In patients with kidney failure, the kidneys become unable to effectively remove toxins, excess fluid, and electrolytes such as potassium. The build up of these compounds in the bloodstream can become a life threatening problem. Dialysis is a filtering process where these toxic substances or excess fluids are removed from the body. There are two types of dialysis: peritoneal and hemodialysis.
Peritoneal dialysis (PD) uses a patient’s abdominal cavity in conjunction with specialized dialysis fluid as the filtering system that allows for the elimination of toxins. In order to add and remove the dialysis fluid, a special tube (or catheter) is surgically inserted into the abdominal cavity. The dialysis solution draws fluids, electrolytes, and toxins out of the bloodstream through the abdominal wall membrane and into the space around the abdominal organs. The fluid remains in the abdomen for 4 to 6 hours before it is drained out of the catheter. The principle advantage of PD is that it can be done at home and no external machines are required for the process.
Hemodialysis (HD) is a system where the patient is hooked up to a specialized external filter/pump system that filters excess fluid, toxins, and electrolytes directly from the bloodstream. For this to occur there must be a way to directly access the patient’s bloodstream. This can be done via an indwelling catheter (tube) placed in a large central vein, or by surgically connecting an artery to a vein via a graft or the creation of an arteriovenous (AV) fistula.
Indwelling catheters are typically used as a temporary measure. The catheter is commonly placed in the internal jugular vein of subclavian vein in the chest. The catheter is tunneled under the skin and there are two ports which are visible from the outside. The disadvantages of these catheters are that they are susceptible to infection and they can become a stimulus for clots to form in the veins. The principle advantage is the catheter can be used immediately and they are a bridge for dialysis until the fistula or graft is ready for use. In some patients, with no suitable veins for creation of an AV graft or fistula, catheters may be used long term.
For optimal dialysis, there must be a reliable way to get a high flow, high pressure stream of blood to the dialysis machine. While arteries are high pressure and high flow, they reside deep in the body and are not expendable structures. Veins on the other hand are easy to get to and expendable but they are low pressure and low flow. The concept of arteriovenous access is to surgically create a way to turn a vein into an artery like structure. An AV fistula is a technique in which a suitable vein is connected directly to an artery. This is most frequently performed in the non-dominant arm or forearm. Connecting the vein to the artery leads to increased blood flow into the vein and as a result the vein grows larger and stronger. This provides the high flows needed for hemodialysis. Once a fistula is created, the maturation process usually takes about 8 weeks before it is suitable for use.
An AV graft may be recommended instead of a fistula if the superficial veins are too small. In this situation an artificial graft or tube is used to connect the artery to the vein. The graft is tunneled under the skin and therefore nothing is exposed to the outside. The graft material itself is directly punctured for hemodialysis access. The graft is usually suitable for use approximately two weeks after its placement. Compared to a fistula, the graft has a higher rate for infection and clotting.
The Surgeons at EvergreenHealth Heart & Vascular Care are highly skilled in all modalities of dialysis access. PD catheters are placed laparoscopically in order to assure accurate placement. Hemodialysis access will be tailored to your needs and once access is placed, we will continue following you and working with your nephrologist to care for your fistula or graft. Our vascular lab will be able to provide an accurate assessment of your graft or fistula problems. Dialysis can be a difficult lifestyle transition and our staff is committed to creating and maintaining your dialysis lifeline.