Microcirculatory perfusion during volume therapy. A comparative study using crystalloid or colloid in awake animals

Area of Science:

• Physiology
• Microcirculation
• Fluid Resuscitation

Background:

• Crystalloid solutions require large volumes for effective resuscitation due to fluid shift into interstitial spaces.
• This fluid shift can cause tissue edema, impairing capillary perfusion and oxygen delivery.
• The study investigates the impact of hemodilution using Ringer's lactate or dextran on tissue perfusion and oxygenation.

Purpose of the Study:

• To compare the effects of isovolemic hemodilution with Ringer's lactate versus dextran 60 on tissue perfusion and oxygenation.
• To test the hypothesis that crystalloid-induced tissue edema interferes with nutritive capillary perfusion and oxygen delivery.

Main Methods:

• Utilized a chronic dorsal skinfold window model in awake Syrian golden hamsters for in vivo microscopy of skeletal muscle.
• Employed quantitative video image analysis and surface oxygen partial pressure electrodes for physiological measurements.
• Monitored central venous and arterial pressures via chronically implanted catheters.

Main Results:

• Dextran 60 infusion resulted in no significant changes in hemodynamic parameters, capillary flow, functional capillary density, or tissue oxygen partial pressure.
• Ringer's lactate, even at a 4:1 volume ratio, reduced tissue perfusion by 62% and mean tissue oxygen partial pressure from 19 to 8 mmHg.
• Hemodynamic stability was maintained with Ringer's lactate, but at the cost of compromised tissue perfusion and oxygenation.

Conclusions:

• Artificial colloids (dextran) effectively maintained hemodynamic stability and adequate tissue oxygen supply during isovolemic hemodilution.
• Crystalloid administration (Ringer's lactate) alone compromised tissue perfusion and oxygenation in this experimental model.
• Findings suggest that colloids may be superior to crystalloids for maintaining microcirculatory function during volume resuscitation.