Cognitive dysfunction in anaesthesiologists can be detrimental not only to their personal lives, but also for the patients they care for. Many factors related to the work environment, such as noise, temperature and exposure to anaesthetic vapours, as well as human factors, e.g. sleep deprivation, fatigue, stress and workload, may result in temporary or long-term detrimental effects on the cognitive functioning of anaesthesiologists .
The hypothesis was that working in the operating room caused chronic cognitive deficits in anaesthesiologists. To test this hypothesis, the cognitive function of anaesthesiologists was compared with other physicians not working in the operating room by the use of a self-report, neuropsychological tests and an event-related cognitive evoked potential, P300. Among the cognitive functions, specifically attention and memory-related cognitive functions were chosen because of their vital role for intraoperative vigilance (monitoring, record keeping, etc.).
Twenty-six anaesthesiologists from the Hacettepe University Department of Anaesthesiology who had been actively working in passively scavenged operating rooms for more than 1 yr volunteered to participate in the study after institutional Ethics Committee approval. The following exclusion criteria were used: (a) on-call the night before, (b) intensive care work in the previous 6 months, (c) use of drugs acting on the central nervous system, (d) a diagnosis of endocrine and/or psychiatric disease, (e) pregnancy, (f) operation or any major health problem in the previous 6 months and (g) vacation in the previous 6 months. Twenty-two anaesthesiologists were included. A control group of 22 physicians, matched for gender and academic status, from other departments of the same hospital were randomly selected to participate in the study. The control group consisted of 10 paediatricians, seven internal medicine physicians, three pathologists and two radiologists.
The tests chosen covered many aspects of the attention- and memory-related cognitive functions. (a) A self-report questionnaire, the Cognitive Failures Questionnaire, that measures cognitive lapses in perception, memory or a misdirected action that may occur in everyday life . Many different groups (healthcare personnel, car factory workers, managers working in a factory, etc.) were studied using this questionnaire . (b) Psychometric tests measuring attention, concentration, immediate as well long-term memory via the word list (Rey Auditory Verbal Learning test) and digit span tests (Visual Aural Digit Span test), the Benton Visual Retention test, verbal fluency and word association tests. These psychometric tests have been widely used in monitoring hazardous workplace exposures . (c) A highly objective standardized neurophysiological test, event-related evoked potential, P300. P300 represents the transfer of information to consciousness and measures the cognitive operations related to attention allocation and memory updating. It also has been widely used in studies evaluating central nervous system dysfunction related to occupational and environmental hazardous factors .
Both anaesthesia and control groups each consisted of 16 female and six male volunteers. There were 15 residents and seven consultants in each of the two groups. The ages of anaesthesiologists (32.5 ± 5.6 yr) and the control group (32 ± 5.9 yr) physicians were similar (P > 0.05). The anaesthesia group was exposed to N2O and halothane for 12-204 (median 54) months, isoflurane for 12-60 (54) months and enflurane for 0-24 (2) months. Statistical analyses were made using the χ2-test, t-test, Mann-Whitney U-test, Pearson or Spearman analyses, and linear regression analysis where appropriate.
There was no clinically significant difference between the neuropsychological test results of the two groups (Table 1). There were no significant differences between the P300 latencies of anaesthesiologists (322 ± 27 ms) and control group physicians (324 ± 21 ms) (P > 0.05). The mean P300 amplitude of the anaesthesia group (8.12 ± 4.75 μV) was also similar to the control group (7.72 ± 4.53 μV). Both anaesthesiologists and control group physicians had subjective symptoms of cognitive failures as assessed by the cognitive failure questionnaires (37 ± 13 and 34 ± 10, respectively, P > 0.05).
No correlation was found between the Cognitive Failures Questionnaire scores and any of the neuropsychological tests or between the Cognitive Failures Questionnaire scores and the P300 latency. P300 latency was correlated with age (P = 0.003, r = 0.444) and nitrous oxide (P = 0.036, r = 0.325), but age was the only independent variable affecting the latency of P300 (P = 0.003) in regression analysis.
The results suggest that anaesthesiologists working in operating rooms do not have chronic attention- and memory-related cognitive deficits compared with other physicians. A previous study pointed out that non-anaesthetic factors such as stress, arousal, workload and work autonomy might be even more important than exposure-related factors to influence the cognitive function of anaesthesiologists . Therefore, in the present study, interest was in the chronic impairment due to overall working conditions rather than in the acute effects of anaesthetics per se. Similar to the present results, but lacking neurophysiological testing, Lucchini and colleagues' multicentre trial found that operating theatre personnel and non-exposed hospital workers were comparable in their basic intellectual abilities and subjective stress levels, and that work in the operating room or exposure to anaesthetic gases was not associated with cognitive dysfunction .
In the present study, anaesthesiologists and control group physicians self-reported cognitive failures. Although the cause of these cognitive failure symptoms in both groups is unknown, this may suggest a general problem within medicine, potentially influencing patient care. These cognitive failures are typified in aviation by the pilot who sets his course by the wrong end of the compass needle, or who shuts down the surviving engine when one fails . Self-reported cognitive failures were strongly associated with stress and anxiety, and correlated with depression scores [2,7]. The high Cognitive Failures Questionnaire scores indicate the need for further testing and investigation of factors such as depression, anxiety and stress in physicians.
Note that the present study was on a limited number of volunteers and therefore was not adequately powered to detect a small difference between the groups. Nevertheless, this is the first occupational study to the authors' knowledge to compare the event-related evoked potential P300 of anaesthesiologists with a matched group of other physicians. In conclusion, no detrimental chronic effect could be shown on attention- and memory-related cognitive function of anaesthesiologists compared with a matched control group physicians.
S. B. Akinci
Department of Anesthesiology and Reanimation; Hacettepe University; Ankara, Turkey
The work was presented at the 12th World Congress of Anaesthesiologists, 4-9 June 2000, Montreal, Quebec, Canada.
1. Weinger MB, Englund CE. Ergonomic and human factors affecting anesthetic vigilance and monitoring performance in the operating room environment. Anesthesiology
2. Broadbent DE, Cooper PF, FitzGerald P, Parkes KR. The Cognitive Failures Questionnaire (CFQ) and its correlates. Br J Clin Psychol
3. Rasmussen K, Jeppesen HJ, Sabroe S. Psychometric tests for assessment of brain function after solvent exposure. Am J Ind Med
4. Araki S, Murata K. Determination of evoked potentials in occupational and environmental medicine: a review. Environ Res
5. Stollery BT, Broadbent DE, Lee WR, Keen RI, Healy TEJ, Beatty P. Mood and cognitive functions in anaesthesiologists working in actively scavenged operating theatres. Br J Anaesth
6. Lucchini R, Belotti L, Casitto MG, et al.
Neurobehavioral functions in operating theatre personnel: a multicenter study. Med Lav
7. Mahoney AM, Dalby JT, King MC. Cognitive failures and stress. Psychol Rep