Cardiopulmonary resuscitation, commonly known as CPR, is an emergency procedure performed in an effort to preserve brain function and manually pump blood through to the body’s vital organs, until further measures are taken to restore spontaneous circulation. CPR is indicated in cardiac arrest patients, but may also be performed on patients with an unresponsive presentation or those experiencing agonal breaths or severe and prolonged arrhythmias such as bradycardia or tachycardia. The first acknowledgement of a form of CPR was in the 19th century; however, the medical population did not know the true benefits of chest compressions and artificial respirations following cardiac arrest until the mid-20th century. Today, it is widely encouraged and used by both medical professionals as well as bystanders witnessing a cardiac arrest.
Manual cardiopulmonary resuscitation has two parts: chest compressions and ventilation. A chest compression is described as the patient’s chest being forced down, therefore putting pressure on the heart to push out blood, and then recoiling back up, which increases the volume in the chest cavity and allows blood to flow back in to the heart. To perform adequate chest compressions, the provider must stack his hands and interlock his fingers, and place the lower part of the palm over the patient’s xyphoid process, near the end of the sternum. The provider will then press down on the patient’s chest with firm pressure, and then release. Ventilation is the second part of CPR and is the process of pushing air into the patient’s lungs either by exhaling into the patient’s mouth or nose, or by using a device to deliver oxygen.
The recommended ratio of compressions to ventilations varies between adults and children, and whether or not the person performing the CPR is a trained healthcare professional. In standard adult CPR, the recommended ratio is 30 compressions (at a rate approx 100 p/min), pause to give 2 breaths, and resume compressions. If it is 2-rescuer CPR and an advanced airway is present, such as a nasopharyngeal airway adjunct or an endotracheal tube, breaths are given every five to six seconds by the first provider, with the second provider continuing to perform compressions. The American Heart Association recommends changing the ratio to 15 compressions for every two breaths in infant and pediatric CPR. The reason for this change is that the majority of pediatric cardiac arrest is caused by a previous respiratory arrest. The goal then is to restore spontaneous circulation by providing the body with a supply of oxygen that was lacking before the patient arrested. In adults, one compression should be at least five centimeters deep; in children, however, the compression should press halfway down the diameter of the chest cavity.
An alternate method of CPR is called compression-only, which means that the provider is compressing the chest without artificial respiration. Compression-only CPR is recommended for lay people who are not confident in their ability to perform CPR, assuming the patient has not drowned or overdosed. The patient should also be an adult; compression-only CPR is not effective in children. Another type of CPR is called internal CPR is a type of CPR provided only by healthcare professionals in a hospital setting where the patient’s chest has been opened via surgical incision. The provider may reach his hand into the chest and manually squeeze the heart.
The healthcare industry has many devices and techniques to assist a person in providing adequate CPR. Timing devices, or metronomes, are available on some ambulances or in hospitals. However, many providers have been known to quietly sing songs to themselves, such as “Another One Bites the Dust” or “Stayin’ Alive,” because the beat of both those melodies is 100 beats per minute. Recently, an automated assist device has been introduced to take over chest compressions so as not to fatigue the provider, and also allows medical professionals to assess the patient quicker. The problem with these is that they take time to put on and they are not readily available as of yet.
The goal of CPR is to provide manual perfusion for the patient by restoring blood flow to the vitals organs of the body, therefore delaying the eminent death of the tissues. However, the cause of cardiac arrest is considered in whether or not to perform CPR. For example, if an otherwise healthy patient presents no pulse after a severe trauma, CPR is considered useless because it is likely that the injuries are not consistent with survival. Studies prove that the faster CPR is initiated, the better the chance of survival after defibrillation. Given this information, bystanders are encouraged to immediately begin CPR without checking for a pulse, whereas healthcare professionals are more likely to assess a pulse.
Also important to note is that CPR is not intended to restart the heart. In order to spontaneously restart the heart, an electric shock should be administered through a process called defibrillation. A patient is only a candidate for defibrillation with the following heart rhythms: ventricular fibrillation (also known as V-fib, when the ventricles of the heart are essentially quivering) or pulseless ventricular tachycardia. If a patient is asystolic (has no heart rhythm or electrical activity) defibrillation will not work. CPR does, however, have the potential to put the heart into a shockable rhythm, and most importantly it preserves the body while it is unable to circulate on its own.
While CPR is a last resort and imperative to a patient’s survival, it does lead to complications. Perhaps the most common are rib and sternal fractures, which have the potential to puncture the lungs, heart, or other internal tissues. Contusions (bruises) of the heart are also common because strong pressure is being repeatedly put on the heart. Another complication is that of the airway, including jaw fractures and tracheal injuries. Finally, internal bleeding can occur within the various chest and abdominal cavities or within organs themselves. Ultimately however, the patient’s chance of survival outweighs all of the complications from CPR.
Image Caption: CPR training. Credit: Rama/Wikipedia (CC BY-SA 2.0 FR)