Nutritional assessment: Whole body impedance and body fluid compartments

Measures of total body water and extracellular fluid volume would provide valuable information for the assessment of nutritional status in patients. Time and cost factors make the use of tracer dilution techniques impractical in routine nutritional assessment batteries. Some studies suggest that measurements of the electrical impedance properties of the body can be used to estimate total body water and extracellular fluid volume. The observed and predicted relationships between whole body impedance and body fluid compartment volumes are discussed, and problems which may limit the accuracy of prediction of body fluid compartment volume from whole body impedance measures are discussed. With further improvements, whole body impedance measurement could provide a practical bedside method for measurement of body fluid compartment volumes.