Validity and Reliability of an Impedance Meter Device for the Assessment of Neuromuscular Rehabilitation Therapies

Abstract

During neuromuscular rehabilitation treatments, it is necessary to evaluate the evolution of the patients using objective parameters. This requires the design of devices that generate valid and reliable data about the neuromuscular system. In this study, an impedance meter device is introduced, that was designed to measure complex impedance for biomedical applications. Furthermore, the reliability of the device was investigated, using reliability indexes derived from the estimation of the standard error of measurement (SEM), such as the coefficient of variation (CV) and Bland-Altman limits of agreement (LoA). Reliability was tested using electrical models of the neuromuscular system over a range of impedances from 40 to 1700 W and within a frequency interval ranging from 5 to 100 kHz. Results showed that the maximum difference between the measured values and the calculated values (using precision instruments) was below 2,5%. Regarding reliability, typical error (CV) was below 0,45% of the measured value, whereas the maximum error (LoA) was below 2,5% of the measured value. In conclusion, the impedance meter device presented in this work is sufficiently reliable for use in biomedical applications that involve measurement of complex impedances.