Three-frequency Bioimpedance Method of Evaluating Extracellular and Intracellular Fluid Volumes, Fat and Muscle Mass Parameters on Groups of Patients with Untypical Body Structure

Impedance measurement is the perspective method for biology and medicine and is called in general bioimpedance analysis. Some problems in placement of electrodes and standardization of procedure require decision. In particular, the existing dual-frequency bioimpedance analysis methods have several significant shortcomings, related to the assumptions in their physical models: cell membrane capacity reactance is excluded from the three-component body conductivity model and compensated by special statistical correction formula. The use of the third frequency is suggested as a necessary and sufficient condition for correct estimation of the capacitive reactance of the human body segment, extracellular and intracellular fluid resistances. The three-frequency bioimpedance analysis enables to increase accuracy of evaluating extracellular and intracellular fluid volumes and other body composition parameters to control treatment of patients with untypical body structure by more accurate estimation of capacity reactance of a cell membrane. The Proposed method was tested on several groups of patients with untypical body structure and showed better accuracy in comparison with the two-frequency bioimpedance analysis in evaluating intracellular fluid volume, fat and muscle mass parameters. The three-frequency bioimpedance analysis is applicable to take measurements on peripheral edema patients as a group of patients with untypical structure of limb segments.