Determining Unresponsiveness

BLS begins when a victim is found unresponsive and not moving. Because many hospitalized patients exhibit decreased levels of consciousness, health care personnel should avoid needless intervention by careful assessment of the patient.

When a person encounters a collapsed victim outside the hospital setting who appears to be unconscious, he or she should first look for any obvious head or neck injuries. If such injuries are apparent, great care should be taken in subsequent manipulation of the neck and in any effort to move the individual.

Whatever the location, the victim’s level of consciousness should be assessed quickly by checking for signs of life (e.g., movement and normal breathing). The rescuer should call for help and activate the emergency medical services (EMS) system if the patient is not moving or breathing or only gasping. Outside the hospital, someone may need to call 911 or the emergency number for the local EMS system. Within the hospital, specific protocols exist for “calling a code.” All RTs must be familiar with the protocols of their institution for handling these emergency situations.

For ease of training, the lay rescuer should be taught to assume that a cardiac arrest is present if the unresponsive victim is not breathing or gasping. Health care workers may also take too long for a pulse check and have difficulty determining if a pulse is present. For this reason, rescuers should proceed with chest compressions if no pulse is found within 10 seconds.

Pulselessness is evaluated by palpating a major artery. In adults and children older than 1 year, the carotid artery in the neck or femoral artery should be palpated. To locate the carotid artery, the rescuer should maintain the head-tilt with one hand while sliding the fingers of the other hand into the groove created by the trachea and the large neck muscles (Figure 34-1). The carotid artery area must be palpated gently to avoid compressing the artery or pushing on the carotid sinus. Because the pulse may be slow, weak, or irregular, the artery may need to be assessed for approximately 10 seconds for the presence or absence of a pulse to be confirmed.

For infants, the brachial artery is preferred for assessing pulselessness. To palpate the brachial artery, the rescuer must grasp the infant’s arm with his or her thumb outward, slide his or her fingers down toward the antecubital fossa, and press gently to feel for a pulse. The femoral artery also can be palpated, which may be done for an adult, a child, or an infant.

In hospital critical care settings, bedside monitoring equipment may provide supporting or confirming information regarding the respiratory or circulatory status of a patient. However, information obtained from these devices should never be a substitute for careful clinical assessment.

If the patient has a pulse but is not breathing, ventilation must be started immediately, at the appropriate rate of 8 to 10 breaths/min (every 6 to 8 seconds). If no pulse is palpable, external chest compressions must be interposed with ventilatory support (see Table 34-1).

Providing Chest Compressions

Adequate circulation can be restored in a pulseless victim using external chest compressions. The rescuer manually compresses the lower half of the sternum (for an adult patient) at a rate of 100 compressions/min. The duty cycle for downstroke and upstroke (release) is 600 msec with a 1 : 1 downstroke-to-upstroke ratio. It is very important to have a complete upstroke so as not to increase intrathoracic pressure during the diastolic phase. The best way to ensure that the upstroke is complete is for the rescuer to take his or her hand slightly off the chest between compressions.⁵ Cardiac output produced by external chest compressions is approximately one-fourth of normal cardiac output, with arterial systolic blood pressures between 60 mm Hg and 80 mm Hg. Blood flow during chest compression probably results from changes in the intrathoracic pressure.

Adults

The procedure for providing chest compressions to adults is as follows (Figures 34-2 and 34-3):

1. Place the victim in a supine position on a firm surface, such as the ground or the floor, because chest compressions are more effective when the victim is on a firm surface. When victims are in bed or on a stretcher, place a board or tray under them. A cardiac arrest board is ideal, but a removable bed piece or food tray may have to be used.

2. Expose the patient’s chest to identify landmarks for correct hand position. If the victim is fully clothed, quickly remove or cut off any clothing or underwear.

3. Choose a position close to the patient’s upper chest so that the weight of your upper body can be used for compression. If the patient is on a bed or stretcher, stand next to it with the patient close to that side. If the bed is high or you are short, you may need to lower the bed, stand on a stool or chair, or kneel on the bed next to the victim. If the patient is on the ground, kneel at his or her side.

4. Identify the lower half of the victim’s sternum, in the center of the chest between the nipples, and place the heel of your hand on the sternum with your other hand on top, and lock your elbows.⁶

5. Perform compression with the weight of your body exerting force on your outstretched arms, elbows held straight. Your shoulders should be positioned above the patient so that the thrust of each compression goes straight down onto the sternum, using your upper body weight and the hip joints as a fulcrum (see Figure 34-2). It is acceptable to let your hands leave the victim’s chest ever so slightly to ensure a complete upstroke (see Figure 34-3).

6. Compress the sternum 2 in (5 cm) at a rate of 100 compressions/min. The compression phase of the cycle should be equal in duration to the upstroke phase.

7. If CPR must be interrupted for transportation or advanced life support measures, resume chest compressions as quickly as possible. Compressions should not cease for more than 5 seconds (30 seconds if the victim is being intubated).

Children

Children who have reached puberty should receive chest compressions as outlined for adults. The procedure for younger children (1 year old to puberty) is as follows:

1. Place the victim in the supine position on a firm surface. Small children may require additional support under the upper body; this is particularly true when chest compressions are given with mouth-to-mouth ventilation because extension of the neck raises the shoulders. The head should be no higher than the body.

2. As with an adult, identify the lower half of the sternum. Because the liver and spleen of younger children lie higher in the abdominal cavity, take special care to ensure proper positioning as described previously. However, use only one hand to compress. Use the other hand to maintain head position and maintain an airway.

3. Compress the chest approximately 2 in (5 cm) at a rate of 100 compressions/min. Generally, the heel of one hand is sufficient to achieve compression. As with adults, compression and relaxation times should be equal in length and delivered smoothly.

Infants

The procedure for infants (≤1 year of age) is as follows (Figure 34-4):

1. Use the lower half of the sternum for compression in an infant. Proper placement is determined by imagining a line across the chest connecting the nipples. Place your index finger along this line on the sternum. Then place your middle and ring fingers next to the index finger. Raise your index finger and perform compressions with the middle and ring fingers. Use the other hand to maintain the infant’s head position and airway.

2. Compress the sternum approximately 1.5 in (4 cm) at a rate of at least 100 compressions/min. Compression and upstroke phases should be equal in length and delivered smoothly. Your fingers should remain on the chest at all times.

Neonates

Chest compressions are indicated if the neonate’s heart rate decreases to less than 60 beats/min despite adequate ventilation with 100% oxygen (O₂) for 30 seconds. Before starting chest compressions, the rescuer should ensure that the neonate is being ventilated optimally.⁷ Neonatal chest compressions are delivered on the lower third of the sternum to a depth of approximately one-third of the anteroposterior diameter of the chest to achieve an approximate rate of 100 compressions/min.^7–10 Two methods have been described. The first method uses a “wraparound” technique (Figure 34-5). To use this method, the rescuer encircles the neonate’s chest with both hands and compresses the sternum with two thumbs, using the other fingers of both hands to support the neonate’s back. The rescuer should position the thumbs just below the victim’s intermammary line, taking care not to compress the xiphoid process. Compression should be performed smoothly, with downstroke and upstroke times approximately equal. Delivering a slightly shorter compression than relaxation phase may allow for more blood flow in a very young infant.¹¹ In all infants, the chest should be allowed to expand fully after a compression. After every third compression, the neonate should receive a breath of 100% O₂, coordinated with compressions to avoid simultaneous delivery. The second method, the two-finger technique (see Figure 34-4), may have advantages when access to the umbilicus is required.

Restoring the Airway

After calling for help and activating the EMS system, the rescuer should try to open the victim’s airway. First, the victim should be quickly inspected for any neck or facial trauma. If spinal cord trauma is suspected, the neck must be carefully positioned in a neutral in-line position, and procedures requiring hyperextension must be modified. In addition, when a victim is found lying on his or her side or stomach, he or she should be moved to a supine position before airway procedures are begun. Manual in-line spinal motion restriction should be employed when moving the patient. The rescuer must ensure that the victim is positioned on a hard, flat surface.

The most common cause of airway obstruction is loss of muscle tone, which causes the tongue to fall back into the pharynx, blocking airflow. Movement of the lower jaw and extension of the neck pulls the tongue from the posterior pharyngeal wall and opens the airway. One of two procedures can be used: (1) The head-tilt/chin-lift method is the primary procedure recommended for a layperson when spinal trauma is not suspected (Figures 34-6 and 34-7). (2) The jaw thrust is used mainly by trained clinicians when spinal neck injuries are suspected and is no longer recommended by the AHA for lay rescuers (see Figure 34-7). Health care providers should use a head-tilt/chin-lift procedure if the jaw thrust maneuver does not open the airway.⁴ One of these maneuvers usually can open the airway and may be the only lifesaving measure required. Research supports using manual in-line spinal immobilization rather than motion restriction devices that may complicate airway management during CPR.⁸ Cervical collars can cause increased intracranial pressure in a patient with a head injury.⁹ After the airway is cleared and opened, the rescuer must immediately assess the victim’s ventilation.

Restoring Ventilation

Before attempting to provide artificial ventilation, the rescuer should assess for the presence of breathing. To determine breathlessness, the rescuer places his or her ear over the victim’s mouth and nose while simultaneously observing for spontaneous chest movement (Figure 34-8). Breathlessness exists if no chest movement or breath sounds are present or only gasping is present. This evaluation should take no longer than 3 to 5 seconds to complete.

Providing Artificial Ventilation

During respiratory arrest, the victim must be provided with O₂ within 4 to 6 minutes, or biologic death follows. The rescuer can restore O₂ supply to the victim’s lungs by exhaling into the victim’s mouth, nose, or tracheal stoma. These procedures can be used for any victim, with appropriate modification for the patient’s age.

Mouth-to-Mouth Ventilation

Adequate oxygenation can be restored through mouth-to-mouth ventilation. To do this, the rescuer must take a slightly deeper than normal breath (700 to 1000 ml) and exhale directly into the victim’s mouth over 1 second to produce visible chest rise. Exhaled air provides approximately 16% O₂, which is sufficient to achieve an arterial oxygen tension (PaO₂) of 50 to 60 mm Hg. A tidal volume (V_T) between 700 ml and 1000 ml is ideal for most adults. A V_T of 500 ml should be delivered when chest compressions are being administered. Children require proportionally smaller volumes.

During resuscitation of a victim of cardiac arrest, two breaths should be given over a period of 1 second each. Excessive volumes (>500 ml) or an inspiratory rate that is too fast (>8 to 10 breaths/min) must be avoided because this can push air into the stomach causing gastric inflation and increase intrathoracic pressure. Increased intrathoracic pressure can decrease coronary and cerebral perfusion. Visible chest rise should be used to gauge the V_T needed in children and adults.

Adults

The procedure for adults is as follows (Figure 34-9):

1. Place the victim on his or her back on a hard, flat surface.

2. Kneel at the patient’s side, and open and clear the airway as previously described. Pinch the victim’s nose with your thumb and index finger close to the nares to prevent air from escaping during ventilation.

3. Take a slightly deeper than normal breath and deliver 500 ml over 1 second, while making a seal over the victim’s mouth. A good seal over the patient’s mouth is essential. If a good seal cannot be obtained using this method, attempt mouth-to-nose ventilation.

4. Remove your mouth from the patient’s mouth, and allow the victim to exhale passively. Provide a second breath after exhalation is complete.

5. After successfully delivering two breaths, immediately assess the circulatory status.

6. Should the initial attempt to ventilate fail, reposition the victim’s head and repeat the effort. If a second attempt at ventilation fails, the victim may have foreign body airway obstruction (FBAO), and the procedures for handling such situations described elsewhere in this chapter should be followed.

7. Assuming mouth-to-mouth ventilation is successful and the patient remains apneic, continue the effort at a rate of one breath every 6 to 7 seconds to maintain the minimal adult rate of 8 to 10 breaths/min.

Infants and Children

Airway opening maneuvers for children and infants are similar to maneuvers for adults, with several key differences. Anatomic differences in the infant’s airway make it especially susceptible to occlusion by the tongue. The infant’s head should be extended only slightly, or it should be tilted back gently into a neutral position when the head-tilt/chin-lift maneuver is used. The procedure for children and infants is as follows (Figure 34-10):

1. If the patient is an infant (<1 year old), create an airtight seal by placing your mouth over the infant’s nose and mouth (see Figure 34-10).

2. If the patient is a child between 1 year old and puberty, ventilate the victim’s lungs using the same technique as would be used for an adult (see Figure 34-9).

3. Provide an initial breath (over 1 second) sufficient to cause a visible rise in the chest. In infants, small puffs of air from the rescuer’s cheeks are usually sufficient to achieve adequate ventilation.

4. Remove your mouth, and allow the victim to exhale passively. Provide a second breath after this deflation pause.

5. After successfully delivering two breaths, immediately assess the pulse (<10 seconds).

6. If the initial attempt to ventilate fails, reposition the victim’s head and repeat the effort. A child’s head may need to be moved through a wide range of positions to secure an open airway. Hyperextension of a child’s neck can cause obstruction and should be avoided. If a second attempt at ventilation fails, the victim may have FBAO, and the appropriate procedures outlined elsewhere in this chapter should be followed.

7. Assuming mouth-to-mouth ventilation is successful and the child remains apneic, continue to provide one breath every 3 to 5 seconds to maintain a rate of 12 to 20 breaths/min.

Mouth-to-Nose Ventilation

Mouth-to-mouth ventilation cannot be performed in some situations; these include trismus (involuntary contraction of the jaw muscles, also known as lockjaw) and traumatic jaw or mouth injury. Also, sometimes it is difficult to maintain a tight seal with the lips using the mouth-to-mouth method. In these situations, mouth-to-nose ventilation should be used. The procedure is as follows (Figure 34-11):

1. Place the victim on his or her back.

2. Use the head-tilt/chin-lift maneuver to establish the airway, taking care to close the mouth completely.

3. Inhale slightly deeper than normal and exhale into the patient’s nose. Greater force may need to be applied than would be used with mouth-to-mouth ventilation because the nasal passageways are smaller.

4. Remove your mouth from the victim’s nose to allow the patient to exhale passively. If the patient does not exhale through the nose (because of nasopharyngeal obstruction from the soft palate), open the victim’s mouth or separate his or her lips to facilitate exhalation.

5. After successfully delivering two slow breaths, immediately assess the circulatory status.

6. If the victim remains apneic, maintain ventilation at the rate appropriate for his or her age.

Mouth-to-Stoma Ventilation

Patients with tracheostomies or laryngectomies can be ventilated directly through the stoma or tube. These patients can be identified by an obvious stoma or a tracheostomy or laryngectomy tube in place. Some patients wear a medical alert tag or bracelet indicating that a stoma is present. The procedure for mouth-to-stoma ventilation is as follows:

1. Place the victim on his or her back with the neck in vertical alignment. Usually, the neck does not need to be extended and the nose or mouth does not need to be sealed because oropharyngeal structures are bypassed by the stoma.

2. Ensure that the stoma is clear of any obstructing matter and breathe directly into the stoma (or tube). If the victim has a cuffed tracheostomy tube in place, inflate the cuff to prevent air from escaping around the tube. If the tube is uncuffed, the mouth and nose may need to be sealed off with your hand or a tight-fitting face mask, using a pediatric face mask to create an adequate peristomal seal for bag-mask ventilation.

3. After delivering two breaths, immediately assess the circulatory status.

4. If the victim remains apneic, maintain ventilation at the rate appropriate for his or her age.

One-Rescuer versus Two-Rescuer Adult Cardiopulmonary Resuscitation

Outside the hospital, one-rescuer CPR is common. In such cases, the rescuer must assess the victim, call for help, and begin CPR without assistance from others. The rescuer must remain calm and remember the steps of one-rescuer CPR. The technique for performing chest compressions, opening the airway, and giving mouth-to-mouth breaths is the same, regardless of the number of rescuers.

When performing CPR alone, the lay rescuer must remember to give only compressions for adults, children, and infants until an AED arrives. When two rescuers are available, the second rescuer ventilates and evaluates the effectiveness of CPR. The other rescuer administers cardiac compressions. To facilitate movement, each rescuer should assume the appropriate rescue position on opposite sides of the victim. For an adult and child, the compression-to-ventilation ratio is the same as for a single rescuer (30 : 2), and the timing for compressions is “one and two and three and four and five” (a rate of 100 times/min). In infants, two rescuers should use a compression-to-ventilation ratio of 3 : 1 with 90 compressions and 30 breaths delivered per minute (120 events/min). Each breath is delivered over half second with exhalation occurring on the next compression.

When two health care providers resuscitate a patient, the individual providing compressions briefly pauses after 30 compressions so that the other person can administer two ventilations. The cycle is repeated without interruption of compressions to check for signs of circulation or response until an AED arrives or until the hospital code team take over CPR. Health care providers should limit interruptions in chest compressions to no longer than 10 seconds except for interventions such as insertion of an advanced airway or defibrillation.

To provide rest for the individual delivering cardiac compressions, the rescuers should change positions every five cycles (approximately 2 minutes). The individual doing cardiac compressions calls for the change, saying “we will change next time” in sequence with compressions. The switch should be accomplished in less than 5 seconds. The cycle continues with the two rescuers in their new positions. Alternatively, to avoid fatigue, teams of three health care providers can be assigned to do chest compression, switching every five cycles of 30 : 2 compression-to-ventilation ratio. The goal is to push “hard and fast” at a rate of 100/min without fatigue diminishing that goal.

Rescue attempts continue until advanced life support is available, the rescuers note spontaneous pulse and breathing, or a physician pronounces the victim dead. A cardiopulmonary emergency is a crisis for the victim and his or her family, and appropriate support and intervention should be provided all individuals affected. Victims who survive CPR should be transported quickly to tertiary care facilities, ideally only after advanced life support is instituted.

Since 1990, the AHA has recommended adding a fourth step to the treatment of cardiac arrest. This step involves early defibrillation after CPR has been initiated. The rationale is as follows:

Studies have shown that survival rates are highest when immediate bystander CPR is provided and defibrillation occurs within 5 minutes after SCA.¹²

The AHA recommendation is that automated external defibrillators (AEDs) be made available to individuals expected to respond to emergencies, such as police, security personnel, ski patrol personnel, flight attendants, and first-aid volunteers (Figure 34-12). Early defibrillation has already proven to be effective in saving lives of people who otherwise may have not been successfully resuscitated.¹² After appropriate training and implementation of the CABs, this step is inserted as the letter D, for defibrillation. This step should be initiated within 2 minutes of when CPR is begun. EMS providers arriving at the scene of a cardiac arrest should give a period of CPR (five cycles, or about 2 minutes) before checking a rhythm and attempting defibrillation. If the EMS provider witnesses the collapse or for in-hospital situations, the rescuer should use the defibrillator as soon as it is available. In an adult drowning victim or a victim of FBAO who becomes unconscious, a health care provider working alone may give about five cycles (approximately 2 minutes) of CPR before activating the emergency response system.⁴

Personnel employed at high-acuity hospitals may not be equipped with AEDs because access to ACLS is readily available, usually within minutes of the code being called. However, low-acuity hospitals, skilled nursing facilities, and other medical facilities that do not have a code team on the premises would benefit from AEDs. RTs working at such facilities should inquire whether one is on the premises and, if so, where it is located and how it functions. If an AED is not present, a recommendation should be made to the administration of the facility to purchase one. The AHA recommends that an AED be available wherever CPR is likely to be performed.

VF cardiac arrest is less common in children than adults and accounts for 5% to 15% of pediatric and adolescent arrests.13,14 The AHA recommends use of an AED for children older than 1 year who are in cardiac arrest and encourages the use of a pediatric dose-attenuator system if one is available. If such a system is unavailable, a standard AED is recommended. The standard doses recommended by the AHA for manual defibrillation of children are 2 J/kg for the first attempt and 4 J/kg for subsequent attempts.¹⁵ Research has shown that lower energy (120 to 200 J) biphasic waveform shocks have equivalent or higher success in terminating VF than three stacked monophasic waveform shocks delivering escalating energy of 200 J, 300 J, and 360 J.¹⁶ AEDs should be deployed in locations where there is a high incidence of witnessed SCA, such as airports, casinos, and sports facilities.

Automated External Defibrillators

AEDs function more in a semiautomated fashion; the device only recommends that a shock be delivered, rather than initiating one automatically. Fully automatic defibrillators are available but are used only in special circumstances. Adhesive electrodes from the AED are attached to the patient. When all of the equipment is hooked up, the “Analyze” button should be pressed to begin. A rhythm recognition program analyzes the patient’s rhythm. If it detects ventricular tachycardia (VT) or VF, it advises the rescuer through voice and visual prompts that a shock be delivered. If a shock is indicated, the rescuer should “Clear” the patient and press the “Shock” button. After pressing the shock button, the rescuer should deliver five cycles of CPR beginning with chest compression using a 30 : 2 compression-to-ventilation ratio.

The rescuer should not delay chest compressions by stopping to recheck the rhythm or pulse. The rhythm is checked by the AED after five cycles (approximately 2 minutes) of CPR have been completed. The rescuers should be prepared to initiate another five cycles of CPR immediately after a second shock has been delivered. The rescuer administering chest compressions should be changed every 2 minutes. The rescuer providing 2 minutes of chest compressions should be prepared to deliver a shock as soon as he or she removes the hands from the victim’s chest. The second rescuer should be in position to start chest compressions as soon as the shock is delivered. If no shock is advised by the AED, the AED voice prompt should instruct the rescuer to resume CPR immediately starting with chest compressions. If the message reads “No shock indicated,” CPR should be performed for 1 to 2 minutes, and then the rhythm analysis should be repeated. A 1- to 2-minute period of CPR after a no-shock prompt from the AED delivers O₂ and metabolic substrates to the myocardium, increasing the probability that a perfusing rhythm will occur. The rescuer should not be concerned that chest compressions might trigger the return of VF in the presence of a postshock organized rhythm.¹⁷ Figure 34-13 indicates how the AED is used by the rescuer.

 Rule Of Thumb

Patients in VF or pulseless VT cardiac arrest should receive only one shock followed immediately by five cycles of CPR before the pulse and rhythm are rechecked.¹⁵

Evaluating Effectiveness of Cardiopulmonary Resuscitation

CPR providers need to judge continuously both the effectiveness of CPR and the victim’s response. Ventilation can be evaluated by observing visible rise and fall of the victim’s chest during mouth-to-mouth resuscitation. Air that is escaping can be heard and felt during exhalation. Researchers at the AHA 2005 CPR and emergency cardiovascular care consensus conference reached the following conclusions regarding the effectiveness of chest compressions:¹⁸

The cycle time is 600 msec if the chest is compressed at a rate of 100 compressions/min. The time to deliver 30 compressions is 18 seconds if the compression rate is held constant at 100 compressions/min. It takes a rescuer 4 seconds to deliver two breaths with a 1-second inspiratory time and a 1-second expiratory time. Assuming 2 seconds are lost switching from compressions to ventilations, the total ventilation time is 6 seconds. The CPR cycle time is 24 seconds; 2.5 cycles/min would optimally deliver 75 compressions and five breaths. The AHA has encouraged the use of CPR prompts after studies showing compression and ventilation rates are frequently too fast or slow.19,20 Every effort possible must be made to decrease the number of interruptions in chest compressions.

Hazards and Complications

The most common complications that occur with CPR are worsening of existing neck or spine injuries, gastric inflation and vomiting, trauma to internal structures during chest compressions, and problems associated with the removal of foreign objects to clear an obstructed airway.

Contraindications to Cardiopulmonary Resuscitation

A pulseless, apneic patient dies within 4 to 6 minutes without intervention. Fear of further harm should never influence the decision to begin CPR. CPR is contraindicated only when the patient is obviously biologically dead (as noted by such findings as rigor mortis). In the hospital, CPR is contraindicated when a valid “do not resuscitate” order is in effect or when a properly executed living will (advance directive) specifically requests that CPR not be initiated.

Health Concerns and Cardiopulmonary Resuscitation

Laypeople and health care professionals are concerned regarding possible transmission of infectious diseases, such as AIDS, during CPR.²⁶ In one survey, 45% of the physicians and 80% of the nurses who responded indicated that they would refuse to provide mouth-to-mouth ventilation for a stranger.²⁷ The actual risk of disease transmission during mouth-to-mouth ventilation is very small. No reports on transmission of HIV, hepatitis B virus, hepatitis C virus, or cytomegalovirus were found.²⁸ However, the reluctance to initiate CPR poses a clear threat to the effectiveness of early intervention in life-threatening emergencies, which affects the public as a whole. A bystander who is not trained in CPR should provide hands-only (chest compression only) CPR, with an emphasis on “push hard and fast,” or follow the directions of the emergency medical dispatcher.⁴

Health care providers with a duty to provide CPR should follow the guidelines established by the U.S. Centers for Disease Control and Prevention (CDC) and the Occupational Safety and Health Administration. These recommendations include the use of latex gloves, masks, and goggles. Mechanical barrier aids to ventilation (e.g., masks, filters, valves) also have been suggested to allay fear and to protect the rescuer. However, these devices require training to be used properly, are not universally available, and may not be as effective as mouth-to-mouth ventilation.

Although technically blood or body fluids can be exchanged through mouth-to-mouth ventilation, CDC surveillance of job-related contraction of AIDS has never discovered such an incident.²⁸ Other infectious diseases, such as herpes simplex and tuberculosis, may present a higher risk to the rescuer, but few cases have been reported. Although the risk of transmission is believed to be low, health care providers who perform mouth-to-mouth ventilation on someone suspected to have tuberculosis should obtain a follow-up evaluation using standard approaches. In addition, any health care provider who might hesitate to provide mouth-to-mouth ventilation to a victim in need should always carry (and know how to use) an appropriate barrier device for this purpose. Equipment contaminated with blood or other body fluids during a resuscitation effort should always be discarded in appropriate receptacles or thoroughly cleaned and disinfected according to hospital protocols.

Treating Foreign Body Airway Obstruction

Early recognition of FBAO is critical. Foreign bodies may cause partial or complete obstruction. Partial obstruction may allow nearly adequate air exchange, in which case the patient remains conscious and coughing. As long as air exchange is present, the patient should be reassured and allowed to clear his or her own airway by coughing. If partial obstruction persists, or air exchange worsens, the EMS system should be activated. Poor air exchange exists when the patient has a weak or ineffective cough, increased inspiratory difficulty, or cyanosis.

With a completely obstructed airway, the patient commonly clutches at his or her throat. This is known as the universal distress signal for foreign body obstruction. A person with a complete obstruction cannot talk, cough, or breathe and is in dire need of emergency intervention using abdominal thrusts, chest thrusts, back blows, or a combination of two or more maneuvers.

Several procedures can be used to obtain a clear passageway if attempts to open a victim’s airway are unsuccessful or if a foreign body is observed but cannot be removed from the mouth or pharynx. For adults and children, the procedure for health care providers for clearing a foreign body is the abdominal thrust. The rescuer should attempt back blows first for infants with an obstructed airway; if these are unsuccessful, the rescuer should try chest thrusts. Chest thrusts may be used in place of abdominal thrusts on women in advanced stages of pregnancy and on markedly obese individuals. Both abdominal thrusts and chest thrusts normally are followed by a visual check and manual removal of any observed obstructing foreign material.

Abdominal Thrusts (Heimlich Maneuver)

Forceful thrusts applied to the epigastrium can dislodge an obstruction caused by a food bolus, vomitus, or other foreign body. Quick thrusts to the abdomen rapidly displace the diaphragm upward, increasing intrathoracic pressure and creating expulsive expiratory airflow. As with a normal cough, this expulsive airflow may be sufficient to expel the foreign body from the airway. The procedure for performing abdominal thrusts on adults and children is as follows (Figure 34-14):

1. If the victim is sitting or standing, stand behind the victim and wrap your arms around his or her waist. Make a fist with one hand and place the thumb side midline on the abdomen slightly above the navel and well below the tip of the xiphoid process (see Figure 34-14). Grasp the fist with the other hand and deliver a quick upward and inward thrust. Each thrust should be a separate and distinct movement. Repeat the process until the obstruction is removed or the victim loses consciousness.

2. If an adult victim with FBAO becomes unresponsive, the rescuer should move the patient to the ground, activate the EMS system, and begin CPR. Each time the mouth is opened during cycles of compressions and ventilation, the rescuer should look into the victim’s mouth for FBAO and remove it; this should be done without increasing the time to deliver two breaths (approximately 6 seconds). The routine use of blind finger sweeps to remove FBAO in adults, children, and infants is not recommended by the AHA.4,11

3. A conscious victim who is alone can attempt to dislodge the foreign body with self-administered abdominal thrusts, performed by pressing his or her fist into the abdomen or pushing the abdomen against a firm surface such as a counter top, sink, chair back, railing, or tabletop.

Internal Organ Damage

The major hazard associated with abdominal thrusts that are performed when an individual has choked and lost consciousness is possible damage to internal organs, such as laceration or rupture of abdominal or thoracic viscera.²⁹ The body of clinical data regarding choking is largely retrospective and anecdotal. Abdominal thrusts have been recommended for relief of FBAO in adults and children since 1975 based mostly on early anecdotal case reports. Abdominal thrusts are recommended by the AHA and several other resuscitation councils for use for unresponsive adult and child (but not infant) victims. Abdominal thrusts are not recommended for infants younger than 1 year because of their relatively unprotected abdomens and large livers. Rational conjecture and common practices suggest that back blows may loosen obstruction so that subsequent abdominal or chest thrusts may relieve obstruction. The risk of internal organ damage from abdominal thrusts in a conscious patient can be minimized by the rescuer placing his or her arms and fist below the victim’s xiphoid process and lower margin of the ribs.

Back Blows and Chest Thrusts

Because abdominal maneuver can easily cause abdominal injury when applied to infants, a combination of back blows and chest thrusts should be used to clear foreign bodies from the upper airway. Back blows alone may create sufficient force to dislodge trapped objects, but if this is ineffective, the back blows should be followed with five chest thrusts. The rescuer should continue inspecting the airway until the airway is restored. This procedure is as follows (Figure 34-15):

1. Back blows can be administered to infants more efficiently if the child is held straddled over one arm with the head lower than the body.

2. Use the flat portion of your hand to deliver gently, but quickly, five back blows between the shoulder blades.

3. If the back blows do not clear the infant’s airway, turn the infant over and institute a series of five chest thrusts. Similar to abdominal thrust, chest thrust creates a rapid increase in intrathoracic pressure, aiding expulsion of the foreign body. Chest thrusts for infants are performed in the same manner and at the same location as cardiac compressions but at a slower rate.

4. Try to clear the airway between attempts to expel the foreign body. First, visually inspect the oral cavity and remove any foreign matter that can be seen. Deep blind finger sweeps of the mouth of an infant, child, or adult are not recommended.

Support for Oxygenation

Although expired air ventilation provides an acceptable level of oxygenation, low cardiac output, pulmonary shunting, and abnormalities during CPR lead to hypoxia. Hypoxia results in anaerobic metabolism and metabolic acidosis. Metabolic acidosis impedes the action of certain drugs and can diminish the effectiveness of electrical therapies. For these reasons, the highest possible concentration of O₂ should be administered as soon as possible. Concerns about O₂ toxicity are not valid during this period of resuscitation.

During ACLS, supplemental O₂ is normally given through accessory devices designed to support ventilation. The ability of these devices to provide high fractional inspired oxygen (FiO₂) is a key factor in judging their performance.

Airway Management

Accessory equipment designed to provide airway management during ACLS includes a variety of masks and artificial airways.

Pharyngeal Airways

Pharyngeal airways can help restore airway patency and maintain adequate ventilation, in particular, when using a bag-mask device. A properly placed pharyngeal airway also may help provide access for suctioning. Pharyngeal airways should be used only after BLS methods have successfully opened and cleared the airway.

Pharyngeal airways restore airway patency by separating the tongue from the posterior pharyngeal wall. Two types of pharyngeal airways are used in clinical practice: (1) oropharyngeal airway and (2) nasopharyngeal airway.

Oropharyngeal airways come in many different sizes to fit adults, children, and infants. Figure 34-17 shows the two most common oropharyngeal airway designs: (1) the Guedel airway (see Figure 34-17, A) and (2) the Berman airway (see Figure 34-17, B). Both types have an external flange, a curved body that conforms to the shape of the oral cavity, and one or more channels. The Guedel airway has a single center channel, whereas the Berman airway uses two parallel side channels.

To choose the correct size airway, the clinician should place the devices on the side of the patient’s face with the flange even with the patient’s mouth. The correct size airway measures from the corner of the patient’s mouth to the angle of the jaw following the natural curve of the airway.

Because insertion of an oropharyngeal airway can provoke a gag reflex, vomiting, or laryngeal spasm, these devices generally are contraindicated for conscious or semiconscious patients. They also are contraindicated when there is trauma to the oral cavity or the mandibular or maxillary areas of the skull. These airways should never be placed when either a space-occupying lesion or a foreign body obstructs the oral cavity or pharynx.

Two techniques may be used to insert an oropharyngeal airway. In the first method, the tongue is displaced away from the roof of the mouth with a tongue depressor. The curved portion of the airway is slipped over the tongue, following the curve of the oral cavity.

In the second approach, the jaw-lift technique is used to help displace the tongue. The oropharyngeal airway is rotated 180 degrees before insertion. In this manner, the airway itself helps separate the tongue from the posterior wall of the pharynx. As the tip of the airway reaches the hard palate, it is rotated 180 degrees, aligning it in the pharynx.

In either approach, incorrect placement can displace the tongue, pushing it farther back into the pharynx and worsening the obstruction. Oropharyngeal airways must be inserted carefully and by trained personnel only. As shown in Figure 34-17, C, when properly inserted, the tip of an oropharyngeal airway lies at the base of the tongue above the epiglottis, with the flange portion extending outside the teeth. Only in this position can the device properly maintain airway patency.

Endotracheal Intubation

An advanced airway allows the rescuer to achieve one or more of the following goals:

1. Deliver ventilations that are not synchronous with chest compressions

2. Restore airway patency

3. Maintain adequate ventilation

4. Isolate and protect the airway from aspiration

5. Provide access for clearance of secretions

6. Provide an alternative route for administration of selected drugs

Endotracheal intubation is the preferred method for securing the airway during CPR. When positioned properly, an endotracheal tube can maintain a patent airway, prevent aspiration of stomach contents, permit suctioning of the trachea and main stem bronchi, facilitate ventilation and oxygenation, and provide a route for drug administration.

Attempts to intubate the trachea must never interfere with providing adequate ventilation and oxygenation by other means. Only highly trained personnel should perform endotracheal intubation, and each attempt should not exceed 30 seconds because ventilation is absent during the procedure. Adequate ventilation and oxygenation must be provided between attempts. Figure 34-18 shows a cuffed orotracheal tube properly positioned in the trachea. It is being used with a manual bag-mask device to provide ventilation and oxygenation. Adequate ventilation and oxygenation can be provided with 10 to 12 breaths/min.

RTs should be trained in endotracheal intubation techniques, as applied in both emergency life support and mechanical ventilation situations. Details about the necessary equipment, procedures, and short-term and long-term complications of endotracheal intubation are provided in Chapter 33.

Ventilation

Accessory equipment used to support ventilation in advanced life support includes manual and O₂-powered resuscitators. Manual resuscitators, also called bag-mask devices, are available for adults, children, and infants. Conversely, O₂-powered resuscitators are strictly limited to adult application and are not discussed in this chapter.

Bag-Mask Devices

One-way valves on bag-mask devices should be simple, dependable, and jam-free. All health care professionals responding to a cardiac arrest call should be familiar and skilled in the use of such a device for support of ventilation and oxygenation. Application of the bag-mask device is best performed with the practitioner positioned at the head of the victim, using the head-tilt maneuver to maintain the airway (Figure 34-19). The rescuer delivers V_T adequate to produce visible chest rise (6 to 7 ml/kg or 500 to 600 ml) over 1 second. Using this smaller V_T decreases airway pressure and minimizes risk of gastric inflation.

It is important to deliver the two breaths during CPR over only 3 to 4 seconds so that the optimal number of chest compressions per minute can be delivered (75 compressions/min, rate of delivery 100 compressions/min). The 30 : 2 compression-to-ventilation ratio allows for only five breaths to be delivered per minute. It is critical that all five breaths be delivered with visible chest rise. After an advanced airway replaces the face mask, the ventilatory rate should be 8 to 10 breaths/min during CPR. Slower rates of 6 to 8 breaths/min might be needed for patients with chronic obstructive pulmonary disease (COPD) to prevent air trapping and the development of auto–positive end expiratory pressure (PEEP). Ventilatory rates greater than 12 breaths/min are not recommended during CPR because they lead to increased intrathoracic pressure, impeding venous return to the heart during chest compressions,³⁰ and hyperventilation.

The rescuer delivers each breath over 1 second and should not attempt to synchronize ventilations with the chest compressions. Nonsynchronized delivery of ventilation and compressions allows the number of chest compressions delivered per minute to increase from 75 to 100 (33% increase) and breaths delivered per minute increase from 5 to 10 (100% increase). After restoration of a perfusing rhythm, the ventilation rate should be 10 to 12 breaths/min delivered over 1 second.

Bag-mask devices combine a mask with a self-inflating bag and a nonrebreathing valve mechanism. These devices may be used to ventilate patients by applying the mask over the patient’s mouth and nose or by attaching the self-inflating bag directly to an endotracheal tube or other advanced airways. All devices are capable of providing ventilation with air or with supplemental O₂. Bag-mask devices can provide 100% O₂ when properly applied. Although initially designed as adjuncts for emergency life support, they are used extensively in other respiratory care settings, in particular, in the areas of airway management and continuous mechanical ventilation.

Design

Figure 34-20 is a schematic of a typical bag-mask device, showing gas movement and valve action during both the inhalation-compression and exhalation-relaxation phases. The key components shown in this schematic are the nonrebreathing valve (left), the bag itself, the O₂ inlet and bag inlet valve (to the right of the bag), and the O₂ reservoir tube (far right).

During exhalation (see Figure 34-20, A), gas flows out from the patient’s lungs through the nonrebreathing valve into the atmosphere. At the same time (while the bag expands), the intake valve opens, and 100% O₂ flows into the bag from both the reservoir and the O₂ inlet.

During the inhalation phase (see Figure 34-20, B), the bag is compressed manually, causing bag pressure to increase. This increase in bag pressure simultaneously closes the inlet valve and opens the nonrebreathing valve, forcing gas into the patient. While the bag inlet valve is closed, O₂ coming in through the O₂ inlet goes into the reservoir tube, where it is stored for the next breath.

Restoring Cardiac Function

Perfusion support techniques, such as chest compressions, can restore circulation only temporarily. ACLS must go beyond simple perfusion support to identify and remove, or relieve the underlying cause of cardiac failure; this is done by combining ECG monitoring with pharmacologic and electrical therapies.

Electrocardiogram Monitoring

Because most cases of cardiac arrest are caused by arrhythmias, ECG monitoring should be started as soon as the necessary equipment and personnel arrive. Monitoring may be done with either standard electrocardiographic equipment or the quick-look paddles now available on most defibrillators.

Given their important role in ACLS, RTs must be skilled in recognizing arrhythmias. Although an experienced RT may be able to interpret quickly gross arrhythmias appearing on electrocardiographic monitors at the bedside, these skills develop only after much practice with actual rhythm strips. Chapter 17 presents a review of ECG interpretation. The reader should focus on the following arrhythmias:

• VT

• VF

• Sinus tachycardia

• Sinus bradycardia

• Sinus arrest

• Premature atrial contractions

• Supraventricular tachycardia (SVT)—a classification of arrhythmias, including but not limited to:

• Sinus tachycardia

• Atrial flutter

• Atrial fibrillation

• Atrioventricular blocks—first degree, second degree types I and II, and third degree

• Premature ventricular contractions

• Pulseless electrical activity (PEA)

• Systole

This section briefly discusses the arrhythmias closely associated with CPR conditions, including SVT, VT, VF, and PEA.

Supraventricular Tachycardia

The term supraventricular tachycardia is commonly used to describe any tachycardia not of ventricular origin. This grouping can include sinus tachycardia, atrial tachycardia, junctional tachycardia, atrial flutter, and atrial fibrillation (with rates >100 beats/min). These individual supraventricular arrhythmias are identified by ECG and treated accordingly (Figure 34-21).

A more specific form of SVT involves rapid impulse formation caused by a reentry mechanism that develops in the atria or atrioventricular junction. Normally, a single impulse from the sinoatrial node traverses the atria and continues down into the ventricles, causing depolarization and contraction. In reentry, an ectopic focus disrupts this normal conduction. The impulse not only moves down to the ventricles but also returns to the atria. This pattern repeats in a self-perpetuating, or circular, manner.

Typically, this form of SVT results in heart rates between 160 beats/min and 220 beats/min. The rhythm is regular, which distinguishes it from rapid atrial fibrillation. However, because of its rapid rate, P waves may not be seen. If identifiable, the P waves appear abnormal. In addition to the rate and regular rhythm, SVT is characterized by a normal QRS complex. At very high rates, the ventricles may not have enough time to fill completely. Incomplete ventricular filling can result in decreased cardiac output, congestive heart failure, and tissue hypoxia. SVT may deteriorate to VT if it is not recognized and treated in a timely manner.

The treatment of SVT varies according to the clinical situation (Figure 34-22). If a patient with SVT is ill or unstable, the treatment of choice is immediate synchronized electrical cardioversion as described elsewhere in this chapter. If the patient is stable, other interventions are tried before cardioversion is considered. The most common nonelectrical treatment for SVT is vagal stimulation by carotid artery massage or Valsalva maneuver. If these attempts are ineffective and the patient remains stable, drugs such as adenosine, diltiazem, verapamil, or beta blockers (as a second-line agent) may halt SVT. These drugs work primarily on the nodal tissue by slowing ventricular response to atrial arrhythmias, or they block the reentry SVT that travels through the atrioventricular node.

Ventricular Tachycardia

VT occurs when one or more irritable foci within the ventricle discharge at rapid rates, creating the appearance of a prolonged chain of premature ventricular contractions. Rates typically range from 140 to 220 beats/min and usually are regular (Figure 34-23).

Although VT may come and go in brief episodes, or paroxysms, it is always a sign of a serious underlying pathologic condition and should be treated immediately. In stable patients, VT is managed with amiodarone.³¹ Alternative drugs for wide-complex regular tachycardias are procainamide and sotalol.³² For patients with sustained VT who exhibit hypotension, ischemic chest pain, shortness of breath, decreased consciousness, or signs of pulmonary edema, immediate synchronized cardioversion is indicated (Figure 34-24). Patients with sustained VT in full cardiac arrest are treated similarly to patients with VF.

Ventricular Fibrillation

VF is a rapid, sustained, and uncontrolled depolarization of the ventricles. During VF, the ECG is characterized by irregular, widened, and poorly defined QRS complexes, known as coarse VF (Figure 34-25, A). These complexes widen farther and lose amplitude, resembling a coarse asystole, which now is defined as fine VF (Figure 34-25, B). Rather than exhibiting coordinated contractions, the ventricles quiver in a totally disorganized manner. Cardiac output during VF is zero. The rapid decrease in cardiac output produces an acute cerebral hypoxia, often manifested by convulsions. VF is uniformly fatal if not corrected immediately.

Many conditions cause VF. The most common causes include electrical shock, anesthesia, mechanical irritation of the heart, severe hypoxia, myocardial infarction, and large doses of digitalis or epinephrine. Regardless of the cause, VF constitutes a true emergency. Patient survival depends on immediate provision of ACLS, especially electrical defibrillation. Early defibrillation is the major determinant of survival in cardiac arrest caused by VF.

Pulseless Electrical Activity

PEA that is not shockable can result from several reversible causes (Figure 34-26). The immediate primary treatment is uninterrupted CPR for about 2 minutes with vasopressor given simultaneously. The best secondary approach is to identify and treat reversible causes (e.g., for hypovolemia, replace volume; for tension pneumothorax, needle decompression). In asystole or slow PEA, atropine administration can be considered (see Figure 34-26).

Electrical Therapy

The following three general types of electrical therapy are used in emergency cardiac care: (1) unsynchronized countershock, or defibrillation; (2) synchronized countershock, or cardioversion; and (3) electrical pacing.

Unsynchronized Countershock (Defibrillation)

When an electrical shock of appropriate strength is applied to the myocardium, all myocardial fibers simultaneously depolarize. Theoretically, when all cells depolarize, the cells that spontaneously fire at the fastest rate should be able to regain control and pace the heart. Normally, the sinus node spontaneously depolarizes most rapidly. After electrical shock, the sinus node should discharge first and capture all parts of the myocardium as the depolarization wave travels through the still, silent heart.

Defibrillation is an unsynchronized shock used to depolarize the myocardial fibers simultaneously. It is the definitive treatment for both VF and pulseless VT. If one of these arrhythmias is present, and the proper equipment and trained personnel are available, defibrillation of the patient should be performed immediately.

If a biphasic defibrillator is available, the AHA recommends an initial energy level of 120 to 200 J for defibrillation of adults and 2 to 4 J/kg for defibrillation of children and infants.¹⁵ For children older than 1 year, if a shockable rhythm persists after five cycles of CPR, the rescuer should give one shock (4 J/kg) and resume compressions immediately. AHA 2010 guidelines recommend a 360-J shock for monophasic defibrillators for the first and subsequent shocks.¹⁵ If VF recurs, the previously successful energy level should be used for subsequent shocks, and compressions should be resumed immediately.

Electrode paddle size and placement are important in ensuring that the full energy of the countershock is applied. For adults, paddles should be 8 to 12 cm in diameter; adult paddles are adequate size for children older than 1 year. Normally, one paddle is placed below the clavicle and just to the right of the upper portion of the sternum, with the other positioned on the midaxillary line to the left of the left nipple. Alternatively, one paddle may be placed on the left precordium, with the other positioned posteriorly under the patient, behind the heart. Paddles should be prepared with conducting gel and applied with firm pressure (approximately 25 lb).

Synchronized Countershock (Cardioversion)

Cardioversion is similar to defibrillation, with two major exceptions. First, the countershock is synchronized with the heart’s electrical activity (the R wave). Synchronization is necessary because electrical stimulation during the refractory phase (part of the T wave) can cause VF or VT. Second, the energy used during cardioversion usually is less than the energy applied during defibrillation.

Cardioversion is considered when a patient with an organized arrhythmia producing a high ventricular rate exhibits signs or symptoms of cardiac decompensation. These so-called tachyarrhythmias include SVT, atrial flutter, atrial fibrillation, and monomorphic VT with pulses. Cardioversion is ineffective for treatment of junctional tachycardia or multifocal atrial tachycardia.¹⁵

If the arrhythmia is not causing serious signs or symptoms, drug therapy is used first. However, if the patient is hypotensive, exhibits signs of decreased consciousness or pulmonary congestion, or complains of chest pain, cardioversion is indicated.

Electrical Pacing

Another application of electrical therapy uses intermittently timed, low-energy discharges to replace or supplement the natural pacemaker of the heart. There are two primary types of electrical pacing. First, the electrical discharge can be delivered from an external power pack through wires inserted into the patient’s chest wall (transcutaneous, or transthoracic, pacing). Alternatively, wire electrodes may be floated through the large veins and implanted directly inside the heart (transvenous pacing). Because it can be started quickly, transcutaneous pacing is the method used most often in emergency cardiac care.

Pacemaker therapy is used to treat sinus bradycardias that produce serious signs and symptoms and that do not respond to atropine (Figure 34-27). Electrical pacing also is used to manage second-degree type II and third-degree heart block. Electrical pacing also can be used to treat some tachyarrhythmias. In these cases, the pacemaker is set to discharge faster than the underlying rate. After a few seconds, the pacemaker is stopped to allow the heart’s intrinsic rate to return. This is called overdrive pacing. Although overdrive pacing has shown promise in treating certain types of SVT and VT, pharmacologic intervention (when the patient is stable) and cardioversion (when the patient is unstable) remain the treatments of choice.

Because defibrillation can cause damage to permanent pacemakers, care should be taken not to place the electrode paddles near these devices. After a patient with a permanent pacemaker undergoes either cardioversion or defibrillation, the device should be checked for proper functioning. Pacing is not recommended by the AHA for patients in asystolic cardiac arrest because it is ineffective and may delay or interrupt the delivery of chest compressions.¹⁵

Monitoring During Advanced Cardiac Life Support

Although extensive monitoring is used in most critical care settings, monitoring during emergency life support is usually limited to ECG, pulse, blood pressure, and intermittent arterial blood gas (ABG) sampling. Several approaches designed to enhance knowledge of patient status during CPR have been proposed more recently. These include methods to monitor ventilation, oxygenation, and airway status better.

The ECG is the most common and one of the most useful types of monitoring used during ACLS. The ECG provides the basis for selecting various drug and electrical therapies during CPR and helps indicate patient response to these interventions. However, an acceptable ECG rhythm does not mean that cardiac output is adequate. Other indices of perfusion, such as pulse, blood pressure, and skin temperature, are needed to confirm adequate cardiac output.

Patient Care Following Resuscitation

Following cardiac arrest, a patient may exhibit an optimal response, in which case the patient regains consciousness, is responsive, and breathes spontaneously. More often, however, the patient requires support of one or more organ systems. Acidemia associated with cardiac arrest usually improves when normal ventilation and perfusion are restored.

If the patient is conscious and breathing spontaneously after resuscitation, supplemental O₂, maintenance of an IV infusion, and continuous cardiac and hemodynamic monitoring may be all that is necessary. A 12-lead ECG, chest x-ray, ABG analysis, and clinical chemistry profile should be obtained as soon as possible. The 2010 AHA guidelines recommend that providers of care after cardiac arrest should “(1) control body temperature to optimize survival and neurological recovery; (2) identify and treat acute coronary syndromes; (3) optimize mechanical ventilation to minimize lung injury; (4) reduce the risk of multiorgan injury and support organ function if required; (5) objectively assess prognosis for recovery; and (6) assist survivors with rehabilitation services when required.”³⁶ The patient should be closely supervised in an intensive care or coronary care unit, especially during the first 24 hours after a cardiac arrest.³⁷

Only in this setting can underlying organ system insufficiency or failure be properly identified and managed.³⁷ The organs most likely to exhibit failure after resuscitation are the lung, heart and vasculature, and kidneys. Central nervous system failure is an ominous sign and generally indicates a failed resuscitation attempt.

Respiratory Management

If the patient remains apneic or exhibits irregular breathing after resuscitation, mechanical ventilation is instituted through a properly positioned endotracheal tube, with an initial O₂ concentration of 100%. ABGs, preferably obtained through an arterial line, are analyzed as needed until the oxygenation and acid-base status of the patient stabilize. ABG analysis also helps differentiate between pulmonary and nonpulmonary (or cardiac) causes of hypoxemia and tissue hypoxia. Mechanical ventilation is adjusted to maintain a normal PaCO₂ level. Hyperventilation is detrimental and should be avoided. Higher ventilatory rates and larger V_T may cause hyperventilation. This hyperventilation may generate increased airway pressures and auto-PEEP, leading to an increase in cerebral venous and intracranial pressures and a decrease in coronary artery and cerebral arterial pressures.³⁸ Cerebral blood flow may decrease, causing increased brain ischemia, if hyperventilation results in increased intrathoracic pressure. For details of the selection and use of mechanical ventilators and appropriate patient monitoring procedures, see Chapters 41 to 46.

Cardiovascular Management

The 12-lead ECG, chest x-ray, clinical chemistry profile, cardiac enzyme results, and current and past drug histories should be reviewed. Invasive hemodynamic monitoring may be needed to monitor blood pressure and cardiac output. This monitoring provides needed data on the adequacy of vascular volumes, left ventricular performance, and overall tissue perfusion. Based on these data, judgments can be made regarding the need for fluid therapy and the selection and use of appropriate drugs.