it as simply as possible, it all rests on three basic questions:
- Is it cardiac arrest?
- Is the AED operable?
- Is it safe to deliver electric shocks to the victim?
If you can answer yes to all three questions, it’s time to grab the defibrillator. If the answer to any of the above questions is no, consider other options.