How to Use an AED in a Cardiac Emergency

A person who has collapsed, is unresponsive and is not breathing normally needs immediate action. Knowing how to use an AED can turn the first few minutes of a cardiac arrest from confusion into a structured, life-preserving response. An automated external defibrillator is designed to be used by trained and untrained bystanders alike: it gives clear voice and visual prompts, assesses the heart rhythm and only advises a shock when one is needed.

The objective is straightforward: call for help, start CPR, bring the AED quickly and follow its instructions without unnecessary delay. In a workplace, school, public venue or family setting, a confident response protects the casualty’s best chance of survival until emergency medical teams take over.

Recognise cardiac arrest and act immediately

Cardiac arrest is not the same as a heart attack, although a heart attack can lead to one. In cardiac arrest, the heart stops pumping blood effectively. The casualty will usually be unconscious, unresponsive and either not breathing or only making irregular gasping sounds. These occasional gasps, known as agonal breathing, are not normal breathing.

Check that the area is safe before approaching. Speak loudly, tap the casualty’s shoulders and ask whether they can hear you. If there is no response, open the airway by gently tilting the head back and lifting the chin, then check for normal breathing for no more than 10 seconds.

If they are not breathing normally, ask someone to call the local emergency number and send another person to collect the nearest AED. In the UAE, ambulance services can be reached on 998. If you are alone, call emergency services on speakerphone so you can begin treatment immediately. Do not leave an adult casualty to search for an AED if no one else is available unless it is clearly within immediate reach.

Start chest compressions as soon as possible. Place the heel of one hand in the centre of the chest, place the other hand on top and interlock your fingers. Press down firmly and quickly, aiming for a rate of 100 to 120 compressions per minute and a depth of around 5 to 6 cm for an adult. Allow the chest to rise fully after every compression. If trained and willing, give two rescue breaths after every 30 compressions. If you cannot give breaths, continuous chest compressions are far better than doing nothing.

How to use an AED safely

As soon as the AED arrives, switch it on. Most units have a prominent power button or activate when the lid is opened. Put it beside the casualty’s head, where its instructions can be heard clearly and the rescuer can work without obstructing CPR.

Expose the chest and make sure it is reasonably dry. If the casualty is wet from rain, a pool or sweat, quickly dry the chest before applying the pads. There is no need to move them from a wet surface unless they are lying in standing water or there is another immediate danger. Remove any medication patches from the intended pad area, wiping away residue if possible. If there is significant chest hair that prevents the pads from sticking, use the razor often supplied in the AED kit to clear only the pad locations.

Open the pad packet and apply the adhesive pads exactly as shown in the diagrams. For most adults, place one pad high on the right side of the chest, just below the collarbone. Place the second pad on the left side of the chest, below the armpit. Press each pad firmly onto bare skin so it makes full contact.

Some AEDs have pads already connected; others require the plug to be inserted into the machine. Follow the unit’s prompt. Keep chest-compression interruptions as short as possible while the pads are applied.

Once the pads are in place, the AED will tell you to stop CPR while it analyses the heart rhythm. Make certain nobody is touching the casualty. State clearly, “Stand clear,” and visually check that hands, clothing and equipment are away from them. Movement can interfere with analysis.

If the AED advises a shock, it will charge automatically or ask you to press a flashing shock button. Again, ensure everyone is clear before delivering the shock. Do not touch the casualty while the shock is given. Oxygen equipment, if in use, should be moved away from the chest area during analysis and shock delivery. The AED will then instruct you to restart CPR immediately, usually for around two minutes before it reassesses the rhythm.

If the AED states that no shock is advised, begin or resume CPR at once. A no-shock message does not mean the casualty is safe or that you should wait. They still need continuous care and emergency medical support.

Use the AED with minimal interruptions

The AED is not a replacement for CPR. It works alongside it. High-quality chest compressions keep blood moving to the brain and heart muscle while the AED identifies a rhythm that may respond to defibrillation.

This is why teamwork matters in workplaces and public settings. One person can continue compressions while another prepares the AED. When the machine asks for analysis, stop briefly. As soon as it permits, return to compressions. Avoid pausing to discuss the situation, rearrange equipment or wait for a manager’s approval. The casualty’s condition determines the urgency.

Continue the cycle of CPR and AED prompts until one of three things happens: the casualty begins to show clear signs of life and breathes normally, emergency responders take over, or you become physically unable to continue. If the casualty starts breathing normally but remains unconscious, leave the pads in place, place them in the recovery position if safe to do so and monitor their breathing closely. The AED may be needed again.

Practical considerations that should not delay treatment

AEDs are designed with safety controls. They analyse the casualty’s heart rhythm and will not recommend a shock unless the rhythm is suitable. The most common risk is not misuse of the machine - it is delay in starting CPR and applying the pads.

A few circumstances require practical adjustments. If the casualty has a visible pacemaker or implanted defibrillator, often identifiable as a small raised area beneath the skin near the upper chest, place the AED pad at least a few centimetres away from it. Do not place a pad directly over jewellery, though a necklace need not be removed if it does not interfere with pad placement.

For children, use paediatric pads or an AED child setting where available, generally for children aged one to eight years. Follow the pad diagrams carefully. If paediatric pads are unavailable, use standard adult pads rather than delaying defibrillation. For an infant under one year, use an AED only if an appropriate device and pads are available and in line with local clinical guidance.

Do not use an AED on a casualty who is conscious and breathing normally. If there is any doubt, assess responsiveness and breathing, call emergency services and follow their instructions. Equally, do not remove the pads or switch off the AED simply because it has not advised a shock. Keep following the prompts until professional help arrives.

Readiness is a workplace responsibility

An AED is most effective when it is accessible, visible and supported by trained people. Organisations should know where their units are located, keep access routes clear and nominate responsible staff to check battery status, pad expiry dates and any fault indicators. A locked cabinet may protect equipment, but it can also cost critical time unless access arrangements are clear to all staff, visitors and security personnel.

Training remains the best way to replace hesitation with disciplined action. A practical first aid course allows teams to practise chest compressions, pad placement, communication and handovers under realistic pressure. It also helps organisations build emergency response plans that suit their premises, staffing patterns and risk profile. Lifesaver Abu Dhabi supports organisations and communities with practical, accredited training built around these real operational needs.

The best moment to learn where the nearest AED is located is before someone collapses. Identify it, understand who calls for help, and ensure the people around you know that early CPR and decisive AED use can give a stranger, colleague, pupil or family member the time they need to survive.