The electric resistivity of human tissues (100 Hz-10 MHz): a meta-analysis of review studies

Abstract

The electric resistivity of various human tissues has been reported in many studies, but on comparison large differences appear between these studies. The aim of this study was to investigate systematically the resistivities of human tissues as published in review studies (100 Hz-10 MHz). A data set of 103 resistivities for 21 different human tissues was compiled from six review studies. For each kind of tissue the mean and its 95% confidence interval were calculated. Moreover, an analysis of covariance showed that the calculated means were not statistically different for most tissues, namely skeletal (171 omega cm) and cardiac (175 omega cm) muscle, kidney (211 omega cm), liver (342 omega cm), lung (157 omega cm) and spleen (405 omega cm), with bone (> 17,583 omega cm), fat (3,850 omega cm) and, most likely, the stratum corneum of the skin having higher resistivities. The insignificance of differences between various tissue means could imply an equality of their resistivities, or, alternatively, could be the result of the large confidence intervals which obscured real existing differences. In either case, however, the large 95% confidence intervals reflected large uncertainties in our knowledge of resistivities of human tissues. Applications based on these resistivities in bioimpedance methods, EEG and EKG, should be developed and evaluated with these uncertainties in mind.

Electrical impedance myography to assess outcome in amyotrophic lateral sclerosis clinical trials

“…The four-electrode technique, coupled with distant placement of the current electrodes and high-impedance input circuitry, reduces the contribution of the skin and the subcutaneous fat to a negligible level (Shiffman et al, 1999). Moreover, of all tissues in a limb, muscle contributes by far the greatest extent to the EIM data since is has a very low resistivity (Faes et al, 1999) and relativity large volume, thus serving as the preferential path for electrical current flow.…”

Ethnic differences in the association between body mass index and impedance index (Ht2/Z) in adult women and men using a leg-to-leg bioimpedance method

“…The leg-to-leg bioimpedance is a rapid and noninvasive method to assess body composition (Nunez et al, 1997) and this is the first study to compare this method in different ethnic groups living within their native countries. The larger increase in impedance index per unit increase of BMI -showed by the different slopes and interceptsobserved in West African and Asian Indian women compared with white Caucasian women may arise from an increased bone mineral content and/or adiposity -both of which are less hydrated and thus have higher resistance (Faes et al, 1999). This speculation is supported by previous studies which have shown an increased body mineral content in African populations (Barondess et al, 1997;Wagner and Heyward, 2000) and a higher adipose tissue in Asian Indians compared to white Caucasians (Bose, 1995;Orr-Walker et al, 2005;Bhansali et al, 2006).…”

“…The human body can be divided into different components (fat, mineral, protein and water) which have specific physical properties and show a characteristic response to the application of a small, electrical current, as used in bioimpedance analysis (BIA) (Faes et al, 1999;Ellis, 2000). BIA has emerged as one of the most widely used methods to assess body composition because it is quick, can be undertaken in the field and is relatively inexpensive.…”

Micro electrical impedance spectroscopy on a needle for ex vivo discrimination between human normal and cancer renal tissues

“…The frequency range was decided by referring to the previous studies that are relevant to the electrode polarization in low frequencies. [19][20][21][22][23] An operating voltage of 100 mV rms was applied to the electrodes considering the induced voltage that can cause damage to the bio-tissues. 24 The needle and the sample had a floating potential with respect to the electrodes.…”