Understanding the Various Types of Defibrillators and How They Work
When a person is experiencing certain types of life-threatening irregular heartbeats, sending an electrical current or a counter-shock to the heart can help restore a regular heartbeat.
This process is known as defibrillation. Although the precise mechanisms are not known, this process generally depolarizes most of the heart, which ends the cardiac arrhythmia and allows the heart to re-establish a normal beat.
For over a century, scientists and doctors have observed a connection between administering electrical shocks and heart function in humans and animals. Over time, defibrillators of various forms have been invented and deployed for use, including automatic external defibrillators (AEDs), which can be used by non-medical personnel to save a life. You may be asking yourself, “What does a defibrillator look like?” Knowing the answer may make all the difference in a life or death situation.
Defibrillators are largely used to address certain types of cardiac arrhythmias:
- Pulseless ventricular tachycardia, or V-tach: Improper electrical activity in the heart’s ventricles that causes a very fast, ineffective heartbeat.
- Ventricular fibrillation, or V-fib: The ventricles don’t pump blood normally but quiver instead, leading to an irregular heartbeat.
These arrhythmias can quickly lead to serious conditions such as brain damage, heart attack and death. Defibrillators of various types can deliver the electric current needed for the heart to regain a regular rhythm.
These machines are not to be used when a victim is flat lining, despite what you may have seen in film and television. Defib machines require a shockable heart rhythm upon which to act. A flat line, also known as an asystole pattern, requires the provision of cardiopulmonary resuscitation (CPR) and a cardiac stimulant drug.
Comparing Different Types of Defib Machines
The various types of defibrillators are largely characterized by whether they’re located inside or outside of a patient’s body (internal or external), as well as whether a shock is delivered manually or automatically:
- Manual external defibrillator: Often used with an electrocardiogram, this type of machine is what is often depicted in medical TV shows. Pads are applied to the victim’s chest for delivery of the charge. These machines should only be used by trained healthcare professionals who can assess the quality of the heartbeat and determine the voltage and timing of the electrical current. These devices are found in hospitals and ambulances.
- Manual internal defibrillator: These devices send a current through paddles placed on the heart itself. They are typically used in an operating room, and on rare occasions, during open-heart procedures in the emergency room.
- Automated external defibrillator (AED): These portable devices are intended for use by laypeople who may or may not have basic CPR training. AEDs are portable and designed to detect if a heart rhythm is shockable. They can be completely automatic, delivering a current on their own, or semi-automatic, delivering a current with the press of a button. The charge delivered is preset and usually cannot be adjusted, unlike manual versions. AEDs are now often installed in public areas for general use. They improve survival chances for cardiac arrests that take place outside of hospitals when bystanders step in to intervene and administer them.
- Implantable cardioverter-defibrillator (ICD): Like pacemakers, these devices are implanted into a patient’s chest to check heart rhythm continuously and deliver shocks for critical arrhythmias. Often ICDs can differentiate between life-threatening irregular heartbeats and benign types. Many of these types of defibs also include pacemaker-type functions.
- Wearable cardioverter defibrillator: This device is an external defib typically worn as a vest by patients who are at risk of cardiac arrhythmia but may not be candidates for ICDs. It monitors continuously, delivering a shock if V-tach or V-fib is sensed.
- Internal defibrillator: This internal defib is often used during or after heart surgery, attaching directly to heart muscle.
Analyzing the Components of a Defibrillator
When it comes to understanding what a defibrillator looks like, you need to understand the basic parts. Virtually every defibrillator connects to two electrodes that are attached by a user to the victim’s body to deliver the charge. A gel that conducts electricity is used to achieve a good connection between the electrodes and the body.
Paddle electrodes are the type commonly shown on TV. They are made of metal with plastic handles and must be held in place with at least 25 pounds of pressure. They are reusable and require gel to be applied with each use.
Self-adhesive electrodes are the type commonly found with AEDs. They are single-use and come with the gel pre-applied Because of the chemical breakdown of the gel in these pads, the manufacturers cannot guarantee the pads will have enough adhesion to work correctly after a certain amount of time has passed, so they expire and must be replaced every couple of years if not used.
Operating an Automated External Defib
Of the various defibrillators, only AEDs can be used by nonmedical personnel. Most of these devices walk a user through steps using visual or audio prompts. While AED training is recommended, you may not get the opportunity before a situation arises where you need to render aid, so it’s a good idea to understand the basic steps:
- Unbutton or cut open the victim’s shirt with scissors (usually provided with the AED).
- Dry the victim’s chest with a towel, if necessary.
- Use gloves to remove any medicine patches.
- If the victim has a hairy chest, shave hair using a razor (often included with an AED).
- Adhere the pads to the victim’s chest.
- Make sure that no one is touching the victim’s body.
- Select the analyze button, if prompted. Fully automated models will do this automatically.
- If prompted, deliver a current by pressing the button. Make sure other people are standing clear first.
- Be prepared to administer CPR when directed to by the machine.
- Perform five cycles of CPR, which are approximately two minutes.
- If the victim responds to CPR, stop, and monitor for additional defibrillation.
Attending to the needs of a person suffering from arrhythmia-induced cardiac arrest usually includes CPR. It is advisable to get certified in CPR and first aid so that you can render aid quickly and assuredly.
Taking Proper Precautions
Regardless of what kind of defibrillator it is, all models make use of electrical current and can be dangerous to both the victim and the operator when the proper precautions aren’t taken. Here are some things to watch out for:
- Avoid using defibs in wet environments, as water conducts electricity. Remove all moisture from the victim’s chest to ensure that the current travels to the heart and not to surface moisture.
- Remove bras that contain metal underwire and any metal piercings. Metal is a conductor of electricity and its presence with the use of a defibrillator may lead to a fire and burns.
- Make sure that other people are not touching the victim when the current is delivered, as the body is also a conductor of electricity.
- Avoid using a defibrillator in the presence of flammable vapors or substances, as the spark generated by the electric current may result in an explosion or fire.
- Only trained medical professionals should change the amount of charge delivered by a defibrillator. Some AEDs come with an override option. You should not engage this.
- Always follow the prompts when using an AED. Again, overriding AED function should only be done by medical experts.
Being Confident When Using an AED
Uncertainty, fear of legal repercussions, and ignorance can negate the usefulness of an AEDs when the need arises. Bystanders who attempt a rescue using an AED are protected under the “Good Samaritan” laws.
These laws were put into place to encourage bystanders to deploy an AED to save a sudden cardiac arrest victim whenever possible. Taking CPR/AED training courses can help to boost your confidence while also increasing the chance of a positive outcome.
The following information will also aid in easing the fear of rescuing victims with AEDs
- You can’t accidentally shock someone with an AED. These devices are designed to only deliver a shock when absolutely necessary.
- AEDs don’t make a victim’s body jerk violently or make their limbs shake. Regardless of what you may have seen in a movie or a TV show, this doesn’t happen in real life. There may be slight movements induced by a shock at most. Remember, defib devices aren’t effective on a victim who has flatlined. Apply a shock only if directed by an AED. Don’t assume improper function based on a lack of dramatic body movements.
- You can use an AED on a victim who appears to have a pacemaker or internal defib device. Look for a lump on the upper left side of the chest near the heart to locate it. Apply the electrode pads at least 1 inch away.
- If you have to use an AED on a younger child, use pediatric pads if available. In an emergency, use an available device on infants and small children as you would on an adult. This is far more preferable to doing nothing. Keep in mind that life-threatening cardiac arrhythmias don’t improve without intervention and the resultant cardiac arrest will end in death without treatment that needs to happen.
Defibrillators like AEDs can help save lives when properly administered. It’s important to know how to recognize AEDs as well as where they’re located in public places and in the workplace. .
Consider enrolling in some formal training classes that are readily available through various organizations so that you can use an AED confidently and reliably when necessary. AEDs require certain precautions for safe operations, but it’s important to understand their intended use to avoid making a situation go from bad to worse through improper use or inaction.
You, too, can save a life, and together we can work to increase the stagnant 6% of sudden cardiac arrest survivors who survive to 50% instead.