A structure that allows easy access into the bloodstream of a patient is referred to as Vascular Access. Haemodialysis is often essential for patients suffering from kidney failure and, therefore, access to the bloodstream is required for the purpose of haemodialysis. When performing haemodialysis, blood drawn out of the patient’s body is passed through a dialysis machine for removal of toxins. The toxin-free blood is returned to the patient’s body.
Vascular Accesses of three types are available for patients suffering from renal failure: catheter, arteriovenous fistula and arteriovenous graft.
Catheter: It is a temporary measure. It is used when some patients suddenly develop renal failure and require dialysis to be done urgently. Further, there will not be sufficient time to form an arteriovenous Graft and arteriovenous Fistula. It takes only half an hour to place the catheter and is used till a permanent access id created.
Arteriovenous Fistula (AVF): This access is surgically created connection between the surface vein of an arm and an artery. The pressure of blood in the artery is higher and this causes the vein to expand. When the size of the vein is suitable enough, it is used for haemodialysis. Generally, it takes around 6 weeks to 4 months for the vein size to increase and become suitable for dialysis.
In the case of some patients, the quality of the vein will be very poor and unsuitable for creation of an AVF. This calls for the placement of an artificial tube under the skin of the patient through a surgery. This tube connects an artery and a deep vein in the patient’s arm. The graft thus created is then cannulated for haemodialysis.
Typically, patients with end-stage kidney failure or those approaching the end stage are candidates for placement of vascular accesses. A patient is said to suffer from end-stage kidney failure when the condition of the patient’s kidneys have deteriorated so much that the kidney’s inability to remove water and toxins from the blood stream becomes a threat to his/her life.
Vascular access such as an AVF should be considered by patients who are moving into end-stage kidney failure. The AVF should be created in advance as it takes some time to settle down and becomes ready for use. Preferably, patients should have the AVF ready for use prior to starting of dialysis.
The patient is subjected to a careful examination and an ultrasound scan to ascertain the quality of the veins and arteries in the arms.
The AVF is created under local anaesthesia. This is done as Day Surgery by our vascular specialist. The procedure normally takes about 45 minutes, and patients are ready to go home shortly after surgery. Most patients do not feel any pain during the procedure. Even post-operative pain is minimal, with most patients taking pain-killers only for 1 day.
Local anaesthesia is often administered to create an AVF and it is done as a day surgery. To create an Arteriovenous Graft (AVG), generally regional anaesthesia is necessary. Local anaesthetic is administered below the collar bone and it blocks the sensory nerves that run down the arm to the forearm. The surgery is done after the arm becomes numb. It takes about two hours to place the AVG. Patients may develop slight swelling around the graft area after the surgery. It disappears in about two weeks.
The accesses do not have a long life. The AVFs last for a longer period of time than the AVGs. The main reason for the failure of the accesses is stenosis or narrowing at the access point. It is the scarring of the access’s inner lining that leads to narrowing.
The stenoses are treated by way of Angioplasty, if diagnosed early. It involves insertion of a balloon through the stenosis and inflating it to stretch the stenosis open. This helps to re-establish brisk flow of blood.
The limb on which the vascular access has been placed should be exercised on a regular basis. Any direct trauma to the access should be avoided. Further, the patient should get the blood flow through the access monitored every two months. It involves the measurement of the quantity of blood that flows through the access. Stenosis slows down blood flow. Regular monitoring enables us to determine if a stenosis occurs. If the blood flow reduces, patients are referred for angioplasty.