Cardiopulmonary resuscitation

Cardiopulmonary resuscitation (CPR) is an emergency first aid protocol for an unconscious person on whom neither breathing nor pulse can be detected.

The medical term for a patient whose heart has stopped is cardiac arrest (also referred to as cardiorespiratory arrest), in which case CPR is used. If the patient still has a pulse, but is not breathing, this is called respiratory arrest and Rescue breathing is used.

The most common treatable cause of cardiac arrest outside of a hospital is a heart attack leading to a heart rhythm disturbance. Cardiac arrest may be caused by a number of events, including drowning, drug overdoses, poisoning, electrocution and many other conditions.

Many countries have official guidelines on how CPR should be provided, and these naturally override the general description of CPR in this article.

Beginning in 2004, some jurisdictions began receiving automated CPR machines such as the AutoPulse, which will do the necessary chest compressions automatically and allow the first responders to attend to other needs for the affected patient.

In 2005, new CPR guidelines were published with input from the American Heart Association, the Canadian Heart and Stroke Foundation and European Resuscitation Council, with the primary goal of simplifying CPR for laypersons and healthcare providers alike.

Importance

Heart action and respiratory effort are absolute requirements in transporting oxygen to the tissues. One of the main organs to suffer from oxygen starvation is the brain, which may sustain damage after four minutes and irreversible damage after about seven minutes. The heart also rapidly loses the ability to maintain a normal rhythm. Following cardiac arrest, effective CPR enables enough oxygen to reach the brain to delay brain death, and allows the heart to remain responsive to defibrillation attempts.

CPR is commonly taught to the general public as these may be the only ones present in the crucial few minutes before emergency personnel are available. If administered properly it can save lives but when done badly or inappropriately it can interfere with life saving operations later. Sometimes CPR should not be attempted, particularly if other persons are injured and need immediate help. CPR takes a lot of effort and may keep care providers from helping others. See triage.

Effectiveness

CPR is almost never effective if started more than 15 minutes after collapse because permanent brain damage has probably already occurred. A notable exception is cardiac arrest occurring in conjunction with exposure to very cold temperatures. Hypothermia seems to protect the victim by slowing down metabolic and physiologic processes, greatly decreasing the oxygen needed by tissues. There are cases where CPR, defibrillation, and advanced warming techniques have revived hypothermia victims after over 30 minutes or longer. A patient cannot be pronounced dead before he has been brought back to a normal temperature by appropriate means.

Used alone, few patients will make a complete recovery, and those that do survive often develop serious complications. Estimates vary, but many organizations stress that CPR does not "bring anyone back", it simply preserves the body for defibrillation and advanced life support.

In 2005, new resuscitation guidelines were published jointly by the International Liaison Committee on Resuscitation (ILCOR) and several regional bodies (Such as the American Heart Association, the European Resuscitation Council, & the Resuscitation Council (UK)), designed to increase the effectiveness of CPR. They found that in order for CPR to be most effective:

There should be minimal interruptions to chest compressions
Compressions should be of adequate depth
Compressions should be given at a fast rate

It is also considered by ILCOR and a number of national and international bodies that in order for CPR to be effective, the guidelines must be simple and easy to remember, as the biggest barrier to providing CPR is thought to be the confidence of the rescuer.

CPR training

CPR is a practical skill and needs professional instruction followed up by regular practice on a resuscitation mannequin to gain and maintain full competency. Training is available through many commercial, volunteer and government organizations worldwide.

CPR training is not confined to the medical professionals. To be effective, CPR must be applied almost immediately after a patient's heart has stopped. Early CPR on the scene of an incident is essential to the prevention of brain damage during a cardiac arrest. Blood flow and air supply to the brain and other major organs is maintained until a defibrillator and professional medical help arrives. Almost anyone is able to perform CPR with training, and health organizations advocate the development of CPR skills throughout the general public.

It is best to obtain training in CPR before a medical emergency occurs. One needs hands-on training by experts to perform CPR safely, and guidelines change, so that training should be repeated every one or two years. Training in first aid is often available through community organizations such as the Red Cross and St. John Ambulance. In many countries in the Commonwealth of Nations, St. John Ambulance provides CPR training. In Scotland, St. Andrew's Ambulance Association provides first aid training. In the United States, the American Heart Association and American CPR Training also offer CPR training,

History

CPR has been known in theory, if not practice, for many hundreds, if not thousands, of years; some claim it is even described in the Bible, discerning a superficial similarity to CPR in a passage from the Books of Kings (II 4:34), wherein the Hebrew prophet Elisha warms a dead boy's body and "places his mouth over his". In the 19th century, doctor H. R. Silvester described a method (The Silvester Method) of artificial respiration in which the patient is laid on their back, and their arms are raised above their head to aid inhalation and then pressed against their chest to aid exhalation. The procedure is repeated sixteen times per minute. This type of artificial respiration is occasionally seen in movies made in the early part of the 20th century.

However it wasn't until the middle of the 20th century that the wider medical community started to recognise and promote it as a key part of resuscitation following cardiac arrest. Peter Safar wrote the book ABC of resuscitation in 1957. In the US, it was first promoted as a technique for the public to learn in the 1970s. Early marketing efforts oversold the effectiveness of CPR in rescuing heart attack and other victims, and this misperception continues even today.

Myths and popular culture

CPR is often portrayed in movies and television as being highly effective in resuscitating a person who is not breathing and has no circulation. A 1996 study by the New England Journal of Medicine showed that CPR success rates in television shows was 75% ^*. The reality is that CPR administered outside hospitals has a near 0% success rate on its own, and is most importantly used to sustain oxygen supply to the brain until specialized medical equipment and personnel can reach the scene (see defibrillator). Very few victims regain regular heartbeat from CPR alone. If someone "regains" signs of circulation after only bystander CPR was performed, it is usually because the victim was not actually in true cardiac arrest. Several medical studies have indicated that CPR is inaccurately portrayed in the media: it is commonly described on television and movies as the definitive treatment of cardiac arrest and leads the general public to believe that CPR alone can have an extraordinary resuscitation save rate.

The truth remains that while CPR is an integral part of the resuscitation process, it cannot be used to replace other resuscitative adjuncts such as defibrillation, airway management and intravenous drug therapy. The most common myth associated with CPR is that it restarts the heart; it does not. The rhythmic breathing and chest compressions provide some amount of air and circulation to a victim, allowing more time for help to arrive. During cardiac arrest the heart enters into several rhythm types that do not sustain proper blood circulation. A common cardiac arrest rhythm is ventricular fibrillation, which is caused by disorganized electrical activity that prevents the heart from beating properly. A defibrillator is needed to shock the heart to correct this rhythm. This shock stuns the out-of-sync myocardiocytes, in the hopes the normal cardiac pacemaker cells will re-establish a proper heart rhythm, and thus, a heartbeat. CPR only acts as a substitute for the heart's pumping and is not nearly as effective.

Many rescuers who have performed CPR — healthcare provider and layperson alike — have indicated their surprise about what it is really like to perform CPR. Some note that they were unprepared for cartilage separation (considered to be normal in some cases) during chest compression, and believed that they were performing CPR incorrectly (when they were in fact doing it correctly). In order to perform CPR, chest compressions must go very deep and it is not uncommon to crack ribs. Others note that they were shocked when patients vomited, a stark contrast to the clean environment CPR was taught to them in classes (although in modern American Red Cross classes pupils are warned about the possibility of vomiting and the importance of using barriers, such as gloves, against bodily fluids - especially blood). In some cases, rescuers blamed themselves when patients were not resuscitated, believing it was their fault for doing "CPR incorrectly" or "not doing CPR well enough". It is considered important to educate the general public and healthcare professionals that CPR is never guaranteed to save someone's life. Even if CPR is performed perfectly, the person in cardiac arrest may still not be resuscitated. The American Heart Association notes that "some hearts are too sick to be saved" and reflects the reality that CPR is not a cure-all but merely an important part of the resuscitation process.

References

Weisfeldt ML. Public access defibrillation: good or great? BMJ USA 2004;328:E271-E272. Fulltext. PMID 14988214.
Resuscitation Guidelines 2005. Resuscitation Council (UK), 2005. ISBN 1903812100. Online version.
Ganong WF. Review of Medical Physiology 19th ed. Appleton & Lange, 1999. ISBN 0838584497

Organizations and links for CPR training

External links

UK Resuscitation Council 2005 guidelines in plain English
European Resuscitation Council European 2005 guidelines
Free online CPR video for Quick CPR Review
American Heart Association 2005 guidelines - gives scientific detail.
Overview of changes from 2000 to 2005 guidlines
Learn CPR - Basic description of CPR procedure, incorporating 2005 update

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