Understanding How an AED Works
Today’s technology is truly amazing.
The accomplishments that humans have made in the last five hundred years, and especially the last 100 years, could never have been imagined to the humans who were beginning to discover exploration across the oceans 600 years ago. Yet, those people spoke the same languages and wore many of the same fabrics.
It really makes one wonder how people were able to gather so much information so quickly to get where we are today. For example, how did people figure out the inner workings of the human body and discover it had its own electricity?
Because of these discoveries and exceptional minds, technology has lent itself to life saving inventions. Doctors can revive people who are on their death beds. They can move a heart from one body to another. They can even revive someone with an automated external defibrillator (AED). But, can a defibrillator restart a stopped heart?
If you go by what you’ve probably seen on many television shows and movies, then your answer would be “yes it can.” What you may not realized, however, is that television show are merely unrealistic dramatizations when it comes to using AEDs to revive people.
Can a Defibrillator Restart a Stopped Heart?
When the heart stops beating due to sudden cardiac arrest(SCA), resulting in a cardiac flatline, the flatline represents a lack of electrical activity in the heart. That electrical activity is one of the many keys necessary to a person’s survival. Much like a car needs a battery to start, a person needs an electric signal to function. Once a person’s heart has stopped beating, it is no longer contracting and pumping blood throughout the body to major organs.
A person in this condition will not benefit from an AED that delivers an electrical shock. Instead, the victim will need cardiopulmonary resuscitation (CPR) to keep their blood and oxygen flowing. EMS would follow this with an injection of a high dose type of adrenaline. A shock from an AED would actually be harmful in this case. Thankfully, AEDs are intelligent enough that they will not deliver a shock, knowing when one is not necessary, as in this case.
The only situations in which an AED is necessary is when the heart is experiencing some type of arrhythmia or erratic heartbeat. These can lead to sudden cardiac arrest (SCA) in extreme cases, though not all arrhythmias lead to such a serious event.
An AED will not bring someone back from a bad car accident or revive someone who has fallen from a building unless, in both of these situations, the person was still breathing before experiencing a sudden cardiac arrest episode.
It’s natural for a healthy person to experience arrhythmias occasionally. If they become regular and interrupt a person’s daily life, then it would be wise to see a physician who can inspect the functioning of the heart to make a diagnosis.
The goal of an AED is to reset the heart when it gets caught in an arrhythmia. This is achieved by sending it electric shocks that will interrupt the chaotic rhythm. The interruption ideally causes the heart to go back to beating at a normal pace and rhythm. If there is no beat, irregular or not, shocking the heart will not benefit the patient and the AED will not deliver one.
How Does an AED Work?
You now know that AEDs send electricity to the heart, which is known as defibrillation. But, where does this electricity in the heart reside and why does a heart rhythm become abnormal?
The defibrillator stops fibrillation, the condition in which the heart is experiencing arrhythmias and erratic beating. It does this by sending over 300 joules of electricity through the heart. This is called electrical cardioversion.
Electrical cardioversion is extremely effective during an emergency; however, it is only a temporary solution. The underlying condition that caused the arrhythmia will need to be treated to ensure the fibrillation does not return.
In a healthy heart, a group of cardiac muscle cells known as the cardiac conduction system are responsible for sending an electrical signal to the heart. These signals cause the heart to beat. The cardiac conduction system starts its work in the right atrium, which is an upper chamber, and the signal is sent down to the ventricles, which are the lower chambers. The signal sent through the heart by the cardiac conduction system causes the heart to contract in an organized rhythm.
The signal is interrupted when the heart starts to beat fast and the chambers don’t have time to fill with blood between contractions, or beats. This causes the body to become deprived of its normal blood supply, which is why the person experiencing an arrhythmia starts to feel faint.
Arrhythmias can have many causes, including heart disease, stress, substance abuse, or scarring from prior heart attacks. Arrhythmias are dangerous because when your blood is not pumping properly, the result can be a heart attack, a stroke or even worse, sudden cardiac arrest.
During defibrillation, the heart is stopped long enough to allow the contractions to reset. The large pulses of energy released by the defibrillator come from a built-in battery. This energy is sent down the two wires attached to the device which are capped off by paddles.It’s important to place the paddles in the correct positions. One paddle should be located above and left of the heart or on the lower right of the heart. The second paddle should be placed in front of the heart, which would be on top from the perspective of the person placing the pads. These placements will ensure the electricity reaches the part of the heart causing the fibrillation.
Can a Defibrillator Be Used on Anyone?
Though many people don’t notice them, defibrillators are everywhere. They’re in public buildings and schools, offices and churches. Even though they may not be legally mandated, it’s always wise to have them available, especially when the building sees a high amount of foot traffic.
Anyone can use a defibrillator on a person who is experiencing a cardiac episode. Defibrillators require no training as they instruct the user on every step. The only knowledge the user needs to have is to remove the defibrillator from the wall in the public area where it is kept when they suspect someone of having a cardiac emergency.
A defibrillator should not be used on a person who is suffering from a heart attack. A hard attack is not an electrical issue, it’s an issue with clogged arteries and the blood supply not being able to reach the heart.
During a heart attack, a person experiences pain and should still be able to respond. During cardiac arrest, the person is not responding and may not be breathing. So, if the person can talk to you and tell you where they are experiencing pain, then it’s likely a heart attack and defibrillation won’t help them.
The nice thing about AEDs is when you place the paddles on the person’s chest, the defibrillator will analyze the person’s heartbeat. If the heart does not appear to be experiencing an issue related to the heart’s rhythm, then it will not tell you to shock the person.
Children over age 8 can be treated with a standard AED. For children ages 1 to 8, the American Heart Association recommends the pediatric attenuated pads that are offered separately with many AED units.
Defibrillators can also be used on a person who has been implanted with a pacemaker. The pacemaker will be identifiable as a bulge under the skin above the left chest. When attaching the defibrillator pads, do not place them directly over the pacemaker, as this will likely interrupt the flow of electricity needed for the heart. Instead, place the pad a few inches under the location of the pacemaker.
Can Anyone Purchase a Defibrillator?
An AED purchase requires a prescription, with the exception of one particular model if purchased for home use only. AEDs are manufactured and sold under specific FDA guidelines and federal law requires a prescription.
However, most AED vendors will provide this along with your purchase, making it easy to acquire. It should be expected that as the population continues to age, it will become more common for households to equip themselves with these life-saving devices.
AED USA offers many different models of defibrillators, including mobile options that can be carried with the person who is at risk of experiencing a cardiac event. We can also answer any questions regarding AEDs and help you find the right one for your specific needs.
AEDs are a simple, yet amazing, example of human innovation. Without them, numerous people wouldn’t be alive today. Thankfully, those people are here to attest to the miraculous intervention of defibrillator technology. Educate yourself on AEDs so that you will be prepared to save an SCA victim’s life.