CPR for Cardiac Arrest
If someone is unresponsive and not breathing normally, their heart has stopped. Chest compressions started by a bystander can double or triple their chance of survival.
When to call an ambulance immediately
- No response to a loud voice or a firm shake of the shoulders
- Not breathing, or only occasional noisy gasps — agonal breathing is not breathing
- Sudden collapse, sometimes with brief jerking that can look like a fit
- Blue or grey lips and face
What to do
Work through these in order. If you are alone, put your phone on speaker so the 108 call handler can guide you while your hands stay free.
- 1
Check for danger, then for a response
Make sure the area is safe for you first. Kneel beside them, shake their shoulders firmly and shout close to each ear.
- 2
Open the airway and check breathing for 10 seconds
Tilt the head back with one hand on the forehead and lift the chin with two fingers. Look for chest movement, listen, and feel for breath on your cheek. Occasional gasping is not normal breathing. Treat it as cardiac arrest.
- 3
Call 108 and send for a defibrillator
Put your phone on speaker so the call handler can coach you. Send a second person for the nearest automated external defibrillator. Many malls, airports, offices and larger hospitals now have one.
- 4
Start chest compressions
Place the heel of one hand in the centre of the chest, on the lower half of the breastbone. Put your other hand on top and interlock your fingers. Keep your arms straight and your shoulders directly above your hands. Push down 5 to 6 cm and release fully, at a rate of 100 to 120 per minute. The beat of Stayin' Alive is almost exactly right.
- 5
Add rescue breaths only if trained and willing
Thirty compressions then two breaths, repeating. If you are untrained, unwilling, or it is a stranger, give continuous hands-only compressions instead. That alone is far better than nothing and is the recommended approach for untrained bystanders.
- 6
Use the defibrillator the moment it arrives
Switch it on and follow the spoken instructions exactly. It will not deliver a shock unless one is needed. Bare the chest, attach the pads as pictured, and make sure nobody is touching the patient while it analyses or shocks.
- 7
Do not stop
Continue until the ambulance crew takes over, the person starts breathing normally, or you are physically unable to continue. If someone else can help, swap every two minutes, because compression quality decays quickly as you tire.
Never do these
Most of these are well-intentioned and widely believed. All of them make the situation worse.
- Never delay compressions to hunt for a pulse. Bystanders are unreliable at finding one and the delay costs lives.
- Never be put off by the sound of ribs cracking. It is common, it heals, and it is survivable. Cardiac arrest without CPR is not.
- Never stop every few compressions to check whether it is working. Each interruption drops the blood pressure back to zero.
- Never use a defibrillator on a wet chest. Wipe it dry and move the person off metal or standing water.
- Never assume brief jerking movements mean a seizure rather than an arrest. Check the breathing.
Once the immediate danger has passed
- If they start breathing normally, roll them into the recovery position and keep watching, because arrest can recur.
- Stay until the ambulance arrives and tell the crew how long CPR was performed and whether a shock was delivered.
Frequently asked
I am not trained. Should I still try?
Yes. Hands-only CPR by an untrained bystander is explicitly recommended, and the 108 call handler will talk you through it. Doing nothing is the only certain way to make the outcome worse.
What if they did not actually need CPR?
A person who is conscious and breathing will push you away or object. Serious harm from compressions given unnecessarily is very rare compared with the harm of missing a cardiac arrest.
How deep is 5 to 6 cm on an adult chest?
About a third of the depth of the chest, and considerably firmer than most people expect. Shallow compressions do not circulate blood.
Reviewed and written by
Dr. Poonam Sekhon Chahal, MBBS, MEM
Senior Emergency Physician, Manipal Hospital, Patiala · Certified in ACLS, ATLS, PALS and PoCUS