Chapter 3 Cardiopulmonary Resuscitation

Most of the information provided in this chapter can be reviewed in greater detail by referring to specific guidelines published by the American Heart Association (AHA), in conjunction with the International Liaison Committee on Resuscitation. Please visit the AHA’s website at http://www.heart.org and follow the links to Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (CPR & ECC). Also see the Bibliography at the end of this chapter. This chapter focuses on basic life support (BLS) and the management of pulseless arrest (a part of advanced cardiovascular life support [ACLS]).

1 What is meant by cardiopulmonary resuscitation (CPR)?

To most people, CPR refers to BLS, which encompasses closed-chest compressions and rescue breathing. For health care providers, the term can be much broader and can include

ACLS

Pediatric advanced life support (PALS)

Advanced trauma life support (ATLS)

Thus it is very important for the physician to be specific whenever discussing resuscitation with patients and their families.

2 Is iatrogenic cardiopulmonary arrest very common?

It probably occurs much more often than it really should. Without a doubt, errors of omission and commission contribute to the incidence and poor outcome of in-hospital cardiopulmonary arrests. In a study of 562 in-hospital arrests, a major unsuspected diagnosis was present (and proved by autopsy) in 14% of cases. The two most common missed diagnoses were pulmonary embolus and bowel infarction, which together accounted for 89% of all missed conditions. Retrospective reviews indicate that as many as 15% of in-hospital arrests are probably avoidable. These cases can be attributed to respiratory insufficiency and hemorrhage that are often undetected or diagnosed too late, because aberrations in patients’ vital signs and their complaints (especially dyspnea) are frequently ignored.

Direct iatrogenesis also contributes to in-hospital cardiopulmonary arrests. Almost every procedure, including esophagogastroduodenoscopy, bronchoscopy, central venous line placement, and an abdominal computed tomography scan with contrast, has, on occasion, been associated with an arrest. The injudicious use of lidocaine, sedative-hypnotics, and opiates is primarily responsible for these types of arrests throughout the hospital. Careful hemodynamic monitoring, especially pulse oximetry, by a dedicated practitioner can decrease the occurrence of this easily avoidable complication.

3 What are the four major components of BLS?

Recognition of an unresponsive patient who is not breathing or not breathing in a normal manner

Activation of the emergency medical system with acquisition of an automated external defibrillator (AED)

Closed-chest cardiac compressions with ventilations

Actual defibrillation

4 What is the CAB of resuscitation?

According to all published guidelines, the CAB of resuscitation is compressions, airway, and breathing. This has replaced the old mnemonic of ABCD because initial resuscitation now begins with closed-chest compressions once it has been established that the patient is unresponsive, is not breathing, and has no pulse. After 30 chest compressions, the airway is opened and two breaths are delivered. Thus the sequence is compressions, airway, and breathing (CAB).

5 How is BLS performed?

For any patient in cardiac arrest, the most important steps are to

1. Immediately recognize unresponsiveness

2. Check for lack of breathing or lack of normal breathing

3. Activate emergency response system and retrieve an AED

4. Check for a pulse (no more than 10 seconds)

5. Start cycles of 30 chest compressions followed by two breaths

This applies to all patients, regardless of location (in hospital or out of hospital).

Responsiveness: A quick check for the presence of breathing or lack of normal breathing should be performed when assessing a patient who may be in cardiac arrest. If the patient is unresponsive, then the emergency response system should be activated and an AED or defibrillator should be quickly retrieved (i.e., call 911 or call a code).

Compressions: Because a pulse can be very difficult to assess, it may be necessary to use other clues, such as whether the patient is breathing spontaneously or moving. Regardless, the health care provider should take no more than 10 seconds to check for a definitive pulse at either the carotid or femoral artery. If the patient has no pulse or no signs of life, or the rescuer is unsure, chest compressions should be started immediately. The heel of the hand should be placed longitudinally on the lower half of the sternum, between the nipples. The sternum should be depressed at least 5 cm (2 inches) at a rate of at least 100 compressions per minute. Complete chest recoil is necessary to allow for venous return and is important for effective CPR. The pattern should be 30 compressions to two breaths (30:2 equals one cycle of CPR) regardless of whether one or two rescuers are present. Pulse checks and signs of life should be assessed after every five cycles (equivalent to 2 minutes) of CPR. Once the AED or defibrillator arrives, it should be attached without delay so that an electrical shock can be immediately delivered to improve the likelihood of a return of spontaneous circulation (ROSC).

Airway: With the new 2010 BLS guidelines, the importance of airway management has taken more of a secondary role. The old mnemonic ABCD (airway, breathing, circulation, and defibrillation) with “look, listen, and feel” has been changed to CAB (compressions, airway, and breathing). This change is due to evidence proving the importance of chest compressions and the need to quickly restore blood flow to improve the likelihood of ROSC. Airway maneuvers should still be attempted, but they should occur quickly and efficiently and minimize interruptions in chest compressions. Opening of the airway can be achieved by a simple head tilt–chin lift technique. A jaw thrust maneuver can be used in patients with suspected cervical spine injury. Simple airway devices, such as nasal or oral airways, can be inserted to displace the tongue from the posterior oropharynx. Definitive airway management, such as placement of an endotracheal tube, is an aspect of ACLS and should never be a part of BLS.

Breathing: Although several large out-of-hospital studies have demonstrated that chest compression–alone CPR is not inferior to traditional compression-ventilation CPR, health care providers are still expected to provide assisted ventilation. A lone rescuer, outside the hospital setting, should not use a bag-mask for ventilation, but should use mouth-to-mouth or mouth-to-mask. Care should be taken to avoid rapid or forceful breaths. Delivered tidal volumes are given over a 1-minute period and should be just enough to produce visible chest rise. Large tidal volumes should be avoided because they would promote hyperventilation and decrease preload. Hyperventilation in the patient with cardiac arrest receiving closed-chest compressions has been proved to be detrimental for neurologic recovery.

Defibrillation: An AED or defibrillator should be attached to the patient as soon as possible. Proper electrode pad or paddle placement on the chest wall should be to the right of the upper sternal border below the clavicle and to the left of the nipple with the center in the midaxillary line. If using a portable out-of-hospital AED device, turn the AED on first and then follow the voice commands. If the defibrillator’s electrical output is adjustable, then the initial voltage delivered should be the manufacturer’s recommendation. When this is unknown, 200 J should be used. Immediately after the shock, closed-chest compressions are resumed.

Of note, BLS should ideally be performed only by those persons who have been certified by the AHA, or other similar organization. However, it is not uncommon for 911 operators to provide instruction over the phone when no other qualified individual is nearby. Certification is easily obtained by attending one or two classes taught by qualified instructors. Most communities offer these classes to the general public.

6 How does blood flow during closed-chest compressions?

Two basic models derived from animal studies explain the movement of blood during closed-chest compressions:

In the cardiac pump model, the heart is squeezed between the sternum and spine. Systole occurs when the heart is compressed; the atrioventricular valves close and the pulmonary and aortic valves open, ensuring ejection of blood with unidirectional, antegrade flow. Diastole occurs with the release of the squeezed heart resulting in a fall in intracardiac pressures; the atrioventricular valves open while the pulmonary and aortic valves close. Blood is subsequently drawn into the heart from the venae cavae and lungs.

In the thoracic pump model, the heart is considered a passive conduit. Closed-chest compression results in uniformly increased pressures throughout the thoracic cavity. Forward flow of blood occurs with each squeeze of the heart and thorax because of the relative noncompliance of the arterial system (i.e., they resist collapse) and the one-way valves preventing retrograde flow in the venous system. Both of these models probably contribute to blood flow during CPR.

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