For this type of treatment, the patient’s blood flows through an artificial kidney to be filtrated. To make this possible, the patient has to undergo an operation to form a fistula into which needles can be inserted.
The needles are then attached to bloodlines, which flow through the artificial kidney. This artificial kidney is a bundle of hollow fibres with a semi-permeable membrane.
The membrane is a thin film with thousands of microscopic holes. The holes allow water and other small dissolved parts through but prevent the transfer of larger elements such as proteins and blood cells.
During dialysis, the blood flows on one side of the membrane and an electrolyte solution on the other end of the membrane. Through osmosis and diffusion and exchange of waste products takes place between the two liquids. A dialysis machine and artificial kidney are used in the process.
The whole process is monitored and controlled by the dialysis machine and the technician. The apparatus controls the movements of the blood through the artificial kidney and back to the patient as well as the mixture of the electrolyte solution. Each dialysis session takes approximately 4 hours to complete.
Advantages of Hemodyalisis
- Trained personnel do dialysis
- No equipment at home
- Treatment 3 times a week
- No external access site
- You have constant contact with the dialysis personnel and other patients.
Disadvantages of Hemodyalisis
- Transport to the dialysis centre
- Set times for dialysis treatments
- Two needles are inserted with each treatment
Access for Hemodialysis to take place
The most common access areas now used are:
- Arterio-venous (AV) fistula
- Arterio-venous (AV) graft and a permanent catheter.
Temporary catheters are sometimes used at the beginning of dialysis until permanent access can be established.
Your doctor surgically constructs the fistula by directly combining an artery and a vein in the forearm. Due to the arterial pressure, the vein will increasingly become thicker. It takes the fistula 4-8 weeks to ripen before needles can be inserted. A fistula is needed for two needles to be inserted and be connected to the dialysis machine through particular bloodlines.
A Graft is a synthetic blood vessel that combines an artery and a vein. This is used when the patient’s blood vessels are too small for the construction of a fistula. The shape of a graft can be oblong or loop-shaped and is positioned just below the skin. A graft can be of a synthetic material or taken from the patient’s body, e.g. an artery from the upper thigh.
Caring for your Fistula or Graft
Keep the area clean and dry Feel for a brewing sensation on both sides of the fistula/graft daily Inspect the fistula/graft for swelling, tenderness, redness or warmth to the touch — this can indicate infection.
Avoid tight-fitting clothing or jewellery that can constrict so block the fistula/graft the fistula/graft arm must not be used for monitoring of blood pressure, drawing blood or any intravenous administration Avoid pressure on the fistula/graft after dialysis Rotate the needle’s point of entry to avoid aneurysms.
In the case of injury to the fistula/graft, apply pressure on the area and get immediate medical attention. Wear a ‘medic-alert’ bracelet to indicate that you are a dialysis patient.
Patients who have problems with the fistula or graft use permanent catheters. Temporary access is obtained using a special catheter if the patient has to start immediately with dialysis cannot wait for the fistula to ripen. This catheter cannot be utilised for an extended period because it can cause blockage and because of the risk of infections.