How to use an AED

If someone collapses and is unresponsive with abnormal or no breathing, treat it as possible sudden cardiac arrest. Call 995, start CPR if you are able, and get an AED on the scene. The device will tell you what to do next. You do not need to memorise every brand’s interface.

This page is educational, not a certification course. Practise on a course when you can. In a live emergency, prefer myResponder for official mapping and volunteer support.

Before you touch the AED

Confirm the person is unresponsive and not breathing normally. Agonal gasps (slow, irregular, snoring-like breaths) still count as abnormal breathing in this context.

Call 995 yourself, or assign one person by name or clothing colour to call and stay on the line. Put the phone on speaker if you are alone so you can follow dispatcher instructions while you work.

Send a second person for the nearest AED. Point them at a landmark if you know one: “Security desk on level 1,” “Customer service outside Uniqlo,” “Fire command room.” If you are alone, use the phone on speaker, start CPR as directed, and fetch the AED only if you can return within moments. Do not wander the building while the person lies alone for long.

Step-by-step: using a public AED

Follow the six steps below in order. Exact button labels vary by brand. Voice prompts override any guesswork.

1. Call 995 and start CPR if trained

Call 995 (or have someone else call) when the person is unresponsive with abnormal or no breathing. Start chest compressions if you are trained, or as the dispatcher coaches you.

Push hard and fast in the centre of the chest. Minimise interruptions. If you are not trained, the dispatcher can talk you through hands-only CPR. Do not delay the call while you look for a device.

2. Send someone for the nearest AED

Send someone for the nearest AED while CPR continues. Search AEDLocator in advance for places you frequent so you already know likely spots. In an emergency, prefer myResponder for the freshest official map rather than opening a web directory under stress.

Bring the entire kit to the casualty. Open wall cabinets fully; pads and scissors often sit in a pouch with the unit.

3. Power on the AED

Place the AED beside the person. Power it on. Some units start when you open the lid. Listen to the voice prompts and glance at the screen diagrams if present.

Expose the bare chest. Cut or tear clothing as needed. Dry the skin if wet. Shave pad sites briefly if dense hair prevents adhesion and a razor is in the kit.

4. Attach the pads

Peel the pads and stick them exactly as shown on the pad diagrams (usually one below the right collarbone, one on the left lower chest/side). Press firmly from the centre outward so air bubbles leave.

Do not place pads over medication patches, implanted device bumps, or dense jewellery at the site. Move patches aside if needed and wipe residue. Keep pads away from water, metal surfaces connecting to other people, and overlapping each other.

If paediatric pads or a child key/mode exist and the casualty is a child, use them as labelled. Otherwise follow the unit’s prompts for adult pads.

5. Stand clear

When the AED says it is analysing, stop CPR and ensure nobody is touching the person. Say “Clear” out loud and look at head, hands, and legs.

If a shock is advised, the unit will charge. Stand clear again, then press the shock button if the device asks you to. Fully automatic models may shock on their own after a warning. Immediately resume compressions when prompted.

If no shock is advised, restart CPR when the AED tells you to. Leave the pads on. The device will re-analyse after cycles of CPR.

6. Continue CPR as directed

Keep going until SCDF or other professionals take over, the person shows clear signs of life (purposeful movement, normal breathing), or you are too exhausted and a trained replacement steps in.

Do not remove pads to “check” between cycles unless the device or professionals instruct you to. Report what you did when responders arrive: time of collapse if known, shocks delivered, and any changes you saw.

What the AED will not do

An AED will not shock a person who does not need it based on its analysis. It will not replace high-quality CPR. It will not treat every cause of collapse (fainting, seizure, stroke, low blood sugar look different). When the picture is unclear, stay on the line with 995.

Do not delay calling emergency services to hunt for a device across multiple floors. Call first, assign roles, then fetch.

Practical tips that trip people up

Wet or sweaty skin. Dry thoroughly or pads will peel during compressions.

Hairy chest. A quick shave of pad sites beats failed analysis from poor contact.

Implanted pacemaker or ICD. Place pads at least a few centimetres away from the visible bulge, still roughly following the standard positions.

Metal jewellery. Remove items that sit under a pad site. You do not need to remove every necklace if it is clear of both pads.

Moving vehicles or escalators. Get the person onto a stable, dry surface when you can do so safely before analysing.

Multiple helpers. One person compresses, one manages the AED and clear checks, one meets the ambulance at the entrance with floor and lift instructions.

After the event

Leave the AED and packaging for responders or building staff so used pads can be replaced and the unit checked. Note the location ID or building name if you can. If you used a device listed on AEDLocator, the building operator still owns maintenance; our directory only mirrors SCDF open data.

Consider a formal CPR/AED course afterward. Muscle memory is easier to build when nobody’s life is on the line.

Related guides

• Cardiac arrest vs heart attack: symptoms and which pathway needs an AED
• What is an AED?: what the device does and who can use it
• What to do before an ambulance arrives: scene safety and role assignment
• Where AEDs are commonly found: where to look in Singapore buildings
• Opening hours and access: why a listed AED may still be locked

FAQ: using an AED

Can I hurt someone by using an AED incorrectly?

If you follow the voice prompts, stand clear during analysis and shock, and keep pads on bare dry skin as shown, the device is designed for bystander use. The bigger risk in cardiac arrest is doing nothing. Still call 995 so professionals are on the way.

Should I practise on a real public AED?

No. Do not open sealed public kits for practice. Use training units at a course or community event. Public AEDs need intact pads and batteries for real emergencies.

What if I don’t know where the nearest AED is?

Ask building security, customer service, or a staff member immediately. Many wear radios and know the cabinet location. For places you visit often, look them up on AEDLocator ahead of time and note the floor description on the listing.

Do I stop CPR while the AED is charging?

Stop contact when the device says it is analysing or about to shock. Between those moments, resume compressions as prompted. Minimising hands-off time matters.