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Cardiopulmonary resuscitation

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Image:CPR training-04.jpg
CPR being performed on a dummy used for training
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Cardiopulmonary resuscitation (CPR) is an emergency medical procedure for a victim of cardiac arrest or, in some circumstances, respiratory arrest.[1] CPR is performed in hospitals, or in the community by laypersons or by emergency response professionals.[2]

CPR consists of artificial blood circulation and artificial respiration[1] (i.e. chest compressions and lung ventilation).[3] CPR is generally continued, usually in the presence of advanced life support, until the patient regains a heart beat (called "return of spontaneous circulation" or "ROSC") or is declared dead.

CPR is unlikely to restart the heart, but rather its purpose is to maintain a flow of oxygenated blood to the brain and the heart, thereby delaying tissue death and extending the brief window of opportunity for a successful resuscitation without permanent brain damage. Defibrillation and advanced life support are usually needed to restart the heart.

Contents

History

Main article: History of CPR
Image:Picture of old resus methods.jpg
Sign showing old Silvester and Holger-Nielson methods of resuscitation

CPR has been known in theory, if not practice, for many hundreds or even thousands of years; some claim it is 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.[4] The procedure is repeated sixteen times per minute. This type of artificial respiration is occasionally seen in films made in the early part of the 20th century.

A second technique, called the Holger Neilson technique, described in the first edition of the Boy Scout Handbook in the United States in 1911, described a form of artificial respiration where the person was laid on their front, with their head to the side, and a process of lifting their arms and pressing on their back was utilized, essentially the Silvester Method with the patient flipped over. This form is seen well into the 1950s (it is used in an episode of Lassie during the Jeff Miller era), and was often used, sometimes for comedic effect, in theatrical cartoons of the time (see Tom and Jerry's "The Cat and the Mermouse"). This method would continue to be shown, for historical purposes, side-by-side with modern CPR in the Boy Scout Handbook until its ninth edition in 1979.

However it was not until the middle of the 20th century that the wider medical community started to recognize and promote it as a key part of resuscitation following cardiac arrest. Peter Safar wrote the book ABC of resuscitation in 1957. In the U.S., it was first promoted as a technique for the public to learn in the 1970s.[citation needed]

Use in Cardiac arrest

Image:CPR training-03.jpg
CPR training: CPR is being administrated while a second rescuer prepares for defibrillation.

The medical term for the condition in which a person's heart has stopped is cardiac arrest[5] (also referred to as cardiorespiratory arrest). CPR is used on patients in cardiac arrest in order to oxygenate the blood and maintain a cardiac output to keep vital organs alive.

Blood circulation and oxygenation are absolute requirements in transporting oxygen to the tissues. The brain may sustain damage after blood flow has been stopped for about four minutes and irreversible damage after about seven minutes. If blood flow ceases for 1 or 2 hours, the cells of the body die unless they get an adequately gradual bloodflow, (provided by cooling and gradual warming, rarely, in nature [such as in a cold stream of water] or by an advanced medical team). Because of that CPR is generally only effective if performed within 7 minutes of the stoppage of blood flow.[6] The heart also rapidly loses the ability to maintain a normal rhythm. Low body temperatures as sometimes seen in drowning prolong the time the brain survives. 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.

If the patient still has a pulse, but is not breathing, this is called respiratory arrest and artificial respiration is more appropriate. However, since people often have difficulty detecting a pulse, CPR may be used in both cases, especially when taught as first aid (see below).

First aid

CPR is part of the chain of survival, which includes early access (to emergency medical services), early CPR, early defibrillation, and early advanced care.[7] Some first aid trainers also advocate the performance of CPR as part of the choking protocol, if all else has failed.[8]

Sudden cardiac arrest is a leading cause of death, happening to approximately one in 8000 people per annum outside a hospital setting in the USA.[9] CPR can double or triple the victim's chances of survival when commenced immediately (see 'effectiveness' below). According to United States 'Annals of Emergency Medicine', only 25% of victims of a witnessed cardiac arrest are administered CPR by a bystander, with a further 33% receiving some CPR as a result of dispatcher instructions. This leaves 41% of victims receiving no CPR prior to the arrival of the emergency medical services.[10]

Rapid access to defibrillation is also vital. The most common cause of cardiac arrest outside of a hospital is ventricular fibrillation (VF), a potentially fatal arrhythmia that is usually (but not always) caused by a heart attack[citation needed] and is responsive to defibrillation. Other causes of cardiac arrest include drowning, drug overdose, poisoning, electrocution.

First aid training

CPR is taught to the general public in order to increase the chance of CPR being performed in the crucial few minutes before emergency personnel are available. Simple training is the goal of the 2005 guidelines to maximise the prospect that CPR will be performed successfully.[citation needed]

CPR is a practical skill and needs professional instruction followed up by regular practice on a resuscitation mannequin to gain and maintain full competency.[11]

In most CPR classes, a simple mnemonic is used to aid memory of the clinical approach to the unconscious patient and CPR. The most common one used worldwide is ABC which stands for Airway, Breathing and Circulation. This may be built upon with extra information (and letters) and can reach complicated levels such as AcBCDEEEFG, explained further in the main article ABC (medical).

CPR skills are not confined to medical professionals, but are regularly taught to members of the public. Widespread knowledge of CPR has a community benefit, as CPR must be applied quickly after a patients heart has stopped. Early CPR is essential to the prevention of brain damage during a cardiac arrest and increases the chance of survival.[citation needed] CPR maintains the blood flow and perfusion to the brain, buying time until a defibrillator and professional medical help arrives.

It is considered best to obtain training in CPR before a medical emergency occurs, although some modern ambulance dispatchers will talk an untrained lay rescuer through the process over the phone, while the crew is en-route. For the most effective results, hands-on training should be given by an expert. This will enable the person to perform CPR more safely and more effectively. Most organisations advocate regular retraining, in order to keep practice in the skills, and to ensure that the person is up to date with the latest guidelines, which change periodically based on the outputs from governing bodies.

First aid training, including CPR is often provided by a community organisation or charity (with or without a fee), with international providers including the Red Cross and St. John Ambulance, or more local providers such as St. Andrew's Ambulance Association in Scotland or the American Heart Association in the United States. There are also many commercial organizations, who train members of the public or workers, where the course is paid for by employers who wish, or are required by law, to have trained first aiders on site.

Guidelines

In 2005, new CPR guidelines[12][13] were published by the International Resuscitation Councils, agreed at the 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science.[14][15] The primary goal of these changes was to simplify CPR for lay rescuers and healthcare providers alike, to maximise the potential for early resuscitation. The important changes for 2005 were:[9]

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