What is chronic kidney disease?
Our kidneys have two functions: cleanse the body of toxic substances produced by metabolism and regulate the amount of water and electrolytes in the blood. When the kidneys are unable to perform one of these functions, then the person suffers from chronic kidney failure. What actually happens is the accumulation of useless metabolic substances in the body. Patients with severe chronic renal failure undergo haemodialysis or kidney transplantation.
How does haemodialysis work?
When a patient is in the final stages of kidney failure their kidneys have undergone irreversible damage and cannot clear the blood; as a result this function is performed by the haemodialysis machine. Haemodialysis is a procedure performed three times a week. Two thin catheters connected to the machine are placed through puncture in two parts of the vessel; the first catheter directs the blood to be cleaned to the machine and the second directs the filtered blood back to the vessel.
Creation of vascular access – fistula or implant
For the execution of haemodialysis, easy access to the bloodstream through surgery is essential. The vascular surgeon selects a superficial vein, usually in the upper limbs and less frequently in the lower limbs, and creates large blood flow by connecting it to a nearby artery. This very arteriovenous communication is called fistula and allows blood to be removed from the body and go back safely, efficiently and quickly.
However, if the veins are very thin or narrowed due to venipunctures, then the doctor will proceed with the implantation of an artificial implant. One end is sutured to the artery and the other to the vein.
In both cases (fistula or implant), arteriovenous communication increases blood flow to the vein allowing a more effective haemodialysis. The vein of the patient with fistula gradually matures, hardens and becomes more visible due to its increased size. Within six weeks the vein is more durable, and the area is suitable for puncture. If it does not mature within three months, the operation may need to be repeated. The implant matures faster and can be punctured in about three weeks. The fistula is usually preferred because it is created by the tissues of the body itself, thus reducing the risk of infections. Needless to say, the implant is an optimum choice, especially in cases of narrowing or blockage of the vein.
What are haemodialysis catheters?
A permanent or temporary haemodialysis catheter is an alternative method of vascular access. Permanent central catheters are the only method of access to people with heart failure, the elderly, chronic diabetics, patients who will undergo immediate kidney transplantation, etc. They are usually placed in the anterior thoracic region and are connected to the internal jugular vein. The catheter is placed by the vascular surgeon under local anesthesia. Temporary catheters are used in cases where they are necessary for less than three weeks and when an infection or other access dysfunction develops.
Fistula: What is the procedure?
The operation is performed under local anesthesia and the doctor will prescribe antibiotic medicine to the patient to rule out infection. For the fistula procedure, the vascular surgeon makes an incision and connects the vein to the artery. However, when an implant is used, two incisions are made under the surface of the skin, to place the implant and connect it at one end to the vein and at the other to the artery. The operation takes about 90 minutes. In right-handed patients the surgery is performed on the left hand while in left-handed on the right.
Fistula: How is the access location selected?
The access location depends on the patient’s history; for example, if a person suffers from atherosclerosis, the blood flow towards the upper and lower limbs is reduced, so the area is not suitable for arteriovenous communication. That is why some tests are required, such as triplex and angiography and depending on the results, the doctor will determine if the artery is suitable, if the arterial circulation is normal, if there is a narrowing, etc.
What precautions should be taken after surgery?
Once the operation is completed, the doctor will ask the patient to hold their hand high (approximately at the height of the heart) to reduce the chances of swelling or pain. If the patient is in pain, painkillers will be administered. It is very natural for a person to feel their arm slightly numb in the first few weeks after surgery but gradually the sense of the limb will return. Both fistula and implant need a few weeks to be used for haemodialysis. A haemodialysis catheter may be used during this time.
The doctor will advise the patient to:
• avoid weight lifting and other activities that could damage the fistula
• avoid the contact with water as the incision should not get wet until the removal of the sutures
• contact the doctor in case they feel pain, swelling or bleeding in the incision area or have high temperature, particularly if the symptoms worsen
• avoid wearing clothes that put pressure on the area
• avoid to draw blood or take blood pressure from this hand
• avoid sleeping on the side where the operation was performed.
Can there be complications from vascular access – fistula?
Complications that could occur are aneurysm formation, infection, bleeding, narrowing of access due to blood clots, neuropathy, etc.