A computer-based bioelectrical impedance spectroscopic system for noninvasive assessment of compartmental fluid redistribution

Bioimpedance methods using fixed frequency stimulation to measure volume changes and hemodynamic parameters in body segments of human subjects under various conditions of body position and orthostatic stress are discussed. An electrical impedance spectroscopic (EIS) system has been developed to allow extension of these studies to include examination of the redistribution of fluids between the intracellular and extracellular compartments of the monitored body segments. Evaluated in studies of the human calf and thigh during 90 min of 6° or 10° head-down bed rest, the system promises to enable tracking of segmental and compartmental fluid redistribution in response to various environmental and physiological stresses with both temporal and anatomic resolution greater than that attainable with other methods