Cardiopulmonary resuscitation
Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation, or mouth to mouth in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest. It is recommended for those who are unresponsive with no breathing or abnormal breathing, for example, agonal respirations.[1]
"CPR" redirects here. For other uses, see CPR (disambiguation).Cardiopulmonary resuscitation
CPR involves chest compressions for adults between 5 cm (2.0 in) and 6 cm (2.4 in) deep and at a rate of at least 100 to 120 per minute.[2] The rescuer may also provide artificial ventilation by either exhaling air into the subject's mouth or nose (mouth-to-mouth resuscitation) or using a device that pushes air into the subject's lungs (mechanical ventilation). Current recommendations place emphasis on early and high-quality chest compressions over artificial ventilation; a simplified CPR method involving only chest compressions is recommended for untrained rescuers.[3] With children, however, 2015 American Heart Association guidelines indicate that doing only compressions may actually result in worse outcomes, because such problems in children normally arise from respiratory issues rather than from cardiac ones, given their young age.[1] Chest compression to breathing ratios is set at 30 to 2 in adults.
CPR alone is unlikely to restart the heart. Its main purpose is to restore the partial flow of oxygenated blood to the brain and heart. The objective is to delay tissue death and to extend the brief window of opportunity for a successful resuscitation without permanent brain damage. Administration of an electric shock to the subject's heart, termed defibrillation, is usually needed to restore a viable, or "perfusing", heart rhythm. Defibrillation is effective only for certain heart rhythms, namely ventricular fibrillation or pulseless ventricular tachycardia, rather than asystole or pulseless electrical activity, which usually requires the treatment of underlying conditions to restore cardiac function. Early shock, when appropriate, is recommended. CPR may succeed in inducing a heart rhythm that may be shockable. In general, CPR is continued until the person has a return of spontaneous circulation (ROSC) or is declared dead.[4]
Medical uses[edit]
CPR is indicated for any person unresponsive with no breathing or breathing only in occasional agonal gasps, as it is most likely that they are in cardiac arrest.[5]: S643 If a person still has a pulse but is not breathing (respiratory arrest), artificial ventilations may be more appropriate, but due to the difficulty people have in accurately assessing the presence or absence of a pulse, CPR guidelines recommend that lay persons should not be instructed to check the pulse, while giving healthcare professionals the option to check a pulse.[6] In those with cardiac arrest due to trauma, CPR is considered futile but still recommended.[7] Correcting the underlying cause such as a tension pneumothorax or pericardial tamponade may help.[7]
Pathophysiology[edit]
CPR is used on people in cardiac arrest to oxygenate the blood and maintain a cardiac output to keep vital organs alive. Blood circulation and oxygenation are required to transport oxygen to the tissues. The physiology of CPR involves generating a pressure gradient between the arterial and venous vascular beds; CPR achieves this via multiple mechanisms.[8] The brain may sustain damage after blood flow has been stopped for about four minutes and irreversible damage after about seven minutes.[9][10][11][12][13] Typically if blood flow ceases for one to two hours, then body cells die. Therefore, in general CPR is effective only if performed within seven minutes of the stoppage of blood flow.[14] The heart also rapidly loses the ability to maintain a normal rhythm. Low body temperatures, as sometimes seen in near-drownings, prolong the time the brain survives. Following cardiac arrest, effective CPR enables enough oxygen to reach the brain to delay brain stem death, and allows the heart to remain responsive to defibrillation attempts.[15] If an incorrect compression rate is used during CPR, going against standing American Heart Association (AHA) guidelines of 100–120 compressions per minute, this can cause a net decrease in venous return of blood, for what is required, to fill the heart.[16] For example, if a compression rate of above 120 compressions per minute is used consistently throughout the entire CPR process, this error could adversely affect survival rates and outcomes for the victim.[16]
Prevalence[edit]
Chance of receiving CPR[edit]
Various studies show that in out-of-home cardiac arrest, bystanders in the US attempt CPR in between 14%[143] and 45%[144] of the time, with a median of 32%.[145] Globally, rates of bystander CPR reported to be as low as 1% and as high as 44%.[146] However, the effectiveness of this CPR is variable, and the studies suggest only around half of bystander CPR is performed correctly.[147][148] One study found that members of the public having received CPR training in the past lack the skills and confidence needed to save lives. The report's authors suggested that better training is needed to improve the willingness to respond to cardiac arrest.[145] Factors that influence bystander CPR in out-of-hospital cardiac arrest include:
Society and culture[edit]
Portrayed effectiveness[edit]
CPR is often severely misrepresented in movies and television as being highly effective in resuscitating a person who is not breathing and has no circulation.[159]
A 1996 study published in the New England Journal of Medicine showed that CPR success rates in television shows was 75% for immediate circulation, and 67% survival to discharge.[159] This gives the general public an unrealistic expectation of a successful outcome.[159] When educated on the actual survival rates, the proportion of patients over 60 years of age desiring CPR should they have a cardiac arrest drops from 41% to 22%.[160]
On animals[edit]
It is feasible to perform CPR on animals, including cats and dogs. The principles and practices are similar to CPR for humans, except that resuscitation is usually done through the animal's nose, not the mouth. CPR should only be performed on unconscious animals to avoid the risk of being bitten; a conscious animal would not require chest compressions. Animals, depending on species, may have a lower bone density than humans and so CPR can cause bones to become weakened after it is performed.[180]
Research[edit]
Cerebral performance category (CPC scores) are used as a research tool to describe "good" and "poor" outcomes. Level 1 is conscious and alert with normal function. Level 2 is only slight disability. Level 3 is moderate disability. Level 4 is severe disability. Level 5 is comatose or persistent vegetative state. Level 6 is brain dead or death from other causes.[181]