Cardiac arrest: what to tell emergency services on the phone

A cardiac arrest cuts off blood flow to the brain. Without intervention, every passing minute lowers the chances of survival by about 10 percent. Chest compressions and early defibrillation slow this decline, but neither can start before someone raises the alarm. Calling for help is not a mere formality, it is the first link in the chain of survival, the one that triggers all the others.

A trained dispatcher knows how to ask the right questions within seconds, guide the caller through lifesaving gestures and mobilise a medical team while first responders organise themselves on site. This remote coordination often saves several precious minutes before an ambulance or fire crew arrives.

Several emergency numbers exist in France, and it is not always obvious which one to use. For a cardiac arrest, the safest reflex is to call 15 or 18, both of which route automatically to emergency medical aid. The table below sums up the differences.

The dispatcher always asks the same kind of questions to assess severity and send the right resources. Give the exact address, with a landmark if possible, the number of people involved, what happened and the victim's state, conscious or not, breathing or not. A simple description, such as the person is not responding and is not breathing normally, is enough to trigger the emergency procedure.

It helps to mention whether an AED is available nearby, in a building lobby, a shop or a public venue. The dispatcher can then ask a bystander to go and fetch it while others start chest compressions. Staying calm and answering questions one by one, without hanging up, speeds up the response.

If the caller has never been trained in lifesaving gestures, the dispatcher can describe step by step how to position the hands, at what rate to press and how deep to compress the chest. This phone assistance exists precisely for untrained bystanders, it makes it possible to start effective chest compressions while waiting for help, without needing prior training.

The phone's speaker becomes a valuable tool at this point. It frees both hands for compressions while the caller keeps hearing instructions and answering questions. Placing the phone on the floor next to the victim, turning on the speaker, then following the dispatcher's guidance is the simplest method for a lone bystander.

As soon as the alarm is raised, a second person, if present, should go and fetch the nearest AED while the first stays on the phone and starts chest compressions. Most AED locator apps, fed by declarations in GéoDAE (the French national AED registry), can pinpoint the nearest device within seconds.

If no one else is present, it is better to stay with the victim, on speaker, and follow the dispatcher's instructions rather than leaving alone to search for a distant device. Immediate chest compressions take priority over defibrillation when both cannot be carried out at once.

Hanging up too soon is a common mistake, often out of reflex once compressions have begun. Yet the dispatcher remains a support throughout the response, adjusting guidance as the victim's condition evolves, warning if the AED signals a shock to deliver, and directing the response team to the exact location.

It also helps to ask a relative or someone on site to open the door or guide emergency crews through a building, a car park or an industrial site that is hard to find. These few minutes gained in orientation avoid delays once the ambulance reaches the premises.