Haemodilution with dextran 40 and hydroxyethyl starch and its effect on cerebral microcirculation

Area of Science:

• Physiology
• Pharmacology
• Neuroscience

Background:

• Hemodilution is a technique used to reduce blood viscosity.
• Cerebral blood flow (CBF) is crucial for brain function and oxygen delivery.
• Different fluid resuscitation agents have varying effects on hemorheology and blood flow.

Purpose of the Study:

• To investigate the impact of hemodilution with Ringer's solution, hydroxyethyl starch (HAES), and dextran 40 on CBF in cats.
• To determine the relationship between hematocrit (Hct) and CBF during hemodilution.
• To elucidate the mechanisms underlying changes in CBF following hemodilution.

Main Methods:

• Ten cats were used to measure CBF using the hydrogen clearance technique.
• Hemodilution was induced using Ringer's solution, 10% HAES 200/0.5, and dextran 40.
• Hematocrit levels and CBF were monitored throughout the experiment.

Main Results:

• Hemodilution with HAES and dextran 40 resulted in a significant increase in CBF (25% and 35%, respectively).
• Ringer's solution did not produce a significant change in CBF.
• CBF was strongly correlated with hematocrit, indicating a reduction in oxygen-carrying capacity.

Conclusions:

• The observed increase in CBF during hemodilution is primarily mediated by a regulatory mechanism responding to reduced oxygen-transport capacity, rather than changes in rheological parameters.
• HAES and dextran 40 are more effective than Ringer's solution in increasing CBF through hemodilution.
• Hematocrit is a key determinant of CBF during hemodilution, influencing oxygen delivery to the brain.