浮腫評価のための体肢容積計の開発

周産期医学にとって浮腫の定量評価は重要である｡これまでは,測定部位の2箇所の周囲長をメジャーで測り,その変化により浮腫を評価している｡また周囲長により容積を推定する方法も提案されている｡しかしながら,この方法ではメジャーの測定部位への巻き付け方による誤差や容積を推定する根拠となる測定部位のモデル形状と実際の測定部位の形状との誤差など様々な誤差の影響により,精度の点からは十分とはいえない｡そこで,本研究では浮腫評価のための高精度で日常的な使用に適した体肢容積計を開発した｡この測定原理はアルキメデスの原理を適用したもので,水を入れた水槽に測定部位を入れる前後の質量変化により,その容積を量るしくみである｡まず,この容積計の出力の線形性,分解能,安定性,再現性について検討を行った｡この結果,本装置の仕様は最大計測容積25,000cm(3),分解能1cm(3),非直線性0.007%以下となり,非常に高精度であるといえる｡また,被験者3名の足部,下腿部の容積の日内変化を測定した結果,各被験者の容積変化の特徴を明らかにすることができ,浮腫評価への応用ができることを確認した。

Quantitative evaluation of the edema is important for perinatal medicine. In a conventional method, the volume of human limb has been estimated by 2 circumferences of the measurement position, which is measured with the tape measure. However, the following errors makes this measurement insufficient; ・the error by the way of winding of a measure to the measurement position, ・the error between volume of model geometry of measurement position and one of real shape of measurement position and so on. Then, we have developed a volume meter of human limb for the edema evaluation, which is high precision and suitable for the everyday use. Archimedes' principle was applied as this measurement principle. The mass change of water tank with water, when the measurement part water in, was converted to volume of measurement part. The linearity, resolution, stability. reproducibility of the volume meter was investigated. Considering these results, we found that the specification of this equipment was high precise as follows; maximum volume of 25,000 cm(3), resolution of 1 cm(3), nonlinearity of 0.007%. We also measured the diurnal volume change of foot and lower leg in three subjects. We found that the differences between foot and lower leg or among the subjects. The developed volume meter can be expected to apply to quantitative evaluation of the edema.