Cardiopulmonary resuscitation (CPR)

Cardiopulmonary resuscitation (CPR) is an emergency procedure for manually preserving brain function until further measures to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest. It is indicated in those who are unresponsive with no breathing or abnormal breathing, for example, agonal respirations.

Per the International Liaison Committee on Resuscitation guidelines, CPR involves chest compressions at least 5 cm (2 in) deep and at a rate of at least 100 per minute to pump blood through the heart and thus the body. The rescuer may provide breaths by either exhaling into the subject's mouth or nose or a device that pushes air into the subject's lungs; externally providing ventilation is termed artificial respiration. Current recommendations place emphasis on high-quality chest compressions over artificial respiration; a simplified CPR method involving chest compressions only is recommended for untrained rescuers.

Medical uses: CPR is indicated for any person who is unresponsive with no breathing, or who is only breathing in occasional agonal gasps, as it is most likely that they are in cardiac arrest. If a person still has a pulse, but is not breathing (respiratory arrest) artificial respirations 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 health care professionals the option to check a pulse. In those with cardiac arrest due to trauma CPR is considered futile in the pulseless case, but still recommended for correctible causes of arrest.

Methods: In 2010, the American Heart Association and International Liaison Committee on Resuscitation updated their CPR guidelines. The importance of high quality CPR (sufficient rate and depth without excessively ventilating) was emphasized. The order of interventions was changed for all age groups except newborns from airway, breathing, chest compressions (ABC) to chest compressions, airway, breathing (CAB). An exception to this recommendation is for those who are believed to be in a respiratory arrest (drowing etc). The most important aspect of CPR are: few interruptions of chest compressions, a sufficient speed and depth of compressions, completely relaxing pressure between compressions, and not ventilating too much.

Standard

A universal compression to ventilation ratio of 30:2 is recommended. With children, if at least 2 trained rescuers are present a ratio of 15:2 is preferred. In newborns a rate of 3:1 is recommended unless a cardiac cause is known in which case a 15:2 ratio is reasonable. If an advanced airway such as an endotracheal tube or laryngeal mask airway is in place delivery of ventilations should occur without pauses in compressions at a rate of 8–10 per minute. The recommended order of interventions is chest compressions, airway, breathing or CAB in most situations, with a compression rate of at least 100 per minute in all groups. Recommended compression depth in adults and children is at least 5 cm (2 inches) and in infants it is 4 cm (1.5 inches. As of 2010 the Resuscitation Council (UK) still recommends ABC for children. As it can be difficult to determine the presence or absence of a pulse the pulse check has been removed for lay providers and should not be performed for more than 10 seconds by health care providers. In adults rescuers should use two hands for the chest compressions, while in children they should use one, and with infants two fingers (index and middle fingers).

Complications: Whilst CPR is a last resort intervention, without which a patient without a pulse will certainly die, the physical nature of how CPR is performed does lead to complications that may need to be rectified. Common CPR complications are rib fractures, sternal fractures, bleeding in the anterior mediastinum, heart contusion, hemopericardium, upper airway complications, damage to the abdominal viscus - lacerations of the liver and spleen, fat emboli, pulmonary complications - pneumothorax, hemothorax, lung contusions.

The most common injuries sustained from CPR are rib fractures, with literature suggesting an incidence between 13% and 97%, and sternal fractures, with an incidence between 1% to 43%. Whilst these iatrogenic injuries can require further intervention (assuming the patient survives the cardiac arrest), only 0.5% of them are life threatening in their own right.

The type and frequency of injury can be affected by factors such as gender and age. For instance, women have a higher risk of sternal fractures than men, and risk for rib fractures increases significantly with age. Children and infants have a low risk of rib fractures during CPR, with an incidence less than 2%, although when they do occur, they are usually anterior and multiple.

Where CPR is performed in error by a bystander, on a patient who is not in cardiac arrest, only around 2% suffer injury as a result (although 12% experienced discomfort).