A new technique for low-volume continuous sampling of spent dialysate: a validation study

Area of Science:

• Nephrology
• Biomedical Engineering
• Clinical Chemistry

Background:

• Current hemodialysis (HD) adequacy measures like Kt/V-urea have limitations.
• The gold standard, total dialysate collection (TDC) for direct dialysis quantification (DDQ), is impractical for routine clinical use.

Purpose of the Study:

• To validate a novel low-volume continuous sampling of spent dialysate (CSSD) technique for measuring HD adequacy.
• To compare the accuracy of CSSD against TDC for quantifying urea removal.

Main Methods:

• A cross-sectional study involving 20 HD sessions at a university hospital.
• Urea removal was measured using three DDQ methods: TDC, CSSD, and fractional sampling of dialysate (FSD).
• Statistical analysis included linear regression and Bland-Altman concordance.

Main Results:

• CSSD accurately measured urea removal, with results closely matching the TDC gold standard (r=0.96, p<0.0001).
• The mean urea collected by TDC was 33.70±11.70 g, while CSSD calculated 33.90±11.70 g.
• Anthropometric estimation of urea distribution volume (UDV) underestimated UDV in smaller patients compared to DDQ methods.

Conclusions:

• The CSSD technique is a simple, inexpensive, and accurate method for assessing total solute removal during hemodialysis.
• CSSD offers a practical alternative for monitoring HD adequacy in clinical settings.