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Design and ergonomic assessment of an infusion set connector tool used in nursing work
Applied Ergonomics 75 (2019) 91–98
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Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo
Design and ergonomic assessment of an infusion set connector tool used in nursing work
T
Ehsan Garosia, Adel Mazloumia,b,∗, Reza Kalantaric, Zahra Vahedia, Zahra Shirzhiyand a
Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Iran Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran c Department of Ergonomics, School of Health, Shiraz University of Medical Sciences, Iran d Department of Biomedical Systems & Medical Physics, Tehran University of Medical Sciences, Iran b
A R T I C LE I N FO
A B S T R A C T
Keywords: Ergonomic design Infusion set Nursing
Nursing is a physically demanding job characterized by a high prevalence of fatigue and musculoskeletal disorders. One of the high-exertion and repetitive nursing tasks is the manual connection of an infusion set to a medical fluid bottle. Such physical work can be eased by the design of new hand tools. Correspondingly, this study designed and ergonomically assessed an infusion set connector tool (ISCT) and compared it with that of manual connection. First, a prototype of ISCT was designed to perform infusion set connecting task in the mechanical form. Subsequently, 12 nurses were asked to connect an infusion set to medical bottle in the form of manual and mechanical tasks and these tasks were evaluated using ergonomic indices including muscular activity level, force, posture, and subjective (Borg scale CR10) measures. Results showed that the activity levels (root mean square) of the extensor digitorum communis, flexor carpi radialis, biceps, triceps, and deltoid muscles remarkably decreased when the nurses used the ISCT. The postures of the wrist, arm, and shoulder regions were corrected from Rapid Upper Limb Assessment action level 3 to 2 when the designed tool was used. Additionally, the subjective perception of exertion was significantly lower with the use of the prototype.
1. Introduction Nursing is a physically and psychologically demanding profession with a high prevalence of musculoskeletal disorders (MSDs) as indicated in several studies (Choobineh et al., 2010; Magnago et al., 2010; Menzel, 2007; Smith et al., 2003, 2006). Daraiseh et al., for example, reported that MSDs most frequently occur in the back, neck, and shoulders, followed by the upper back, hands/wrists, and knees/lower legs (Daraiseh et al., 2003). In Iran, the prevalence rates of low back, knee, shoulder, and neck pain were 73.2%, 68.7%, 48.6%, and 46.3%, respectively (Mehrdad et al., 2010). MSDs are also often cited as the reason for sickness-related absences and the high turnover of nurses (Blekesaune and Solem, 2005; Menzel, 2008). Nurses' working conditions usually differ across countries, regions, and hospitals (Simon et al., 2008). These differences are attributed mainly to the provision of instruments and the quality of process management in hospitals. Nurses are involved primarily in the administration of medications in hospital wards and other relevant settings (Raju et al., 1989). As a subset of medication administration,
intravenous (IV) administration is routinely performed by nurses and widely used in hospitals for the transmission of fluids, including blood, drugs, and food in liquid form. The standard infusion equipment for IV administration consists of a bottle or bag containing a medical fluid for dispensation, a plastic administration set, and a suitable needle for insertion into a patient's vein (Flack and Whyte, 1974). Inserting a plastic administration set into a medical fluid container is part of the preparation and administration of IV medication. This task is performed in a manual way by nurses. In intensive care units in particular, the use of maintenance medical fluid is common over one work shift (Bihari et al., 2016), thereby increasing the frequency with which infusion sets are connected. In manual infusion set connecting (ISC) task, nurses usually hold the bottle by one hand and push the infusion set with another hand to make a hole and insert it to the bottle in a specific position. Fig. 1 shows how the task is done by a nurse. In our experience, inserting the infusion set requires a significant gripping force and unnatural flexed and twisted postures of the hand. In the workstation with high height, the shoulder posture is considerable too. Awkward posture and excessive muscular
∗ Corresponding author. School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences, P.O. BOX: 6446, Tehran 14155, I.R, Iran. E-mail address: [email protected] (A. Mazloumi).
https://doi.org/10.1016/j.apergo.2018.09.008 Received 24 November 2017; Received in revised form 12 September 2018; Accepted 12 September 2018 0003-6870/ © 2018 Published by Elsevier Ltd.
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Fig. 1. Manual infusion set connecting task.
improvements to physically demanding tasks in nursing, the aim of this study was to design a new tool and to compare its physical demand and risk to the manual method. It is hypothesized that by designing such ergonomic tool and using it in ISC task, required force and muscle activity will be decreased significantly. Meanwhile, the awkward handarm posture will be improved by using this tool. Indeed, the idea of applying a hand tool for ISC task originated from one of the researchers’ experiences in nursing work. He is a practicing nurse in an Iranian hospital and a researcher focusing on ergonomics in healthcare.
force in manual tasks can be considered risk factors for the development of upper extremity disorders among nurses as they accomplish physical tasks (Li, 2002). Previous researches, including that conducted by (Mital and Kilbom, 1992; Punnett and Wegman, 2004), indicated that the use of arms and hands at an awkward posture and frequent motions of hands/wrists are associated with pain and discomfort. Other studies reported that flexion, extension, and radial and ulnar deviation in the wrist are related to carpal tunnel syndrome (CTS) in many professions (Armstrong and Chaffin, 1979; Tanaka et al., 1995). Moreover, in some studies, exposure to factors involving long duration, force, and awkward postures are known as the main physical risk factor for MSDs development (Gallagher and Heberger, 2013; Hoogendoorn et al., 1999). Improving ergonomic factors, such as the design of tool and equipment, work environments, or both, and training workers in ergonomic principles are expected to reduce the risk of developing MSDs (Hoe et al., 2012) and ease physically demanding nursing tasks. The excellent ergonomic design of medical devices are necessary for guaranteeing safety for both patients and clinical care workers (Martin et al., 2008). Hand tool design/redesign plays an important role in easing the demands of manual work and controlling problems in duties that involve the use of hands and forearms and improves user job satisfaction (Kadefors et al., 1993a; Sperling et al., 1993). Medical tools and devices with ergonomic features also reduce muscle exertion because these instruments decrease the physical demands imposed when people carry out repetitive tasks (Gauthier and Lagacé, 2015; Kim, 2012). Given the necessity of designing new tools for necessary work
2. Methods An experimental study was carried out to evaluate manual and mechanical ISC tasks. In this mean, an infusion set connecting tool (ISCT) was designed and used to perform the mechanical ISC task. 2.1. Design of the ISCT To achieve an ideal design which meets our goals, the idea of developing an ISCT was shared with an industrial design group. As mentioned earlier, among ergonomic risk factors, force is the main problem perceived by nurses during the manual ISC task. To solve this problem and to ensure the functional performance of the tool, the firstclass lever model was used in the primary design. Another concern for manual ISC task was awkward posture in the hand and arm regions. In order to correct this problem, a handle (110 mm, length) in conjunction with a trigger (35°-angle to handle) was attached at the bottom of the main body of the ISCT. (Figs. 2 and 3). 92
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Fig. 2. The sketch of ISCT; A: right view, B: trimetric view.
Fig. 4. Prototype of the ISCT and medical fluid bottle; 1: Infusion set frame, 2: Handle, 3: Trigger, 4: Spring, 5: Infusion set, 6: Medical bottle holder, 7: Medical fluid bottle.
Fig. 3. Three-dimensional view of the ISCT.
2.4. Manual and mechanical ISC tasks
2.2. Prototyping
To connect the infusion set to the medical fluid container, nurses usually hold the container by one hand and insert the infusion set with another hand in a specific position on top of the container. This task requires forceful exertion associated with the gripping and bending of the wrist. Fig. 5 illustrates how the manual ISC task is accomplished. Mechanical ISC task is done by insertion of an infusion set into the medical bottle using ISCT with the following instruction: To use the ISCT first, an infusion set is placed on a specified frame (Fig. 4, item 1), intended for the set. Subsequently, the bottle holder (Fig. 4, item 6) is attached to a medical fluid bottle, and pushing the trigger (Fig. 4, item 3) moves the infusion set forward and enables insertion into the bottle. Detaching the ISCT is easily accomplished by pulling up the device. Fig. 6 illustrates how the mechanical ISC task is executed. A close-up view of manual and mechanical ISC tasks is shown in Fig. 7. The result of a simple task analysis for manual and mechanical ISC tasks was detailed in Table 1.
SolidWorks version 2016 was used to sketch and render the ISCT in three-dimensional form. Figs. 2 and 3 show the sketches and a threedimensional view of the ISCT, respectively. On the basis of the final format of the simulation and the detailed drawing, the prototype of ISCT was made (Fig. 4). Aluminum metal was applied a material to building the prototype. Design dimension is showed in Fig. 3 and the prototype weight is 300 g. This newly developed prototype was registered as a patent in the Iranian Intellectual Property Organization (IIPO), with a registration number of 85545 (Garosi and Kalantari, 2014). Fig. 4 shows a detailed illustration of the ISCT and a medical fluid bottle. 2.3. Final design The prototype form of ISCT was used in all the ergonomic assessments in this work. The final design will be completed considering further formative assessment and summative evaluation of the prototype. 93
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participation in the is study. (Means & SD age: 28 years ± 6.5, weight: 67 kg ± 11.7, stature 1710 mm ± 97). Only right-handed nurses were selected to avoid the influence of hand preference on the survey. All the participants were healthy and did not report any injuries or MSDs. They completed and signed informed consent forms before the initiation of the experiments. 2.6. Procedure A laboratory experiment was set up, and ISC tasks were simulated in a manner similar to how the connection is performed by the nurses in their daily work. An instruction (section 2.4 Mechanical ISC task) was given to the subjects to become familiar with the use of the ISCT and they also participated in a training session and practiced the mechanical ISC task until they were satisfied. Two experimental sessions were set up in one day for each participant. During each session, they were asked to perform the manual or mechanical infusion set connecting task in a randomized order. In order to improve statistical analysis power, the subjects were asked to repeat each of the manual and mechanical tasks 3 times, with a 5-min rest between each session. A same brand of the standard infusion set and a commonly used rectangular medical fluid bottle was used for each trial of the manual and mechanical tasks. As mentioned above, the ISC tasks, simulated in this study was analogous to that conducted in real work conditions. The workstation was adjusted using a base and a wooden platform to provide dimensions similar to those of a real workstation. The height, length and width of the simulated workstation were 95, 60, and 35 cm, respectively, identical to those of an infusion trolley.
Fig. 5. Manual ISC task, worst-case deviation in the upper extremities and trunk body regions.
2.7. Ergonomic assessment of manual and mechanical ISC tasks In this study different ergonomic assessment techniques were used. The subjective assessment was conducted by the Borg scale CR10 (Borg and Kaijser, 2006). Moreover, measures such as electromyography (EMG) and force were applied for objective evaluation under the manual and mechanical tasks. Also, an observational survey based on the Rapid Upper Limb Assessment (RULA) technique (McAtamney and Corlett, 1993) was used for posture assessment in this study. 2.7.1. Subjective assessment Borg scale CR10 was used in the subjective evaluations of perceived exertion. The scale was given to the subjects at the end of each task completion, with the following instructions: “You do not have to specify your feelings, but do select the number that most correctly reflects your perception about physical demands of inserting the infusion set to medical fluid bottle. If you feel no loading, you should answer zero, nothing at all. If you start to feel something just noticeable, your answer is 0.5, extremely weak. If you have an extremely strong impression, your answer will be 10. So, the more you feel, the higher the number you are choosing. Keep in mind that there are no wrong numbers; be honest, do not overestimate or underestimate your ratings” (Borg and Kaijser, 2006; Kroemer and Kroemer, 1997). 2.7.2. EMG assessment A surface bipolar EMG (g-USBamp, made in Austria) was used to measure muscle activity during the manual and mechanical ISC tasks. After appropriate skin preparation, two active Ag/AgCl ring electrodes were attached to the skin using a double-sided tape with a center-tocenter distance of 20 mm. The specific locations of attachment were the participants’ right-side muscles, namely, the extensor digitorum communis (EDC), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), biceps, triceps, and deltoid muscles. Electrode placement was performed in accordance with the protocols of the Surface Electromyography for the Non-Invasive Assessment of Muscles and the ABC of EMG (Hermens et al., 2000; Konrad, 2005). The target muscles were selected using a muscle activation examination during ISC tasks in
Fig. 6. Mechanical ISC task, worst-case deviation in the upper extremities and trunk body regions.
2.5. Participants Twelve nurses (six males and six females) were recruited for 94
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Fig. 7. Close-up view of the manual (A) and mechanical (B) ISC tasks.
measure the force required to insert the infusion set to a medical fluid bottle. In the manual connection mode, the proximal side of the infusion set was fixed onto the probe of the dynamometer for the measurement of the required force. In the mechanical connection mode, the probe of the dynamometer was fixed onto the handle of the ISCT, after which the force required to insert the infusion set to a medical fluid bottle was measured and registered. Force was measured by researchers three times each in the manual and mechanical connection, and the maximum force among the measurements was considered in the evaluation and mean calculation.
a pilot study. The muscle selection for examination was based on some similar preceding studies (Freund et al., 2000; Kadefors et al., 1993b; Yoo, 2013; You et al., 2005). A ground electrode was placed at the distal end of the lateral side of the radial bone. EMG signals were recorded at a sampling rate of 1200 Hz. An online bandpass filter with a cut of frequencies of 0.5 and 500 Hz was applied during signal recording. Before the nurses performed the ISC tasks, the maximum voluntary contractions (MVCs) of the target muscles were performed and the EMG signal of MVC task was recorded for each muscles group, the MVC was done 3 times to enhance statistical power with a 5-min rest between contractions; each contraction took almost 8 s. EMG signal processing: the recorded EMG signals were preprocessed by applying an offline Butterworth bandpass filter with the order of 4 and the cutoff frequencies of 1 and 250 Hz for removing any possible low frequencies artifacts like the baseline offset and wanderings, and high-frequency artifacts. for this purpose, we use fdesign Matlab object for specifying a bandpass filter and use filtfilt Matlab function which applies the specified filter with zero phase shift. For all trials in MVC, manual and mechanical tasks, the EMG activation interval was extracted offline by visual inspection as shown in Fig. 8. After identifying the onset and offset time the RMS of selected part of EMG signal was calculated using Matlab RMS function. Then the mean of RMS values in 3 trials of MVC, are calculated and the mean RMS values in the manual and mechanical task were normalized to mean RMS value derived from MVC task in target muscles. The described procedures for signal processing were done in the build-in functions in MATLAB R2014a software.
2.7.4. Posture evaluation using RULA Ergonomic risk factors were assessed during the manual and mechanical ISC tasks through direct observation based on RULA (McAtamney and Corlett, 1993). The simulated manual ISC task for posture evaluation is similar to the actual task performed in a hospital, as stated in the “task selection.” The main criteria for posture selection in the manual and mechanical connection were the worst cases (maximum range of motion) in viewpoint of maximum flexion, deviation and rotation of the hand and wrist areas during the assessment of posture as the nurses completed the manual ISC task. Posture assessment was carried out by the examiners, as ergonomic specialists and the worst cases were determined through direct observation of the postural deviations during tasks implementation. 2.8. Statistical analyses Before data analyzing, Kolmogorov–Smirnov test was used to determine data distribution normality. Wilcoxon signed-rank test was done to compare muscle activity level and subjective Borg scale data for the manual and mechanical ISC tasks. A p-value of less than 0.05 was
2.7.3. Required force measurement A portable dynamometer model (Mecmesin, basic force gauge, high accuracy ± 0.25%, sample rate 1000 Hz, made in USA) was used to Table 1 Manual and mechanical ISC subtasks. Subtasks in manual connection 1) 2) 3) 4)
Unpacking the infusion set Removing the cover (cab) of the infusion set Putting the medical fluid bottle on the station Taking and holding the infusion set using the dominant hand and the medical fluid bottle using the other hand 5) Inserting the infusion set to the medical fluid bottle by pushing it along the vertical axis 6) Releasing the hand from the Infusion set
Subtasks in mechanical connection 1) 2) 3) 4)
Unpacking the infusion set Removing the cover (cab) of the infusion set Putting the medical fluid bottle on the station Taking and holding the infusion set and placing it in the ISCT using the dominant hand and the medical fluid bottle using the other hand 5) Attaching the tool to the medical fluid bottle and pushing the handle of the tool to enable infusion set insertion into the bottle 6) Releasing the ISCT from the medical fluid bottle
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Fig. 8. The EMG activation of the Flexor Carpi Radialis (FCR) muscle, obtained from participant number six.
considered statistically significant.
Table 3 Results of Wilcoxon signed-rank test on EMG (%MVC).
3. Results The results showed significant differences between the objective and subjective measurement variables. The overall results of the subjective assessment indicated that the degree of perceived exertion significantly differed (p = 0.002), as indicated by the mean values derived from the Borg scale for ISCT-assisted connection, 2.3 ( ± 0.49), and manual connection, 5 ( ± 1.20). The Borg scale data for the 12 participants are summarized in Table 2. The results related to muscular strain measured by surface EMG (% MVC) in the manual and mechanical modes are presented in Table 3. The Kolmogorov–Smirnov test showed that the distribution of EMG signals and data was non-normal. Therefore, the Wilcoxon signed-rank test was carried out to compare muscle activity level, Borg scale data, and force in the manual and mechanical ISC. The muscle activity of each muscle group decreased in the mechanical ISC, and the most strongly activated muscles in both the manual and mechanical connection were the EDC and FCU. The Wilcoxon test also revealed significant differences in the muscular activity of the EDC, FCR, biceps, triceps, and deltoid muscles between the two ISC methods. Muscular activity was significantly higher during the manual ISC. Regarding the maximum amount of force to do the tasks, the armhand force to insert the infusion set to the bottle was (mean ± SD): 112.16 ± 5.62 N, in the manual ISC task. In the mechanical task, the amount of hand grip force to insert the infusion set into the bottle was measured (mean ± SD): 49.16 ± 6.82 N, using ISCT. The findings on posture assessment during ISC tasks are presented in Table 4. The median value of the final RULA score for the right side of the body during the manual connection was 6, whereas the median value for the same side of the body during the mechanical connection was 3. The action level with respect to the manual connection was 3, which changed to 2 during the mechanical connection. The action level on the left side of the body was the same under both the connection
Mean score
SD
p value
Manual connection Mechanical connection
5 2.33
1.20 0.49
0.002
Manual connection Mean ± SD
Mechanical connection Mean ± SD
p value
Extensor Digitorum Communis Flexor Carpi Radialis Flexor Carpi Ulnaris Biceps Triceps Deltoids
59.44 ± 14.97
36.28 ± 9.71
0.002
44.2 47.5 37.1 55.3 31.6
25.1 ± 11.25 38.03 ± 19.13 15.90 ± 11.60 27.23 ± 17.97 14.55 ± 10.85
0.003 0.08 0.003 0.005 0.003
± ± ± ± ±
21.59 18.02 26.68 16.66 16.99
methods.
4. Discussion The main aim of this study was to determine the ergonomic advantages of a newly developed ISCT over the manual connection of infusion sets. This tool was designed based on the ergonomic principles and assumption of force and posture correction in hands and arms. The data analyses reflected ergonomic improvements in force, posture, and personal perception when the ISCT was used to connect infusion sets to medical fluid bottles. The subjective evaluation showed a significant easing of the ISC task when the developed ISCT was used by the nurses. No similar or relevant studies have been conducted with respect to the subjective assessment of manual ISC. As indicated in previous studies, manual tasks require more physical exertion and may lead to target muscle fatigue and increase heart rate (Borg, 1985; Ulin et al., 1993). This issue may be the reasons why the participants’ subjective perception of exertion was higher during the manual connection than during the mechanical task completion. Another important difference was in the muscle activity level. The surface EMG recording in the current work showed that all the six target muscles were active during the mechanical and manual connection tasks but that the EDC and FCU muscles were the strongest activated muscles in the manual and mechanical connection, respectively. EMG has been identified as a major quantitative measure for studying cumulative trauma disorder (Li, 2002) and a technique for evaluating and recording the electrical activity produced by skeletal muscles (Husain et al., 2013). The findings in the current study are
Table 2 Borg scale results on manual and mechanical ISC (N = 12). Task
Muscle
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Table 4 Results of posture evaluation for each side of the body during manual and mechanical ISC. Tasks
Body side
Score A
Score B
Score C
Score D
Final score
Action level
Manual connection
Right Left Right Left
5 2 3 2
2 2 2 2
8 2 4 2
3 3 3 3
6 3 3 3
3 2 2 2
Mechanical connection
Score A: Posture of arm and wrist; Score B: Posture of neck, trunk, and leg; Score C: Force and frequency in A region; Score D: Force and frequency in B regions; Final score: The final score is calculated based on table C in RULA score sheet; Action level 1: acceptable posture; Action level 2: Further investigation is needed, and changes may be required; Action level 3: Investigation and changes are required soon; Action level 4: Investigation and changes are required immediately.
required to complete the mechanical connection was 0.86 s longer than the time to complete the manual connection. Although this variable was not reported and considered as the main objective in this study, it can be interpreted that such kind of trade-off should be regarded in the selection and applying any hand tools like ISCT. The little longer time here may be shortened by training sessions. According to Oulasvirta study “the inferior performance of the novices must be accounted for their lack of device-specific experience (Oulasvirta et al., 2011).
attributed to the anatomical muscular function executed in each task (Ghosh, 2007). The Wilcoxon analysis showed a significant difference in muscular activity between the two ISC methods. The muscular activity (%MVC) of all the target muscles, except FCU, which was lower with the use of the ISCT than with the manual connection. Although the difference in FCU muscle activation was not statistically significant, an important issue for consideration is that such variance may be due to the lower muscle activity of two participants in the manual connection than in the mechanical connection. This effect may be related to the mismatch between the ISCT handle and the participants’ anthropometric dimensions. The findings are in line with those of previous studies that reported significant differences in hand muscle activity after the design and redesign of a new hand tool (Li, 2002; Sancibrian et al., 2014). Regarding the force measured for inserting the infusion set to the bottle, the subjects were compelled to apply a force greater than 100 N to accomplish the manual connection. This force was significantly decreased by 49.16 N through use of the ISCT. A reduction of more than fifty percent in the required force is remarkable in this case. This level of force is less than 10 percent of maximum grip strength of dominant hand in the Iranian men aged 20–24 years and women aged 35–39 years (Mohammadian et al., 2014). The body postures of the nurses were evaluated via RULA. The RULA scores for the participants’ arm/wrist (score A) and neck/trunk/ legs (score B), as well as their final scores, were high as they performed the manual ISC (Table 4). During the manual connection, the upper and lower right arm of the participants were in an awkward and abducted posture. The right wrist was flexed with a twisted posture, and the left hand, which is used to hold a medical fluid bottle was in a natural posture in both the manual and mechanical connection tasks. In the mechanical connection, the posture of the right arm and wrist improved, and the action level changed from 3 in the manual task to 2 in the mechanical tasks. Hignet demonstrated that working with hospital equipment requires harmful postures for more than 50% of the time (Hignett, 1996). As reflected in the posture evaluation in the present study, the manual ISC was carried out with poor posture. This problem requires further investigation and addressing in the near future to prevent injuries. In this research, changing from manual connection to mechanical task completion corrected posture. Note, however, that posture correction using the ISCT was observed in a single work context with a fixed workstation height of 85 cm (the same as the standard trolley height). In cases wherein the heights of trolleys differ, the posture of users may also vary, and the effects of the ISCT may change. Therefore, trolley height should be ergonomically adjusted before work is carried out on it. Nevertheless, with the final anthropometric design of the novel ISCT, along with the provision of training and guidelines, improvement in posture and ease of use are expected. Moreover, the ISCT can work with other types of infusion sets and bottles and can be universally useful for a variety of sets/bottles by changing the medical bottle holder (Fig. 4, part 6) into an adjustable version. What is more, a small difference of less than 1 s was found between the two connections methods in terms of the time required to complete the tasks. Despite the fact that ISCT could improve the infusion task from the viewpoints of required force and body posture, the time
5. Conclusion Considering that the manual connection of infusion sets is not an ergonomic task for nurses working in hospitals, a necessary requirement is to improve task completion by introducing a new ergonomic hand tool. Accordingly, this study developed a patent-pending ISCT and evaluated the tool from different ergonomic viewpoints. The ISCT could significantly reduce the force and muscle activity during performing ISC task and improved body posture. In general, ergonomic interventions, such the design of new tools, are a practical approach to controlling musculoskeletal risk factors and providing a safe and healthy workplace for nurses. 6. Limitations of the study The current study had some limitations. First, all the ergonomic assessments were conducted using a prototype form of the ISCT. Using an optimized and final ISCT design would provide summative results and enhance ease of use among nurses. Second, one type of medical fluid bottle was used in the ISC tasks. Hence, the physical demands for infusion set connection task may vary because of differences in the quality, shape, and material of medical fluid containers. Working with other types of bottles would be helpful in informative assessment of the ISCT. Lastly, they were likely some investigators biases due to unsynchronized and manual methods of data collection and analyses. Acknowledgments This article was developed under the framework of Project Noe30454, at Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences and Health Services. The authors thank all participants for their kind corporation in this study and also Mr. Mojtaba Ahmadi for the 3D design. References Armstrong, T.J., Chaffin, D., 1979. Carpal tunnel syndrome and selected personal attributes. J. Occup. Environ. Med. 21, 481–486. Bihari, S., Watts, N.R., Seppelt, I., Thompson, K., Myburgh, A., Prakash, S., Bersten, A., 2016. Maintenance fluid practices in intensive care units in Australia and New Zealand. Crit. Care Resuscitation 18, 89. Blekesaune, M., Solem, P.E., 2005. Working conditions and early retirement a prospective study of retirement behavior. Res. Aging 27, 3–30. Borg, E., Kaijser, L., 2006. A comparison between three rating scales for perceived exertion and two different work tests. Scand. J. Med. Sci. Sports 16, 57–69. Borg, G., 1985. An Introduction to Borg's RPE-scale. Movement Publications, Ithaca. Choobineh, A., Movahed, M., Tabatabaie, S.H., Kumashiro, M., 2010. Perceived demands
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and musculoskeletal disorders in operating room nurses of Shiraz city hospitals. Ind. Health 48, 74–84. Daraiseh, N., Genaidy, A.M., Karwowski, W., Davis, L.S., Stambough, J., Huston, R.I., 2003. Musculoskeletal outcomes in multiple body regions and work effects among nurses: the effects of stressful and stimulating working conditions. Ergonomics 46, 1178–1199. Flack, F., Whyte, T., 1974. Behaviour of standard gravity-fed administration sets used for intravenous infusion. Br. Med. J. 3, 439–443. Freund, J., Takala, E.-P., Toivonen, R., 2000. Effects of two ergonomic aids on the usability of an in-line screwdriver. Appl. Ergon. 31, 371–376. Gallagher, S., Heberger, J.R., 2013. Examining the interaction of force and repetition on musculoskeletal disorder risk: a systematic literature review. Hum. Factors 55, 108–124. Garosi, E., Kalantari, R., 2014. Infusion set connector device (portable infusion set connector device to the medical fluid bottle). In: Iran, i.p.c.o. (Ed.), A61K,B65 ed, Iran. Gauthier, F., Lagacé, D., 2015. Critical success factors in the development and implementation of special purpose industrial tools: an ergonomic perspective. Procedia Manuf. 3, 5639–5646. Ghosh, B.D., 2007. Human Anatomy for Students. Jaypee Brothers Medical Publishers. Hermens, H.J., Freriks, B., Disselhorst-Klug, C., Rau, G., 2000. Development of recommendations for SEMG sensors and sensor placement procedures. J. Electromyogr. Kinesiol. 10, 361–374. Hignett, S., 1996. Postural analysis of nursing work. Appl. Ergon. 27, 171–176. Hoe, V., Urquhart, D.M., Kelsall, H.L., Sim, M.R., 2012. Ergonomic design and training for preventing work-related musculoskeletal disorders of the upper limb and neck in adults. Cochrane Database Syst. Rev. 8. Hoogendoorn, W.E., van Poppel, M.N., Bongers, P.M., Koes, B.W., Bouter, L.M., 1999. Physical load during work and leisure time as risk factors for back pain. Scand. J. Work. Environ. Health 387–403. Husain, A., Khan, A., Hasan, F., 2013. Ergonomic evaluation of effects of handle shape and task orientation on human performance in screw driving task. Int. J. Adv. Technol. 4, 105–114. Kadefors, R., Areskoug, A., Dahlman, S., Kilbom, A., Sperling, L., Wikstrom, L., Oster, J., 1993a. An approach to ergonomics evaluation of hand tools. Appl. Ergon. 24, 203–211. Kadefors, R., Wikstrom, L., Oster, J., Dahlman, S., Kilbom, A., Sperling, L., 1993b. Ergonomic evaluation of hand tools: a case study on plate shear. In: Nielson, R., Jorgensen, K. (Eds.), Advances in Industrial Ergonomics and Safety V. Taylor & Francis. Kim, B.B., 2012. Effect of ergonomic design changes in hand tools on physiological cost and subjective ratings. Int. J. Occup. Saf. Ergon. 18, 267–277. Konrad, P., 2005. The abc of emg. In: A practical Introduction to Kinesiological Electromyography, vol. 1. pp. 30–35. Kroemer, K.H., Kroemer, H.J., 1997. Engineering Physiology: Bases of Human Factors/ ergonomics. John Wiley & Sons. Li, K.W., 2002. Ergonomic design and evaluation of wire-tying hand tools. Int. J. Ind. Ergon. 30, 149–161. Magnago, T.S.B.d.S., Lisboa, M.T.L., Griep, R.H., Kirchhof, A.L.C., Guido, L.d.A., 2010. Psychosocial aspects of work and musculoskeletal disorders in nursing workers. Rev. Latino-Am. Enferm. 18, 429–435. Martin, J.L., Norris, B.J., Murphy, E., Crowe, J.A., 2008. Medical device development: the challenge for ergonomics. Appl. Ergon. 39, 271–283.
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Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo
Design and ergonomic assessment of an infusion set connector tool used in nursing work
T
Ehsan Garosia, Adel Mazloumia,b,∗, Reza Kalantaric, Zahra Vahedia, Zahra Shirzhiyand a
Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Iran Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran c Department of Ergonomics, School of Health, Shiraz University of Medical Sciences, Iran d Department of Biomedical Systems & Medical Physics, Tehran University of Medical Sciences, Iran b
A R T I C LE I N FO
A B S T R A C T
Keywords: Ergonomic design Infusion set Nursing
Nursing is a physically demanding job characterized by a high prevalence of fatigue and musculoskeletal disorders. One of the high-exertion and repetitive nursing tasks is the manual connection of an infusion set to a medical fluid bottle. Such physical work can be eased by the design of new hand tools. Correspondingly, this study designed and ergonomically assessed an infusion set connector tool (ISCT) and compared it with that of manual connection. First, a prototype of ISCT was designed to perform infusion set connecting task in the mechanical form. Subsequently, 12 nurses were asked to connect an infusion set to medical bottle in the form of manual and mechanical tasks and these tasks were evaluated using ergonomic indices including muscular activity level, force, posture, and subjective (Borg scale CR10) measures. Results showed that the activity levels (root mean square) of the extensor digitorum communis, flexor carpi radialis, biceps, triceps, and deltoid muscles remarkably decreased when the nurses used the ISCT. The postures of the wrist, arm, and shoulder regions were corrected from Rapid Upper Limb Assessment action level 3 to 2 when the designed tool was used. Additionally, the subjective perception of exertion was significantly lower with the use of the prototype.
1. Introduction Nursing is a physically and psychologically demanding profession with a high prevalence of musculoskeletal disorders (MSDs) as indicated in several studies (Choobineh et al., 2010; Magnago et al., 2010; Menzel, 2007; Smith et al., 2003, 2006). Daraiseh et al., for example, reported that MSDs most frequently occur in the back, neck, and shoulders, followed by the upper back, hands/wrists, and knees/lower legs (Daraiseh et al., 2003). In Iran, the prevalence rates of low back, knee, shoulder, and neck pain were 73.2%, 68.7%, 48.6%, and 46.3%, respectively (Mehrdad et al., 2010). MSDs are also often cited as the reason for sickness-related absences and the high turnover of nurses (Blekesaune and Solem, 2005; Menzel, 2008). Nurses' working conditions usually differ across countries, regions, and hospitals (Simon et al., 2008). These differences are attributed mainly to the provision of instruments and the quality of process management in hospitals. Nurses are involved primarily in the administration of medications in hospital wards and other relevant settings (Raju et al., 1989). As a subset of medication administration,
intravenous (IV) administration is routinely performed by nurses and widely used in hospitals for the transmission of fluids, including blood, drugs, and food in liquid form. The standard infusion equipment for IV administration consists of a bottle or bag containing a medical fluid for dispensation, a plastic administration set, and a suitable needle for insertion into a patient's vein (Flack and Whyte, 1974). Inserting a plastic administration set into a medical fluid container is part of the preparation and administration of IV medication. This task is performed in a manual way by nurses. In intensive care units in particular, the use of maintenance medical fluid is common over one work shift (Bihari et al., 2016), thereby increasing the frequency with which infusion sets are connected. In manual infusion set connecting (ISC) task, nurses usually hold the bottle by one hand and push the infusion set with another hand to make a hole and insert it to the bottle in a specific position. Fig. 1 shows how the task is done by a nurse. In our experience, inserting the infusion set requires a significant gripping force and unnatural flexed and twisted postures of the hand. In the workstation with high height, the shoulder posture is considerable too. Awkward posture and excessive muscular
∗ Corresponding author. School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences, P.O. BOX: 6446, Tehran 14155, I.R, Iran. E-mail address: [email protected] (A. Mazloumi).
https://doi.org/10.1016/j.apergo.2018.09.008 Received 24 November 2017; Received in revised form 12 September 2018; Accepted 12 September 2018 0003-6870/ © 2018 Published by Elsevier Ltd.
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Fig. 1. Manual infusion set connecting task.
improvements to physically demanding tasks in nursing, the aim of this study was to design a new tool and to compare its physical demand and risk to the manual method. It is hypothesized that by designing such ergonomic tool and using it in ISC task, required force and muscle activity will be decreased significantly. Meanwhile, the awkward handarm posture will be improved by using this tool. Indeed, the idea of applying a hand tool for ISC task originated from one of the researchers’ experiences in nursing work. He is a practicing nurse in an Iranian hospital and a researcher focusing on ergonomics in healthcare.
force in manual tasks can be considered risk factors for the development of upper extremity disorders among nurses as they accomplish physical tasks (Li, 2002). Previous researches, including that conducted by (Mital and Kilbom, 1992; Punnett and Wegman, 2004), indicated that the use of arms and hands at an awkward posture and frequent motions of hands/wrists are associated with pain and discomfort. Other studies reported that flexion, extension, and radial and ulnar deviation in the wrist are related to carpal tunnel syndrome (CTS) in many professions (Armstrong and Chaffin, 1979; Tanaka et al., 1995). Moreover, in some studies, exposure to factors involving long duration, force, and awkward postures are known as the main physical risk factor for MSDs development (Gallagher and Heberger, 2013; Hoogendoorn et al., 1999). Improving ergonomic factors, such as the design of tool and equipment, work environments, or both, and training workers in ergonomic principles are expected to reduce the risk of developing MSDs (Hoe et al., 2012) and ease physically demanding nursing tasks. The excellent ergonomic design of medical devices are necessary for guaranteeing safety for both patients and clinical care workers (Martin et al., 2008). Hand tool design/redesign plays an important role in easing the demands of manual work and controlling problems in duties that involve the use of hands and forearms and improves user job satisfaction (Kadefors et al., 1993a; Sperling et al., 1993). Medical tools and devices with ergonomic features also reduce muscle exertion because these instruments decrease the physical demands imposed when people carry out repetitive tasks (Gauthier and Lagacé, 2015; Kim, 2012). Given the necessity of designing new tools for necessary work
2. Methods An experimental study was carried out to evaluate manual and mechanical ISC tasks. In this mean, an infusion set connecting tool (ISCT) was designed and used to perform the mechanical ISC task. 2.1. Design of the ISCT To achieve an ideal design which meets our goals, the idea of developing an ISCT was shared with an industrial design group. As mentioned earlier, among ergonomic risk factors, force is the main problem perceived by nurses during the manual ISC task. To solve this problem and to ensure the functional performance of the tool, the firstclass lever model was used in the primary design. Another concern for manual ISC task was awkward posture in the hand and arm regions. In order to correct this problem, a handle (110 mm, length) in conjunction with a trigger (35°-angle to handle) was attached at the bottom of the main body of the ISCT. (Figs. 2 and 3). 92
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Fig. 2. The sketch of ISCT; A: right view, B: trimetric view.
Fig. 4. Prototype of the ISCT and medical fluid bottle; 1: Infusion set frame, 2: Handle, 3: Trigger, 4: Spring, 5: Infusion set, 6: Medical bottle holder, 7: Medical fluid bottle.
Fig. 3. Three-dimensional view of the ISCT.
2.4. Manual and mechanical ISC tasks
2.2. Prototyping
To connect the infusion set to the medical fluid container, nurses usually hold the container by one hand and insert the infusion set with another hand in a specific position on top of the container. This task requires forceful exertion associated with the gripping and bending of the wrist. Fig. 5 illustrates how the manual ISC task is accomplished. Mechanical ISC task is done by insertion of an infusion set into the medical bottle using ISCT with the following instruction: To use the ISCT first, an infusion set is placed on a specified frame (Fig. 4, item 1), intended for the set. Subsequently, the bottle holder (Fig. 4, item 6) is attached to a medical fluid bottle, and pushing the trigger (Fig. 4, item 3) moves the infusion set forward and enables insertion into the bottle. Detaching the ISCT is easily accomplished by pulling up the device. Fig. 6 illustrates how the mechanical ISC task is executed. A close-up view of manual and mechanical ISC tasks is shown in Fig. 7. The result of a simple task analysis for manual and mechanical ISC tasks was detailed in Table 1.
SolidWorks version 2016 was used to sketch and render the ISCT in three-dimensional form. Figs. 2 and 3 show the sketches and a threedimensional view of the ISCT, respectively. On the basis of the final format of the simulation and the detailed drawing, the prototype of ISCT was made (Fig. 4). Aluminum metal was applied a material to building the prototype. Design dimension is showed in Fig. 3 and the prototype weight is 300 g. This newly developed prototype was registered as a patent in the Iranian Intellectual Property Organization (IIPO), with a registration number of 85545 (Garosi and Kalantari, 2014). Fig. 4 shows a detailed illustration of the ISCT and a medical fluid bottle. 2.3. Final design The prototype form of ISCT was used in all the ergonomic assessments in this work. The final design will be completed considering further formative assessment and summative evaluation of the prototype. 93
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participation in the is study. (Means & SD age: 28 years ± 6.5, weight: 67 kg ± 11.7, stature 1710 mm ± 97). Only right-handed nurses were selected to avoid the influence of hand preference on the survey. All the participants were healthy and did not report any injuries or MSDs. They completed and signed informed consent forms before the initiation of the experiments. 2.6. Procedure A laboratory experiment was set up, and ISC tasks were simulated in a manner similar to how the connection is performed by the nurses in their daily work. An instruction (section 2.4 Mechanical ISC task) was given to the subjects to become familiar with the use of the ISCT and they also participated in a training session and practiced the mechanical ISC task until they were satisfied. Two experimental sessions were set up in one day for each participant. During each session, they were asked to perform the manual or mechanical infusion set connecting task in a randomized order. In order to improve statistical analysis power, the subjects were asked to repeat each of the manual and mechanical tasks 3 times, with a 5-min rest between each session. A same brand of the standard infusion set and a commonly used rectangular medical fluid bottle was used for each trial of the manual and mechanical tasks. As mentioned above, the ISC tasks, simulated in this study was analogous to that conducted in real work conditions. The workstation was adjusted using a base and a wooden platform to provide dimensions similar to those of a real workstation. The height, length and width of the simulated workstation were 95, 60, and 35 cm, respectively, identical to those of an infusion trolley.
Fig. 5. Manual ISC task, worst-case deviation in the upper extremities and trunk body regions.
2.7. Ergonomic assessment of manual and mechanical ISC tasks In this study different ergonomic assessment techniques were used. The subjective assessment was conducted by the Borg scale CR10 (Borg and Kaijser, 2006). Moreover, measures such as electromyography (EMG) and force were applied for objective evaluation under the manual and mechanical tasks. Also, an observational survey based on the Rapid Upper Limb Assessment (RULA) technique (McAtamney and Corlett, 1993) was used for posture assessment in this study. 2.7.1. Subjective assessment Borg scale CR10 was used in the subjective evaluations of perceived exertion. The scale was given to the subjects at the end of each task completion, with the following instructions: “You do not have to specify your feelings, but do select the number that most correctly reflects your perception about physical demands of inserting the infusion set to medical fluid bottle. If you feel no loading, you should answer zero, nothing at all. If you start to feel something just noticeable, your answer is 0.5, extremely weak. If you have an extremely strong impression, your answer will be 10. So, the more you feel, the higher the number you are choosing. Keep in mind that there are no wrong numbers; be honest, do not overestimate or underestimate your ratings” (Borg and Kaijser, 2006; Kroemer and Kroemer, 1997). 2.7.2. EMG assessment A surface bipolar EMG (g-USBamp, made in Austria) was used to measure muscle activity during the manual and mechanical ISC tasks. After appropriate skin preparation, two active Ag/AgCl ring electrodes were attached to the skin using a double-sided tape with a center-tocenter distance of 20 mm. The specific locations of attachment were the participants’ right-side muscles, namely, the extensor digitorum communis (EDC), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), biceps, triceps, and deltoid muscles. Electrode placement was performed in accordance with the protocols of the Surface Electromyography for the Non-Invasive Assessment of Muscles and the ABC of EMG (Hermens et al., 2000; Konrad, 2005). The target muscles were selected using a muscle activation examination during ISC tasks in
Fig. 6. Mechanical ISC task, worst-case deviation in the upper extremities and trunk body regions.
2.5. Participants Twelve nurses (six males and six females) were recruited for 94
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Fig. 7. Close-up view of the manual (A) and mechanical (B) ISC tasks.
measure the force required to insert the infusion set to a medical fluid bottle. In the manual connection mode, the proximal side of the infusion set was fixed onto the probe of the dynamometer for the measurement of the required force. In the mechanical connection mode, the probe of the dynamometer was fixed onto the handle of the ISCT, after which the force required to insert the infusion set to a medical fluid bottle was measured and registered. Force was measured by researchers three times each in the manual and mechanical connection, and the maximum force among the measurements was considered in the evaluation and mean calculation.
a pilot study. The muscle selection for examination was based on some similar preceding studies (Freund et al., 2000; Kadefors et al., 1993b; Yoo, 2013; You et al., 2005). A ground electrode was placed at the distal end of the lateral side of the radial bone. EMG signals were recorded at a sampling rate of 1200 Hz. An online bandpass filter with a cut of frequencies of 0.5 and 500 Hz was applied during signal recording. Before the nurses performed the ISC tasks, the maximum voluntary contractions (MVCs) of the target muscles were performed and the EMG signal of MVC task was recorded for each muscles group, the MVC was done 3 times to enhance statistical power with a 5-min rest between contractions; each contraction took almost 8 s. EMG signal processing: the recorded EMG signals were preprocessed by applying an offline Butterworth bandpass filter with the order of 4 and the cutoff frequencies of 1 and 250 Hz for removing any possible low frequencies artifacts like the baseline offset and wanderings, and high-frequency artifacts. for this purpose, we use fdesign Matlab object for specifying a bandpass filter and use filtfilt Matlab function which applies the specified filter with zero phase shift. For all trials in MVC, manual and mechanical tasks, the EMG activation interval was extracted offline by visual inspection as shown in Fig. 8. After identifying the onset and offset time the RMS of selected part of EMG signal was calculated using Matlab RMS function. Then the mean of RMS values in 3 trials of MVC, are calculated and the mean RMS values in the manual and mechanical task were normalized to mean RMS value derived from MVC task in target muscles. The described procedures for signal processing were done in the build-in functions in MATLAB R2014a software.
2.7.4. Posture evaluation using RULA Ergonomic risk factors were assessed during the manual and mechanical ISC tasks through direct observation based on RULA (McAtamney and Corlett, 1993). The simulated manual ISC task for posture evaluation is similar to the actual task performed in a hospital, as stated in the “task selection.” The main criteria for posture selection in the manual and mechanical connection were the worst cases (maximum range of motion) in viewpoint of maximum flexion, deviation and rotation of the hand and wrist areas during the assessment of posture as the nurses completed the manual ISC task. Posture assessment was carried out by the examiners, as ergonomic specialists and the worst cases were determined through direct observation of the postural deviations during tasks implementation. 2.8. Statistical analyses Before data analyzing, Kolmogorov–Smirnov test was used to determine data distribution normality. Wilcoxon signed-rank test was done to compare muscle activity level and subjective Borg scale data for the manual and mechanical ISC tasks. A p-value of less than 0.05 was
2.7.3. Required force measurement A portable dynamometer model (Mecmesin, basic force gauge, high accuracy ± 0.25%, sample rate 1000 Hz, made in USA) was used to Table 1 Manual and mechanical ISC subtasks. Subtasks in manual connection 1) 2) 3) 4)
Unpacking the infusion set Removing the cover (cab) of the infusion set Putting the medical fluid bottle on the station Taking and holding the infusion set using the dominant hand and the medical fluid bottle using the other hand 5) Inserting the infusion set to the medical fluid bottle by pushing it along the vertical axis 6) Releasing the hand from the Infusion set
Subtasks in mechanical connection 1) 2) 3) 4)
Unpacking the infusion set Removing the cover (cab) of the infusion set Putting the medical fluid bottle on the station Taking and holding the infusion set and placing it in the ISCT using the dominant hand and the medical fluid bottle using the other hand 5) Attaching the tool to the medical fluid bottle and pushing the handle of the tool to enable infusion set insertion into the bottle 6) Releasing the ISCT from the medical fluid bottle
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Fig. 8. The EMG activation of the Flexor Carpi Radialis (FCR) muscle, obtained from participant number six.
considered statistically significant.
Table 3 Results of Wilcoxon signed-rank test on EMG (%MVC).
3. Results The results showed significant differences between the objective and subjective measurement variables. The overall results of the subjective assessment indicated that the degree of perceived exertion significantly differed (p = 0.002), as indicated by the mean values derived from the Borg scale for ISCT-assisted connection, 2.3 ( ± 0.49), and manual connection, 5 ( ± 1.20). The Borg scale data for the 12 participants are summarized in Table 2. The results related to muscular strain measured by surface EMG (% MVC) in the manual and mechanical modes are presented in Table 3. The Kolmogorov–Smirnov test showed that the distribution of EMG signals and data was non-normal. Therefore, the Wilcoxon signed-rank test was carried out to compare muscle activity level, Borg scale data, and force in the manual and mechanical ISC. The muscle activity of each muscle group decreased in the mechanical ISC, and the most strongly activated muscles in both the manual and mechanical connection were the EDC and FCU. The Wilcoxon test also revealed significant differences in the muscular activity of the EDC, FCR, biceps, triceps, and deltoid muscles between the two ISC methods. Muscular activity was significantly higher during the manual ISC. Regarding the maximum amount of force to do the tasks, the armhand force to insert the infusion set to the bottle was (mean ± SD): 112.16 ± 5.62 N, in the manual ISC task. In the mechanical task, the amount of hand grip force to insert the infusion set into the bottle was measured (mean ± SD): 49.16 ± 6.82 N, using ISCT. The findings on posture assessment during ISC tasks are presented in Table 4. The median value of the final RULA score for the right side of the body during the manual connection was 6, whereas the median value for the same side of the body during the mechanical connection was 3. The action level with respect to the manual connection was 3, which changed to 2 during the mechanical connection. The action level on the left side of the body was the same under both the connection
Mean score
SD
p value
Manual connection Mechanical connection
5 2.33
1.20 0.49
0.002
Manual connection Mean ± SD
Mechanical connection Mean ± SD
p value
Extensor Digitorum Communis Flexor Carpi Radialis Flexor Carpi Ulnaris Biceps Triceps Deltoids
59.44 ± 14.97
36.28 ± 9.71
0.002
44.2 47.5 37.1 55.3 31.6
25.1 ± 11.25 38.03 ± 19.13 15.90 ± 11.60 27.23 ± 17.97 14.55 ± 10.85
0.003 0.08 0.003 0.005 0.003
± ± ± ± ±
21.59 18.02 26.68 16.66 16.99
methods.
4. Discussion The main aim of this study was to determine the ergonomic advantages of a newly developed ISCT over the manual connection of infusion sets. This tool was designed based on the ergonomic principles and assumption of force and posture correction in hands and arms. The data analyses reflected ergonomic improvements in force, posture, and personal perception when the ISCT was used to connect infusion sets to medical fluid bottles. The subjective evaluation showed a significant easing of the ISC task when the developed ISCT was used by the nurses. No similar or relevant studies have been conducted with respect to the subjective assessment of manual ISC. As indicated in previous studies, manual tasks require more physical exertion and may lead to target muscle fatigue and increase heart rate (Borg, 1985; Ulin et al., 1993). This issue may be the reasons why the participants’ subjective perception of exertion was higher during the manual connection than during the mechanical task completion. Another important difference was in the muscle activity level. The surface EMG recording in the current work showed that all the six target muscles were active during the mechanical and manual connection tasks but that the EDC and FCU muscles were the strongest activated muscles in the manual and mechanical connection, respectively. EMG has been identified as a major quantitative measure for studying cumulative trauma disorder (Li, 2002) and a technique for evaluating and recording the electrical activity produced by skeletal muscles (Husain et al., 2013). The findings in the current study are
Table 2 Borg scale results on manual and mechanical ISC (N = 12). Task
Muscle
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Table 4 Results of posture evaluation for each side of the body during manual and mechanical ISC. Tasks
Body side
Score A
Score B
Score C
Score D
Final score
Action level
Manual connection
Right Left Right Left
5 2 3 2
2 2 2 2
8 2 4 2
3 3 3 3
6 3 3 3
3 2 2 2
Mechanical connection
Score A: Posture of arm and wrist; Score B: Posture of neck, trunk, and leg; Score C: Force and frequency in A region; Score D: Force and frequency in B regions; Final score: The final score is calculated based on table C in RULA score sheet; Action level 1: acceptable posture; Action level 2: Further investigation is needed, and changes may be required; Action level 3: Investigation and changes are required soon; Action level 4: Investigation and changes are required immediately.
required to complete the mechanical connection was 0.86 s longer than the time to complete the manual connection. Although this variable was not reported and considered as the main objective in this study, it can be interpreted that such kind of trade-off should be regarded in the selection and applying any hand tools like ISCT. The little longer time here may be shortened by training sessions. According to Oulasvirta study “the inferior performance of the novices must be accounted for their lack of device-specific experience (Oulasvirta et al., 2011).
attributed to the anatomical muscular function executed in each task (Ghosh, 2007). The Wilcoxon analysis showed a significant difference in muscular activity between the two ISC methods. The muscular activity (%MVC) of all the target muscles, except FCU, which was lower with the use of the ISCT than with the manual connection. Although the difference in FCU muscle activation was not statistically significant, an important issue for consideration is that such variance may be due to the lower muscle activity of two participants in the manual connection than in the mechanical connection. This effect may be related to the mismatch between the ISCT handle and the participants’ anthropometric dimensions. The findings are in line with those of previous studies that reported significant differences in hand muscle activity after the design and redesign of a new hand tool (Li, 2002; Sancibrian et al., 2014). Regarding the force measured for inserting the infusion set to the bottle, the subjects were compelled to apply a force greater than 100 N to accomplish the manual connection. This force was significantly decreased by 49.16 N through use of the ISCT. A reduction of more than fifty percent in the required force is remarkable in this case. This level of force is less than 10 percent of maximum grip strength of dominant hand in the Iranian men aged 20–24 years and women aged 35–39 years (Mohammadian et al., 2014). The body postures of the nurses were evaluated via RULA. The RULA scores for the participants’ arm/wrist (score A) and neck/trunk/ legs (score B), as well as their final scores, were high as they performed the manual ISC (Table 4). During the manual connection, the upper and lower right arm of the participants were in an awkward and abducted posture. The right wrist was flexed with a twisted posture, and the left hand, which is used to hold a medical fluid bottle was in a natural posture in both the manual and mechanical connection tasks. In the mechanical connection, the posture of the right arm and wrist improved, and the action level changed from 3 in the manual task to 2 in the mechanical tasks. Hignet demonstrated that working with hospital equipment requires harmful postures for more than 50% of the time (Hignett, 1996). As reflected in the posture evaluation in the present study, the manual ISC was carried out with poor posture. This problem requires further investigation and addressing in the near future to prevent injuries. In this research, changing from manual connection to mechanical task completion corrected posture. Note, however, that posture correction using the ISCT was observed in a single work context with a fixed workstation height of 85 cm (the same as the standard trolley height). In cases wherein the heights of trolleys differ, the posture of users may also vary, and the effects of the ISCT may change. Therefore, trolley height should be ergonomically adjusted before work is carried out on it. Nevertheless, with the final anthropometric design of the novel ISCT, along with the provision of training and guidelines, improvement in posture and ease of use are expected. Moreover, the ISCT can work with other types of infusion sets and bottles and can be universally useful for a variety of sets/bottles by changing the medical bottle holder (Fig. 4, part 6) into an adjustable version. What is more, a small difference of less than 1 s was found between the two connections methods in terms of the time required to complete the tasks. Despite the fact that ISCT could improve the infusion task from the viewpoints of required force and body posture, the time
5. Conclusion Considering that the manual connection of infusion sets is not an ergonomic task for nurses working in hospitals, a necessary requirement is to improve task completion by introducing a new ergonomic hand tool. Accordingly, this study developed a patent-pending ISCT and evaluated the tool from different ergonomic viewpoints. The ISCT could significantly reduce the force and muscle activity during performing ISC task and improved body posture. In general, ergonomic interventions, such the design of new tools, are a practical approach to controlling musculoskeletal risk factors and providing a safe and healthy workplace for nurses. 6. Limitations of the study The current study had some limitations. First, all the ergonomic assessments were conducted using a prototype form of the ISCT. Using an optimized and final ISCT design would provide summative results and enhance ease of use among nurses. Second, one type of medical fluid bottle was used in the ISC tasks. Hence, the physical demands for infusion set connection task may vary because of differences in the quality, shape, and material of medical fluid containers. Working with other types of bottles would be helpful in informative assessment of the ISCT. Lastly, they were likely some investigators biases due to unsynchronized and manual methods of data collection and analyses. Acknowledgments This article was developed under the framework of Project Noe30454, at Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences and Health Services. The authors thank all participants for their kind corporation in this study and also Mr. Mojtaba Ahmadi for the 3D design. References Armstrong, T.J., Chaffin, D., 1979. Carpal tunnel syndrome and selected personal attributes. J. Occup. Environ. Med. 21, 481–486. Bihari, S., Watts, N.R., Seppelt, I., Thompson, K., Myburgh, A., Prakash, S., Bersten, A., 2016. Maintenance fluid practices in intensive care units in Australia and New Zealand. Crit. Care Resuscitation 18, 89. Blekesaune, M., Solem, P.E., 2005. Working conditions and early retirement a prospective study of retirement behavior. Res. Aging 27, 3–30. Borg, E., Kaijser, L., 2006. A comparison between three rating scales for perceived exertion and two different work tests. Scand. J. Med. Sci. Sports 16, 57–69. Borg, G., 1985. An Introduction to Borg's RPE-scale. Movement Publications, Ithaca. Choobineh, A., Movahed, M., Tabatabaie, S.H., Kumashiro, M., 2010. Perceived demands
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