Apeksha Ekbote

Msc, RD

Chief Dietician, NephroPlus

A dialyzer is often referred to as an “artificial kidney.” Its function is to remove the excess wastes and fluid from the blood, when the patient’s kidneys can no longer perform that task. Dialyzers are made of a thin, fibrous material. The fibres form a semipermeable membrane, which allows smaller particles and liquids to pass through.

The dialyzer has four ports, one inlet, and one outlet port each for blood and dialysate. The semipermeable dialysis membrane separates the blood compartment and the dialysate compartment. The transport processes across the membrane are diffusion (dialysis) and convection (ultrafiltration). The removal of small solutes occurs primarily by diffusion; larger components, such as β2-microglobulin, are more effectively removed by convection.

There are majorly two types of Dialyzers – High Flux and Low Flux Dialyzers. The term ‘flux’ refers to the permeability of the membrane in the dialyzer (artificial kidney) across which accumulated toxins and excess fluid pass during hemodialysis. High flux membranes compared to low flux have larger pores and allow diffusion of greater amounts of uremic toxins and middle molecules such as β2 microglobulin and therefore they may decrease the risk of dialysis-related amyloidosis. However, Low flux dialyzers are an option for acute and chronic dialysis where a lower rate of fluid removal (e.g., ultrafiltration coefficient) is desired. However, there is another Medium cut-off (MCO) dialyzers which help remove larger middle molecules associated with symptoms related to the accumulation of uremic retention solutes. The medium cut-off (MCO) dialyzer has shown good clearance of large middle molecules, but its long-term effects are unclear.

A larger dialyzer with a larger membrane area (A) will usually remove more solutes than a smaller dialyzer, especially at high blood flow rates.

Hollow-fibre dialyzers are the most common dialyzers in use today. They are easy to use and provide low blood flow resistance, excellent mass transfer, low compliance, and controllable Ultrafiltration.

The dialyzer may either be discarded after each treatment or be reused. The basic procedure for dialyzer reprocessing involves four steps: rinsing, cleaning, performance testing, and disinfection and sterilization.

How many times can you safely reuse the dialyzer? There is no set number of times that is considered safe for dialyzer reuse. As long as the TCV test shows that the dialyzer is working well, and the dialyzer looks clean, it should be safe for you to reuse your dialyzer. However, there is no one best dialyzer that suits all. Consult your Nephrologist for the type of dialyzer that should suit your condition.