The letters CPR stand for cardio pulmonary resuscitation. The term embraces all the procedures, from basic first aid to the most advanced medical interventions that can be used to restore the breathing and circulation in someone whose heart and breathing have stopped.
For lay people and first aiders, CPR refers to the basic first aid procedures that can be used to keep someone alive until the emergency medical services can get to the scene. The most important skills are chest compressions to pump blood around the body, and rescue breaths to provide oxygen. Rescue breaths are also known as the ‘kiss of life’.
Cardiac arrest means that the heart has stopped pumping blood around the body. This may occur for many reasons, but loss of the electrical coordination that controls the normal heartbeat is usually responsible.
The most likely cause is ventricular fibrillation, in which the normal orderly electrical signal that controls the heartbeat becomes completely disorganised and chaotic, and the heart is unable to act as a pump.
Ventricular fibrillation can be treated with a defibrillator that delivers a high energy shock to restore the heart’s normal rhythm.
No, the terms mean different things. Although ‘heart attack’ is often used to refer to a sudden cardiac arrest, this is incorrect. A heart attack (or myocardial infarction to use the medical term) occurs when an artery supplying the heart with blood becomes blocked. This usually causes chest pain and leads to damage to some of the muscle of the heart. It may cause cardiac arrest, particularly in the early stages, but this is not inevitable. The risk of cardiac arrest, however, emphasises the importance of calling for immediate help if anyone is suspected of having a heart attack, so that they can receive treatment to reduce the damage to their heart and reduce the risk of a cardiac arrest occurring.
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 medical services to reach the scene. Effective CPR more than doubles the chance of someone surviving a cardiac arrest.
Compression-only CPR describes 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-only CPR (hands only) is a useful alternative.
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 BREATHING NORMALLY. Noisy, infrequent, or gasping breaths is not normal breathing.
If you have any doubt whether someone is breathing normally or not, assume it is it NOT normal: call 999 immediately and start CPR.
The Chain of Survival describes a sequence of steps that together maximize the chance of survival following cardiac arrest.
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.
When the 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 very good with most patients making an excellent recovery.
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 for the RC (UK), the Department of Health, ambulance services and voluntary aid organisations.
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 more than 70% have been reported under these circumstances.
It is very unlikely that someone in the UK who acted in good faith when trying to help another person would be held legally liable for an adverse outcome. No such action has ever been brought against someone who performed CPR and, in general, the courts in the UK look favourably on those who go to the assistance of others.
The Resuscitation Council (UK) has published detailed guidance on the legal status of those who attempt resuscitation. This provides answers to most of the commonly asked questions on the subject.
Training in CPR is provided by many organisations, and some classes also include instruction in the use of an AED. Many 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 core principles of CPR – ventilation to provide breathing and chest compressions to support the circulation – 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. This fear is unfounded: it is far better to use the adult CPR sequence for resuscitation of a child than to do nothing. When performing chest compressions, compress the child’s chest by 1/3 to 1/2 of its depth – don’t be afraid to push hard.
Although slightly different techniques are taught to those people (particularly healthcare workers) 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.
Both adults and children may be victims of choking. The first essential is to recognise what is happening. The context may provide important clues. For example, choking is common at mealtimes, or child may have been playing with small objects.
The victim may go silent and hold or point to their throat. If the obstruction to the airway is only partial, the victim may be able to speak, cough and breathe. Encourage them to cough and clear the obstruction but keep a close eye to make certain that the situation does not get worse.
If the airway is severely obstructed, the victim will not be able to talk, but may be able to respond by nodding or shaking their head. Coughing will be ineffective, breathing will be difficult, noisy or, at worst, impossible. Without treatment the victim will ultimately lose consciousness.
Severe airways obstruction is treated by measures that aim to increase the pressure inside the chest and thereby expel the obstruction.
Fortunately, out-of-hospital cardiac arrest (OHCA) in childhood is a rare event. Studies of OHCA in children and adolescents (excluding infants under one year old) report an incidence between 3 and 9 per 100,000 per year. The rates reported in infants are generally much higher (between 11 and 72 per 100,000 infants per year). The cause in this latter group is often attributed to the Sudden Infant Death Syndrome (SIDS).
The incidence of cardiac arrest from a primarily cardiac cause (which includes cases referred to as “sudden cardiac arrest” or SCA) has been reported to be 2 – 3 per 100,000 per year in children and adolescents. SCA is more common in boys than girls, and more likely to occur during or just after sporting activity. Warning symptoms for future SCA may include previous episodes of collapse or near-collapse, dizziness, palpitations, chest pain, shortness of breath or unexplained episodes of brief seizure-like activity. Such symptoms may not always be present however and can be difficult to interpret in the setting of sporting activity, where those participating may often be pushing themselves to the point of exhaustion. A family history of cardiovascular disease and unexplained death at a young age may also be highly relevant.
Survival rates of 1.9 – 11.1% following attempted resuscitation have been reported, with good neurological outcome in many. Survival is more likely with witnessed events and a shockable rhythm on first ECG analysis -conditions often seen when an arrest occurs in a public location like a school.