Occupational health and safety in anesthesia
Occupational Health and Safety in Anesthesia
Historically, the greatest occupational hazard encountered by an anesthetist was the threat of a fire or explosion while using a potentially explosive anesthetic agent. Replacement with non-explosive agents has rendered this hazard virtually obsolete in modern anesthesia; but what hazards may be encountered by today's anesthetist? This session will consider workplace-related and personal hazards specific to anesthesia.
Workplace-related hazards in anesthesia
Chronic Exposure to Anesthetic Gases
Anesthetists spend more time in operating rooms than do most other group of health workers. These results in greater exposure to the risks of the operating room environment, such as the potential long-term effects of trace anesthetic gases.
During the 1970s and 1980s several studies suggested that a link existed between exposure to anesthetic agents and hepatic disease, reduced mental performance and reduced manual dexterity. Evidence also suggested a higher rate of spontaneous abortion among female anesthetists exposed to anesthetic gases while the incidence of congenital abnormalities in children of both male and female anesthetists was raised compared with controls. However, concerns about the methodology of these studies led to the conclusion that no clear evidence of a link existed.
In 1999, legal limits for environmental levels were published in the Control of Substances Hazardous to Health Regulations (COSHH) as doubts about potential adverse health effects persisted. Emphasis was placed on the need for control measures including good anesthetic practice, frequent changes of theatre air and gas scavenging. Despite these precautions atmospheric pollution will still occur in some clinical situations, for example inhalation induction, mask ventilation and leaks around uncuffed pediatric tracheal tubes
Occupational exposure to a range of pathogens represents a serious risk to anesthetists. The risk of transmission of blood-borne pathogens, such as human immunodeficiency virus (HIV) and hepatitis B and C, are well known, but occupational exposure also includes airborne pathogens such as tuberculosis. The risk of occupational infection with a blood-borne pathogen is proportional to three factors:
i. Number of exposures to infected blood or body fluids.
ii. Prevalence of patients carrying the pathogen within an anesthetists practice.
iii. Infectivity of a particular pathogen.
Many exposures to blood-borne pathogens result from a failure to follow recommended procedures for the safe handling and disposal of contaminated "sharps" or a failure to wear appropriate protective clothing and eyewear. For anesthetists, the most likely source of an occupational exposure is self-inoculation from a needle during the insertion and suturing of intravascular catheters, the injection of intradermal anesthesia or resheathing of used needles. Transmission may also occur after exposure to body fluids other than blood, including amniotic fluid, cerebrospinal fluid, pericardial fluid, pleural fluid, synovial fluid, unfixed tissues and organs, exudative fluid from burns or skin lesions, vaginal secretions and semen. As the infection status of most patients is unknown, the adoption of universal precautions for all patients is recommended. Because there are documented reports of transmission of HIV from infected patients to health care workers (including anesthesiologists), the Centers for Disease Control and Prevention have proposed guidelines that apply to all categories of patient contact. These universal precautions, which are equally valid for protection against hepatitis B or C infection, are as follows:
- Needle precautions, including no recapping and immediate disposal of contaminated needles.
- Use of gloves and other barriers during contact with open wounds and body fluids.
- Frequent hand-washing.
- Proper techniques for disinfection or disposal of contaminated materials.
- Particular caution by pregnant health care workers and no contact with patients by workers who have exudative or weeping dermatitis.
The risk of acquiring HIV after an occupational exposure to HIV-infected blood is low. Epidemiological studies have indicated that the risk for HIV transmission after percutaneous exposure to HIV-infected blood in health care settings is 0.3%. After a mucocutaneous exposure, the risk is 0.03% and if intact skin is exposed to HIV-infected blood there is no risk of HIV transmission. The minimum dose of contaminated blood needed to infect a human after an occupational exposure is unknown but several factors have been identified as types of exposure with significant potential to transmit HIV. If occupational exposure does occur, the site of exposure should be washed immediately with soap and water and the occupational health department informed. Post-exposure prophylaxis has been shown to be maximally effective if taken within an hour after an exposure, but benefit may remain if commenced up to 2 weeks after exposure.
B. Hepatitis B and C
Hepatitis B is highly infectious and the risk of transmission after occupational exposure is higher than for HIV. The incidence of seroconversion from a high infectivity carrier ( antigen positive) to a non-immune health care worker is up to 40% after exposure by percutaneous inoculation, depending on the magnitude of contact with the blood. An effective vaccine exists to prevent the transmission of hepatitis B and all anesthetists should ensure that they are up to date with their immunization schedule. A blood test is necessary to confirm immunity as the non-responder rate is 5–10% and boosters are required every 5 yr. Anesthetists in whom no antibodies are present and who suspect exposure to hepatitis B should be immunized passively with hepatitis B immunoglobulin and receive a series of three injections of hepatitis B vaccine. Prior vaccination with seroconversion eliminates the need for immunoglobulin.
Hepatitis C is also a blood-borne pathogen. The risk of transmission after a hepatitis C contaminated occupational exposure has been estimated at 2%.5 Chronic hepatitis develops in 85% of hepatitis C infections with 20% progressing to cirrhosis and 3% to hepatocellular carcinoma. A chronic carrier state may also develop. No vaccine exists but some institutions offer immune serum globulin as post-exposure prophylaxis.
The incidence of tuberculosis is increasing, both in isolation and in association with other conditions such as HIV. Part of this increase is because of the appearance of multidrug-resistant strains. Tuberculosis spreads by small (1–5 μm) droplets released when an infected person speaks coughs or sneezes. Factors implicated in the transmission of the bacillus to an anaesthetist include bronchoscopy, laryngoscopy, tracheal intubation, suctioning of the airways and mechanical ventilation. Probability of transmission is also related to the concentration of infectious droplets and duration of exposure. Strategies to prevent disease transmission include education to raise awareness; the use of appropriate protective clothing and personal respirators; limiting the number of personnel in contact with the patient and where possible delaying surgery until a patient is non-infectious. Anaesthetists who have experienced a high risk exposure should undergo a tuberculin test and if indicated undertake 6–12 months of chemoprophylaxis.
Lacerations and glass splinters when opening drug ampoules are a common occurrence. Where possible, plastic ampoules or plastic "ampoule snappers" should be used. Repetitive strain injury, previously associated with the holding of facemasks for prolonged periods, is increasingly rare after the introduction of the laryngeal mask airway. The first metacarpo-phalyngeal joint is the commonest joint to be affected by osteoarthritis in any dexterous manual employment. Hand ventilation, opening ampoules, drawing up and injecting drugs are all actions that predispose to the development of this condition.
The development of latex allergy is associated with repeated latex exposure. In health care workers this often involves the use of latex containing gloves. Responses range from irritant contact dermatitis, a delayed type IV reaction mediated by T-cells to IgE-mediated anaphylactic shock. Latex allergy is also associated with a history of atopy and allergy to certain foods such as bananas, kiwi fruits and avocado. The use of latex free products, hand washing after contact with latex containing products and educational programmes aim to reduce the prevalence of latex allergy.
Anaesthetists can be exposed to ionizing radiation from X-rays and to non-ionizing radiation from lasers. Although the dose after an individual exposure may be extremely small, repeated episodes may lead to cumulative exposure with potentially adverse health effects. The monthly cumulative dose of radiation measured in a trauma theatre has been shown to be undetectable and the annual radiation exposure calculated to be below the dose limit of 15 mSv yr-1 as recommended by the Ionizing Radiation Regulations.
Exposure to non-ionizing radiation from lasers may occur either through direct exposure or reflection. Resulting injuries include burns to the cornea and retina, destruction of the macula or optic nerve and cataract formation. The two most important methods of minimizing exposure are using proper barriers and maximizing the distance from the source of radiation. Lead glass partitions or lead aprons with thyroid shields are mandatory protection for all personnel working in an imaging environment. Protective eyewear is designed to filter out radiation produced by specific lasers while still permitting vision and should be worn at all times when lasers are in use.
Magnetic Resonance Imaging (MRI)
The hazards associated with MRI include exposure to an intense magnetic field, acoustic noise and the possible risk of hypoxia if quenching of a superconducting magnet occurs. The effects of these hazards may be minimized by remaining in the control room while the scan is taking place.
Intense magnetic fields can cause a projectile effect on ferromagnetic items; they must not be taken into the vicinity of the MRI scanner. Implanted ferromagnetic items such as aneurysm clips or pacemakers may move or malfunction with potentially fatal results and anaesthetists, other staff and patients must be screened for the presence of any such implants. There is no evidence for an accumulative harmful effect of strong magnetic fields, although temporary symptoms of nausea or vertigo from stimulation of the semicircular canals may occur; safe levels of exposure are recommended.
Acoustic noise is produced by the vibration of the switched gradient coils during MRI scanning and may exceed levels recommended by the Health and Safety Executive. Patients and staff remaining in the examination room must wear ear protectors during a scan.
Cryogens, usually liquid helium, are used to maintain the magnetic coils at superconducting temperature. "Quenching" is the rapid boil-off of the cryogen which may occur because of system failure, or if the magnetic field needs to be shut down rapidly. The resultant large volumes of gas should be safely vented to the outside atmosphere; however, if this is prevented, the rapid production of helium gas within the examination room could result in a hypoxic atmosphere.
Diathermy and Laser Smoke Inhalation
Inhalation of smoke and vapour generated by the use of surgical diathermy and lasers represents a potential hazard to anaesthetists. Surgical masks do not filter toxic gases nor trap particles <0.5
μm in diameter. The median diameter of particles produced in smoke plumes is 0.31 μm. Pulmonary lesions have been demonstrated in laboratory animals after inhalation of smoke from tissues treated with a carbon dioxide laser, and the smoke plume generated by diathermy has been found to contain carcinogens such as benzene. Other chemicals (e.g. toluene, styrene, carbon disulphide) have been identified in diathermy smoke and can cause corneal irritation, dermatitis, renal and hepatic toxicity and affect the central nervous system. Viable bacteria, human papillomavirus DNA and HIV proviral DNA have also been found in laser smoke under experimental conditions. Operator exposure can be reduced effectively by suction devices; their routine use is advisable.
The use of monitors and electrical equipments continually exposes the anaesthetist to electromagnetic fields. Adverse health effects resulting from this exposure are not well defined but there are reports that an increased risk of brain cancer, breast cancer and leukaemia occurs in populations exposed to electromagnetic fields. While the potential health hazards and safe upper limits of exposure remain to be determined, anaesthetists should aim to minimize their exposure.
Anesthesia is a high-risk medical specialty for drug addiction. Reasons for this include the stress of anesthetic practice, the easy availability of drugs with addiction potential, and curiosity aroused by a patient's euphoria after receiving opioids and sedatives. The likelihood of developing a substance abuse problem is increased by coexisting personal problems (eg, marital, financial difficulties) and a family history of alcoholism or drug addiction.
The voluntary use of mood-altering drugs is a disease. If left untreated, substance abuse often leads to death from drug overdose-intentional or unintentional. One of the greatest challenges in treating this illness is identifying the afflicted individual, since denial is a consistent feature. Unfortunately, changes evident to an outside observer are often both vague and late: reduced involvement in social activities, subtle changes in appearance, extreme mood swings, and altered work habits. Treatment begins with an intervention plan of enrolling the individual in a formal rehabilitation program. The possibility of retaining one's medical license and reentering the mainstream of practice provides powerful motivation. Some diversion programs report a success rate of approximately 70%. Long-term compliance often involves continued participation in support groups (eg, Narcotics Anonymous), random urine testing, and oral naltrexone therapy (a long-acting opioid antagonist). Effective prevention strategies are difficult to formulate but may include better control of drug availability and education about the severe consequences of substance abuse.
A study performed in the US and published in 2000 found that, between 1979 and 1995, the standardized mortality ratio for all causes of death in anaesthetists was 0.48, indicating an approximate 50% lower overall mortality rate for anaesthetists compared with the general population. However, compared with a control group of physicians, anaesthetists had an increased mortality risk attributable to suicide, deaths related to drugs, HIV, cerebrovascular disease and other external causes. A UK study published in 1987 comparing consultants in anaesthesia and those in five other hospital specialities found that retirements related to ill-health in male anaesthetists occurred at more than twice the expected rate (P < 0.001); amongst female anaesthetists, deaths in post were significantly increased (P < 0.001). The nature of the ill-health leading to early retirement and the causes of death were described.
Most studies support a higher risk of suicide in doctors when compared with other professionals. When compared with the general population, the relative risk of suicide for doctors is 1.1-3.4 for males and 2.5-5.7 for females. Evidence also suggests that anaesthetists are at higher risk of suicide when compared with other medical specialties; the relative risk of suicide was 1.45 (95% CI 1.07-1.97, P = 0.002) in anaesthetists when compared with physicians. Contributing factors include mental illness, personal difficulties, occupational work stress, substance abuse and ready access to material in order to accomplish suicide.
Stress is an inevitable factor in professional and personal life and can lead to negative health effects, both mental and physical. Moderate levels of stress are an important driving factor in optimizing performance, but prolonged and excessive levels of stress, coupled with inadequate coping mechanisms, can lead to decreased job satisfaction, impairment of decision making and even suicide. Individual personality type is a significant factor in the development of stress. Doctors tend towards a "type A" personality associated with insecurity of status, anxiety and time urgency and these individuals may be more susceptible to stress. Sources of frustration and conflict may originate from domestic or professional life but they rarely occur in isolation and are often interrelated. In 1995, a report found that 30% of anaesthetists felt stressed a lot of the time while 5% felt stressed all the time; 33% described themselves as severely stressed and 7% felt their stress was more than severe.13 The major sources of stress identified are listed in Chronic exposure to stress will lead to exhaustion, characterized by physical and emotional symptoms, mental dysfunction and, ultimately, "burnout". Stress has also been identified as a precipitating factor in the development of alcohol and drug misuse. The management of stress hinges on the recognition of its nature and causes, and an understanding of how individuals respond. Modifications to lifestyle can then be made before clinical skills become impaired.
Human physiology dictates circadian patterns of alertness and performance and includes a vital need for sleep. Sleep loss and disruption of circadian rhythm can lead to reduced attention and vigilance, poor memory, impaired decision making, prolonged reaction time and disrupted communications. Workload pressures, insufficient numbers of personnel and increasing complexity of procedures compound the problem for doctors. Many studies have shown that fatigue reduces medical task performance. ECG interpretation and intubation skills have been shown to be reduced among emergency room physicians working night shifts when compared with similar staff working day shifts, and fatigue was listed as a factor contributing to 2.7% of all critical incidents in the Australian Incident Monitoring Scheme. Fatigue-related incidents may occur as a result of the individual experiencing "microsleeps". These brief, uncontrolled and spontaneous episodes of physiological sleep may last seconds or minutes and the individual may not be aware of them. However, they can reduce performance sufficiently to create safety risks. Other factors exaggerating the detrimental effects of fatigue include hypovolaemia, hypoglycaemia, alcohol and drug use, poor general health and concomitant use of some prescription medications.
Strategies to Maintain Alertness
Chronic fatigue may also affect an individual's physical health. Peptic ulcer disease, which is more common in shift workers, and gastrointestinal dysfunction presenting as vague, non-specific abdominal symptoms have led some to believe in the existence of a "shift-work maladaptation syndrome". The incidence of cardiovascular disorders is increased in shift workers and appears to be related to the number of years of exposure. However, there is no conclusive evidence that sleep deprivation in shift work leads to chronic ill health.
Strategies to reduce fatigue-related incidents include relief planning, regular and rehearsed equipment checking routines, improved workplace design (including drug ampoule and syringe labeling protocols) and regulation of working hours. The implementation of the "New Deal" and European Working Time Directive has reduced the number of continuous hours worked by trainees with many moving to a shift pattern of working.