How AED Defibrillators Work


The purpose of an AED is to restore a normal heart rhythm in the event of sudden cardiac arrest. In order to do this, it administers an electric shock. There are a few different types of defibrillators, from manual ones that require training, to automated external defibrillators that are more beginner-friendly and commonly found outside hospitals. These devices are life-saving kits that can be used by anyone who is trained on how to use them, even non-medical personnel like police officers, fire service workers, flight attendants, and security guards. 

What AED Defibrillators Do

Defibrillators work by analyzing the electrical pattern of the victim’s heart. They do this by placing electrode pads, or electrodes, on the victim’s chest. The device will tell the user where to place them and can also have spoken prompts, as well as a display, to guide them through the process. Once the pads are positioned, the device will reanalyze and determine whether or not a shock is necessary.

If the AED determines that a shock is needed, it will then charge its internal capacitor in preparation for delivering the shock. The shock itself is delivered in a biphasic waveform, meaning that the current flows in a positive direction and then reverses for a similar span of time. This allows for less energy to be administered, which helps to reduce myocardial damage.

After the shock is given, the AED will ask for CPR to be administered, and it will continue to monitor the heartbeat of the victim until medical professionals arrive. Those who are untrained can still use an AED, though they must ensure that there is no water on the victim’s chest. This is because the electrical shock will travel through the water and not directly into the heart, which could be very dangerous for someone who is unconscious and unresponsive.

Find Great AEDs

If you’re looking for an AED, offers a wide selection online from brands you can trust, including ZOLL, Stryker, Philips, LIFEPAK, and more. Because there are so many options to choose from, we offer a Buyer’s Guide to help you select the right one for your situation. If you have any additional questions, speak with one of our AED experts to get additional information and advice. We’re here to help you find a great AED defibrillator that you can rely on!