Person carrying out cpr chest compressions

What is CPR? A Guide to Resuscitation

CPR or Cardio-Pulmonary Resuscitation is a key part of all first aid courses. From the simplest Basic Life Support (BLS) course right up to the 3-day FAW, CPR is one of the first skills taught to all new or renewing first aiders.

In this easy-to-consume guide, we'll give you the information you need to understand what it is. We'll also give you the confidence that you know what to do, when and why.


Of course CPR is first and foremost a practical skill. While you'll benefit from learning about it in this guide, you also need to get 'hands-on' at a practical first aid course. That way, you'll have the confidence that you can react instinctively and do the right thing when the pressure's on.

Definition of CPR

CPR is an acronym - an abbreviation for the term Cardio-Pulmonary Resuscitation. The Collins English Dictionary defines CPR as:

“an emergency measure to revive a patient whose heart has stopped beating, in which compressions applied with the hands to the patient’s chest are alternated with mouth to mouth respiration” .

The individual elements are:

  • Cardio - meaning relating to the heart.
  • Pulmonary - meaning relating to the lungs.
  • Resuscitation - meaning to reawaken, reinvigorate or start working again.

So literally, the act of CPR is an effort to restart the flow of blood between the heart, lungs and the other organs in the body.

If you'd like to learn more about CPR

come along to one of our first aid training courses

What does CPR aim to Achieve?

When a casualty goes into cardiac arrest, their heart stops working effectively as a pump. In essence, something's gone wrong with the electrical activity that controls the heart. This causes the heart to wobble or shake (known as going into ventricular fibrillation or VF). As a result, it can't pump with the regular beat you're familiar with.

If it can't pump effectively, it won't get blood (and hence oxygen) around the body to the brain and other essential organs. Without rapid intervention, the casualty will die.

Graphic showing the difference between a healthy heart and one in cardiac arrest

Image: The heart in ventricular fibrillation (VF): The healthy heart on the left pumps regularly, causing blood to be pumped efficiently around the body. The heart on the right is in VF, meaning that it is shaking or wobbling, making it an ineffective pump. In the latter case, blood is not being pumped correctly around the body.

The purpose of CPR is to artificially keep the heart going. That keeps it pumping blood and oxygen around their system, until the underlying problem can be resolved. This will usually only be once a defibrillator has been used.

Effectively, by giving rescue breaths, you are adding oxygen to the casualty's blood. And by doing chest compressions, you are working the pump 'from outside the body'. That forces the heart to move the oxygenated blood around the body.

CPR Rules

Who Issues the Guidelines?

In the UK, Resuscitation guidelines are set by the Resuscitation Council (UK).  According to their website, they:

exist to promote high-quality, scientific, resuscitation guidelines that are applicable to everybody, and to contribute to saving life through education, training, research and collaboration. 

As part of this remit, they support research into resuscitation. They use that as evidence to influence policy and develop resuscitation guidelines. As such, they represent the gold-standard for resuscitation in the UK.

The Resuscitation Council reviews evidence regularly, and updates and publishes best-practice guidelines every 5 years. The latest update was published in 2015.

The Chain of Survival

The Resuscitation Council developed a four-step process known as the chain of survival. It describes the key elements which should be followed to increase the chances of the casualty surviving. Those steps are:

The CPR Chain of Survival

Chain of Survival, developed by the Resuscitation Council (UK)

Early recognition & call for help

It's crucial that first aider recognises the signs of cardiac arrest rapidly. Doing so enables them to call medical help as soon as possible.

So as not to delay CPR (next step), the first aider can issue instructions to another bystander to call for an ambulance. Always instruct the bystander to return to assist and to confirm that they have indeed called for an ambulance.

Early CPR

Start CPR as soon as you've recognised the signs of cardiac arrest, and you've called for medical help. This artificially operates the heart of the casualty, forcing blood around their body. If started rapidly it can extend the time that a casualty can survive while awaiting a defib or professional medical help.

Early Defibrillation

It's extremely rare that a heart will start to operate correctly through CPR alone. Instead, you'll need to use a defibrillator to shock the heart out of its 'shimmering, shaking' state. That will allow it to reset itself and start beating properly.

The earlier a defibrillator can be used, the greater the chance of survival. This is what makes increasing the number of public access defibrillators so important.

Great Post-Resuscitation Care

The quality of care that follows resuscitation will go a long way to determine the longer-term health of a cardiac arrest survivor.

If you'd like to learn more about CPR

come along to one of our first aid courses

How to do CPR

The Adult Basic Life Support Sequence

The adult BLS sequence prescribes the process which is considered to be the most effective in giving immediate first aid treatment to cardiac arrest casualties. The image below is an overview of the process:

The adult basic life support sequence

The adult Basic Life Support (BLS) sequence

When should you start CPR?

The first thing for you to note is - there's no substitute for hands-on training. This goes for everything in first aid, but in particular for CPR. And so this guide is intended as a reminder, not as a replacement for hands-on CPR training.

In first aid terms, you start CPR when you encounter a casualty who has collapsed, is unresponsive and is not breathing.

Be careful when considering whether someone is or isn't breathing. Infrequent gasps from an unresponsive casualty are not considered normal breathing. Typically, their gasps will not be effective breaths, therefore CPR you should start CPR.

The Full CPR Process

The following list is the process you should go through if you are the first person on scene and encounter someone who has collapsed and is apparently unresponsive. These instructions are for treating an adult casualty. We've listed the differences between adult CPR and child CPR at the foot of this guide.

Check for danger

make sure it's safe to approach the casualty.

Check for a response

shake them gently and shout loudly - they may just be asleep.

Open the airway

Tilt their head back & lift their chin to make sure they've a clear airway.

Look, listen and feel for NORMAL breathing

Take a maximum of 10 seconds. Gasping is not normal breathing. If you're not sure, assume they're not normal breaths.

Call for help & call 999

If there's a bystander available, get them to call 999 for an ambulance, while you start CPR. Also, tell them to fetch a defibrillator if there is one available, and instruct them to bring it back as soon as possible. If there's no-one available, call 999 yourself first, then start CPR. It's a good idea to put your phone on speakerphone, so that you can be speaking with the emergency services while doing CPR.

Start CPR - Chest Compressions

Interlock your hands on top of each other, and press down in the middle of the casualty's chest. You should do this 30 times, at a rate of 100 - 120 times per minute (2 per second).

You should be aiming to press the chest down around 5-6 cm each time.

Continue CPR - Rescue Breaths

Open the airway again by tilting the head back and lifting the chin. Then pinch the nose closed and give two of your breaths to the casualty, making a seal between your mouth and theirs. You should see their chest rise as your breaths go in. If you're unsuccessful with your breaths, don't delay. Go back to chest compressions, and return to rescue breaths in the next cycle.

Continue CPR - Repeat Compression / breaths cycle

Give a further 30 chest compressions as above, followed by 2 rescue breaths.

If a defibrillator (AED) arrives

If a helper brings a defib, get them to set it up (following the instruction images on the pads) while you continue CPR. Once it's set up, switch it on and follow its instructions.

Continue CPR cycles

Repeat the cycles until the ambulance crew arrives and takes over, until the casualty starts breathing normally and regaining consciousness, or until you are exhausted. If an assistant is available to help you, swap over every 2 minutes or so, so that you both have enough energy to continue.

If you'd like to learn more about CPR

come along to one of our first aid courses

A Few CPR-Related Statistics

Each year, the ambulance service responds to around 60,000 suspected cases of cardiac arrest.

According to NHS England, resuscitation is attempted in fewer than half of those cases (around 28,000 in 2014). This disparity mainly resulted from the casualty already being dead for a period of time or because no-one had attempted CPR before the emergency services arrived. In both cases, there was no chance of reviving the casualty, so no CPR was attempted.

Even when ambulance staff do attempt resuscitation, fewer than 10% survive long enough to leave hospital alive.

Survival Following out-of-hospital cardiac arrest

A team led by Marieke Blom ran a study between 2006 and 2012 investigating survival after out-of-hospital cardiac arrests. It suggested that training more bystanders & increasing community use of defibrillators will at least double the expected survival rate. They estimated that doing so could save thousands of lives each year. Encouragingly, over the course of the study, out-of-hospital defibrillator use increased by nearly 300%. That in turn reduced the average time to defibrillation from 9.9 minutes to 8 minutes.

And we do need to increase the numbers of bystanders who are happy to perform CPR. A BHF poll in 2014 found that 46% of people would be reluctant to help out for fear of causing harm. 22% also said they wouldn't help because of a fear of being sued and over 40% said they simply lacked the skills to be able to help.

But if you need an incentive to learn CPR, bear in mind that statistics show 80% of all cardiac arrests occur at home, and only 20% out in public.

Other CPR-related Questions

Doing CPR

Why is CPR Important?

If someone's heart has stopped beating effectively (or at all), blood and oxygen stop circulating around the body, and hence oxygen stops reaching the brain.

The brain can only last without oxygen for between 3 and 9 minutes (usually stated as around 6 minutes) before irreversible damage is done to it.

Carrying out CPR helps to move oxygenated blood around the body, including to the brain, while the emergency services are on their way.

Essentially, CPR buys time for casualty and for the emergency services to arrive to treat them. This increases their chances of survival, and reduces the potential damage to the brain.

As a result, CPR is a key component of first aid training including the full first aid at work range of courses, Paediatric first aid (for those looking after younger children) as well as our suit of CPR courses for Dental Practices.

Why are Defibrillators important in CPR?

It's extremely unlikely that CPR alone will restart a casualty's heart. That's where defibrillators come in. Defibrillators (otherwise known as AEDs, defibs or Automated External Defibrillators) can interrupt an ineffective heart rhythm (known as ventricular fibrillation or VF), and can cause the heart to restart it's own natural pace-making rhythm.

A defibrillator will only work when the heart is in a VF or VT (Ventricular Tachycardia) rhythm, and so cannot restart a 'dead heart'. Equally, it cannot cause damage to or stop a healthy heart. VT is where the heart is pumping so quickly it cannot refill properly, and so does not pump blood effectively.

Early CPR intervention combined with early use of a defib dramatically increase the chances of recovery of a cardiac arrest patient.

What are the differences between giving CPR to an adult, child or infant?

There are minor differences recommended between the adult, child and infant resuscitation sequences.

Once you've checked for and identified that the infant or child is not breathing, give 5 initial rescue breaths before starting the first set of chest compressions. 

When compressing the chest, do so for about 1/3 of the total depth (around 4cm for infants and 5 cm for children).

With the exception of the above, the sequence is the same for children as for adults. And once children are around small adult size, you should treat them as adults for CPR purposes anyway.

Remember, if in doubt, it's better to do something than nothing - so if you're not sure, just use the adult sequence that you know.

Will CPR restart a stopped heart?

As stated above, it's very unlikely that CPR alone will start a heart that's not working properly. Instead, it buys time for a defib to arrive and be used, or for the emergency services to arrive.

Where on the chest should CPR be done?

Link your fingers, with both palms placed on top of one another. Place the heel of your lower hand in the centre of the chest and press down 5-6cm, at a speed of around 100 - 120 beats per minute.

Are breaths necessary in CPR?

CPR can be done without breaths.

General advice is, if you are trained then you should include breaths in the CPR process, in the ratio of 30 compressions to 2 breaths.

However, if you are not trained, or are unable or unwilling to use breaths as part of CPR, then the advice is to do 'compression-only CPR'. Although this will be less effective than CPR with breaths, it is much better than standing by and doing nothing at all.

Are gasps normal breathing in CPR?

No. If someone is unresponsive and taking strange, occasional gasps instead of proper breaths, they are not breathing properly. In this case, you should assume that they are suffering a cardiac arrest, and begin CPR procedure.

If you'd like to learn more about CPR

come along to one of our first aid courses

Causing Injury

Can you break bones when giving CPR?

Yes, you can.

When doing CPR, it is possible to break ribs and perhaps even the breastbone. CPR does, out of necessity, require a good deal of force to compress the chest enough to pump blood around the body.

However, if you do break a rib, you must ignore it and continue to do CPR. Without CPR, the casualty is not going to survive long enough for the paramedics to arrive.

Can CPR cause a collapsed lung?

It's possible.

If one or more ribs are broken during CPR, it is possible for them to puncture a lung, causing it to collapse.

Again however, without CPR, the casualty is not going to survive, and so it's better to do CPR and give them a chance of survival.

Can CPR cause internal bleeding?

Doing CPR can cause injury to the casualty, including causing a bleed. However the person is already technically dead, and so doing nothing is much worse than attempting CPR.

Can CPR cause death

Doing CPR is not going to cause death. If the casualty is suffering from Cardiac Arrest and CPR is required, they have effectively already died. You cannot make things worse. Doing CPR on them has a chance of improving things, and keeping their brain alive long enough for an AED or the Paramedics to arrive to help.

Can I be sued for causing injury while doing CPR?

As of the time of writing, we are unaware of any cases in the UK of someone being successfully sued for carrying out 'good samaritan CPR'. This is because any injury caused is unintentional and occurs while the good samaritan is attempting to save the casualty's life. 

The Social Action, Responsibility and Heroism Act 2015 (otherwise known as the Sarah Act) was introduced to direct courts in cases of alleged negligence or breach of statutory duty to look at the circumstances in which a good samaritan may have caused injury to a casualty.

In particular, it directs the court to look at whether they were acting in the interests of the casualty or of society, and whether they were acting responsibly or heroically. While it doesn't change the law as such, it further decreases the likelihood of a good samaritan being successfully prosecuted.

CPR Training

Should CPR be taught in schools?

Absolutely - yes! We support the BHF's campaign to make the teaching of CPR skills mandatory in secondary schools. In fact, it's never to early to learn.

The BHF commissioned a poll to find out how the public felt about this issue, and received an overwhelmingly positive response, with over 82% of the public supporting training in schools.

The justification is easy. In Norway, where CPR skills are taught as part of the curriculum, cardiac arrest survival rates are double those in the UK. Teaching CPR is increasing elsewhere around the world too. It's now a graduation requirement in many US states, and is taught in several European countries and Australian states.

Update 2019: The Education Secretary Damien Hinds confirmed on 3rd January 2019 the government's commitment to include basic first aid (which includes CPR training) in the national curriculum for state funded schools from 2020.

Which is better CPR or BLS?

Basic life support usually refers to the assistance that a first person on scene would give to a casualty who is suffering with breathing or heart problems. As such, BLS training includes several different first aid procedures including CPR, recovery position and treatment for choking.

So a BLS course is broader than CPR training, as it contains CPR training as one of its elements.

Who teaches CPR classes?

A range of training providers can teach CPR classes. They include some hospitals, the voluntary organisations (Red Cross and St John Ambulance), the Resuscitation Council (as part of ILS and ALS courses) and private training organisations.

CPR is taught both as a standalone course (usually as an annual refresher for healthcare professionals) and as part of formal regulated first aid courses such as FAWs and EFAWs and paediatric first aid.

We would recommend going to a provider who offers regulated courses, as they have to undertake regular quality audits. That gives you an extra level of security that the trainers have the level of skill and training to deliver top quality courses.

Is free online CPR training any good?

Undergoing some form of training is generally better than no training at all. And free (or paid) online courses will typically contain accurate information on how to carry out CPR.

A particularly good resource is the Lifesaver App - a game from the Resuscitation Council. It's an interactive film which presents you with several emergency situations. You must decide how to react to give the casualty the best chance of survival.

However, when you're called upon to do CPR, you're likely to be in a highly pressured situation, both due to the responsibility of what you're doing and the time pressure that you'll be under. And when you consider that 80% of cardiac arrests take place in and around the home, there's likely to be huge emotional pressure too.

At a time like that, you're going to want muscle-memory to kick in, as well as your training. You're going to want to have physically practised checking for danger, assessing whether an unconscious casualty is indeed unresponsive and not breathing. You're going to want to have practised CPR, and setting up and using a defib.

So while online CPR training may be an attractive, cheap and even free option, we'd always recommend taking a practical, face-to-face course. Even if you alternate between an online course and a practical one, don't leave yourself reliant on something you read online or in a book, or on this blog post. Get yourself properly trained by a professional.

If you'd like to learn more about CPR

come along to one of our first aid courses

To find out more

If you'd like to find out more, take a look at some of the excellent resources below:

Please note:

The information included in this guide, and on our website as a whole is for guidance only. It does not replace the need for face-to-face first aid training.

All reasonable efforts have been made to ensure that the information contained herein is accurate. However it is possible that errors exist, or have been introduced over time as best practice changes.

Please ensure that you've undergone proper face-to-face first aid training, and kept your skills up-to-date instead of relying solely on online resources.

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