Defibrillator FAQs: A Comprehensive Guide

Every medical drama on television seems to have a scene where a handsome but frantic doctor calls out, "Charge to 300! Clear," before forcing a jolt of electricity into a seemingly lifeless body. In reality, this scene plays out in hospitals across the country as real-life physicians use a device called a defibrillator to save the life of a person experiencing cardiac arrest. Click Here to Purchase New, Used, and Refurbished Defibrillators

Who invented the defibrillator?

The external defibrillator was invented by an electrical engineer named William Kouwenhoven in 1930. As a student at the Johns Hopkins University College of Engineering, Kouwenhoven studied the effects of electrical shock on the human heart and invented a device to "jump start" the heart. Originally, the defibrillator was tested on dogs until it was determined to be safe for human use. That day came in 1947 when Claude Beck at Case Western University theorized that the device could be used during ventricular fibrillation to prevent a good heart from stopping. It was first used on a 14-year-old boy whose heart when into fibrillation following a procedure. Paddles were applied directly to the young man's heart, restarting his heart and starting him on his path to recovery. Nine years later, a much more powerful model was created to perform the first external defibrillation.
old defibrillator 1940's Style Defibrillator
Over the years, the defibrillator changed as the technology evolved. However, the next big development in defibrillation was the advent of the Automated External Defibrillator in 1978. This device not only included a self-contained process and instructions for use by any doctor or nurse in any clinic or hospital, but it also paved the way for the evolution of today's AEDs.

What does defibrillation do?

A heart that beats normally does so in a rhythmic fashion, allowing blood to flow into and out of the heart via muscle contraction. During cardiac arrest, the bottom chambers of the heart begin quivering rather than beating normally, preventing blood from flowing the way it should. This condition, known as ventricular fibrillation, is fatal in most patients but can be treated with a targeted electrical shock to the heart. In essence, the heart is restarted and allowed to resume its normal rhythm.
Physio-Control LIFEPAK 12 An example of a defibrillator

What happens to the heart when it is defibrillated?

During defibrillation, two electrodes are placed on the chest that delivers the electrical shock. The voltage travels throughout the entire body, with the majority of the voltage traveling from electrode to electrode, directly through the heart. As the electricity passes through the heart muscles, it forces a strong contraction then a short rest period, allowing the muscle to begin contracting normally.

How many volts are used in defibrillation?

The number of volts used in defibrillation depends on the type of defibrillator being deployed. An Automated External Defibrillator (AED) that is commonly found in gyms, schools, sporting arenas, or airports delivers a 3000-volt charge in 0.001 seconds. That is roughly enough electricity to power a 100-watt light bulb for 23 seconds. Biphasic defibrillators used in hospitals will deliver electrical charges in pulses, mimicking the beating of a heart. Pacemakers and other internal defibrillators use a much lower voltage to stimulate heart contractions as they are in direct contact with the heart.

Who needs a defibrillator?

Defibrillation is one of the most effective ways to restart a heart that is beating erratically. The most common arrhythmias seen in cardiac arrest are ventricular fibrillation and ventricular tachycardia. In ventricular fibrillation, the lower chambers of the heart quiver rather than beat as they normally do, preventing blood from flowing into and out of the heart the way it should. Once oxygenated blood is prevented from reaching the brain, the person can die within 5 minutes of experiencing ventricular fibrillation. Ventricular tachycardia is a very fast beating of the ventricles that can last for a few seconds or few minutes before the heart stops entirely. In both cases, the use of a defibrillator can increase the likelihood of survival by restoring the heart's normal rhythm.

Why is early defibrillation important?

In the case of cardiac arrest, time is critical. For every minute that goes by without CPR or defibrillation, the chances of survival decrease by seven to ten percent. While it is tempting for non-medical bystanders to call 9-1-1 and wait for an ambulance, nine out of ten people who experience cardiac arrest will not survive the wait for emergency medical personnel to arrive on the scene. However, early defibrillation, even with an AED in the hands of an untrained bystander, can increase the likelihood of survival. While many are reluctant to begin CPR due to a lack of training or experience, an AED's easy-to-use design allows even the most reluctant of witness to provide immediate medical attention. That likelihood of survival of a cardiac arrest nearly doubles when a person experiences the in a hospital where trained medical personnel has different defibrillation options at their disposal. Whether it is a doctor who begins pacing the heart with a biphasic defibrillator that mimics the human heartbeat, or the placement of an internal pacemaker that allows the heart to receive electrical shocks when needed, without the intervention of a user or physician, defibrillation options are varied and largely dependent on the skill of the doctor and needs of the patient.

When should a defibrillator be used? When should it not be used?

A defibrillator should be used any time a person is experiencing cardiac arrest. However, an AED is only approved for use on children and adults over the age of eight. Pediatric electrodes are available that reduce the voltage that is allowed to travel into the child's body and should be used on children between one and eight years of age. An AED should not be used on children under the age of one, but external defibrillators found in hospitals can be used by medical professionals on children of any age. when not to use an aed The only times a defibrillator is not indicated in patients who are over eight years of age is when there is a safety concern. If the patient is lying in water, or if rain is falling on the patient, they should be moved to a dry location and dried off before using an AED. Extra care should be taken for patients laying on a metal surface to keep those aiding the patient safe. Likewise, an AED is less effective in patients who have excessive body hair and measures should be taken to rapidly shave the person's chest before attaching the electrode pads. Many AEDs come equipped with a basic razor for such a purpose.

Who can use a defibrillator?

AEDs were designed with the layperson in mind. From an internal sensor that can track a patient's heartbeat to pictorial instructions for electrode placement and shock administration, the AED was engineered to be used in non-hospital settings by non-medical persons. Anyone who is calm enough to follow verbal and pictorial instructions can operate an AED.
paramedic using defibrillator Only medical professionals should operate an external defibrillator
On the other hand, the manual external defibrillator, internal defibrillator, pacemaker, and biphasic defibrillators were created for use in hospital and clinical settings where trained medical professionals are able to correctly place or use them. These intricate pieces of machinery not only create a variety of electrical stimuli, they often have self-contained monitoring systems that allow doctors and nurses to see more than just a patient's heart rate. From blood oxygen content to pulse rate, to some other data points, these defibrillators are much more sophisticated than their AED counterparts.

Where do you place the defibrillator pads? How do you know when to administer the shock?

Defibrillation Electrode Position Image Author: PhilippN
How do you use a defibrillator? Fortunately, AEDs are designed to give you step-by-step verbal instructions. Not only will you see prompts on the screen, but you will also hear voice prompts. First, expose the person's chest and ensure it is dry. The AED is equipped with sticky pads called electrodes that have sensors inside to detect the patient's heart rate and administer the electrical shock. The AED's instructions will have pictures for how to expose the sticky surface and where to place the electrodes. One pad is placed on the right center of the chest, just above the nipple. The second pad is placed slightly below the nipple on the left side of the ribcage. This allows electricity to pass between electrodes, forcing the heart to contract. The AED will give a voice prompt when it is ready to administer the shock and advise all bystanders to stand clear of the person. Once the shock has been administered, the sensors in the electrodes will read the person's heart rate and advise when it is time to administer a second shock. It is important for bystanders to administer CPR during the AED set up and stand clear of the person when the shock is being administered.

Why should you own a defibrillator?

Manual external and internal defibrillators are not designed for home use. However, the advent of the AED has made life-saving technology available for every setting. From airports to retail stores, schools to sporting arenas, AEDs have begun appearing all over the country. In reality, there should be an AED any place where people gather. Every year more than 350,000 people will experience cardiac arrest in the US alone. Because the condition is fatal if left untreated for as little as five minutes, it is important to mitigate the risk by having AEDs readily available to the general public. There is some reluctance amongst small businesses to purchase and have AEDs available for use. In a litigious society, opening themselves up to potential lawsuits over a failed attempt to save a person's life can quickly shutter the doors. Fortunately, the federal Cardiac Arrest Liability Law limits the liability of a person who attempts to use an AED to save someone's life. Since the law was passed in 2000, all 50 states and the District of Columbia have added AED use to their Good Samaritan Laws. When an AED is made accessible, coupled with adequate training for employees of the establishment, the business is protected from liability in the event any lifesaving attempts are unsuccessful. Another factor preventing AEDs from being placed in more public spaces is cost. AEDs are expensive pieces of highly technical equipment. However, refurbished AED defibrillators are available making it possible for these lifesaving machines to be included in more locations. Click HERE to Learn More About New vs Used AED Defibrillators.

Where do you buy a defibrillator?

Medical equipment supply stores carry AEDs for purchase by the general public. Look for a store that offers phone consultations with professionals who can recommend an AED that fits your needs, storage capabilities and budget. With periodic servicing and replacement of electrode pads, an AED can be expected to last five to eight years making it a long-term investment into the health and well-being of others. If cost is holding you back from purchasing a potentially life-saving piece of equipment, many medical equipment stores offer refurbished models that have been thoroughly tested, inspected and configured for use. In many cases, these models have never been used, but are rather traded in for credit toward newer models. They can even be purchased with an optional extended parts and labor warranty to cover any malfunctions that may occur. In purchasing a refurbished AED, the trade-off is often longevity. With an expected lifespan of five to eight years for a new model, many refurbished models can last three to five years or possibly longer if properly maintained. Manual external defibrillators can also be purchased by medical equipment supply stores. It is important to discuss your hospital or clinic needs before purchasing to ensure the model you have selected will enable personnel to perform their jobs to the fullest of their abilities. Refurbished manual external defibrillators are also available. These models have also been tested, calibrated and are ready for use right out of the box. To discuss your AED needs with a qualified customer service representative or to learn more about the types of defibrillators that are available for your home, business, clinic, or hospital, contact One Beat Medical.

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