Evaluation of Bioimpedance Spectroscopy for the Monitoring of the Fluid Status in an Animal Model

This study investigates the feasibility of using bioelectrical impedance measurements to detect the body fluid status. The multi-frequency impedance measurements were performed in combination with an animal experiment with five female pigs. For this purpose, the fluid balances of these animals, which were connected to an extracorporeal membrane oxygenation, were recorded. The ECMO circuit needs a high blood flow from the venous system and in order to avoid vasoconstriction in the femoral vein, blood-thinning infusions were injected. The quantity of injected fluid and the quantity of urine were recorded to monitor the fluid balance of each animal. These balances were compared with the intracellular and extra cellular tissue resistance, which was measured by bioelectrical-impedance spectroscopy. The experimental results strongly support the clinical benefit of the BIS for the assessment of changes in the hydration status.