A vascular access is required to perform any type of hemodialysis treatment, and it provides an entryway into your bloodstream. It is frequently referred to as your “lifeline”, because a functioning access is required for your survival. It is essential for you to properly care for your access, so it lasts and works properly.
Hemodialysis Vascular Access
Before beginning regular hemodialysis treatments, it is important to prepare a vascular access site. Ideally, the vascular access should be placed weeks or months before starting dialysis, so the access has sufficient time to heal and mature. The dialysis access allows about a cup of blood at a time to be removed from your body for cleaning. The blood then goes through an artificial kidney, or dialyzer, to remove fluid and waste products before it is returned to the body. To maximize the amount of blood cleansed during dialysis, blood needs to flow at a relatively high rate. The three basic types of vascular accesses for hemodialysis are an arteriovenous (AV) fistula, an arteriovenous (AV) graft and a central venous catheter (CVC).
A fistula requires a month or more to mature and heal, so surgery should be planned in advance of starting hemodialysis. A surgeon creates an AV fistula by connecting an artery directly to a vein. The high blood flow from the artery through the vein allows the access to grow larger and stronger. Small vessels or other medical conditions may make it difficult for some people to have a successful fistula. The preferred initial access site is in the wrist or forearm of the non-dominant arm. You should feel a buzzing vibration or pulse as blood flows through your access. The vibration is called the thrill. Your caregivers will also listen for the blood flowing through your access with a stethoscope.
The sound heard through the stethoscope is called a bruit (brew-ee). Your caregivers will help you become familiar with how to check your access to make sure it is working properly. The most common problem with the AV fistula is a narrowing of the blood vessel, called a stenosis, which may lead to decreased blood flow or clotting in the access. A properly constructed fistula is the least problematic of any dialysis vascular access. It is less likely to form clots or become infected, and it lasts longer than grafts or catheters.
A graft may be placed if you have small or weak veins that won’t allow proper fistula development. A graft connects an artery to a vein using a synthetic tube implanted under the skin. Blood flows through the graft. Grafts are ready to use relatively quickly. A graft can typically be used within two to four weeks after placement. Like a fistula, a graft has a thrill you can feel, and a bruit you can hear with a stethoscope if the access is functioning properly. Compared to fistulas, grafts tend to have more problems with clotting and infection and need replacement sooner, although well cared for grafts can last a number of years.
Caring for an AV Fistula Graft
Here are a few things to remember when caring for your vascular access:
A catheter is a flexible, hollow tube inserted into a large vein in your body. It allows the blood to flow in and out of your bloodstream. There are several places where catheters may be placed. The most common sites are:
Catheters can usually be used right after they are placed, but they do not typically allow for high blood flow rates, resulting in a less efficient treatment. Catheters have two chambers. One allows blood to flow out of the bloodstream to be cleaned, and the other allows cleansed blood to return to the body. Some catheters have stitches to help hold them in place. Cuffed catheters tunnel under the skin and have a small bump (cuff) near the exit site. The cuff should remain under the skin to hold the catheter in place and prevent infection. The catheter exit site, where the catheter comes out of the skin, should be covered by a dressing.
Catheters can clot, cause veins in which they are placed to narrow (stenosis) and become infected. Catheter dressings should be changed frequently and always kept clean and dry to help prevent access site infections from occurring.
Problems with vascular accesses can still occur even with proper care, but they can usually be corrected when identified early. Your health care team will work with you to monitor your access regularly and help you keep your access healthy and working properly.