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Knowing Your ABCs About AEDs Could Save a Life

By Neha P. Raukar, MD, MS FACEP on October 09, 2019 hst Print

Editor’s Note: The following information on AEDs is designed for athletic directors and school administrators to share with others within the school setting so that more people are capable of using the device.

Sudden Death in Athletes

Considered to be models of physical health, athletes who die suddenly can be a shocking event. Fortunately, the rate of death in youth athletes is low, but when it occurs, it devastates the community well beyond the athletic arena.

An automated external defibrillator (AED) is a very sophisticated, but lightweight, portable and an easy-to-use piece of medical equipment that is used to resuscitate people who are having a heart attack. The goal of the AED is twofold: first to identify those victims who are having an abnormal electrical heart rhythm and, second, to shock them back into a normal heart rhythm. To understand why the AED is so useful, it is helpful to first understand a little bit about cardiac physiology.


The heart has four chambers that act in a very coordinated way to pump blood through the lungs and around the body. The pumping of the four chambers is an organized process coordinated by the electrical system. Each chamber fills up with blood, the chamber receives an electrical signal, and the blood is squeezed out of the heart. If the electrical system is compromised, the chambers of the heart can either stop squeezing (asystole) or will squeeze in a very uncoordinated manner (fibrillation) and very little blood actually gets pumped out of the heart.

The goal of the AED is to identify those patients whose heart is fibrillating, and shock them, resetting the electrical system and coordinating all of the chambers. Shocking the asystolic heart (flatlined) does not restart the heart because there is no electrical rhythm to reset (it seems to work very well on TV but in real life, shocking a flatlined heart does not work), but shocking the fibrillating heart is a very effective way to restore circulation and save a life.

How Does the AED Work?

Adhesive electrodes are attached to the victim’s chest and a microprocessor analyzes the electric rhythm of the heart (some defibrillators do this automatically; some require you to press the “Analyze” button). It determines whether defibrillation (a shock) is needed and, if so, a voice prompts the user to press the “Shock” button. The shock is delivered through the same adhesive electrodes which “resets” the rhythm of the heart. It does this by momentarily stopping the heart and allowing its own electrical conduction to take over.

Who will Respond to an AED?

Most of what we know regarding cardiopulmonary resuscitation (CPR) in young athletes (athletes less than 35 years old) is based on observational studies in humans as few clinicians have had the experience of running many sideline codes. Thus, we have to rely on databases to better recognize patterns which can inform interventions. A study in 1996 found that of 158 sudden deaths in athletes in the United States, 84 percent were due to cardiac causes, many of which cause death by precipitating an abnormal ventricular rhythm. In 2003, a larger study looked at the cause of death in 387 young American athletes, and of the top 20 reasons athletes died, 15 were cardiac and accounted for more than 90 percent of the deaths.

How Long Do I Have to Shock the Heart?

When the heart enters an abnormal rhythm, the brain and the rest of the body are no longer getting blood because the heart is not pumping it. Therefore, it is important to restore a normal cardiac rhythm as quickly as possible. For each minute that the heart stays in an abnormal rhythm, the odds of survival are reduced by about 10 percent. If the average response time for EMS is 10 minutes, often a lot longer in more remote areas, that means there is a very slight chance of survival if we rely only on EMS. On-scene defibrillation offers the best chance of survival in these young athletes.

Like most emergencies, the single most important factor for improving the survival of the victim is a well-prepared, time-conscious, team approach.

Step-by-step Guide on How to Use the AED

  1. Confirm that the patient is unable to respond by shaking them and loudly calling their name.
  2. Send someone to call 911. If you are alone, call 911 first.
  3. Start CPR.
  4. Turn the AED on.
  5. Follow the voice prompts. Depending on the model of the AED, you may have to attach the cable to the pads or to the AED machine.
  6. Prepare the chest. The pads need to be attached to the bare chest, not over a shirt. If the chest is very hairy, it will need to be quickly shaved. The patient should be dry to use the AED. If the patient is wet or covered in sweat, the chest wall should be quickly wiped down so the adhesive electrodes will stick to the chest. The pads should not be placed over a pacemaker (which is very obvious when looking at the chest wall) and if the patient is a woman, the bra should be removed as underwire will conduct electricity. Also, the pads should be placed at least an inch away from any metallic piercings.
  7. Apply the pads. The pads should be placed in a location that optimizes the chances for the shock to be effective by conducting the most amount of electricity through the heart. Typically, one pad is placed on the right upper chest just below the collarbone and the other on the left side of the chest, under the armpit along the nipple line. There is usually a picture on the machine with the locations well identified. If the pads are not placed properly, the machine will prompt the user to check the placement of the pads.
  8. Let the AED analyze the rhythm. Pause CPR while the machine analyzes the rhythm. If no shock is advised, because the patient is not in an abnormal rhythm or has a pulse, then the machine will advise you to continue CPR or stop.
  9. Follow the voice prompts. If the machine prompts you to shock the patient, first confirm no one is touching the patient and then press the button. The patient will jolt and this is normal. The AED will only give one shock at a time and after shocking the patient, the user will be instructed to resume CPR.
  10. Continue CPR for two minutes and then allow the AED to check for a rhythm. Most AEDs will remind you when the two minutes have elapsed so it can check the rhythm. Repeat the cycle until either the AED says the patient has a normal rhythm at which time CPR should be stopped, if the patient starts breathing or regains consciousness at which time CPR should also be stopped, or until EMS arrives. While the AED can be used for over 60 minutes, the chances for survival after 60 minutes of CPR are minimal.