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Summary
Commercial dextran solutions are hyperoncotic, not isoncotic as expected. Diluting 6% dextran with saline creates an isoncotic solution, crucial for accurate clinical use.
Area of Science:
- Biochemistry
- Pharmacology
- Veterinary Medicine
Background:
- Dextran solutions are commonly used plasma expanders.
- The oncotic properties of dextran are critical for its efficacy.
- Previous assumptions suggested commercial dextran preparations were isoncotic.
Purpose of the Study:
- To evaluate the oncotic pressure of commercial dextran solutions.
- To determine if dextran preparations are isoncotic.
- To investigate methods for achieving isoncotic dextran solutions.
Main Methods:
- Plasma volume measurements before and after dextran infusion in dogs.
- Preparation of a 3% dextran solution by mixing 6% dextran with 0.9% saline.
- Assessment of oncotic pressure of commercial and prepared dextran solutions.
Main Results:
- All tested commercial dextran brands were hyperoncotic (approximately 2x).
- A 3% dextran solution, created by a 1:1 mix of 6% dextran and saline, was nearly isoncotic in dogs.
- The hyperoncotic nature is likely due to a high proportion of lower molecular weight dextran molecules.
Conclusions:
- Commercial dextran preparations may not be isoncotic as commonly believed.
- The presence of lower molecular weight dextran contributes to unexpected oncotic pressure.
- Clinicians and researchers must verify the oncotic status of dextran solutions for accurate administration.