Abstract
Measurement of total body electrical conductivity (TOBEC) a new non-invasive method for the determination of fat-free mass, operates on the principle that body fluids perturb an electromagnetic field proportional to their conductivity, which is dependent on the amount of the different cations and anions present. We evaluated whether differences between the conductivities of intracellular-(ICF) and extracellular body fluids (ECF) can be measured with the TOBEC instrument (EM-Scan, HP-2). Solutions were made up to approximate the concentrations of ions that are present in ICF and ECF. Phantoms (flat plastic bags) containing solutions with ICF:ECF (%) ratios of a) 30:70 (premature infant); b) 39:61 (term newborn infant) and c) 44:56 (infant, 6months of age) were made for each of the volumes 0.5, 1,2 and 3 liters. Three regression lines were calculated from the TOBEC readings obtained from the phantoms containing solutions a, b or c. Significant differences between the three regression lines indicated that even small differences in ICF:ECF ratios at volumes between 0.5 - 3 liters can be measured with the TOBEC instrument. Our findings further indicate that the fat-free mass of premature infants derived from TOBEC measurements will be systematically overestimated unless age specific ICF:ECF ratios are introduced into the prediction equations.
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Huemer, C., Haschke, F. & Huemer, K. TOBEC DISCRIMINATES BETWEEN EXTRA- AND INTRACELLULAR BODY FLUIDS. Pediatr Res 27, 537 (1990). https://doi.org/10.1203/00006450-199005000-00074
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DOI: https://doi.org/10.1203/00006450-199005000-00074