Arnold J. Berry
Jonathan D. Katz
1. With the use of scavenging equipment, routine machine maintenance, and appropriate work practices, exposure to waste anesthetic gases can be reduced to levels below those recommended by National Institute for Occupational Safety and Health (NIOSH).
2. Twenty-four percent of anesthesia personnel manifest evidence of contact dermatitis in response to latex exposure and approximately 15% are sensitized and vulnerable to allergic reactions.
3. Vigilance is one of the most critical tasks performed by anesthesiologists. The vigilance task is adversely affected by several factors including poor equipment engineering and design, excessive noise in the operating room, impediments to interpersonal communication, production pressure, and fatigue.
4. Sleep deprivation and fatigue are common among anesthesiologists. Sleep deprivation can have deleterious effects on cognition, performance, mood, and health.
5. The risk of exposure to infectious pathogens can be reduced by the routine use of standard precautions, transmission-based precautions for infected patients, and safety devices designed to prevent needlestick injuries.
6. Hepatitis B vaccine is recommended for all anesthesia personnel because of the increased risk for occupational transmission of this blood-borne pathogen.
7. Many consider chemical dependency to be the primary occupational hazard among anesthesiologists. An incidence of 1 to 2% of controlled substance abuse has been repeatedly reported within anesthesia training programs.
8. It remains controversial whether anesthesiologists are, on average, vulnerable to premature death. However, by correcting for the fact that living anesthesiologists are, on average, younger than most other specialists, it is apparent that anesthesiologists do not die younger.
Anesthesia personnel spend long hours, in fact, most of their waking days, in an environment filled with many potential hazards—the operating room. This setting is unique among workplaces as a result of the potential exposure to chemical vapors, ionizing radiation, and infectious agents. Additionally, anesthesia personnel are subject to heightened levels of psychological stress engendered by the high-stakes nature of the practice and the long periods of sustained time on duty. Although such physical hazards as fires and explosions from flammable anesthetic agents are currently of limited concern, occupational illnesses, such as alcohol and drug abuse, are well recognized as significant within the anesthesia community. Some hazards, such as exposure to trace levels of waste anesthetic gases, have been extensively studied. Others, like suicide, have been recognized but not adequately pursued. Only within the past few decades have epidemiologic surveys been conducted to assess the health of anesthesia personnel. In general, the potential health risks to those working in the operating room may be significant, but with awareness of the problems and the use of proper precautions, they are not formidable.
Although the inhalation anesthetics diethyl ether, nitrous oxide, and chloroform were first used in the 1840s, the biologic effects of occupational exposure to anesthetic agents were not investigated until the 1960s. Reports on the effects of chronic environmental exposure to anesthetics have included epidemiologic surveys, in vitro studies, cellular research, and studies in laboratory animals and humans. Areas addressed include the potential influence of trace anesthetic concentrations on the incidence in affected populations of the following: death, infertility, spontaneous abortion, congenital malformations, cancer, hematopoietic diseases, liver disease, neurologic disease, psychomotor, and behavioral changes.
Anesthetic Levels in the Operating Room
The first report of occupational exposure to modern anesthetics was by Linde and Bruce in 1969.1 They sampled air at various distances from the “pop-off” valve of anesthesia machines and noted an average concentration of halothane of 10 parts per million (ppm) and of nitrous oxide of 130 ppm. (Parts per million is a volume-per-volume unit of measurement; 10,000 ppm equals 1%.) End-expired air samples taken from 24 anesthesiologists after work revealed 0 to 12 ppm of halothane. It was later demonstrated that with appropriate scavenging equipment integrated with the anesthesia breathing circuit and with adequate air exchange in the operating room, levels of waste anesthetic gases could be significantly reduced.
Waste anesthetic concentrations in modern operating rooms where routine scavenging is performed are considerably less than those found in the early studies.2,3 This raises the questions of whether chronic exposure to these low levels of waste anesthetic gases actually constitutes a significant occupational hazard and whether results from studies performed in “unscavenged” operating rooms are applicable to current practice.
Epidemiologic surveys were among the first studies to suggest the possibility of a hazard resulting from exposure to trace levels of anesthetics. Although epidemiologic studies may be useful in assessing problems of this type, they have the potential for errors associated with the collection of data and their interpretation. Valid epidemiologic studies require appropriate design strategies including the presence of an appropriate control group for the cohort being studied. When questionnaires are used to obtain personal medical information, the data may be misleading because individuals may knowingly or unknowingly give incorrect information based solely on remembered data (recall bias). Cause-and-effect relationships or causality cannot be documented by epidemiologic observational studies unless all other possible etiologies (confounders) can be ruled out or other lines of evidence are used for substantiation. Few epidemiologic studies on the effects of occupational exposure to waste anesthetic gases fulfill these design criteria.
One of the largest epidemiologic studies to assess the effects of trace anesthetics on reproductive outcome was conducted by the American Society of Anesthesiologists (ASA).4Questionnaires were sent to 49,585 operating room personnel who had potential exposure to waste anesthetic gases (members of the ASA, the American Association of Nurse Anesthetists, the Association of Operating Room Nurses, and the Association of Operating Room Technicians). A nonexposed group of 23,911 from the American Academy of Pediatrics and the American Nurses' Association served as controls. Analyses of these data indicated that there was an increased risk of spontaneous abortion and congenital abnormalities in children of women who worked in the operating room and an increased risk of congenital abnormalities in offspring of unexposed wives of male operating room personnel. Several reviews have identified inconsistencies in the data used to compare exposed and unexposed groups and to make within-group comparisons. Expected levels of anesthetic exposure did not correlate with reproductive outcome.
The ASA subsequently commissioned a group of epidemiologists and biostatisticians to evaluate and assess conflicting data from published epidemiologic surveys.5 After analysis of methods, they found only five studies on spontaneous abortion and congenital abnormalities in offspring of anesthesia personnel that were free of errors in study design or statistical analysis. From these studies, the relative risks (the ratio of the rate of disease among those exposed to that found in those not exposed) of spontaneous abortion for female physicians and female nurses working in the operating room were 1.4 and 1.3, respectively (a relative risk of 1.3 represents a 30% increase in risk when compared with the risk of the control population). The increased relative risk for congenital abnormalities was of borderline statistical significance for exposed physicians only. Although they found a statistically significant relative risk of spontaneous abortion and congenital abnormalities in women working in the operating room, the relative risk was small compared with other, better-documented environmental hazards. They also pointed out that duration and level of anesthetic exposure were not measured in any of the studies and that other confounding factors, such as stress, infections, and radiation exposure, were not considered as confounders.
Because personnel working in some dental operatories have exposure to nitrous oxide, the dental literature has also addressed these issues. One pertinent study used data collected via telephone interviews with 418 female dental assistants to assess the effect of nitrous oxide exposure on fertility.6 Fecundability (the ability to conceive) was significantly reduced in women with 5 or more hours of exposure to unscavenged nitrous oxide per week. In another study of 7,000 female dental assistants, questionnaires were used to determine rates of spontaneous abortion.7 There was an increased rate of spontaneous abortion among women who worked for 3 or more hours per week in offices not using scavenging devices for nitrous oxide (relative risk [RR] = 2.6, adjusted for age, smoking, and number of amalgams prepared per week). These findings must be viewed with caution because the estimates of nitrous oxide exposure were based solely on respondents' reports, and measurements of nitrous oxide concentrations in the work space were not performed. Therefore, dose-effect relationships cannot be confirmed. It is important to note that in both studies of female dental assistants, use of nitrous oxide in offices with scavenging devices was not associated with an increased risk for adverse reproductive outcomes.6,7
A meta-analysis of 19 epidemiologic studies, which included hospital workers, dental assistants, and veterinarians and veterinary assistants, demonstrated an increased risk of spontaneous abortion in women with occupational exposure to anesthetic gases (RR = 1.48; 95% confidence interval, 1.40 to 1.58).8 Additional analysis demonstrated that the relative risk of 1.48 corresponded to an increased absolute risk of abortion of 6.2%. Stratification by job category indicated that the relative risk was greatest for veterinarians (RR = 2.45), followed
by dental assistants (RR = 1.89) and hospital workers (RR = 1.30). When the meta-analysis was confined to five studies that controlled for several nonoccupational confounding variables, had appropriate control groups, and had sufficient response rate, the relative risk for spontaneous abortion was 1.90 (95% confidence interval, 1.72 to 2.09). The author noted that the routine use of scavenging devices has been implemented since the time that most of the studies in this analysis were performed and that there was no risk of spontaneous abortion in studies of personnel who worked in scavenged environments.
Retrospective surveys of large numbers of women who worked during pregnancy indicate that adverse reproductive outcomes may be related to job-associated conditions other than exposure to trace anesthetic gases. A survey of 3,985 Swedish midwives demonstrated that night work was significantly associated with spontaneous abortions after the 12th week of pregnancy (odds ratio = 3.33), while exposure to nitrous oxide appeared to have no effect.9 Using a case-control study design, Luke et al10 found that increased work hours, hours worked while standing, and occupational fatigue were associated with preterm birth in obstetric and neonatal nurses. These and other studies have provided data that link spontaneous abortion in women working in health care to job-related factors other than exposure to trace anesthetic gases. This casts doubt on the validity of earlier studies that did not control for occupational stresses such as fatigue, long work hours, and night shifts.
Although many of the existing epidemiologic studies have potential flaws in design, the evidence taken as a whole suggests that there is a slight increase in the relative risk of spontaneous abortion and congenital abnormalities in offspring for female physicians working in the operating room.11 Whether these findings are attributable to anesthetic exposure or other work-related conditions cannot be definitely determined from this type of investigation. Well-designed surveys of large numbers of personnel and appropriate control groups, controlled for other factors such as work hours and night shifts, are necessary to link trace anesthetic exposures to adverse reproductive outcomes. The routine use of scavenging techniques has generally lowered environmental anesthetic levels in the operating room and may make it more difficult to prove any adverse reproductive effects using epidemiologic data. Although it is easy to measure and quantify the levels of anesthetic in the operating room air, it is harder to measure and assess the effect of other possible factors, such as stress, alterations in working schedule, and fatigue.
Neoplasms and Other Nonreproductive Diseases
Early surveys enumerating causes of death among anesthesiologists indicated that male anesthesiologists had a greater risk of malignancies of the lymphoid and reticuloendothelial tissues and from suicide, but a lower death rate from lung cancer and coronary artery disease.12 Data from a subsequent prospective study provided no evidence to support the previous conclusion that lymphoid malignancies were an occupational hazard for anesthesiologists.13
An ASA-sponsored study, published in 1974, found no differences in cancer rates between men exposed and those not exposed to trace concentrations of anesthetic gases.4 For women respondents, there was a 1.3-fold to 2-fold increase in the occurrence of cancer in the exposed group, resulting predominantly from an increase in leukemia and lymphoma. The analysis of Buring et al5 of these data confirmed an increase in relative risk of cancer in exposed women (RR = 1.4) but attributed the increase solely to cervical cancer (RR = 2.8). They also noted that the ASA study did not assess the effect of confounding variables, such as sexual history or smoking, that may have contributed to the findings. It is doubtful that the carcinogenic effect of anesthetics would be sex-related, and the conflicting results for men and women, especially in light of the low statistical significance of the data, cast doubt that anesthetics were the causative agents.
Another ASA-sponsored mortality study of anesthesiologists, covering the period from 1976 to 1995, used data on cause of death from the National Death Index.14 The mortality risks of a cohort of 40,242 anesthesiologists were compared with a matched cohort of internists. There was no difference between the two groups in overall mortality risk or mortality from cancer or heart disease, but the mean age at death was significantly lower for anesthesiologists compared with internists (66.5 years vs. 69.0 years). In a subsequent study, Katz15used data from the American Medical Association (AMA) to conclude that there was no statistical difference in age-specific mortality among anesthesiologists, internists, and other physicians when ages of the living members of the physician groups were considered in the analyses.
Epidemiologic observational studies are useful tools for attempting to identify adverse effects of the operating room environment, including exposure to many substances, of which waste anesthetic gases comprise but one factor. The data from observational surveys can, at best, identify associations but can never prove cause-and-effect relationships between an exposure to a condition or substance and a disease process. Many surveys that attempt to assess the effects of waste anesthetic gases have method design flaws such as failure to control for possible confounding factors, and these have resulted in conflicting conclusions. Overall, there appears to be some evidence that the operating room environment produces a slight increase in the rate of spontaneous abortion and cancer in female anesthesiologists and nurses.5 Mortality risks from cancer and heart disease for anesthesiologists do not differ from those for other medical specialists.
Along with epidemiologic studies, investigators have been active in the laboratory, assessing the effects of anesthetic agents on cell, tissue, and animal models. It is thought that this work might provide the scientific evidence linking anesthetic exposure to the adverse effects that have been suggested by some observational studies.
Nitrous oxide administered in clinically useful concentrations affects hematopoietic and neural cells by irreversibly oxidizing the cobalt atom of vitamin B12 from an active to inactive state. This inhibits methionine synthetase and prevents the conversion of methyltetrahydrofolate to tetrahydrofolate, which is required for DNA synthesis, assembly of the myelin sheath, and methyl substitutions in neurotransmitters. Inhibition of methionine synthetase in individuals exposed to high concentrations of nitrous oxide may result in anemia and polyneuropathy, but chronic exposure to trace levels found in scavenged operating rooms does not appear to produce these effects.
Many studies have been performed in animals to assess the carcinogenicity of anesthetics. Because of the extreme variability of study protocols, use of animals of differing species, and failure to consider possible confounders in study design, a definitive link between anesthetics and cancer has not been proven.
Several investigators have used the Ames bacterial assay system for studying the mutagenicity of anesthetics. This assay is rapid, inexpensive, and has a high true-positive rate when compared with in vivo tests. Halothane, enflurane, methoxyflurane, isoflurane, sevoflurane and urine from patients
anesthetized with these agents was not mutagenic using this assay. Urine from people working in scavenged or unscavenged operating rooms was also negative for mutagens.
Other studies have used analyses of sister chromatid exchanges or formation of micronucleated lymphocytes to assess for genotoxicity in association with anesthetic exposure. These tests may be of interest because there may be an association between these genetic changes and cancer. The majority of studies using sister chromatid exchange testing have been negative for enflurane, isoflurane, and sevoflurane exposure.16
Anesthetists at an institution where waste gas scavenging was not used had an increased fraction of micronucleated lymphocytes compared with those practicing in a hospital where waste anesthetic gases were scavenged.17 Low-level exposure as occurs in scavenged operating rooms was not associated with increased formation of micronucleated lymphocytes. The predictive value for the association of this test to the incidence of cancer is unclear.
The data from several lines of evidence indicate that occupational exposure to the low levels of anesthetics found with effective waste gas scavenging is not associated with significant cellular effects.
Because of the suggestion from epidemiologic data that occupational exposure to waste anesthetic gases may have resulted in an increased rate of spontaneous abortion and congenital abnormalities, numerous studies have been performed in laboratory animals to assess reproductive outcome. Most animal experiments fail to demonstrate alterations in female or male fertility or reproductive outcome with exposure to the subanesthetic concentrations of the currently used anesthetic agents achievable with scavenging and appropriate work practices. It is important to realize that data from laboratory investigations in animals may not be directly applicable to humans.
Effects of Trace Anesthetic Levels on Psychomotor Skills
Several studies have been conducted to attempt to clarify whether low concentrations of anesthetics alter the psychomotor skills required for providing high-quality care. In one investigation, psychomotor tests were used to assess the effect of nitrous oxide (500, 50, or 25 ppm) alone or with halothane (10, 1.0, or 0.5 ppm).18 After exposure to the highest concentrations of nitrous oxide and halothane, subjects' performance declined on four of the seven tests. Interestingly, there was a decrease in ability in six of seven tests after exposure to the same level of nitrous oxide alone. Exposure to the lowest concentrations studied, 25 ppm nitrous oxide and 0.5 ppm halothane, produced no effects as measured by this battery of tests.
Other investigators using similar protocols have found no effect on psychomotor test performance after exposure to trace concentrations of halothane or nitrous oxide. The reason for differences in outcome between studies is unclear, but Bruce and Stanley,19 among the original investigators, have attributed the psychological effects of low levels of anesthetics to unusual sensitivity in the group of paid volunteers used in the study.
Recommendations of the National Institute for Occupational Safety and Health
The National Institute for Occupational Safety and Health (NIOSH) is the federal agency responsible for ensuring that workers have a safe and healthful working environment. It meets these goals through the conduct and funding of research, through education of employers and employees about occupational illnesses, and through establishing occupational health standards. A second federal agency, the Occupational Safety and Health Administration (OSHA), is responsible for enacting job health standards, investigating work sites to detect violation of standards, and enforcing the standards by citing violators. In 1977, NIOSH published a criteria document that included recommended exposure limits (REL) for waste anesthetic gases of 2 ppm (1-hour ceiling) for halogenated anesthetic agents (halothane, enflurane) when used alone or 0.5 ppm of a halogenated agent and 25 ppm of nitrous oxide (time-weighted average during the period of anesthetic administration).20 In addition, it stated that operating room employees should be advised of the potential harmful effects of anesthetics. The guidelines proposed that annual medical and occupational histories be obtained from all personnel and that any abnormal outcomes of pregnancies should be documented. The publication also included information on scavenging procedures and equipment and methods for monitoring concentrations of waste anesthetic gases in the air.
The 1977 NIOSH criteria document has not been adopted by OSHA, which has not set a standard permissible exposure limit for waste anesthetic gases. Some states, however, have instituted regulations calling for routine measurement of ambient nitrous oxide in operating rooms and have mandated that levels not exceed an arbitrary maximum. In 1994, NIOSH published an alert to warn health care personnel that exposure to nitrous oxide may produce “harmful effects.”21 In this document, NIOSH recommends the following to reduce nitrous oxide exposure: (1) monitoring the air in operating rooms; (2) implementation of appropriate engineering controls, work practices, and equipment maintenance procedures; and (3) institution of a worker education program.
NIOSH has not developed RELs for the agents most commonly used in current practice (isoflurane, sevoflurane, and desflurane). These volatile agents have potencies, chemical characteristics, and rates and products of metabolism that differ significantly from older anesthetics. In 2006, NIOSH issued a request for information to permit the agency to evaluate possible health risks of occupational exposure to isoflurane, sevoflurane, and desflurane and to establish RELs.
It is important to note that other organizations both in and outside the United States have set occupational exposure limits for waste anesthetic gases and, in most cases, these are greater than those recommended by NIOSH. For example, the American Conference of Governmental Industrial Hygienists has recommended a threshold limit value–time-weighted average (calculated for an 8-hour shift) for nitrous oxide of 50 ppm, for enflurane of 75 ppm, and for halothane of 50 ppm.
In view of the conflicting scientific data and published recommendations, it is reasonable to ask what is an acceptable exposure level for waste anesthetic gases. Although it may be difficult to be certain of a threshold concentration below which chronic exposure is “safe,” it is prudent to institute measures that reduce waste anesthetic levels in the operating room environment to as low as possible without compromising patient safety.
Methods for reducing and monitoring waste gases in the operating room have been suggested.3,21 Through the use of scavenging equipment, equipment maintenance procedures, appropriate anesthetic work practices, and efficient operating room ventilation systems, the environmental anesthetic concentration can be reduced to minimal levels. To ensure reduced occupational exposure, departmental programs should incorporate the ability to monitor for detection of leaks in the high-and low-pressure systems of anesthetic machines, contamination as a result of faulty anesthetic techniques such as poor mask fit or leaks around the cuffs of endotracheal tubes and
laryngeal mask airways, and scavenging system malfunctions (Table 3-1). When there have been leaks of anesthetic gases, dispersion and removal of the pollutants depend on the adequacy of room ventilation. Standards for operating room construction from the American Institute of Architects require 15 to 21 air exchanges per hour with 3 bringing in outside air.22 Environmental levels of anesthetics can be measured using instantaneously collected samples, continuous air monitoring, or time-weighted averages.3 With appropriate care, environmental levels of anesthetics in the operating room can be reduced to comply with the RELs established by NIOSH.
Table 3-1 Sources of Operating Room Contamination
Anesthetic Levels in the Postanesthesia Care Unit
Patients who have received volatile anesthetics release these gases into the environment as they awaken from general anesthesia in the postanesthesia care unit (PACU). In a 1998 study, the time-weighted average concentrations for isoflurane, desflurane, and nitrous oxide were 1.1 ppm, 2.1 ppm, and 29 ppm, respectively, in the breathing zone of PACU nurses.23 Half of the patients were intubated on arrival in the PACU, suggesting that they were still partially anesthetized and were exhaling a greater concentration of anesthetic gases than if they had already awakened. In contrast, other investigators reported time-weighted nitrous oxide levels <2.0 ppm from two PACUs.24 The practice in these institutions was to routinely discontinue nitrous oxide at the end of surgery, approximately 5 minutes before the patient left the operating room. Also, there was adequate air exchange documented in the PACUs. NIOSH threshold limits for anesthetic gases can be obtained in the PACU by ensuring adequate room ventilation and fresh gas exchange and by discontinuing the anesthetic gases in sufficient time prior to leaving the operating room.
Methyl methacrylate is commonly used to cement prostheses to bone or to repair bone defects. Known cardiovascular complications of methyl methacrylate in surgical patients include hypotension, bradycardia, and cardiac arrest. The effects of occupational exposure are less well documented. Reported risks from repeated occupational exposure to methyl methacrylate include skin irritation and burns, allergic reactions and asthma, eye irritation including possible corneal ulceration, headache, and neurologic signs. Airborne concentrations greater than 170 ppm have been associated with chronic lung, liver, and kidney damage. In one report, a health care worker (HCW) suffered significant lower limb neuropathy after repeated occupational exposure to methyl methacrylate.25 OSHA has established an 8-hour, time-weighted average allowable exposure of 100 ppm. Concentrations as high as 280 ppm have been measured when methyl methacrylate is prepared for use in the operating room, but peak environmental
concentration can be decreased by 75% when scavenging devices are properly used.
In addition to concerns about toxic effects associated with exposure to volatile anesthetics or chemicals, anesthesiologists may develop sensitivities or allergic reactions to substances found in the health care environment.
Allergic reactions to volatile anesthetic agents have been associated with contact dermatitis, hepatitis, and anaphylaxis in individual anesthesiologists.26,27 Analyses of sera from pediatric and general anesthesiologists demonstrated that exposure to halothane was associated with an increased prevalence of autoantibodies to cytochrome P450 2E1 and hepatic endoplasmic reticulum protein (ERp58).28 Despite the presence of these autoantibodies, only 1 of 105 pediatric anesthesiologists had symptoms of hepatic injury. These data suggest that although autoantibodies may occur in anesthesiologists exposed to volatile anesthetics, they do not appear to be the cause of anesthetic-induced hepatitis.
Latex in surgical and examination gloves has become a common source of allergic reactions among operating room personnel. In many cases, HCWs who are allergic to latex experience their first adverse reactions while they are patients undergoing surgery. The prevalence of latex sensitivity among anesthesiologists is approximately 15%.29,30
The latex found in medical products is actually a composite of many substances including proteins, polyisoprenes, lipids and phospholipids combined with preservatives, accelerators, antioxidants, vulcanizing compounds, and lubricating agents (such as cornstarch or talc). The protein content is responsible for most of the generalized allergic reactions to latex-containing surgical gloves. These reactions are exacerbated by the presence of powder that enhances the potential of latex particles to aerosolize and to spread to the respiratory system of personnel and to environmental surfaces during the donning or removal of gloves.
Table 3-2 Types of Reactions to Latex Gloves
Irritant or contact dermatitis accounts for the majority of reactions resulting from wearing latex-containing gloves. (Table 3-2). True allergic reactions present as T-cell–mediated contact dermatitis (type IV) or as an immunoglobulin E-mediated anaphylactic reaction.
Anesthesiologists who believe that they are allergic to latex should take immediate steps to assess this possibility.31 If a diagnosis of allergy has been established, the affected anesthesiologist must avoid all direct contact with latex-containing products. It is also important that coworkers wear nonlatex or powderless, low latex-allergen gloves to limit the levels of ambient allergens. Because sensitization is an irreversible process, limited exposure and primary prevention of allergy is the best overall strategy. Anaphylactic reactions to latex can be life-threatening.
Many modern surgical procedures rely heavily on fluoroscopic guidance techniques. As a result, anesthesiologists are at risk for being exposed to excessive radiation. The magnitude of radiation absorbed by individuals is a function of three variables: (1) total radiation exposure intensity and time, (2) distance from the source of radiation, and (3) the use of radiation shielding. The latter two are amenable to modification by the
anesthesiologist. Unfortunately, the lead aprons and thyroid collars commonly worn leave exposed many vulnerable sites, such as the long bones of the extremities, the cranium, the skin of the face, and the eyes. Because radiation exposure is inversely proportional to the square of the distance from the source, increasing this distance is more universally protective. Radiation exposure becomes minimal at a distance greater than 36 inches from the source, a distance that is easily attainable in most anesthetizing locations.
The U.S. Regulatory Commission has established an occupational exposure limit of 5,000 mrem/year. Occupational exposures among anesthesia personnel have been reported to be considerably below this limit.32 However, these studies were conducted before the introduction of many of the modern surgical procedures that rely heavily on fluoroscopic guidance techniques. A more recent study reported a doubling of the aggregate radiation exposure to the members of a department of anesthesiology in the year following the introduction of an electrophysiology laboratory.33 Pregnant workers present special concerns, and the dose to the fetus should be <500 mrem during the gestation period.
Oncogenesis, teratogenesis, and long-term genetic defects can occur with sufficiently high exposure to radiation. The risks associated with radiation vary considerably, depending on age, gender, and specific organ site exposure.34 However, even low levels of radiation exposure are not inconsequential. The stochastic biologic effects of radiation are cumulative and permanent.a There are no published data that define the lower threshold for radiation-induced disease. Therefore, the general admonition regarding occupational radiation exposure, and the basis of protection programs, is as low as reasonably achievable.
Noise pollution is a potential health hazard that is virtually uncontrolled in the modern hospital and specifically in the operating room. Noise is quantified by determining both the intensity of the sound in decibels (dB) and the duration of the exposure. NIOSH has determined that the maximum level for safe noise exposure is 90 dB for 8 hours.35 Each increase in noise of 5 dB halves the permissible exposure time, so that 100 dB is acceptable for just 2 hours per day. The maximum allowable exposure in an industrial setting is 115 dB.
The noise level in many operating rooms is surprisingly close to what constitutes a health hazard.36 Ventilators, suction equipment, music, and conversation produce background noise at a level of 75 to 90 dB. Superimposed on this are sporadic and unexpected noises caused by dropped equipment, surgical saws and drills, and monitor alarms. Resultant noise levels frequently exceed 120 dB and are comparable to the clamor of a busy freeway.37
Excessive levels of noise can have an adverse influence on the anesthesiologist's capacity to perform clinical tasks. Noise can interfere with the ability to discern conversational speech and to hear auditory alarms. Mental efficiency and short-term memory are diminished by exposure to excess noise.36 Complex psychomotor tasks associated with anesthesiology, such as monitoring and vigilance, are particularly sensitive to the adverse influences of noise pollution.
There are also chronic ramifications of long-term exposure to excessive noise in the workplace. At the very least, noise pollution is an important factor in decreased worker productivity. At higher noise levels, workers are likely to show signs of irritability and demonstrate evidence of stress, such as elevated blood pressure. Ultimately, hearing loss may ensue.38
Figure 3-1. Official seal of the American Society of Anesthesiologists. “VIGILANCE” has always been recognized as the most critical of the anesthesiologist's tasks.
On the other hand, one form of background noise, music, can provide a number of beneficial effects. Music has proved advantageous as a supplement to sedation and analgesia for surgical patients.39,40 Self-selected background music can contribute to reducing autonomic responses in surgeons and improving their performance.41 The beneficial effects are less pronounced when the music is chosen by a third party. The selection of music, and the volume at which it is played, should be by mutual agreement of all parties present in the operating room.
The work performed by an anesthesiologist can be intricate and includes a number of complex tasks. Extensive research and marketing efforts have been directed toward finding high-technology solutions to assist the anesthesiologist in managing this demanding workload. Less attention has been given to applying human factor technology to improve the workplace and ensure patient safety. Human error has been identified as a significant cause of patient morbidity and mortality.42
A number of human factor difficulties potentially exist in the operating room. For example, anesthesia equipment is often poorly designed or positioned. Anesthesia monitors and record-keeping equipment are frequently placed so that attention must be directed away from the patient and surgical field. This was well demonstrated by observations that the insertion and monitoring of a transesophageal echocardiograph added significantly to the anesthesiologist's workload and diverted attention away from other patient-specific tasks.43
The ability to respond to critical incidents and to sustain complex monitoring tasks, such as maintaining vigilanceb are among those tasks that are most vulnerable to the distractions created by poor equipment design or placement. The critical importance of the vigilance task to the practice of anesthesiology is evidenced by the fact that the seal of the ASA bears as its only motto, “Vigilance” (Fig. 3-1).
Several aspects of the vigilance task deserve attention. This function is repetitive and monotonous. The task does not fully occupy the anesthesiologist's mental activity, but neither does it leave him or her free to perform other mental functions. Finally, the task is complex, requiring visual attention as well as manual dexterity.
Vigilance tasks are generally performed at the level of 90% accuracy.44 In a setting where the stakes are high, such as during anesthesia, this leaves an unacceptable margin of error. In fact, human error, in part resulting from lapses in attention, accounts for a large proportion of the preventable deaths and serious injuries resulting from anesthetic mishaps in the United States annually.
In addition to poor equipment design, a number of other factors conspire to hamper the ability of the anesthesiologist to perform multiple complex tasks. Any factor that requires the expenditure of excessive energy to perform a given task produces a predictable decrement in performance. Even the most trivial aspect of an operator's performance plays a significant role over the course of time. For example, if the anesthesiologist must make frequent rapid changes in observation from a dim, distant screen to a bright, nearby one, the continuous muscular activity required for pupil dilation and constriction and lens accommodation promotes fatigue and hinders performance.
The detrimental effects of unnecessary energy expenditure can be mental as well as physical. As more functions are monitored and more data processed during the course of a surgical procedure, increasingly larger amounts of mental work are expended. The mental work varies directly with the difficulty encountered in extracting information from the monitors and displays competing for the anesthesiologist's attention. Poor engineering of the monitor displays, so that mode of presentation, signal frequency, or strength is suboptimal, can adversely influence the operator's performance.
Even the alarms that have been developed with the specific goal of supplementing the task of vigilance can have considerable drawbacks. In general, alarms are nonspecific (the same alarm signaling as many as 12 different deviations from “normal”) and can be a source of frustration and confusion. They are frequently susceptible to artifacts and frequent false-positive alarms that can distract the observer from more clinically significant information. It is not unusual for frequently distractive alarms to be inactivated. In 2005, the ASA revised its Standards for Basic Monitoring to mandate that pulse oximeter and capnography alarms should not be turned off.c
Noise can have a detrimental influence on the anesthesiologist working at multiple tasks. The average noise level of 77 decibels found in operating rooms can reduce mental efficiency and short-term memory. In general, obtrusive noises, such as loud talking, excessive clanging of instruments, and “broadband” noise, are associated with decrements in performance.
Organizational issues, such as failed communication among team members, can have a detrimental effect on an anesthesiologist's performance. The potential for disaster as a result of poor communication has been well illustrated in a number of airline catastrophes.45 The possibility for miscommunication and resultant accident is heightened in the operating room where, in contrast to the structure inherent in an airline crew, there is an absence of a well-defined hierarchical organization and there are overlaps in areas of expertise and responsibility. Poor communication can lead to conflict, compromised patient safety,46 and has been identified as a root cause of 35% of anesthesia-related sentinel events.47
Effective conflict resolution is an important element of the team work necessary for successful surgical outcomes. Conflict and unpleasant interpersonal interactions among team members are among the most stressful aspects of the job of an anesthesiologist and can hinder safe anesthetic care.48 Conflict occurs during the management of as many as 78% of patients in high-intensity areas such as operating rooms or critical care units.49
Successful resolution of conflict is a skill that can be learned.50 The airline industry has successfully implemented crew resource management programs to improve the performance of cockpit teams.51 Fundamentally, mutual respect is required among team members along with a willingness to carefully listen and recognize the differences of opinion. Intervention by a neutral third party is frequently helpful in finding an innovative solution.52
“Production pressure” is an organizational concern that has the potential to create an environment in which issues of productivity supersede those of safety.53 Production pressure has been associated with the commission of errors resulting from haste and/or deliberate deviations from known safe practices.
The application of simulation technology is gaining acceptance as a tool to study and teach human performance issues in anesthesiology.54 It appears to be particularly suited to training nontechnical skills such as resource management, teamwork, and communication.55
Work Hours and Night Call
Prolonged work hours that result in sleep deprivation and fatigue are a ubiquitous component of many anesthesiologists' professional lives. Ten- to 12-hour workdays are common. Additional emergency and on-call coverage frequently result in 24- to 32-hour shifts. Gravenstein et al56 reported the average anesthesiologist's work week was 56 hours. Seventy-four percent of the study respondents reported that they had worked without a break for longer periods than they personally thought was safe and 64% attributed an error in anesthetic management to fatigue. Howard et al57 demonstrated that residents in their routine, non–postcall state suffered from chronic sleep deprivation and had the same degree of sleepiness as measured in residents finishing 24 hours of in-house call.
Long hours of work and night call are especially challenging for the aging anesthesiologist. Older individuals are particularly sensitive to disturbances of the sleep–wake cycle and are in general better suited to phase advances (morning work) than phase delays (nocturnal work).58 Demands associated with night call have been identified as the most stressful aspect of practice and most frequently cited impetus toward retirement.58
Sleep deprivation and circadian disruption have deleterious effects on cognition, performance, mood, and health.59 Both acute sleep loss (24 hours of on-call duty) and chronic partial sleep deprivation (<6 hours of sleep per night) result in a similar degree of neurobehavioral impairment. The nature and degree of impairment on psychomotor testing with acute sleep deprivation bears a striking similarity to that seen with alcohol intoxication.60
The deleterious effect of sleep loss and fatigue on work efficiency and accuracy is well documented in many industries.54,61 Sleep deprivation has been implicated as a contributing factor in many well-publicized industrial accidents such as those that occurred at Chernobyl and Three Mile Island. Data collected from residents in many clinical settings demonstrate that work shifts of greater than 24 hours are associated with an increased risk of attentional failures, significant medical errors, and adverse patient events.62 Other studies indicate that residents working extended duration shifts
had an increased risk of percutaneous injuries and were more likely to report motor vehicle crashes or near-miss incidents during their commute from work.
Complex cognitive tasks that are specific to anesthesiology, such as monitoring and accurate clinical decision-making, may be adversely affected by sleep deprivation. Surveys of anesthesia personnel have linked fatigue and anesthetic errors, but these contain self-reported data that may not be verifiable.56 In a study of performance on an anesthesia simulator, residents in the sleep-deprived condition demonstrated progressive impairment of alertness, mood, and performance and had longer response latency to vigilance probes.54In spite of this, there were no significant differences in the clinical management of the simulated patients between the rested and sleep-deprived groups. Subsequent to a period of sleep deprivation, performance does not return to normal levels until 24 hours of rest and recovery has occurred. An interesting phenomenon is the “end-spurt,” in which previously deteriorated performance shows improvement when the subject realizes that the task is 90% completed. The converse undoubtedly also occurs, a “let-down” with additional deterioration in performance when the procedure is unexpectedly prolonged.
The sleep-loss pattern experienced by anesthesiologists who take night call is complex and includes elements of each of the three general classes of sleep deprivation: total, partial, and selective sleep deprivation. Selective sleep deprivation resulting from frequent interruptions is most disruptive to important components of sleep including slow-wave sleep (associated with “body repair”) and rapid eye movement sleep (“mind repair”). Indicators of psychosocial distress, including irritability, displaced anger, depression, and anxiety, have all been identified in house officers suffering from sleep deprivation.63 An additional area of concern is the potential effect of sleep deprivation and chronic fatigue on health and psycho-social adjustment. Work schedules that disrupt circadian rhythms are associated with impaired health, emotional problems, and a decline in performance.
National attention was focused on the problems associated with sleep-deprived medical housestaff by the well-publicized Libby Zion case. A large portion of this claim hinged on the allegation that fatal, avoidable mistakes were made by exhausted, unsupervised residents. A number of medical organizations and state legislatures subsequently took action to limit excessive work hours and resultant sleep deprivation among physicians, especially trainees. For example, the Accreditation Council for Graduate Medical Education (ACGME) has set universal standards that limit resident duty hours to an average of 80 hours per week and no more than 30 hours at any one time, limit the frequency of in-house call, and mandate that “off-duty” time be provided. Unfortunately, no regulations pertain to the practicing anesthesiologist or nurse anesthetist. In this area, medicine remains significantly behind other industries, most notably the transport and airline industries, in identifying and regulating work practices that permit excessively long shifts.59
After ACGME set duty hour limits for residents in 2003, investigators have attempted to assess the effects. Although studies suggest that residents' quality of life has generally improved, the effect on education is uncertain because many of the studies contain significant method flaws.64 There have been conflicting reports on whether duty hour limits have resulted in improved patient outcome.65,66 Although it was expected that reducing resident fatigue would be associated with fewer medical errors, duty hour limits may have created unintended consequences, such as the loss of continuity of care, an increased likelihood for failure to transmit critical information when responsibility for care is transferred at the end of shifts, and the allocation of many medical tasks typically performed by residents to nonphysician extenders.
Several strategies can be used to prevent fatigue and the effects of sleep deprivation during long work periods.59 Personnel should be educated on the problems associated with poor sleep habits outside the hospital. Naps prior to the start of call as well as the use of caffeine can improve alertness during long shifts. Modafinil may be useful to treat sleepiness in individuals with shift-work sleep disorder.67
Anesthesia personnel are at risk for acquiring infections both from patients and from other personnel. Viral infections, reflecting their prevalence in the community, are the most significant threat to HCWs. Most commonly, these are spread through the respiratory route—a mechanism that is, unfortunately, the most difficult to control effectively. Other infections are propagated by hand-to-hand transmission, and hand washing is considered the single most important intervention for protection against this form of contagion.68Immunity against some viral pathogens can be provided through vaccination.69 Blood-borne pathogens such as hepatitis and human immunodeficiency virus (HIV) cause serious infections, but transmission can be prevented with mechanical barriers blocking portals of entry or, in the case of hepatitis B, by producing immunity by vaccination.70 Current recommendations from the Centers for Disease Control and Prevention (CDC) for pre-employment screening, infection control practices, vaccination, postexposure treatment, and work restrictions for infected personnel should be consulted for specific information related to each pathogen.70,71,72
Respiratory viruses, which are responsible for many community-acquired infections, are usually transmitted by two routes. Small-particle aerosols produced by coughing, sneezing, or talking can propel viruses over large distances. The influenza and measles viruses are spread in this way. The second mechanism involves large droplets produced by coughing or sneezing, contaminating the donor's hands or an inanimate surface, whereupon the virus is transferred to the oral, nasal, or conjunctival mucous membranes of a susceptible person by self-inoculation. Rhinovirus and respiratory syncytial virus (RSV) are spread by this process.
Because influenza viruses are easily transmitted, community epidemics of influenza are common, with large outbreaks occurring annually. Acutely ill patients shed virus through small-particle aerosols by coughing or sneezing for as long as 5 days after the onset of symptoms. Respiratory isolation precautions can be used for the duration of the clinical illness in an attempt to prevent spread to susceptible individuals. Because of their contact with nasopharyngeal secretions, anesthesiologists can play a role in the spread of influenza virus in hospitals.
Influenza rarely produces significant morbidity in healthy personnel but can result in high rates of absenteeism. Hospital staff, especially those who care for patients in high-risk groups, should be immunized annually (October or November) with the inactivated (killed virus) influenza virus vaccine.72 Antigenic variation of influenza viruses occurs over time, so that new viral strains (usually two type A and one type B) are selected for inclusion in each year's vaccine.
In the United States, there are four antiviral agents for chemoprophylaxis and treatment of influenza: amantadine, rimantadine, zanamivir, and oseltamivir.72 Because of a high likelihood of influenza A viral resistance, amantadine and rimantadine are not currently recommended. The neuraminidase inhibitors zanamivir and oseltamivir have been shown to be effective in preventing and treating both influenza A and B. During hospital outbreaks of influenza, the antiviral agents zanamivir and oseltamivir are about 80% effective in preventing influenza infection in unvaccinated hospital personnel and, if administered within 48 hours of the onset of illness, can reduce the duration and severity of illness. Because of possible morbidity to hospitalized patients and to hospital personnel, it is recommended that during community influenza epidemics, hospitals should consider limiting elective admissions and surgery.
In the past century, there have been three influenza pandemics (1918, 1957, and 1968) with the “Great Influenza” in 1918 killing between 40 and 50 million people worldwide. Although the timing and severity cannot be predicted, another influenza pandemic is likely and represents one of the greatest public health threats.d In the event of a pandemic, the large number of infected patients would strain global resources such as health care facilities and equipment (respirators for personnel and ventilators for patients). Containment to prevent the spread of infection requires early identification and isolation of infected individuals to limit disease transmission. For patients requiring hospitalization, specific wards should be established with dedicated staff. NIOSH-certified respirators (N95 or higher) should be used by personnel during activities or procedures likely to generate infectious respiratory aerosols.
Avian Influenza A
Avian influenza virus occurs naturally in birds, but there have been outbreaks in humans.73 The first human cases were reported from Asia, but the virus has been identified in Europe, the Near East, and Africa. Avian influenza A type H5N1 has a human mortality of over 50%. Clinical illness begins as a severe pneumonia that may rapidly progress to acute respiratory distress syndrome. Outbreaks of avian flu have usually occurred in people who have had close contact with infected poultry. Human-to-human transmission is uncommon, but because influenza viruses have the ability to mutate, there is concern that future H5N1 viruses may be capable of spread from one person to another. There is variable susceptibility of the virus to currently available antiviral agents. A vaccine for prophylaxis against avian influenza H5N1 was approved for use in the United States in 2007.
Respiratory Syncytial Virus
RSV is the most common cause of serious bronchiolitis and lower respiratory tract disease in infants and young children worldwide. During periods when RSV is prevalent in the community (usually late November through May in the United States), many hospitalized infants and children may carry the virus. Large numbers of virus are present in respiratory secretions of infected children, and although viable virus can be recovered for up to 6 hours on contaminated environmental surfaces, it is readily inactivated with soap and water and disinfectants. Infection of susceptible people occurs by self-inoculation when RSV in secretions is transferred to the hands, which then contact the mucous membranes of the eyes or nose.74 Although most children have been exposed to RSV early in life, immunity is not permanent and reinfection is common.
RSV may also be a significant cause of illness in healthy elderly patients and those with chronic cardiac or pulmonary disease.75 RSV is shed for approximately 7 days after infection. Hospitalized patients with the virus should be isolated, but during seasonal outbreaks large numbers of patients may make isolation impractical.76 Careful hand washing and the use of gowns, gloves, masks, and goggles (standard precautions) have all been shown to reduce RSV infection in hospital personnel.
Varicella-zoster virus (VZV), herpes simplex virus types 1 and 2, and cytomegalovirus (CMV) are members of the Herpetoviridine family. Close personal contact is required for transmission of all the herpes viruses except for VZV, which is spread by direct contact or small-particle aerosols. After primary infection with herpes viruses, the organism becomes latent and may reactivate at a later time. Most people in the United States have been infected with all of the herpes viruses by middle age. Therefore, nosocomial transmission is uncommon except in the pediatric population and in immunosuppressed patients.
VZV produces both chicken pox and herpes zoster (shingles). Although the primary infection (chicken pox) is usually uncomplicated in healthy children, VZV infection in adults may be associated with major morbidity or death. Infection during pregnancy may result in fetal death or, rarely, in congenital defects. Health care workers with active VZV infection can transmit the virus to others.
After the primary infection, VZV remains latent in dorsal root or extramedullary cranial ganglia. Herpes zoster results from reactivation of the VZV infection and produces a painful vesicular rash in the innervated dermatome. Anesthesiologists working in pain clinics may be exposed to VZV when caring for patients who have discomfort from herpes zoster.
VZV is highly contagious, especially from patients with chicken pox or disseminated zoster. The CDC estimates that the period of communicability begins 1 to 2 days before the onset of the rash and ends when all the lesions are crusted, usually 4 to 6 days after the rash appears.77 Because VZV may be spread through airborne transmission, respiratory isolation should be used for patients with chicken pox or disseminated herpes zoster.76 Use of gloves to avoid contact with vesicular fluid is adequate to prevent VZV spread from patients with localized herpes zoster.
Most adults in the United States have protective antibodies to VZV. Because there have been many reports of nosocomial transmission of VZV, it is recommended that all HCWs have immunity to the virus. Anesthesia personnel should be questioned about prior VZV infection, and those with a negative or unknown history of infection should be serologically tested.77 All employees with negative titers should be restricted from caring for patients with active VZV infection and should be offered immunization with two doses of the live, attenuated varicella vaccine.
Susceptible personnel with a significant exposure to an individual with VZV infection are potentially infective from 10 to 21 days after exposure and should not contact patients
during this period. They should be offered vaccination within 3 to 5 days of the exposure since it might modify the disease. Varicella-zoster immune globulin can also be considered but it is most effective when administered within 96 hours after exposure.77 Personnel without VZV immunity should be reassigned to alternative locations so that they do not care for patients who have active VZV infections.
Herpes simplex virus (HSV) infection is quite common in adults. After viral entry through the mucous membranes of the mouth, the primary infection with HSV type 1 is usually clinically inapparent but may involve severe oral lesions, fever, and adenopathy. In healthy people, the primary infection subsides and the virus persists in a latent state within the sensory nerve ganglion innervating the site of infection. Any of several mechanisms can reactivate the virus to produce recurrent infection, which manifests in the vicinity of the primary lesion.
A second HSV, type 2, is usually associated with genital infections and is spread by sexual contact. Newborns may become infected with HSV type 2 during vaginal delivery.
Health care personnel may be inoculated by direct contact with body fluids carrying either HSV type 1 or 2.
Herpetic infection of the finger, herpetic paronychia or herpetic whitlow, is an occupational hazard for anesthesia personnel. The infection usually begins at the portal of viral entry, a site on the distal finger where the integrity of the skin has been broken, and results in vesicle formation. Within 3 weeks, the throbbing pain lessens and the lesions begin to heal. Use of acyclovir, an antiviral drug that inhibits replication of HSV, may shorten the course of the primary cutaneous viral infection. Personnel with HSV infections of the fingers or hands should not contact patients until their lesions are healed.
CMV infects between 50 and 85% of individuals in the United States before age 40, with most infections producing minimal symptoms. After the primary infection, the virus remains dormant, and recurrent disease only occurs with compromise of the individual's immune system. Transmission of CMV can take place through close contact with an individual excreting the virus or through contact with contaminated saliva or urine. It is unlikely that aerosols or small droplets play a role in CMV transmission.
Primary or recurrent CMV infection during pregnancy results in fetal infection in up to 2.5% of occurrences. Congenital CMV syndrome may be found in up to 10% of infected infants. Thus, although CMV infection usually does not result in morbidity in healthy adults, it may have significant sequelae in pregnant women. CMV infection can also be deadly in immunocompromised patients, such as those undergoing bone marrow transplantation.
The two major populations with CMV infection in the hospital include infected infants and immunocompromised patients, such as those who have undergone organ transplants or those on oncology units. Routine infection control procedures (standard precautions) are sufficient to prevent CMV infection in HCWs (Tables 3-3 and 3-4).71 Pregnant personnel should be made aware of the risks associated with CMV infection during pregnancy and of appropriate infection control precautions to be used when caring for high-risk patients. There is no evidence to indicate that it is necessary to reassign pregnant women from patient care areas in which they may have contact with CMV-positive patients.
Outbreaks of rubella, or German measles, in hospital personnel have resulted in significant loss in employee working time, employee morbidity, and cost to the hospital. Although most adults in the United States are immune to rubella, up to 20% of women of childbearing age are still susceptible. Rubella infection during the first trimester of pregnancy is associated with congenital malformations or fetal death.
Rubella is transmitted by contact with nasopharyngeal droplets spread by infected individuals coughing or sneezing. Patients are most contagious while the rash is erupting but can transmit the virus from 1 week before to 5 to 7 days after the onset of the rash. Droplet precautions should be used to prevent transmission (Table 3-4).76
Table 3-3 Prevention of Occupationally Acquired Infections
Table 3-4 Health Care Isolation Precautionsa
Ensuring immunity at the time of employment (evidence of prior vaccination with live rubella vaccine or serologic confirmation) should prevent nosocomial transmission of rubella to personnel. It has been shown that history is a poor indicator of immunity. A live, attenuated rubella virus vaccine, contained in measles, mumps, rubella vaccine, is available to produce immunity in susceptible personnel.69,78 Many state or local health departments mandate rubella immunity for all HCWs, and local regulations should be consulted.
Measles virus is highly transmissible both by large droplets and by the airborne route. The virus is found in the mucus of the nose and pharynx of the infected individual and is spread by coughing and sneezing. The disease can be transmitted from 4 days prior to the onset of the rash to 4 days after its onset. Airborne precautions should be used for infected patients (Table 3-4).71,76 Introduction of the measles vaccine in the United States has successfully eliminated indigenous cases of measles but importation of measles from other countries continues to occur.
HCWs are at increased risk for acquiring measles and transmitting the virus to susceptible coworkers and patients. The CDC recommends that medical personnel have adequate immunity to measles, as documented by one of the following: evidence of two doses of live measles vaccine, a record of physician-diagnosed measles, or serologic evidence of measles immunity (Table 3-3).69 Susceptible personnel born in or after 1957 should receive two doses of the live measles vaccine at the time of employment.78
Severe Acute Respiratory Syndrome
Severe acute respiratory syndrome (SARS) is a respiratory tract infection produced by a coronavirus, SARS-associated coronavirus (SARS-CoV). After the first cases were reported from Asia in late 2002, the disease quickly spread globally in 2003 before being controlled. Since then, global surveillance for SARS-CoV has detected no confirmed cases. Because of the rapid spread and the significant morbidity and mortality associated with the infection, there is a need to understand the disease. Health care facilities should be prepared to rapidly implement control measures if new outbreaks occur.
SARS typically presents with a high fever, greater than 38.0° C, and is followed with symptoms of headache, generalized aches, and cough. Severe pneumonia may lead to acute respiratory distress syndrome and death. SARS is spread by close person-to-person contact through virus carried in large respiratory droplets and possibly by airborne transmission. The virus can also be spread when an individual touches a contaminated object and then inoculates the mouth, nose, or eyes. Aerosolization of respiratory secretions during coughing or endotracheal suctioning has been associated with transmission of the disease to HCWs, including anesthesiologists and critical care nurses.
One of the most important interventions to prevent the spread of SARS in the health care setting is early detection and isolation of patients who may be infected with SARS-Co[V with dot above]79 Gloves, gown, respiratory protection (as a minimum, use a NIOSH-certified N95 filtering respirator), and eye protection should be donned before entering a SARS patient's room or during procedures likely to generate respiratory aerosols.79
Although many viruses may produce hepatitis, the most common are type A or infectious hepatitis, type B (HBV) or serum hepatitis, and type C (HCV), which is responsible for most cases of parenterally transmitted non-A, non-B hepatitis (NANBH) in the United States. Delta hepatitis, caused by an incomplete virus, occurs only in people infected with HBV. Outbreaks of an enterically transmitted NANBH (hepatitis E) have been reported from outside the United States and are usually caused by contaminated water. The greatest risks of occupational transmission to anesthesia personnel are associated with HBV and HCV.
About 20 to 40% of viral hepatitis in adults in the United States is caused by the type A virus. Hepatitis A is usually a self-limited illness, and no chronic carrier state exists. Spread is predominantly by the fecal–oral route, either by person-to-person contact or by ingestion of contaminated food or water. Outbreaks are usually found in institutions or other closed groups where there has been a breakdown in normal sanitary conditions. Hospital personnel do not appear to be at increased risk for hepatitis A and nosocomial transmission is rare. Personnel exposed to patients with hepatitis A should receive immune globulin intramuscularly as soon as possible but not more than 2 weeks after the exposure to reduce the likelihood of infection.80 Immune globulin provides protection against hepatitis A through passive transfer of antibodies and is used for postexposure prophylaxis. Hepatitis A vaccine is not routinely recommended for HCWs except for those that may be working in countries where hepatitis A is endemic.69,80
Hepatitis B is a significant occupational hazard for nonimmune anesthesiologists and other medical personnel who have frequent contact with blood and blood products. The prevalence (the proportion of people who have or have had the condition at the time of the survey) of hepatitis B in the general population of the United States is 3 to 5%, and the carrier rate is 0.2 to 0.9% based on serologic screening. Serosurveys conducted in the United States and several other countries in the 1980s included more than 2,400 unvaccinated anesthesia personnel and demonstrated a mean prevalence of HBV serologic markers of 17.8% (range, 3.2 to 48.6%).81. Before the widespread usage of hepatitis B vaccine the prevalence of hepatitis B serologic markers in anesthesia personnel ranged from 19 to 49% and reflected the prevalence of HBV carriers in the referral population for the area.
Acute HBV infection may be asymptomatic and usually resolves without significant hepatic damage. Less than 1% of acutely infected patients develop fulminant hepatitis. Approximately 10% become chronic carriers of HBV (i.e., serologic evidence demonstrated for >6 months). Within 2 years, half of the chronic carriers resolve their infection without significant hepatic impairment. Chronic active hepatitis, which may progress to cirrhosis and is linked to hepatocellular carcinoma, is found most commonly in individuals with chronic viral infection for >2 years.
The diagnosis and classification of the stage of HBV infection can be made on the basis of serologic testing. Antibody to the surface antigen (anti-HBs) appears with resolution of the acute infection and confers lasting immunity against subsequent HBV infections. Chronic HBV carriers are likely to have hepatitis B surface antigen (HBsAg) and antibody to the core antigen (anti-HBc) present in serum samples. The presence of hepatitis B e antigen (HBeAg) in serum is indicative of active viral replication in hepatocytes.
Anesthesia personnel are at risk for occupationally acquired HBV infection as a result of accidental percutaneous or mucosal contact with blood or body fluids from infected patients. Patient groups with a high prevalence of HBV include immigrants from endemic areas, users of illicit parenteral drugs, homosexual men, and patients on hemodialysis.70 Carriers are frequently not identified during hospitalization because the clinical history and routine preoperative laboratory tests may be insufficient for diagnosis. The risk for infection after an HBV-contaminated percutaneous exposure, such as an accidental needle stick, is 37 to 62% if the source patient is HBeAg-positive and 23 to 37% if HBeAg-negative. HBV can be found in saliva, but the rate of transmission is significantly less after mucosal contact with infected oral secretions than after percutaneous exposures to blood. HBV is a hardy virus that may be infectious for at least 1 week in dried blood on environmental surfaces.
Hepatitis B is now a preventable and a treatable disease. The implementation of routine vaccination has dramatically reduced the incidence of new cases in the U.S. population. In addition to vaccination, use of standard precautions, use of safety devices, and postexposure prophylaxis have significantly reduced the risk of occupationally acquired HBV infection and its sequelae in HCW.
Hepatitis B Vaccine
Use of hepatitis B vaccine is the primary strategy to prevent occupational transmission of HBV to anesthesia personnel and other HCWs at increased risk.70 Administration of three doses of vaccine into the deltoid muscle results in the production of protective antibodies (anti-HBs) in >90% of healthy HCWs. Hospitals or anesthesia departments should have policies for educating, screening, and counseling personnel about their risk of acquiring HBV infection and should make vaccination available for susceptible personnel.70,82
To ensure adequate postvaccination immunity, serologic testing for anti-HBs should take place within 1 to 2 months
after the third dose of vaccine.70 Protective antibodies develop in 30 to 50% of nonresponders (i.e., anti-HBs <10 mIU/mL) with a second three-dose vaccine series. Nonresponders to vaccination, who are HBsAg-negative, remain at risk for HBV infection and should be counseled on strategies to prevent infections and the need for postexposure prophylaxis.
Vaccine-induced antibodies decline over time, with maximum titers after vaccination correlating directly with duration of antibody persistence. The CDC states that for vaccinated adults with normal immune status, routine booster doses are not necessary and periodic monitoring of antibody concentration is not recommended.70
When susceptible or nonvaccinated anesthesia personnel have a documented exposure to a contaminated needle or to blood from an HBsAg-positive patient, postexposure prophylaxis with HBV hyperimmune globulin is recommended.70 Hepatitis B vaccine should be offered to any unvaccinated, susceptible person who sustains a blood or body fluid exposure.
HCV causes most cases of parenterally transmitted NANBH and is a leading cause of chronic liver disease in the United States. Although antibody to HCV (anti-HCV) can be detected in most patients with hepatitis C, its presence does not correlate with resolution of the acute infection or progression of hepatitis, and it does not confer immunity against HCV infection.83 Seropositivity for HCV RNA is a marker of chronic infection and continued viral presence. Six major genotypes of HCV have been identified with the specific genotype being predictive for the response to and the needed duration of antiviral therapy.
Most cases of acute HCV infection are asymptomatic, and up to 40% will clear the infection within 6 months. Chronically infected individuals have a high rate of progression to chronic hepatitis with about 20% developing cirrhosis. Hepatocellular carcinoma occurs in 1 to 4% of cirrhotic patients per year. Combination therapy with interferon alpha (standard or pegylated) and ribavirin has been effective in the treatment of some cases of acute and chronic hepatitis C.84
Like HBV, HCV is transmitted through blood, but the rate of occupational HCV infection is less than for HBV. Although HCV transmission has been documented in health care settings, the prevalence of anti-HCV in HCWs in the United States is not greater than that found in the general population (1.6%). The greatest risk of occupational HCV transmission is associated with exposure to blood from an HCV-positive source, and the average rate of seroconversion after accidental percutaneous exposure is 1.8%.70 HCV has been transmitted through blood splashes to the eye and with exposure via nonintact skin. HCV in dried blood on environmental surfaces may remain infectious for up to 16 hours, but environmental contamination does not appear to be a common route of transmission. Although HCV can be found in the saliva of infected individuals, it is not believed to represent a great risk for occupational transmission.70
There is no vaccine or effective postexposure prophylaxis available to prevent HCV infection, and use of immune globulin is no longer recommended after a known exposure.70Antiviral agents like interferon or ribavirin are not recommended as effective prophylaxis after occupational exposure. Prevention of exposures remains as the primary strategy for protecting HCWs against HCV infection. Personnel who have had a percutaneous or mucosal exposure to HCV-positive blood should have serologic testing for anti-HCV and alanine aminotransferase and counseling at the time of the exposure and at 6 months.70
Pathogenic Human Retroviruses
HIV Infection and Acquired Immunodeficiency Syndrome
The agent that produces acquired immunodeficiency syndrome (AIDS) is the human immunodeficiency virus (HIV), one of several pathogenic human retroviruses. Current estimates suggest that 650,000 to 900,000 people in the United States are infected with HIV, and one of four is unaware that they are HIV-positive. According to CDC data, from 1981 through December 2005 there have been about 956,000 cases of AIDS in the United States.85 In 2005, it is estimated that globally there are 38.6 million persons living with HIV.
The initial infection with HIV presents clinically as a mononucleosis-like syndrome with lymphadenopathy and rash. Although the patient then enters an asymptomatic period, monocyte-macrophage cells serve as a reservoir for the virus throughout the body, and CD4+ T cells harbor the virus in the blood. Within a few weeks after infection, an antibody may be detected by the enzyme immunoassay or a rapid HIV antibody test, but a positive result must be confirmed using the more specific Western blot or immunofluorescent assay. After a variable length period of asymptomatic HIV infection, there is an increase in viral titer and impaired host immunity, resulting in opportunistic infections and malignancies characteristic of AIDS. As the use of highly active antiretroviral therapy became widespread in the United States in 1996, the average time of survival after HIV infection increased.
HIV is spread by sexual contact (especially homosexual males), perinatally from infected mother to neonate, and through infected blood (transfusion or shared needles) and blood products. Although the virus can be found in saliva, tears, and urine, these body fluids have a low risk for viral transmission. Many HIV-infected patients in health care settings may not be identified as such by their initial or presenting diagnosis.
Risk of Occupational HIV Infection
Although there are several modes of transmission for HIV infection in the community, the most important source for occupational transmission of HIV to the HCW is blood contact.70The rate of seroconversion in HCWs sustaining a percutaneous exposure (needlestick injury) to HIV-infected blood is estimated to be 0.3%,86 while the rate after a mucous membrane exposure is 0.09%.87 Transmission has occurred after blood exposure to nonintact skin, but although the rate is unknown, it is likely less than for mucous membrane exposure.
A case-control study has demonstrated that specific factors are associated with an increased rate of HIV transmission after a percutaneous injury.88 Increased risk was associated with a deep injury, visible blood on the device producing the injury, a procedure in which the needle was placed in an artery or vein, and terminal illness (death from AIDS within 2 months) in the source patient. Therefore, the risk of occupational HIV transmission is greatest after a deep injury with a blood-filled, large-gauge, hollow-bore needle used on a patient in the terminal phase of AIDS.
The occupational risk of HIV infection is a function of the annual number of blood exposures, the rate of HIV transmission with each exposure to infected blood, and the prevalence of HIV infection in the specific patient population. Greene et al89 prospectively collected data on 138 contaminated percutaneous
injuries to anesthesia personnel. The rate of contaminated percutaneous injuries per year per full-time equivalent anesthesia worker was 0.42, and the average annual risk of HIV and HCV infection was estimated to be 0.0016 and 0.015%, respectively.
Anesthesia personnel are frequently exposed to blood and body fluids during invasive procedures such as insertion of vascular catheters, arterial punctures, and endotracheal intubation.89,90 Although many exposures are mucocutaneous and can be prevented by the use of gloves and protective clothing, these barriers do not prevent percutaneous exposures such as needlestick injuries, which carry a greater risk for pathogen transmission. Because of the tasks they perform, anesthesia personnel are likely to use and be injured by large-bore, hollow needles such as intravenous catheter stylets and needles on syringes.89,91 Needleless or protected needle safety devices can be used to replace standard devices to reduce the risk of needlestick injuries. Although safety devices usually are more expensive than a comparable nonsafety item, they may be more cost-effective when the cost of needlestick injury investigation and medical care for infected personnel is considered.
Percutaneous injuries have now been accepted as a significant occupational risk for HCWs. The Needlestick Safety and Prevention Act of 2000 mandated that OSHA update its Bloodborne Pathogen Standard to require that exposure control plans include a process for evaluating and implementing the use of commercially available safety medical devices.82Employers were also required to maintain a “sharps” injury log to collect data to evaluate exposure risks and the effectiveness of safety devices. Because federal regulations require the use of safety devices, as new technologies become available, clinicians must assess these within their practice to determine which are most effective for specific tasks.
Postexposure Treatment and Prophylactic Antiretroviral Therapy
When personnel have been exposed to patients' blood or body fluids, the incident should immediately be reported to the employee health service or the designated individual within the institution. Based on the nature of the injury, the exposed worker and the source individual should be tested for serologic evidence of HIV, HBV, and HCV infection.70 Current local laws must be consulted to determine policies for testing the source patient, and confidentiality must be maintained. When the source patient is found to be HIV-positive, the employee should be retested for HIV antibodies at 6 and 12 weeks and at 6 months after exposure, although most infected people are expected to undergo seroconversion within the first 6 to 12 weeks. During this period, the exposed employee should follow CDC recommendations for preventing transmission of HIV to family members and patients.70 If the source patient is found to be HIV-negative, no additional treatment is required.
The U.S. Public Health Service recommends that antiretroviral postexposure prophylaxis (PEP) be offered to HCWs who have incurred a significant percutaneous exposure to HIV-infected blood.92 The specific antiretroviral regimen is based on the severity of exposure and the source patient. Because protocols for chemoprophylaxis are likely to change with additional research and the introduction of new antiretroviral drugs, the most current recommendations should be consulted prior to instituting postexposure prophylactic therapy. To be most effective, PEP should be initiated as soon as possible after exposure (<24 hours) and continued for 4 weeks. HCWs should be counseled on the potential toxic effects of antiretrovirals so that they can make an informed decision on the risks associated with PEP. Failure of PEP has been attributed to large viral inoculum, use of a single antiviral agent, drug resistance in the virus from the source patient, and delayed initiation or short duration of PEP therapy.
Occupational Safety and Health Administration Standards, Standard Precautions, and Transmission-Based Precautions
In the late 1980s the CDC formulated recommendations, or universal precautions, for preventing transmission of blood-borne infections (including HIV, HBV, and HCV) to HCWs. The guidelines were based on the epidemiology of HBV as a worst-case model for transmission of blood-borne infections and available knowledge of the epidemiology of HIV and HCV. Because some carriers of blood-borne viruses could not be identified, universal precautions were recommended for use during all patient contact. Although exposure to blood carries the greatest risk of occupationally related transmission of HIV, HBV, and HCV, it was recognized that universal precautions should also be applied to semen, vaginal secretions, human tissues, and the following body fluids: cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic. Subsequently, the CDC synthesized the major features of universal precautions into standard precautions, a single set of precautions that should be applied to all patients since every person is potentially infected or colonized with an organism that might be transmitted during care (Table 3-4).76 Standard precautions were included in a more complete set of isolation precautions, which contain guidelines (contact precautions, droplet precautions, and airborne precautions) to reduce the risk of transmission of blood-borne and other pathogens in health care settings.76
Standard precautions include the appropriate application and use of hand washing, personal protective equipment (PPE), and respiratory hygiene/cough etiquette. The selection of specific barriers or PPE should be commensurate with the task being performed. Gloves should be worn during any contact with mucous membranes and oral fluids, such as during endotracheal intubation and pharyngeal suctioning. Gloves may be all that is necessary during insertion of a peripheral intravenous catheter, whereas gloves, gown, mask, and face shield may be required during endotracheal intubation in a patient with hematemesis or during bronchoscopy or endotracheal suctioning. Gloves should be removed after they become contaminated to prevent dissemination of blood or body fluids to equipment or other items that may be contacted by ungloved personnel. Waterless antiseptics should be available to permit anesthesia personnel to wash their hands without leaving the operating room after glove removal. Respiratory hygiene/cough etiquette, to contain respiratory secretions in patients, has been added to standard precautions to prevent droplet transmission of respiratory pathogens, especially during seasonal outbreaks.
OSHA has promulgated standards to protect employees from occupational exposure to blood-borne pathogens.82 Employers subject to OSHA must comply with these federal regulations. The standard requires that there must be an exposure control plan specifically detailing the methods that the employer is providing to reduce employees' risk of exposure to blood-borne pathogens. The employer must evaluate engineering controls such as needleless devices to eliminate hazards. Work practice controls are encouraged to reduce blood exposures by altering the manner in which personnel perform tasks (e.g., an instrument rather than fingers should be used to handle needles). The employer must furnish appropriate PPE (e.g., gloves, gowns) in various sizes to permit employees to comply with standard precautions. The HBV vaccine must be offered
at no charge to personnel. A mechanism for postexposure treatment and follow-up must be provided. An annual educational program should inform employees of their risk for blood-borne infection and the resources available to prevent blood exposures. Implementation of standard precautions and OSHA regulations have been effective in decreasing the number of exposure incidents that result in HCW contact with patient blood and body fluids.
Creutzfeldt-Jakob disease (CJD), caused by an infectious protein or prion, may be unsuspected in patients presenting with dementia.93 The prion protein enters brain cells and induces abnormal folding of cellular proteins leading to irreversible damage with loss of neurons. More recently, it has been recognized that the prion strain associated with bovine spongiform encephalopathy may infect humans to produce a variant CJD (vCJD). There have been no reported cases of direct human-to-human transmission of CJD or vCJD by casual or environmental contact, droplet, or airborne routes. Iatrogenic transmission of CJD or vCJD to patients has taken place through contaminated biologic products and neurosurgical instruments and via blood transfusion. The risk of transmission to hospital personnel is unknown because surveillance is complicated by the long period from the time of infection until the onset of symptoms. Standard precautions should be used. Tissues with greatest risk of infectivity are brain, spinal cord, and eyes.
The prion is difficult to eradicate from equipment, and special sterilization methods are required for instruments that come into contact with high-infectivity tissues. The World Health Organization has developed infection control and sterilization guidelines for CJD.e
The incidence of tuberculosis (TB) in U.S.-born residents has declined since 1992 while the rate among foreign-born individuals living in the United States has increased over the same period. Although most individuals infected with TB are treated on an outpatient basis, undiagnosed patients may be hospitalized for the workup of pulmonary pathology or unrelated causes. Hospital personnel are especially at risk for infection from unrecognized cases.94,95 Groups with a higher prevalence of TB include (1) personal contacts of people with active TB, (2) people from countries with a high prevalence of TB, and (3) certain populations such as the medically underserved or those living in congregate settings like homeless shelters or correctional facilities.94 Global surveillance has documented the emergence of multidrug-resistant TB (resistance to at least two of the primary treatments, isoniazid and rifampin) as well as extensively drug-resistant organisms (resistance to at least two of the primary treatments, isoniazid and rifampin, and to any fluoroquinolone and at least one of three injectable drugs). Several hospital outbreaks of multidrug-resistant Mycobacterium tuberculosis infection have been reported.95,96 Mortality associated with these outbreaks is high.
Mycobacterium tuberculosis can be transmitted over great distances through viable bacilli carried on airborne particles, 1 to 5 µm in size, by coughing, speaking, or sneezing. Airborne precautions should be used for individuals suspected of having TB until they are confirmed as nontransmitters by repeat sputum examination that demonstrates no bacilli.94Outbreaks of TB in health care facilities have been attributed to delayed diagnosis of TB in the source patient, delayed initiation of or inadequate airborne precautions, lapses in precautions during aerosol-generating procedures, and lack of adequate respiratory protection in HCWs. Administration of appropriate chemotherapy for sufficient duration is required to cure the individual patient, but treatment also benefits the community by preventing spread of the infection.97
A decrease in the health care-associated transmission of TB has been attributed to the rigorous implementation of infection-control measures. Effective prevention of spread to HCWs requires early identification of infected patients and immediate initiation of airborne infection isolation (negative-pressure rooms with air vented outside; see Table 3-4).94 Patients must remain in isolation until adequate treatment is documented. If patients with TB must leave their rooms, they should wear face masks to prevent spread of organisms into the air. HCWs should wear fit-tested respiratory protective devices when they enter an isolation room or when performing procedures that may induce coughing, such as endotracheal intubation or tracheal suctioning.94 The CDC recommends that respiratory protective devices worn to protect against M. tuberculosis should be able to filter 95% of particles 1 mm in size at flow rates of 50 L/min and should fit the face with a leakage rate around the seal of <10% documented by fit testing.94 High-efficiency particulate air respirators (classified as N95) are NIOSH-approved devices that meet the CDC criteria for respiratory protective devices against M. tuberculosis.98. Elective surgery should be postponed until infected patients have had an adequate course of chemotherapy. If surgery is required, bacterial filters (high-efficiency particulate filters) should be used on the anesthetic breathing circuit for patients with TB.94 Patients must be recovered in a room that meets all the requirements for airborne precautions.
Routine periodic screening of employees for TB should be included as part of a hospital's employee health policy with the frequency of screening dependent on the prevalence of infected patients in the hospitalized population. When a new conversion is detected by skin testing, a history of exposure should be sought to determine the source patient. Treatment or preventive therapy is based on the drug-susceptibility pattern of the M. tuberculosis in the source patient, if known.
Viruses in Smoke Plumes
The laser is commonly used for vaporizing carcinomatous tumors and lesions that may contain active viruses. Use of lasers and electrosurgical devices is associated with several hazards, both to patients and to operating room personnel. Risks include thermal burns, eye injuries, electrical hazards, and fires and explosions. There is evidence that the smoke plumes resulting from tissue vaporization contain toxic chemicals such as benzene and formaldehyde, and in 1996, NIOSH released a health hazard alert on the dangers of smoke plumes.99
Clinical and laboratory studies have demonstrated that when the carbon dioxide laser is used to treat verrucae (papilloma and warts), intact viral DNA could be recovered from the plume. Viable viruses can be found in plumes produced by both carbon dioxide and argon laser vaporization of a virus-loaded culture plate, but viable viruses are carried on larger particles that travel <100 mm from the site being vaporized.100
A case report describes laryngeal papillomatosis in a surgeon who had used a laser to remove anogenital condylomas from several patients.101 Although DNA analysis of the surgeon's papillomas revealed a viral type similar to that of the condylomas, proof of transmission is lacking.
To protect operating room personnel from exposure to the viral and chemical content of the laser plume, it is recommended that a smoke evacuation system with a high-efficiency filter be used with the suction nozzle being held as close as possible to the tissue being vaporized.102 In addition, operating room personnel working in the vicinity of the laser plume should wear gloves, goggles, and high-efficiency filter masks (N95 respirators).90,102
Stress is a well-recognized element of the operating room workplace. However, there is very little objective information specifically directed toward understanding the nature of job-related stress among anesthesiologists.103,104 Stress is a nonspecific response to any change, demand, pressure, challenge, threat, or trauma.48 There are three distinct components of the stress response: the initiating stressors, the psychological filters that process and evaluate the stressors, and the coping mechanisms that are employed in an attempt to control the stressful situation.
Stress on the job is unavoidable and to a certain degree is desirable. A moderate, manageable level of stress is the fuel necessary for individual achievement. Hans Seyle,105 a pioneer in the modern study of stress, described a beneficial effect resulting from mild, brief, and controllable episodes of stress. As succinctly stated by Seyle,105 “The absence of stress is death.” On the other hand, extreme degrees of stress, especially in the workplace, can result in mental or physical disease.106 Exactly how an individual responds to a particular stressor is the product of a number of factors, including age, gender, experience, pre-existing personality style, available defense and coping mechanisms, support systems, and concomitant events (such as sleep deprivation).
The workplace of an anesthesiologist frequently mirrors the circumstances that classically define a stressful workplace. There is a background of chronic, low-level stress punctuated by intermittent episodes of extreme stress. The demands are externally paced, usually out of the anesthesiologist's control. Habituation to the demands is difficult. Perturbations are intermittently but continuously inserted into the system. Finally, failure to meet the demands imposed by the workplace can result in serious consequences.
Certain stressors are specific to the practice of anesthesiology. Concerns about liability, long working hours and night call, production pressures, economic uncertainty, and interpersonal relations are frequently cited as sources of chronic stress for anesthesiologists. The process of inducing anesthesia (particularly with a difficult airway) can be among the most profound sources of acute stress to anesthesiologists. Physiologic changes, including heart rate and rhythm, elevations in blood pressure, and myocardial ischemia, are not uncommon. One study reported increases in the blood pressure and heart rate of anesthesiologists during all stages of the anesthetic procedure, especially during the induction.107There was an inverse relationship between the years of experience of the anesthesiologist and the degree of stress as manifested by heart rate change.
Interpersonal relationships impose a set of demands that can be a major source of stress to an anesthesiologist. The operating room is unique as one of the few hospital sites where two co-equal physicians simultaneously share responsibility for the care of a patient. As a result, there exist overlapping realms of clinical responsibility that can upset the customary hierarchy of command. To many anesthesiologists, as well as surgeons, this shared responsibility is the source of greatest conflict and professional stress.50 Other workplace settings, most notably the airline industry, have made better progress in identifying and correcting sources of interpersonal friction that facilitate stress and lead to professional errors.108
Several personality traits, in many cases identifiable before entrance to medical school, can be predictive of the potential toward maladaptive responses to stress. Prominent among these is the obsessive-compulsive, dependent character structure. These individuals typically manifest pessimism, passivity, self-doubt, and feelings of insecurity. They commonly respond to stress by internalizing anger and becoming hypochondriacal and depressed. Undergraduate students who demonstrate these characteristics were more likely to have their medical careers disrupted by alcoholism or drug abuse, psychiatric illness, and marital disturbances.109,110 A number of adaptive coping functions are useful for successful stress management.48 Only when appropriate coping mechanisms become overwhelmed by the magnitude of the stress do the defenses tend to become inappropriate. This situation can give rise to maladaptive behavior and the personal and professional deterioration that can lead to disorders such as drug addiction, professional burnout, and suicide.
Substance Use, Abuse, and Addiction
Illicit drug use remains one of our society's major afflictions. It is estimated that 20 million Americans are drug abusers, with some 5 million addicted. Substance abuse is characterized by significant adverse consequences resulting from the repeated use of a substance.111 With addiction, the individual continues to use a substance in spite of having significant substance-related problems including symptoms of withdrawal, the need for larger amounts of the substance, unsuccessful attempts to control its use, and the need to spend increasing amounts of time seeking the substance. With time, addiction leads to health, social, and economic problems. The term, chemical dependence, is sometimes used rather than addiction, but it is a more generic term covering physical or psychological dependency to a psychoactive substance.
The abuse of drugs and consequent addiction by physicians has attracted considerable media attention and notoriety. Recognition of the problem of substance abuse among physicians is not new. In the first edition of The Principles and Practice of Medicine, edited by Sir William Osler and published in 1892, it is stated: “The habit (morphia) is particularly prevalent among women and physicians who use the hypodermic syringe for the alleviation of pain, as in neuralgia or sciatica.”
It is debatable whether substance abuse is more prevalent among physicians than the general population. Hughes et al112 found that physicians abused alcohol, minor opiates, and benzodiazepine tranquilizers more frequently than the general population. In many cases, the prescription drugs were self-prescribed and were considered by the physician to be “self-treatment.” On the other hand, physicians were less likely to use tobacco or illicit substances. A report from the National Institute on Drug Abuse concludes that HCWs suffer from chemical dependency (including alcohol abuse) at a rate roughly equivalent to that of the general population (8 to 12%).113
In the event that a drug-related problem does exist, physicians are less likely than the population in general to seek professional assistance. Denial plays a major role in this reluctance to undergo counseling or therapy. Medical students learn early in their education to use denial to enable them to endure long, sleepless nights and the personal shortcomings that inevitably accompany the practice of medicine. These
well-developed denial mechanisms enable the physician-addict to conclude that his or her problem is minor and that self-treatment is possible. Physicians typically enter programs for treatment only after they have reached the end stages of their illness.
It is commonly reported that chemical dependency is a specific problem for the specialty of anesthesiology and represents its primary occupational hazard.114 One example of the increased incidence of substance abuse among anesthesiologists comes from early reports from the Medical Association of Georgia Disabled Doctors' Program.115 Anesthesiologists constituted 12% of physician patients treated at the center although they represented only 3.9% of American physicians. On the other hand, other studies have failed to identify an overall excess prevalence of substance abuse among anesthesiologists with the notable exception of major opiates.116,117
One very troubling aspect of this problem is the increased incidence of substance abuse reported among anesthesiology residents. In the report from the Medical Association of Georgia Disabled Doctors' Program,115 anesthesiology residents constituted 33.7% of the resident population of the treatment group, despite representing only 4.6% of the resident population. The incidence of controlled substance abuse within anesthesiology training programs is estimated to be 1 to 2%.118 This statistic is particularly significant because it has persisted despite an increased emphasis placed on education and accountability of controlled substances. ACGME requirements mandate that anesthesiology residency programs have a written policy and an educational program regarding substance abuse, but these efforts have not successfully addressed the problem of substance abuse in training programs.
The Disease of Addiction
What accounts for this unacceptably high prevalence of substance abuse and addiction among anesthesiologists? To answer this, it is important to understand addiction as a chronic psychosocial, biogenetic disease.119 Addiction shares many characteristics with other common chronic illnesses: it is a primary condition (not a symptom), it has established causes, it is associated with specific anatomic and physiologic changes, it has a set of recognizable signs and symptoms, and if left untreated, it has a predictable, progressive course.
The causative factors in this disease process involve a genetic predisposition as well as the environment. The disease results from a dynamic interplay between a susceptible host and a “favorable” environment. Vulnerability in the host is an important factor and may account for 40 to 60% of the risk for addiction. What constitutes an instigating exposure to a drug in one person may have absolutely no effect on another. Unfortunately, there is not a predictive tool to identify the susceptible individual until he or she gets the disease.
Causative factors thought to be specific to certain anesthesiologists include job stress, an orientation toward self-medication, lack of external recognition and self-respect, the availability of addicting drugs, and a susceptible premorbid personality. Self-prescription and recreational use of drugs are commonly seen as a prelude to more extensive substance abuse and dependence. Of concern is the increasing recreational use of drugs among younger physicians and medical students and the choice of more potent drugs with enhanced potential for addiction, such as cocaine, the synthetic opioids, and some of the newer inhalation anesthetics. Most notable has been the significant increase in propofol abuse among residents.120 This may be attributable to the lack of pharmacy accounting or control of this drug in many centers.
Anesthesiologists work in a climate in which large quantities of powerful psychoactive drugs are readily available and are unique among physicians because they usually prescribe as well as personally administer these drugs. In contrast, physicians in most other specialties prescribe medications while other personnel administer them. Because availability of drugs plays a role in the onset of this disease, attention has been directed toward programs to enforce increased accountability and regulation of controlled substances.121 However, despite widespread application of protocols to enforce greater accountability, such as satellite pharmacies for operating suites, the frequency of substance abuse has changed little, if at all, in recent years.118
There is an apparent association between behavior before entering medical school and subsequent development of substance abuse.122 Personality profiles of anesthesiologists have suggested a disturbingly high proportion that may be associated with a predisposition toward maladaptive behavior. Talbott et al115 have observed that many of the anesthesia residents in their treatment program specifically chose the specialty of anesthesiology because of the known availability of powerful drugs.
The consequences of untreated addiction are ultimately devastating. There is a gradual and inexorable deterioration in professional, family, and social relationships. The substance abuser becomes increasingly withdrawn and isolated, first in his or her personal life, and ultimately in his or her professional existence (Table 3-5). Every attempt is made to maintain a facade of normality at work because discovery means isolation from the source of the abused drug. When professional conduct is finally impaired such that it is apparent to the physician's colleagues, the disease is approaching its end stage.
If not detected and treated, addiction is often a fatal illness. Using mortality data collected between 1979 and 1995, Alexander et al14 calculated a relative risk of 2.79 for drug-related deaths among anesthesiologists compared to a matched cohort of internists. Menk et al123 found 14 drug-related deaths among the 79 drug abusers who had been re-enrolled in anesthesiology residencies after treatment. Using data from a more recent survey, Collins et al124 reported that there were nine deaths in 100 residents who retured to and remained in anesthesiology training programs after treatment for chemical dependence. In addition to health hazards, there are significant legal and medicolegal considerations that may affect chemically dependent physicians.114 Laws and regulations vary by state but they detail the necessary steps for handling the drug-abusing physician. In many states disciplinary action and criminal penalties can be imposed on physicians who knowingly fail to report an impaired colleague. Disciplinary action taken against an impaired physician must also be reported to the National Practitioner Data Bank to be in compliance with federal law. Most state medical societies have sanctioned physicians health programs. When chemically dependent physicians seek treatment through this venue, the legal impact may be mitigated, and the disease can be effectively treated.
Debate continues regarding the issue of compulsory random drug testing of physicians.125 Pre-employment and/or random drug screening is already well established in various industries, especially those with high public health profiles (nuclear, aviation, military). Many chairs of academic anesthesiology programs have indicated a willingness to initiate a program of random drug screening of their staff.118 Although random drug testing is an established element of most re-entry contracts for recovering anesthesiologists, serious questions remain about the legality of this approach and its effectiveness in preventing substance abuse. Because fentanyl and sufentanil are the drugs abused by many chemically dependent anesthesiologists and because routine drug screens do not detect these agents, tests that effectively identify their use are expensive and have limited availability.
When there are sufficient data to identify an anesthesiologist as having the disease of addiction, an intervention should be conducted by an experienced individual. The purpose of the intervention is to demonstrate to the anesthesiologist that he or she has the disease and to immediately have the person
enter a facility for evaluation and treatment. The physician, or his or her colleagues, should consider referral to a state-affiliated physicians health program.f Treatment usually begins with inpatient therapy progressing to outpatient sessions. The family is actively involved with treatment, and the individual begins association with Alcoholics Anonymous (AA) or Narcotics Anonymous (NA).
Table 3-5 Signs of Substance Abuse and Dependence
Controversy remains about the ultimate career path of the anesthesiologist in recovery. Within the general population, the recidivism rate approaches 60% for patients who have been treated for addiction. However, physicians are highly
motivated and better rehabilitation rates might be expected. Early reports provided optimism that in many cases anesthesiologists could be successfully rehabilitated and safely returned to their practices. In a study that examined relapse in addicted physicians, the rate of relapse among anesthesiologists was 40% and that of control physicians was 44%.126Sustained recovery for longer than 2 years occurred in 81 and 86%, respectively. Although these data suggested that the outcome for recovering anesthesiologists was similar to other physicians, a study by Menk and colleagues123 drew a different conclusion. Among 79 opioid-dependent anesthesiology residents, there was a 66% (52 of 79) failure rate for successful rehabilitation and return to practice. Even more discouraging, there were 14 suicide or overdose deaths among the 79 returning trainees. Their conclusion was that redirection into another specialty is the safer course after rehabilitation of narcotic-dependent residents. Using survey data from U.S. training programs, Collins et al124 found that only 46% of anesthesia residents treated for substance abuse successfully completed their anesthesiology training, 34% chose to enter a training program in another medical specialty, and 16% left medicine. There were 9 deaths among the 100 anesthesia residents that continued in anesthesia training programs after treatment.
Data from a retrospective study of health care professionals has identified three factors associated with relapse after completion of treatment for chemical dependency.127 Although the overall rate for relapse was 25%, the risk was increased when there was a family history of substance abuse (hazard ratio [HR] = 2.3) and when a major opioid was the abused drug in an individual with a coexisting psychiatric disorder (dual diagnosis, [HR = 5.8]). The risk of relapse was greatest (HR = 13.3) when all three factors were present, that is, family history, major opioid use, and dual diagnosis. Treated anesthesiologists who returned to the practice of anesthesiology had a greater risk of relapse (HR = 8.5) compared with those who did not return. Because of the small sample size, a more detailed analysis of risk factors for anesthesiologists could not be performed.
No universal recommendations can be made about re-entry into the practice of anesthesia after treatment. To re-enter practice, the recovering physician must qualify for a valid license to practice medicine and must be recredentialed at their medical facility. This must be done in compliance with their state laws and regulations that detail the circumstances under which a recovering physician can return to practice. Federal laws, such as the Americans with Disabilities Act, impose additional considerations. Additionally, a carefully worded contract is an important first step in the re-entry process to define the obligations of the physician and the department.114,128 Contracts usually include an agreement to refrain from self-prescription of medication, submit to random urine drug screens, and directly observed administration of naltrexone or disulfiram for at least 6 months. There should also be regular meetings with the departmental supervisor to monitor the return process. It is also generally recommended that the returning anesthesiologist not take night or weekend call or handle opioids without direct supervision for at least the first 3 months. Monitoring and treatment for an extended period is more likely to reduce the risk for relapse. Despite all of these precautions, the potential for relapse must be anticipated.
Guidelines from physician treatment centers may be helpful to assist in the decisions surrounding re-entry.111 Individuals who, in most situations, can successfully return to the practice of anesthesiology immediately after treatment (Category I) accept and understand their disease and have no evidence of accompanying psychiatric disorders. They have strong support from their family, demonstrate a balanced lifestyle, are committed to their recovery contract, and bond with AA or NA. Their anesthesiology department and hospital must be supportive of their return, and the individual must have a sponsor that supports the return to anesthesiology.
Category II includes those individuals who could possibly return to anesthesiology within a few years. They must have no or minimal denial regarding their disease and have no other psychiatric diagnoses. Their recovery skills are continually improving and they are involved, but not necessarily bonded, with AA/NA. Although their family situation may be characterized as dysfunctional, there should be tangible evidence of improvement.
Individuals who should not return to anesthesiology and would best be redirected into another medical specialty are included in Category III. These individuals may have had a history of prolonged intravenous substance use and have experienced relapses and prior treatment failures. Their disease remains active, and they have coexisting severe psychiatric diagnoses.
Impairment and Disability
Impairmentg and disabilityh can arise from physical, mental, emotional, sensory or developmental causes. The onset can be sudden, as occurs with injury or acute illness, or more gradual, as is the case with many chronic diseases.
Data regarding the prevalence of disabling disorders among physicians are difficult to obtain. Substance related disorders (see “Substance Use, Abuse, and Addiction”) occurs as frequently among physicians as in the general population113 (8% to 12%) and accounts for many cases of physician impairment.i It has been questioned whether, with the notable exception of opioid abuse, substance-related disease is more common among anesthesiologists than other physicians.124 However, unpublished data collected from one large insurance underwriter indicate that the rate of substance related disability among anesthesiologists is 3 times that seen among other physicians (personal communication, UnumProvident). Other factors that may lead to impairment include physical or mental illness and deterioration associated with aging. Unwillingness or inability to keep up with current literature and techniques can be considered a form of impairment.
Among physicians who are impaired as a result of emotional illness, depression is a prominent finding. In one study, approximately 30% of medical interns were clinically depressed.129Indeed, when exaggerated, many of the personality traits that ensure success in the physician's world, such as self-sacrifice, competitiveness, achievement orientation, denial of feelings, and intellectualization of emotions, may also serve as risk factors for depression. Several studies on alcoholic physicians have provided some insight into this link between achievement orientation and emotional disturbance. In one study, more than half of the alcoholic physicians graduated in the upper one third of their medical school class, 23% were in the upper one tenth of their class, and only 5% were in the lower one third of their class.130 Similarly, a report on alcohol use in medical school demonstrated better first-year grades and higher scores on Part I National Board of Medical Examiners tests among those students identified as alcohol abusers.131
It can be difficult to appropriately respond to the problems imposed by the impaired or unsafe anesthesiologist.132
Fortunately, many state legislatures and medical societies have formal protocols that address the impaired physician in a therapeutic and nonpunitive fashion. The license suspension power of the state board of medical examiners is usually exercised only in cases in which there is a substantial risk to the public welfare and the involved physician is unwilling to voluntarily suspend practice. Management protocols for dealing with the impaired physician are covered in a series of articles by Canavan and Baxter.133
The Aging Anesthesiologist
Little attention has been given to the challenges faced by older anesthesiologists.58 This is in contrast to the situation in most other industries in which much consideration is directed toward the competence and well-being of older workers. For example, commercial pilots are required to take regular medical examinations and conform to policies regarding hours of work.
Advancing chronologic age is predictably accompanied by changes in most organ systems. Most notable for the safe practice of anesthesiology are the changes commonly observed in the central nervous system. Neuronal density and brain weight decrease from 1,375 g at age 20 years to 1,200 g at age 80 years.134 There is an age related decline in training-dependent plasticity in the motor cortex accompanied by a diminished ability to reorganize in response to training.135
These and other anatomic changes are associated with common decrements in physiologic function. There are measurable decreases in hearing, vision, short-term memory, creative thinking and problem-solving abilities. Learning is slower and requires more effort. Intellectual quickness and on-the-spot reasoning and reaction time slow. These have the potential of adversely affecting the older anesthesiologist's ability to assimilate and apply new knowledge and to instantaneously process information, rapidly make complex decisions, and initiate the appropriate response.136 These deficiencies are especially exposed in a stressful environment such as the operating room.137
The cardiovascular and musculoskeletal systems also undergo age-related changes that can affect the ability to practice anesthesiology. One area of particular difficulty for anesthesiologists is maintaining the stamina required for long work shifts and night call. Superimposed on a propensity to sleep disturbance, the demands of night call and associated sleep deprivation are particularly difficult for older anesthesiologists. Night call is considered one of the most stressful aspects of practice and is often cited as a reason for retirement among older anesthesiologists.58,138
The physiologic changes that accompany the normal aging process are often compensated by advantages conferred by older age. These include wisdom, judgment, and the experience acquired by a lifelong practice of the specialty. There is a strong correlation between experience and performance.139,140 However, this correlation does not necessarily exist between experience and complex cognitive skills. As pointed out by Weinger,141 experience is not synonymous with expertise.
Aging among anesthesiologists raises interesting legal issues. There are no age-specific conditions placed on state medical licensure or on the practice of anesthesiology. In most cases, the decision to limit practice or retire remains at the discretion of the individual anesthesiologist based on his or her self-evaluation. A number of federal laws impact the aging anesthesiologist's rights and responsibilities regarding continuation of work. These include the Age Discrimination Act, Title VII of the Civil Rights Act (“Equal Pay Act”), the Medical and Family Leave Act, the Fair Labor Standards Act, and the Employee Retirement Income Security Act (ERISA).
Anesthesiology, similar to other high-stress professions, is commonly considered a young person's specialty. Anesthesiologists tend to retire at a younger age than do many other specialists.142 The decision to retire for an anesthesiologist is frequently precipitated by the growing burdens of night call or concerns about deteriorating clinical skills. In many cases, the retiring anesthesiologist just “felt it was time.”138 A growing number of practices are establishing phased retirement plans that permit senior anesthesiologists to avoid some of the more onerous aspects while remaining vital members of a practice.143
As a result of a number of demographic factors, including the smaller residency class sizes observed during the mid-1990s, the mean age of the anesthesiology workforce is increasing. The greatest number (30%) of anesthesiologists are between age 45 and 54 years of age, and 56% are age 45 and older (up from 49% 10 years ago).15
Mortality Among Anesthesiologists
A number of studies have examined mortality among anesthesiologists. Employing different databases and methods, these studies have reported conflicting conclusions including a shortened,14,144 an average,15,145 or a prolonged146,147 life expectancy. A 2006 study reported a significant increase in life expectancy among anesthesiologists during the last decade, such that the average age at death in 2001 (the last year of the study) was 78 years, the same as the national average for all Americans.148
The cause of death among anesthesiologists has also been extensively studied. Earlier work found an increased incidence of certain types of cancer, including leukemia and lymphoma.4,12 A more recent report by Alexander et al14 found no increased risk of cancer-related deaths among anesthesiologists as compared with the control group (internists). Significantly increased risks for anesthesiologists resulted from drug-related death, suicide, drug-related suicide, other external causes, HIV-related, and cerebrovascular disease. The risk to anesthesiologists of drug-related deaths was highest in the first 5 years after graduation from medical school and remained increased for entire professional careers.
It has been well documented that the rate of suicide ranks disproportionately high as a cause of death among both male149 and female150 physicians. Several reports have singled out anesthesiologists as being particularly vulnerable.14,147,151 However, this conclusion has been questioned as the result of the methodological difficulties in collecting accurate data on suicide and the frequent failure to adequately correct for confounding variables in the study populations.152
Why might there be a high rate of suicide among anesthesiologists? A partial explanation lies with the high degree of stress that is an integral part of the job.48 There is a close association in many individuals between stressful life events and major depressive disorders.153 In susceptible individuals, feelings of inability to cope resulting from the stress-induced depression can give way to despair and suicide ideation.
Extensive personality profiles collected from suicide-susceptible individuals indicate characteristics such as high anxiety, insecurity, low self-esteem, impulsiveness, and poor self-control. It is disturbing to note that in the study of personality traits of anesthesiologists by Reeve,154 some 20% manifested psychological profiles that reflected a predisposition to behavioral disintegration and attempted suicide when placed under
extremes of stress. This study raises the discomforting notion that “premorbid” personality characteristics exist before entering specialty training and are not being identified in the admissions process.
One specific type of stress, that resulting from a malpractice lawsuit, may have a direct causative association with suicide among physicians in general and anesthesiologists in particular. Newspaper reports have described the emotional deterioration and ultimate suicide of experienced physicians who have become involved in a malpractice suit. One study reported that 4 of 185 anesthesiologists being sued for medical malpractice attempted or committed suicide.151 Substance abuse among anesthesia personnel is another potential contributor to the increased suicide rate. Individuals with chemical dependence, who are not identified and are in the end stages of the disease, may die of drug overdose, a cause of death that can be difficult to distinguish from suicide. In one recent study, drug abuse was among the highest causes of death and the most frequent method of suicide among anesthesiologists.14 Drug overdose and death was the initial relapse symptom in 16% (13 of 79) of the parenteral opioid abusers who had re-entered their residency in anesthesiology.123 Physicians who are impaired from chemical dependence and whose privileges to practice medicine have been revoked are also at heightened risk for attempting suicide. Crawshaw et al155 reported 8 successful and 2 near-miss suicide attempts among 43 physicians placed on probation for drug-related disability.
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Editors: Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K.; Cahalan, Michael K.; Stock, M. Christine