Development of a device for measuring tidal volume ambulatorily withouto calibration using optical fibers

点击翻译按钮获取中文摘要

Although a flowmeter gives accurate tidal volume, it requires a facemask which makes a subject uncomfortable and even affects breathing pattern in the subject. Measurements using any methods other than the flowmeter must be calibrated by the flowmeter in each subject. To dispense with the facemask and calibration, we developed a new method which measures the change in the body trunk volume, because it is established that the change in the body trunk is equal to that in the lung volume.A curvature sensor using an optical fiber was developed to yield a cross-sectional area of the body trunk. The shapes of two cross sections were reconstructed from 20 curvature sensors, to produce the area. Other two cross-sectional areas were estimated based on the relation between an area and a circumference length. The four cross-sectional areas and the three distances between them gave the body trunk volume related to respiration. Circumference lengths and distances were measured by length sensors which we also developed using optical fibers.The change in the lung volume was measured by a hot-wire flowmeter in six subjects, and the change in the body trunk was simultaneously measured by our method. The relation between two measured change was linear without much scattering, and the slope of the regression line between them ranged from 0.8 to 1.2.