Anesthesiologists have contributed many of the elements of modern CPR and continue to be active investigators and teachers in the field. Discoveries leading to current CPR practice have a long history recorded in many famous works.¹,² The earliest reference may be the Bible story of Elisha breathing life back into the son of a Shunammite woman (2 Kings 4:34). In 1543, Andreas Vesalius³ described tracheotomy and artificial ventilation. William Harvey’s manual manipulation of the heart is well known. Early teaching of resuscitation was organized by the Society for the Recovery of Persons Apparently Drowned, founded in London in 1774. The combined techniques of modern CPR developed primarily from the fortuitous assemblage of innovative clinicians and researchers in Baltimore in the 1950s and early 1960s. Building on the long history of contributions from around the world, these investigators laid the framework for current CPR practice. In the late 1950s, mouth-to-mouth ventilation was established as the only effective means of artificial ventilation.⁴,⁵,⁶,⁷ The internal defibrillator was developed in 1933,⁸ but it was not applied successfully until 1947.⁹ It was another decade before general use was made possible by the development of external cross-chest defibrillation.¹⁰,¹¹ Despite these advances, widespread resuscitation from cardiac arrest was not possible until Kouwenhoven et al.¹² described success with closed-chest cardiac massage in a series of patients. The final major component of modern CPR was added in 1963, when Redding and Pearson¹³ described the improved success obtained by administering vasopressor drugs.

Cardiovascular disease remains the most common cause of death in the industrialized world. Although cardiovascular mortality has been declining in the United States since the mid-1960s, >35% of all deaths are due to cardiovascular causes.¹⁴ Of the 860,000 annual cardiovascular deaths, approximately half are related to coronary artery disease, the majority are sudden deaths and 70% occur out of the hospital or in hospital emergency departments. Thus, CPR teaching and research tend to focus on myocardial ischemia as the primary cause of cardiac arrest. However, anesthesiologists are more likely than other practitioners to deal with causes other than myocardial infarction. CPR is symptomatic therapy, aimed at sustaining vital organ function until natural cardiac function is restored. The details of effective resuscitation technique are important. However, search for a remediable cause of the arrest must not be lost in excessive attention to mechanics.

Brain adenosine triphosphate (ATP) is depleted after 4 to 6 minutes of no blood flow. It returns nearly to normal within 6 minutes of starting effective CPR. Studies in animals suggest that good neurologic outcome may be possible from 10- to 15-minute periods of normothermic cardiac arrest if good circulation is promptly restored.¹⁵,¹⁶ In clinical practice, the severity of the underlying cardiac disease is the major determining factor in the success or failure of resuscitation attempts. Of those factors under control of the rescuers, poor outcomes are associated with long arrest times before CPR is begun, prolonged ventricular fibrillation (VF) without definitive therapy, and inadequate coronary and cerebral perfusion during cardiac massage. CPR begun by bystanders can more than double survival.¹⁷ However, bystanders provide CPR only 25% to 30% of the time in sudden cardiac arrest. Optimum outcome from VF is obtained only if basic life support is begun within 4 minutes of arrest and defibrillation applied within 8 minutes.¹⁸ The importance of early defibrillation has been known for decades and is emphasized in CPR practice.¹⁹,²⁰ What is not as well recognized is the tendency to interrupt chest compressions frequently during a resuscitation attempt. Studies of emergency medical systems suggest that chest compressions are performed <50% of the time during a typical out-of-hospital resuscitation, being interrupted for pulse checks, intubations, starting intravenous catheters, defibrillation attempts, and moving the victim.²¹ Because blood flow falls rapidly with cessation of compressions and resumes slowly with reinstitution of compressions, these interruptions are a major contributor to poor survival rates.

With an effective rapid-response emergency medical system, initial resuscitation rates of 40% and survival to hospital discharge of 10% to 15% are possible after out-of-hospital arrests,¹⁸,²⁰ although the median reported survival to discharge with any first recorded rhythm is 6.4%.²² Rates for survival to discharge from in-hospital arrest are about 18% in adults and 27% in children.²³ Within the hospital, the operating room is the location where CPR has the highest rate of success. Cardiac arrest occurs appro-ximately 7 times for every 10,000 anesthetics.²⁴ The cause for the arrest is anesthesia related, approximately 4.5 times for every 10,000 anesthetics, but mortality from these arrests is only 0.4 per 10,000 anesthetics. Thus, resuscitation is successful approximately 90% of the time in anesthesia-related cardiac arrests.

Although institution of CPR is standard medical care when an individual is found pulseless, terminally ill patients have become increasingly concerned about inappropriate application of life-sustaining procedures, including CPR. Through living wills and other instruments, patients have begun placing limitations on medical treatment to include do not resuscitate (DNR) orders. Such requests are generally accepted, even welcomed, by health care workers. However, the operating room is one area of the hospital where DNR orders continue to cause ethical conflicts between medical personnel and patients.²⁵,²⁶ There are ethically sound arguments on both sides of the issue as to whether DNR orders should be upheld in the operating room.

The patient’s right to limit medical treatment, including refusing CPR, is firmly established in modern medical practice based on the ethical principle of respect for patient autonomy. A terminally ill patient can reject heroic measures such as resuscitation and still choose palliative therapy. If a surgical intervention will ameliorate symptoms or improve quality of life, there is no reason to withhold this treatment. Operative intervention increases the
risk of cardiac arrest, and the patient may not want the burden of surviving in a worse condition than preoperatively. The possibility of death under anesthesia may be viewed as especially peaceful. Thus, the time that the DNR order provides the greatest protection against unwanted intervention is during surgery.

Despite these rather strong arguments for treating a DNR status in the operating room the same way it is treated elsewhere in the hospital, many operating room personnel are at least a little uneasy caring for these patients. Many surgeons require that DNR orders be suspended during the perioperative period or assume consent to surgery includes such suspension. There are multiple reasons for the reluctance to accept DNR status during surgery and anesthesia. Approximately 75% of cardiac arrests in the operating room are related to a surgical or anesthetic complication, and resuscitative attempts are highly successful.²⁴ Ethically, surgeons and anesthesiologists feel responsible for what happens to patients in the operating room: primum non nocere (first, do no harm). Although the physicians are highly diligent in monitoring and managing changes in the patient’s status, complications and arrests do occur. Honoring a DNR order under these circumstances is frequently viewed as failure to treat a reversible process, and hence, tantamount to killing. This is an ethically sound view if the cause of arrest is readily identifiable and easily reversible and if treatment is likely to allow the patient to fulfill the objectives of coming to surgery.²⁵

Institutionally, these ethical conflicts should be addressed by adoption of clear policies by hospitals.²⁷ For the individual patient, conflicts can be resolved by communication among the patient, family, and caregivers. A mutual decision can often be reached to suspend or severely limit a DNR order in the perioperative period if the patient understands the special circumstances of perioperative arrest, that interventions are brief and usually successful, and that the physicians support the patient’s goals in coming to surgery and values in desiring not to prolong death. Many interventions commonly used in the operating room (mechanical ventilation, vasopressors, antidysrhythmics, blood products) may be considered forms of resuscitation in other situations. The only modalities that are not routine anesthetic care are cardiac massage and defibrillation. Therefore, the specific interventions included in a DNR status must be clarified with specific allowance made for methods necessary to perform anesthesia and surgery.

The major components of resuscitation from cardiac arrest are airway, breathing, circulation, drugs, and electrical therapy (ABCDE). Traditionally, these have been divided into basic life support (BLS) for those elements that can be performed without additional equipment—basic airway management, rescue breathing, and manual chest compressions (Fig. 58-1)—and advanced cardiac life support (ACLS), encompassing all the cognitive and technical skills necessary for resuscitation (Fig. 58-2). The lines between BLS and ACLS have tended to blur recently with the

introduction of public-access automatic external defibrillators (AEDs) and the recognition that careful attention to uninterrupted, effective chest compressions improves outcome more than any advanced therapy. To stress these important elements, the American Heart Association (AHA) has adopted a simplified adult BLS algorithm as shown in Figure 58-3. In the following sections, each of the components involved in resuscitation will be reviewed separately, followed by a discussion of combining the elements for the best outcome.

The problem of airway obstruction caused by the tongue in the unconscious patient is familiar to the anesthesiologist. The techniques used for airway maintenance during anesthesia are applicable to the cardiac arrest victim. The primary method recommended to the public is the same head tilt–chin lift method commonly employed in the operating room.²⁸ The head is extended by pressure applied to the brow while the mandible is pulled forward by pressure on the front of the jaw, lifting the tongue away from the posterior pharynx. The jaw thrust maneuver (applying pressure behind the rami of the mandible) is an effective alternative. Properly inserted oropharyngeal or nasopharyngeal airways can be useful before intubation, recognizing the danger of inducing vomiting or laryngospasm in the semiconscious victim. Tracheal intubation provides the best airway control, preventing aspiration and allowing the most effective ventilation. However, it should not be performed until adequate ventilation (preferably with supplemental oxygen) and chest compressions have been established. A number of alternative airways designed for blind placement have been described and the laryngeal mask airway and the esophageal-tracheal Combitube (see Chapter 27) have been recommended for use during cardiac arrest by individuals who are not skilled laryngoscopists.²⁹ When other methods of establishing an airway are unsuccessful, translaryngeal ventilation or tracheotomy by cricothyroid puncture may be necessary.

The standard approach to the unresponsive victim is to follow opening the airway with ventilation. When ventilation is provided in the rescue setting, mouth-to-mouth or mouth-to-nose ventilation is the most expeditious and effective method immediately available. Although inspired gas with this method will contain approximately 4% carbon dioxide and only approximately 17% oxygen (composition of exhaled air), it is sufficient to maintain viability.

This discussion of drug therapy is confined to the use of drugs during CPR attempts to restore spontaneous circulation. The use of drugs to support the circulation when there is mechanical cardiac function is discussed elsewhere (see Chapters 15 and 39). During cardiac arrest, drug therapy is secondary to other interventions. Effective uninterrupted chest compressions and defibrillation, if appropriate, should take precedence over medications. Establishing intravenous access and pharmacologic therapy should come as soon as possible but after these critical interventions are established. Although vasopressors are firmly established as improving survival in animal models and there is some evidence of improved early resuscitation in humans, there is no strong evidence that they improve long-term survival in human cardiac arrest.⁷⁹,⁸⁰ The most common drugs and the appropriate adult doses are shown in Table 58-2. In addition, pharmacologic and other therapeutic approaches for the treatment of bradycardia and tachycardia are in Figures 58-5 and 58-6.