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37 The impaired anesthesiologist – sleep deprivation
The Case
At 3 am, a first-year anesthesia resident was providing an anesthetic to a young adult male undergoing exploratory laparotomy for presumed appendicitis. The resident had started his shift 20 hours earlier at 7 am at this very busy county hospital. There were cases to follow and it was obvious that this resident would be busy until being relieved of duty the following day. As the case was finishing, the resident was drawing up medications to reverse neuromuscular blockade. He drew up 3 mg of neostigmine. He intended to draw up 0.6 mg of glycopyrrolate but instead drew up 30 mg of phenylephrine. The two drugs were in adjacent bins in the drug cart and were packaged in similar appearing vials. Prior to administering the likely lethal concoction, the resident described feeling that “something was not right.” Upon checking the empty vials on the anesthesia cart, the near miss was discovered and the syringe disposed of. The intended reversal agents were then drawn up and administered to the patient without incident. The resident completed two more cases during his call until being relieved the following morning. This incident was not reported to the residents’ supervisor. In three years of anesthesia training, this resident was offered the opportunity to nap on call only once by faculty.
The ASA Guidelines for the Ethical Practice of Anesthesiology outline the ethical responsibilities of anesthesiologists. Section IV.2 states:
The practice of quality anesthesia care requires that anesthesiologists maintain their physical and mental health and special sensory capabilities. If in doubt about their health, then anesthesiologists should seek medical evaluation and care. During this period of evaluation and treatment, anesthesiologists should modify or cease their practice.1
Sleep deprivation has a negative impact on performance, including the “special sensory capabilities” mentioned in the ethical guidelines. Anesthesia care providers are required to care for patients around the clock, presenting special problems for human physiology. Specific strategies have been used in other domains to mitigate the impairing affect of fatigue.
Human error
In 1999, the Institute of Medicine (IOM) published a treatise To Err is Human which uncovered a previously unappreciated level of patient mortality and morbidity associated with human error of health care providers.2 Although the IOM report did not specifically address the issue of care provided by sleep-deprived practitioners, it is likely that a fraction of the preventable errors that occur are secondary to this performance shaping variable. Error investigation in healthcare and in other industries has shown that fatigued workers make errors, although exact rates are difficult to quantify. Physicians are not able to withstand the impairing effect of sleep deprivation. Even though sleep deprivation and fatigue could not be proven to have contributed to the near miss in the case scenario, sophisticated accident investigation performed in other industries would conclude that it played a role.3
Basic sleep physiology
A basic primer in sleep physiology is important to understand the issues of sleep deprivation and its effect on performance. Sleep is a reversible behavioral state of perceptual disengagement from and unresponsiveness to the environment, and it is vital to human survival. It is comprised of two states – non-rapid eye movement (NREM) and rapid eye movement (REM) sleep that cycle throughout the night and can be differentiated electrophysiologically. Both NREM and REM sleep are required for optimal alertness, though the body will preferentially replete lost sleep with slow wave sleep (NREM stages 3 and 4). REM sleep is the stage when dreaming takes place. REM sleep periods get longer as the sleep period extends – the longest REM periods coming before awakening in the morning.
Physiologic sleepiness
Sleep is a basic human need similar to eating and drinking. When deprived of food or drink, we develop hunger or thirst. Similarly, if we obtain less sleep than we require, sleepiness becomes marked and our brain becomes “pressured” to acquire sleep –extreme sleepiness during hazardous activities can become manifest. In these situations the brain may shift uncontrollably between wake and sleep with little or no awareness from the individual. These short sleep episodes (called microsleeps or attentional failures) create safety risks especially when envisioning them occurring in the operating room during patient care or upon driving home after a long call period. This level of sleepiness occurs in all humans if pressed to extremes.
Subjective sleepiness
Subjective sleepiness (how sleepy we feel) often underestimates the level of physiologic sleepiness. It is conceivable that this subjective – physiologic disconnect makes critical decision making more challenging. This disconnect might help explain why the incidence of single vehicular automobile accidents is higher from 2–6 am, during times of increased physiologic vulnerability. Though we may think we are “OK” to perform, we are often less than optimally alert. The two primary determinants of sleepiness are modulated by sleep homeostasis and circadian rhythms.
The homeostat
Sleep homeostasis refers to the sleep–wake balance of an individual. This balance is a function of sleep need, offset by the quantity and quality of sleep obtained. An individual’s sleep propensity (i.e., sleep pressure) changes when this equilibrium is tipped in either direction. For example, if an individual’s sleep need is 8 hours per night but sleep achieved is 7 hours per night a sleep debt develops and sleep propensity increases. Average adults require greater than 8 hours of sleep per 24-hour period to maintain optimal alertness and function at peak levels. Population studies reveal that sleep need is normally distributed so that for every person who needs 6 hours of sleep for optimal alertness another will require 10 hours. Importantly, humans are notoriously poor at determining their true level of sleep need.
An individual’s sleep need is genetically determined and cannot be trained. As adults age, sleep need remains constant but obtaining adequate quantity and quality of sleep becomes more difficult. Sleep disorders increase with age and other benign issues associated with aging (e.g., urinary frequency in males and menopausal symptoms in females) make sleep consolidation increasingly difficult.
The circadian pacemaker
A circadian pacemaker located in the suprachiasmatic nucleus of the brain governs alertness. Humans are programmed for two nadirs of alertness between 2–6 am and 2–6 pm and these times represent periods of increased vulnerability to performance impairment due to pacemaker-induced sleepiness. The circadian clock is very resistant to alterations and does not adjust rapidly. For healthcare providers, the clock’s resiliency to change is best evidenced by those who work the night shift. It is often difficult to maintain alertness during the night when the body’s clock is “turned off” and similarly it is difficult to gain adequate sleep during the day when clock is “turned on” (e.g., attempting to sleep during the day after an on-call period). Working in opposition to circadian physiology is necessary in the round-the-clock work of health care providers but it comes at the risk of decreased alertness.
Fatigue affects performance
Fatigue adversely affects performance.4 Examples include slowing of cognition, increased performance variability, and decreased motivation. The learning of new information slows, memory is impaired, and non-essential activities are neglected. Picture the fatigued anesthesiologist at 3 am after being awake for a number of hours trying to safely care for patients with these very real constraints of human physiology. These are precisely the special sensory capabilities alluded to in the ASA’s Guidelines for Ethical Practice, and are critical for safe provision of care.
Performance is proven to be altered in sleep-deprived physicians. The Harvard Work Hours, Health and Safety Group showed that reducing shift duration by interns from 30 to less than 17 hours decreased serious medical errors by 35.9%.5 Simulation research of anesthesiologists supports the findings that a clinician’s performance is negatively impacted by sleep deprivation and that increasing sleep (either by prioritizing or napping) can improve performance.6
A robust finding in similar studies is that mood is dramatically affected by sleep loss and fatigue. Negative moods (e.g., anger, depression, fatigue, tension) increase and positive moods decrease as sleep loss accrues.7 The impact of impaired mood on interpersonal interactions between health care providers and between providers and patients has been inadequately studied but is likely to have an overall negative effect.
Comparison of sleep deprivation to ethanol usage
Results of research correlating the affect of sleep loss and alcohol consumption are alarming. Dawson showed that after 17 hours of wakefulness that performance on a tracking task declined to a level of impairment equivalent to a blood alcohol concentration (BAC) of 0.05%.8 After 24 hours of wakefulness, the decline in performance was equivalent to a BAC of 0.1% – over the legal level for driving everywhere in the US. This amount of wakefulness is commonly seen in medical professionals who take “in house” call and creates a source for systemic latent errors thus increasing system vulnerability.9
A study comparing the effects of sleep loss and alcohol consumption on performance of a simulated driving task further supports the correlation.10 With increasing blood alcohol concentration, simulated driving performance became progressively impaired. Speed variability, and off-road events increased, while speed deviation decreased, the result of subjects driving faster. Wakefulness of 18.5 and 21 hours produced changes of the same magnitude as 0.05 and 0.08% BAC, respectively. Finally, wakefulness prolonged by as little as 3 h can produce decrements in the ability to maintain speed and road position as serious as those found at the legal limits of alcohol consumption.
Related posts:
Informed consent and the pediatric patient
The use of ethics consultation regarding consent and refusal
Revising the Uniform Anatomical Gift Act – the role of physicians in shaping legislation
Animal subjects research Part I: Do animals have rights?
Physician conscientious objection in anesthesiology practice
Opioid therapy in addicted patients: background and perspective from the US
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