TempoLife › Features › Defibrillators and cardiac arrest response › rescue-breaths
Compression-only or 30:2?
When breaths change the outcome and when they cost more than they give. The adult rule, the exceptions that override it, and how to give a breath that actually goes in.
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 adult default
An adult who collapses suddenly from a cardiac cause still has oxygen dissolved in the blood; the problem is that nothing is moving it. For the first minutes, chest compressions alone circulate that oxygen well, and the evidence behind compression-only CPR for untrained bystanders is strong enough that every dispatcher protocol in this region defaults to it. If you are trained, willing and able, thirty compressions to two breaths is still the standard and is preferable in a longer resuscitation. If you are not, push and do not feel you are doing a lesser version.
Where breaths stop being optional
Some arrests are caused by the breathing stopping first, and in those the blood is already oxygen-depleted before the heart quits. That is the picture in drowning, in choking, in smoke inhalation, in opioid overdose, and in almost all cardiac arrests in children and babies. In those situations ventilation is part of the treatment rather than an optional extra, and the guidelines change accordingly: five initial rescue breaths before compressions in a child or a drowned person, then a 30:2 cycle — 15:2 if two trained rescuers are working on a child.
How to give a breath that works
Tilt the head back with one hand on the forehead and lift the chin with two fingers — this is what opens the airway, and most failed breaths are failed head tilts rather than failed technique. Pinch the nose closed, take a normal breath, seal your mouth over theirs and blow steadily for about a second while watching for the chest to rise. Let it fall, then give the second breath. Two attempts maximum, then straight back to compressions: never spend more than about ten seconds away from the chest.
Infants, barriers and the reality of mouth-to-mouth
For a baby, cover the mouth and nose together with your mouth and use small puffs — an infant's lungs hold very little and a full adult breath is too much. Pocket masks and face shields make bystanders far more willing and are worth having in a first-aid kit and a car. If there is no barrier and you are unwilling to do mouth-to-mouth on a stranger, compression-only CPR is a good answer for an adult; for a child, mouth-to-mouth from an unwilling rescuer is still better than compressions alone.
Do not over-ventilate
The commonest ventilation error in trained hands is blowing too hard, too fast and too often. It raises the pressure in the chest, reduces the blood returning to the heart, and pushes air into the stomach, which brings up vomit. Steady, one second, just enough for the chest to visibly rise. If the chest does not rise, re-tilt the head rather than blowing harder.
| Situation | Pattern | Why |
|---|---|---|
| Adult, sudden collapse, untrained rescuer | Compressions only | Blood still carries oxygen; simplicity wins |
| Adult, trained and willing rescuer | 30 compressions : 2 breaths | Adds ventilation without losing compression time |
| Child or infant | 5 initial breaths, then 30:2 (15:2 with two trained rescuers) | Arrest is usually caused by breathing failure |
| Drowning | 5 initial breaths, then 30:2 | Oxygen was gone before the heart stopped |
| Suspected opioid overdose | Breaths matter — 30:2 if you can | Respiratory arrest comes first |
| Smoke, choking or asphyxia | Breaths matter — 30:2 if you can | Same mechanism: hypoxia first |
Sources: European Resuscitation Council Guidelines · Käypä hoito national guideline: Elvytys · checked 2026-09-08
Frequently asked questions
Is compression-only CPR really as good?
For an adult who collapses suddenly in front of you, in the first minutes, it performs comparably and it is far more likely to actually be done. In children, drowning and overdose the picture is different and breaths matter.
What if the chest does not rise when I blow?
Re-tilt the head and lift the chin again — a poorly opened airway is the usual cause. Try once more, then return to compressions; never make more than two attempts before compressing again.
Can I catch something from mouth-to-mouth?
Transmission of serious infection from rescue breathing is very rare and no case of HIV transmission this way is documented. A pocket mask removes the concern entirely and costs very little.
What to do, right now
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.
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.
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.