What Is Automated External Defibrillation (AED)?

What Is Automated External Defibrillation (AED)?

It’s common for people to wonder what is Automated External Defibrillation (AED). If you underwent first-aid and CPR training, you already know the answer. But for those with less knowledge of this concept, it is one of the most effective quick-response measures that can save the life of a cardiac arrest victim.

There’re many ways to explore the operation of AEDs – from analyzing the heart’s rhythm to delivering electrical shocks to ventricular fibrillation victims. Simply put, Automated External Defibrillation, also known as AED, is a process that can restore the heart rhythm with an electrical device.

To bring this method closer to you and clarify any unknowns, we will elaborate on the Automated External Defibrillation process, its functions, and how it saves lives.

The Definition of AED

To understand what Is automated external defibrillation, we must clarify what defibrillation means. Simply put, defibrillation is the treatment of arrhythmias related to cardiac arrest with electrical currents. Ventricular tachycardia and fibrillation are the most frequently treated arrhythmias.

The defibrillator has two main functions – to analyze the heart’s rhythm and, when necessary, deliver an electrical shock. There’re many defibrillator types, including the Automated External Defibrillator (AED), the Wearable Cardioverter Defibrillator (WCD), and the Implantable Cardioverter Defibrillator (ICD).

All defibrillator types have the same function – restoring the normal heart rhythm. However, our matter of concern is the Automated External Defibrillator – an electrical device that automatically diagnoses the occurrence of arrhythmia and delivers a shock to correct it.

It’s called the Automated External Defibrillator because – contrary to the ICDs – it is used externally, and the electrical shocks must penetrate the chest and reach the heart.

Ventricular Tachycardia and Ventricular Fibrillation

Ventricular tachycardia and fibrillation are the two most common arrhythmia types that can occur from a sudden cardiac arrest. The automated external defibrillator can treat both heart conditions by analyzing the rhythm and administering shocks.

Cardioversion is the process of normalizing your heart rhythm. The primary purpose of automated external defibrillators is to perform successful cardioversion, increase survival chances, and reduce the risk of other impairments.

Ventricular Tachycardia

To comprehend how the automated external defibrillation process works, we must understand what a ventricular tachycardia is. This medical condition is a state of arrhythmia, or simply put, an improper heart rhythm.

Ventricular tachycardia is characterized by irregular and improper electrical signals in the lower chambers (the ventricles) of the heart and is also known as the V-Tach or VT. This medical condition can be both a cause and a result of a sudden cardiac arrest.

The main characteristics of tachycardia are a very fast heartbeat and no pulse. If you find yourself near a person experiencing a ventricular tachycardia, an AED can save a person’s life. Automated external defibrillation and administering shocks will jolt the heart back to a regular rhythm.

Additionally, automated external defibrillators have an algorithm to detect such medical conditions. The device analyzes the heartbeat and can detect ventricular tachycardia through the beat range. If the heart beats between 140 and 240 times per minute, the device recognizes it as Monomorphic Ventricular Tachycardia as a shockable rhythm and delivers a shock.

On the other hand – to get a picture of how defibrillation works – Polymorphic Ventricular Tachycardia isn’t recognized as a shockable rhythm. The AED device only tells you it isn’t a shockable rhythm, meaning you should proceed to the performance of a CPR procedure.

Ventricular Fibrillation

Ventricular Fibrillation is the arrhythmia of the lower heart chambers – when they contract rapidly and uncoordinatedly. Chest pain and erratic and irregular heartbeat are the signs that signal an upcoming fibrillation.

Ventricular fibrillation, also called V-Fib, is a deadly arrhythmia where every minute counts. Automated external defibrillation and CPR are the most effective emergency response techniques for this arrhythmia. In this case, the electrical current of the AED – through shocks – helps restore the normal heartbeat.

If AED is administered to the patient in the first three minutes after the collapse, the chances for survival can be as high as 95%. However, the defibrillation technique needs to be followed by CPR after delivering the shocks.

Below is a straightforward explanation to learn how to deliver automated external defibrillation and how the AED device works. This will help you better understand What Is Automated External Defibrillation.

Steps For Administering Automated External Defibrillation

The AED is an exquisitely simple device with incorporated algorithms and biphasic waveforms. It’s easy to use and has only a few buttons for delivering defibrillation.

You should follow the several simple steps to perform successful defibrillation. According to the Red Cross, there are seven straightforward steps to save someone’s life, and they all begin with making the correct checks and calls.

There’re certain situations when automated external defibrillation should be avoided. That’s why you start by ensuring that the person has suffered a cardiac arrest or some deadly arrhythmias. Once you’re sure, you must call the emergency services and use the defibrillator near you.

Following are the other defibrillation steps:


      • Turn the device on and see if there’re voice prompts (follow them);

      • Remove the top part of the person’s clothing and dry the chest if necessary;

      • Place the pads on the chest’s upper right and lower left side (under the armpit);

      • Connect the pad plug and the AED;

      • Analyze the heartbeat;

      • Deliver a shock if necessary;

    The defibrillator will deliver electrical current through the chest to the heart. This brief electrical shock will depolarize the cardiac muscles and enable the “heart’s natural pacemaker” – the sinus node to reestablish the normal heart rhythm.

    Some Other AED-related Rules

    Automated external defibrillation is most effective with electrical currents ranging between 100 and 360 J (Joules). Most defibrillators deliver shocks ranging between 120 – 200 J and travel between the pads – through the chest – in opposite directions.

    Furthermore, you should strictly avoid performing automated external defibrillation on conscious and breathing persons. Administering defibrillation shocks to children under the age of 8 is allowed but should be done with caution. It’s best to use pediatric defibrillators to administer pediatric shocks to children under eight and even infants.

    Even though analyzing the heart’s rhythm and the shocks can help restore the regular beat, CPR can help restore normal blood flow and oxygen levels. All relevant authorities, like the American Heart Association or the American Red Cross, advise us to proceed to CPR if the fibrillation persists after the initial shock.

    A Comparison Between Automated External and Internal Defibrillation

    Both processes work on the same principle – diagnosing arrhythmias and providing automated defibrillation. The only difference is that the internal defibrillator is implanted into the person’s body and analyzes and acts from within.

    Modern external defibrillators deliver lower-range shocks and use the biphasic waveform. This means that they range from 120 to 200 joules, unlike the monophasic defibrillators, which deliver shocks between 200 and 360 joules. ICGs provide a maximum of 80 joules, but research showed that 40-J shock is sufficient for successful defibrillation.

    All in all, there aren’t any significant differences in the effectiveness of the two types of defibrillation. No matter the defibrillation type, it must be delivered on time and with the proper electrical current power.

    AED & CPR: A Life-Saving Combination

    We’ve already mentioned the complementary importance of the CPR procedure in automated external defibrillation. However, AED is more effective in saving cardiac arrest victims when performing chest compressions.

    Patients who received AED shocks before arrival at the Emergency Medical Care had a 24% survival chance. On the contrary, when cardiac arrest victims got only chest compressions, mouth-to-mouth ventilation, or a combination of both, their survival chances were as low as 9%.

    Nonetheless, CPR and AED combined can significantly increase the overall survival rates. Two things we should remember: after each shock – a two-minute-CPR cycle and follow the voice prompt of the AED device. That’s how you administer successful defibrillation and reduce the risk of neurological impairments and death.

    Conclusion: What Is Automated External Defibrillation

    It’s more than clear that automated external defibrillation is the process of restoring the normal heart rhythm disturbed by arrhythmias like V-Tach and V-Fib. The proper use of the AED devices will help you analyze the heart and deliver electrical shocks if necessary.

    Defibrillation should be done under the right circumstances. You must be sure that the person has suffered a cardiac arrest and call 991 immediately. Then, you should proceed to defibrillation and combine it with CPR to guarantee the best possible results. Now you should have a better understanding of what is automated external defibrillation.