새로운 생체 전기 임피던스법

Abstract

A new bioelectrical impedance method has been developed and evaluated. The electrodes were made of stainless steel and electrical interfaces were created by an upright subject gripping hand electrodes and stepping onto foot electrodes. Eight tactile electrodes were in contact with surfaces of both hands and feet; thumb, palm and fingers, front sole, and rear sole. Automatic on-off switches were used to change current pathways and to measure voltage differences for target segments. Segmental body resistances and whole body resistance(RWHOLE) were measured in 60 healthy subjects. Segmental resistances of right arm(RRA), left arm(RLA), trunk(RT), right leg(RRL) and left leg(RLL) were 310.0 ± 61.6 Ω, 316.9 ± 64.6 Ω, 25.1 ± 3.4 Ω, 236.8 ± 31.2 Ω and 237.6 ± 30.4 Ω, respectively. Individual segmental impedance indexes(Ht2/RRA, Ht2/RT, and Ht2/RLA) were closely related to lean body mass(LBM) as measured by densitometry ranged from r= 0.925 to 0.960. Ht2/(RRA+ RT+RLA) predicted LBM slightly better(r = 0.969) than the traditional index, Ht2/RWHOLE(r = 0.964), supporting the accuracy of the segmental measurement. A multiple regression equation utilizing Ht2/RRA, Ht2/RT and Ht2/RRL predicted LBM with r = 0.971. Ht2/RRA term of the regression contributed to mere than 40% of the LBM prediction, indicating that lean mass of arm represented whole body LBM more closely than other body segments. The new electrode method was characterized by upright posture, eight tactile electrodes, segmental measurements and utilization of electronic switches in comparison with the conventional method. The measurement with this new method was extremely reproducible, quick and easy to use.