Witnessing a cardiac arrest can be a frightening and stressful situation. Being confident in how to proceed and provide resuscitative measures is very important in helping improve the chances of survival for those who experience a cardiac arrest.
An Automatic External Defibrillator (AED) is a medical device that can be used when an individual goes into cardiac arrest. Its role is to try to return the heart to a normal sinus rhythm. It can guide a bystander through steps to attempt to resuscitate a patient and will deliver an electrical current to the person's heart if needed. AEDs are often located in public settings or buildings in hopes of providing access to defibrillation as soon as possible.
What is Cardiac Arrest?
Before we understand how to use an AED, let's first learn when to use one. Cardiac arrest occurs when there is an electrical complication with the heart that prevents it from functioning properly. This is due to a rhythm abnormality or the complete absence of a rhythm. For the heart to perfuse the body efficiently and do what it is designed to do, the electrical activity must be functioning properly, and the heart needs to be in a normal sinus rhythm that is consistent, coordinated, predictable, and within a safe rate.
There are three points to focus on when assessing whether someone is in cardiac arrest and to determine if an AED may be needed. Assess the following:
- Responsiveness: Can the individual talk or react to touch or sound?
- Breathing: Is the individual breathing?
- Pulse: Is there a pulse present? (Assess the carotid artery located to the side of the throat)
If these three functions are absent, it is safe to assume that the individual is in cardiac arrest, and it is vital to proceed with resuscitation measures. Such resuscitation measures include calling 911, locating the AED, and doing effective chest compressions.
How Does an AED Work?
An AED is a portable defibrillator that can provide an electrical current to attempt to reset the heart to a normal rhythm. Upon locating the AED, turn on the power button and follow the prompts provided. The machine will explain placing electrical pads on the bare chest of the affected person, which are used to both assess heart rhythm and to provide a shock if needed. One pad will be placed in the center of the chest, and one will be placed below the individual's left breast beneath the heart. If the AED is beingused on a child, place one pad on the child's chest and the other on the child's back.
The AED will alternate between directing chest compressions and rhythm analysis. It is important to continue doing chest compressions with as little interruption as possible until the AED provides direction to stop touching the patient. If a shock is advised, the bystander using it will be instructed to clear the patient or break physical contact, and an electrical current will be delivered to attempt to restore normal electrical heart activity. After the shock has been delivered, proceed as directed by the AED in doing chest compressions.
It is important not to touch the patient while the AED is analyzing the individual's heart rhythm. This is to prevent artifacts or interruptions in the rhythm analysis from an outside source or external movement. It is also important to ensure that no one is touching the patient when the shock is delivered for the safety of the one providing the resuscitation attempt.
Always remember to monitor the safety of any rescuers or bystanders at the scene. If there are any dangers at the scene that can be removed, do so quickly. If the circumstances surrounding the resuscitation could be dangerous to any bystanders, wait until medical assistance is available.
Special Considerations
When using an AED, there are special considerations to be aware of. If an individual is lying in water, remove them from the water. Delivering a shock in water is dangerous and can also shock the rescuer if they are in the water. Remove wet clothing and dry the individual's chest. The pads will not stick effectively when wet. Chest hair can also cause complications for pad placement. Some AED kits include a razor to remove hair quickly. Most AEDs come with two sets of pads. The rescuer can apply the first pair and quickly tear them off to remove hair. The second pair can then be placed in the hairless area. Always remember that the AED will not work appropriately if there is no direct contact with the victim's skin.
Why is Shock Not Advised?
After analyzing the heart rhythm, the AED will determine if a shock is appropriate for treatment. In some situations, the AED will report that a shock is not advised and will instruct that chest compressions continue.
Why would a shock not be advised in a cardiac arrest situation? The answer to this question is found in the type of rhythm the heart is exhibiting.
Types of Heart Rhythms
The heart not only has its physical components, which include the ventricles, atria, arteries, the superior and inferior vena cava, and valves, but it also has electrical components. The components that make up the electrical conduction system of the heart include:
- Sinus node
- AV node
- Bundle of His
- Bundle branches
- Purkinje fibers
Together, these elements form the electrical system of the heart. The electrical conduction within the heart is responsible for the coordination, rate, and rhythm of the heart. Without a properly functioning electrical system, the heart is unable to beat and contract properly to sustain the human body. When complications arise with this system, the result can be dangerous heart rhythms. In a cardiac arrest, there are only two rhythms that are considered shockable. They are pulseless ventricular tachycardia (V-tach or VT) and ventricular fibrillation (V-Fib). Both rhythms are very dangerous and life-threatening.
Pulseless Ventricular Tachycardia (VT)
Pulseless ventricular tachycardia means that the ventricles are contracting extremely fast. The average heart rate for an adult is 60-100 beats per minute. In ventricular tachycardia, the heart beats much quicker than this, and at a faster rate than is sustainable for the body. The abnormal rhythm originates within the ventricles themselves. The ventricles contract at a speed at which they are unable to adequately fill with blood before it is ejected from the heart. This rhythm produces no pulse because blood is not circulating correctly. Without a pulse, no oxygenated blood is being circulated to the rest of the tissues, organs, and systems of the body, leading to inadequate organ perfusion and ultimately death.
Ventricular Fibrillation (V-fib)
Ventricular fibrillation is another abnormal rhythm that originates within the ventricles. It is extremely dangerous, with death resulting in just minutes if not corrected. Vfib occurs when the ventricles are uncoordinated and contract out of control. Rather than contracting as they normally should, they quiver and are ultimately inefficient. This leads to poor cardiac output (the amount of blood the heart circulates) and is unsustainable for life.
Non-Shockable Rhythms
Other types of rhythms can be deciphered using an AED, but for which an electrical shock is not appropriate or indicated. These rhythms are pulseless electrical activity (PEA) and asystole. PEA is present when there is electrical activity in the heart but no mechanical response (physical contractions of the heart). Asystole, commonly referred to as flatline, is when there is no electrical or mechanical activity.
To correct these rhythms, medications, CPR, and treatment of the underlying causes are necessary for patient survival. Shocking these rhythms inappropriately can result in the heart switching to a deadly rhythm like VT or V-Fib. Proper treatment of non-shockable rhythms requires extensive medical training and knowledge. If a shock is not advised, continue chest compressions until medical personnel are available to take over care of the individual.
I'm Not a Healthcare Professional, Can I Use an AED?
AEDs are built for anyone to use, not just healthcare providers. They provide ease of use, with careful instructions for each step in the resuscitation process. It is critical that defibrillation by an AED is done as soon as possible if indicated. Studies have shown that the sooner an individual receives defibrillation, the higher the survival rate and the better the neurological outcomes. Such findings demonstrate how beneficial increased bystander education is surrounding AEDs.
Having more AEDs available in public spaces can improve cardiac arrest response time and defibrillation accessibility. Resuscitation of a cardiac arrest patient is indeed a necessary step in saving individuals. AEDs have made it possible for treatment to be accessed quickly and to be performed by those with little or no medical knowledge. Understanding how and why an AED works instills confidence in the public and those who are present during cardiac arrests.
Acknowledging the Bystander
For those who witness a cardiac arrest and participate in resuscitative measures, this can be a difficult experience to cope with, regardless of whether they are medical personnel or lay responders. As bystanders, they are not expecting to participate in such an experience, given the day or situation. While using an AED and performing CPR drastically increases survival rates, this is not always the case. There are many situations in which death occurs. This is not rare.
It is important to recognize that any and all efforts to help someone in cardiac arrest are valuable, despite the outcome. Acknowledgement of the mental and emotional health of those who participate in resuscitation efforts is something that should not be overlooked. Due to the invasive, harsh aspects of resuscitation and witnessing the reality of the situation, many who participate find themselves overwhelmed, saddened, or in emotional turmoil.
It takes great courage to care for someone whose life hangs in the balance, and one should never cast blame upon oneself for another's death in this situation. Help should be sought if bystanders are having difficulty coping with the experience.
Conclusion
AEDs provide quick and efficient life-saving measures for those who experience cardiac arrest. Having knowledge of how to use them can instill confidence in those who attempt to resuscitate individuals who are in cardiac arrest. Not all rhythms experienced during cardiac arrest warrant defibrillation, but an AED can determine which kind of care is required through rhythm analysis.
About the Author:
Rachel Pugmire is a registered nurse and freelance writer. She received her Bachelor of Science in Nursing in 2018, with a minor in gerontology. Her areas of expertise include emergency medicine, pediatrics, and pharmaceutical clinical trials. Medical writing has given her a platform to do what she is passionate about, which is educating patients, their families, and other healthcare professionals.
Rachel is an independent contributor to CEUfast's Nursing Blog Program. Please note that the views, thoughts, and opinions expressed in this blog post are solely those of the independent contributor and do not necessarily represent those of CEUfast. This blog post is not medical advice. Always consult with your personal healthcare provider for any health-related questions or concerns.
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