Surg Endosc DOI 10.1007/s00464-014-3899-6
and Other Interventional Techniques
Psychophysical workload in the operating room: primary surgeon versus assistant Annika Rieger • Sebastian Fenger • Sebastian Neubert Matthias Weippert • Steffi Kreuzfeld • Regina Stoll
•
Received: 6 February 2014 / Accepted: 10 September 2014 Ó Springer Science+Business Media New York 2014
Abstract Background Working in the operating room is characterized by high demands and overall workload of the surgical team. Surgeons often report that they feel more stressed when operating as a primary surgeon than in the function as an assistant which has been confirmed in recent studies. In this study, intra-individual workload was assessed in both intraoperative functions using a multidimensional approach that combined objective and subjective measures in a realistic work setting. Methods Surgeons’ intraoperative psychophysiologic workload was assessed through a mobile health system. 25 surgeons agreed to take part in the 24-hour monitoring by giving their written informed consent. The mobile health system contained a sensor electronic module integrated in a
Annika Rieger and Sebastian Fenger are co-first authors. A. Rieger (&) M. Weippert S. Kreuzfeld R. Stoll Institute for Preventive Medicine, Rostock University Medical Center, Rostock, Germany e-mail: [email protected] A. Rieger M. Weippert R. Stoll Center for Life Science Automation, University of Rostock, Rostock, Germany S. Fenger MedAdvisors GmbH, Hamburg, Germany S. Fenger Department of Cardiac and Thoracic Vascular Surgery, University Medical Center Schleswig–Holstein, Lu¨beck, Germany S. Neubert Institute of Automation, University of Rostock, Rostock, Germany
chest belt and measuring physiological parameters such as heart rate (HR), breathing rate (BR), and skin temperature. Subjective workload was assessed pre- and postoperatively using an electronic version of the NASA-TLX on a smartphone. The smartphone served as a communication unit and transferred objective and subjective measures to a communication server where data were stored and analyzed. Results Working as a primary surgeon did not result in higher workload. Neither NASA-TLX ratings nor physiological workload indicators were related to intraoperative function. In contrast, length of surgeries had a significant impact on intraoperative physical demands (p \ 0.05; g2 = 0.283), temporal demands (p \ 0.05; g2 = 0.260), effort (p \ 0.05; g2 = 0.287), and NASA-TLX sum score (p \ 0.01; g2 = 0.287). Conclusions Intra-individual workload differences do not relate to intraoperative role of surgeons when length of surgery is considered as covariate. An intelligent operating management that considers the length of surgeries by implementing short breaks could contribute to the optimization of intraoperative workload and the preservation of surgeons’ health, respectively. The value of mobile health systems for continuous psychophysiologic workload assessment was shown.
Keywords Intraoperative workload Primary surgeon Assistant Heart rate Breathing frequency NASA Task Load Index Operation duration In recent years, psychophysical workload of healthcare professionals came more and more into focus of public and scientific interest [1]. High workload as a multifaceted construct which is determined by the interaction of task demands, task circumstances, skills, behavior, and perception of the individual [2, 3], has been shown to affect performance and health of physicians [4, 5]. Especially in
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surgical disciplines, complex processes of change such as the introduction of new technologies, new surgical methods, or permanent changing surgical teams lead to high workload [6]. Further stressors might be e.g. intraoperative complications, inconsistencies in the surgical team, interruptions in work flow, hours of work, and personal characteristics such as fatigue, illness, or physical discomfort [4, 7–9]. The human response to the above mentioned stressors can be either of emotional, physical or mental nature or expressed by the individual behavior [4]. In the literature, occupational workload is known as a risk factor for the development of hypertension and coronary heart disease [10–14]. Therefore, the assessment of psychophysical workload in demanding work settings such as the surgical discipline is of particular interest. Likewise, evaluating workload is an important component of system design and analysis [3]. Given drawbacks of subjective assessment methods, by now, many researchers have turned toward measuring physical responses of surgeons for assessing their mental workload. While subjective workload measures attempt to quantify the effort exerted during task performance [3, 15], physiological responses to work provide more detailed and diagnostic information. For this reason, measurements should be based on various workload indices [2]. Associations between physiologic responses controlled by the sympathetic nervous system and mental stress experienced by the surgeon [7] support the idea of a complex methodology that combines both physical and psychological workload indicators. To ensure work flow in real-life investigations, short questionnaires that can be answered promptly should be adopted. Such assessment tools have proven their feasibility in terms of overall workload identification [16]. Surgeons have to adjust themselves to the daily workload and adapt to rapid changes. While single demands are to meet without difficulty, the combination of different loads can lead to a very high stress experience and—as a result—to human error [4, 17]. Special attention is given to the operating room (OR) as a place where great demands are made on the medical staff and where conflicts have to be solved quickly and successfully [6, 18, 19]. Since one-third of the daily working time of surgeons is dedicated to surgical procedures [1], this activity is of crucial interest when analyzing individual workload behavior. Procedural and decision errors have a major impact on the work and may be irreversible at worst. The intraoperative functioning of the surgeon is of major importance because of the great responsibility for the safety and the success of the treatment. First insights into the physiological workload responses of surgeons in the OR were given by Kuhn et al. who assessed workload by analyzing heart rate and sympatho-vagal balance taking into account the experience of the surgeon and his role in
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the OR [20]. The authors concluded e.g. that during surgery both primary operators as well as assistants responded with significantly increased heart rate (HR) compared to baseline HR. Furthermore, some researchers spotted that working as main surgeon can be considered as a potential stressor [11, 21–23]. However, so far it is not known whether the amount of intra-individual workload differs when operating as primary surgeon or assistant. This study determined whether there were any differences in psychophysiologic workload between the two roles, primary operator and assistant using an intra-individual study design with two measuring times. We hypothesized that in the role as primary operator, greater objective and subjective workload becomes evident than in the role as assistant.
Methods The prospective cross-sectional study was based on a psychophysiological 24-h monitoring with a total sample of 25 physicians from surgical disciplines. 24 men and one woman from two hospitals of Northern Germany took part voluntarily without financial reimbursement after having given their written informed consent. Eligibility criteria comprised sufficient language skills to ensure the comprehension of Ecological Momentary Assessments (EMA), absence of acute or chronic illnesses, and adverse drug status. Furthermore, a regular work day without shifts was required the day before monitoring as well as the ultimate day of investigation, respectively. Participants were given a written assurance of highly confidential handling of private data according to the guidelines for data privacy. The study was approved by the Ethics Committee of the Rostock University Medical Center (A2012-0075). Real-life monitoring approach Prior to monitoring, all subjects were informed about the study design and introduced in the handling of the mobile health system which has been developed in order to assess individual workload response wirelessly, continuously, and in real-time. All investigations were conducted in the real clinical setting and based on a multiparametric monitoring. The health monitoring (Fig. 1) comprised the recording of various physiological measures through a wireless sensor electronic module (FA. Hidalgo, Cambridge), and the documentation of work specifications and individual workload via smartphone. HR and breathing frequency (BF) were recorded continuously during the entire investigation. Three dry electrodes located in a chest belt enabled three channel ECG recordings. BF was obtained via an expansion sensor contained within the monitoring
Surg Endosc Fig. 1 Study design
belt. For online transmission and analysis, running average over 30 s period with a time resolution of four values per minute was calculated for both measures. Accuracy of data was screened using quality measures and information on signal confidence by the sensor. Additionally, the sensor provided information on body movement via a three-axis acceleration sensor and skin temperature by a thermistor located in the sensor module. All measures were sent to a HTC smartphone via Bluetooth. The smartphone was equipped with a mobile health application developed by the medical institution for documentation of daily activities and processing of EMA for subjective workload assessment [24, 25] (Fig. 2). Furthermore, it worked as a middleware, transferring all data to a communication server where data were stored, visualized, and post-processed.
the sum score as a global workload index because results were comparable to the weighted scales in terms of sensitivity [27, 28]. Due to the time constraints in the clinical setting and in order to increase user acceptance, in this study, the six dimensions were considered without former weighting process. The preoperative workload was assessed for reference purposes and acted as a basic value. It had to be evaluated for a determined period of 5 min right before start of surgery. Postoperatively, i.e., right after completion of surgical procedure, the intraoperative workload was assessed. Besides, subjects were asked to answer surgeryrelated questions regarding e.g. the degree of difficulty, the complication rate, the intraoperative role, or the wearing of lead aprons.
Ecological momentary assessments
Statistical analysis
The National Aeronautics and Space Administration Task Load Index (NASA-TLX) [26], which was validated in numerous studies [27], was implemented as an electronic version in the smartphone software and answered immediately before and after surgical procedures. It has been demonstrated that multidimensional assessment of perceived workload with the NASA-TLX rating scale is essential in order to capture the complexity of task effects on operators [28]. The NASA-TLX is a tool that provides an overall workload score based on the six subscales mental demand, physical demand, temporal demand, performance, effort, and frustration. While the original version provides for weighting of each dimension, in recent years, many researchers used the raw values of the subscales or
To determine intra-individual differences in psychophysical workload, only those ten surgeons who conducted both a surgery in the role of the primary surgeon and an operative procedure as an assistant were included in the analyzes. Three chiefs of medicine, three attendings, two fellows, and two residents formed the final sample of the study. The order of intraoperative roles as well as the time of surgery were predetermined by the plan of operation, and therefore in a random order which could not be modified. Analyzes of physical strain were based upon the two measures HR and BF. Furthermore, body movement was considered in order to evaluate HR and BF response. Skin temperature has not been respected for further analyzes because this parameter is subject to many confounders such
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Surg Endosc Fig. 2 Screenshots of software interfaces: Occupational tasks and physiological measures (A), NASA-TLX (B: Subscales 1–3, C: Subscales 4–6), category of surgery (D), degree of difficulty (E), and additional intraoperative information (F)
as ambient temperature, application of leads, or transpiration, and consequently it has to be considered with caution when interpreting workload. The data were analyzed with IBM SPSS Statistics 22.0 for Windows. Multivariate analyses of variance (Manova) were performed to evaluate the effects of intraoperative function on subjective and objective workload responses. Since fatigue raises workload [29] and employees are known to become more stressed over time [28], length of operating procedures was entered as covariate. All statistical tests were two-tailed with the alpha level set at 0.05.
Results The ten surgeons who acted in both functions on the day of monitoring were all male, were recruited at the age of 40.6 ± 9.1 years, and have been working for 10.3 ± 8.1 years in their job. Pre- and intraoperative subjective workload As can be seen from the absolute values in Table 1, in the role as primary surgeon, physicians appear to feel more stressed both before and after surgical procedures. In all
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workload dimensions, operating with higher responsibility led to higher workload scores. While the overall workload remained on an almost identical level when operating as primary operator (increase from pre- to postoperative EMA: 0.56 %), in their role as assistant surgeons’ total workload score decreased by 24.6 % from pre- to postoperative evaluation. However, when considering length of surgeries as possible workload determining factor in the multivariate analysis, the results indicate that none of the NASA-TLX workload dimensions related to the intraoperative role but to duration (Table 2). Thus, the hypothesis of a higher workload when operating with higher responsibility cannot be confirmed. There is only a tendency for preoperative effort (p = 0.096; g2 = 0.155) and NASA-TLX sum score (p = 0.092; g2 = 0.158) to be higher when operating in the role with higher responsibility. In contrast to intraoperative job role, length of surgeries had a significant impact on intraoperative physical demands (p \ 0.05; g2 = 0.283), temporal demands (p \ 0.05; g2 = 0.260), effort (p \ 0.05; g2 = 0.287), and NASA-TLX sum score (p \ 0.01; g2 = 0.287). Furthermore, preoperative physical demand (p \ 0.095; g2 = 0.155) and intraoperative performance (p = 0.096; g2 = 0.154) tended to increase with longer operation duration (Table 1).
Surg Endosc Table 1 Absolute values of pre- and intraoperative subjective workload in both functions (n = 10) Time of assessment
NASA-TLX subscale
Preoperatively
Mental demand
Postoperatively
Primary surgeon M ± SD 55.4 ± 22.4
Assistant M ± SD 35.6 ± 18.3
Physical demand
49.5 ± 24.4
35.5 ± 17.4
Temporal demand
59.4 ± 23.7
42.2 ± 24.7
Performance
48.8 ± 26.6
32.6 ± 27.3
Effort
57.1 ± 18.2
37.6 ± 15.9
Frustration P NASA-TLX
34.1 ± 21.4
14.5 ± 14.1
304.3 ± 82.0
198.0 ± 80.3
Mental demand
65.9 ± 25.3
30.9 ± 23.0
Physical demand
50.4 ± 23.1
30.2 ± 19.7
Temporal demand
64.4 ± 21.6
35.1 ± 20.5
Performance
38.9 ± 32.3
17.7 ± 27.3
Effort
62.2 ± 27.4
27.0 ± 15.0
Frustration P NASA-TLX
24.2 ± 22.3
8.4 ± 9.1
306.0 ± 110.6
149.3 ± 75.7
Descriptive statistics: M mean, SD standard deviation. All subscales of NASATLX were rated from 0 to 100
Intraoperative physical workload A differentiated view on the physiological parameters revealed no differences in HR (p = 0.668; g2 = 0.011) and BR behavior (p = 0.967; g2 = 0.000) for both surgical roles. Length of surgeries tended to have an impact on intraoperative HR (p = 0.72; g2 = 0.178) but not on BR (p = 0.147; g2 = 0.120). Figure 3 and 4 show the level of intraoperative physical workload in both functions.
Discussion In the presented investigation, we used the cross-sectional data of a particularly burdened work group to examine the effects of the intraoperative function on psychophysical workload using a mobile health system. The OR has a special meaning since it represents the central element of each hospital. Often, the lives of patients depend on the services provided in the OR. The large responsibility of the surgeon for the safety and success of patient care is attended by a high workload level of the surgeon. Excessive workloads lead to mental and physical exhaustion, fatigue, and sleep deprivation which may increase the likeliness of medical errors [30–32]. Against the background of an impairment of patient care by factors such as time pressure or overload [33], and the deterioration of health status and well-being due to increasing work densification [10, 34], the study of surgeons intra-individual workload is of particular importance for scientific and
occupational health reasons, respectively. By looking at the individual workload response, researchers get an insight into work exigencies and can develop new health care approaches for employees. To date, several methods for measuring the workload of surgeons in the OR have been applied in order to derive strategies for dealing with high intraoperative physical and mental workload [7]. While some researchers have focused on subjective strain assessment [35], other scientists analyzed cardiac responses [11, 36, 37], or chose a combination of subjective and objective methods [38–40] to identify individual workload responses during different types of surgery or in differently equipped ORs. Many of the previous studies have been limited to simulations in which a virtual environment for special surgical situations has been created due to the difficulty of applying real-time studies in such demanding work settings. Studies that allow for a continuous measurement of physical responses and a mobile recording of subjective workload under everyday working conditions are rare [30]. The advantage of telemedical workload assessment lies in the autonomy of the participants. After oral and written instruction, the presence of the investigator is no longer required. The system collects, processes, and transmits all data wirelessly and in real-time [24] so that the compliance of the subject is the major determining factor in terms of data completeness and data quality [16, 41]. As our results clearly indicate, both the subjective as well as the objective measures do not support the hypothesis of psychophysical workload differences depending on the intraoperative role. In contrast, the multivariate analysis revealed that higher intraoperative workload can be attributed particularly to operation duration. These results confirm earlier findings of changes in workload over task duration indexed by the NASATLX or the Dundee Stress State Questionnaire [28, 42, 43]. In our study, physical demands, temporal demands, and effort emerged as the principal contributors to intraoperative workload. Other researchers found frustration or mental demand to be the leading influencing factors in vigilance tasks [28]. Effects of time on task have mostly been studied in laboratory experiments, and therefore do not adequately reflect realworld effects and often do not reach realistic working time. Thus, the present study makes a contribution to the understanding of workload in different job roles as well as workload changes over time in a naturalistic setting. Since surgery length and not intraoperative function plays a significant role during surgical procedures in our study, the concept of breaks as the ‘‘oldest method to counteract fatigue’’ and to work successfully [44] has to be taken into account. Engelmann and his associates recently summarized that short breaks within surgery decreased the workload of physicians and improved the concentration significantly. The reduced overall workload was explained
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Surg Endosc Table 2 Effects of intraoperative job role and surgery length on perceived workload. Results based on multivariate analyses (n = 10)
Workload Indicator Intraoperative Role
Preoperatively
Intraoperatively
Length of surgery
Preoperatively
Intraoperatively
Fig. 3 Intraoperative heart rate in the role as primary surgeon and assistant
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df
F
p
Partial g2
Mental demand
1
2.643
0.122
0.135
Physical demand
1
0.000
0.984
0.000
Temporal demand
1
0.099
0.757
0.006
Performance
1
0.260
0.617
0.015
Effort
1
3.107
0.096
0.155
Frustration P NASA-TLX
1
3.180
0.092
0.158
1
2.182
0.158
0.114
Mental demand
1
1.936
0.182
0.102
Physical demand
1
0.005
0.947
0.000
Temporal demand
1
0.971
0.338
0.054
Performance
1
0.006
0.942
0.000
Effort
1
1.700
0.210
0.091
Frustration P NASA-TLX
1
0.274
0.607
0.016
1
1.375
0.257
0.075
Mental demand Physical demand
1 1
0.008 3.128
0.930 0.095
0.000 0.155
Temporal demand
1
1.792
0.198
0.095
Performance
1
0.509
0.485
0.029
Effort
1
0.017
0.899
0.001
Frustration P NASA-TLX
1
0.003
0.960
0.000
1
1.136
0.301
0.063
Mental demand
1
2.939
0.105
0.147
Physical demand
1
6.716
0.019
0.283
Temporal demand
1
5.969
0.026
0.260
Performance
1
3.098
0.096
0.154
Effort
1
6.856
0.018
0.287
Frustration P NASA-TLX
1
2.676
0.120
0.136
1
12.211
0.003
0.418
Fig. 4 Intraoperative breathing frequency in the role as primary surgeon and assistant
Surg Endosc
as a consequence of reduced fatigue. Moreover, performance could be sustained without a prolongation of operation time which was very surprising. Taking into consideration the important findings of Engelmann et al. and our results which evidenced that the operation duration is a major influencing factor of surgeon’s workload during surgeries, the public attention should be insistently directed to the suggestion of regular breaks during surgery [45]. In this context, the modification of the surgical management would be a milestone. So far, the surgical management was implemented in German hospitals to increase the efficiency of surgeries for economic reasons. Currently, the German Association for Surgical Management (VOPM) recommends the following key data for a benchmarking: morning start, incision-to-suture time, changing time, and degree of utilization of OR. Until today, individual needs such as psychophysical workload have not been considered in optimization processes. Possibly, a regular break scheme could reduce individual workload responses, optimize employees’ satisfaction, avoid chronic stress, and after all, increase the performance of the surgical team in the long term. Even if in this study only short-term effects of intraoperative workload have been measured, and thus, healthrelated consequences cannot be implied automatically, we assume that chronic high workload conditions in the OR will have a negative impact on health and well-being. There have been limitations of this study that have to be mentioned. Firstly, time-precise answering of EMA depended on the compliance of surgeons. Since EMA were initiated by selection of the appropriate activity in the activity protocol by the surgeon themselves, retardation of data entries could not be excluded. Due to the self-completion of the activity protocol, length of procedures might have also varied a little. Even if ambulatory assessment has many advantages, the reliability of data collection is limited because field studies are only partially controllable [46–49]. Moreover, it should be kept in mind that answers to survey questions can be affected by working memory and the ability in judging task difficulty [7, 40]. The second limitation was the low capacity of smartphone batteries due to continuous data transfer. Subjects were asked to apply additional chargers in case of empty batteries. This could have reduced the wearing comfort of the mobile health system, even if subjects did not mention this in the oral retrospective survey [16]. As with any indirect measure of BF, in the case of measuring breathing via expansion, body motion, activity, or speaking can cause measurement artifacts that can reduce the accuracy of recorded data. After this study has been completed in 2011, a new version of NASA-TLX, the surgery-specific workload index SURG-TLX has been developed and validated. In
future studies, this assessment tool should be used since it has proven to be sensitive to different sources of stress [50].
Conclusion Multidimensional mobile health systems can be a useful tool for assessing the psychophysical workload even in demanding occupations. The present study is supposed to be a contribution to an objectification of psychophysical workload in surgical hospital doctors. The results disprove that working in the role as primary surgeon is associated with higher perceived workload and higher objectively measured cardiopulmonary responses. However, analyzes have shown that operation duration has a major impact on the perceived workload. In order to avoid chronic overload and chronic health threat, the consideration of intraoperative breaks in the surgical management is suggested. Acknowledgments The authors are very grateful to the reviewers for their valuable comments and suggestions. This study was realized as part of the project eHealth MV, funded by the State of Mecklenburg-Western Pomerania in Germany as well as by the Federal Ministry of Education and Research (BMBF) in the program ‘‘Center for Innovation Competence (ZIK)’’. Disclosures Drs. Rieger, Fenger, Neubert, Weippert, Kreuzfeld, and Prof. Stoll have no conflicts of interest or financial ties to disclose.
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and Other Interventional Techniques
Psychophysical workload in the operating room: primary surgeon versus assistant Annika Rieger • Sebastian Fenger • Sebastian Neubert Matthias Weippert • Steffi Kreuzfeld • Regina Stoll
•
Received: 6 February 2014 / Accepted: 10 September 2014 Ó Springer Science+Business Media New York 2014
Abstract Background Working in the operating room is characterized by high demands and overall workload of the surgical team. Surgeons often report that they feel more stressed when operating as a primary surgeon than in the function as an assistant which has been confirmed in recent studies. In this study, intra-individual workload was assessed in both intraoperative functions using a multidimensional approach that combined objective and subjective measures in a realistic work setting. Methods Surgeons’ intraoperative psychophysiologic workload was assessed through a mobile health system. 25 surgeons agreed to take part in the 24-hour monitoring by giving their written informed consent. The mobile health system contained a sensor electronic module integrated in a
Annika Rieger and Sebastian Fenger are co-first authors. A. Rieger (&) M. Weippert S. Kreuzfeld R. Stoll Institute for Preventive Medicine, Rostock University Medical Center, Rostock, Germany e-mail: [email protected] A. Rieger M. Weippert R. Stoll Center for Life Science Automation, University of Rostock, Rostock, Germany S. Fenger MedAdvisors GmbH, Hamburg, Germany S. Fenger Department of Cardiac and Thoracic Vascular Surgery, University Medical Center Schleswig–Holstein, Lu¨beck, Germany S. Neubert Institute of Automation, University of Rostock, Rostock, Germany
chest belt and measuring physiological parameters such as heart rate (HR), breathing rate (BR), and skin temperature. Subjective workload was assessed pre- and postoperatively using an electronic version of the NASA-TLX on a smartphone. The smartphone served as a communication unit and transferred objective and subjective measures to a communication server where data were stored and analyzed. Results Working as a primary surgeon did not result in higher workload. Neither NASA-TLX ratings nor physiological workload indicators were related to intraoperative function. In contrast, length of surgeries had a significant impact on intraoperative physical demands (p \ 0.05; g2 = 0.283), temporal demands (p \ 0.05; g2 = 0.260), effort (p \ 0.05; g2 = 0.287), and NASA-TLX sum score (p \ 0.01; g2 = 0.287). Conclusions Intra-individual workload differences do not relate to intraoperative role of surgeons when length of surgery is considered as covariate. An intelligent operating management that considers the length of surgeries by implementing short breaks could contribute to the optimization of intraoperative workload and the preservation of surgeons’ health, respectively. The value of mobile health systems for continuous psychophysiologic workload assessment was shown.
Keywords Intraoperative workload Primary surgeon Assistant Heart rate Breathing frequency NASA Task Load Index Operation duration In recent years, psychophysical workload of healthcare professionals came more and more into focus of public and scientific interest [1]. High workload as a multifaceted construct which is determined by the interaction of task demands, task circumstances, skills, behavior, and perception of the individual [2, 3], has been shown to affect performance and health of physicians [4, 5]. Especially in
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surgical disciplines, complex processes of change such as the introduction of new technologies, new surgical methods, or permanent changing surgical teams lead to high workload [6]. Further stressors might be e.g. intraoperative complications, inconsistencies in the surgical team, interruptions in work flow, hours of work, and personal characteristics such as fatigue, illness, or physical discomfort [4, 7–9]. The human response to the above mentioned stressors can be either of emotional, physical or mental nature or expressed by the individual behavior [4]. In the literature, occupational workload is known as a risk factor for the development of hypertension and coronary heart disease [10–14]. Therefore, the assessment of psychophysical workload in demanding work settings such as the surgical discipline is of particular interest. Likewise, evaluating workload is an important component of system design and analysis [3]. Given drawbacks of subjective assessment methods, by now, many researchers have turned toward measuring physical responses of surgeons for assessing their mental workload. While subjective workload measures attempt to quantify the effort exerted during task performance [3, 15], physiological responses to work provide more detailed and diagnostic information. For this reason, measurements should be based on various workload indices [2]. Associations between physiologic responses controlled by the sympathetic nervous system and mental stress experienced by the surgeon [7] support the idea of a complex methodology that combines both physical and psychological workload indicators. To ensure work flow in real-life investigations, short questionnaires that can be answered promptly should be adopted. Such assessment tools have proven their feasibility in terms of overall workload identification [16]. Surgeons have to adjust themselves to the daily workload and adapt to rapid changes. While single demands are to meet without difficulty, the combination of different loads can lead to a very high stress experience and—as a result—to human error [4, 17]. Special attention is given to the operating room (OR) as a place where great demands are made on the medical staff and where conflicts have to be solved quickly and successfully [6, 18, 19]. Since one-third of the daily working time of surgeons is dedicated to surgical procedures [1], this activity is of crucial interest when analyzing individual workload behavior. Procedural and decision errors have a major impact on the work and may be irreversible at worst. The intraoperative functioning of the surgeon is of major importance because of the great responsibility for the safety and the success of the treatment. First insights into the physiological workload responses of surgeons in the OR were given by Kuhn et al. who assessed workload by analyzing heart rate and sympatho-vagal balance taking into account the experience of the surgeon and his role in
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the OR [20]. The authors concluded e.g. that during surgery both primary operators as well as assistants responded with significantly increased heart rate (HR) compared to baseline HR. Furthermore, some researchers spotted that working as main surgeon can be considered as a potential stressor [11, 21–23]. However, so far it is not known whether the amount of intra-individual workload differs when operating as primary surgeon or assistant. This study determined whether there were any differences in psychophysiologic workload between the two roles, primary operator and assistant using an intra-individual study design with two measuring times. We hypothesized that in the role as primary operator, greater objective and subjective workload becomes evident than in the role as assistant.
Methods The prospective cross-sectional study was based on a psychophysiological 24-h monitoring with a total sample of 25 physicians from surgical disciplines. 24 men and one woman from two hospitals of Northern Germany took part voluntarily without financial reimbursement after having given their written informed consent. Eligibility criteria comprised sufficient language skills to ensure the comprehension of Ecological Momentary Assessments (EMA), absence of acute or chronic illnesses, and adverse drug status. Furthermore, a regular work day without shifts was required the day before monitoring as well as the ultimate day of investigation, respectively. Participants were given a written assurance of highly confidential handling of private data according to the guidelines for data privacy. The study was approved by the Ethics Committee of the Rostock University Medical Center (A2012-0075). Real-life monitoring approach Prior to monitoring, all subjects were informed about the study design and introduced in the handling of the mobile health system which has been developed in order to assess individual workload response wirelessly, continuously, and in real-time. All investigations were conducted in the real clinical setting and based on a multiparametric monitoring. The health monitoring (Fig. 1) comprised the recording of various physiological measures through a wireless sensor electronic module (FA. Hidalgo, Cambridge), and the documentation of work specifications and individual workload via smartphone. HR and breathing frequency (BF) were recorded continuously during the entire investigation. Three dry electrodes located in a chest belt enabled three channel ECG recordings. BF was obtained via an expansion sensor contained within the monitoring
Surg Endosc Fig. 1 Study design
belt. For online transmission and analysis, running average over 30 s period with a time resolution of four values per minute was calculated for both measures. Accuracy of data was screened using quality measures and information on signal confidence by the sensor. Additionally, the sensor provided information on body movement via a three-axis acceleration sensor and skin temperature by a thermistor located in the sensor module. All measures were sent to a HTC smartphone via Bluetooth. The smartphone was equipped with a mobile health application developed by the medical institution for documentation of daily activities and processing of EMA for subjective workload assessment [24, 25] (Fig. 2). Furthermore, it worked as a middleware, transferring all data to a communication server where data were stored, visualized, and post-processed.
the sum score as a global workload index because results were comparable to the weighted scales in terms of sensitivity [27, 28]. Due to the time constraints in the clinical setting and in order to increase user acceptance, in this study, the six dimensions were considered without former weighting process. The preoperative workload was assessed for reference purposes and acted as a basic value. It had to be evaluated for a determined period of 5 min right before start of surgery. Postoperatively, i.e., right after completion of surgical procedure, the intraoperative workload was assessed. Besides, subjects were asked to answer surgeryrelated questions regarding e.g. the degree of difficulty, the complication rate, the intraoperative role, or the wearing of lead aprons.
Ecological momentary assessments
Statistical analysis
The National Aeronautics and Space Administration Task Load Index (NASA-TLX) [26], which was validated in numerous studies [27], was implemented as an electronic version in the smartphone software and answered immediately before and after surgical procedures. It has been demonstrated that multidimensional assessment of perceived workload with the NASA-TLX rating scale is essential in order to capture the complexity of task effects on operators [28]. The NASA-TLX is a tool that provides an overall workload score based on the six subscales mental demand, physical demand, temporal demand, performance, effort, and frustration. While the original version provides for weighting of each dimension, in recent years, many researchers used the raw values of the subscales or
To determine intra-individual differences in psychophysical workload, only those ten surgeons who conducted both a surgery in the role of the primary surgeon and an operative procedure as an assistant were included in the analyzes. Three chiefs of medicine, three attendings, two fellows, and two residents formed the final sample of the study. The order of intraoperative roles as well as the time of surgery were predetermined by the plan of operation, and therefore in a random order which could not be modified. Analyzes of physical strain were based upon the two measures HR and BF. Furthermore, body movement was considered in order to evaluate HR and BF response. Skin temperature has not been respected for further analyzes because this parameter is subject to many confounders such
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Surg Endosc Fig. 2 Screenshots of software interfaces: Occupational tasks and physiological measures (A), NASA-TLX (B: Subscales 1–3, C: Subscales 4–6), category of surgery (D), degree of difficulty (E), and additional intraoperative information (F)
as ambient temperature, application of leads, or transpiration, and consequently it has to be considered with caution when interpreting workload. The data were analyzed with IBM SPSS Statistics 22.0 for Windows. Multivariate analyses of variance (Manova) were performed to evaluate the effects of intraoperative function on subjective and objective workload responses. Since fatigue raises workload [29] and employees are known to become more stressed over time [28], length of operating procedures was entered as covariate. All statistical tests were two-tailed with the alpha level set at 0.05.
Results The ten surgeons who acted in both functions on the day of monitoring were all male, were recruited at the age of 40.6 ± 9.1 years, and have been working for 10.3 ± 8.1 years in their job. Pre- and intraoperative subjective workload As can be seen from the absolute values in Table 1, in the role as primary surgeon, physicians appear to feel more stressed both before and after surgical procedures. In all
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workload dimensions, operating with higher responsibility led to higher workload scores. While the overall workload remained on an almost identical level when operating as primary operator (increase from pre- to postoperative EMA: 0.56 %), in their role as assistant surgeons’ total workload score decreased by 24.6 % from pre- to postoperative evaluation. However, when considering length of surgeries as possible workload determining factor in the multivariate analysis, the results indicate that none of the NASA-TLX workload dimensions related to the intraoperative role but to duration (Table 2). Thus, the hypothesis of a higher workload when operating with higher responsibility cannot be confirmed. There is only a tendency for preoperative effort (p = 0.096; g2 = 0.155) and NASA-TLX sum score (p = 0.092; g2 = 0.158) to be higher when operating in the role with higher responsibility. In contrast to intraoperative job role, length of surgeries had a significant impact on intraoperative physical demands (p \ 0.05; g2 = 0.283), temporal demands (p \ 0.05; g2 = 0.260), effort (p \ 0.05; g2 = 0.287), and NASA-TLX sum score (p \ 0.01; g2 = 0.287). Furthermore, preoperative physical demand (p \ 0.095; g2 = 0.155) and intraoperative performance (p = 0.096; g2 = 0.154) tended to increase with longer operation duration (Table 1).
Surg Endosc Table 1 Absolute values of pre- and intraoperative subjective workload in both functions (n = 10) Time of assessment
NASA-TLX subscale
Preoperatively
Mental demand
Postoperatively
Primary surgeon M ± SD 55.4 ± 22.4
Assistant M ± SD 35.6 ± 18.3
Physical demand
49.5 ± 24.4
35.5 ± 17.4
Temporal demand
59.4 ± 23.7
42.2 ± 24.7
Performance
48.8 ± 26.6
32.6 ± 27.3
Effort
57.1 ± 18.2
37.6 ± 15.9
Frustration P NASA-TLX
34.1 ± 21.4
14.5 ± 14.1
304.3 ± 82.0
198.0 ± 80.3
Mental demand
65.9 ± 25.3
30.9 ± 23.0
Physical demand
50.4 ± 23.1
30.2 ± 19.7
Temporal demand
64.4 ± 21.6
35.1 ± 20.5
Performance
38.9 ± 32.3
17.7 ± 27.3
Effort
62.2 ± 27.4
27.0 ± 15.0
Frustration P NASA-TLX
24.2 ± 22.3
8.4 ± 9.1
306.0 ± 110.6
149.3 ± 75.7
Descriptive statistics: M mean, SD standard deviation. All subscales of NASATLX were rated from 0 to 100
Intraoperative physical workload A differentiated view on the physiological parameters revealed no differences in HR (p = 0.668; g2 = 0.011) and BR behavior (p = 0.967; g2 = 0.000) for both surgical roles. Length of surgeries tended to have an impact on intraoperative HR (p = 0.72; g2 = 0.178) but not on BR (p = 0.147; g2 = 0.120). Figure 3 and 4 show the level of intraoperative physical workload in both functions.
Discussion In the presented investigation, we used the cross-sectional data of a particularly burdened work group to examine the effects of the intraoperative function on psychophysical workload using a mobile health system. The OR has a special meaning since it represents the central element of each hospital. Often, the lives of patients depend on the services provided in the OR. The large responsibility of the surgeon for the safety and success of patient care is attended by a high workload level of the surgeon. Excessive workloads lead to mental and physical exhaustion, fatigue, and sleep deprivation which may increase the likeliness of medical errors [30–32]. Against the background of an impairment of patient care by factors such as time pressure or overload [33], and the deterioration of health status and well-being due to increasing work densification [10, 34], the study of surgeons intra-individual workload is of particular importance for scientific and
occupational health reasons, respectively. By looking at the individual workload response, researchers get an insight into work exigencies and can develop new health care approaches for employees. To date, several methods for measuring the workload of surgeons in the OR have been applied in order to derive strategies for dealing with high intraoperative physical and mental workload [7]. While some researchers have focused on subjective strain assessment [35], other scientists analyzed cardiac responses [11, 36, 37], or chose a combination of subjective and objective methods [38–40] to identify individual workload responses during different types of surgery or in differently equipped ORs. Many of the previous studies have been limited to simulations in which a virtual environment for special surgical situations has been created due to the difficulty of applying real-time studies in such demanding work settings. Studies that allow for a continuous measurement of physical responses and a mobile recording of subjective workload under everyday working conditions are rare [30]. The advantage of telemedical workload assessment lies in the autonomy of the participants. After oral and written instruction, the presence of the investigator is no longer required. The system collects, processes, and transmits all data wirelessly and in real-time [24] so that the compliance of the subject is the major determining factor in terms of data completeness and data quality [16, 41]. As our results clearly indicate, both the subjective as well as the objective measures do not support the hypothesis of psychophysical workload differences depending on the intraoperative role. In contrast, the multivariate analysis revealed that higher intraoperative workload can be attributed particularly to operation duration. These results confirm earlier findings of changes in workload over task duration indexed by the NASATLX or the Dundee Stress State Questionnaire [28, 42, 43]. In our study, physical demands, temporal demands, and effort emerged as the principal contributors to intraoperative workload. Other researchers found frustration or mental demand to be the leading influencing factors in vigilance tasks [28]. Effects of time on task have mostly been studied in laboratory experiments, and therefore do not adequately reflect realworld effects and often do not reach realistic working time. Thus, the present study makes a contribution to the understanding of workload in different job roles as well as workload changes over time in a naturalistic setting. Since surgery length and not intraoperative function plays a significant role during surgical procedures in our study, the concept of breaks as the ‘‘oldest method to counteract fatigue’’ and to work successfully [44] has to be taken into account. Engelmann and his associates recently summarized that short breaks within surgery decreased the workload of physicians and improved the concentration significantly. The reduced overall workload was explained
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Surg Endosc Table 2 Effects of intraoperative job role and surgery length on perceived workload. Results based on multivariate analyses (n = 10)
Workload Indicator Intraoperative Role
Preoperatively
Intraoperatively
Length of surgery
Preoperatively
Intraoperatively
Fig. 3 Intraoperative heart rate in the role as primary surgeon and assistant
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df
F
p
Partial g2
Mental demand
1
2.643
0.122
0.135
Physical demand
1
0.000
0.984
0.000
Temporal demand
1
0.099
0.757
0.006
Performance
1
0.260
0.617
0.015
Effort
1
3.107
0.096
0.155
Frustration P NASA-TLX
1
3.180
0.092
0.158
1
2.182
0.158
0.114
Mental demand
1
1.936
0.182
0.102
Physical demand
1
0.005
0.947
0.000
Temporal demand
1
0.971
0.338
0.054
Performance
1
0.006
0.942
0.000
Effort
1
1.700
0.210
0.091
Frustration P NASA-TLX
1
0.274
0.607
0.016
1
1.375
0.257
0.075
Mental demand Physical demand
1 1
0.008 3.128
0.930 0.095
0.000 0.155
Temporal demand
1
1.792
0.198
0.095
Performance
1
0.509
0.485
0.029
Effort
1
0.017
0.899
0.001
Frustration P NASA-TLX
1
0.003
0.960
0.000
1
1.136
0.301
0.063
Mental demand
1
2.939
0.105
0.147
Physical demand
1
6.716
0.019
0.283
Temporal demand
1
5.969
0.026
0.260
Performance
1
3.098
0.096
0.154
Effort
1
6.856
0.018
0.287
Frustration P NASA-TLX
1
2.676
0.120
0.136
1
12.211
0.003
0.418
Fig. 4 Intraoperative breathing frequency in the role as primary surgeon and assistant
Surg Endosc
as a consequence of reduced fatigue. Moreover, performance could be sustained without a prolongation of operation time which was very surprising. Taking into consideration the important findings of Engelmann et al. and our results which evidenced that the operation duration is a major influencing factor of surgeon’s workload during surgeries, the public attention should be insistently directed to the suggestion of regular breaks during surgery [45]. In this context, the modification of the surgical management would be a milestone. So far, the surgical management was implemented in German hospitals to increase the efficiency of surgeries for economic reasons. Currently, the German Association for Surgical Management (VOPM) recommends the following key data for a benchmarking: morning start, incision-to-suture time, changing time, and degree of utilization of OR. Until today, individual needs such as psychophysical workload have not been considered in optimization processes. Possibly, a regular break scheme could reduce individual workload responses, optimize employees’ satisfaction, avoid chronic stress, and after all, increase the performance of the surgical team in the long term. Even if in this study only short-term effects of intraoperative workload have been measured, and thus, healthrelated consequences cannot be implied automatically, we assume that chronic high workload conditions in the OR will have a negative impact on health and well-being. There have been limitations of this study that have to be mentioned. Firstly, time-precise answering of EMA depended on the compliance of surgeons. Since EMA were initiated by selection of the appropriate activity in the activity protocol by the surgeon themselves, retardation of data entries could not be excluded. Due to the self-completion of the activity protocol, length of procedures might have also varied a little. Even if ambulatory assessment has many advantages, the reliability of data collection is limited because field studies are only partially controllable [46–49]. Moreover, it should be kept in mind that answers to survey questions can be affected by working memory and the ability in judging task difficulty [7, 40]. The second limitation was the low capacity of smartphone batteries due to continuous data transfer. Subjects were asked to apply additional chargers in case of empty batteries. This could have reduced the wearing comfort of the mobile health system, even if subjects did not mention this in the oral retrospective survey [16]. As with any indirect measure of BF, in the case of measuring breathing via expansion, body motion, activity, or speaking can cause measurement artifacts that can reduce the accuracy of recorded data. After this study has been completed in 2011, a new version of NASA-TLX, the surgery-specific workload index SURG-TLX has been developed and validated. In
future studies, this assessment tool should be used since it has proven to be sensitive to different sources of stress [50].
Conclusion Multidimensional mobile health systems can be a useful tool for assessing the psychophysical workload even in demanding occupations. The present study is supposed to be a contribution to an objectification of psychophysical workload in surgical hospital doctors. The results disprove that working in the role as primary surgeon is associated with higher perceived workload and higher objectively measured cardiopulmonary responses. However, analyzes have shown that operation duration has a major impact on the perceived workload. In order to avoid chronic overload and chronic health threat, the consideration of intraoperative breaks in the surgical management is suggested. Acknowledgments The authors are very grateful to the reviewers for their valuable comments and suggestions. This study was realized as part of the project eHealth MV, funded by the State of Mecklenburg-Western Pomerania in Germany as well as by the Federal Ministry of Education and Research (BMBF) in the program ‘‘Center for Innovation Competence (ZIK)’’. Disclosures Drs. Rieger, Fenger, Neubert, Weippert, Kreuzfeld, and Prof. Stoll have no conflicts of interest or financial ties to disclose.
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