Vascular Access: FAQ
Q: What is dialysis access surgery?
Dialysis, either hemodialysis or peritoneal dialysis, is a life-saving procedure that replaces kidney function when the organs fail. In order to be treated with dialysis, physicians create a connection between the dialysis equipment and the patient's bloodstream.
Hemodialysis circulates blood through a machine outside of your body to remove toxins and excess fluid and to correct electrolytes such as potassium, sodium, phosphate and calcium. The machine then pumps the cleansed blood back into your body. Hemo-dialysis access can be established via several ways- arteriovenous fistula, graft or a catheter in a large vein. Your surgeon in collaboration with your nephrologist (kidney doctor) will work with you to decide which type of access will provide you with the best long-term dialysis.
Q: What is an AV fistula?
The best way to establish long-term hemodialysis access is to construct an arteriovenous (AV) fistula. A fistula is an opening or connection of two parts of the body. An AV fistula when placed by your surgeon connects an artery to a vein, usually in the forearm, to enable more blood to flow in the vein. The artery is a high-pressure vessel that carries blood away from the heart and delivers nutrients and oxygen to the tissues. The vein is a low-pressure vessel that returns blood back to the heart to begin the process all over again. When the artery and vein are sewn together, some of the high-pressure blood is diverted instead into the vein and back to the heart. Over time the vein will dilate, carry more blood and become thicker, allowing for maturation of the fistula vein. When the fistula is mature, nurses are able to access the vein with needles repeatedly for hemodialysis therapy.
Q: Where and how is the AV fistula procedure performed?
Your surgeon can create an AV fistula either in your wrist, forearm, or upper arm. When properly constructed, and with satisfactory maturation, an AV fistula can function for many years. The surgery to create the AV fistula is performed by your surgeon usually on an outpatient basis in the operating room. You receive a local anesthetic (numbing medicine) at the proposed site along with intravenous (IV) sedation to relax you. Discomfort is minimal and you may even fall asleep during the 1 to 2 hour-long procedures. The surgical incision is usually only 2 to 4 inches long. Generally you are able to return home later that same day. The fistula usually requires several months for it to develop properly so the veins to dilate prior to initial use. Other highlights of AV fistulas are: infections are rare, fewer complications occur with them and they can last many years, compared to weeks or months with other accesses.
Despite excellent technique, some patients may suffer complications from the AV fistula procedure. Infection, bleeding, arm swelling and/or tingling in the fingers may occur postoperatively. An unusual, but serious, complication can occur when too much of the arterial blood that is supposed to reach the hand is redirected through the fistula, causing the hand to become ischemic (lack of oxygen). This condition is called "steal" and usually requires surgical procedure to establish a new access at a different site and correct the problem. Finally a patient can experience clotting of his or her fistula, which may or may not be salvageable.
Q: Who can have an AV fistula?
Unfortunately not every patient is suitable for an AV fistula. Numerous needle sticks for IV fluids or medicine and/or blood work can sclerose (scar) and damage veins over time, which can make creation of an AV fistula impossible. If this occurs or the veins are too small, an AV fistula, if created, will not develop or mature, or may even clot off. In this situation, the transplant vascular access team will recommend other options that may include another fistula at a different site, catheter placement or an arteriovenous graft.
Q: What if one cannot have a fistula- what is an arteriovenous graft?
For patients with small veins that will not develop properly into a fistula, vascular access can be achieved through a synthetic tube that connects the artery to a vein. The tube, or graft, functions as an artificial vein that can be accessed frequently for needle placement during hemodialysis. Unlike the AV fistula, the arteriovenous graft may be used as soon as two to three weeks as it does not need to mature. Complications related to AV grafts are similar to those with AV fistulas: bleeding, thrombosis (clotting), steal and because of the prosthetic nature of the graft, infection. When a graft clots, interventional or surgical procedures can remove the clot and restore blood flow for dialysis. Infected grafts often need to be removed immediately and a new access site developed once the infection clears.
Q: How is the AV graft created?
In this procedure, surgeons connect an artery and a large vein in your elbow or armpit using a graft made of synthetic fabric that is woven to create a watertight tube. Small incisions may be made at the proposed site of insertion and surgeons sew the graft to an artery and tunnel it, just under the skin, creating a loop back to either the starting incision or another incision where it is then sewn to a vein. The long piece of graft gives the dialysis nurses space to access the graft .
Q: What if I have to start hemodialysis immediately - how are catheters placed?
If the kidney disease has progressed rapidly, patients may not have the luxury of time to allow for a permanent vascular access to develop for hemodialysis treatments. Hence a venous catheter, or tube with two chambers inserted into the neck, chest or leg, can be utilized as a temporary solution.
Catheters come in two varieties, temporary and permanent. Temporary catheters penetrate the skin and directly enter the venous system. Permanent catheters also penetrate the skin, but are then tunneled under the skin for several inches before they finally enter the venous system. Tunneling the catheter reduces the risk of infection.
Any medical professional can place a temporary catheter using a local anesthetic and minimal sedation to help with minor discomfort. However for placement of permanent catheters, a surgeon in the operating room, or an interventional radiologist in the interventional suite is necessary. During the procedure, physicians use fluoroscopy (continuous X-rays) to be sure the catheter is positioned correctly. Permanent catheters require a minor procedure for removal whereas temporary catheters can simply be pulled out.
Q: Can catheters be placed for long-term use?
A catheter will function for several weeks or months, while a permanent access develops. However, catheters are hardly ideal for permanent access as complications can occur. Infection is the most common complication. Even with excellent sterile technique, bacteria can enter the bloodstream through the catheter during dialysis. Bacteria from the skin can also move down along the catheter and enter the bloodstream. With catheter infection people develop fever and chills and need prompt treatment. Often, the catheter is removed so the body can fight the infection. Another possible complication from long-term catheter use is damage to the central veins, which can lead to stenosis (narrowing) or thrombosis (clotting) of the veins. This type of damage may become permanent and the vein, as well as the arm on that side, may no longer be useable for dialysis access. Therefore your physicians will make every effort to avoid prolonged catheter use, if possible.
Q: What if I do not want hemodialysis -how can I be surgically prepared for peritoneal dialysis?
A long silicone-based tube called a Tenckhoff catheter is placed into the abdomen prior to the initiation of peritoneal dialysis. The surgeon places the catheter in the operating room using either a local anesthetic and IV sedation, or general anesthesia if placing the tube laparoscopically. Regardless of approach, a small incision is made in your abdomen, and the surgeon places the tube deep into the lower part of your peritoneal cavity (the membrane lining the inside of the abdomen), and tunnels the tube under the skin for several inches, bringing the tube up through the skin at a different location, and then surgically closes the initial incision.
A sterile dressing covers the catheter that remains outside of the body. You will be allowed to go home the same day following surgery. Training for peritoneal dialysis begins when the incisions heal, usually about 2 weeks after the access surgery.
Q: What types of complications can be seen from peritoneal dialysis and a Tenckhoff catheter?
Complications are rare but can be related to catheter placement and may include bleeding, and rarely, damage to large or small intestines or abdominal blood vessels. If they occur surgery may be required. Complications related to catheter usage include peritonitis (an infection of the peritoneal cavity), which can be quite serious and is usually associated with abdominal pain, fevers and cloudy peritoneal dialysis solution. These infections, however, usually respond to antibiotic treatment. Rarely, the catheter may need to be taken out.
Q: When should I have any of these procedures for dialysis access surgery performed?
Depending upon the procedure dialysis access surgery might be done many months before dialysis therapy needs to begin. Thus allowing the access to mature and to avoid the use of temporary catheters. However at times, you may need a temporary catheter while you are waiting for your permanent AV fistula or AV graft to heal and mature.
Q: How do I care for my vascular access?
Patients should exercise their arm before and after surgery to encourage the fistula's development. The following techniques will assist in this process:
- Ball Squeeze: Once discomfort from surgery has subsided, patients may begin forearm exercises by squeezing a small rubber ball or rolled-up washcloth. Squeeze the ball and release it rapidly for 10 minutes, six times a day. You may use your other hand to squeeze the bicep of your fistula arm to prevent blood return.
- Bicep Curls: Holding a small weight or household can of vegetables in your fistula hand, curl your arm up and down slowly for 10 minutes, six times a day.
- Finger Tip Touches: You can strengthen your fistula by touching each finger to the top of your thumb, opening your hand up after each touch. Do this repeatedly for five minutes, six times a day.
Once your fistula has reached maturation, proactive measures should be taken to protect the access. These include:
- Keep your access clean at all times
- Only use your access site for dialysis
- Do not allow anyone to place a blood pressure cuff on your access arm
- Do not wear jewelry or tight clothes over your access site
- Make sure your nurse or technician checks your access before each treatment
- Do not lift heavy objects or put pressure on your access arm
- Check each day for the "thrill," or rhythmic vibration that can be felt over your fistula
- Be careful not to bump or cut your access
- Avoid sleeping with your access arm under your head or body