Low-grade hemodilution improves the microcirculatory function in surgical patients.

Area of Science:

• Physiology
• Intensive Care Medicine
• Surgical Fluid Management

Background:

• Excess interstitial fluid can impair microcirculation.
• Crystalloid fluid administration is common in surgery.
• Understanding fluid dilution effects on microcirculation is crucial.

Purpose of the Study:

• To investigate the impact of gradual plasma dilution via crystalloid infusion on microcirculatory variables.
• To assess changes in capillary filtration rate in response to plasma dilution.
• To determine optimal fluid dilution levels for surgical patients.

Main Methods:

• Video recordings of sublingual microcirculation.
• Quasi-measurements of capillary filtration rate using volume kinetic data.
• Analysis of 262 infusion experiments in 20 surgical patients.

Main Results:

• Vessel density increased up to 15-20% plasma dilution, then decreased.
• Proportion of perfused vessels (PPV) decreased by up to 15% at 20-30% dilution.
• Capillary filtration exceeded volume expansion predictions up to 15% dilution.

Conclusions:

• Plasma dilution up to 15% positively influenced vessel density and capillary filtration.
• Dilutions exceeding 15% demonstrated adverse effects on microcirculatory variables.
• Careful fluid management is essential to avoid negative impacts on microcirculation during surgery.