Arterial Simulator with Configurable Pulse Wave Velocity for Quantitative Tracheal Endoscopic Image Measurement

In quantitative diagnosis of tracheomalacia using endoscopic examination, it is necessary to perform spatiotem- poral quantification of cardiogenic oscillations on the tracheal wall that interfere with the measurement of respiratory fluctua- tions. Measurement accuracy and characteristics by high-speed endoscopic imaging are unclear against cardiogenic oscillations observed in tracheal endoscopic images, which are considered to include arterial pulse waves. To understand the mechanism of such cardiogenic oscillations, it is also necessary to distinguish between arterial pulse waves and cardiac tissue motion. In this paper, we propose an arterial pulse wave simulator consisting of a pulsatile pump and an ultra-flexible tube. Pulse transit time is measured by laser displacement sensors placed at two points on the tube deformed by the pulse wave. By adjusting the pressure of the liquid inside the tube, it is possible to generate specific pulse wave velocities within a certain range. Using the adjusted pulse wave velocity as a reference value, we quantitatively evaluate the measurement accuracy of pulse waves obtained by high-speed endoscopic imaging. We have experimentally evaluated the quality of pulse wave velocity adjustment of the developed simulator and demonstrated the estimation of pulse wave velocity by endoscopic texture tracking.