Feasibility study using longitudinal bioelectrical impedance analysis to evaluate body water status during fluid resuscitation in a swine sepsis model

Abstract

Fluid resuscitation is crucial in the initial management of sepsis; however, little is known about the serial changes and overall distribution of fluids administered into the body. To identify the feasibility of longitudinal bioelectrical impedance analysis during fluid treatment, a preclinical porcine model of Escherichia coli-induced sepsis was used. After sepsis induction, pigs were treated with fluid and vasopressors and monitored for up to 12h after bacterial infusion or until death. Bipolar electrodes for bioelectrical impedance analysis were attached to the left extremities and measurements were performed every 10min. Among the 12 subjects, 7 pigs expired during the experiment, and the median survival was 9.5h. As sepsis progressed with an increase in cumulative fluid balance, R0 [∝ 1/extracellular water (ECW)] decreased, while Ri [∝ 1/intracellular water (ICW)] and ratio of extracellular water to total body water (ECW/TBW) increased. The phase angle constantly decreased throughout the monitoring period, and all non-survivors died when the phase angle decreased by more than 10%. Among the variables, ΔR0 and Δphase angle showed moderate negative correlations, and ΔECW/TBW showed a moderate positive correlation with the hourly fluid balance. Compared to survivors, a greater increase in ΔECW/TBW and a decrease in phase angle were observed in non-survivors over time, with an increase in cumulative fluid balance. Differences in ΔECW/TBW and phase angle emerged at 240min when the difference in cumulative fluid balance between the two groups (survivors vs non-survivors) exceeded 1000mL. In conclusion, continuous measurements of bioelectrical impedance analysis in a porcine sepsis model are feasible and may reflect changes in the body water profile during fluid resuscitation.