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A Vascular Access is a structure that allows easy access to a person’s bloodstream. Patients who have renal failure frequently require haemodialysis. In order to perform haemodialysis, access to the patient’s bloodstream is necessary. This is because blood is taken out of the body, placed into the dialysis machine where toxins are removed and then subsequently returned back into the body.
There are 3 types of Vascular Accesses for patients with renal failure:
The catheter is temporary. It is used because some patients develop renal failure suddenly, and need dialysis very urgently. In such situations, there is no time to create an Arteriovenous Fistula or Arteriovenous Graft. The placement of the catheter can be done within half an hour. It is kept in place until a more permanent access such as the Arteriovenous Fistula or Graft has been created.
An Arteriovenous Fistula (AVF) is the surgical connection of an arm surface vein to an artery. The high pressure blood flow in the artery will cause the vein to expand in size. When it reaches a suitable size, it can be used for haemodialysis. It usually requires between 6 weeks and 4 months to reach a suitable size for dialysis.
Some patients have very poor quality veins that are unsuitable for AVF creation. In such patients, an artificial tube is surgically under the skin connecting an artery to a deep vein of the arm. This graft is then cannulated for dialysis.
Patients with kidney failure that is end-stage or is approaching end-stage. End-stage kidney failure is when the kidneys have deteriorated to the extent that their inability to remove toxins and excess water from the bloodstream becomes a threat to life.
Patients who are approaching end-stage kidney failure should consider having a vascular access such as an Arteriovenous Fistula created even before they reach end-stage. This is because the vascular access takes some time before it can be used, and it is preferable to have one ready for use when the time to start dialysis comes.
The patient will be examined carefully. An ultrasound scan will be performed to assess the quality of the arteries and the veins in the patient’s arms.
The AVF is created under local anaesthesia. This is done as Day Surgery. 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.
The Arteriovenous Graft (AVG) usually requires regional anaesthesia. This is where a local anaesthetic is injected under the collar bone to block the sensory nerves supplying the arm and forearm. Once the arm and forearm are numb, the surgery is carried out. AVG placement normally takes about 2 hours. There is usually some swelling around the graft after surgery which takes about 2 weeks to settle.
The main problems with accesses is that they do not last forever. AVFs have a longer average lifespan compared to AVGs. The main cause of failure of these accesses is narrowing, or stenoses, within the lumen of the access. The narrowing is caused by scarring of the inner lining of the access.
Fortunately if diagnosed early, these stenoses can be treated with angioplasty, which is a procedure where a balloon is inserted through the stenosis. The balloon is inflated stretching the stenosis open hence re-establishing smooth and brisk blood flow.
Exercise the limb with the access regularly.
Avoid direct trauma to the access
Undergo flow monitoring. Flow monitoring is where the rate of blood flowing through the access is measured. A narrowing (stenosis) in the access would slow the flow. If monitored regularly, we would know a stenosis is developing when we notice the flow rate starting to drop. Patients with a drop in their flow rate are referred for angioplasty of their vascular access. Flow monitoring should be performed every two months.
The Vascular & General Surgery Centre
Unit 18-05, Paragon Medical Suites, 290 Orchard Road, Singapore 238859
Tel: +65 6736 2302
Fax: +65 6736 4186
Whatsapp : +65 8866 7837
Email: enquiry@tvgsc.sg
24-hour Answering Service : +65 6535 8833
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