ID:148 FC-D07-8 Longitudinal Bioelectrical Impedance Monitoring of Body Water Redistribution in a Rat VA-ECMO Model: Interactive Effects of Sepsis and Extracorporeal Circulation

Background: Sepsis and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) can each injure endothelium and disrupt fluid distribution; together, they may represent a “double hit” that amplifies compartmental water shifts. We tested whether VA-ECMO augments time-dependent body water redistribution in experimental sepsis using longitudinal bioelectrical impedance analysis (BIA). Methods: Twenty Sprague–Dawley rats (n=5/group) were assigned to Control, Sepsis, Control+VA-ECMO, or Sepsis+VA-ECMO (2x2 factorial). Sepsis was induced with lipopolysaccharide (LPS, 10 mg/kg) 12 h before monitoring. All groups received identical stepwise intravenous priming-solution infusions (20% albumin:0.9% saline = 1:2; 6 mL). Minute-by-minute BIA yielded impedance-derived indices of total body water (TBW), intracellular water (ICW), extracellular water (ECW), and phase angle (PA). Linear mixed-effects modeling and difference-in-differences (DiD) contrasts quantified VA-ECMO–by–sepsis interaction. Results: Sepsis alone decreased TBW and ICW without consistent ECW expansion. VA-ECMO alone increased ECW and reduced PA. In Sepsis+VA-ECMO, TBW, ICW, and ECW increased in later phase with downward PA trajectory. DiD confirmed amplification beyond additivity at study end (TBW +0.126, ICW +0.170, ECW +0.061; p < 0.05). Conclusion: In this rat model, VA-ECMO in septic milieu produced double-hit effect, amplifying time-dependent fluid distribution imbalance detected by longitudinal BIA.