Do dialysate conductivity measurements provide conductivity clearance or ionic dialysance?
1Department of Biophysics, University Pierre et Marie Curie, and Hemodialysis Units, AURA, Paris, France. thierry.petitclerc@auraparis.org
Kidney International
|September 21, 2006
Summary
Dialysate conductivity measurements estimate urea clearance during hemodialysis. The term "ionic dialysance" is more appropriate than "conductivity clearance" for these measurements, reflecting solute transfer capabilities.
Area of Science:
- Nephrology
- Biomedical Engineering
- Clinical Chemistry
Background:
- Dialysate conductivity measurements are used for on-line estimation of urea clearance in hemodialysis.
- Existing literature uses terms like 'conductivity clearance' and 'ionic dialysance' for these measurements.
- Clarification is needed on the most appropriate terminology to accurately reflect the underlying physiological process.
Purpose of the Study:
- To differentiate between the concepts of clearance and dialysance in the context of hemodialysis.
- To determine the most appropriate term for measurements derived from dialysate conductivity.
- To evaluate the relationship between ionic dialysance and urea clearance.
Main Methods:
- Reviewing the definitions of clearance and dialysance.
- Analyzing the impact of ultrafiltration on solute transfer.
- Comparing urea clearance with ionic dialysance derived from conductivity measurements.
Main Results:
- Clearance measures depuration efficacy, while dialysance measures solute transfer capability between blood and dialysate.
- The definition of dialysance should be generalized to include ultrafiltration.
- For solutes absent in the dialysate (like urea), clearance equals dialysance.
- Conductivity measurements reflect electrolyte dialysance, which is lower than their clearance due to ion addition in dialysate.
- Ionic dialysance is a more appropriate term than conductivity clearance.
Conclusions:
- Ionic dialysance is the more appropriate term for measurements derived from dialysate conductivity.
- Ionic dialysance provides a good estimation of urea clearance during hemodialysis.
- Accurate terminology is crucial for understanding and interpreting hemodialysis efficiency parameters.
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