TempoLife › Features › Defibrillators and cardiac arrest response › recognising-cardiac-arrest
Is this a cardiac arrest?
Two checks decide it: not responding, and not breathing normally. The noisy gasping that fools nearly everyone, why a brief seizure at the start is a cardiac sign, and why a heart attack is a different emergency.
CPR in sixty seconds
- Unresponsive and not breathing normally? Gasping is not breathing. Treat it as a cardiac arrest.
- Call 112 (113 in Norway). Speaker on, phone on the floor. Stay on the line — the dispatcher will coach you.
- Push hard and fast in the centre of the chest: 5–6 cm in an adult, 100–120 per minute, letting the chest come all the way back up.
- Send somebody else for a defibrillator. Do not go yourself unless it is seconds away. Keep compressing.
- Turn the device on and do what it says. It decides whether to shock. After a shock, go straight back to compressions.
This is a reference written for bystanders, not a diagnosis, a training course or medical advice. It cannot tell you what is wrong with a particular person, and it does not replace the dispatcher on the other end of an emergency call — they can see what is near you and they will talk you through it. If you are worried about your own heart, or about a symptom, that is a conversation with a clinician rather than a page on a website.
The whole diagnosis is two questions
A bystander does not need a pulse, a stethoscope or a diagnosis. Shake the shoulders and shout. If there is no response, tip the head back, lift the chin and look along the chest for no more than ten seconds. If the person is not responding and is not breathing normally, treat it as a cardiac arrest and start compressions. That is the entire decision, and the European Resuscitation Council states it in exactly this form so that it can be made under stress by somebody with no training at all.
The gasping that fools everybody
The single most common reason a bystander does not start CPR is that the person is still making noise. In the first minutes after the heart stops, the brainstem fires off slow, deep, snoring or fish-like gasps — agonal breathing — which can go on for several minutes and looks disturbingly like life. It is present in a large fraction of witnessed arrests. It is not breathing. Occasional, irregular, gasping, snoring or gurgling noises with long silences between them mean the brain is dying, not that the airway is working. If the pattern is not the calm regular rise and fall of a sleeping person, it is not normal breathing.
The fit at the start
Perhaps one arrest in ten begins with a short seizure — stiffening, jerking, eyes rolling back — as the brain loses its blood supply. Bystanders reasonably call it an epileptic fit and wait for it to end. The distinguishing feature is what follows: after an epileptic seizure the person breathes, often heavily, and slowly comes round. After a cardiac arrest the jerking stops and the person stays grey, limp and silent, or gasps. A first-ever seizure in an adult who then does not breathe normally is a cardiac arrest until proven otherwise.
A heart attack is not the same emergency
A heart attack is a blocked artery: the person is awake, in pain, grey, sweating, frightened. That is an ambulance call, not a CPR situation — sit them down, loosen tight clothing, do not let them walk, and stay with them, because a heart attack is the commonest thing that turns into an arrest. Cardiac arrest is the pump stopping: unconscious within seconds, no useful breathing, no purposeful movement. The words are used interchangeably in ordinary speech, and the difference decides whether your hands go on the chest.
Being wrong costs almost nothing
The fear of starting compressions on someone who is not in arrest is the main brake on bystander CPR, and it is out of proportion. A person whose heart is beating will react to hard compressions — they groan, push you away, open their eyes — and you stop. Studies of dispatcher-assisted CPR find that a proportion of patients who get bystander compressions turn out not to have been in arrest, and serious injury from that is rare. The reverse error is fatal within minutes. If you are hesitating, the correct action is to push.
Sources: European Resuscitation Council Guidelines · Käypä hoito national guideline: Elvytys (resuscitation) · checked 2026-09-08
Frequently asked questions
How do I check for a pulse?
You do not. Feeling for a carotid pulse is unreliable even for clinicians under stress and it wastes the seconds that matter, so it was removed from bystander guidance years ago. Unresponsive plus not breathing normally is the test.
What if they are gasping?
Gasping is not breathing. Slow, irregular, snoring or fish-like gasps with long pauses are a sign of cardiac arrest, not of recovery. Start chest compressions and do not stop because the gasping continues.
They had a seizure — should I still start CPR?
If the jerking has stopped and they are not breathing normally, yes. About one arrest in ten opens with a brief seizure. After an ordinary epileptic seizure the person breathes; after an arrest they do not.
What to do, right now
Hands-only CPR, in sixty seconds
Centre of the chest, 100 to 120 pushes a minute, 5 to 6 cm deep, let the chest come all the way back up, and do not stop. The rate, the depth, the fatigue problem, and a pacer that keeps you on the beat.
The emergency call, and the address problem
What the dispatcher asks, why the phone goes on speaker on the floor, how dispatcher-guided CPR works, and the single hardest question in a rural arrest: where exactly are you?
Using a defibrillator, step by step
Open it, turn it on, bare the chest, follow the voice. What the machine decides for you, what it will never do, and the one instruction people get wrong — go straight back to compressions after the shock.
Where the pads go, and what gets in the way
Right collarbone and left ribs, or front and back. Chest hair, sweat, snow, a medicine patch, a pacemaker lump, an underwired bra, a tattoo: which of these actually matter and what to do about each.
"No shock advised" does not mean stop
The most misread sentence in public-access defibrillation. What the machine has actually detected, why roughly two thirds of arrests are not shockable, and why the pads stay on and the compressions continue.
Everything on this subject
Before the emergency, there is a long quiet stretch
Blood pressure, resting heart rate, movement and sleep are the part of this you can act on for years beforehand. TempoLife keeps them in one place, free to start.