Measurement of Body Density by Means of He Replacement Method

Research Project

Project/Area Number	07557035
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	展開研究
Research Field	Hygiene
Research Institution	Nihon University
Principal Investigator	YAJIMA Kazuyoshi (1997) Nihon University, School of Medicine, Professor, 医学部, 教授 (40010029) 伊藤雅夫 (1995-1996) 日本大学, 医学部, 助教授 (40059887)
Co-Investigator(Kenkyū-buntansha)	WATANABE Naotaka Nihon University, College of Engineering, Associate Professor, 工学部, 助教授 (20120595) ITO Masao Tokyo University of agriculture, Faculty of Bioindustry, Professor, 生物産業学部, 教授 (40059887) 丸瑠璃子日本大学, 医学部, 講師 (20059091) 谷島一嘉日本大学, 医学部, 教授 (40010029)
Project Period (FY)	1995 – 1997
Project Status	Completed (Fiscal Year 1997)
Budget Amount *help	¥13,900,000 (Direct Cost: ¥13,900,000) Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000) Fiscal Year 1996: ¥6,000,000 (Direct Cost: ¥6,000,000) Fiscal Year 1995: ¥6,700,000 (Direct Cost: ¥6,700,000)
Keywords	Body Density / He gas Replacement Method / Body Composition / % Fat / 人体体積計 / ヘリウムガス置換方式 / 体密度 / 体脂肪 / 肥満判定 / 肥満測定
Research Abstract	To obtain body density, highly precise measurement of body volume and body weight is essential. Conventionally body volume has been measured by immersing the subject completely in the water. Yet to ensure an extreme precision by this method, complicated calculations are necessary to obtain the gas amount remaining in the lungs. We have relied on the measurement by air replacement for this purpose, but the pressurization during the process has caused substantial discomfort to the subject, and effective method for measuring body volume. Having devised an apparatus to measure body volume by replacing it with diluted helium without pressurization, we examined the parameters affecting the measurement precision and evaluated the device's scientific aptitude in comparison with the water-immersion method. To obtain a more accurate value of body volume the capacity of the apparatus should be minimized as far as equal distribution of He gas is ensured. Another condition is that the measurement sho … More uld be made in the area of a high He concentration. A 1 liter change in body volume results in a change in the He concentration of 0.01% in an apparatus of 1000 liter and 0.005% in that of 2000 liter. As 0.05% is the measurable limit for our trial production, the He concentration at the measurement point should be 20% to yield a precision of 0.01% in an apparatus of 1000 liter capacity. The measurement conditions were : the apparatus capacity is 850.508 liter ; He-gas introduction rate is 25 l/min ; He-gas volume introduced were 100-120 liter (final He concentration were 10-15%). The increase in the atmospheric pressure from the He-gas introduction ranged between 0.12-0.15 mmHg. It was crucial to maintain airtightness. In an experiment with a water bag of known volume, the correlation coefficient for the values measured by this method was estimated at 0.994. When the measurements on 15 subjects were compared between this and the He replacement method, the correlation coefficient stood at 0.89. Less