Guidelines for cardiopulmonary resuscitation: Basic and advanced cardiovascular life support-I

by Philip J Podrid, MD

UpToDate performs a continuous review of over 270 journals and other resources. Updates are added as important new information is published. The literature review for version 10.3 is current through August 2004; this topic was last changed on August 7, 2004.

The outcome of an emergency situation and survival of the patient

are critically dependent upon the first few minutes of care; the actions that should occur promptly during this time define basic life support and include [1]:

• Prompt recognition and action for myocardial infarction and stroke to prevent respiratory and cardiac arrest

• Establishment and maintenance of breathing for victims of respiratory arrest

• Attempted cardioversion/defibrillation for patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) with an automated external defibrillator (AED) (show algorithm 1) [2,3]. (See "Basic principles and technique of cardioversion and defibrillation", section on Automatic external cardioverter defibrillator).

With the growing availability of AEDs in the community and workplace, basic life support now includes early access to emergency medical services (EMS) system, early cardiopulmonary resuscitation (CPR), and early defibrillation; this is then followed by advanced cardiovascular life support (ACLS) [4,5].

Early access to EMS requires prompt recognition of those emergencies that require time-critical basic life support intervention, most importantly defibrillation. Since most adults with sudden, nontraumatic cardiac arrest have a ventricular tachyarrhythmia, primarily VF, a telephone call to the EMS system should immediately follow recognition of an emergency ("phone first").

Early CPR is the best treatment for cardiac arrest until there is an EMS response, ie, the arrival of ACLS care and an AED [4,5]. Early CPR may prevent VF from deteriorating into asystole, may increase the chance for successful defibrillation, contributes to the preservation of heart and brain function, and significantly improves survival [6,7]. (See "Acute therapy and outcome of sudden cardiac death").

Early defibrillation is the single most important determinant for survival of adult victims of a cardiac arrest [1,3]. Survival from a cardiac arrest caused by VF declines by 7 to 10 percent for each minute without defibrillation; after more than 12 minutes, the survival rate is only 2 to 5 percent [8-13]. Because of the importance of time, the availability of AEDs in the community (public access defibrillation) to be used by trained lay persons is a major advance in CPR. Resuscitation rates with the the AED are as high as 49 percent, which are nearly twice those achieved by successful EMS programs (show algorithm 1) [8,14-18].

Guidelines for basic and advanced cardiovascular life support will be presented here. They are based upon the guidelines published in August 2000 by American Heart Association in collaboration with the International Liaison Committee on Resuscitation [19,20]. Controversies in CPR, such as active compression-decompression CPR, high dose epinephrine, and the need for sodium bicarbonate are also discussed separately. (See "Controversies in cardiopulmonary resuscitation").

SEQUENCE OF BASIC LIFE SUPPORT – The basic life support sequence discussed below applied to victims who are at least eight years of age and includes assessment and support/intervention [19]. No procedures of CPR should be performed until the need has been established by appropriate assessment of initial response, followed by ongoing assessment of the response to CPR (show algorithm 2).

Assess responsiveness – After arriving at the side of the collapsed victim, there must be a rapid assessment for any injury and for responsiveness. If neck or head trauma is seen or suspected, the victim should be moved only if absolutely necessary.

Activate the EMS system – The EMS system is activated by calling the appropriate local emergency telephone number. Information supplied to the operator includes location of the emergency, telephone number from which the call is being made, the nature of the emergency, the number of persons requiring help, condition of the victim, and what aid is being given; other information may be requested by the operator [21].

Airway – When the victim is unresponsive, it is important to establish if there is spontaneous respiration; to assess breathing, the victim should be supine with an open airway. In the unresponsive victim, muscle tone is decreased and the tongue and epiglottis may obstruct the pharynx [22,23]. The tongue is the most common cause for airway obstruction; moving the lower jaw forward will lift the tongue away from the back of the neck and open the airway. Any visible foreign material or vomitus must be removed from the mouth and liquids or semi-liquids wiped out.

Head tilt-chin lift maneuver – If there is no evidence of head or neck trauma, the head tilt-chin lift maneuver is used to open the airway. The rescuer can be beside the victim or behind the victim's head. The palm of one hand is placed on the victim's forehead and firm backward pressure is applied; the fingers (not the thumb) of the other hand are placed on the bony part of the lower jaw near the chin. The lower jaw is moved upward, bringing the chin forward and teeth almost to occlusion; this maneuver supports the jaw and helps tilt the head back. The victim's mouth is opened to facilitate spontaneous breathing and to prepare for mouth-to-mouth breathing. Any dentures should be removed if they cannot be kept in place.

Jaw-thrust maneuver – The jaw-thrust maneuver without tilt is an alternative for opening the airway; it is the safest initial approach to open the airway if neck injury is suspected since it can be performed without extending the neck. With the rescuer behind the victim, one hand is placed on each side of the victim's head, resting the elbows on the surface on which the victim is lying. The angles of the lower jaw are grasped and lifted with both hands. The lower lip can be retracted with the thumb if necessary to open the mouth. If mouth-to-mouth breathing is necessary while maintaining the jaw thrust, the rescuer can close the victim's nostrils by pressing his cheeks tightly against them.

Breathing – Once the airway is opened, as assessment for breathing should be performed promptly; the rescuer places his or her ear near the victims mouth and nose while maintaining an open airway. The victim's chest should be observed:

• Look for the chest rising and falling

• Listen for air escaping during exhalation

• Feel for the flow of air

The absence of the chest rising and falling and no air being exhaled indicates the absence of respirations. However, even when these signs are present, respiration may be only weak and inadequate; on occasion respiration may be only a reflex, gasping effort or agonal. Absent or inadequate respiration requires rescue breathing while, if respiration is present, the victim should be positioned properly to maintain a patent airway.

Management of an unconscious victim who is breathing – The victim who is unresponsive, but is breathing and has adequate circulation, should be positioned on his/her side (lateral or modified lateral position) to prevent airway obstruction by the tongue or mucus and to allow adequate drainage of fluid from the mouth. After approximately 30 minutes, the victim should be turned to the opposite side. Several principles should be kept in mind when positioning the victim [24]:

• The victim should be in as near a true lateral position as possible, with the head dependent to allow free drainage

• The position should be stable

• Any pressure on the chest that could impair breathing should be avoided

• The victim should be easily and safely turned onto the side and returned to the back, if necessary

• The position should permit continued observation and access to the airway

• The position should not result in injury to the victim; it is important to monitor the lowermost arm for evidence of impaired blood flow [25,26]

If the victim remains in the recovery position for more than 30 minutes, he/she should be turned to the opposite side; it is important to avoid injury when turning the victim.

Management of the victim with absent respiration – When respiration is absent, rescue breathing must be provided; this requires adequate inflation of the victim's lungs with each breath.

• Mouth-to-mouth breathing – Mouth-to-mouth breathing is a quick and efficient way to provide adequate oxygen and ventilation to the victim. The victim's airway is held open by resting the palm of one hand on the victims forehead.; the victim's nose is pinched with the thumb and index finger in order to prevent air from escaping. After the rescuer takes a deep breath, he makes an airtight seal with his/her mouth over the victim's mouth and gives slow breaths, delivering each breath over two seconds, making certain that the victim's chest rises with each breath and feeling air escape during exhalation. After initially delivering two to five breaths, approximately 10 to 12 breaths are delivered each minute, or one every four to five seconds.

Gastric inflation often develops during mouth-to-mouth breathing; this risk can be reduced by maintaining an open airway and delivering slow breaths (allowing two seconds between breaths) at the lowest volume that will still make the chest visibly rise with each breath (approximately 700 to 1000 mL) [27,28]. If gastric distension occurs, recheck and open airway and look for the rise an fall of the chest. (see below under complications of rescue breathing).

If initial attempts to ventilate the victim are unsuccessful, the victim's head should be repositioned and rescue breathing repeated.

On occasion mouth-to-mouth breathing is performed using a barrier device. There are two types of barrier devices: a mouth-to-mask has a one-way valve so that the victim's air does not enter the rescuers mouth; and a face shield, which does not have an exhalation valve and the victim's expired air escapes between the shield and the victim's face.

• Mouth-to-nose breathing – The mouth-to-nose method of ventilation is recommended when mouth-to-mouth ventilation is impossible because the mouth cannot be opened (trismus), the mouth is seriously injured, or a tight mouth-to-mouth seal cannot be achieved. The victim's head is tilted back with one hand on the forehead; the other hand is used to lift the victim's mandible (as in the head tilt-chin lift maneuver) and the victim's mouth is closed; the rescuer takes a deep breath, seals his/her lips around the victim's nose. and exhales into the nose. The lips are then removed from the nose, allowing for exhalation; if partial nasal obstruction is present, it may be necessary to open the victim's mouth intermittently to allow for free exhalation.

• Bag-to-mouth breathing – Bag-mask devices are often used in the prehospital setting by emergency medical personnel. These devices consist of a self-inflating bag, with a volume of approximately 1600 mL and a nonrebreathing valve attached to a face mask. However, because of difficultly in obtaining a leak-proof seal while both squeezing the bag and maintaining an open airway, these devices are most effective when two trained and experienced rescuers work together, one sealing the mask to the face and the other squeezing the bag over two seconds. When there is only one rescuer, he/she is positioned at the top of the victim's head and the head is tilted back and the mask applied to the victim's face with one hand, using the bridge of the nose as a guide for correct position. The third, fourth, and fifth fingers of the hand are placed along the bony portion of the mandible and the thumb and index finger of the same hand are placed on the mask. The bag is squeezed with the other hand, observing the chest for adequate ventilation; each breath is delivered over two seconds.

Complications of rescue breathing – The most common complication of rescue breathing is gastric inflation resulting from excessive ventilation volume and rapid flow rates [28-30]. The risk is also increased because the lower esophageal sphincter relaxes during a cardiac arrest [31]. Marked inflation of the stomach may promote regurgitation, aspiration, and pneumonia [31-35]; the increased intragastric pressure also reduces lung volumes (by elevating the diaphragm) and respiratory system compliance [27,36-39].

If gastric distension occurs, slow rescue breathing is continued. There should not be an attempt to expel the stomach contents since this increases the potential for regurgitation. If regurgitation occurs, the victim's entire body is turned to the side, the mouth is wiped out, the body returned to the supine position, and CPR continued.

Circulation – Although palpation of the carotid pulse has been the gold standard for determining if the heart is beating, this is not reliable when used by lay persons [40-42]. As a result, the lay person should not rely on the carotid pulse check to determine the need for chest compression or use of an AED. In contrast, the healthcare professional should continue to use the carotid pulse check as one of several signs of circulation; however, many will be unable to identify a carotid pulse within five seconds [42-44].

Assessment of signs of circulation – The lay person should assess for signs of circulation following the delivery of initial rescue breaths; this includes evaluation for normal breathing, coughing, or movement in response to rescue breathing. The following sequence should be performed:

• Provide initial rescue breathing to the unresponsive, nonbreathing victim.

• Look for signs of circulation. With the ear near the victim's mouth look, listen, and feel for normal breathing; quickly scan the victim for any signs of movement.

• If the victim is not breathing normally, coughing, or moving, immediately begin chest compression.

Healthcare providers should perform a pulse check in conjunction with an assessment for signs of circulation. For victims over one year of age, the carotid artery (located in the groove between the trachea and muscles at the side of the neck) is the preferred artery to palpate. If it is uncertain if circulation is present, chest compression should be initiated immediately.

Chest compressions – Chest compressions for CPR are serial, rhythmic applications of pressure over the lower half of the sternum; these compressions produce blood flow by increasing intrathoracic pressure and directly compressing the heart. A compression rate, ie, the speed of compressions not the actual number delivered in one minute, of 100 per minute is recommended (class IIb) [45-47]. A ratio of 15 compressions to 2 ventilations is recommended for one or two rescuers until the airway is secured [48,49].

Proper hand placement is established by identifying the lower half of the sternum:

• The rescuers fingers are placed on the lower margins of the victims rib cage on the nearest side.

• The fingers are slid up the rib cage to the notch where the ribs meet the lower sternum in the center of the lower part of the chest.

• The heel of one hand is placed on the lower half of the sternum (not the lowest portion of the sternum, which is the xiphoid process) and the other hand on top of the first, so that the hands are parallel. The long axis of the heel of the hand is placed on the long axis of the sternum; this keeps the main force of compression on the sternum and reduces the chance of rib fracture.

• The fingers should be either extended or interlaced, but kept off the chest.

Alternatively, the rescuer can achieve correct hand position by placing the heel of the one hand in the center of the chest, between the nipples.

Effective chest compression can produce arterial blood pressure peaks of 60 to 80 mmHg, with a mean blood pressure of 40 mmHg; cardiac output resulting from chest compression is probably one-fourth to one-third of normal, but decreases during the course of prolonged CPR [50]. For chest compression to be effective, attention to the following is required:

• Elbows locked in position, with the arms straightened and shoulders directly over the hands, so that the thrust of each compression is straight down on the sternum.

• In the normal-sized adult, the sternum is compressed approximately 2 inches (4 to 5 cm); however, optimal sternal compression is best gauged by identifying the force that generates a palpable carotid or femoral pulse [51].

• After each compression, the pressure must be completely released, allowing the chest to return to its normal position; the rescuers hands, however, must remain in contact with the victim's sternum to insure proper hand position for subsequent compressions.

• The most effective cerebral and coronary perfusion is achieved when 50 percent of the cycle is devoted to chest compression phase and 50 percent to chest relaxation [52,53].

There have been a number of other techniques used in order to improve blood flow during CPR, such as active compression-decompression CPR; however, these methods have not been shown to improve the outcome of CPR. (See "Controversies in cardiopulmonary resuscitation").

Rescue breathing and chest compression should be combined for effective CPR. However, the need for and safety of mouth-to-mouth breathing is an important concern regarding the complexity of CPR and the inexperience of bystanders; in addition there are concerns about the transmission of infectious disease, although the actual risk is very small [54]. Nevertheless, fears regarding disease transmission, especially HIV, are common and result in reluctance to perform mouth-to-mouth ventilation [55-58]. One study evaluated whether chest compression alone was as effective as chest compression and mouth-to-mouth ventilation; the outcome was the same with the two methods [59]. Thus, if a person is unwilling or unable to perform mouth-to-mouth ventilation for an adult victim, chest compression only CPR should be provided rather than no attempt at CPR being made (class IIa recommendation). (See "Controversies in cardiopulmonary resuscitation").

Complication of chest compression – Although the risks of chest compression can be minimized by proper hand position, complications can occur even with properly performed chest compression. These include rib fractures, fracture of the sternum, separation of the ribs from the sternum, pneumothorax, hemothorax, lung contusions, laceration of the liver and spleen, and fat embolism.

Defibrillation – Most adult victims of sudden, witnessed, nontraumatic cardiac arrest are in ventricular fibrillation. The single most important determinant of survival is the time from collapse to defibrillation; survival from a ventricular fibrillation cardiac arrest declines by 7 to 10 percent for each minute without defibrillation. Early defibrillation in the community is defined as a shock delivered within five minutes of EMS call receipt. Early defibrillation must also be provided in hospitals and medical facilities; in these areas healthcare providers should be able to deliver a shock within three minutes of an arrest (class I recommendation).

The discussion of advanced cardiac life support is continued separately. (See "Guidelines for cardiopulmonary resuscitation: Basic and advanced cardiovascular life support-II").

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