Evaluation of Cognitive and Psychomotor Functional Changes in Anesthesiology Residents after 12 hours of Continuous Work in Operation Theater: An Observational Study.

Background: Prolonged working hours in operation theater may impair cognitive and psychomotor function. Aims: This study was done to evaluate the changes in cognitive and psychomotor changes in the anesthesia residents after 6 and 12 h of continuous work in operation theater. Settings and Design: Sixty anesthesia residents whose working hours were expected to be longer than 12 h were recruited for this prospective, observational study.
Methods: The study consisted of a set of five tests used for assessing the cognitive and psychomotor functions. The tests were conducted for the participants at 0, 6, and 12 h of work and the total scores at the respective time period were noted. The tests were manual dexterity test using purdue peg board, finger tapping test, visual spatial capacity memory test, digit symbol substitution test (DSST), and frontal assessment battery. Statistical Analysis: The observations of the purdue peg board test, finger tapping test, and digit symbol substitution test at 0, 6, and 12 h were tested using the repeated measures analysis of variance and paired t-test. The observations of visual spatial capacity memory test and frontal assessment battery were tested using the Chi-square test.
Results: In the purdue peg board test, there was significant reduction in the mean number of pins assembled by the participants over 12 h of work. There was a significant difference in the number of finger taps by the dominant hand between 0 and 12 h and also between 6 and 12 h. In the visual spatial memory test, there was no significant difference in the performance of the participants with incorrect response at 0 and 12 h of duration. There was a significant decrease in the number of correct response among the participants in the digit symbol substitution test at 0 and 12 h of work. There was no significant difference in the scores obtained in frontal assessment battery test which was used to assess the cognitive function.
Conclusion: There was a significant reduction in the psychomotor functions of the anesthesiology residents after 12 continuous hours of work in the operation theater and there was no significant reduction in cognitive function observed during that period. Copyright:

INTRODUCTION

Anesthesiology is a field which requires rapid decision making with prompt and early action during patient management. Optimal cognitive and psychomotor functions are crucial in key decision making and responsive action during critical perioperative events but these functions may be impaired to varying degrees in residents after prolonged working hours secondary to fatigue.[1234] This may lead to impaired decision-making and impaired reflex motor skills and might affect the quality of patient management inside the operation theater.[5678] The working hours of anaesthesiology residents often gets prolonged exceeding 12 h either due to increased surgical duration of some complex surgeries or due to increased number of surgeries being posted in a day.[910] Fatigue due to increased work hours may impair professional performance, ability to learn, and family life.[11] Studies evaluating the impact of the duration of work on changes in the cognitive and psychomotor functions in anaesthesiology residents are scarce. Hence, this observational study was done to see the changes in cognitive and psychomotor functions among anesthesiology residents after 6 and after 12 h of continuous work in the operation theater.

METHODS

After approval by the institutional research committee, ethics committee and registration in clinical trials registry of India (CTRI/2018/02/012219) participants were enrolled in the study. A total of 60 anesthesiology residents were recruited for the study. Residents include the junior residents doing their postgraduation training in anesthesiology and senior residents who were doing their 3 years of residency after completion of their postgraduation. The inclusion criteria for the study included all the anesthesiology residents who were posted in operation theaters which were anticipated to function for more than 12 h based on the list of cases posted on that particular day. The exclusion criteria included those residents who had night duty on the previous day, any disability or trauma involving either of their upper limbs, history of any central nervous system disease that may impair test performance including head injury, stroke and residents with history of diabetes mellitus, hypertension. The residents who participated in the study previously were also excluded.

An informed written consent was obtained from the residents on the night before the scheduled day of duty. Sixty residents were recruited for the study. Out of those, 5 were excluded since the operation theater concluded before the anticipated 12 h. A set of five tests assessing the cognitive and psychomotor functions were done for the participants at 0, 6, and 12 h of work and the total scores at the respective time period were noted. The tests were not repeated on the same resident. Figure 1 shows the participant selection, recruitment and how the study was performed. The tests which were performed are as follows:

Figure 1

Consort diagram

Manual dexterity test using purdue peg board

Purdue peg board consists of a board with holes in it. The participant was expected to insert pins (pegs) as fast as possible in the board over a 30 s period using dominant and nondominant hands separately. Later, the participant was expected to use both hands simultaneously and do the test over a 30 s period. Subtest involves placement of parts such as washer and collar over the pin. This is called as an assembly. The score of the subtest is equal to the number of parts assembled. The time taken to place the pins in holes over a period of 30 s was measured separately at 0, 6, and 12 h of work. We did not do the sub test.

Finger tapping test

Here the resident was expected to make as many taps as possible using his index finger over a 10 s period. An android application called “Speed Tapping – Tap Fast!” designed by rise up labs was used for this purpose. Three trials of 10 s for each trial were conducted for each hand, and the mean score was taken. The mean score at 0, 6, and 12 h of duty was recorded.

Digit symbol substitution test (DSST)

DSST comprises matching digits with their corresponding symbol within a time limit. The digits along with the corresponding symbols were located in a legend given at the top of the page. Nine such digits will be assigned symbols in the legend. It is analyzed by the number of digits correctly matched with the corresponding symbols within 90 s.

Visual spatial capacity memory test

In this test, the residents were expected to observe a set of colored squares which were displayed in front of them on a computer screen for a period of 5 s. They were expected to remember the particular set. The squares then disappear for 5 s and then reappear with color changes. Residents were expected to notice the change, whether the display was the same or whether one of the squares had changed from one color to another and record their response as YES/NO within 2 s. After a period of 5 s, new pattern of colours appeared and the test was repeated. Five such trials were done. It took about 2 min. The total no of incorrect responses at 0, 6, and 12 h of duty was recorded. Visual spatial capacity memory test is utilized for the assessment of cognitive function.

Frontal assessment battery

It is a battery of six tests that test for specific frontal lobar functions such as abstract thinking, executive functioning (motor sequencing task), attentional processes, inhibitory control, etc., The score ranges from 0 to 18 and a score >12 indicates normal frontal lobar function. Performing the task took about 10 min.

The primary objective was to evaluate the cognitive and psychomotor performance in anesthesiology residents before and after 12 h of continuous work in operation theater. Sample size determination was done based on the study done by Perdana et al.[12] to show the expected clinical difference of psychomotor functional changes between baseline and after 12 h of duty among anesthesiology residents with three absolute units obtained from (53.80 ± 6.3, 56.01 ± 5.23) pooled standard deviation (SD) of 5.75 units, sample size studied in between 54 and 72 will yield power of 80%–90%, respectively. Sample size calculation was based upon the paired t-test formula. Hence, a sample size of 55 was taken. Convenience sampling was done.

Statistical analysis

Statistical data was analyzed by using SPSS version 19 (IBM Corp,Armonk, N.Y,USA). The results were considered significant if P < 0.05. Normality of distribution of data was determined using Kolmogorov − Smirnov tests of normality. All continuous variables were presented in terms of arithmetic mean, SD or median/interquartile. The observations of the purdue peg board test, finger tapping test, and DSST at 0, 6, and 12 h were tested using repeated measures analysis of variance and paired t-test. The observations of visual spatial capacity memory test and frontal assessment battery were tested using the Chi-square test.

RESULTS

The demographic characteristics of the study participants are represented in the Table 1. Sixty residents were enrolled in the study. Among them, 5 participants dropped out since their working hours was <12 h [Figure 1]. The mean (SD) age of the study participants was 27.5 (2.45). Among the participants, about 34 (61.8%) were male and the remaining 21 (38.2%) were female. About 67.3% (n = 37) were junior residents and 32.7% (n = 18) were senior residents. The mean (SD) weight of the study participants was 66.4 (13.4) kg. The mean (SD) height of the study participants was 1.66 (0.09) meters. The average body mass index was 23.7 kg.(m2)−1. Among the participants, about 17 (30.9%) had the previous night duties within 2–3 days. About 32 (58.2%) had their previous night duties in the last 4–5 days. The mean (SD) Pittsburgh Sleep Quality Index score was 4.93 (2.67) and the median interquartile range score was 4 (3–6) [Table 2].The mean (SD) duration of exposure to gaseous agent in the operation theaters was 10.6 h (0.7).

Table 1

Description of the demographic characteristics of the study participants (n=55)

Characteristic	Mean±SD/frequency, n (%)
Age (years)	27.5±2.45
Gender (male/female)	34/21 (61.8/38.2)
Junior resident/senior resident	37/18 (67.3/32.7)
Height (meters)	1.66±0.09
Weight (kg)	66.44±13.4
BMI	23.7±3.2

Age, height, weight and BMI are represented as mean±SD, gender and grade of resident are expressed as a n (%). BMI: Body mass index, SD: Standard deviation

Table 2

Description of the clinical characteristics of the study participants (n=55)

Characteristic	Mean±SD/frequency, n (%)
Timing of previous night duty
2-3 days back	17 (30.9)
4-5 days back	32 (58.2)
6 or more days back	6 (10.9)
Duration of exposure to anaesthetic agent (h)	10.6±0.7
PSQI score	4.93±2.67

The timing of previous night duty is represented as a n (%), The duration of exposure to anesthetic inhalational agent and PSQI score are represented as mean±SD. PSQI: Pittsburgh sleep quality index, SD: Standard deviation

The comparison of the results of Purdue peg board test over different time points is shown in Table 3. The mean number of pins assembled over 30 s time duration at various time points shows that there was a difference in the number of pins assembled by the dominant hand between 0 and 6 h (P = 0.034) and also between 0 and 12 h (P = 0.016) but not between 6 and 12 h (P = 0.222) of work. The mean number of pins assembled by the dominant hand decreased from 15.2 to 14.8 over 12 h of work and the reduction was statistically significant (F = 4.365, P = 0.021).

Table 3

Purdue peg board test over different time points (n=55)

Time point	Dominant hand (number of pins)	Nondominant hand (number of pins)	Both hand (number of pins)
At 0 hour (mean±SD)	15.2±2.0	12.2±1.9	8.9±0.9
After 6 h (mean±SD)	14.9±2.2	12.1±1.8	8.9±0.9
After 12 h (mean±SD)	14.8±2.2	11.9±1.8	8.8±0.9
P (between 0 h and 6 h)^	0.034*	0.071	0.568
P (between 0 h and 12 h)^	0.016*	0.011*	0.049*
P (between 6 h and 12 h)^	0.222	0.140	0.034*
P #	0.021*	0.017*	0.055

*P<0.05, # Repeated measures ANOVA being used, ^ Paired sample t-test being used. SD: Standard deviation

There was a difference in the number of pins assembled by the nondominant hand between 0 and 12 h (P = 0.011) but not between 0 and 6 h (P = 0.071) and between 6 and 12 h (P = 0.140). The mean (SD) number of pins assembled by the nondominant hand also decreased from 12.2 to 11.9 over 12 h of work and the reduction was statistically significant (F = 4.537, P = 0.017).

There was difference in the number of pins assembled by both hands between 0 and 12 h (P = 0.049) and between 6 and 12 h (P = 0.034) but not between 0 and 6 h (P = 0.568) [Figure 2]. The reduction in the mean number of pins assembled by both hands over 12 h of work did not show statistical significance (F = 3.165, P = 0.055).

Figure 2

Purgue board test with both hands at different time points

The mean number of finger taps as measured in the finger tapping test over three different time points is represented in Table 4. There was a significant difference in the number of finger taps by the dominant hand between 0 and 12 h (P = 0.018) and also between 6 and 12 h (P = 0.032) but not between 0 and 6 h (P = 0.364). The trend in the reduction of mean number of finger taps by the dominant hand over 12 h period was statistically significant (F = 4.763, df = 2, P = 0.019).

Table 4

Finger tapping test in 10 s over different time points (n=55)

Time point	Dominant hand (number of taps)	Nondominant hand (number of taps)
At 0 h (mean±SD)	70.5±8.8	62.6±7.1
At 6 h (mean±SD)	70.3±8.7	62.4±6.9
At 12 h (mean±SD)	69.7±8.4	62.2±6.6
P (between 0 h and 6 h)^	0.364	0.230
P (between 0 h and 12 h)^	0.018*	0.122
P (between 6 h and 12 h)^	0.032*	0.334
P #	0.019*	0.171

*P<0.05, # Repeated measures ANOVA being used, ^ Paired sample t-tests being used

There was no significant reduction in the mean number of finger taps by the nondominant hand (F = 1.851, df = 2, P = 0.171).

The results of digit symbol substitution test are being represented in Table 5. The mean (SD) number of correct responses in DSST was 65.4 (10.2) at 0 h and 64.2 (9.4) at 12 h [Figure 3]. The difference in the number of correct responses was significantly different between 0 and 12 h (P = 0.011) and also between 6 h and 12 h (P = 0.047) but not between 0 and 6 h (P = 0.066). The mean (SD) number of correct responses in DSST decreased over time and the reduction was statistically significant (F = –5.443, P = 0.011).

Table 5

Digit symbol substitution test (number of correct matches) at different time points (n=55)

Timing	Number of correct matches (mean±SD)
At 0 h	65.4±10.2
At 6 h	64.8±9.7
At 12 h	64.2±9.4
P (between 0 h and 6 h)^	0.066
P (comparison between 0 h and 12 h)^	0.011*
P (comparison between 6 h and 12 h)^	0.047*
P #	0.011*

*P<0.05, # Repeated measures ANOVA being used, ^ Paired t-test being use

Figure 3

Mean number of correct response in digital symbol substitution test at different time points

The findings of the visual spatial capacity memory test over different time points is represented in Table 6. The number of participants with nil incorrect response decreased from 34 (61.8%) at 0 h to 31 (56.4%) at time-12 h. However the difference in the distribution of incorrect response was not statistically significant (P = 0.223).

Table 6

Comparison of visual spatial capacity memory test over different time points (n=55)

Number of incorrect responses	At 0 h, n (%)	At 6 h, n (%)	At 12 h, n (%)
0	34 (61.8)	30 (54.5)	31 (56.4)
1	13 (23.6)	17 (30.9)	15 (27.3)
2	8 (14.5)	7 (12.7)	7 (12.7)
3	0	1 (1.8)	2 (3.6)

χ2=2.898, df=6, Exact sig=0.8215

The distribution of frontal assessment battery scores at various time points is shown in Table 7 and the difference in distribution was not statistically significant (P = 0.904).

Table 7

Comparison of scores of frontal assessment battery at different time points (n=55)

FAB scores distribution	At 0 h, n (%)	At 6 h, n (%)	At 12 h, n (%)	P
17	12 (21.8)	13 (23.6)	14 (25.5)	0.904
18	43 (78.2)	42 (76.4)	41 (74.5)

χ2=0.201, df=2, P=0.904. FAB: Frontal assessment battery

DISCUSSION

Our study was designed to assess the change in cognitive and psychomotor function of the anaesthesia residents after 12 h of continuous work in operation theatre. The findings of our study showed a significant decrease in the psychomotor function of the residents after 12 h of continuous work in the operation theatre as elicited by purdue pegboard, finger tapping test and digit symbol substitution test. There was no significant difference in the cognitive function as assessed by visual spatial capacity memory test and frontal assessment battery test.

Purdue pegboard test is used to measure unimanual and bimanual finger and hand dexterity. It is also used in neuropsychological assessment to assist in localizing cerebral lesions and deficits. A good unimanual and bimanual finger and hand dexterity is expected from an anaesthesiologist especially when he or she is expected to act quickly and do multiple works at a time and it was assessed using Purdue peg board test.[13] There was significant reduction in the mean number of pins assembled by the dominant hand and nondominant hand over a period of 12 h. However the reduction in the mean number of pins assembled by both hands failed to show a statistical significance. The mean number of pins assembled by the dominant and nondominant hand between 6 and 12 h failed to show a statistical significance though they showed a statistical significance between 0 and 6 h, and 0 and 12 h. This might denote that working for 6 h showed a similar deterioration in psychomotor function as that of working for 12 h. The results of Purdue peg board test shows that there is a significant reduction in the psychomotor function of the residents in terms of manual dexterity after 12 h of work.

Finger tapping test is primarily used to evaluate fine motor function. The psychomotor function assessed using finger tapping test showed that the mean number of finger taps by the dominant hand significantly reduced from 70.5 to 69.7 between 6 and 12 h and there was no change in the performance between 0 and 6 h. This shows that the decline in psychomotor function at 12 h was significantly more when compared to the decline at 6 h. The results signify that there is a significant reduction in the psychomotor function after 12 h of work.

Visual spatial capacity memory test is used to assess memory of recall. The number of participants with nil incorrect response decreased from 34 (61.8%) 31 over a 12 h period. However the difference in the distribution of incorrect responses was not statistically significant (P = 0.223).

DSST is one of the most commonly employed tests in neuropsychology. It has a significant advantage over many of the cognitive and psychomotor tests because of it's brevity and reliability.[14] A good motor speed, visuo-perceptual function and attention is required to perform well in this test. The test is also influenced by associative learning and mood. Moreover if the participant consciously puts an effort to engage in learning strategy to improve the performance, then his or her executive functions of planning and strategy making will also come into play. To sum up, DSST has a high sensitivity to detect impairment in processing speed, executive functioning and working memory, but low specificity to determine exactly which domain among these is particularly impaired. In our study, the mean number of correct responses in DSST decreased over time and the reduction was statistically significant (P = 0.011). Moreover the mean number of correct responses showed a statistical significance between 6 and 12 h (P = 0.047) and failed to show a statistical significance between 0 and 6 h (P = 0.066). This infers that there is a statistical decline in the cognitive and psychomotor function with respect to Digit Symbol Substitution Test.

There was significant reduction in performance speed noted in the tests that depend more on manual dexterity and motor speed (purdue peg board test, finger tapping test, digit symbol substitution test) and this indicates a reduction in psychomotor performance. However, the frontal assessment battery test, which evaluates predominantly the cognitive performance with minimal emphasis on motor speed did not show any reduction in scores across the time points. This is possibly because of the fact that the frontal assessment battery predominantly relies on frontal cognitive performance rather than psychomotor speed and may not be able to detect slight reduction in performance among the highly educated group of subjects.[15]

In the previous study conducted by Perdana et al.,[12] among the different cognitive stimulation tests performed, sequential image frequency test alone showed a statistical significance proving that there was a significant decrease in the cognitive function in terms of attention, visual memory, naming and executive function. Whereas the other 5 tests in the cognitive stimulation tests failed to show a statistical significance. The grooved pegboard test which was used to assess the psychomotor function showed a statistical significance proving that there was a significant decrease in the psychomotor function as well among residents. However in their study, the tests were conducted only at two time points (0 and 12 h). Whereas in our study the tests were conducted at 3 different time points (0, 6 and 12 h) and were compared. Hence we were able to compare and infer the changes in cognitive and psychomotor function between 6 and 12 h as well. This gives us additional information regarding the difference in cognitive and psychomotor function between routine work hours and prolonged work hours.

Karanovic et al.[16] studied the effect of single 24 h work shift in the cognitive and psychomotor performance of the attending anaesthesiologists. The average duration of time spent in operation theatre during the shift was 15 h. In contrast to our study, they utilized four computer generated psychological tests (complex reactionmeter drenovac). The results of their study also showed a significant alteration in cognitive and psychomotor performance of the anaesthesiologist after a 24 h working shift.

In contrast to our study with all the study participants belonging to an younger age group, Lederer et al. studied the effect of psychomotor performance after 24 in house on call duty in young and senior anaesthetists.[17] They concluded that although tiredness and decline in concentration abilities subjectively was high in senior anaesthesiologists after duty, there was no significant difference in the performance assessed by psychometric testing between the two age groups. Age and individual sleep characteristics also have been found to impair the cognitive performance.[18]

Taking into consideration that the primary cognitive function test which was used in our study was not sensitive enough to find out the changes in cognitive function in our highly educated study population, we conclude that there was a significant reduction in the psychomotor functions of the anaesthesiology residents when they worked for 12 continuous hours in the operation theatre.

Our study has some limitations. Even though a period of 1 h outside the operation theatre was accepted in the 12 h of continuous work, the exact duration for which the resident availed that period of break was not documented. We did not collect information whether the tests were performed before or after food intake by the residents especially with the tests done at 6 and 12 h of work. It could have resulted in some variation of test results. Residents who were posted in both elective and emergency services were included in the study and they were not categorized into different groups. This may have been a confounding factor. Information regarding the complexity of the cases to be managed on that particular day on a subjective basis hasn’t been gathered. Though all cases require the maximum vigilance of the anaesthesiologist, managing some complicated cases might had been comparatively tiresome when compared to managing rest of the common cases.

CONCLUSION

There was a significant reduction in the psychomotor functions in the anaesthesiology residents after 12 continuous hours of work in the operation theatre and there was no significant reduction in cognitive function observed during that period.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.