Concerns about possible toxic effects of occupational exposure to inhalation anesthetics have been expressed since their introduction into clinical practice. Investigations have included cellular research, in vitro and in vivo studies, and epidemiologic surveys. Specific focuses of the research have been whether or not occupational exposure to waste anesthetic gases is associated with cytotoxic and genotoxic changes, organ toxicity, adverse reproductive outcomes, impairment of psychomotor skills, or premature death.

Evidence exists to show that cellular damage can result from chronic exposure of cells to high concentrations of anesthetic gases in the laboratory.² However, it can be misleading to extrapolate data from studies in cellular cultures or experimental animals to the real-world experience of humans working in operating rooms. The reports regarding possible cellular injury from waste anesthetic gases are inconsistent. Several studies testing for chromosomal aberrations, sister chromatid exchanges, or changes in peripheral lymphocytes have found no evidence of cellular damage among clinicians exposed to the levels of anesthetic gases that are encountered in an adequately ventilated operating room.³ On the other hand, individuals who are exposed to high ambient concentrations of waste gases, such as in anesthetizing locations where there is inadequate ventilation or scavenging, may be subject to a dose-dependent increase in cytotoxic changes.⁴ Reports on cellular changes thought to result from waste anesthetic gas exposure are difficult to compare because of the inability to standardize other risk factors to which operating room personnel are exposed, such as radiation, long work hours, and stress. Most sources agree that occupational exposure to the low levels of anesthetics found in operating rooms with effective waste gas scavenging is not associated with significant cellular effects.⁵

Nitrous oxide exposure is a special situation.⁶ Nitrous oxide can irreversibly oxidize the cobalt atom of vitamin B₁₂ to an 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. At clinically utilized concentrations of nitrous oxide, this inhibition could result in anemia and polyneuropathy. As with the halogenated hydrocarbon anesthetics, these effects with nitrous oxide have not been demonstrated in operating rooms with effective waste gas scavenging.

Methyl methacrylate is commonly used in various surgical procedures. Known cardiovascular complications of methyl methacrylate in surgical patients include hypotension, bradycardia, and cardiac arrest. 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 HCW suffered significant lower limb neuropathy after repeated occupational exposure to methyl methacrylate.²⁹ Concentrations as high as 280 ppm have been measured when methyl methacrylate is prepared for use in the operating room. OSHA recommends use of scavenging devices in order to maintain an 8-hour TWA exposure to methyl methacrylate of 100 ppm.

Allergic reactions to volatile anesthetic agents and to some muscle relaxants have been associated with contact dermatitis, hepatitis, and anaphylaxis in individual anesthesiologists.³⁰,³¹ Analyses of sera from pediatric anesthesiologists exposed to halothane demonstrated an increased prevalence of autoantibodies to cytochrome P450 2E1 and hepatic endoplasmic reticulum protein (ERp58).³²
Despite the presence of these autoantibodies, only 1 of 105 anesthesiologists had findings of any hepatic injury. These data suggest that although autoantibodies may occur in anesthesiologists frequently exposed to volatile anesthetics, they do not appear to commonly cause 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 12%.³³

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.

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 must avoid all direct contact with latex-containing products. It is also important that coworkers wear non-latex or powderless, low latex-allergen gloves to limit the levels of ambient allergens.

Anesthesia personnel are at risk of exposure from both direct and indirect sources of ionizing radiation. Direct sources of radiation include exposure from the primary x-ray beam and leakage from other sites within the x-ray equipment. Indirect exposure results from scattered radiation reflected off surfaces such as tables, other equipment, and patient.

The biologic consequences of radiation exposure vary depending on age, gender, and specific organ site of exposure. The deterministic effects of radiation cause cell death and organ injury and are cumulative in a dose-related fashion. Common examples of deterministic injuries include skin damage, infertility, and certain types of cataracts. Stochastic effects of radiation are those that result in DNA injury and the development of cancer. There is no known threshold below which the risk of developing cancer completely disappears. And there can be a long latency period before the clinical presentation of an induced neoplasm.

OSHA has published occupational limits for workers exposed to ionizing radiation.³⁴ The annual limit is 5 rem with an allowable long-term limit of (N – 18) × 5 rem where N is the age in years. The recommended maximum occupational exposure to a declared pregnant worker should not exceed a monthly limit of 0.5 mrem or a total exposure of 5 mrem (excluding medical and natural background radiation).

Early studies found the exposure to radiation among anesthesia personnel to be safely below the OSHA limits.³⁵ However, more recent studies, conducted subsequent to the increased utilization of ionizing radiation in operating rooms, cardiac catheterization, and other interventional radiology suites, have revealed a worrisome trend toward increased exposure among anesthesia personnel (although still well below OSHA limits).³⁶,³⁷,³⁸ In one study, there was a doubling of the aggregate radiation exposure to members of a department of anesthesiology in the year following the introduction of an electrophysiology laboratory³⁸ (Fig. 3-1). Anesthesia personnel in this study increased their average exposure to almost 500 mrem on an annualized basis. Preventative strategies for anesthesiologists to minimize their risk of radiation-induced injury include limiting the intensity and exposure time, distancing oneself from the source of the radiation, and using maximal shielding from both primary and scattered sources of radiation.

A second form of radiation with potential health hazards comes in the form of chronic exposure to low-frequency electromagnetic
fields such as those emitted by MRI equipment.³⁹ It is often necessary for the anesthesia care provider to remain in close proximity to the patient, and thus the magnet core, during MRI studies. Data are not yet available to determine the safety of long-term exposure to high-intensity magnetic fields. Therefore, until such time that safety thresholds have been determined for this type of exposure, anesthesiologists should obey the general admonition regarding all radiation exposure. That is, keep exposure as low as reasonably achievable.

Noise is quantified by determining both the intensity of the sound and the duration of the exposure. OSHA has determined that the maximum level for safe noise exposure is 90 dB for 8 hours.⁴⁰ 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.

Noise levels in a modern operating room frequently exceed OSHA limits and are a potential health hazard. Ventilators, suction equipment, music, and conversation produce background noise at a level of 75 to 90 dB. Superimposed on these are sporadic noises caused by dropped equipment, surgical saws and drills, and alarms. Resultant noise levels can exceed 100 dB over 40% of the time with peak levels in excess of 120 dB, which is comparable to the clamor of a busy freeway or a rock and roll band ⁴¹ (Table 3-3).

Excessive levels of noise can adversely influence an anesthesiologist’s capacity to perform common clinical tasks. Mental efficiency, short-term memory, and ability to multitask and perform complex psychomotor tasks are all diminished by exposure to excess noise.

Noise also interferes with the ability to hear alarms. This is especially apparent in the magnetic resonance imaging suite where noise from the scanner can mask many anesthesia alarms. Similarly, excessive noise can interfere with crucial verbal communication. Voice levels must be at least 20 dB above background noise to be heard and understood.

There are also chronic health ramifications of long-term exposure to excessive noise. Chronic exposure has been associated with elevated levels of endogenous catecholamines and heightened levels of stress, increased irritability, and elevated blood pressure.

Ultimately, exposure to excessive noise levels will result in hearing loss. Although no direct connection has been established with excess noise experienced in the operating room, it is interesting to note that more than 50% of anesthesiologists have a substantial hearing deficit and 7% have deficits that potentially interfere with their ability to hear operating room alarms.⁴²

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.⁴³ Self-selected background music can contribute to reducing autonomic responses in surgeons and improving their performance.⁴⁴ The beneficial effects are less pronounced when a third party chooses the music. The selection of music, and the volume at which it is played, should be determined by mutual agreement of all parties present in the operating room.

Human factor analysis, also called ergonomics, is the study of the interaction between humans and machines and the impact of equipment design on their use. It is a multidisciplinary science that applies diverse disciplines such as anthropometry, ethnography, biomechanics, industrial and social psychology, architecture, education, and information technology, toward developing user-friendly equipment and a safer workplace.

Human factor analysis has been most widely employed in industries such as aviation, nuclear power, and oil exploration where human error frequently has contributed significantly to catastrophic accidents. The work performed by an anesthesiologist shares many of the characteristics found in these industries, including the intricacy of the tasks, a narrow margin of error, and the vulnerability to human error.

A number of human factor difficulties exist in the anesthesiologist’s workplace. For example, anesthesia equipment is often poorly designed or positioned. Anesthesia monitors are frequently placed so that the anesthesiologist’s attention is directed away from the patient and surgical field. This was well demonstrated by observations that the insertion and monitoring of a transesophageal echocardiograph probe added significantly to the anesthesiologist’s workload and diverted attention away from other patient-specific tasks.⁴⁵

The ability to sustain complex monitoring tasks, such as maintaining vigilance,^a and to respond to critical incidents 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. 3-2).

Vigilance tasks are generally performed at the level of 90% accuracy. In a setting where the stakes are high, such as during anesthesia and surgery, this leaves an unacceptable margin of error. 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.

A number of other work place factors conspire to interfere with anesthesiologists’ ability to perform their complex tasks. Even seemingly trivial aspects of an anesthesiologist’s work that require the expenditure of excessive energy produce a decrement in performance 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 a result of the ever-increasing number of monitors to be observed and amounts of data to be processed during the course of a surgical procedure, larger amounts of mental work must be expended. The cognitive burden varies directly with the difficulty encountered in extracting information from the monitors and displays that compete 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 augmenting 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 susceptible to many artifacts and false positives that can cause “alarm fatigue” and distract the observer from more clinically significant information. It is not unusual for distractive alarms to be ignored or inactivated.⁴⁶ A positive trend that is emerging in alarm technology is the development of “knowledge-based alarms” that can integrate information from more than one monitor and suggest a list of diagnostic and therapeutic possibilities.

Organizational issues, such as failed communication among team members, can adversely impact an anesthesiologist’s performance. The potential for disaster as a result of poor communication has been well illustrated in a number of airline catastrophes. 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 absence of a well-defined hierarchical organization with overlaps in areas of expertise and responsibility. Poor communication can lead to conflict and compromised patient safety and has been identified as a root cause of many anesthesia-related sentinel events.

Effective conflict resolution is an important element of the teamwork 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. Some degree of conflict occurs during the management of as many as 78% of patients in high-intensity areas such as operating rooms or critical care units.⁴⁷

Successful resolution of conflict is a skill that can be learned.⁴⁸ Mutual respect is required among team members along with a willingness to carefully listen and recognize differences of opinion. Intervention by a neutral third party is frequently helpful in finding an innovative solution. The airline industry has successfully implemented crew resource management programs to improve the performance of cockpit teams.⁴⁹

“Production pressure” is an organizational concern that has the potential to create an environment in which issues of productivity supersede those of safety.⁵⁰ 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. It appears to be particularly suited to training nontechnical skills such as resource management, teamwork, and communication.⁵¹

A circadian pattern of alertness and sleep is a fundamental element of healthy human physiology. Inadequate sleep caused by any number of factors, including obstructive sleep apnea or disruptive work schedules, can contribute to adverse health effects including cardiovascular disease and psychological illness such as irritability, displaced anger, depression, and anxiety. Individuals who suffer from sleep deprivation also think and move more slowly and make more mistakes.

Sleep loss and fatigue can have deleterious effects upon work practices. In general, workers who are sleep deprived suffer a decrement in performance and are at greater risk of committing workplace errors. Fatigued individuals are more susceptible to “microsleeps” which are brief, uncontrolled, and spontaneous episodes of physiologic sleep that may last as little as a few seconds. Fatigued workers also incur more work-related accidents.⁵² The susceptibility to accident is not limited to work hours and
extends to other activities of daily living, such as driving. The changes resulting from sleep deprivation bear a striking similarity to that seen with alcohol intoxication.⁵³ Significant individual variations in impairment due to fatigue have been identified.⁵⁴

The contribution of sleep loss and fatigue to accidents has been well documented in many well-publicized industrial catastrophes. Sleep deprivation was a contributing factor to industrial accidents such as those that occurred at Chernobyl, Three Mile Island, Exxon-Valdez, and the Challenger space shuttle catastrophe.

A number of reports have also identified sleep deprivation as a causative factor in errors occurring in the health-care industry.⁵⁵ As early as 1971, Friedman et al. reported that interns made almost twice as many errors reading electrocardiograms after an extended work shift than after a night of sleep.⁵⁶ Intubation skills were reduced among emergency room physicians working night shifts when compared with other staff members working days.⁵⁷ Physicians in both groups were more likely to commit errors during a simulated triage test toward the end of their work shifts. And in a study that examined the management by medical interns of medical admissions, 35.9% more medical errors were committed while on a “traditional” schedule (24 hours plus work shifts) than when they worked a schedule that eliminated extended work shifts and reduced the number of hours worked per week.⁵⁸ Mistakes committed by these interns included 20.8% more medication errors and 5.6 times as many diagnostic errors.

Anesthesiologists who take night call commonly suffer from each of the three well-defined classes of sleep deprivation: Total, partial, and selective sleep deprivation. Interruption of sleep during call commonly occurs between the hours of 2 AM and 4 AM when humans are most vulnerable to fatigue-induced errors.

A number of specific consequences of sleep deprivation have the potential to adversely impact the conduct of a safe anesthetic, including impaired cognition, short-term memory and clinical decision making, prolonged reaction time, and reduced attention, vigilance, and performance. In a report by Howard et al.,⁵⁹ sleep-deprived residents managing a 4-hour simulated anesthetic demonstrated progressive impairment of alertness, mood, and performance and had longer response latency to vigilance probes.

Performance after sleep deprivation does not return to normal levels until 24 hours of rest and recovery has occurred after a period of sleep deprivation. Residents in their routine, non-post call state continue to suffer from chronic sleep deprivation and have the same degree of sleepiness as measured in residents finishing 24 hours of in-house call.⁶⁰

An interesting phenomenon is the “end-spurt,” in which previously deteriorated performance shows improvement when the subject expects that the task is nearly completed. However, if the procedure is unexpectedly prolonged, a “let-down” occurs with additional deterioration in performance.

Despite adequate evidence of performance impairment due to fatigue, the precise role of sleep deprivation on the specific end point of clinical outcomes remains unclear. A number of studies have reported a detrimental effect on patient outcomes of sleep deprivation among providers. In two studies of American anesthesia caregivers, more than 50% reported having committed an error in medical judgment that they attributed to fatigue.⁵⁰,⁶¹ And 58% of New Zealand anesthesiologists reported that they had exceeded their self-defined limit for safe continuous administration of anesthesia and 86% reported that they had committed a fatigue-related error.⁶² Similar reports of fatigue-related complications appear in the surgical literature with as many as 16% of preventable adverse surgical events attributed to surgeon fatigue.⁶³,⁶⁴ However, others have reported no evidence of suboptimal clinical management or poor outcomes from sleep-deprived clinicians. Chu et al. found no increase in mortality or major complications in 4,000 consecutive cardiac surgical procedures performed by surgeons who had varying degrees of sleep (ranging from 0 to >6 hours) the night before surgery.⁶⁵ Other studies of surgeons and critical care specialists have agreed with these findings.⁶⁶,⁶⁷

Several factors help to explain the apparent disparity between reports of fatigue-related performance impairment and the failure to conclusively link these with medical errors or adverse outcomes. The distinction between sleep deprived and well rested is often arbitrarily defined with varying definitions of the non-rested state. For example, in one study the general conclusion was that there were no overall difference in complication rates between surgeons who had operated during the previous night (“post-nighttime”) and rested surgeons.⁶⁸ However, when sleep patterns were stratified, there was a substantially elevated rate of complication (6.2% vs. 3.4%) if the surgeon had less than 6 hours sleep during the on-call night. Also, there is great difficulty in eliminating confounding variables such as the impact of loss of continuity of care, errors that can occur during “hand-offs” of critically ill patients, and the reallocation of many medical tasks from physicians to nonphysician providers. Finally, it can be difficult to extrapolate findings from simulation studies of volunteers in a laboratory to clinicians in real-life work conditions.

Medicine remains significantly behind other industries, most notably the transport and airline industries, in identifying and regulating work practices that permit excessively long shifts. It was not until the well-publicized Libby Zion case in 1984 (in which it was charged that fatal, avoidable mistakes were made by exhausted, unsupervised residents) that medical organizations and state legislatures took action to limit excessive work hours among residents. In 2000 the Accreditation Council for Graduate Medical Education (ACGME) established the first set of standards to limit resident duty hours. These standards were revised by the ACGME in 2011.⁶⁹ Policies established by the ACGME include the following:

Somewhat ironically, at the end of a long list of duty hours restrictions, item VI.G.5.a-c states, “Residents in the final years of education (as defined by the Review Committee) must be prepared to enter the unsupervised practice of medicine and care for patients over irregular or extended periods.” This statement recognizes that these restrictions on duty periods apply only to trainees and that work hours in medical practice remain unregulated.

Prolonged work hours and sleep deprivation are a ubiquitous component of many anesthesiologists’ professional lives. Many academic faculty members now work longer hours than they did prior to house staff work hour limitations because of the shift of work from residents to faculty. Attending anesthesiologists and nurse anesthetists commonly work 10- to 12-hour workdays and 24-hour on-call shifts. Gravenstein et al. reported that the average anesthesiologist’s work week was 56 hours and that 74% of the respondents had worked without a break for longer periods than they personally thought was safe.⁶¹

Several strategies have been devised to reduce fatigue and limit the adverse effects of sleep deprivation when long work periods are necessary. Recommendations include minimizing sleep debt by maximizing sleep before on-call shifts and utilizing maneuvers to overcome sleep inertia such as increasing ambient light levels and stretching, taking frequent breaks, and napping when possible. A number of pharmaceutical aids, such as caffeine and modafinil (a schedule IV drug), have been approved for military use and, if used under supervision and carefully monitored, arguably may be helpful for clinicians with shift-work sleep disorder.⁷⁰

In the late 1980s the CDC formulated recommendations (“universal precautions”) for preventing transmission of blood-borne infections to HCWs. The guidelines were based on the epidemiology of Hepatitis B Virus (HBV) as a worst-case model for transmission of blood-borne infections and available knowledge of the epidemiology of HIV and Hepatitis C Virus (HCV). Since asymptomatic carriers of many blood-borne viruses cannot 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 pathogens, it was recognized that universal precautions should also be applied to semen, vaginal secretions, human tissues, and cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids. Subsequently, the CDC synthesized the major features of universal precautions into “standard precautions” that should be applied to all patients⁷⁷ (Table 3-4).

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 may be all that is necessary during many procedures that involve contact with mucous membranes or oral fluids, such as during routine endotracheal intubation or during insertion of a peripheral intravenous catheter. However, additional personal protection, such as gown, mask, and face shield, may be required during endotracheal intubation when the patient has hematemesis or during bronchoscopy or endotracheal suctioning. Respiratory hygiene/cough etiquette 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.⁷⁸ These standards require 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. Among other requirements, the employer must encourage strategies to reduce blood exposures, furnish appropriate PPE (e.g., gloves, gowns), offer the HBV vaccine at no charge to personnel, and provide an annual educational program to inform employees of their risk for blood-borne infection.

Implementation of standard precautions and OSHA regulations has been effective in decreasing the number of exposure incidents that result in HCW contact with patient blood and body fluids.

The institution’s employee health service is required to obtain and record a contagious disease history from new employees and provide immunizations and annual purified protein derivative (PPD) skin testing. In addition, the employee health service must have protocols for dealing with workers exposed to contagious diseases and those percutaneously or mucosally exposed to the blood of patients infected with HIV or hepatitis B or C virus. Free consultation is available from the CDC Postexposure Prophylaxis Hotline (PEPline) at 1-888-HIV-4911. Protocols are also needed for dealing with caregivers who have common contagious diseases and for those who have less common but high-visibility public health problems.

Respiratory viruses account for half or more of all acute illnesses and are usually transmitted by one of two routes. First, small-particle aerosols from viruses such as influenza and measles are produced by coughing, sneezing, or talking and can be propelled over large distances. Second, large droplets that have been produced by coughing or sneezing can contaminate the donor’s hands or an inanimate surface. The virus is then transferred to the oral, nasal, or conjunctival mucous membranes of a susceptible person by self-inoculation. Rhinovirus and human respiratory syncytial virus (HRSV) are spread by this process.