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Reliability of multiple frequency bioelectrical impedance analysis: An intermachine comparison

1997; Wiley; Volume: 9; Issue: 1 Linguagem: Inglês

10.1002/(sici)1520-6300(1997)9

1520-6300

Leigh C. Ward, Nuala M. Byrne, K. Rutter, L. Hennoste, Andrew P. Hills, Bruce Cornish, Brian Thomas,

Hemodynamic Monitoring and Therapy

The technical reliability (i.e., interinstrument and interoperator reliability) of three SEAC-swept frequency bioimpedance monitors was assessed for both errors of measurement and associated analyses. In addition, intraoperator and intrainstrument variability was evaluated for repeat measures over a 4-hour period. The measured impedance values from a range of resistance-capacitance circuits were accurate to within 3% of theoretical values over a range of 50-800 ohms. Similarly, phase was measured over the range 1°-19° with a maximum deviation of 1.3° from the theoretical value. The extrapolated impedance at zero frequency was equally well determined (±3%). However, the accuracy of the extrapolated value at infinite frequency was decreased, particularly at impedances below 50 ohms (approaching the lower limit of the measurement range of the instrument). The interinstrument/operator variation for whole body measurements were recorded on human volunteers with biases of less than ±1% for measured impedance values and less than 3% for phase. The variation in the extrapolated values of impedance at zero and infinite frequencies included variations due to operator choice of the analysis parameters but was still less than ±0.5%. Am. J. Hum. Biol. 9:63-72 © 1997 Wiley-Liss, Inc.