Extracorporeal circulation exacerbates microvascular permeability after endotoxemia.

Area of Science:

• Physiology
• Critical Care Medicine
• Vascular Biology

Background:

• Extracorporeal life support (ECLS) can modestly increase microvascular permeability.
• Prior inflammatory stimuli, such as sepsis or hypoxia, markedly elevate fluid and water levels.
• The study investigates if inflammation before ECLS exacerbates microvascular protein permeability.

Purpose of the Study:

• To determine the effect of an inflammatory stimulus prior to ECLS on microvascular permeability to protein.
• To quantify changes in Starling forces and protein flux during and after ECLS in the presence of lipopolysaccharide (LPS).

Main Methods:

• Utilized an anesthetized canine lymphatic fistula model to assess Starling forces.
• Administered LPS or saline vehicle before initiating ECLS.
• Measured mesenteric microvascular permeability by elevating mesenteric venous pressure and calculating the reflection coefficient (sigma) using lymph and plasma protein concentrations.
• Calculated transvascular protein clearance and filtration coefficient (K(f)).

Main Results:

• The reflection coefficient (sigma) significantly decreased in the LPS + ECLS group (0.77 to 0.53) compared to ECLS alone (0.77 to 0.65), indicating increased permeability.
• Transvascular protein clearance increased substantially in both groups but to a greater extent in LPS + ECLS.
• The filtration coefficient (K(f)) increased significantly more in the LPS + ECLS group.

Conclusions:

• Initiation of ECLS following lipopolysaccharide (LPS) exposure significantly increases ileal microvascular permeability to both protein and water.
• The inflammatory stimulus (LPS) exacerbates the effects of ECLS on microvascular permeability compared to ECLS alone.