ANESTHETIC ACCIDENTS AND COMPLICATIONS—PREVENTIVE MEASURES

Anesthetic accidents have occurred since the early days of ether and nitrous oxide administration (see Chapter 23 and Chapter 24 ). Wells and Morton described patients who required resuscitative measures during anesthesia. Several near deaths were reported after the October 1846 demonstration. Bigelow's first description of ether anesthesia provides a case report of a patient who nearly died after ether administration and was resuscitated by cold effusions, ammonia inhalation, and syringing of the ears.^[120] Two other cases "failed to be affected by ether." George Hayward^[445] (1791–1863) reported a death after ether inhalation occurring in August 1847. Snow's book^[446] on chloroform appeared in 1858 and discusses a number of frightening cases and deaths during administration of anesthesia. The first such tragedy with chloroform struck in 1848, when an anesthetic was given to a 12-year-old girl, Hannah Greener, for a minor surgical procedure. The postmortem examination of this young girl was inconclusive, but the anesthetic was thought to have been administered properly. The controversy surrounding this death has occupied the minds of numerous anesthesiologists for the past 150 years.^{[447] [448]}

Most anesthetic deaths were not attributed to the agent or the method of administration but simply resulted from "the patient not taking the anesthetic well." A frequent diagnosis after death during anesthesia was the vague syndrome of "status lymphaticus."^[449] Although this was a convenient phrase for the anesthesiologist to use, it thwarted a review of causes that might help to prevent future disasters. A major change occurred in anesthetic practice with the introduction of morbidity and mortality conferences that examined the causes of anesthetic accidents. Originally introduced by Ralph Waters in Madison, Wisconsin, these meetings sought to carefully scrutinize anesthetic complications, thereby shifting the focus of investigation from the patient to the provider and the equipment used to deliver the anesthetic. The postanesthesia care unit, originally designated the recovery room, was promoted for safety reasons by two anesthesiologists from Washington, D. C., in an influential paper in 1951,^[450] and these units are now mandated by the accreditation process for all hospitals.

Curtis L. Mendelsohn, an obstetrician from New York City, presented one of the early useful reports of anesthetic complications. In 1945, he reported 66 cases of aspiration of stomach contents during general anesthesia for labor and delivery.^[451] He further observed that aspiration of even small volumes of low pH stomach contents in rabbits would result in fatal pulmonary edema. Since his classic descriptions, the syndrome of acid aspiration is often called the Mendelsohn syndrome.

The cuffed endotracheal tube was one solution to the problem of acid aspiration. Authur Guedel and Ralph Waters were motivated to devise a truly closed system of anesthetic administration using carbon dioxide absorption, which would conserve anesthetic gases and body heat. Their 1928 report of the cuffed endotracheal tube^[410] achieved these goals with the added benefit of protection of the tracheobronchial tree from aspiration. Others had devised cuffed endotracheal tubes before them,^[452] but Guedel and Waters used a novel method to demonstrate and promote the safety features of the cuffed tube. Guedel anesthetized and then intubated his pet dog, appropriately named Airway, with a cuffed endotracheal tube. The dog was submerged in a water tank for several minutes and then removed and awakened unharmed. The demonstration was repeated at several meetings, and this publicity enhanced the rapid acceptance of the new endotracheal tube. The cuffed tube is regarded today as an effective measure for preventing acid aspiration.

In 1961, B. Sellick^[453] described the rapid sequence induction for prevention of acid reflux. The method involves the application of firm pressure over the cricoid

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Although few defects in apparatus could occur while applying ether onto a folded towel, the increasing complexity of the anesthetic delivery system brought with it the unfortunate side effect of equipment failure. One of the earliest equipment defects occurred with the simple Morton inhaler. George Hayward reported that a defective intake port led to restricted breathing, lividity, and convulsions in an elderly woman having a leg amputated in January 1847.^[445] Wrong gas, wrong agent, wrong concentration, sticky or jammed valves, contaminated agents, and hypoxic mixtures—all of these and others were reported as routes to disaster.

Open discussions of these complications led to adjustments in equipment design.^[455] Pin indexing of gas cylinders and hoses eliminated the possibility of introducing air or nitrous oxide into the oxygen lines of the gas machine. In-line oxygen analyzers were placed on the inspiratory limb of the breathing circuit. Fail-safe devices prevented the use of any machine that was not supplied with oxygen. Uniform connectors were adopted, thereby providing rapid assembly of breathing circuits. The American Society of Anesthesiologists (ASA) initiated the formation of the Z-79 Committee of the American Standards Institute. This committee recommended safe construction of endotracheal tubes, needles, and connectors. The American Society for Testing and Materials (ASTM), a not-for-profit organization that writes standards for materials and products (through their committee designated F-29), describes the requirements used in the design of safe anesthetic gas machines. The International Standards Organization is also developing global standards for anesthesia equipment.

Further progress in reducing anesthetic related complications resulted from the formation of professional societies, specialty journals, and certification boards. One of the earliest journals limited exclusively to anesthesiology was Current Research in Anesthesia and Analgesia, founded in 1922 largely through the efforts of Francis Hoffer McMechan (1879–1939).^[456] McMechan was an anesthesiologist who had retired at an early age for health reasons and devoted the remainder of his career to promoting organizational and political causes of anesthesiologists. An independent American Board of Anesthesiology was formed in 1940 and, through its examination process, continues to elevate standards of anesthetic care. Specialty societies of professional anesthesiologists have formed in most countries practicing modern anesthetic techniques. The ASA was founded as the American Society of Anesthetists in 1936 and currently has approximately 38,000 members. Anesthesiology, the official journal of the ASA, began publication in 1940. National anesthesia societies promote safe anesthetic practice through annual meetings, refresher courses, and direct communication with members. Practice guidelines for general anesthesia, obstetric anesthesia, and ambulatory surgery are sent annually to each member of the ASA. Subspecialty societies in cardiac, ambulatory, transplant, pediatric, neurosurgical, and obstetric anesthesia have been formed and strive to improve the anesthetic management of patients within their respective groups.

The Anesthesia Patient Safety Foundation (APSF) was conceived in October 1985, largely through the organizational efforts of Ellison C. Pierce, Jr. This highly successful organization promotes safe anesthesia practice through research grants and periodic mailings to members. As a result of these efforts, anesthesiologists have been recognized as forerunners in promoting agendas that enhance patient safety.^{[457] [458]}

Improved monitors have provided the anesthesiologist with methods to fine-tune the anesthetic delivery and detect early signs of danger. Auscultation of the chest, an obligatory skill in the current era, had its beginnings in the early 19th century, when Rene T. Laennec^[459] used a cylindrical paper tube to listen to the chest. The term stethoscope was a combination of the Greek words stetho ("chest") and scope ("I see") and was used by anesthesia providers as early as 1896 to monitor cardiac and respiratory sounds. The esophageal stethoscope, introduced in 1954 by C. Smith,^[460] has been used extensively to detect breathing circuit disconnects, airway obstruction, and bronchospasm in the anesthetized patient.

A. E. Codman (1869–1940) of Boston introduced the first anesthetic records in 1894, and the practice was encouraged by Harvey W. Cushing (1869–1939), who promoted recordings of blood pressure, pulse, and respiratory rate on all of his cases.^[461] Practice guidelines for minimal monitoring standards were first issued^[462] at the nine teaching hospitals at Harvard Medical School, and 2 years later, the ASA issued similar standards that included measures of oxygenation, ventilation, circulation, and body temperature. Electronic monitoring has significantly contributed to the safe practice of anesthesiology. Continuous electrocardiography displays, often with ST-segment analysis, are attached to most anesthesia machines. Endtidal gas analysis, using infrared technology developed in the 1940s, is in common use. Thermistors offer a continuous measure of core body temperature, thereby providing an early warning for the rare but potentially lethal syndrome of malignant hyperthermia. ^[463] An awareness of complications associated with hypothermia in the anesthetized patient and the use of methods to prevent its occurrence have contributed significantly to a safer environment for the surgical patient.^{[464] [465]}

Some complications that may seem trivial to the provider can be highly significant for the patient. Surveys have shown, for example, that postoperative nausea and vomiting are feared complications in a large percentage of patients contemplating surgery.^[466] Progress has been made in eliminating this complication through the use of agents with less emetogenic potential. An increased understanding of the neurochemical substrates that regulate the vomiting reflex has resulted in specific therapies to prevent or lessen the gastrointestinal side effects of general anesthetics and opioids.^[467] Dopamine antagonists and 5-HT₃ antagonists have been particularly cost effective. ^[468]

The increasing use of muscle relaxants by anesthesia providers has led to the terrifying complication of an awake, paralyzed patient who is fully aware of

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Allergic reactions to drugs can be life-threatening. Anaphylaxis (meaning "without protection") is appropriately named, especially for anesthetized patients, because the symptoms of hypotension and bronchospasm can have many causes, and specific treatment can often be delayed. The syndrome was described in 1913 by Charles R. Richet^[475] (1850–1935), who was studying the toxicology of various fish poisons and observed the rapid onset of death in dogs that more than 15 days earlier had withstood a much larger dose of the toxin. Richet postulated that an immune response had developed in the interim and produced a fatal reaction to the injection. The role of histamine and vasomotor instability was described in 1932,^[476] and this understanding led to the role of vasopressors and antihistamines as treatment.

Even though enormous progress has been achieved toward the goal of zero anesthetic-related morbidity and mortality, no such claim can yet be made at any institution. In part, this is because more extensive procedures are being performed on sicker patients than was the case 100 years ago. In 1914, Gwathmey (see Fig. 1-18D ) reported the rate of 0.01% for anesthetic-related mortality with ether anesthesia,^[146] a surprisingly low figure considering the anesthetic methods in use at the time. However, in 1914, they did not perform extensive procedures such as liver and heart transplantations on patients with life expectancies (without surgical intervention) of only a few weeks. Anesthesiologists have recently focused on postoperative as well as intraoperative pain, and this extension carries with it additional risks to the anesthesia providers.

The quest for improving the perianesthetic experience is far from over. A physician has only to ask patients about the experience of having a major surgical procedure to conclude that it is far from pleasant, even in the absence of complications. It is futile to attempt to summarize the current hardships a surgical patient must undergo in the modern hospital or even attempt possible solutions. Change will occur—that is certain—and if we can learn anything from the past 150 years, there are possibilities for improvement and modalities of practice that we cannot even imagine today. Some methods in use today will appear nonsensical to future practitioners. As portions of the preceding historical survey demonstrate, one barrier to progress is failure by those entrenched in their routines and biases to recognize a breakthrough when it occurs. Perhaps the smarter we are, the more we fail to see our failures. In 1775, while Joseph Priestley^[477] was hopelessly lost in the phlogiston theory of combustion, we find these words written in his classic manuscript, Experiments and Observations of Different Kinds of Air: "The more ingenious a man is, the more effectually he is entangled in his errors; his ingenuity only helping him to deceive himself, by evading the force of truth."

Truth in clinical medicine is perhaps even more difficult to recognize than answers to the questions that chemists were contemplating at the end of the 18th century. However, anesthesiology has made remarkable progress in the more than 150 years since the public demonstration of ether anesthesia, and this progress should continue until the safe elimination of all unwanted pain from human experience has been attained.