Hospital administrative responsibilities must guarantee 24-h patient treatment and care. On the one hand, the legal regulations on hospital employment determine maximum tolerable work-time per week, while long work-hours including night duties with limited and often-interrupted sleep are frequently routine for medical personnel [1,2]. Shift work is known to affect physiological systems, cause circadian rhythm disruption and contribute to the occurrence of psychosomatic disease . Chronic stress and fatigue favour the development of exhaustion with professional dissatisfaction and poor work-performance [3,4]. In particular, anaesthetists are regarded as a special risk-group for excessive labour and burnout [5,6]. Continued sleep deprivation may alter mood and motivation and decrease cognitive and psychomotor performance . It may increase attention failures by reducing peak mental abilities and response times [8,9] and, ultimately, fatigue may contribute to severe medical errors that affect patient safety [10–12].
In recent years legislation limiting the number of work-hours has been passed in an attempt to prevent possible diminished performance on the part of overworked physicians and thus guarantee the quality of patient care [10,12]. Both in the USA and in Europe (i.e. Switzerland), senior staff members were exempted from these protective provisions. This also gave rise to fear that the work of the junior physicians would in future have to be taken over by the senior physicians and thus an age-dependent decline in performance could drop still further . The implementation of these, for the senior physicians, disadvantageous provisions is all the more surprising, because previous work has shown that ‘demands of workload’, ‘burnout’ and ‘demands of night duties’ are the most frequently cited reasons for retirement [13,14]. Regardless of a person's occupation, it is commonly accepted that biological aging reduces occupational performance, with this reduction in performance being aggravated by stressors [13,15]. We thus attempted to determine whether the performance of senior anaesthetists is significantly reduced as compared to that of younger colleagues after completion of a 24-h work shift.
Materials and methods
An observational comparative working place study was conducted in 11 senior anaesthetists and 12 trainees of anaesthesiology at the University Department of Anaesthesiology and Critical Care Medicine, Innsbruck Medical University, Austria. The objectives of the study were to evaluate the effects of sleep deprivation on concentration abilities and well-being in senior anaesthetists. The study was approved by the authors' institutional human-investigation committee. Written informed consent was obtained from all subjects. Participation was voluntary in this investigation and was based on the understanding that data privacy would be protected and results published in medical journals. Senior anaesthetists at an age of 50 (range: 47–53 yr) and junior anaesthetists at an age of 30 (range: 27–33 yr) were enrolled. Participants were evaluated twice, namely before and after on-call duty, and served as their own control. Investigations were carried out on randomly assigned weekdays from May to June 2004. At the beginning and after 24 h of in-house duty (8-h day shift and 16-h on-call duty) all participants underwent a battery of psychometric tests.
Day shift was defined as all clinical activities, administrative duties and teaching work during light hours of day work. In-house on-call duty was defined as the duty hours beyond the routine workday and requiring the immediate availability of the anaesthesiologist. According to the Austrian law governing hospital working-conditions duty periods are restricted to a maximum of 24 consecutive hours.
Assessment of tiredness and concentration abilities
Degree of tiredness and concentration abilities were assessed by applying a visual analogue scale (VAS) to measure the proband's subjective perception of current state . Endpoints on a 100-mm scale were defined as 0: no tiredness and 100: maximum tiredness. Stress during night duty was rated by respondents using a four-point scale that went from 1: calm to 4: very demanding. Overall sensitivity for VAS was reported 90% and specificity 44% .
A questionnaire was provided for the self-assessment of well-being after duty. Total hours of sleep, number of sleep interruptions and consumption of cigarettes, coffee and tea were investigated.
Assessment of fatigue and burnout
A simplified German version of the Maslach Burnout Inventory (MBI-D) was applied to assess features of burnout . The MBI-D includes 25 items and addresses four general scales:
- emotional exhaustion (nine items), defined as feelings of emotional overextension,
- depersonalization (five items), defined as negative cynical attitude,
- lack of personal accomplishments (eight items), the tendency to experience loss of competence,
- consternation (three items), defined as fear resulting from awareness of being susceptible to harm.
Participants responded on a five-point scale that ranged from 1 (never) to 5 (very often) to measure the frequency of feelings they experienced. Each proband completed the questionnaires once after duty.
Psychometric testing was applied to measure level of vigilance, ability to concentrate and perform complex motor-tasks in probands. The choice reaction time task was used as an indicator of sensorimotor performance, assessing the ability to attend and respond to a critical stimulus . Subjects positioned their index finger on a central button and were instructed to extinguish one of six equidistant red lights, illuminated at random, by moving to and pressing the corresponding response button as quickly as possible.
Recognition reaction time was defined as the time between stimulus onset and the subject lifting their finger from the start button measured in milliseconds (ms).
Motor reaction time was the time between the subject lifting their finger from the start button and touching the response button.
Total reaction time was calculated as the sum of recognition and motor reaction times.
Critical flicker fusion was used to assess arousal and individual integrative capacity. Subjects had to discriminate between flicker and fusion in a set of four light-emitting diodes at a distance of approximately 1 m. A decrease in the threshold frequency in hertz (Hz) was regarded to indicate a reduction in the overall integrative activity of the central nervous system . Compensatory tracking-tasks were applied as an interactive test of psychomotor function that entails tracking a moving target on a visual display with the help of a joystick.
Response measure was the mean deviation from the track programme over a 1-min trial period; lower scores indicated more accurate tracking.
Peripheral awareness task – recognition time was measured, in which the subject had to respond to a stimulus presented in the periphery of vision, while still attending to the tracking task .
Mean differences between pre- and post-duty scores of continuous variables were computed with nonparametric t-test as far as the variables were normally distributed and the variances were homogenous. A U-test was used for ordinal data to analyse differences between groups. All statistical tests were two-tailed. P-values <0.05 were considered to indicate statistical significance.
Participants. A total of 23 anaesthetists were studied to objectively quantify vigilance and psychomotor performance after having worked a 24-h in-house on-call duty. These were 11 specialists in anaesthesiology at a mean age of 49.0 ± 2.0 yr and 12 trainees at a mean age of 29.7 ± 1.0 yr (Table 1). The response rate of senior anaesthetists was 84.6%. Male anaesthetists were preponderant (69.6%); the gender distribution was representative for the age groups.
VAS self-assessed tiredness and concentration abilities. The self-assessed degree of pre-duty tiredness was high in both groups but did not differ significantly. The corresponding pre-duty values for concentration abilities did not differ either. Self-assessed tiredness significantly increased and concentration abilities decreased in senior anaesthetists after duty (Table 2). Post-duty assessment revealed significant reduction of concentration abilities in both groups, but distribution of mean values indicate a tendency towards higher reduction in concentration abilities in senior anaesthetists compared to junior anaesthetists (Tables 2 and 3). Total sleep time during night duty was low in both groups. Senior anaesthetists slept on average 4.14 + 1.7 h per duty. Interruptions per night duty due to being called to work occurred more frequently in older anaesthetists (P = 0.05) (Table 4). Coffee, tea and nicotine consumption were comparable in both groups.
Psychometric test battery. A battery of psychometric tests was administered before and after duty. Testing including recognition reaction time, motor reaction time, total reaction time, critical flicker fusion, peripheral recognition time and response measure showed no significant differences in pre- or post-duty assessment between the two age groups (Table 3). There was, however, a tendency towards prolonged reaction time in pre- and post-duty assessment as measured by response reaction time in senior anaesthetists (Table 2).
MBI-D and post-call risk of accident. Assessment of burnout using MBI-D did not reveal significant findings in personal accomplishment, depersonalization or emotional exhaustion in senior anaesthetists. Frequency of consternation was low in both age groups. In addition junior anaesthetists showed a significant lack of personal accomplishment as compared to their older colleagues (Table 4). Analysis of individual MBI-D items showed significant differences between the age groups with regard to self-assessment of contribution to patient well-being. Senior anaesthetists more frequently emphasized the social aspect of their work (‘I feel I can positively influence the life of other people with my work’; P = 0.035) and their own ability to solve their patients' problems (‘I am rather successful in handling my patients' problems’; P = 0.022). There were significant differences in personal assessment of work sensitivity between senior anaesthetists and younger anaesthetists (‘I can easily put myself into my patients' shoes’; P = 0.044).
One senior anaesthetist admitted to drive home regularly by car after duty. When asked how many road traffic accidents they had had within the last 2 yr on the day after night duty, three younger anaesthetists reported accidents. One of them had even had two accidents in 2 yr following night duty.
A comparative, self-controlled study of psychomotor abilities in younger and older anaesthetists was conducted. Our data reveal that self-assessed performance by both junior and senior anaesthetists is markedly diminished after 24 h of in-house on-call duty. Although senior anaesthetists reported a subjective decline in concentration abilities in our investigation they did not show relevant differences in psychomotor parameters between the age groups.
Anaesthesiology is commonly viewed as a speciality practized by young employees. In a 1999 study on the effects of age on professional development more than two-thirds of the interviewed anaesthetists were between the age of 30 and 49 yr . Possible differences in performance between the age groups were generally anticipated to the detriment of the older doctors, but a mail survey surprisingly showed that young anaesthetists at an age of 30–39 yr reported significantly more mistakes, fixation errors, more problems with environmental distractions, as well as recent drops in fine-motor skill, short-term memory and vigilance as compared to older colleagues at an age of 40–49 and 50–59 yr [5,14].
Degree of pre-duty tiredness was high in both groups and the total sleep-hours per anaesthetist were low for on-call duties in our investigation. This makes a deficit of approximately 3 h to their normal sleep hours during off-duty nights not taking into consideration the presumptively lower quality of rest during on-call duties. In addition, senior anaesthetists more frequently reported sleep interruptions while on-call. Tiredness prior to duty can result from individual lifestyle or family conditions but could also indicate inadequate recuperation between duty shifts . Out-of-hospital activities were not reported.
In terms of their typical job burden, anaesthetists are occasionally compared to pilots . The Federal Aviation Administration's ‘Age 60 Rule’, however, has recently been critically questioned, because a critical analysis of older pilots showed no higher frequency of incidents . Our study showed a trend towards a higher degree of tiredness and a reduction in concentration abilities after duty in senior anaesthetists. This is concordant with findings published by Harma and colleagues, who reported that aging decreases the ability to recover after several night shifts . In a competitive environment the admission of tiredness for whatever reason might indicate weakness or lack of competence. Fatigue/tiredness may be attributed to advanced age and induce fear of failure, and senior anaesthetists might regard earlier development of tiredness as a sign of age-dependent reduced personal fitness. They might be under pressure to perform, especially when compared to younger residents.
The stress level experienced by physicians as compared to that experienced by the general population is rated differently in medical literature [1,25]. A longer-lasting imbalance between psychological and physical burden, and personal ability to cope with stress favours the development of exhaustion, which enhances risk acceptance and subsequently compromises the anaesthetist's own and the patient's safety [3,26]. On the other hand lack of personal accomplishment in younger anaesthetists can be interpreted as limited competence but in contrary to Martin and colleagues  and Kluger and colleagues  emotional fatigue and depersonalization typical of burnout syndrome, were not detected in our study. The chance for a motor vehicle accident to occur after an extended work shift was reported to be more than double in a study by Barger and colleagues . In addition to the increased risk for accidents when driving home, insurance companies may refuse payment whenever there is evidence of insufficient rest prior to driving.
Aging is associated with progressive deterioration in mental, physical and behavioural functions although there is growing experience and enhanced capacity for reasoning . There is still the possibility of compensatory strategies that can be used to maintain performance in psychometric testing, that do not allow the assessment of limited performance during work . Our study did not show relevant differences in psychomotor parameters between the age groups. Furthermore, older anaesthetists appeared to have a higher opinion of their contribution to patient health than did their younger colleagues.
Limitations on the interpretation of results stem from the fact that despite post-duty repetition of psychometric testing the number of investigations is low. Although about 85% of senior anaesthetists in the susceptible age group were enrolled, distribution bias cannot be completely excluded. In addition, there is the chance of selection bias regarding senior anaesthesiologists who survived the more competitive working conditions of a university hospital. The study does not have adequate power for including. This investigation, however, could serve as a pilot study for a national survey. Secondly, age is not the only criterion that determines the professional fitness of senior colleagues. Furthermore, fatigue/tiredness may be regarded as the employee's own fault and may even be rewarded with annoyance and intolerance by colleagues. In a system of competition and dependency, there is always the possibility that information is held back in a questionnaire. Thirdly, in the Austrian health care system senior anaesthetists are frequently busy with administrative obligations and commonly act as back-up specialists. This explains in part the longer-working times as compared to younger colleagues. As the total number of duties per month is not that high, out-of-hospital activities might play an additional role in some of the anaesthetists. Employers have to be aware of cumulative work-arrangements of their employees. Finally, standardized tests do not adequately address problems with short-term memory, concentration, as well as language and word-finding difficulties after duty.
In conclusion, our study provides data on the evaluation of pre- and post-duty performance in anaesthetists. Pre-duty tiredness was prevalent in both age groups, the level of performance after 24 h of in-house on-call duty in senior specialist and in anaesthesiology trainees, however, did not show striking differences. The results of our study do not support the hypothesis that performance by senior anaesthetists is less than adequate.
1. Winslow ER, Bowman MC, Klingensmith ME. Surgeon workhours in the era of limited resident workhours. J Am Coll Surg
2. Murray D, Dodds C. The effect of sleep disruption on performance of anaesthetists – a pilot study. Anaesthesia
3. Kuhn G. Circadian rhythm, shift work, and emergency medicine. Ann Emerg Med
4. Martin F, Poyen D, Bouderlique E et al
. Depression and burnout in hospital health care professionals. Int J Occup Environ Health
5. Jackson SH. The role of stress in anesthetists' health and well-being. Acta Anaesthesiol Scand
6. Kluger MT, Townend K, Laidlaw T. Job satisfaction, stress and burnout in Australian specialist anaesthetists. Anaesthesia
7. Howard SK, Gaba DM, Smith BE et al
. Simulation study of rested versus sleep-deprived anesthesiologists. Anesthesiology
8. Lockley SW, Cronin JW, Evans EE et al
. Harvard Work Hours, Health and Safety Group. Effect of reducing interns' weekly work hours on sleep and attentional failures. N Engl J Med
9. Halbach MM, Spann CO, Egan G. Effect of sleep deprivation on medical resident and student cognitive function: a prospective study. Am J Obstet Gynecol
10. Deaconson TF, O'Hair DP, Levy MF et al
. Sleep deprivation and resident performance. JAMA
11. Lederer W, Benzer A. Programming errors from patient-controlled analgesia. Can J Anaesth
12. Smith-Coggins R, Rosekind MR, Hurd S, Buccino KR. Relationship of day versus night sleep to physician performance and mood. Ann Emerg Med
13. Katz JD. Issues of concern for the aging anesthesiologist. Anesth Analg
14. Travis KW, Mihevc NT, Orkin FK, Zeitlin GL. Age and anesthetic practice: a regional perspective. J Clin Anesth
15. Deakin J, Aitken M, Robbins T, Sahakian BJ. Risk taking during decision-making in normal volunteers changes with age. J Int Neuropsychol Soc
16. Pincus T, Williams AC, Vogel S, Field A. The development and testing of the depression, anxiety, and positive outlook scale (DAPOS). Pain
17. Miller JM, Harvey EM, Dobson V. Visual acuity screening versus noncycloplegic autorefraction screening for astigmatism in Native American preschool children. J AAPOS
18. Bussing A, Perrar KM. Burnout measurement. Study of a German version of the Maslach Burnout Inventory (MBI-D). Pflege Z
19. Kerr JS, Hindmarch I, Sherwood N. Correlation between doses of oxazepam and their effects on performance of a standardized test battery. Eur J Clin Pharmacol
20. Hindmarch I, Gudgeon AC. The effects of clobazam and lorazepam on aspects of psychomotor performance and car handling ability. Br J Clin Pharmacol
21. Hindmarch I. A pharmacological profile of fluoxetine and other antidepressants on aspects of skilled performance and car handling ability. Br J Psychiat
22. Wilson AM, Weston G. Application of airline pilots' hours to junior doctors. BMJ
23. Wilkening R. The age 60 rule: age discrimination in commercial aviation. Aviat Space Environ Med
24. Harma MI, Hakola T, Akerstedt T, Laitinen JT. Age and adjustment to night work. Occup Environ Med
25. McManus IC, Winder BC, Gordon D. Are UK doctors particularly stressed? Lancet
26. Seeley HF. The practice of anaesthesia
– a stressor for the middle aged
27. Barger LK, Cade BE, Ayas NT et al
. Extended work shifts and the risk of motor vehicle crashes among interns. New Engl J Med