For developing medical devices with high usability, it is important to understand and specify the context of use through usability testing. In this study, we have evaluated the effectiveness of think-aloud protocol and impact analysis as usability testing methods for healthcare professionals. An endotracheal tube cuff inflator was used for usability testing. First, five nurses were required to perform a cuff pressure management task using the current equipment. Besides, the think-aloud protocol and video-recording were used during the task to investigate usability problems of the current equipment. Next, the usability problems were classified into the order to be resolved by impact analysis. Then, a development equipment was prototyped and designed. Finally, ten nurses were required to perform the cuff pressure management task using the current equipment and the development equipment. As a result, the time required for the task in the case of the development equipment was shorter than that in case of current equipment. Furthermore, the subjective evaluation in the case of prototype equipment was higher than that in the case of development equipment. These data suggested that the usability of the development equipment was higher than that of the current equipment. From the above, it was considered that the combination of the think-aloud protocol and the impact analysis was effective for usability improvement of medical devices.

Assisting with post-defecation cleansing is said to cause psychological stress in both caregivers and care recipients. In the clinical setting, many patients with hemiplegia wish to acquire cleansing movements that involve approaching the perianal region from the back, but some find it difficult. Thus, this study aimed to elucidate the movement strategies for accomplishing these cleansing movements in patients with hemiplegia. Cleansing movements were measured using a 3D motion analysis device in 6 healthy individuals and 8 patients with hemiplegia, and results were compared between healthy individuals and patients with hemiplegia and between patients with hemiplegia with different motor function. Healthy individuals and patients with hemiplegia who could elevate the pelvis on the toilet seat performed the cleansing movements while elevating the pelvis at ＞10° and shifting the center of pressure of the buttocks forward. On the other hand, those who could not elevate the pelvis performed the cleansing movements while pushing off the floor with the leg on the unaffected side to shift the buttocks backward to the paralyzed side, and laterally flexing the thorax. Taken together, the function enabling the pelvic elevation at ＞10° and that enabling a posterior shift of the center of pressure of the buttocks on the toilet seat were shown to be important strategies for smoothly performing post-defecation cleansing movements that involve approaching the perianal region from the back.

In this study, to clarify the situations causing mental workloads that make nursing practice difficult for young nurses in their daily work at university hospital, free-form answers from 293 nurses who are in the 2nd or 3rd year of experience were analyzed using text mining. As a result, 78 codes and 30 categories were extracted and classified into situations causing mental stress, environmental factors, personal factors, and situations causing mental strains. Situations causing mental stress included ‘Situations that multi-task have occurred’ and ‘Situations that nurses are involved in a scene between life and death of a patient’, etc., environmental factors included ‘Situations that nurses work in the night shift’, etc., and personal factors included ‘Situations that nurses lack of knowledge /skills /experiences’, etc. Situations causing mental strains, which were influenced by the situations causing mental stress, environmental factors, and personal factors, included ‘Situations that observational abilities of nurses decreased’, etc.

In this study, we quantify the center of pressure （COP） trajectory oscillation as the difference between the measured COP trajectory and approximate curve during walking. Further, we determine the relationship between the COP trajectory oscillation and center of gravity oscillation of each body part during walking to examine its effectiveness as an index of walking. The subjects were 10 young males who walked at free speed along a 10-m walking path. We measured the COP position and displacement of 22 markers in the whole body in the left-right direction during walking and calculated the amount of oscillation of the center of foot pressure trajectory and the center of mass of 14 segments. The results showed that the amount of oscillation of COP trajectory substantially differed among walking periods; it was larger during heel-ground contact and landing, which were considered unstable during walking. In addition, it was related to the center of mass oscillation among the right forearm, right upper arm, left upper arm, head, and torso parts. These results indicate that COP trajectory oscillation can be an index to evaluate the sway and posture control of each body part.

This study examined effects of cooling blunting by plantar cooling on postural control by reproducing the center of pressure （COP） position within the range of voluntary movement control. The participants in the study included 18 healthy young male subjects （21.6±1.6 y）. The COP position was displayed in real time on a floor reaction force gauge, and the subject was asked to memorize the forward tilt （65％ of foot length） and backward tilt （30％ of foot length） positions. The COP position was measured by reproducing the memorized COP position and subsequently cooling the plantar area with ice water to reproduce the COP position again. Results found that the absolute COP positional error increased significantly in forward tilt and tended to increase in backward tilt. This increase in absolute COP positional repeatability error and COP sway might be because of decreased pressure information from plantar mechanoreceptors owing to cooling blunting of the sole. Study results suggest that a decrease in plantar pressure information owing to cooling of the plantar area affects the COP position’s reproducibility.