How and When To Do CPR (Cardio Pulmonary Resuscitation)

The Chain of Survival

In order to maintain the oxygen supply to the body a person must be breathing, and their heart must be ‘pumping’. If either of these two functions stop, the brain and other vital organs will quickly deteriorate, and brain cells will start to die within 3 to 4 minutes. Unless urgent action is taken to circulate oxygen around the body, this will inevitably result in death.


The most common cause of cardiac arrest in adults is ‘ventricular fibrillation’. In these circumstances the best chance of restarting the heart is by using a ‘defibrillator’, which is carried on all emergency ambulances in the UK. For this reason, an emphasis is placed on summoning help and dialing 999 as soon as possible. Of course, the heart and brain must be kept oxygenated until the defibrillator arrives; so early Cardio Pulmonary Resuscitation (CPR) is vital if a casualty is to recover. These actions form the ‘links’ in the chain of survival (see diagram).

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Cardio Pulmonary Resuscitation (CPR)

The Primary survey

  • Danger – make sure it’s safe and find out what’s happened
  • Check that it is safe for you to help the casualty. Do not put yourself at risk in any way.
  • If possible remove any danger from the casualty, or if not, can you safely move the
    casualty from the danger?
  • Find out what’s happened – and make sure you are still safe.
  • Check how many casualties there are. Can you cope?

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Response – are they conscious?

  • Gently shake the shoulders and ask loudly ‘Are you alright?’
  • If there is no response, shout for help immediately, but do not leave the casualty yet.

Airway – open the airway

  • Carefully open the airway by using ‘head tilt’ and ‘chin lift’:
  • Place your hand on the forehead and gently tilt the head back.
  • With your fingertips under the point of the casualty’s chin, lift the chin to open the

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Breathing – check for normal breathing

  • Keeping the airway open, check to see if the breathing is normal. Take no more than 10 seconds to do this: 
  • Look at the chest and abdomen for movement.
  • Listen for the sounds of breathing (more than the occasional gasp).
  • Feel for air on your cheek or movement of the chest or abdomen.

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If the casualty Is breathing normally, carry out a secondary survey and place them in the recovery position.

If the casualty is not breathing normally

Ask someone to dial 999 for an ambulance or, if you are on your own, do this yourself, you may need to leave the casualty.

  • Start chest compressions as follows:
  • Place the heel of one hand in the centre of the casualty’s chest, then place the heel of your other hand on top and interlock your fingers (see diagram).
  • Position yourself vertically above the casualty’s chest with your arms straight.
  • Press down on the breastbone 5 to 6 cm then release the pressure without losing contact between your hands and the chest.
  • Ensure that pressure is not applied over the casualty’s ribs.
  • Don’t apply pressure over the upper abdomen or the bottom end of the breastbone.
  • Compression and release should take an equal amount of time.
  • Do 30 chest compressions at a rate of 100 to 120 per minute.
  • Now combine chest compressions with rescue breaths.

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Combine chest compression with rescue breaths

  • Open the airway again, using head tilt and chin lift.
  • Nip the soft part of the casualty’s nose dosed. Allow the mouth to open, but maintain chin lift.

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  • Take a normal breath and seal your lips around the casualty’s mouth.
  • Blow steadily into the casualty’s mouth, whilst watching for the chest to rise (rescue
    breath). Take about one second to make the chest rise.
  • Keeping the airway open, remove your mouth. Take a breath of fresh air and watch for the casualty’s chest to fall as air comes out.
  • Re-seal your mouth and give another rescue breath (two in total).

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  • Return your hands without delay to the correct position on the breastbone and give another 30 chest compressions (then 2 more rescue breaths).
  • Continue repeating cycles of 30 chest compressions and 2 rescue breaths.
  • Only stop to recheck the casualty if they start breathing normally, otherwise don’t interrupt resuscitation.

If your rescue breaths don’t make the chest rise effectively, give another 30 chest compressions, then before your next attempt

  • Check the casualty’s mouth and remove any visible obstruction.
  • Recheck that there is adequate head tilt and chin lift.
  • Do not attempt more than two breaths each time before returning to chest compressions.

Continue resuscitation until:

  • Qualified help arrives and takes over.
  • The casualty starts breathing normally, or
  • You become exhausted.

Resuscitation for children and babies

Recent studies have found that many children do not receive resuscitation because potential rescuers fear causing them harm. It is important to understand that it’s far better to perform ‘adult style’ resuscitation on a child (who is unresponsive and not breathing) than to do nothing at all. 

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For ease of learning and retention, first aiders can use the adult sequence of resuscitation (see previous pages) on a child or baby who is unresponsive and not breathing. The following minor modifications to the adult sequence will, however, make it even more suitable for use in children: 

  • Give five initial rescue breaths before starting chest compressions (then continue at the ratio of 30 compressions to 2 breaths).
  • If you are on your own, perform resuscitation for about 1 minute before going for help.
  • Compress the chest by about one-third of its depth.
  • For a baby under 1 year, use two fingers.
  • For a child over 1 year, use one or two hands (as needed) to achieve an adequate depth of compression (about one third of the depth).

Chest compression only resuscitation

When an adult casualty suffers a cardiac arrest, it is likely that there is residual oxygen left in the blood stream. 

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If you are unable (or unwilling) to give rescue breaths, give ‘chest compressions only’ resuscitation, as this will circulate any residual oxygen in the blood stream, so it is better than no CPR at all. 

  • If chest compressions only are given, these should be continuous at a rate of 100 per minute.
  • Stop to re-check the casualty only if they start breathing normally, otherwise do not interrupt resuscitation.
  • If there is more than one rescuer, change over every two minutes to prevent fatigue. Ensure the minimum of delay as you change over.


It is common for a patient who has stopped breathing to vomit whilst they are collapsed. This is a passive action in the unconscious person, so you may not hear or see it happening. You might not find out until you give a rescue breath (os the air comes back out of the patient it makes gurgling noises). 

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  • If the patient has vomited, turn them onto their side, tip the head back and allow the vomit to run out.
  • Clean the face of the patient then continue resuscitation, using a protective face barrier if possible.

Hygiene during resuscitation

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  • Wipe the lips clean.
  • If possible use a protective barrier such as a ‘face shield’. (This is particularly important if the patient suffers from any serious infectious disease such as TB, Hepatitis or S.A.R.S.).
  • As a last resort some plastic with a hole in it, or a handkerchief, may help to prevent direct contact.
  • If you are still in doubt about the safety of performing rescue breaths, give ‘chest compression only’ resuscitation.
  • Wear protective gloves if available and wash your hands afterwar
How and When To Do CPR (Cardio Pulmonary Resuscitation)

Book Your First Aid Training

These lessons and information do not replace actual attendance on a first aid course, getting hands on practice with your first aid skills is the best way to ensure you are a competant and capable first aider.

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