I would like to note that this article is written perhaps too simply. On the other hand, I think that simplicity (and the omission of certain information) is quite desired in this issue. The information about cardiopulmonary resuscitation (CPR) should be written very comprehensibly to make it understandable and useful.
Cardiopulmonary resuscitation is a set of procedures aimed to ensure restoration of vital functions of the affected person. We distinguish basic resuscitation (usually performed by laymen without any equipment with possible exception of external defibrillator) and advanced resuscitation (performed by trained staff with equipment).
Basic cardiopulmonary resuscitation
Cardiopulmonary resuscitation of an adult usually starts with finding an unconscious person and quick check of the absence of basic life functions. The laymen should evaluate at least the absence of breath, paramedics and physicians should try to confirm absence of pulse. Determining the absence of breathing may be associated with a rapid look into the one's oral cavity and exclusion of clearly visible obstacles.
After determining the absence of vital functions in an adult, the rescuer should first call for a professional help (rule of "First call"). In case of a single rescuer, he should call for help and then begin the own resuscitation. When there are more rescuers, one calls, while the others perform the CPR. It may seem inhuman to phone, when there is a dying person nearby, but it has its reasons:
a) In adults, sudden failure of the cardiorespiratory system with unconsciousness is usually caused by a heart disorder, typically by a malignant arrhythmia such as the ventricular fibrillation. It is unlikely that a layman will be able to solve this problem and the only possibility of salvation is the arrival of trained professional rescuers with proper equipment. A layman can help to keep the person alive, but solving the underlying cause is the work of professional rescuers.
b) The emergency medical dispatcher not only sends the rescue team to the desired location, but he can also advise non-professional rescuers how to proceed in cardiopulmonary resuscitation.
Basic lay resuscitation begins with ensuring free airways. It is crucial to bend the head backward (to prevent obstruction of the airways by the tongue), which is followed by mouth-to-mouth rescue breathing and heart massage. The frequency is about 30 chest compressions to 2 inhalations and this process should be repeated about 3 times per minute. Since it is difficult for the layman to keep a good rhythm, it is unofficially recommended to start massaging on the rhythm of Christmas carol "Jingle bells, jingle bells".
When there are more rescuers, they should rotate after a minute. The correct technique can not be fully described by words and people should train it in various first-aid courses. I would just like to emphasize the importance of stretched non-bent upper limbs and sufficient force to compress the chest. The rescuer should not be afraid of sound of cracking ribs that may occur when resuscitating an elderly person.
In the event that there is an external defibrillator, it must be activated as quickly as possible with connection of electrodes to the unconscious person. The device evaluates the presence and type of cardiac rhythm and it either an electrical discharge to restore the normal heart rhythm, or advises on further steps.
The CPR should be carried out until the arrival of emergency service, or until utter exhaustion of the non-professional rescuers.
Note 1: In case of clear evidence that the coma occurred due to inhaled foreign body, it is recommended to perform the so-called Heimlich maneuver.
Note 2: In case you do not want to perform mouth-to-mouth rescue breathing (e.g. in a homeless person with bleeding from the mouth, etc.) it is allowed to carry out only the heart massage alone.
Note 3: In children, the basic resuscitation should begin with mouth-to-mouth rescue breathing and heart massage. When this has no effect in 2-3 minutes, it is recommended to call the emergency. This is due to the fact that acute cardiorespiratory failure in children is usually caused by respiratory cause and there is a chance that clearing the airways (that can be performed by a layman) may have an effect.
Advanced cardiopulmonary resuscitation
Advanced CPR is performed by trained medical personnel with professional equipment. and greater than lay rescuers. In addition to classic CPR (i.e. mouth-to-mouth rescue breathing and heart massage), the advanced CPR includes further processes.
Securing the airways
Patient's airways may be secured by intubation, i.e. introduction of a special tube equipped by a fixation balloon into the airways. Simpler is the introduction of laryngeal mask or other devices. The actual respiration is performed by using a special CPR bag valve mask attached to the intubation tube.
Ensuring venous access
When possible, at least one of the peripheral veins should be secured by an intravenous cannula. This cannula can serve for application of drugs used during resuscitation (see below).
Using the defibrillator
Defibrillator is a fundamental advantage of advanced CPR. It allows (after attaching its electrodes to the patient's chest) to visually evaluate the heart rhythm, which is necessary for further resuscitation.
If the device shows the rescuers an arrhythmia such as ventricular fibrillation, the primary method is defibrillation. Defibrillation means sending an electrical impulse to the heart of the patient, which should ensure the return of normal heart rhythm. This is actually a procedure analogous to the action of external defibrillator, but in this case, the rescuers are the ones, who decide about the defibrillation. The defibrillation should be performed right after the patient fell unconscious, otherwise it should be preceded by at least 2 minutes lasting classic resuscitation (rescue breathing, heart massage), because oxygenated heart responds better to the electrical current.
Unsuccessful defibrillation of ventricular fibrillation should be followed by 2 minutes of classic CPR and subsequent repeating of the defibrillation. After the third unsuccessful defibrillation, it is advisable to begin with the pharmacotherapy. The scheme in this case is as follows: 2 minutes classical resuscitation - epinephrine - defibrillation - repeating the cycle until recovery of the normal heart rate, or death of the patient.
When the screen of the defibrillator shows zero cardiac activity, (straight horizontal line well-known from the movies), or so-called pulseless electrical activity, the rescuers should perform just the classic CPR with administration of intravenous drugs. In this case, the defibrillation has no sense, because there is nothing to defibrillate. A situation where a doctor in a movie reacts to the straight line on the monitor by administration of electric discharge, it is completely fictional.
The medication is administered intravenously. The most commonly used drug is epinephrine, which is administered in dose of 1 mg every 3 to 5 minutes until the end of resuscitation. The repeated administration of epinephrine is performed in case of no cardiac activity combined with classic resuscitation (breathing, massage). Epinephrine, however, also serves in case of ventricular fibrillation after 3 unsuccessful defibrillations. Amiodarone is an anti-arrhythmic drug administered to counteract heart arrhythmias. It is served at a dose of 300mg in a solution of 20ml of 5% glucose in case, that even three defibrillations did not restore the normal heart action. During resuscitation, atropine may be also administered when there is an extremely slow heart rate (bradycardia). Complementary and less commonly used drug is bicarbonate (NaHCO3). Its 8.5% solution is administered between 50 to 100 ml. Bicarbonate helps to adjust the acidity of the body, which occurs when the breathing has stopped.