Endotoxemia alters splanchnic capacitance.

Area of Science:

• Physiology
• Cardiovascular System
• Sepsis Pathophysiology

Background:

• The splanchnic circulation is a significant capacitance vessel system.
• Alterations in splanchnic blood volume can impact venous return and cardiac output, particularly during hypotensive states.

Purpose of the Study:

• To investigate the effects of rapid versus slow endotoxin infusion on splanchnic blood volume.
• To determine if endotoxin shock leads to blood volume pooling within the splanchnic capacitance circulation.

Main Methods:

• Utilized 8 farm swine for the study.
• Administered endotoxin (Escherichia coli) via rapid (5 min) and slow (60 min) infusion.
• Measured blood volume using Tc99m-labeled erythrocytes and radionuclide imaging.
• Monitored mean arterial pressure (MAP) and central venous pressure (CVP).

Main Results:

• Rapid endotoxin infusion decreased splenic volume by 45% and increased liver volume by 40%, with a 60% MAP reduction.
• Slow endotoxin infusion decreased splenic volume by 50% and liver volume, with a 30% MAP reduction.
• Mesenteric volume remained unaffected; total splanchnic volume decreased with slow infusion but not rapid infusion.

Conclusions:

• E. coli endotoxin acutely reduces splenic blood volume and increases liver blood volume following hypotension.
• Endotoxin shock does not result in splanchnic blood volume pooling and may decrease total splanchnic volume.
• The splanchnic capacitance circulation is not a primary site for blood volume sequestration in this endotoxin shock model.