Tissue oxygen tension in random pattern skin flaps during normovolemic hemodilution

Area of Science:

• Biomedical Engineering
• Physiology
• Surgical Research

Background:

• Normovolemic hemodilution is a technique used to reduce hematocrit.
• Understanding its effect on tissue oxygenation is crucial for clinical applications.
• Subcutaneous tissue oxygen tension (PscO2) is a key indicator of tissue perfusion.

Purpose of the Study:

• To investigate the impact of progressive normovolemic hemodilution using Dextran 70 on PscO2.
• To compare the effects on random pattern skin flaps versus adjacent intact skin in canines.

Main Methods:

• Progressive normovolemic hemodilution with Dextran 70 was performed in canine models.
• PscO2 was measured using polarographically in implanted Silastic catheters.
• Hematocrit (HCT) levels were progressively reduced.

Main Results:

• Mean flap PscO2 was maintained down to HCT 20, while intact skin PscO2 remained stable or improved to HCT 14.
• Most flap sites showed improved PscO2 at certain HCT ranges during hemodilution.
• Greater PscO2 increments occurred at lower HCT in more ischemic areas.
• Hemodilution led to decreased peripheral resistance and increased cardiac output without significant changes in blood pressures.

Conclusions:

• Normovolemic hemodilution with Dextran 70 can preserve or improve PscO2 in canine random flaps, particularly in ischemic regions.
• The technique demonstrates potential for managing tissue oxygenation during induced anemia.
• Hemodynamic changes support the circulatory compensation during hemodilution.