A COMPARISON OF 4 COMMERCIAL SYSTEMS USED TO MEASURE WHOLE-BODY ELECTRICAL-IMPEDANCE

Four commercial whole-body impedance measuring systems (Holtain, RJL, Bodystat and EZcomp) were compared on two separate occasions for a gro up of normal subjects. The first set of readings in 21 subjects demons trated a significant difference of approximately 6% between the Holtai n measurement and the higher reading from the Bodystat or RJL systems. The differences between the RJL and Bodystat readings were much less (mean difference 0.6%). Similar differences between the Holtain and EZ comp or Bodystat measurements were demonstrated on a second occasion f or a group of 11 subjects. Given that these devices operate by supplyi ng a constant current, the differences may be explained by the results from a series of measurements on a whole-body resistance simulator in which it appears that for skin contact resistance > 200 Ohm the Holta in device is unable to sustain a constant current and therefore record s a lower impedance than the true value.