In this article, we’ll explain what an Automated External Defibrillator (AED) is, how it works, and how to use one alongside cardiopulmonary resuscitation (CPR) to give casualties the best chances of survival and recovery.
What is an AED?
AED stands for ‘Automated External Defibrillator’. It is a portable, life-saving device that is used to restore normal heart rhythm in the event of a cardiac arrest. AEDs are designed to be used by laymen and simple, easy-to-follow voice prompts guide the user through the necessary steps. An AED shouldn’t be used alone; to improve a casualty’s chances of survival and recovery it is vital that an AED is used in conjunction with cardiopulmonary resuscitation (CPR).
How does an AED work?
An AED works by analysing a casualty’s heart rhythm and, if necessary, delivering an electrical shock to correct dangerous arrhythmias. This is known as defibrillation.
Here’s a simple breakdown of how an AED works:
Heart Rhythm Analysis
When applied to a casualty’s chest, sensors in the AED’s adhesive pads, or electrodes, analyse the heart’s electrical activity. If the AED detects life-threatening arrhythmias – such as ventricular tachycardia (VT) or ventricular fibrillation (VF) – it alerts the user that an electrical shock is advised.
Shock Advised
An AED will only advise a shock if a shockable heart rhythm is detected. Shockable rhythms like ventricular tachycardia (VT) or ventricular fibrillation (VF) are life-threatening as they prevent the heart from pumping blood effectively.
No Shock Advised
If the casualty’s heart has no heartbeat or detectable electrical activity (called asystole), the AED will not advise a shock, as this condition cannot be corrected by defibrillation. If the casualty’s heart rhythm is normal, the AED will also not advise a shock, as one is not needed.
Controlled Electrical Shock
AEDs deliver a controlled electrical shock via the two electrodes, or pads, placed on the casualty’s chest. The electrical shock interrupts the abnormal heart rhythm, which (hopefully) allows the heart to ‘reset’ itself to a normal, healthy rhythm.
Can you restart someone’s heart without an AED?
No, it is not possible to restart a stopped heart by administering CPR alone. CPR is a critical, life-sustaining treatment that maintains the oxygen supply to the body’s vital organs (such as the brain) by manually circulating blood throughout the body. CPR should be administered until an AED is available to deliver an electrical shock capable of restoring the heart’s normal rhythm.
Do you start CPR or AED first?
It is important to start CPR before using an AED. If a casualty is not breathing and has no pulse, ask someone else to call the emergency services and fetch an AED, while you begin CPR immediately. CPR must be started as soon as possible (ideally within four minutes) to avoid potential brain damage due to lack of oxygen.
How to do CPR
Use the acronym DRABCD to remember the steps for starting and administering CPR:
Danger: Ensure that it is safe for you to approach the casualty
Response: Ask the casualty, “Hello, can you hear me, are you alright?”
Airway: Open the casualty’s airway using ‘head-tilt/chin-lift’ method
Breathing: Look, listen, and feel for breathing for 10 seconds
Call & Circulation: Call the emergency medical services and start chest compressions
Defibrillation: Find and use an AED together with CPR
How to do CPR chest compressions
To perform CPR chest compressions, follow these steps:
- Place the casualty on a hard, flat surface, preferably not a bed.
- Place the palms of your hands on top of each other in the centre of the chest.
- Interlock your elbows so that you are positioned directly above the casualty’s chest.
- Push down hard on the chest to a depth of approximately 5-6cm. Do not be afraid to push hard; you must push hard enough to compress the heart between the sternum and the spine.
- Release the compression and allow the chest to recoil back completely, but do not move your hands away from your location on the chest as you need to continue performing compressions quickly, at a rate of 100-120 compressions per minute. Press hard and fast, you need to do almost two compressions per second!
- Perform 30 chest compressions, followed by two rescue breaths.
- Repeat this cycle until an AED becomes available or paramedics arrive.
How to give CPR rescue breaths
To perform CPR rescue breaths (also called mouth-to-mouth breathing or ventilation), follow these steps:
- Start CPR by performing 30 chest compressions.
- Ensure that the casualty’s airway is open by using the ‘head-tilt/chin-lift’ method.
- Place a one-way valve face shield in place between the casualty’s teeth or place a pocket mask over the casualty’s nose and mouth.
- Using the hand that is tilting the forehead backwards, pinch the casualty’s nostrils closed.
- Place your mouth over the casualty’s mouth, forming a seal so that air cannot escape.
- Deliver one short breath by blowing exhaled air for one second into the casualty’s mouth, airway, and lungs.
- If the casualty’s chest rises, sufficient air has been delivered. Do not blow too much, as air may enter the casualty ’s stomach and cause complications.
- Administer another rescue breath (two in total).
Repeat the cycle of 30 chest compressions followed by two rescue breaths until an AED becomes available or paramedics arrive.
How to use an AED
In the event of a cardiac arrest, an AED should be used as soon as possible, at least within the first 10 minutes of starting CPR. AEDs are very easy to use. Stickers and audio voice prompts guide the user through the defibrillation steps.
- Continue with CPR until the AED arrives.
- Ideally, one person continues CPR while the other operates the AED.
- Apply the AED pads as directed on the packaging and plug the pads’ cord into the AED machine.
- The AED will tell you to stand clear while it analyses the heart rhythm.
- If the AED detects a shockable heart rhythm, it will begin to charge.
- Once the AED is charged, it will prompt the user: ‘Shock advised, stand clear, do not touch the casualty’.
- Say, “Stand clear,” and double-check that no one is physically touching the casualty.
- Push the shock or orange button and the shock will be delivered.
- Immediately continue with CPR.
- Leave the adhesive pads attached to the casualty’s chest. The AED will reanalyse the casualty’s heart rhythm every few minutes and continue to advise the user whether a shock is advised.
- Continue CPR until paramedics arrive, or the casualty regains consciousness.
Get hands-on CPR practice in first aid training
The only way to ensure that you’re able and ready to help in a real medical emergency is to get hands-on, practical first aid training. First Aid, Fire and Safety Training offers the following first aid courses:
- First Aid NQF Level 1: two-day course
- First Aid Levels 1, 2 & 3: five-day course
- CPR for Everyone: three-hour course
- CPR for Professionals: four-hour course
- BLS for Healthcare Providers: five-hour course
Contact us to find out more or to book your spot.
