A close relationship exists between lesions in the peripheral circulation and angiopathy in the central organs. For the diagnosis of angiopathy, quantitative methods based on the pulse wave transit time, etc., can be used. For lesions in the peripheral circulation, however, few established diagnostic methods exist. According to the Windkessel model, noninvasive measurements can be performed using the radial arterial pressure waveform (RAPW) as the input signal and fingertip photoplethysmography (PPG), which detects changed in the peripheral blood volume, as the output signal. A fast Fourier transform (FFT) is conducted on both the waveforms. By comparing the amplitudes of the measured frequency components, a time constant is then calculated from the frequency transfer characteristics that are thus obtained. Assuming that this time constant can be used as a quantitative index of peripheral circulation, the present study sought to prove the effectiveness in this diagnosis method of angiopathy.

The novel noninvasive method to diagnose microvascular lesions has been developed using time constants obtained from a radial artery pulse (RAPW) and photoplethysmogram (PPG) utilizing the Windkessel model. There are two methods for measuring RAPW : The first is reflectance photoelectric and the second is air conduction. The purpose of this study is to investigate which method was better. Time constants were calculated from each frequency component, with fixtures attached to the palm and forearm. Pressure applied to the RAPW sensor was varied 6 points. Furthermore, the time constant calculability rate and variation rate calculated when the optical and air conduction sensor were used. The maximum value of the calculability rate for the former and latter were 88% and 100%, respectively. The minimum value of variability of the time constant was 18% and 11% for the former and latter, respectively. The results demonstrate that air conduction was the superior method.

　吸引は分泌物、異物を自力で排出できない患者に対して気道の閉塞や分泌物貯留による肺炎など感染症を防ぐ目的で実施される看護技術である。しかし、目視できない人体内部に対してカテーテルを挿入するという感覚的で細かな手指巧緻動作を言語化して伝えることが非常に難しく、看護教育上の課題の一つであるといえる。

　そこで本研究では、高精度のモーショントラッキングが可能な磁気式の3次元位置姿勢計測システム（Polhemus社、Viper）を用いた吸引手技計測システムを提案した。カテーテルの先端部、中央部および手指にレシーバを装着して取得した位置姿勢データをMATLAB（MathWorks社）で座標変換および可視化することで、システムの妥当性を検証した。その結果、吸引手技における実施者の巧緻な手指の動き、手首の前背屈ならびに吸引カテーテルの進入度を計測・可視化できた。今後は本システムを用いて、吸引手技におけるカテーテル進入時の手指巧緻動作の解析を進めていく。

In recent years, augmented reality (AR) has been used in fields such as work support. Because AR overlaps the real environment with a virtual environment, the visibility of the real and virtual environments may deteriorate depending on the manner in which the virtual environment is displayed. Therefore, research has been conducted on view management to maintain and manage the visibility of the composite result of the real and virtual environments, and methods to appropriately position virtual objects in relation to the real environment have been proposed. However, the combination of the background color of the real environment and the color of the virtual object may result in low visibility, even when the object is displayed at the appropriate position. In this study, we investigated the effects of color schemes on the visibility of the annotation user interface (UI), aiming to clarify the color schemes with high visibility against the background color. Paired comparison revealed a positive correlation between visibility and differences in brightness and color for many background colors. Based on this result and the World Wide Web Consortium/Web Accessibility Initiative (W3C/WAI) findings that the visibility of color schemes with a brightness difference of 125 or more between the background color (the UI color in the experiment) and the text color and a color difference of 500 or more is high, a positive correlation was noted for many background colors. Therefore, we considered that the visibility could be improved by setting the UI color with the largest difference in brightness and color between the background color and the text color and setting the text color with the largest difference in brightness and color between the UI color and the text color. The results of an experiment to evaluate the proposed method showed that the visibility scores for the conditions set by the proposed method were significantly higher, and no significant difference was observed in eye fatigue, suggesting that the proposed method might improve visibility without having a negative effect on eye fatigue.

A novel diagnostic method has been developed for microvascular lesions using time constants obtained from the peripheral Windkessel model (WK model). Since the time constant of the WK model reflects changes in resistance and vascular elasticity due to a decrease in the internal vessel diameter, an increase in surface roughness of intima, and an increase in blood viscosity, it was proposed to use it as an indicator for vascular evaluation. For noninvasive and easy measurement of the time constant, it is necessary to calculate from the frequency components of the arterial pressure pulse and phalangeal volume pulse. Therefore, it is necessary to establish each pulse wave measurement method and to consider the optimal combination. The fingertip photoplethysmograph was used because it is said to be proportional to the volume pulse of the fingertip. Owing to the difficulty of using the conventional air-conduction method for measuring the arterial pressure pulse, reflection photo and cuff pressure methods were considered. The probability of obtaining time constants and the fluctuation rate were compared across the three methods. The results demonstrated the superiority of the air-conduction method over the other two. The air-conduction method was considered to produce a waveform proportional to the arterial blood pressure pulse wave. The best pulse wave measurement method for measuring peripheral time constants were the air-conduction method for arterial pressure pulse and the transmission photo method for fingertip volume pulse.

We assessed the effects of augmented reality (AR) on learning. We developed an AR manual installed on smart glass and compared it with the conventional paper manual. Forty-nine students in clinical engineering, without experience in hemodialysis priming were randomly recruited to prime hemodialysis units using either a conventional manual (CM; n = 28; male, n = 15) or the AR manual (n = 18; male, n = 7). We measured the amount of the time required to complete the task, accuracy (number of failed processes/number of total processes), and the ratio of persons who did not complete the task. The results were compared between the CM group (CMG) and the AR group (ARG) at baseline and after two and four weeks, and the abilities of both groups to perform the task without a manual were compared three months later. The time in the ARG shortened faster. Accuracy in the ARG was initially inferior, but improved each time, eventually, it was superior to the CMG. The ratio of ARG was superior, but when the tasks were done without the manual, the CMG was superior. These results suggested that AR may be effective for learning medical technologies.