Abstract
Body composition analysis is important in assessing nutritional status in both health and disease. This study used deuterium oxide and sodium bromide to determine total body water and extracellular water, respectively. These criterion methods were used in conjunction with bioelectrical impedance spectroscopy (BIS) to develop equations for predicting compartments of body water from BIS. Additionally, deuterium oxide was quantified in respiratory moisture to determine if correction factors for this route of isotope loss was necessary. Sodium bromide concentrations at 90 minutes and 180 minutes were tested for statistical equivalency to determine if NaBr had equilibrated by 90 minutes. Finally, impedance measured with electrodes separated by 2.5, 5, 10, 15, 20, and 25 cm was examined for change in measured impedance. Twelve healthy adult dogs, weighing 19.2 to 31.6 kg, were used for this study. Respiratory moisture was collected in 30 minute intervals during the 90 minutes required for D2O to equilibrate in serum. Respiratory moisture was determined to contain less than 0.1% of the overestimation of isotope loss. Thus, no correction factors for respiratory loss of isotope were deemed necessary. Serum concentration of NaBr at 90 and 180 minutes were determined to be equivalent. Impedance measured at the electrode separation distances between 2.5 and 20 cm was determined to be statistically different. Equations for calculation of extracellular and total body water were developed, although an equation for intracellular water could not be derived.
Witten, Tiffani Tipton (2000). Isotope loss from exhaled moisture and correlation of multifrequency bioelectrical impedance to body fluid compartments measured by intravenous deuterium oxide and sodium bromide dilution in dogs. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -W385.