Assessing the Ergonomic Design of a New Back Table for Perioperative Nurses
TimeThursday, April 152:00pm - 3:00pm EDT
LocationEducation and Simulation
DescriptionThe statement ‘Health affects a person’s working life and working conditions affect a worker’s health’ shows a correlation between a person’s health and workplace design . Like industry, workers (surgeons, perioperative and assistant nurses) in the Operating Room (OR) are subjected to ergonomic risk factors which negatively affects the health. Healthcare sector is one of the most affected occupational sector by musculoskeletal disorders, with nursing as the most physically demanding occupation . Perioperative/Scrub nurses are registered nurses tasked with necessary arrangement and preparation of the OR environment throughout (prior, during and after) the surgery. Nurses may require to lift up to 20 trays of instruments with each tray weighing about 18-25 lbs during their daily work-routine and are exposed to risk of injury due to overexertion . A back table (TabA) consists of a single working surface and is used by Scrub nurses to perform their duties. However, the stacked formation of the trays in this design impels frequent manual maneuver (i.e., lifting) of trays, causing an influence on the ergonomics of the perioperative nurse. Considering this hindrance, a new design (TabB) was developed with an additional provision of 3 different working levels, each located at different heights one above the other (decks). Besides having height adjustability, the table also provides ample of space for each instrument tray to be placed separately without stacking them on top of each other. Although the new design shows promising improvement in the performance and safety of the nurses, a thorough assessment is needed for validating the effectiveness of TabB. Thus, our group has developed a platform to conduct a laboratory evaluation for comparing the design features of the two tables (TabA, TabB) and their biomechanical consequences on nurses.
In this study, we will be demonstrating our plan for comparing the two designs, which includes a biomechanical assessment using 12 participants (6M, 6F). A 2x3x2x2 design will be implemented wherein four independent factors: table design (TabA, TabB), table height (Low, Medium, High), gender (Male, Female) and professionalism (expert, novice) will be considered. Responses include subjective (ratings of perceived exertion - Borg’s CR- 10, cognitive and physical demand - NASA-TLX) and objective measures (Postural assessment – REBA, Maximum low back and shoulder loads) associated with performing a lifting task on both tables. The experimental session will be divided into two parts. First part will include lifting of 4 trays weighing 15- 22 lbs. from instrument tray table one at a time, holding it for 15 seconds at waist height and then placing it on the corresponding number marked on the tables (guided by an automated voice speech timer). This will be repeated 5 times for each table and the total duration for performing the lifting task on each table will be ~20 minutes. Ratings of perceived exertion for forearms, shoulder, neck, Low-back and legs will be collected using BORG CR-10 scale. Simultaneously, inertial measurement unit (Xsens®, 60 Hz), and force plates (AMTI, 1000 Hz) will be used to collect motion and external force data while the participant performs lifting. We have developed a simplified model of inverse dynamics through which peak shoulder and back loads will be estimated. The second task will involve finding an instrument amongst the set of four instrument trays positioned on the respective tables in respective stacking configurations. A stopwatch will be used to measure and record the time taken by the participant to remove the instrument. Finally, the participants will be asked to rate their cognitive and physical loads using the NASA-TLX scale.
A preliminary experiment was performed by implementing the designed protocol and using a single participant (Male, Height: 5’10”, Weight: 166 lbs.). Results show that the maximum shoulder moment (averaged for 5 trials) was higher for TabA (48.2 N-m) compared to TabB (42.7 N-m). On the contrary, resultant moment at low back was higher for TabB (70.6 N-m) compared to TabA (59.6 N-m). Further, NASA-TLX results showed higher mental demand (25 vs 15), physical demand (55 vs. 25), and more effort (55 vs. 25) for TabA than TabB. However, the duration of the lifting task on TabB was lesser than TabA (mean time per trial were 5 and 1.17 sec for TabA and TabB respectively). The participant struggled to accomplish the tasks performed on TabA due to repetitive lifting of the instrument trays and resulted in increased frustration (measured by NASA TLX), as compared to TabB. REBA assessment indicated scores of 8.8 and 9 for TabA and TabB respectively. The efficiency of TabB in finding instruments was ~76% higher than TabA. Subjective questionnaire showed that TabB improved visibility and accessibility of instruments.
Our preliminary findings show that TabB performed slightly better than TabA. Although the abovementioned results were obtained from a single participant, the plan includes a total of 16 participants (8 male, 8 female) and our current efforts include data collection and analysis. During our presentation, we will be considering more participants and results will be presented in further depth including statistical analysis of the designed experiment. Through this study, we plan to conduct an ergonomic assessment on the instrument tables and suggest suitable design improvements for reducing risk of injuries and enhance performance of perioperative nurse. The outcomes will demonstrate a quantitative comparison of performance and risk of fatigue/injury between the two tables. It is expected that new design will help lower the muscle fatigue in low-back/shoulder by reducing the frequency of lifting exertions. Meanwhile, it is hypothesized that the new table would provide a better accessibility and visibility of surgical instruments that may help to improve the nurses’ performance and reduce the musculoskeletal discomfort during the surgery. Our preliminary results support the hypothesis, and our future work will include a complete assessment using 12 participants to obtain robust results. The feedback provided by the participants will be utilized in the design improvement process.
 F. Vural and E. Sutsunbuloglu, “Ergonomics: an important factor in the operating room,” in Journal of Perioperative Practice, 2016, vol. 26, no. 7–8, pp. 174–178.
 M. Clari et al., “Upper limb work-related musculoskeletal disorders in operating room nurses: A multicenter cross-sectional study,” Int. J. Environ. Res. Public Health, vol. 16, no. 16, 2019.
 A. Sheikhzadeh, C. Gore, J. D. Zuckerman, and M. Nordin, “Perioperating nurses and technicians’ perceptions of ergonomic risk factors in the surgical environment,” Appl. Ergon., vol. 40, no. 5, pp. 833–839, 2009.