Does the optimization of cardiac output by fluid loading increase splanchnic blood flow?

Area of Science:

• Critical Care Medicine
• Hemodynamics
• Gastroenterology

Background:

• Septic shock is characterized by circulatory dysfunction, including altered splanchnic blood flow.
• Optimizing cardiac output is a key goal in managing septic shock.
• The relationship between increased cardiac output and splanchnic perfusion in stabilized septic shock requires further elucidation.

Purpose of the Study:

• To investigate the impact of fluid-induced increases in cardiac output on splanchnic blood flow in hemodynamically stabilized septic shock patients.
• To assess changes in gastric mucosal blood flow and related parameters following fluid loading.

Main Methods:

• Utilized transpulmonary thermo-dye-dilution to measure cardiac index (CI), intrathoracic blood volume (ITBV), and total blood volume (TBV).
• Employed the steady-state indocyanine-green technique with a hepatic venous catheter to measure splanchnic blood flow.
• Estimated gastric mucosal blood flow via regional carbon dioxide tension (PRCO2) and calculated the PCO2-gap.

Main Results:

• Fluid loading increased total blood volume index, intrathoracic blood volume index, and cardiac index.
• Splanchnic blood flow, both absolute and fractional, did not significantly change despite increased cardiac output.
• Gastric mucosal PRCO2 and the PCO2-gap showed a slight increase, suggesting potential alterations in mucosal perfusion or metabolism.

Conclusions:

• Increasing cardiac output through fluid loading in stabilized septic shock patients does not guarantee an improvement in splanchnic blood flow.
• Splanchnic perfusion may not directly correlate with overall cardiac output in this patient population.
• Further research is needed to understand the mechanisms limiting splanchnic blood flow augmentation despite increased cardiac output.