AEDs – The only effective intervention for sudden cardiac arrest
An automated external defibrillator (AED) is a small, lightweight, and portable electronic device that delivers an electric shock through the chest wall of a person whose heart has stopped beating. It is proven to be one of the most important tools in saving the life of someone suffering sudden cardiac arrest; that's why St. John Ambulance recommends that you equip your space with an AED.
What is sudden cardiac arrest? It occurs when heart function ceases abruptly and without warning. The heart is no longer able to pump blood to the rest of the body. Not to be confused with a heart attack, sudden cardiac arrest is an electrical problem that creates an abnormal heart rhythm, preventing the heart from pumping blood to all vital organs.
Sudden cardiac arrest is unpredictable; it can happen anywhere, anytime, at any age, and without any warning. In fact, one occurs every 12 minutes in Canada and, with each passing minute before AED application, the probability of survival declines by 7-10%. Time is of the essence in these situations and using an AED is the only effective intervention.

How does an AED work?
An AED is programmed to recognize and shock two types of abnormal heart rhythms: Ventricular Fibrillation (VF) and Pulseless Ventricular Tachycardia (Pulseless VT). Because of this, it will not shock a normally beating heart.

If an AED recognizes either of these rhythms, it will charge and indicate that a shock is advised, usually with a voice command. The benefit of the shock is to correct the abnormal electrical disturbance that is causing the irregular heart rhythm, and re-establish a normal heart rhythm.
Be aware that legislation in most provinces and territories across Canada protects individuals who use AEDs from liability when they are used in the context of saving a life, so don’t be afraid to intervene! The only provinces and territory without Good Samaritan laws are New Brunswick and Nunavut.

Using an AED - A step-by-step guide
Because all AEDs emit clear voice prompts and most have legible and visual instructions, they can be used by anyone, regardless of age of experience. In fact, using an AED is one of the easiest first aid techniques you can master.
Once you press the ON button or open the cover on an AED, it will guide you through the following step-by-step process with clear voice prompts:
- Call 9-1-1
- Expose the chest.
- Attach cables to electrode pads (with some models, both are pre-connected).
- Make sure the chest is dry – the pads will adhere better to a smooth, dry surface. If the chest is very hairy and you have access to the necessary materials, shave the chest.
- Peel away the protective plastic and attach the electrode pads. Position a pad on the right upper anterior side of the person’s chest, just below the collarbone. Position the second pad on the left lower anterior chest wall, just below the nipple. Some electrodes have handy diagrams on them, showing you where they should be placed.
- Stand back and ensure no one is touching the individual.
- Press the ANALYZE button on the defibrillator and follow the voice prompts (some machines automatically analyze when the pads are applied).
- Once the machine has analyzed the heart rhythm, it will indicate via voice control whether a shock is required, or no shock is required.
- If shock is required, push the flashing shock button. Some AEDs will automatically shock the casualty without the need to push a button.
While using an AED is simple, we recommend pairing it with CPR and AED training. The other benefit of a St. John Ambulance training program is that we can guide you through some of the considerations and special circumstances for using an AED, so tha you are SETTM to Save a Life.
Post-AED-Use Patient Care
If an incident requires the use of an AED, ensure whoever used it remains on scene to give first responders a complete report of the event and any significant findings. Afterwards, have that person write an account of:
- What happened,
- What steps were taken, and
- What symptoms were witnessed
This documentation is part of the patient's private medical history, and must be treated as confidential at all times. However, it's an important step, as it may contain information that will be helpful to the patient's subsequent treatment and recovery.
Also, be aware that there may be more than one patient in the aftermath of an incident. Events requiring the use of a defibrillator can be traumatic, especially for people with no first-responder training. Be sure your staff, any participants, and witnesses are provided with a debriefing, and, if required, refer them to professional counselling services within 24 hours of the incident. Most fire halls and police stations can provide direction in securing debriefing services. However, you should prepare a contact name and number in advance.
How AEDs have saved lives
Having the confidence to respond to a cardiac arrest with an AED can mean the difference between life and death. Reports of AED success stories regularly appear in the media – here are just some examples of how AEDs can save lives.
As AEDs have become more portable, user-friendly, and compact, they have also become more economically accessible to the average consumer. With the evolution of the technology, the only real question that remains is how anyone can afford not to have an AED handy.
Want to learn how to use an AED with confidence?
St. John Ambulance provides a range of AED training programs. If you’re interested in knowing more about how to use an AED and couple it with CPR, you can find a program near you. With nearly 100 locations across Canada, as well as some courses found online, St. John Ambulance can help equip you with the training and tools to save a life.
Where can I take St. John Ambulance first aid training to learn how to use an AED? We are the largest provider of regularly scheduled first aid training programs in Canada. Please visit the Registration page to find first aid training offered in your province. |
How do I register for St. John Ambulance first aid training, including skills for proper use of an AED? We offer training right across Canada, as well as online (selected courses only). Please visit the Registration page to register for a first aid training session that’s convenient for you, or call your local office. Click here for our locations. |
How can I speak to someone at St. John Ambulance if I have questions or want to find out more? Please call your local office. Click here for our locations. |
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