Introduction
The ergonomics has been considered important in practicing surgical laparoscopy, and prior studies have shown significance of relevant factors e.g. operating room setup and design of surgical devices. However, little has been known in flexible endoscopy; How do endoscopists control flexible endoscopes? Which muscles are loaded during endoscopy? The deeper understanding of ergonomic aspects in flexible endoscopy is indispensable, since the number of endoscopies performed and its complexity are rapidly increasing.
Aims & Methods
We aimed to identify the differences of ergonomics between diagnostic endoscopy (EGD) and therapeutic endoscopy (ESD), by 1) multiple motion capture technology, and 2) wireless surface electromyography (EMG), in pre-clinical setting.
1) The multiple motion capture assessment
The control section of standard flexible endoscope (GIF-Q260J; Olympus, Tokyo, Japan), from the boot to the angulation knobs, was marked with 6 optical reflective markers. These markers were traced using a motion capture system (OptiTrack Flex13; NaturalPoint, OR) and the data were processed to generate 3-D coordinate data (The sternum manubrium of the endoscopist was setup as the coordinate origin; X: left-right axis, Y: cranio-caudal axis, Z: antero-posterior axis). EGD and ESD were performed with this motion capture system using live porcine models. For each endoscopist, mean±2SD for plotted coordinates from the origin was calculated in the three axes and described as a range of his/her arm/hand movement. The data were compared between EGD and ESD.
2) EMG assessment
Muscle activation of the left biceps brachii muscle, trapezius muscle, extensor carpi ulnaris muscle, flexor carpi radialis muscle, pronator teres muscle, thenar muscle, back neck muscle, and erector spinae muscle were recorded during endoscopic procedures using wireless surface EMG (BioLog DL-5500, DL-510A; S&ME, Tokyo, Japan). The maximal voluntary contraction (MVC) was obtained to normalize root-mean-square muscle activation as %MVC. We compared differences in muscle activity between EGD and ESD using %MVC.
Results
1) The motion capture was performed on 15 board-certified endoscopists conducting EGD (n=13) and ESD (n=12). The movement range of endoscopist’s left hand/arm holding endoscope is shown in the Table. On all three axes, the range of movement was significantly narrower during ESD than during EGD (X, p<0.001; Y, p=0.015; Z, p<0.001).
| EGD | ESD |
| X axis | Y axis | Z axis | X axis | Y axis | Z axis |
| Mean ± 2SD (cm) | -0.32±14.2
| -24.3±11.0
| 12.8±11.6
| -1.3±9.9
| -22.8±9.8
| 7.9±8.9
|
2) The EMG was recorded during 15 EGDs and 8 ESDs. The %MVC was higher during ESD than EGD in an analysis including all muscles (LS-mean±SE; EGD, 28.9±1.5%; ESD, 34.1±2.6%; p=0.078). The comparison by each specific muscle showed that the extensor carpi ulnaris muscle (EGD, 34.6±3.5%; ESD, 47.8±5.8%; p=0.093) and the pronator teres muscle (EGD, 42.8±6.6%; ESD, 67.6±10.9%; p=0.092) had significantly larger %MVC during ESD (p<0.1 was considered statistically significant).
Conclusion
Our study has first shown that the range of endoscopis’s movement was significantly narrower in therapeutic endoscopy than in diagnostic endoscopy. Furthermore, it was demonstrated that muscle activity, especially in left forearm muscles, was larger during therapeutic endoscopy. These data may help understanding the ergonomics in flexible endoscopy, and potentially contribute to optimize its working environment and further development of relevant medical devices.
