Accuracy of Bioelectrical Impedance Analysis in Estimation of Extracellular Space in Healthy Subjects and in Fluid Retention States

Abstract

Bioelectrical impedance analysis (BIA) is a noninvasive method recently introduced for body fluid evaluation in healthy subjects. The purpose of this paper is to verify the reliability of bioelectrical measurements in extracellular water (ECW) prediction in healthy subjects and in fluid retention states. We studied 40 subjects (19 males and 21 females) aged 21-81 years; 22 were healthy subjects, 12 were affected by chronic heart failure, and 6 by chronic renal failure. In all subjects resistance (R) and reactance (Xc) at 1 and 50 kHz corrected for height were compared with ECW measured by the bromide dilution method. Our results suggested a different behavior of the current in fluid-retention states with respect to healthy subjects. ECW was best predicted by resistance at 1 kHz corrected for height, group (considered as dummy variable), weight and gender (R² = 0.89, p < 0.001, SEE = 1.7 liters). The bioelectrical impedance analysis at 50 kHz explained the 89% of ECW variability when resistance and reactance corrected for height are considered with gender group and weight (R² = 0.89, p < 0.001, SEE = 1.7 liters). In conclusion, the bioelectrical method at 1 kHz can be considered sufficiently accurate in ECW prediction in healthy subjects and in fluid retention states. Also, the bioelectrical impedance analysis at 50 kHz is useful for predicting ECW, but his role must be further investigated.

Fluid Management in the Intensive Care Unit: Bioelectrical Impedance Vector Analysis as a Tool to Assess Hydration Status and Optimal Fluid Balance in Critically Ill Patients

“…BIVA was originally applied to healthy individuals in order to establish normal values for resistance and reactance. These values have been used to construct confidence intervals in the form of ellipses [21,22]. A special software was developed to finally convert these parameters into a synthetic measure of body hydration percentage, which allows for a simpler interpretation.…”

Monitoring Fluid Status at the Outpatient Level: The Need for More Precision

“…Given that the major concern is emerging fluid retention, attention has turned to the potential role of bioelectrical impedance. 12,13 Impedance is a measure of resistance to flow of an electrical current. It can be measured by multiple methods and has been shown to accurately reflect hydration status in patients with renal, cardiac, and liver disease.…”

“…It can be measured by multiple methods and has been shown to accurately reflect hydration status in patients with renal, cardiac, and liver disease. 12,13 Impedance is derived from 2 measurements, electrical resistance and reactance. As patients become fluid-overloaded, both of these parameters decrease, reflecting improved conductivity of electrical current.…”

Application of bioelectrical impedance to sports science

“…Segmental BIA, or whole-body BIA, in states of altered hydration and the estimation of muscle mass have also been developed. Since these measurements are relatively inexpensive, noninvasive and have high accuracy, they have been applied in various research fields, including sports medicine 3,4) . Herein, the merits and limitations of the BIA method are discussed, and research introduced which has been performed in the field of sport sciences.…”