AED Usage on Adults: Defibrillation for Cardiac Arrest Emergencies

Last updated:
June 2, 2023

In the critical moments following a sudden cardiac arrest (SCA), swift and appropriate intervention can make all the difference between life and death. Automated External Defibrillators (AEDs) have emerged as indispensable tools in these emergency situations, providing timely electrical shocks to restore the heart's normal rhythm. This article aims to shed light on the vital role AEDs play in adult cardiac arrest scenarios, emphasizing their importance and offering comprehensive guidance on their usage for adults.


What is an AED?

An AED is a portable, lifesaving device that shocks the heart to restore the normal heart rhythm. It is designed to be used by anyone, regardless of their medical training, and can be found in public places such as airports, sports stadiums, and shopping malls.

The use of an AED is simple and straightforward. The device provides voice and visual instructions that guide the user through the process, and once activated, it analyzes the victim's heart rhythm to determine if a shock is needed. If a shock is necessary, the device will automatically deliver it at the appropriate time.

Studies have shown that using an AED within the first few minutes of a cardiac arrest can increase the chances of survival by up to 75%. This is because the sooner the heart can be restored to its normal rhythm, the less damage will occur to the brain and other vital organs.


Why are AEDs Important in Adult Cardiac Arrest?

Sudden cardiac arrest (SCA) is a leading cause of death worldwide, claiming millions of lives yearly. It is a medical emergency that occurs when the heart suddenly stops beating, and without immediate intervention, it can lead to brain damage or even death within minutes. However, using an Automated External Defibrillator (AED) can significantly increase the chances of survival for cardiac arrest victims.

AEDs offer a critical advantage by providing rapid defibrillation, a key factor in successfully restarting the heart. Promptly delivering an electric shock within the early stages of cardiac arrest can help restore the heart's normal rhythm, allowing oxygenated blood to circulate throughout the body once again. This timely intervention significantly enhances the chances of survival and minimizes the risk of long-term complications.


What are the Benefits of using AEDs?

Using Automated External Defibrillators (AEDs) on adults in cardiac arrest situations offers numerous benefits, greatly increasing the chances of survival. Here are some key advantages:

  1. Rapid Response: AEDs are designed to be easily accessible and user-friendly, allowing bystanders and trained individuals to initiate immediate life-saving measures. Time is critical in cardiac arrest, and AEDs enable swift action, significantly reducing the delay between collapse and defibrillation.
  2. Simplicity and Guidance: AEDs are equipped with clear audio and visual prompts, guiding users step-by-step through the defibrillation process. These prompts ensure proper electrode placement and timing of the shocks, making AEDs effective even for those without medical training.
  3. Automated Analysis: AEDs have built-in technology that analyzes the heart's rhythm and determines whether a shock is necessary. This automated analysis ensures accurate decision-making, reducing the risk of unnecessary shocks and minimizing potential harm.
  4. Restoring Normal Heart Rhythm: The primary function of AEDs is to deliver an electric shock to the heart, known as defibrillation. This shock helps to reset the heart's electrical system, restoring a normal rhythm and allowing the heart to effectively pump blood to vital organs.
  5. Increased Chance of Survival: Early defibrillation is crucial for survival in cardiac arrest. Studies have consistently shown that using AEDs within the first few minutes of cardiac arrest can significantly increase the chances of survival, often doubling or tripling the likelihood compared to delayed defibrillation.
  6. Availability in Public Spaces: AEDs are increasingly available in public spaces, workplaces, and community settings. Their widespread presence ensures that immediate life-saving intervention can be initiated before emergency medical services arrive, enhancing the overall chain of survival.
  7. Portability and Accessibility: AEDs are designed to be lightweight, portable, and easily transportable. This mobility allows for quick deployment in various settings, including homes, offices, sports arenas, and public gatherings, ensuring timely access to defibrillation when needed.
  8. Risk Reduction: AEDs help minimize the risk of brain damage and other serious complications resulting from prolonged cardiac arrest. By restoring normal heart function promptly, AEDs contribute to preserving the overall health and well-being of cardiac arrest victims.


Who Can Use an AED on Adults?

AEDs are designed to be used by anyone, regardless of their medical training. The AED devices are designed with clear instructions and user-friendly interfaces, often featuring audio and visual prompts that guide the user through each step of the process. These prompts provide guidance on proper electrode placement, delivering shocks, and performing CPR. making them easy to use in emergency situations.


When Should an AED be Used on an Adult?

An AED should be used on an adult who is unresponsive, not breathing normally, and does not have a detectable pulse. It is important to note that an AED should not be used on a cardiac arrest patient who has a pulse, as it can cause more harm than good. The AED is designed to analyze the heart rhythm and deliver a shock only if necessary. Therefore, it is important to follow the instructions provided by the AED and not use it on someone who does not meet the criteria for its use.

What are the step-by-step instructions for using an AED on an adult?

Using an AED on an adult in a cardiac arrest situation involves several steps to ensure proper and effective usage. Here is a detailed guide on how to use an AED on an adult:

Step 1: Turn on the AED and follow the voice prompts

Switch on the AED, which is typically done by pressing the power button. The device will then provide clear voice prompts to guide you through each step of the process.


Step 2: Expose the victim's chest

Ensure the victim's chest is exposed by removing any clothing or obstructions. If the chest is wet, quickly dry it to ensure good electrode pad adhesion.


Step 3: Remove medication patches

If the victim has any medication patches on their chest, such as nitroglycerin patches, carefully remove them before applying the electrode pads.


Step 4: Attach the electrode pads to the victim's bare chest

Proper placement of AED pads on an adult's chest is crucial for effective defibrillation. Take the electrode pads from the AED and remove the backing, exposing the adhesive side. AED pads are typically labeled as "upper right" and "lower left." Look for these labels or indicators on the pads themselves. If not labeled, examine the illustrations on the pads, which often depict their correct placement.


How should the AED pads be placed into the chest of an adult?

  • Place the 1st pad firmly on the victim's upper right chest, just below the collarbone. Center the pad over the breastbone, aligning it horizontally with the shoulder.
  • Place the 2nd pad firmly on the victim's lower left side, slightly below the armpit. Align the pad horizontally with the center of the victim's chest, beneath the left nipple area.
  • Ensure the pads are securely attached to the victim's chest without any wrinkles or air pockets. Press down firmly on the pads to ensure good adhesion.


Step 5: Clear the victim and allow the AED to analyze the heart rhythm

Ensure no one is touching the victim, including yourself, and press the "analyze" or "analyze rhythm" button on the AED. The device will then analyze the victim's heart rhythm through the electrode pads. It is important to avoid touching the victim during this analysis.

  • If a shock is indicated, it will provide clear instructions to deliver the shock. Make sure no one is in contact with the victim, including yourself, and press the shock button as directed. Some AEDs may deliver the shock automatically without the need for a button press.
  • If no shock is advised, perform Cardiopulmonary Resuscitation (CPR)  by pressing hard and fast in the center of the victim's chest, following the recommended compression depth and rate.


Step 6: Continue following the AED's prompts and performing CPR until emergency medical services (EMS) arrive

Follow the AED's voice prompts for further instructions, which may include additional shock deliveries or switching to CPR. Continue providing CPR until trained medical personnel, such as paramedics, arrive and take over the care of the victim.


Remember that an AED is just one part of the response to SCA is important. It should be used in conjunction with Cardiopulmonary Resuscitation and emergency medical services. The American Heart Association recommends that bystanders begin Cardiopulmonary Resuscitation immediately and use an AED as soon as possible.

Related Article:
Adult CPR: How to Give CPR to an Adult

What precautions should be taken when applying AED pads over body hair or jewelry?

When applying AED pads over body hair, it is important to remove excessive hair or shave the area for better pad adhesion. If the victim is wearing jewelry, it should be removed or moved away from the pad placement area to avoid interference with the electrical current and potential discomfort or burns. These precautions ensure optimal contact and effectiveness when using an AED.


Special Considerations for Specific Adult Populations

While AEDs are designed to be user-friendly and effective across various populations, it is important to consider these unique considerations and adapt the application of AEDs accordingly to provide the best possible care in specific adult populations.


Pregnant Women

When using an AED on a pregnant woman in cardiac arrest, the main goal is to ensure the safety of both the mother and the fetus. The AED pads should be placed in the standard positions on the chest, avoiding the abdomen. If possible, care providers should manually displace the uterus to the left to minimize interference with the AED pads. Additionally, it is important to consider that pregnant women may have different CPR techniques due to changes in body anatomy and physiology.



The elderly population may have specific considerations when using AEDs. Skin conditions such as thin skin or frailty may require extra care during pad placement to ensure good adhesion. Additionally, older adults may have underlying health conditions or limitations that could affect the effectiveness of CPR and defibrillation. Adjustments should be made to provide appropriate pressure during chest compressions, and the AED should be used promptly to increase the chances of survival.


Individuals with Underlying Health Conditions

People with underlying health conditions, such as pacemakers, implantable cardioverter-defibrillators (ICDs), or other cardiac devices, may still benefit from the use of an AED. However, caution should be exercised to avoid placing the AED pads directly over or near these devices. If possible, the pads should be placed at least 1-2 inches away from the device to prevent interference. If uncertain about the location of such devices, it is generally safe to proceed with AED usage.


What are the Common Misconceptions about AEDs?

Despite the benefits of AEDs, some misconceptions exist about their use. One of the most common misconceptions is that AEDs can cause harm to the victim. However, research has shown that the benefits of AED use far outweigh any potential risks. AEDs are designed to only deliver a shock when necessary and have built-in safety features to prevent accidental discharge.

In conclusion, using an AED or Automated External Defibrillator is a simple and effective way to save lives in the event of sudden cardiac arrest. AEDs are easy to use, affordable, and accessible, making them an essential tool in any public space. Educating ourselves and others about the importance of AEDs can help increase survival rates and make our communities safer for everyone.

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