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, emphasizes 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.

Hands only CPR

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.

• 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.

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 in excess of 50% 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 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.

Over two million people in the UK have attended Heartstart courses. These teach CPR and other emergency life-saving skills in a class lasting approximately two hours, and are free to attend. There are over 3,800 Heartstart schemes across the UK, supported by the BHF.

Many ambulance instructors also teach the general public: contact the Community Defibrillator Officer or the ambulance training school nearest you for further details.

The voluntary first aid organisations (for example St John Ambulance, St. Andrew’s Ambulance, The British Red Cross and the Royal Life Saving Society) provide instruction: contact the branch nearest you. There are also many private first aid training companies that provide training, and an internet search will identify those in your area.

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.

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.

Useful References

• Rajan S, Wissenberg M, Folke F, et al. Out-of-hospital cardiac arrests in children and adolescents: incidences, outcomes, and household socioeconomic status. Resuscitation 2015;88:12–9
  
• Johnson MA, Grahan BJH, Haukoos JS, et al. Demographics, bystander CPR, and AED use in out-of-hospital pediatric arrests. Resuscitation 2014;85:920–6
  
• Akahane M, Tanabe S, Ogawa T, et al. Characteristics and outcomes of pediatric out-of-hospital cardiac arrest by scholastic age category. Pediatr Crit Care Med 2013;14:130–6
  
• Section on Cardiology and Cardiac Surgery. Pediatric sudden cardiac arrest. Pediatrics 2012;129:e1094–102
  
• Atkins DL, Berger S. Improving outcomes from out-of-hospital cardiac arrest in young children and adolescents. Pediatr Cardiol 2012;33:474–83
  
• Meyer L, Stubbs B, Fahrenbruch C, et al. Incidence, causes, and survival trends from cardiovascular-related sudden cardiac arrest in children and young adults 0 to 35 years of age: a 30-year review. Circulation 2012;126:1363–72
  
• Nitta M, Iwami T, Kitamura T, et al. Age-specific differences in outcomes after out-of-hospital cardiac arrests. Pediatrics 2011;128:e812–20
  
• Deasy C, Bernard SA, Cameron P, et al. Epidemiology of paediatric out-of-hospital cardiac arrest in Melbourne, Australia. Resuscitation 2010;81:1095–100
  
• Park CB, Shin SD, Suh GJ, et al. Pediatric out-of-hospital cardiac arrest in Korea: A nationwide population-based study. Resuscitation 2010;81:512–7
  
• Bardai A, Berdowski J, van der Werf C, et al. Incidence, causes, and outcomes of out-of-hospital cardiac arrest in children: a comprehensive, prospective, population-based study in the Netherlands. J Am Coll Cardiol 2010;57:1822–8
  
• Kitamura T, Iwami T, Kawamura T, et al. Conventional and chest-compression-only cardiopulmonary resuscitation by bystanders for children who have out-of-hospital cardiac arrests: a prospective, nationwide, population-based cohort study. Lancet 2010;375:1347–54
  
• Atkins DL, Everson-Stewart S, Sears GK, et al. Epidemiology and outcomes from out-of-hospital cardiac arrest in children: the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. Circulation 2009;119:1484–91
  
• Ong MEH, Stiell I, Osmond MH, et al. Etiology of pediatric out-of-hospital cardiac arrest by coroner's diagnosis. Resuscitation 2006;68:335–42
  
• Donoghue AJ, Nadkarni V, Berg RA, et al. Out-of-hospital pediatric cardiac arrest: an epidemiologic review and assessment of current knowledge. Ann Emerg Med 2005;46:512–22

May 2015