Optimisation of Solute Removal and Water Usage in Paediatric Haemodialysis

Children undergoing haemodialysis are enrolled in the study. During a mid-week dialysis session, three dialysis modalities are applied sequentially for 10-15 minutes each: haemodialysis (HD), predilution haemodiafiltration (pre-HDF), and postdilution haemodiafiltration (post-HDF). For each modality, the dialysate-to-blood flow ratio is adjusted to approximately 1.0, 1.5, and 2.0.

For each setting, blood samples are collected from the blood inlet and outlet lines, and dialysate samples are taken from the spent dialysate line. All sampling is performed within the first hour of the dialysis session.

All samples are analysed for a range of uraemic toxins, including small water-soluble solutes, middle molecules, and protein-bound toxins. Using inlet and outlet blood concentrations, the extraction ratio is calculated for each setting. Based on the dialysate flow rate, total water usage for a full dialysis session is estimated. Together, these calculations allow determination of the optimal dialysate-to-blood flow ratio that provides the highest dialyser clearance with the lowest relative water consumption.

Inclusion criteria

• not older than 18 years old
• at least three months of stable hemodialysis

Exclusion criteria

• a non well-functioning vascular access
• infections at the study week