How to use a defibrillator (AED) in an emergency: the guide to saving lives

Every year in Switzerland, thousands of lives could be saved if first aid techniques were better known. In the event of cardiac arrest, the reaction of a bystander – whether trained or not – can make the difference between life and death. Yet many people hesitate to intervene for fear of doing the wrong thing.

Using an automatic external defibrillator (AED) is simple, guided and within everyone’s reach. But you still need to know how to recognise an emergency, act quickly and follow the right steps.

In this article, you’ll discover how to use an AED effectively in a critical situation, what good reflexes to adopt and why it’s essential to train in cardiopulmonary resuscitation with a programme like the BLS AED SRC. Whether you’re an individual concerned about protecting your loved ones or a professional looking for safety in the workplace, this guide will help you become a actor in the chain of survival.

1. What is a defibrillator (AED) and when should it be used?

The automatic external defibrillator – more commonly known as an AED or AED – is a portable medical device designed to restore normal heart rhythm in the event of sudden cardiac arrest. It automatically analyses the heart’s rhythm and, if necessary, delivers an electric shock (defibrillation) to restart cardiac activity.

These systems are now widely available in French-speaking Switzerland, at stations, businesses, sports centres, schools, etc. They are now widely available, but their effectiveness depends above all on how quickly the witness can intervene.

The AED is only used in very specific situations:

• The person is unconscious.
• She does not breathe normally (gasping or lack of breathing)
• It does not react to stimulation.

That’s when every second counts. The device guides the user by voice, step by step. Even without prior training, it is possible to take action. However, with BLS AED SRC-certified training, you’ll be more efficient, more cool-headed, and able to intervene with confidence from the very first seconds.

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2. Recognising cardiac arrest: the tell-tale signs

Identifying a life-threatening emergency quickly is crucial if the chain of survival is to be set in motion without delay. Sudden cardiac arrest cannot be prevented: it occurs suddenly and requires immediate action.

The characteristic signs of cardiac arrest

Cardiac arrest should be suspected if the person :

• Losing consciousness suddenly
• Does not react to any stimulus (speech, shaking, pain)
• Does not breathe or has abnormal breathing (gasping, panting)

Do not try to feel the pulse: this step is reserved for professionals. The absence of a response and normal breathing is enough to suspect cardiorespiratory arrest.

What should I do immediately?

• Call 144: this is the emergency number in Switzerland.
• Begin cardiopulmonary resuscitation (CPR): 30 deep chest compressions followed by 2 breaths (if trained), or continuous cardiac massage otherwise.
• Request an AED: if a defibrillator is available, have it brought in and switch it on as soon as you receive it.

Every minute without massage or defibrillator shock reduces the chances of survival by 7 to 10%. Acting quickly means giving the victim a real chance.

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3. Detailed steps: how to use an AED

Using a defibrillator (AED) is designed to be intuitive. Thanks to its voice and visual instructions, anyone can use it effectively, even without prior training. Nevertheless, knowing the steps in advance boosts confidence and reduces stress.

Switch on the appliance immediately

As soon as you receive the AED, switch it on by pressing the button provided or simply by opening the cover, depending on the model. The device will guide you verbally through the rest of the procedure.

Undressing and preparing the victim

Strip your upper body to expose your breasts. If it is damp (rain, perspiration), dry it quickly. If necessary, shave any thick hair with the kit supplied to ensure good adhesion of the electrodes.

Place the electrodes correctly

Attach the two electrodes according to the diagrams shown:

• The first under the right collarbone
• The second on the left flank, under the armpit

Make sure they adhere well to the skin.

Launch the analysis and deliver the shock

Once the electrodes are in place, the AED will analyse the heart rhythm. Do not touch the victim during this phase. If a shock is recommended, press the button when prompted. Then resume chest compressions immediately.

Continue to perform these actions until help arrives

Continue resuscitation (CPR) following the voice prompts from the AED. Alternate compressions and defibrillations if necessary, until the victim shows signs of recovery or until the emergency services take over.

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Key steps for using a defibrillator (AED) in an emergency situation

1. Turn on the AED as soon as you receive it
   Press the button or open the cover to activate the device. It will immediately start guiding you.
2. Expose the victim’s chest
   Remove any clothing and make sure the skin is dry. Use the razor provided if necessary.
3. Place the adhesive electrodes
   Position them according to the diagram: one under the right collarbone, the other on the left flank.
4. Let the device analyse the heart rhythm
   Do not touch the victim. The AED automatically determines whether a shock is required.
5. Press the shock button if recommended
   Make sure no-one is touching the casualty, then deliver the shock as instructed.
6. Restart chest compressions immediately
   Continue CPR until help arrives or the victim shows signs of recovery.

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4. What to do after using an AED?

Once the AED has been used and help is on its way or already present, certain steps are essential to ensure complete care for both the victim and the responder.

Inform emergency services on arrival

As soon as the professionals arrive, give them the following information:

• The number of shocks delivered by the AED
• Approximate duration of resuscitation
• The victim’s reactions during the operation

This data enables emergency physicians to adjust their protocol according to what has been done in the field.

Caring for the appliance after use

An AED that has been used must be checked quickly:

• Used electrodes must be replaced
• Check the condition of the battery
• The appliance must be returned to working order for future use.

In companies, this check is often carried out by the person responsible for safety or medical equipment.

Thinking about psychological support

Responding to a cardiac arrest can be emotionally distressing, even if the procedure has been followed correctly. It’s a good idea to talk things through with colleagues, a first aid trainer, or to consult a professional if the need arises. Some BLS AED courses include modules on managing post-intervention stress.

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5. Why BLS AED SRC training is essential

Knowing how to use an AED in a real-life situation cannot be improvised. Even if the device is designed to guide the user by voice, only certified training will enable you to gain speed, precision and composure.

Structured, supervised learning

The BLS AED SRC (Basic Life Support – Automated External Defibrillator) training course, accredited by the Swiss Resuscitation Council, teaches:

• Recognising vital signs
• Performing cardiac massage and insufflations
• Safe handling of the AED
• Coordination with professional emergency services

The sessions include practical exercises on mannequins, realistic situational scenarios and practical advice on managing the stress and emotion associated with emergency response.

Certification recognised in Switzerland

The BLS AED SRC certificate is valid for 2 years and recognised by the health authorities and many companies. It constitutes a competence that can be used in the workplace, particularly in high-risk sectors, educational institutions and healthcare professions.

Citizen action and solidarity

By training yourself, you become an active link in the chain of survival. Each person trained increases the chances of survival of a loved one, a colleague or even a stranger. It’s a practical gesture, accessible and useful to everyone.

To find out more or register, see our complete BLS AED SRC training.

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6. The impact of your intervention on survival

In the event of cardiac arrest, every second is decisive. Thanks to rapid intervention with an AED and appropriate resuscitation techniques, a victim’s chances of survival can triple. Defibrillation within the first three minutes offers up to 70% chance of recovery without major neurological sequelae.

A vital role in the chain of survival

You’re not just a witness: you become an actor in emergency care. Your ability to alert, react, resuscitate and use a defibrillator makes the difference between a tragic outcome and a life saved.

Training as a catalyst for efficiency

The better prepared you are, the faster and more precise your movements will be. BLS AED SRC training isn’t just a course, it’s a concrete commitment to collective safety. In the workplace, at home or in the public space, being trained means assuming your share of responsibility in preventing avoidable deaths.

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Conclusion: Training to be ready to save a life

Cardiac arrest is an absolute emergency that can strike anyone, anywhere. Having an AED nearby is not enough if no one knows how to use it properly. It’s your preparation that makes the difference.

By mastering first aid and the use of a defibrillator, you become an essential player in the chain of survival. This skill, accessible to everyone, can turn a dramatic situation into a positive outcome.

Want to learn more and make a difference?

Find out about our certified BLS AED SRC courses, available throughout French-speaking Switzerland: Geneva, Lausanne, Fribourg, Neuchâtel, Valais and Jura.

To find out more or discover all the training options available, explore our complete guide to first aid training in French-speaking Switzerland.

👉 Book your session now or contact our team for an in-house session

FAQ : AED defibrillator and first aid