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Review
. 2021 Aug 1;27(4):344-353.
doi: 10.1097/MCC.0000000000000840.

Bioelectric impedance analysis for body composition measurement and other potential clinical applications in critical illness

Hanneke Pierre Franciscus Xaverius Moonen  1 , Arthur Raymond Hubert Van Zanten  1   2
Affiliations
Review

Bioelectric impedance analysis for body composition measurement and other potential clinical applications in critical illness

Hanneke Pierre Franciscus Xaverius Moonen et al. Curr Opin Crit Care. .

Abstract

Purpose of review: Insight into body composition is of great value in the ICU. Bioelectric impedance analysis (BIA) is the most applicable bedside technique. However, bioimpedance has not been validated in the critically ill, and the interpretation of the measurements poses challenges. This review discusses the potential clinical applications of BIA and explores caveats and solutions to its use in the intensive care setting.

Recent findings: A correlation is repeatedly found between raw impedance parameters, fluid ratios, overhydration, and adverse outcome of critical illness. However, cut-off and reference values remain elusive. Experience with BIA-guided fluid management in the ICU is limited. BIA-derived muscle mass appears a promising biomarker for sarcopenia, correlating well with CT-analysis. Body cell mass and fat-free mass provide potential use in estimation of metabolic rate, protein requirements and pharmacokinetics. Several methods of reducing bias in BIA parameters in critical illness require validation.

Summary: There are currently too many uncertainties and discrepancies regarding interpretation of bioimpedance in critical illness, to justify therapeutic consequences. However, there are several promising areas of research, concerning some of the most urgent clinical problems in intensive care, emphasizing the need to evaluate further the use and interpretation of bioimpedance in the intensive care setting.

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Conflict of interest statement

H.P.F.X.M. has no conflicts of interest to disclose. A.R.H.V.Z. reported that he had received honoraria for advisory board meetings, lectures and travel expenses from Abbott, Amomed, Baxter, Cardinal Health, Danone-Nutricia, DIM-3, Fresenius Kabi, Lyric, Mermaid and Nestle-Novartis. Inclusion fees for patients in nutrition trials were paid to the local ICU research foundation.

Figures

Box 1
Box 1
no caption available
FIGURE 1
FIGURE 1
Low-frequency currents will not penetrate cell membranes, and as such will measure extracellular water impedance. High-frequency currents will go through cells, at which point the impedance reflects total body water (TBW).
FIGURE 2
FIGURE 2
When an electric current passes a cell membrane, reactance causes a time delay, creating a phase shift between voltage and current. The phase angle describes this difference between the voltage and the current. A high-phase angle is, therefore, consistent with large quantities of intact cell membranes and body cell mass.
FIGURE 3
FIGURE 3
Bioelectric impedance vector analysis relates the length and direction of the phase angle to that of a reference population, enabling a visual interpretation of the clinical relevance of the raw bioelectric impedance analysis values.
FIGURE 4
FIGURE 4
Earlier bioelectric impedance analysis devices regarded the body as one cylinder, calculating body water volumes based on whole-body impedance and body height. Segmental BIA devices consider the body as five separate cylinders and use electrodes on all limbs, improving accuracy. BIA, bioelectric impedance analysis.
FIGURE 5
FIGURE 5
Overview of the relationship between several frequently used derived body composition parameters, based on a multicompartment body composition model. Definitions may vary slightly between sources and device manufacturers.
See this image and copyright information in PMC

References

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