Should You Perform CPR Before or After an AED?

During emergencies that involve heart issues or respiratory distress, timely intervention with precise intent is what often determines whether or not the victim will survive. During such emergencies, the go-to methods for keeping someone alive until emergency medical services arrive are cardiopulmonary resuscitation (CPR) and the use of an automated external defibrillator (AED). Both are very effective when applied correctly, driving the odds of survival very high.

But when faced with an emergency that requires such techniques, should you perform CPR before or after using an AED? There is a sequence of events here, and depending on the type of emergency, different approaches may be required. Let’s explore the relationship between CPR and AED interventions further, focusing on the timing and order of their application.

The Gist Of Sudden Cardiac Arrest Events

Before delving into the timing of CPR and AED use, it is essential to understand what a cardiac arrest is and what it does. A sudden cardiac arrest occurs when the heart stops beating without a prior warning or starts to beat irregularly, thus becoming inefficient at moving blood around the body. Both these states are considered emergencies, and life-saving measures are mandatory to help the victim get through the event.

This life-threatening event can happen to anyone, no matter their fitness level, age, or pre-existing heart conditions. Lots of factors impact the occurrence of cardiac arrest, like smoking, obesity, lack of physical activity, dehydration, low potassium levels, etc.

You should also know that cardiac arrest is not the same as a heart attack. A heart attack occurs when one of the arterial blood vessels that supply the heart with blood (and thus, oxygen and nutrients) gets blocked, effectively starving the heart.

A cardiac arrest, on the other hand, is a disruption in the heart’s electrical system, which dictates the working rhythm of the organ. This electrical impulse disruption results in a flickering state of the heart’s walls, as opposed to strong contractions, which makes it ineffective in pumping blood.

Why CPR Matters

Cardiopulmonary resuscitation, commonly known as CPR, is a critical first aid technique used to remedy two key aspects of a failing body: maintaining blood flow and providing oxygen to vital organs. CPR achieves this through a combination of two potent techniques in the form of chest compressions and rescue breaths. It is supposed to keep the person alive until medics get to the scene.

From a physiological standpoint, CPR helps circulate oxygenated blood to the brain and other organs, preventing irreversible damage and drastically improving the victim’s chances of survival and post-emergency recovery. As statistics show, promptly and correctly administered CPR can double or even triple a person’s chances of surviving sudden cardiac arrest, a heart attack, or a major respiratory distress event.

The Role of an AED in Emergencies

An automated external defibrillator (AED) is a portable device you would use to shock the heart back into rhythm. While its role is clear, its use is somewhat different than most expect.

Namely, an AED can’t nudge the heart back into regular rhythm when the chamber walls are fibrillating or flickering. Instead, an AED does a “hard reset” of sorts, delivering a powerful electrical shock to the heart, which completely stops the heart’s failing electrical system for a short time. This successfully restores normal rhythm, although it may not work immediately upon the first attempt.

AEDs also analyze the heart’s rhythm and help determine whether an electric shock is necessary, and if it is, it tells you when to deliver it and how strong it should be. AEDs are user-friendly, and anyone can operate one with minimal or no training. They are either fully automated or help guide you through visual and audible instructions.

The AED plays a crucial role in the treatment of sudden cardiac arrest as it is the only device capable of delivering a reset-inducing electrical shock to the heart. Used together with CPR techniques, this duo of first aid protocols often determines whether or not a victim survives. Research indicates that administering defibrillation early or within the first few minutes of a cardiac event can improve survival rates by as much as 49–75%.

Is it Best to Perform CPR Before or After an AED?

Let’s address the key question we set out to answer today: should you perform CPR before or after an AED? The answer is not a simple “yes or no” one, as the ideal sequence depends on plenty of factors, like the availability of an AED, to begin with.

First of all, you need to recognize what you are dealing with. In cases of cardiac arrest, there is an evident absence of heart sounds and a pulse, which is an indication to use an AED in conjunction with CPR. In the case of respiratory failure, the chest does not move, and no breath can be felt from the person’s nose. Such an event does not require an AED unless the heart has also stopped, which is bound to happen quite fast after the lungs stop performing.

In situations where an AED is immediately accessible, it is recommended to retrieve the AED and use it right away. In a scenario where multiple people are present around the victim, one person should begin CPR immediately, starting with chest compressions, while another goes to retrieve the AED. As mentioned before, these first few minutes are crucial.

So, unless an AED is within the reach of your hand, starting CPR is usually the first step. Once an AED is in place, it will analyze the heart’s rhythm and tell you what to do. You should follow the device’s instructions and deliver a shock if prompted. Remember to resume CPR afterward, leaving the AED’s pads in place, as the device might prompt you to use it again.

The only time this is not true is when you have a drowning victim. Then, you would start a round of CPR with rescue breaths as opposed to chest compressions. An AED in such a situation can help restore the heart’s rhythm, but delivering oxygen to the lungs is the more pressing matter. The water involved is also important to consider as you deliver shocks. It won’t affect the AED but might shock you or a bystander if you do not move away before administering the shock.

While the specific sequence of CPR and AED use may vary based on the circumstances, the general principle is to start CPR immediately and use an AED as soon as it becomes available and as often as the device indicates once activated.

The Importance of Training and Certification

The key takeaway from understanding the sequence of CPR and AED use is the importance of early intervention. Time is of the essence when dealing with sudden cardiac arrest or respiratory failure, and every second counts. Quick initiation of CPR will help maintain blood flow and oxygenation, preserving vital organ function until an AED becomes available. Once you acquire one, it can work in conjunction with CPR, as per the instructions delivered by the AED.

Early defibrillation with an AED is crucial in restoring the heart’s normal rhythm and stabilizing the victim. The sooner a shock is delivered, the likelier you are to resuscitate the victim.

To effectively respond to such life-threatening emergencies, you should be prepared and trained in CPR techniques and AED use. CPR training and certification will provide you with the skills to perform chest compressions and rescue breaths effectively and confidently.

Training in AED use is equally important. These devices are designed to be user-friendly, providing clear audio and visual instructions to guide you through the entire process, from where and how to place the pads, to delivering shocks. However, familiarizing yourself with the operation of an AED and understanding its prompts can significantly enhance your ability to respond in an emergency.

Also, remember that refresher courses are equally important to the original certification sessions. They help you stay sharp with your acquired skills and deliver all the new advancements in CPR and AED use, further streamlining the process and increasing its effectiveness.


When faced with sudden cardiac arrest, the timing of administering CPR and AED use is critical. While the ideal sequence is to use an AED first, if one is immediately accessible, CPR will take the lead in most cases. Regardless, the important thing is to start administering help as soon as possible, sticking to CPR protocols. As an AED becomes available, you’ll be using both methods to try and keep the victim alive until professionals arrive.

So, when wondering should you perform CPR before or after an AED, it is essential to remember that you must start as soon as possible, possibly with CPR, while someone gets the AED. Being prepared and adequately trained in CPR and AED use can help tremendously. So, do not delay your CPR certification any longer, and contact us immediately to enroll in one of our many different CPR and AED courses!