What is Haemodialysis?

Firstly, a vascular access that allows a large volume of blood to flow to the dialyser or filter is required. The access could be an arteriovenous fistula (AVF) or a vascular access catheter. 

Veins cannot be used in haemodialysis because they are too narrow and do not produce a sufficiently high flow rate. An arteriovenous fistula is therefore created through a surgical intervention that joins an artery to a nearby vein; this is typically carried out under local anaesthesia and on an outpatient basis. The vein increases its diameter in order to accept the higher pressure blood flowing into it from the artery, thus we obtain a sufficient flow rate for dialysis. Four to six weeks after creating the fistula, the vein will be wide enough to accept the repeated punctures carried out during haemodialysis sessions. 

The artery and vein are sometimes connected by implanting a small prosthesis, known as a prosthetic arteriovenous fistula. 

A vascular access catheter consists of placing a tube in one of the body’s large veins found in the neck or thigh. Catheters are normally used as temporary accesses because they involve the risk of infection; however, they may be used permanently when an arteriovenous fistula cannot be created. As with fistulas, they are usually performed under local anaesthesia and do not require a hospital stay.  

Patients must receive 3 sessions of haemodialysis per week, on alternate days, and each session lasts 4–5 hours. The frequency or length of sessions may need to be increased in certain cases.

The treatment may be performed in a specialised dialysis centre (outpatient haemodialysis) or at the patient’s home (home haemodialysis).

The advantages of home haemodialysis are that patients do not have to travel to hospital and it offers greater scheduling flexibility. However, both the patient and their carer need to spend 2 or 3 months learning how to perform dialysis before starting the sessions.