Vascular Access for Hemodialysis
Kidneys filter the extra waste and fluids from the blood, and when they stop working, dialysis may be needed. One common form of dialysis is hemodialysis. In hemodialysis, your blood from your arm will flow through a thin plastic tube called a dialyzer that is hooked up to a machine. This machine filters your blood and works like your kidney. The dialyzer removes the extra fluids and waste from your blood and then the clean blood flows out of the machine and through another tube that is placed in a vein in the same arm. The sessions last for three to four hours and are needed at least three times a week.
In order to maximize the amount of blood cleansed during a session, you should have a vascular access. This is a site on your body where blood is removed and returned during hemodialysis. The vascular access allows for continuous blood flow in high volumes.
A vascular access point should be prepared at least a few weeks or months before dialysis starts. Additionally, the early preparation allows for easier and more efficient hemodialysis with less complications.
There are three kinds of vascular access for hemodialysis. They are an arteriovenous (AV) fistula, an AV graft and a venous catheter.
A fistula is an opening that connects two body parts that are generally separate. An AV fistula causes the vein to grow larger and stronger for easier access to the blood stream. This is often considered the best long-term vascular access for hemodialysis because it is durable, provides adequate blood flow and has a lower complication rate than other access procedures.
This process requires advance planning since fistulas take time after surgery to form - maybe even as long as 24 months. However, properly formed fistulas can last many years, much longer than any other kinds of vascular accesses.
You will be given a local anesthetic and the procedure may be performed as an outpatient basis. A surgeon will create an AV fistula by connecting an artery directly to a vein. This allows for more blood flow into the vein and usually occurs in the forearm.
When a small vein will not develop properly into a fistula, an arteriovenous graft is a second option. This vascular access connects an artery to a vein using a synthetic tube or graft and is implanted under your skin. The graft acts as an artificial vein that can be used frequently for needle placement and blood access during hemodialysis. The graft or synthetic tube can be used two to three weeks after surgery.
Grafts often have more problems with clotting and infection. They will need replacement sooner. However, a graft that is monitored closely can last many years.
If your kidney disease progresses quickly, you may need to use a venous catheter as a temporary access point for hemodialysis treatments.
A catheter is a tube that can be inserted into a vein in your neck, chest or leg near the groin. The venous catheter has two chambers to allow for the blood to flow two ways.
Unlike AV fistulas, catheters are not ideal for permanent access. They can cause the veins to narrow, clog or even become infected. However, a catheter can be extremely useful immediately and will work for several weeks or months while a permanent vascular access develops.