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Dialysate calcium loss using a calcium free dialysate
1Division of Nephrology, Montreal General Hospital, Canada.
The International Journal of Artificial Organs
|July 1, 1994
Summary
Dialysis removes significant amounts of calcium, averaging nearly 2g per session, with losses plateauing at higher blood flow rates. Actual dialyzer performance for urea, creatinine, and phosphate is lower than manufacturer specifications.
Area of Science:
- Nephrology
- Biomedical Engineering
- Materials Science
Background:
- Calcium balance is crucial during hemodialysis.
- Dialyzer performance can vary significantly, impacting solute removal.
Purpose of the Study:
- To quantify calcium loss during hemodialysis across various dialyzers and blood flow rates.
- To compare the in vivo clearances of urea, creatinine, phosphate, and calcium with manufacturer specifications.
Main Methods:
- Fifteen dialyzers were tested with a calcium-free dialysate at blood flow rates (QB) of 100-400 ml/min.
- Solute clearances were measured over a 4-hour period.
- Calcium loss and clearances of urea, creatinine, and phosphate were analyzed.
Main Results:
- Calcium loss in dialysate plateaued at QB 200 ml/min, averaging approximately 2g per 4-hour session.
- Creatinine, phosphate, and calcium clearances correlated linearly with urea clearance (r=0.946, 0.810, 0.808).
- In vivo urea clearance was ~20% lower, and creatinine/phosphate clearances ~30% lower than manufacturer specifications.
Conclusions:
- Hemodialysis leads to substantial calcium loss, which does not increase beyond a QB of 200 ml/min.
- In vivo dialyzer performance is consistently lower than in vitro specifications, necessitating adjustments in treatment protocols.