During haemodialysis your blood travels through a special filter called a dialyser before being returned to your body.
The dialyser has many tiny fibers (tubes). As the blood pumped into dialyser it flows throgh the fibers. Each fibre has tiny pores in its walls. A special fluid called dialysate washes around the fibres. The dialysate does not come into direct contact with your blood. The extra water and waste products you don’t need travel from your blood through the fibre pores and into dialysate. Clean blood flows back to your body. The dialysate goes down the drain.
Some dialysis machines are suitable for haemodiafiltration, which is a specialised type of dialysis. During haemodiafiltration, the machine removes more water from the blood than during “normal” haemodialysis. The additional liquid is continually replaced with an ultra-pure dialysate. Improved clinical outcomes with this form of this dialysis are long term (typically seen after more than two years). Longer hours on haemodialysis (as with home haemodialysis) can have the same positive effect.