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Defibrillator Joules Volts

Victims of cardiac arrest are often treated with Cardiopulmonary Resuscitation (CPR) by applying chest compressions as well as artificial breaths but defibrillation is an extremely important piece to the chain of survival with an SCA victim.

With a suspected Sudden Cardiac Arrest (SCA) event, CPR is almost always applied 100% of the time. A defibrillator applies a shock to a victim about 50% of the time because not all events are shockable. If for example, a person is suffering from a heart attack that is not often electrical in nature, an AED will not benefit the victim. Modern Defibrillators are a bridge between life and death if the victim does suffer from a shockable heart rhythm.

To maximize a person’s chance of survival, you should provide a high volt shock to the heart to bring it back to the proper rhythm. For this purpose, automated defibrillators (AEDs) are used. Before using a portable external defibrillator device, you need to know how it works. Read along to dig deeper into all the details about Defibrillators!

What is an automated external defibrillator?

The wellness of the human heart depends upon small amounts of electricity that fire in the heart triggering contractions and relaxations of the heart muscle. This small amount of electricity is delivered or provided by the Sinoatrial Node often referred to as the SA node.

What is an automated external defibrillator

A sinoatrial node is a group of pacemaker cells found in the right atrial wall of the heart’s right atrium. The heart’s electrical conduction system is made up of specialized cells that can generate an electrical impulse on their own and induce the heart to contract.

The sinoatrial node acts as a peacemaker for your body’s heart rate. This tiny amount of electricity plays a vital role in the respiratory system. The electricity sends signals to the upper chamber of the heart to pump oxygen-less blood to the lungs.

Oxygen-deprived blood becomes oxygenated in the lungs. Then, electric current from the SA node directs (or signals) the lower chambers of the heart to pump the oxygenated blood throughout the body. An electric current repeats this process in order for the heart to maintain its natural rhythm (in other words a normal heartbeat).

Certain health issues like high stress, or other risk factors may disturb the heart’s normal rhythm resulting in arrhythmia and fibrillation. Arrhythmia is the disturbance in the rhythm of the heart that causes the heart to pump irregularly. In contrast, fibrillation is another disturbance in heart rate that causes the heart to quiver instead of pumping. Both arrhythmia and fibrillation can adversely affect the health of a patient and may even prove fatal.

Defibrillators are used to revive the normal heartbeat. AEDs were designed in such a way that they can quickly treat heart problems like arrhythmia and fibrillation, delivering a controlled amount of electric shock through the heart from the chest, and constantly monitor the results. If successful the AEDs electrical shock brings back or restores the normal rhythm of the heart.

How does an AED work?

Defibrillators are available in a variety of styles. Automated External Defibrillators (AEDs), which may be found in many public places, are designed to treat victims of sudden cardiac arrest. In an emergency, even an untrained bystander can use an AED to save a life.

How does an AED work?

Portable defibrillators can help save lives among people with a high risk of deadly arrhythmia. Implantable cardioverter defibrillators (ICDs), which is surgically implanted inside the body is considered an internal defibrillator. Wearable cardioverter defibrillators (WCDs), which rest on the body, are both considered defibrillators. For this blog post, we will focus on AEDs and the number of joules they produce to save a victim of SCA.

AEDs are categorized into two categories. A manual defibrillator (semi-automatic) and an automated (fully automatic) defibrillator. The only distinction between the two is how they trigger the electric jolt to the SCA victim. With manual defibrillators, the responder must press the shock button when the AED instructs them to do so. The defibrillator delivers the shock when the button is pressed.

How many volts does the machine use?

Energy Level

The energy of an automatic defibrillator is measured in joules. A joule is the amount of work done by one amp of current passed through an ohm for one second.

When we express it in a formula, it is generally stated as follows:

Joules (Energy) = Voltage X Current X Time

In modern defibrillator parlance, joules have taken the place of current as a form of measurement.


The current that defibrillates the heart is measured in volts. Voltages/Impedances (resistance) is used to express current as a voltage divided by impedance.


There is resistance to current flow within the circuit and in a patient’s body. The quantity of impedance a patient exhibits cannot be precisely assessed. Before giving defibrillation shocks to the defibrillator paddles or pads, it’s difficult to accurately assess certain bodily measurements such as weight, temperature, and slipperiness. Ohms are the unit of impedance measurement.


An AED is a device that can administer an electric shock to the heart in order to restart it. The stronger the electrical shock, the more joules are needed.

The wattage or volt indicates the intensity of the muscular current that passes through the chest wall and into muscle cells. Voltage (V) is one of the most common types. A joule (J) is a measurement of energy or work, defined as the amount of energy transferred (or work done) when applying a force of one newton through a distance of one meter.

Both joules and volts are utilized in an AED machine to measure electricity.

Modern AEDs typically deliver between 200 and 1000 volts to the heart. The SA node is reset by such a strong current and directed back to its normal duty of delivering current.

An external defibrillator usually uses as much energy as it takes to light a 100-watt bulb for a few seconds. This energy is about 300 joules which is much higher than what the human body is used to. These biphasic defibrillation devices can easily run in regular electrical activity with moderately high voltage. Therefore it has proved helpful in emergency medical services to defibrillate heart muscle.

Note that there are 6 primary FDA-approved AED manufacturers for public access AEDs in the US. Cardiac Science, Philips, Defibtech, Physio-Control, Zoll, and Heartsine. Each brand and model has different approaches to escalating joules.

Portable Automated Defibrillators

Portable defibrillators are also available, which can be useful in emergency situations and can easily be carried if you look closely at the walls of airports lobbies, schools, and other public places. Now, portable AEDs are frequently used at home, in vehicles, and at work. These are medical services providers’ portable upgrades of biphasic defibrillators.

Portable Automated Defibrillators

Modern AEDs are light and very portable. The technological advancements in AEDs have resulted in lightweight devices that are still very effective.

AEDs are designed to work with the right energy levels for defibrillation. The electrical shock should be applied through electrodes on the chest wall which ensures that the current flows through the heart. Adequate energy is necessary to induce fibrillation of SA node, which will result in inducing a normal heartbeat.

Risk factor of Defibrillation:

Bystanders typically are hesitant to try and help an SCA victim due to a lack of knowledge and often a fear that they might do more harm to the victim. Modern AEDs are so advanced they will not deliver a shock if the victim is not suffering from a shockable rhythm. The AED will monitor the ECG of the patient and determine if a shock should be applied or not. Note that many times the AED will recognize that there is no shockable rhythm and will not apply a shock.

Risk factor of Defibrillation:

Injuries from portable AEDs are quite rare if you use them properly. Portable AEDs include various accessories such as self-adhesive electrodes, that minimize the risk factors of AED use.

American Heart Association also claims that early defibrillation of a sudden cardiac arrest victim right after his collapsing proved to be life-saving. It revives the normal electrical activity of the heart and makes a difference in life and death.

Like every other piece of equipment or machinery, portable AEDs also require maintenance to ensure the device will be ready for service when needed. Each state in the US has its own AED laws requiring different requirements. The following are standard high priority items with managing an AED program:

  • track electrode pads expiration dates
  • track battery expiration dates
  • perform and record monthly readiness checks for each AED

At AEDUSA we provide our customers free access to our AEDMD management program to track all expiration dates and to perform monthly readiness checks. We work hard to meet the high standards and requirements for all AED programs in the US.

What are the advantages of AEDs?

Modern AEDs are so advanced they almost operate on autopilot. A human still needs to perform CPR by applying compressions to the victim’s chest to force blood to continue to pump throughout the body. Some additional features of AEDs are:

  • simple design
  • very automated treatment of sudden cardiac arrest with little or no training
  • audio and sometimes visual prompts

The life-saving connection from the AED to the SCA victim is through the electrode pads that are placed on the patient’s chest. Modern electrode pads have an adhesive gel that helps stick the pads to the body of the SCA victim. The AED when applied to the SCA victim automatically detects the patient’s heart rhythm through an ECG and determines if the patient has a shockable rhythm. If a shockable rhythm is detected then the AED will deliver a shock through the electrode pads to the patient’s chest.

What are the advantages of AEDs?

AEDs are stored in stand-by mode meaning the AED is on and waiting for service. When activated an audio prompt instructs the user with audible directions to follow. If the AED detects an arrhythmia then the AED will instruct the user to perform CPR immediately. If no shock is advised then compression should be performed by the user.

It’s essential to keep pushing chest compressions by administering CPR to keep some blood flowing through the body. Another advantage of using an AED is that it is self-explanatory. Any person can use it even if he has no medical training.

Why do we need a portable AED in emergency medical services?

Cardiac Arrest:

CPR may be a life-saving technique if performed immediately after cardiac arrest, but it is not enough on its own. A responder should try to defibrillate immediately. When a person suffers cardiac arrest, the heart does not pump blood on its own. Instead, it must be pumped manually by CPR. The SA node must be reset with electric shock in order to restore the heart’s normal rhythm, making it difficult at times. It should be mentioned that CPR on its own will not reestablish a normal heart rhythm; rather, the node’s electrical current is also required. It aids in combatting ventricular fibrillation.

Mouth to mouth resuscitation:

Mouth-to-mouth resuscitation is not utilized to the extent it was in the past. The purpose of rescue breathes is to fill the lungs of a cardiac patient with your oxygen, which forces the patent’s lungs to re-oxidize the blood.

You may be aware, however, that the majority of the air we breathe out is carbon dioxide. Thus, the air through rescue breathes does not enrich the blood of the patient. Another drawback of mouth-to-mouth resuscitation is that the rescue breathes may pass through the esophagus and stomach. Air in the stomach may cause cardiac arrest patients to vomit.

The problem in this scenario is electrical, so manually pumping or applying rescue breathing will simply extend the life of cardiac arrest patients. However, until the electric movement in the heart is restored, the issue will not be entirely resolved.

Cardiopulmonary Resuscitation:

Hands-only CPR can be beneficial for recovering sudden cardiac arrest patients. The responder must deliver CPR and electric shock treatment until the patient’s natural rhythm is restored in such a scenario. An SCA event is a high-stress medical emergency but quick action with bystanders and an AED can dramatically improve the survival chances of the victim.

How vital is the 360 joules defibrillator?

Some SCA patients may require more than 200 joules of heart fibrillation. Clinical data suggests the union of higher biphasic shock energy with high compression rates. That’s why we offer a wide range of defibrillators up to 360 joules.

How vital is the 360 joules defibrillator?

We use biphasic truncated exponential in our defibrillators and generate the most commercially available manual and external defibrillators in the US. Researches prove that CPR patients can be easily be saved by 360 joules defibrillators or biphasic defibrillation. However, low-energy defibrillators use rectilinear biphasic waveforms, which are not as effective as 360 J defibrillators.

How can defibrillation help an SCA (sudden cardiac arrest) victim?

Immediate CPR is critical during SCA. The use of a defibrillator in the first three minutes after collapse increases the chance of survival exponentially.

How can defibrillation help an SCA (sudden cardiac arrest) victim?

The automated Defibrillator will typically evaluate the heart rate through the patient’s chest and advise the responder if a shock should be administered. AEDs provide relatively high voltage shock to the patient’s heart receiving between 100 to 360 joules of electrical energy; it depends upon the brand of AED being used. Successful defibrillation pauses the electrical activity in the heart of the cardiac arrest victim. This short pause from ventricular fibrillation is often enough to bring back the average patient’s heart rhythm.

Things to remember while using AEDs

AED is an easy subject to grasp, regardless of whether you have any AED training or are completely new to the idea. If you find yourself in a position where it’s time to deploy an AED on someone, keep these points in mind:

Call 911 first:

Before doing anything to the patient:

  1. Call for emergency medical help.
  2. If the situation worsens and the patient’s heart rhythm appears to be fading, attempt chest compressions as soon as possible.
  3. Call 911 and put the phone on speaker to let the responder hear the patient’s condition when you do CPR.

He will guide you further if you need public external defibrillators or not. Perform compressions constantly until the patient regains the standard heart rate.

Stay Calm:

Panic will only worsen the situation. Stay calm and consider carefully what you should do next. When you happen to see a person in what you suspect is an SCA event, act decisively and quickly with the following:

  • is the patient breathing?
  • Can you feel the patient’s pulse?
  • Is anything blocking the airway?

Your priority should be to overcome your fear and panic. Take deep breaths, if possible, or do a fast breathing exercise for a few seconds if needed.

Move Quickly:

After you have overcome your anxiety and panic, quickly decide your next step. Check the pulse rate of the victim. If the pulse seems normal then take him to the hospital urgently. Otherwise, if the pulse rate seems to fade, call 911. Apply CPRs if necessary. But remember that your next step must be according to the victim’s condition.

It would help if you decided what step you should take next. If you perform successful defibrillation right after five minutes of the patient’s collapsing, then the chance of survival is 50-70%. This ratio decreases by 10% as each minute passes.

Turn on the device:

AEDs should be stored in Standby mode meaning they are turned on and ready for service. Verbal instructions and audio cues may help people who are unfamiliar with AEDs. Make the most of the automated instructions in such cases.

Hands off during electric shocks:

Avoid contact with the SCA victim when the AED is delivering a shock. All modern AEDs will warn the responder to stand back and not touch the victim. Audible commands will instruct the responder when they should resume CPR if needed. Note that it is very common for multiple shocks to be administered in order to save an SCA victim.

Hands off during electric shocks:

Get others involved:

If you see some other person nearby, ask them to help you. Take turns in doing CPRs so that you do not become exhausted by doing it alone. Or you can also ask the other person to call 911.

In moments of crisis, it is always the best option to get others’ help. Even if others may not be a great help, but they can at least provide emotional support which is crucial in such situations.

Be Prepared:

Be prepared for any emergency. If you have a history of cardiac disease make sure your home and office are set up to manage any emergency. Keep track of the nearest AEDs and individuals with CPR skills.


All in all, this is just a brief introduction to AEDs. Arrhythmia and fibrillation are two distinct but equally serious heart rhythm disorders. Arrhythmia and fibrillation are both fatal if not treated promptly. The first thing you should remember in these cases is to keep calm and not to panic.

The most amazing aspect is that technology has revolutionized the way we live. We may now handle terrifying events, arrhythmia, and fibrillation with top technologies like AEDs.

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