Frequently asked questions based on the Resuscitation Council UK FAQ 

What is a Cardiac Arrest?

A cardiac arrest occurs when the heart stops beating effectively and normal breathing ceases. This results in the casualty becoming unresponsive and urgent intervention is required. The chances of survival are greatly increased when an AED is applied.


A cardiac arrest is an electrical problem that causes a person's heart to stop beating normally.


What is CPR?

CPR stand for cardiopulmonary resuscitation, a basic first aid procedure that can be used to keep someone alive. The most important skill is chest compressions to pump blood around the body which can be accompanied by rescue breaths to provide oxygen.


How effective is CPR?

If bystanders who witness a cardiac arrest perform CPR, sufficient blood containing oxygen will reach the brain, heart and other organs to keep the person alive for several minutes. CPR by itself will not restart the heart, but it ‘buys time’ for the emergency services to reach the scene. Effective CPR more than doubles the chance of someone surviving a cardiac arrest.


Is compression only (hands only) CPR effective?

Compression-only CPR is the performance of uninterrupted chest compressions without rescue breathing. In many adults who suffer a cardiac arrest, the heart stops abruptly; breathing will have been normal (or nearly normal) so the blood should be well oxygenated. In this situation compression-only CPR may be effective for the first few minutes after the heart stops. This may provide time for the emergency services to arrive or an AED to be collected. Ultimately the oxygen will be used up and rescue breaths are required to give the victim the best chance of resuscitation.

Where cardiac arrest is caused by lack of oxygen (as in drowning and most arrests that occur in children) compression-only CPR will be much less effective.

Chest compression alternating with rescue breaths is the ideal first aid procedure, but for untrained bystanders or those unwilling to give rescue breaths, compression or hands only CPR is a useful alternative.


How do I recognise a cardiac arrest?

When the heart stops, blood supply to the brain also stops. The victim will collapse unconscious and will be unresponsive. Breathing also stops, although it may take a few minutes to stop completely. For the first few minutes the victim may take noisy, infrequent or gasping breaths. The key features of cardiac arrest are therefore someone who is unconscious, unresponsive and not normal breathing.


If you have any doubt whether someone is breathing normally or not, call 999 immediately and start CPR. 


What happens after a cardiac arrest?

If a heart is restarted after a cardiac arrest, recovery is not immediate. Admission to hospital is always required for further treatment and investigation to establish the cause. Provided good CPR has been performed while the heart has stopped and defibrillation has been carried out promptly, the outlook is good with most patients making a recovery.


How many people survive a cardiac arrest?

In the UK fewer than 10% of all the people in whom a resuscitation attempt is made outside hospital survive. Improving this figure is a major priority.


When all the stages in the Chain of Survival take place promptly, the figures are very much better. This is possible where the arrest is recognised immediately, bystanders perform CPR, and an automated defibrillator is used before the ambulance service arrive. Survival rates in excess of 50% have been reported under these circumstances.


What is the Chain of Survival?

The Chain of Survival describes a sequence of steps that together maximize the chance of survival following cardiac arrest.


  • The first link in the chain is the immediate recognition of cardiac arrest and calling for help.
  • The second is the prompt initiation of CPR.
  • The third is performing defibrillation as soon as possible.
  • The fourth is optimal post resuscitation care


Like any chain, it is only as strong as its weakest link, so if one stage is weak the chances of successful resuscitation are compromised.


How can I be trained in CPR?

Training in CPR is provided by many organisations, and some classes also include instruction in the use of an AED. Many different kinds of training are provided, ranging from ‘hands-on’ classes with training manikins to purely internet-based distance-learning instruction. It is recommended that training should include practice on a training manikin.


The voluntary first aid organisations (for example St John Ambulance, The British Red Cross and the Royal Life Saving Society) provide instruction or local charities. There are also many private first aid training companies that provide training, and an internet search will identify those in your area. 


Is CPR done the same way on adults and children?

The core principles of CPR apply equally to children and adults.

Many children do not receive CPR because potential rescuers are not sure if there are specific methods recommended for children, and are afraid of causing harm. It is far better to use the adult CPR sequence for resuscitation of a child than to do nothing.


Although slightly different techniques (15:2) are taught to those people who have special responsibilities for the care of children, the differences are not crucial and it is far more important to do something using the techniques you have been taught. 



Ariennir achub bywyd Cymru gan Lywodraeth Cymru ac fe'i cefnogir gan rwydwaith cardiaidd Cymru, drwy'r grŵp gweithredu ar gyfer anhwylderau'r galon. Save a Life Cymru is funded by Welsh Government and supported by the Wales Cardiac Network, through the Heart Conditions Implementation Group.