Emergency Cardiovascular Life Support



Emergency Cardiovascular Life Support


Thomas A. Barnes




Respiratory therapists (RTs) play a vital role in emergency cardiovascular life support. In hospitals, RTs serve as key members of the medical emergency teams, also known as rapid response teams. In addition to managing the airway, RTs often provide ventilatory and circulatory support; drug and electrical therapy; and monitoring immediately before, during, and after a cardiac arrest.


In the community, RTs may also be certified cardiopulmonary resuscitation (CPR) instructors, extending their knowledge to laypeople through organizations such as the American Heart Association (AHA) or the American Red Cross. Mastery of an extensive knowledge base and the development of various, sometimes difficult manual skills are required for teaching and performing CPR. The practitioner is encouraged to obtain further competencies by completion of formal courses in CPR, advanced cardiovascular life support (ACLS), pediatric advanced life support, and neonatal resuscitation program.



Causes And Prevention Of Sudden Death


Sudden cardiac arrest (SCA) is a leading cause of death in many parts of the world.1 In the United States and Canada, approximately 350,000 people per year experience SCA and receive an attempted resuscitation.2 The incidence of out-of-hospital SCA is 50 to 55 per 100,000 persons per year.2 The incidence of in-hospital cardiac arrest is 3 to 6 per 1000 admissions. Pulseless ventricular rhythms are the first manifestation of cardiac arrest in 25% of cases.2,3 Successful resuscitation depends on immediate CPR and delivery of a shock before pulseless ventricular rhythms deteriorate into asystole. In cases of SCA related to asphyxia secondary to trauma, drug overdose, or upper airway obstruction, CPR with chest compressions and ventilation before the shock is critical.



Basic Life Support


The goal of basic life support (BLS) is to restore ventilation and circulation to victims of airway obstruction and respiratory or cardiac arrest. These skills can be used by a single practitioner to restore ventilation and circulation until the victim is revived or until ACLS equipment and personnel are available. The steps for administering BLS by a single health care practitioner are as follows:



Steps 4 through 7 are referred to as the CABDs of resuscitation—circulation, airway, breathing, and defibrillation. Table 34-1 summarizes the CABDs of CPR for adults, children (1 year old to puberty), and infants (<1 year old).



TABLE 34-1


Steps for Cardiopulmonary Resuscitation (CPR) in Adults, Children, and Infants





























































Procedure Adult Child Infant
Compressions
Where to check pulse (limit pulse check to <10 sec) Carotid artery Carotid or femoral artery Brachial artery
Hand placement Heel of one hand on sternum in center of chest, between nipples. Second hand on top of first with hands overlapped and parallel Lower half of sternum with heel of one hand or with two hands (for larger children). Do not compress over xiphoid Sternum with two fingers placed just below nipple line in center of chest
Compression-to-ventilation ratio One or two rescuers 30 : 2 One rescuer 30 : 2; two rescuers 15 : 2 One rescuer 30 : 2; two rescuers 15 : 2
Cycles of compression-to-ventilation 5 5 5
Depth of compressions (push in hard and fast, allow chest to recoil fully) 2 in At least one-third anteroposterior diameter of chest or 2 in (5 cm) At least one-third anteroposterior diameter of chest or image in (4 cm)
Compression rate 100/min 100/min 100/min
Breathing
Obstructive procedure Responsive: If mild, allow victim to clear the airway by coughing. If severe, repeat abdominal thrusts until foreign body is expelled, or the choking victim becomes unresponsive. Consider chest thrusts if abdominal thrusts are ineffective, if rescuer is unable to encircle victim’s abdomen, or if victim is in the late stages of pregnancy Same as for adult Responsive: If mild, allow infant to clear the airway by coughing. If infant is unable to make a sound (severe obstruction), deliver five back blows (slaps) followed by chest thrusts repeatedly until object is expelled or infant becomes unresponsive. Abdominal thrusts should not be done on infants because they may damage the largely unprotected liver
  Unresponsive: Carefully move victim to the ground, immediately activate EMS system, and begin CPR, but look into the mouth before giving breaths. If a foreign body is seen, it should be removed. Follow ventilation with chest compressions   Unresponsive: Activate EMS system and begin CPR, but look into the mouth before giving breaths. If a foreign body is seen, it should be removed. Follow ventilation with chest compressions
Rescue Breathing
Palpable pulse, but no spontaneous breaths or inadequate breathing 10-12/min, 1 breath every 5-6 sec 12-20/min, 1 breath every 3-5 sec, if palpable pulse ≥60/min 20/min, 1 breath every 3 sec, if palpable pulse ≥60/min


image



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.



Restoring Circulation


Determining Pulselessness


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):





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.710 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.




Chest Compressions Under Special Circumstances


The following unique circumstances require modification of the normal procedures for applying cardiac compressions: near drowning, electrical shock, and patients with implanted pacemakers or defibrillators.






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 (VT) between 700 ml and 1000 ml is ideal for most adults. A VT 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 VT 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.



Automated External Defibrillation


Early Defibrillation


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

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Jun 12, 2016 | Posted by in RESPIRATORY | Comments Off on Emergency Cardiovascular Life Support
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