Chapter 22: Basic Cardiopulmonary Resuscitation

The purpose of CPR is to temporarily provide effective oxygenation of vital organs, especially the brain and heart, through artificial circulation of oxygenated blood until the restoration of normal cardiac and respiratory activity occurs. The intended effect is to stop the degenerative processes of ischemia and anoxia caused by inadequate circulation and inadequate oxygenation.³ The time sensitivity of CPR in sudden cardiac death is emphasized in the American Heart Association “Chain of Survival” (Table 22–1).

This chapter reviews basic CPR for adults and children ≥8 years old, including the approach to an unresponsive patient; the physiology and mechanics of closed chest compression techniques; and basic airway opening procedures, including initial management of an obstructed airway. This chapter is specifically directed toward healthcare providers, although key updates for lay rescuers are noted, given the healthcare provider's role in layperson education.

Table 22–2 outlines the sequence of steps to be taken when someone is found unresponsive.

STEP 1 AND STEP 2 IN BASIC CPR

Before approaching a collapsed individual, assess the scene for risks to healthcare providers. Potential risks include the presence of hazardous materials, an unstable physical environment, or personal violence. Once the patient is reached, determine the patient's level of responsiveness to noxious stimuli. If the patient is without normal breathing, get help first before starting chest compressions. In a hospital, this may mean calling for the arrest team and requesting the arrest cart. Outside the hospital, this is likely to mean asking a bystander to activate the local EMS system. Look around to see if an automatic external defibrillator is nearby. Rapid application of defibrillation for unstable ventricular tachycardia or ventricular fibrillation is critical for patient survival.

STEP 3 IN BASIC CPR (HEALTHCARE PROVIDER ONLY)

The carotid artery is generally the most reliable and accessible location to palpate a pulse. The artery is located by placing two fingers on the trachea and then sliding them down to the groove between the trachea and the sternocleidomastoid muscle. Simultaneous palpation of both carotid arteries should not be performed because, in low-pressure states, this could obstruct cerebral blood flow and may interfere with the ability to detect a pulse. The femoral artery may be used as an alternative site to palpate a pulse. This can be found just below the inguinal ligament approximately halfway between the anterior superior iliac spine and the pubic tubercle. If no definite pulse is felt within 10 seconds, chest compression should begin.

STEP 4 IN BASIC CPR

Physiology of Closed Chest Compressions

There has been an active debate as to the exact mechanism that causes blood flow since the technique of closed chest compressions was put forth in the 1960s.^4,5 In a closed system, liquid flows when pressure gradients develop. There are three basic theories for how pressure gradients and flow are produced during closed chest cardiac massage.^6,7 The conventional theory of blood flow during compressions is called the cardiac pump theory. The pump theory postulates that direct compression of the heart between the spine and the sternum leads to increased pressure in the ventricles. This causes closure of the mitral and tricuspid valves, leading to blood flow into the aorta and the pulmonary arteries. The thoracic pump theory postulates that compressions lead to an increase in pressure throughout the thoracic cavity, leading to a pressure gradient from intrathoracic to extrathoracic arteries. The third mechanism described is the abdominal pump theory, which has both an arterial and a venous component. The arterial component postulates blood flow into the peripheral arterial system from increased arterial pressure caused by abdominal compressions that forces blood from the abdominal aorta against the closed aortic valve. The venous component leads to blood return via the inferior vena cava from abdominal pressure. However, regardless of the mechanism, conventional chest compressions generate one fourth to one third of physiologic cardiac output. Lower ratios can be expected with delays in initiating compressions. The techniques of closed chest compression are detailed in Table 22–3.

When the lack of a pulse is confirmed, begin serial rhythmic closed chest compressions. Place the victim supine on a firm surface, with the rescuer at the victim's side. Place the heel of one hand midline on the lower half of the sternum, 4 to 5 cm (~2 in.) cephalad of the xiphoid process (Figure 22–1). The heel of the hand should be parallel with the long axis of the patient's body. Then place the second hand on top of the first hand, so the hands are parallel with each other. The fingers of the two hands may be interlaced if desired, but they should not be touching the chest. Keep the arms straight and the elbows locked. The vector of the compression force should start from the rescuer's shoulders and be directed downward. Lateral compressive forces will decrease the efficiency of the compressions and increase the likelihood of complications. Depress the sternum 2-2.5 inches (5-6 cm) in an adult, at a rate of 100-120 compressions per minute. Rates lower than this are inadequate. The compression-release phases should be roughly equal in length. With a single rescuer or with two rescuers if the patient is not intubated, give two ventilations after every 30 compressions. With two rescuers assisting an intubated patient, ventilate at a rate of 8 to 10 per minute, without interrupting chest compressions. Of note, although assisting ventilation is important, not everyone is willing to perform mouth-to-mouth breathing due to concerns over infectious disease transmission. Chest compressions alone can be effective and should be provided even if rescue breathing is not being performed.^8,9

Open Chest Cardiac Compressions

Open chest cardiac massage is an alternative to standard CPR and improves blood flow in animal models. Although there are no data showing improved clinical outcomes with the use of open chest cardiac massage versus closed chest cardiac massage, this technique may be considered in a number of situations, including (1) after penetrating chest trauma; (2) the perioperative period before or after cardiothoracic surgery; (3) cardiac arrest caused by hypothermia, pulmonary embolism, pericardial tamponade, or abdominal hemorrhage; (4) cases of chest deformity in which closed chest CPR is ineffective; (5) penetrating abdominal trauma with deterioration and cardiac arrest; and (6) blunt trauma with cardiac arrest.¹⁰ However, the use of this technique requires a well-coordinated multidisciplinary team (see chapter 262, Cardiac Trauma).

STEP 5 IN BASIC CPR

Defibrillation is discussed in chapter 23, Defibrillation and Cardioversion.

Complications of CPR

Ventilations can cause insufflation of the stomach, leading to regurgitation and aspiration and possibly to gastric rupture. Closed chest compressions can lead to fractures of the sternum or the ribs, separation of the ribs from the sternum, pulmonary contusion, pneumothorax, myocardial contusion, hemorrhagic pericardial effusions, splenic laceration, or liver laceration. Proper techniques can minimize these complications but cannot totally prevent them. Late complications include pulmonary edema, GI hemorrhage, pneumonia, and recurrent cardiopulmonary arrest. Anoxic brain injury can occur in a resuscitated individual subjected to prolonged hypoxia; it is the most common cause of death in resuscitated patients.

STEP 6 IN BASIC CPR

The sixth step is to assess the upper airway of the victim. This usually requires positioning the individual supine on a flat, firm surface with the arms along the sides of the body. Unless trauma can be definitely excluded, any movement of the victim should consider the possibility of a spine injury. As the patient is placed supine, stabilize the cervical spine by maintaining the head, neck, and trunk in a straight line. If the neck is not already straight, then it should be moved as little as possible to establish the airway. If the patient cannot be placed supine, the jaw thrust maneuver (see “Jaw Thrust Maneuver” section) can be applied with the rescuer at the victim's side. Common causes of airway obstruction in an unconscious patient are occlusion of the oropharynx by the tongue and laxity of the epiglottis. With loss of muscle tone, the tongue or the epiglottis can be forced back into the oropharynx upon inspiration. This can create the effect of a one-way valve at the entrance to the trachea, leading to airway obstruction. After positioning the patient, inspect the mouth and oropharynx for secretions, foreign objects, loose (floppy) dentures, partial dentures, or broken teeth. If dentures fit properly, keep them in place if possible, as they will allow for a better seal. If secretions are present, they can be removed with the use of oropharyngeal suction if available; a visualized foreign body may be dislodged by use of a finger sweep and then manually removed. In contrast to earlier recommendations, a blind finger sweep should never be performed as there is a risk of worsening airway obstruction (see “Finger Sweep” section).

Once the oropharynx has been cleared, two basic maneuvers for opening the airway may be tried. These are the head tilt–chin lift and the jaw thrust. These maneuvers help to open the airway by mechanically displacing the mandible and the attached tongue out of the oropharynx.

Head Tilt–Chin Lift Maneuver

To perform the head tilt–chin lift maneuver, gently extend the patient's neck by placing one hand under the patient's neck and the other on the forehead and extending the head in relation to the neck. This maneuver should place the patient's head in the sniffing position, with the nose pointing up. In conjunction with the head tilt, perform the chin lift. The chin lift is done by carefully placing the hand that had been supporting the neck for the head tilt under the symphysis of the mandible, taking care not to compress the soft tissues of the submental triangle and the base of the tongue. Then lift the mandible forward and up, until the teeth barely touch. This supports the jaw and helps tilt the head back.

Jaw Thrust Maneuver

The jaw thrust is the safest method for opening the airway if there is the possibility of cervical spine injury. This maneuver helps to maintain the cervical spine in a neutral position. The rescuer, who is positioned at the head of the patient, places the hands at the sides of the victim's face, grasps the mandible at its angle, and lifts the mandible forward (Figure 22–2). This lifts the jaw and opens the airway with minimal head movement.

After opening the airway, assess respiratory effort and air movement. Look for chest expansion, and listen and feel for airflow. The simple act of opening the airway may be adequate for the return of spontaneous respirations. However, if the victim remains without adequate respiratory effort, then further intervention is required. If rescuers are reluctant to perform mouth-to-mouth ventilation and the patient is in cardiac arrest, chest compressions alone can be effective (Table 22–3).

Two breaths over 1 second each should be given with sufficient volume to cause visible chest rise. At this point, if a foreign body obstruction is noted, as indicated by a lack of chest rise or airflow on ventilation, the obstruction requires removal (Figure 22–3). Agonal respirations in an individual who has just suffered a cardiac arrest are not considered adequate for ventilation. Intermittent positive-pressure ventilation, with oxygen-enriched air if possible, should be initiated.

Ventilation Techniques

Table 22–4 outlines the recommendations for delivery of rescue breaths during cardiac arrest.² When an advanced airway (e.g., endotracheal tube, Combitube, or laryngeal mask airway) is in place during two-person CPR, ventilate at a rate of 8 to 10 breaths per minute without attempting to synchronize breaths between compressions. There should be no pause in chest compressions for delivery of ventilations.¹¹

In an adult with normal perfusion, 8 to 10 mL/kg tidal volume is required for adequate oxygenation and ventilation. However, in the setting of CPR, where cardiac output is only 25% to 33% of normal, a lower minute ventilation, and thus tidal volume, can be satisfactory. Approximately 6 to 7 mL/kg will suffice. Use an appropriately sized bag for bag-valve mask ventilation. A pediatric bag will provide inadequate tidal volumes for an adult.

There are a number of techniques for ventilating an individual, including mouth to mouth, mouth to nose, mouth to stoma, and mouth to mask. Rescue breaths with an inspiratory time of 1 second each should be given at a rate of 8 to 10 per minute, with a volume adequate to make the chest rise visibly (approximately 6 to 7 mL/kg; 500 to 600 mL in adults). Supplemental oxygen should be delivered as soon as possible. Expired air has a fraction of expired oxygen of 16% to 17%. Too large a volume or too rapid an inspiratory flow rate can cause gastric distention, which can lead to regurgitation and aspiration.

Mouth-to-Mouth Ventilation

With the airway open, gently pinch the patient's nose shut with the thumb and index finger (Figure 22–4). This prevents air escape. After taking a deep breath, place the lips around the patient's mouth, forming an airtight seal. Slowly exhale. Release the seal and allow adequate time for passive exhalation by the victim, and then repeat the procedure. Protective devices such as face shields decrease the risks to the provider of contracting an infectious disease and can be purchased from most medical equipment stores.

Mouth-to-Nose Ventilation

In some cases, as with severe maxillofacial trauma, mouth-to-nose ventilation may be effective. With the airway open, lift the patient's jaw, closing the patient's mouth. After a deep breath, place the lips around the patient's nose, forming an airtight seal. Slowly exhale.

Mouth-to-Stoma or Tracheostomy Ventilation

After laryngectomy or tracheotomy, the stoma or tracheostomy becomes the patient's airway. As with the other techniques, a seal is made around the stoma or tracheostomy tube, and the rescuer slowly exhales.

Mouth-to-Mask Ventilation

Proper and secure placement of the mask on a victim's face is important when using a mask for ventilation, either with a bag or via mouth to mask. Place the mask over the bridge of the patient's nose and around the mouth. Place the thumb on the part of the mask that is sitting on the patient's nose and place the index finger of the same hand on the part of the mask sitting on the patient's chin (Figure 22–5). The three other fingers of the same hand are then placed along the bony margin of the jaw. The mask can then be firmly sealed to the patient's face. Two hands may be used for this technique if a second rescuer is available. Ventilations are then performed through the mask. Some masks also allow for supplemental oxygenation.

Foreign Body Obstruction

It is important to recognize and be able to assist someone with an airway obstruction due to a foreign body.¹² An individual in distress from a compromised airway is likely to use the universal sign for an airway obstruction, which is for the individual to grab his or her neck with both hands. Foreign bodies can cause partial or complete obstruction. With a partial airway obstruction, air exchange may be adequate or inadequate. If the victim is able to speak, cough, and exchange air, then he or she should be encouraged to continue spontaneous efforts. Obtain assistance, such as activation of the local EMS system. Do not interfere with the patient's attempts to cough or expel the foreign body and do not perform a blind finger sweep. If air exchange becomes inadequate, as indicated by an inability to speak, increased difficulty breathing, weak and ineffective cough, worsening stridor, or cyanosis, immediate medical intervention is needed (see next section, “Obstruction-Relieving Maneuvers”). Inadequate air exchange from a severe partial or a complete airway obstruction should be managed the same way. In an unconscious person, the presence of airway obstruction may be ascertained by noting inadequate airflow and poor chest rise with efforts to ventilate.

Obstruction-Relieving Maneuvers

Maneuvers used to relieve foreign body obstructions include the Heimlich maneuver (subdiaphragmatic abdominal thrusts), chest thrusts, and the finger sweep. In a conscious individual, the obstructed airway (Heimlich) maneuver is the recommended maneuver in most adults for relieving airway obstruction due to a solid object. It is not useful for liquids. In an unconscious individual suspected of having an aspirated foreign body and in whom the foreign body is visualized, the recommended first step is the finger sweep. A blind finger sweep is no longer recommended as it may worsen airway obstruction by pushing an unseen object into an even less favorable position. Otherwise, in an unconscious patient, the recommended sequence is to perform the obstructed airway maneuver up to five times, open the mouth and perform a finger sweep if a foreign body has become visible, and then attempt to ventilate. This sequence may be repeated as often as needed until the patient recovers or additional assistance arrives.

Obstructed Airway (Heimlich) Maneuver

The Heimlich maneuver creates an artificial cough by forcefully elevating the diaphragm and forcing air from the lungs.¹³ It may be repeated multiple times. Each individual thrust should be performed aggressively, with the intention of removing the obstruction. The maneuver can be performed with the victim standing, sitting, or lying down, or it can be self-administered (Figure 22–6). To perform the maneuver with the patient standing or sitting, stand behind the patient and place the thumb side of a fist against the victim's abdomen midline just above the umbilicus and well below the xiphoid process (Figure 22–6). Grasp the fist with the other hand, and forcefully push the fist into the victim's abdomen with a quick upward thrust. Repeat until the item is dislodged or the patient becomes unconscious. For an unconscious patient, place the victim supine on a firm surface and sit astride the victim's thighs (Figure 22–7). Place the heel of the dominant hand midline just above the patient's umbilicus, and the other hand directly on top of the first. Then deliver quick upward thrusts. To self-administer thrusts, the individual can either use his or her own fist to deliver the thrusts or lean forcibly against a firm object, such as a porch rail or the back of a chair. Potential complications of the Heimlich maneuver include injury or rupture of abdominal or thoracic viscera and regurgitation of stomach contents.

Chest Thrusts

The chest thrust maneuver is used primarily if someone is morbidly obese or in the late stages of pregnancy, and the rescuer cannot reach around the patient's abdomen to perform abdominal thrusts (Figure 22–8). To perform chest thrusts with the patient standing or sitting, stand behind the patient and place the thumb side of a fist against the victim's sternum, avoiding the costal margins and the xiphoid process. Grasp the fist with the other hand, and press the fist into the victim's chest with a quick backward thrust. Repeat until the item is dislodged or the patient becomes unconscious. For an unconscious patient, place the victim supine on a firm surface and kneel close to the victim's side. Place the hands in the same position as for chest compression (i.e., the lower sternum), and deliver quick thrusts.

Finger Sweep

The finger sweep maneuver is used only in unconscious patients (Figure 22–9). Using the thumb and fingers of one hand, grasp both the tongue and the mandible and lift them. This may partially relieve the obstruction by lifting the tongue away from the back of the throat. With the other hand, insert the index finger into the back of the throat, and use a hooking action in an attempt to dislodge the foreign body to move it into the mouth for manual removal. Use care so the foreign object is not pushed deeper into the throat.

Efforts at resuscitation should be continued until the patient recovers spontaneous respirations and cardiac output, the rescuer becomes exhausted, or the patient is pronounced dead. An atraumatic individual who recovers spontaneous respirations and circulation should be placed on his or her side—the recovery position. Recovery from cardiac arrest depends on time to CPR and rhythm-specific intervention. Resuscitation and long-term outcome in normothermic patients with arrest times of 20 minutes or more are very poor.

During the initiation of resuscitation attempts, try to discover whether or not the victim has advance directives that prohibit CPR.¹⁴ Family members may wish to be present during resuscitation attempts,¹⁴ and support from social services and clergy should be sought early (see chapter 27, Ethical Issues of Resuscitation).