Reverse mid-dilution: new way to remove small and middle molecules as well as phosphate with high intrafilter...

Area of Science:

• Nephrology
• Biomedical Engineering

Background:

• Small and middle molecule removal is crucial for haemodialysis (HD) patient survival.
• Mid-dilution (MD) provides high diffusive-convective clearances but can increase intrafilter blood pressure.
• A novel reverse MD configuration was developed to address pressure-related limitations of standard MD.

Purpose of the Study:

• To compare the biochemical and technical performance of reverse MD against standard MD.
• To evaluate the efficacy of reverse MD in removing small and middle molecules.
• To assess the impact of reverse MD on intrafilter blood pressures.

Main Methods:

• Eight HD patients participated in a crossover study comparing standard MD and reverse MD treatments.
• Instantaneous clearance and total mass removal of urea, phosphate, beta2-microglobulin, and angiogenin were measured.
• Dialysate and blood pressures were monitored throughout the treatments, with a reinfusion rate set at 6 l/h.

Main Results:

• Both standard MD and reverse MD demonstrated statistically comparable, high absolute removals of target molecules.
• Reverse MD resulted in significantly lower inlet blood pressures (595+/-119 mmHg) compared to standard MD (731+/-222 mmHg).
• Transmembrane pressures were also lower in reverse MD across both stages of filtration.

Conclusions:

• Reverse MD is a promising technique for high ultrafiltration haemodialysis, potentially eliminating the need for external fluid reinfusion.
• The configuration allows for substantial removal of small and middle molecules while maintaining lower intrafilter pressures.
• Reverse MD offers an improved technical profile for routine haemodialysis treatments.