Key words: Anesthesia: risks; safety. History: anesthesia patient safety.
IT is indeed an honor and a privilege to deliver this eponymous presentation, the 34th Rovenstine Lecture.
In preparation for this lecture, I have read most of the previous published discourses in the series. By custom, speakers begin with a few comments about Dr. Rovenstine, who was born in Indiana in 1895 and died in New York City in 1960. Rovey, as he was affectionately called by his friends, was urged to enter the young field of anesthesia by Arthur Guedel, who was then on the medical faculty at Indiana and who sent him to train with Ralph Waters at Wisconsin. Rovenstine was one of Waters' first two residents. Several previous speakers have examined their anesthesia "family" descent from Waters and Rovenstine. Although I never met either, I may be part of the family because the chairman at Pennsylvania, where I trained, was Robert Dripps, also a resident with Waters and later with Rovenstine.
Dr. Waters dispatched Rovey to Bellevue Hospital at the beginning of 1935, responding to an urgent request by the Chief Surgeon of the New York University Division. Over the next several years, Emery A. Rovenstine became famous as an anesthesiologist, as far as I know, the only one ever profiled in The New Yorker. [1-3]Perhaps his greatest role was in training young, scholarly anesthesiologists to become chairmen of academic departments. In addition, Dr. Rovenstine must be considered one of the key figures in the creation of anesthesiology as a full medical specialty. Perry Volpitto and Leroy Vandam, in their 1982 book The Genesis of Contemporary American Anesthesiology, place the early giants into two groups, first, the visionaries, including Guedel and Waters. The second, the activators, contains Rovenstine.
As the foregoing comments suggest, Rovenstine's professional life calls forth the enduring themes of leadership, vision, and dedication to the advance of medical practice. These themes are the real spirit of the Rovenstine Lectures, and they provide a purpose and continuity that remain strong and relevant--long after the passage of time has diminished the early linkages of professional kinship and memory. In keeping with this essential spirit, my lecture today will once again visit the basic themes. I will do so by exploring the pursuit of patient safety in anesthesia, an objective that has been the chief goal in my professional career. Although my remarks will present an admittedly personal view, I hope they will convey some general lessons and insights that will make this lecture a worthy tribute to Dr. Rovenstine and the lecture series.
The first day I administered anesthesia as a resident in training was on July 1, 1954, in one of the gynecology operating rooms at the Hospital of the University of Pennsylvania. The instructor was James Eckenhoff, simply a wonderful teacher. Years later, in a lecture given before the Royal Society of Medicine on the importance of leadership, he discussed its role in promoting safety. .
What was it like to practice anesthesia in 1954? How safe did it seem? The department at Pennsylvania was a major proponent of cyclopropane anesthesia, but the other available agents included diethyl ether, divinyl ether, ethylchloride, trichlorethylene, nitrous oxide, ethylene, and on rare occasion, chloroform. Use of intravenous thiopental was common, as was rectal anesthesia with a variety of agents such as tribromoethanol (Avertin), paraldehyde, or chloral hydrate. Single-dose and continuous spinal anesthesia with procaine or tetracaine were widely employed, even for upper abdominal surgery.
Intravenous solutions were seldom begun until after the patient was asleep. Cyclopropane induction usually was performed with only the agent and oxygen. With ether, the patient was given 100% N2O for several minutes. The resultant hypoxia plus the addition of carbon dioxide to the circuit produced hyperventilation, hastening ether uptake. Induction frequently was time-consuming. Anesthesia for tonsillectomy was with open drop ether and no endotracheal tube. I clearly remember one incident when Dripps, demonstrating ether induction to a group of medical students, saw his patient, a strapping young male, sit up and step off of the table.
At Barnes Hospital in St. Louis, where I had been a surgical intern, the time required for ether induction, before I could prepare the patient, was often 30 min or more. Impatience with this vexing delay was one of the factors that pushed me into becoming an anesthesia resident. Some of the surgeons at Barnes performed thyroidectomies while the nurse anesthetist gave only thiopental, total doses approaching 2 g or more. These patients, of course, slept for a considerable period after surgery. Dripps, in contrast to Beecher at the Massachusetts General Hospital, encouraged use of the recently available neuromuscular blocking drugs, d-tubocurare, succinylcholine, gallamine, and decamethonium. However, prolonged blockade with decamethonium was common; because we had no ventilators, it fell on the residents to ventilate the patient's lungs postoperatively in the then new recovery room, using an anesthesia machine.
Intubation of the trachea was not common, except when necessary, as in anesthesia for thoracic surgery. Even thyroid resection was performed while anesthesia was administered via a mask. I remember worrying about having one of my fingers cut if the surgeon slipped with his knife. When residents were allowed to intubate the trachea, more often than not the tube had no cuff; rather, the pharynx was stuffed with gauze. If the anesthesiologist did want a cuffed tube, it was necessary to insert the cuff over the end of the endotracheal catheter. As you can well imagine, it was not unusual for the cuff to be dislodged, sometimes to remain in the trachea.
What of the anesthesia machines? At Pennsylvania, several models were used, including Ohio, Heidbrink, and Forreger, with its water manometer. No resident was ever fully inducted into the club until he had opened the oxygen valve on a water manometer Forreger with the flowmeter previously left fully on, thus blowing water all over the operating room. There were no piped gases; the tanks on the machine were, therefore, all-important.
What of intraoperative monitoring? It was not much different from the days of John Snow, who in the 1850s had encouraged observation of the pulse, respirations, and pupils. The only additional techniques in common use were the Riva Rocca blood pressure measurement and occasionally, in pediatric patients, a precordial stethoscope. Electrocardiograms were unavailable except under the most rare circumstance, when an old mahogany Sanborn machine would be wheeled into the operating room from the electrocardiogram station. However, it almost never worked because of the effect electrical interference had on the stylet. I never saw a sample of blood for blood gas analysis obtained in a clinical setting, because blood gas measurements could only be made in a research laboratory using the Van Slyke manometric apparatus. Cardiac arrest, not an unusual occurrence, was treated with open thoracotomy; closed chest compression had not evolved. Defibrillation was with alternating current.
I well remember the arrival, while I was at Pennsylvania, of the first machine with Lucien Morris' copper kettle. Suddenly, residents were able to give 60% ether instead of struggling with warm water around the glass vaporizer trying to reach an ether concentration of 5%. As a result, the incidence of ether overdose skyrocketed. Almost every Monday afternoon at the complications conference there was at least one presentation of near cardiac arrest. Moreover, in those days, in all anesthesia departments, I am sure, when a patient did not survive, the families were simply told that "old Joe" just didn't tolerate the anesthesia--"too bad."
By today's standards, cardiac anesthesia was particularly primitive. Because there were no plastic intravenous catheters, a number-14 metal needle was inserted in the dorsum of each foot, where the likelihood of dislodgement was less than in the arm. Monitoring, again, consisted of Riva Rocca blood pressure measurement, observation of respiration, and a finger on the pulse. Often, blood pressure could be obtained only by observing oscillations. Electrocardiography was rarely attempted. Thomas Cannard, one of our staff anesthesiologists, built the first permanent electrocardiogram machine in our operating rooms from a kit.
Recovery rooms were by that time in use in many American hospitals, but they were small and primitive. They were not to be found in the United Kingdom or Europe. If a patient were cyanotic, it was difficult to know whether it was central cyanosis or a result of peripheral vasoconstriction due to shivering. Some anesthetists, to make the differential diagnosis, would scratch the chest with a needle, observing whether the resultant bleeding was bright or dark blood.
Anesthesia machines were certainly less safe than today. Heidbrink flowmeters with disc floats were difficult to read accurately because the calibration was too small. There was no standardized arrangement for the gas flowmeters; the oxygen flowmeter was sometimes on the left side, sometimes in the middle, and sometimes on the right. Pin indexing was new; not all machines had been fitted with the pins. Moreover, sometimes the pins were dislodged, allowing attachment of the wrong tank. This situation was a setup for catastrophe, because each machine often had cylinders of oxygen, nitrous oxide, cyclopropane, ethylene, carbon dioxide, and helium. Ventilators were not available, except for primitive ones with a single pressure setting or foot-operated bellows.
What, then, was the status of anesthesia patient safety in 1954? From a somewhat humorous standpoint, it was well described in the preface of Stanley Sykes' wonderful essays, "The First Hundred Years of Anesthesia." He quotes Lincoln, from the Gettysburg Address: "It is for us, the living, rather to be dedicated here to the unfinished work which they who fought here have thus so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us, that. . .we here highly resolve that these dead shall not have died in vain."
An enormous awakening was also at hand in 1954. It began with the huge controversy that greeted the publication of the paper by Beecher and Todd. "A Study of the Deaths Associated with Anesthesia and Surgery," which appeared in the July 1954 issue of Annals of Surgery in my first month as an anesthesia resident. I remember the anger in Dr. Dripps' voice as he refuted the data, especially the statement that the study "strongly suggests an inherent toxicity" in the neuromuscular blocking drugs. The publication was one of the first to add a denominator when considering anesthesia deaths; evaluations of the previous 100 yr were limited to analyses that did not consider the number of anesthetics administered. Beecher examined nearly 600,000 anesthetics administered over 5 yr in ten university hospitals. He noted who the anesthesia caregivers were, what techniques and agents were used, and whether the trachea was intubated. The incidence of anesthesia mortality was found to be 3.7 per 10,000 anesthetics, with anesthesia as a primary cause.
One year later, also in Annals of Surgery, 16 distinguished American anesthesiologists published a "Critique of "A Study of the Deaths Associated with Anesthesia and Surgery." They stated, "[We] believe that many of the important conclusions drawn by Beecher and Todd are not justified on the basis of the statistics presented. . .," and suggested that missing data in the Beecher paper, such as site of operation, depth of relaxation required, duration of anesthesia and operation, and severity of surgical trauma, negated many of the conclusions. They, as had Dripps and Manny Papper at Columbia, objected strongly to the suggestion that use of "curare" results in higher mortality rates. A few years later, in a retrospective study initiated after the Beecher paper, Dripps analyzed the role of anesthesia in surgical mortality at the University of Pennsylvania. Among some 33,000 patients given either a general anesthetic to which neuromuscular blockers were added or a spinal anesthetic, there were no deaths attributable to anesthesia in ASA physical status I patients, although the overall mortality rate with anesthesia as the primary cause was 11.7 per 10,000 anesthetics.
Here, then, were two decades of numerous studies worldwide of anesthesia deaths, with mortality rates ranging from 1 to 12 per 10,000 anesthetics. Anesthesia study commissions, examining postoperative deaths, proliferated. A well known one was directed by Otto Phillips in Baltimore, where during a 5.5-yr period ending in 1959, they found anesthesia to be the principal cause of mortality in some 6% of the deaths and a contributing factor in 13%. Phillips declared death from anesthesia a major public health problem. He opened a review of anesthesia mortality with an anonymous quotation: "You members of the medical profession, gentlemen, are in a favored position--the world acclaims your successes and flowers cover your failures." .
Perhaps the most important result in all of this was the increased interest among anesthesiologists in improving anesthesia outcomes. In 1962, I became interested in anesthesia patient safety. I had joined Leroy Vandam at the Peter Bent Brigham Hospital as de facto Vice Chairman. In his inimitable way, one day he assigned me the subject, "anesthesia accidents," to be given as a resident's lecture. I still have notes in my files from that talk, which began as a collection of anesthesia mishaps that I knew about personally, somewhat akin to a chapter in Sykes' Essays, "37 Little Things Which Have All Caused Death."
Arthur Keats, who had been an anesthesia resident at the Massachusetts General Hospital during the period that the Beecher study was undertaken, criticized anesthesia mortality studies. He argued in 1970 that, "The relative risk of all anesthetics commonly used today remains unknown." He stated that, "for most deaths, assignment of the relative roles of anesthesia, surgery and patient disease is based on retrospective assumptions, hindsight judgment, bias, and incomplete information." He opened his paper with a quotation from Sir William Osler, "Errors in judgement must occur in the practice of an art which consists largely in balancing probabilities."
Later, Dr. Keats continued his thesis, in the 1978 Crawford W. Long Memorial Lecture at Emory and the 1990 Seldine Lecture. He reemphasized that we in anesthesia are unable even to define an anesthetic death. Bias often exempts anesthetic agents from adequate risk/benefit analysis. He particularly criticized the classic 1948 article, "Deaths Under Anesthetics," by the eminent British anesthetist, Robert Macintosh, who stated that all anesthetic deaths are preventable, the result of errors. Dr. Keats wrote, "Thirty years of self flagellation in the form of anesthetic mortality studies have generated an abundance of 'errors'. . ., all published estimates of the incidence of error or the incidence of anesthetic deaths are now unacceptable. . .Demonstration of a cause-effect relationship is absolutely essential if any secure knowledge of mechanisms of anesthetic deaths is to be achieved." He cited the discovery of new mechanisms for anesthesia death, such as malignant hyperthermia and succinylcholine-induced hyperkalemia. Dr. Keats concluded that we must rid ourselves of error bias.
William Hamilton, Keats' great friend and hunting companion of many years, challenged, in an editorial, the implication that drugs per se are responsible for an important number of anesthetic deaths. He agreed that much bias had been present in anesthesia mortality evaluations, especially equating departure from current clinical practices with error. In contrast, Dr. Hamilton believed that anesthesiologists had carefully evaluated risk/benefit concepts after review of death reports, as in halothane hepatitis, for example. He stated that, whereas we previously tended to blame drugs or the patient's disease when anesthesia went amiss, we correctly recognize the ever increasing importance of human error; "To blame an undiscovered or unexplained acute toxic effect of a drug, an idiosyncratic reaction, or divine intervention, as would appear to be Dr. Keats' thrust, is very questionable when we know that physician errors can result in mortality." He stated that the controversy between Keats and him concerned the relative role of drugs as problems in opposition to management errors on the part of the anesthesiologist and concluded that ". . .it is important to know whether anesthetic deaths attributable to error amount to 10 or 90 per cent. . . .In my view error is near the 90% end." I have reviewed the debate between Keats and Hamilton because it remains relevant. Moreover, I also believe the scale is closer to the 90% end.
The almost exclusive use of crude anesthesia mortality studies to evaluate anesthesia outcome was brilliantly interrupted in 1978 with the publication of Jeffrey Cooper's first paper describing critical incident analysis applied to anesthesia. The technique, used in military aviation during World War II, had a profound effect on aviation safety that continues even today.
Cooper simply discarded evaluation of mortality rates as the major measure of negative anesthesia outcome. Rather, he stated, "Factors associated with anesthetists and/or factors that may have predisposed anesthetists to err have, with a few exceptions, not been previously analyzed. Furthermore, no study has focused on the process of error--its causes, the circumstances that surround it, or its association with specific procedures, devices, etc.--regardless of final outcome." Data for this first study using the critical incident technique in anesthesia were obtained from 47 interviews of staff and resident anesthesiologists at a large teaching hospital. In a followup paper published in 1984, the database was enlarged to include 139 anesthesiologists, residents, and nurse anesthetists from four Boston hospitals in which 1,089 descriptions of preventable critical incidents were collected. Their 1978 tables listing the distribution of frequent critical incidents and associated factors are classics (Table 1and Table 2).
Based on his observations. Cooper proposed corrective strategies to lessen the likelihood of an incident occurring. .
1. Train, educate, and supervise.
2. Use appropriate monitoring instrumentation and vigilance.
3. Recognize the limitations influencing individual performance.
4. Establish and follow preparation and inspection protocols.
5. Assure equipment performance.
6. Design and organize work space.
7. Act on incident reports--eliminate the pitfalls.
The "20/20" television program segment "The Deep Sleep, 6,000 Will Die or Suffer Brain Damage" aired on Thursday, April 22, 1982. The announcer opened the program, "If you are going to go into anesthesia, you are going on a long trip and you should not do it, if you can avoid it in any way. General anesthesia is safe most of the time, but there are dangers from human error, carelessness and a critical shortage of anesthesiologists. This year, 6,000 patients will die or suffer brain damage." After scenes of patients who had experienced anesthesia mishaps, the program stated, "The people you have just seen are tragic victims of a danger they never knew existed--mistakes in administering anesthesia." In another example shown on the program, a patient was left in coma after the anesthesiologist's error in turning off oxygen rather than nitrous oxide at the end of an anesthetic. Later in the program, the following dialogue ensued. An unidentified spokesperson advised Tom Jerriel, one of the hosts, that "there is a hospital in New York City where there are two anesthesia people covering five operating rooms." Jerriel appeared incredulous and asked "How do they do it?" The spokesperson replied, "Well, they run quickly and pray a lot."
The "20/20" program was a watershed for anesthesia patient safety endeavors. At the time, I was First Vice President of the American Society of Anesthesiologists (ASA) and decided to establish a new ASA committee, the Committee on Patient Safety and Risk Management. Howard Zauder was the first Chairman. The ASA had, of course, been involved in quality assurance for some time with its Committee on Peer Review, but never before had the concept of patient safety been so specifically addressed by our specialty society. Among its first endeavors, the Committee developed a series of patient safety videotapes, still being produced, with me as Executive Producer. The 25th tape, "Perioperative Nerve Injury," just completed by Producer Robert Stoelting, is being shown at the Patient Safety Booth. It will be distributed to all United States anesthesia departments by Glaxo Wellcome.
In 1984, Cooper, Richard Kitz, and I hosted the first International Symposium on Preventable Anesthesia Mortality and Morbidity (ISPAMM), held in Boston. Some 50 anesthesiologists from the United States, Australia, Great Britain, South Africa, and Belgium attended. Debate was loud and strong; controversy among the nations was extensive, especially considering use of monitoring equipment. Perhaps the area of greatest agreement was in the definitions of outcome, morbidity, and mortality (Table 3). That international meeting has been held every 2 yr since.
The Anesthesia Patient Safety Foundation (APSF) was established as a result of the Boston meeting. Considerations of attaching a safety society to other entities, such as the World Health Organization, were rapidly abandoned because of the probabilities that international controversy would prevent effective actions.
The Foundation has sought expert advice from a broad range of professionals outside the ASA--lawyers, pharmaceutical and device manufacturers, risk managers, nurse anesthetists, insurers, and representatives from the Food and Drug Administration, the Joint Commission, the American College of Surgeons, and the American Medical Association--an undertaking certainly not possible in the structured environment of the ASA at that time. The goals remain the same:
1. Foster investigations that will provide a better understanding of preventable anesthetic injuries.
2. Encourage programs that will reduce the number of anesthetic injuries.
3. Promote national and international communication of information and ideas about the causes and prevention of anesthetic injuries.
The quarterly APSF Newsletter, with an estimated circulation of 60,500, is in its 10th year, with John Eichhorn as Editor. The APSF has awarded 34 research grants in patient safety, totaling $1,325,000.
What of more recent mortality studies? Major reports have come from the United Kingdom, where John Lunn and associates established a confidential, anonymous system to report anesthesia deaths associated with surgery. Their initial report was published in 1982. Anesthesia was considered partly or totally causative of mortality in one or two cases per 10,000 and to be totally causative in nearly 1 per 10,000. Of significance was their determination that large numbers of patients were not seen preoperatively by an anesthesiologist, did not have blood pressure recorded intraoperatively, did not have the machine checked by the anesthesiologist before beginning anesthesia, and did not have intraoperative monitoring with the electrocardiogram. The next report in the continuing evaluation was the first edition of the Confidential Enquiry into Perioperative Deaths, arranged by both the Association of Anaesthetists and the Association of Surgeons of Great Britain and Ireland. It examined perioperative deaths occurring during 12 months in three national health service regions. In that period, death attributable to anesthesia alone was only 0.05 per 10,000 anesthetics, a figure far less than the earlier citation. The reviewers decided that, 40% of the time, the anesthetic was less than ideal. Some 10% of fatal operations were judged to have been unnecessary or unjustified.
Another continuing analysis of anesthesia mortality spanning nearly the entire 40 yr of this lecture series is that from New South Wales, Australia. The overall death rate in which factors under the control of the anesthetist caused or contributed to the fatal outcome was thought to be about 2 per 10,000 operations in 1960, 1 per 10,000 in 1970, and 0.5 per 10,000 in 1990.
In the United States, it is not possible to approach examination of anesthesia mortality in the way I just described because of our medical liability climate and nearly ineffectual coroner systems. The important 1985 report by Keenan on cardiac arrest due to anesthesia at the Medical College of Virginia studied, over 15 yr, 160,000 anesthetics in which there were 27 cardiac arrests, an incidence of 1.7 per 10,000 anesthetics. He discovered that the risk for emergency surgery was greater than that for elective surgery, as it was also for pediatric patients versus adult. Failure to provide adequate ventilation was responsible for half of the cardiac arrests.
Why the improvement? It should be noted that the second decade began 5 yr before capnography and pulse oximetry came into common use. One identifiable occurrence in that period was the publication of Cooper's first analysis of critical incidents. Keenan suggested three general explanations for the improvement in outcome: first, use of specific initiatives to detect and prevent hypoxic ventilatory mishaps; second, significant increases in the number and quality of anesthesia trainees; and third, use of better anesthesia techniques.
The ASA Closed Claim study, truly a major American effort to examine anesthesia risk, also arose out of the 1984 Boston International Meeting at which Richard Ward, then Professor of Anesthesiology at the University of Washington, discussed his preliminary findings, examining closed malpractice claims against anesthesiologists in the state of Washington. They were published in a 1984 book, Analysis of Anesthesia Mishaps, edited by Cooper and me. The twin malpractice problems, unavailability of medical liability insurance in the 1970s and the crisis of affordability in the 1980s, suggested the need to examine closed claims on a national basis. I remember working with Ward on revisions to the data collection forms and suggesting that the national project be given to the ASA Committee on Professional Liability, which President Ketcham Morrell did in 1985. Fred Cheney, the Committee Chairman, then as well as now, has noted, "The relationship of patient safety to malpractice insurance premiums was easy to predict. If patients were not injured, they would not sue, and if the payout for anesthesia-related patient injury could be reduced, then insurance rates should follow."* In the beginning it looked as if it would be difficult to get insurance companies to turn over their closed claims data to outside physicians. However, Mark Wood of the Risk Management Services at St. Paul Fire and Marine Insurance Company was looking for someone to review the Company's claims. Wood was also an attendee at the Boston international meeting and was appointed an original member of the APSF Board. Robert Caplan, then also at the University of Washington, joined the Committee to help in the analysis. It was decided that findings should be published in major, peer reviewed journals. Fortunately, early on, local anesthesiologists were able to convince the Massachusetts Joint Underwriting Association, the Doctor's Company of Southern California, and the New Jersey Medical Underwriters to provide data.
The most important information coming out of the Closed Claim Study is contained in the analysis of adverse respiratory events, which constituted the single largest class of injury, some 35% of the total. The first three mechanisms of injury accounted for about three-quarters of the total adverse respiratory events; inadequate ventilation 38%, esophageal intubation 18%, and difficult intubation 17%. The majority of respiratory claims were lodged before widespread adoption of pulse oximetry and capnography. Reliance on indirect indicators of ventilation was often unsatisfactory, particularly in claims involving esophageal intubation. Death or permanent brain damage occurred in 85% of the respiratory related claims, contrasted with only 30% of the remaining (nonrespiratory) claims. Not surprisingly, this makes adverse respiratory events particularly costly. The reviewers determined that better monitoring would have prevented adverse outcomes in three-quarters of the respiratory claims, compared with only around 10% in the nonrespiratory cases. Both Cheney and Caplan believe that the advent of pulse oximetry and capnography has been associated with the almost complete disappearance of claims for the first two categories--inadequate ventilation and unrecognized esophageal intubation.** After the realization that difficult intubation, the third category, could largely not be prevented by better monitoring, the ASA turned its attention to developing protocols, algorithms, lectures, and videotapes to further knowledge about management of the difficult airway. The Closed Claims Project is tracking the impact of guidelines on professional liability.
Mark and her associates have vigorously promoted dissemination of critical information concerning the difficult airway. They are to be commended for helping establish the Medic Alert Foundation "Difficult Airway/Intubation" category. In addition to use of the ASA difficult airway algorithm, they recommend entry of patient data into hospital registries, use of a difficult airway/intubation patient wristband, and distribution of summary reports to healthcare providers.
There has always been a question about the percentage of human error resulting from the design of anesthesia equipment. Leslie Rendall-Baker has been a longstanding and relentless leader in this area of inquiry, particularly as it relates to the anesthesia machine and drug ampules. ,***.
Both major U.S. anesthesia machine suppliers have expended great effort to apply the latest knowledge of human factors engineering either to prevent the possibility of a human error or to prevent injury to the patient when human errors do occur. Means to prevent human error include keyed filling devices for vaporizers to prevent filling of vaporizers with the wrong agent, the diameter index safety system for gas supply hoses, and the vaporizer interlock system to prevent the simultaneous administration of two or more agents at the same time.
Fill ports at vaporizers are located so that liquid spills over before the vaporizer is overfilled. The oxygen and nitrous oxide flow control means are interlocked in such a way that the nitrous oxide flow is automatically reduced in the event that the oxygen flow is erroneously reduced to a hazardous concentration. Twenty years ago, approximately 50% of vaporizers increased the delivered concentration by a clockwise rotation of the wheel, while the other 50% increased the concentration by a counterclockwise rotation. Manufacturers agreed to standardize the vaporizer control to one direction. The most important contribution to safety in the operation of anesthesia equipment, however, is the incorporation and acceptance of monitors for oxygen, carbon dioxide, anesthetic agents, disconnects and excessive pressure, as well as other ventilatory parameters, into the anesthesia machine.
The ASA entered the world of standards writing in the mid- 1980s with Burton Epstein as Chairman of the new Committee on Standards. Since then, anesthesiologists have been lauded repeatedly by other specialties for leadership in patient safety. More recently, the ASA has moved from issuing standards to writing evidence-based guidelines for specific procedures or clinical situations, using stringent epidemiologic methodology. Once again, our efforts are attracting attention from other specialties, particularly our rigorous approach to literature analysis and consensus formation. Robert Caplan directs the scientific and procedural aspects of ASA guideline development, and James Arens is Committee Chairman.
Expansion of discussions of human error in anesthesia to the larger arena of human performance is an exciting development, exemplified by the 1991 multidisciplinary conference on human performance jointly sponsored by the APSF and the Food and Drug Administration. David Gaba has become a leader in using human performance knowledge, specifically in "breaking the chain of accident evolution," examining anesthesia mishaps along the lines of the normal accidents model in industry, as described by Perrow. [32,33]Nuclear power, aviation, and chemical systems that combine complex interaction and tight coupling are likely to have accidents despite efforts to prevent them. Simple incidents may progress to critical incidents, or further to a negative outcome. Gaba provides convincing arguments that we have much to gain from the industrial approach to accident prevention. In particular, prevention of the progression from simple to critical incidents may be enhanced by better detection of simple incidents, improving one's ability to construct and use mental maps or "overviews" of complex processes, improving backup tools for recovery from simple failures, and disseminating proper protocols for handling of rapidly propagating incidents.
How can human performance be improved? Howard Schwid provided a key insight in his studies of simulated events such as anaphylaxis and cardiac arrest. Typically, practitioners develop "fixation" errors (i.e., cognitive failure to revise a therapy plan in the face of contradictory evidence). Many investigators and educators believe that human performance can be enhanced best by the specialized training afforded by realistic simulators. Two commercial models of anesthesia simulators are available. The CAE patient simulator, designed using technologies developed separately by Gaba (Stanford) and Schwid (Seattle), is in use at Harvard, Toronto, Pittsburgh, Stanford, and Seattle. The Loral simulator, developed at Gainesville by Michael Good and associates, is functioning at Gainesville, Mount Sinai, Augusta, Hershey, Chapel Hill, Rochester, and Nashville.
Use of simulators as training devices is expanding rapidly for teaching basic anesthesia skills, for introducing crisis resource management to individual anesthesiologists and operating room teams, and for investigating the basic foundations and limitations of human performance. Time constraints will not allow me to examine in more detail human performance and patient safety as it relates to the anesthesia workstation; anesthesia resident selection; the role of sleep, fatigue, and aging; and methods for the scientific investigation of anesthesia accidents.
I call your attention to the 1995 ASA meeting scientific papers section "Patient Safety, Epidemiology, History, and Education," at which 139 papers are scheduled to be given. Ten years ago, there was not even a section on these subjects. In addition, there is a Tuesday morning panel on "Human Performance."
We should examine whether anesthesia outcomes are better today than they were 10, 20, 30, or 40 yr ago. Are J. S. Gravenstein, John Eichhorn, and Cheney correct when they say, "Yes." Let us first agree that we are anesthetizing sicker patients for more complicated surgery than in the past.
When, in 1989, John Eichhorn reviewed some 1,000,000 anesthetics administered to ASA physical status 1 and 2 patients at the various Harvard hospitals between 1976 and 1985, he noted 11 major intraoperative anesthesia accidents (2 cardiac arrests, 4 cases of severe brain damage, and 5 deaths). The most common cause (7 of 11) was an unrecognized lack of ventilation. He believed these seven as well as one other, in which oxygen was discontinued inadvertently, would have been prevented by "safety monitoring." He then noted that, of the next 300,000 anesthetics after the institution of the Harvard monitoring standards in 1985, there were no major preventable intraoperative anesthesia injuries. He concluded that this was a considerable improvement in outcome related to the institution of monitoring with capnography and pulse oximetry.
In an accompanying editorial, Fred Orkin conceded that "the death rate related primarily or solely to anesthesia care has decreased markedly during the past four decades. . . ." His principal concern was "that we have yet to learn the true benefits and risks of newer monitoring equipment. . . . The critical need is to learn more about the relationship between what we do and patient outcome." Practice standards "must be shown to produce a net benefit before [they become]. . .part of clinical practice."
Others disagree with Keats and Orkin. Among them is J.S. Gravenstein, who says, in essence, that it is important to recognize that many changes (not to call them advances) in medicine have been introduced without the benefit of controlled scientific studies. ,**** Their impact on the quality of care or outcome cannot be measured. However, in the absence of measurable effects, we cannot conclude that there are no effects, especially good effects. So much in medicine over the years has not been measurable. Who, for example, in anesthesia would use high spinal anesthesia to anesthetize a patient in hypovolemic shock. We have had no scientific prospective studies to prove that is harmful. Is it always necessary to insist on rigorous scientific proof for each and every aspect of care?
No, we cannot prove in a scientific manner that anesthesia is safer today, although I believe that most anesthesiologists who practiced years ago will eagerly agree that it is. Moreover, it is unlikely that funds ever will be available to do definitive prospective outcome studies. Beginning in the early 1980s, anesthesiologists in New Jersey, California, and Arizona worked closely with their insurance companies. I continue to argue that the significant decreases in relativity factors for anesthesia medical liability premiums are due to the marked decline in the severe anesthesia negative outcomes--death and permanent brain damage. Certainly the insurance industry concurs. Let us look once again at the figures. At Harvard, the current relativity is 2.5 instead of 5.0, as it was in 1985 (Table 5and Table 6). Hence the current premium is $10,000 instead of the $20,000 it would be if the relativity were still 5.0. If each of us saves $10,000 per year in insurance premiums (as at Harvard), that is $300,000,000 for the entire country. However, as I have said repeatedly (and I often choke up when making this comment), the overall incidence of anesthesia mortality is not important when the death due to an unrecognized esophageal intubation is in your own 18-yr-old child undergoing odontectomy. In the last year or so I have heard of several accidents resulting in death or severe brain damage--probably due to errors on the part of the anesthesiologists.
As this lecture nears its end, I would like to offer a general observation and some advice for the future. Patient safety is not a fad. It is not a preoccupation of the past. It is not an objective that has been fulfilled or a reflection of a problem that has been solved. Patient safety is an ongoing necessity. It must be sustained by research, training, and daily application in the workplace.
I fear that we may be entering an era that could easily undo many of the gains that we cherish so highly. This is the era of cost-containment, production-pressure, and bottom-line decision-making by corporate deal-makers. The forces underlying this new era are driving us to be leaner, faster, and cheaper. To some extent, these changes may bring a measure of immediate health and vigor to the practice of medicine; they also pose a worrisome threat. If we try to meet financial challenges by short-cutting our daily attention to patient safety or by minimizing our long-term commitments to education and research, we may not be able to carry forward the gains of the immediate past or pursue the exciting insights and innovations that are just emerging. As Nik Gravenstein said so succinctly in the most recent issue of the APSF Newsletter, "We must raise our voices in support of safety.***** If we do not, safety will take a backseat to economy."
My friends and colleagues, our efforts to improve the safety of anesthesia have merely begun. Significant challenges await us, perhaps more so in the coming years than in the past four decades that I have had the pleasure and privilege to describe to you. But we must not retreat; we must not lose our collective resolve. Patient safety is truly the framework of modern anesthetic practice, and we must redouble efforts to keep it strong and growing.
*Cheney FW: ASA closed claims project--where have we been and where are we going? American Society of Anesthesiologists Newsletter 1993;57:8-22.
**Cheney FW, Caplan RA: Personal communication. 1995.
***Rendell-Baker L: Better labels will cut drug errors. Anesthesia Patient Safety Foundation Newsletter 1987;2:29-32.
****Gravenstein JS: Personal communication. 1995.
*****Gravenstein JS: Will "cost containment" decrease safety? Anesthesia Patient Safety Foundation Newsletter 1995; 10:25-9.