Determination of body fluids by the impedance technique

D. A. Schoeller*, R. F. Kushner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

For the purposes of determining body composition, the body can be viewed as the sum of two components, fat and fat-free mass, the latter including water, protein, and minerals. Current methods for determining the size of these various components of the body are either inexact, invasive, or dependent on expensive or slow instrumentation. Bioelectrical impedance, which is rapid, noninvasive, and relatively inexpensive is examined as an alternative method for measuring body composition. The potential for the impedance technique arises from the very different electrical properties of the body components. The theory of bioelectrical impedance analysis is briefly presented, and human applications are discussed. The results of studies validating the method are cited.

Original languageEnglish (US)
Pages (from-to)19-21
Number of pages3
JournalIEEE Engineering in Medicine and Biology Magazine
Volume8
Issue number1
DOIs
StatePublished - 1989

Funding

By measuring reactance and employing both a low-and high-frequency current, bioimpedance has an even greater potential of measuring body composition. As indicated above, this technique would give measures of extracellular water and total body water which lend themselves to a three-compartment model (i.e.. intracellular mass, extracellular mass, and fat mass). This model would be particularly useful in the assessment of body composition in the emaciated patient and those undergoing nutritional restitution, where an abnormal extracellular masshntracellular mass ratio is found. Preliminary studies from McDougal et al. [I 51 and Segal et al. [I61 support the utility of bioimpedance under these conditions. CONCLUSIONS Bioimpedance analysis is a rapid, portable, reliable and simple-to-operate method that improves the accuracy of predicting total body water and fat-free mass compared to other traditional anthropometric techniques. Although there is a general uniformity regarding the predictive variables generated by the multiple regression equations, the individual coefficients differ since they are population specific. There is an increased need to pool subject data so as to develop a generally accepted equationk) with wide applicability. In addition, validation studies must be conducted in subjects with nutritional disorders that affect body water. These studies should also include measurement of the intracellular and extracellular water compartments. ACKNOWLEDGMENT This work was supported by NIH Grant No. DK26678. REFERENCES

ASJC Scopus subject areas

  • Biomedical Engineering

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