There are three types of vascular accesses for hemodialysis:  an arteriovenous fistula (AVF), an arteriovenous graft (AVG), and a central venous catheter.  An AVF provides a direct connection between the artery and the vein allowing the vein to dilate and thicken so that it may be accessed repeatedly for hemodialysis. The AVF is generally accepted as the preferred method for long-term  dialysis access as it provides excellent blood flow for dialysis, has the best longevity, and has a complication rate lower than the other access types.  If an AVF cannot be created, an AVG or venous catheter may be needed.

Any type of dialysis access requires advanced planning as a fistula can require weeks or months to develop to a point where it can be used for hemodialysis.  This should be  preceded by a duplex ultrasound examination (vein mapping) to determine which veins are patent, the diameter of these veins and the quality of the veins in the arm. Additionally, arterial inflow can be assessed to insure adequate flow to the access and to the hand.

An AVF is created on an outpatient basis.  Patients are usually administered a local anesthetic with intravenous sedation.  General anesthesia can be avoided. Patients can expect some mild swelling and discomfort at the site.  Frequent post-operative checks are important to ascertain when the fistula is “mature”—or ready to  be accessed.  It is common for the AVF to be used with one needle initially adding the second needle after 2-3 successful cannulations with one needle.

An alternative to the AVF is an Arteriovenous Graft (AVG).  If a patient has veins that are likely not to sustain  a fistula, a vascular access that uses a synthetic tube implanted under the skin can be placed.  The tube serves just as a vein would and can be used for access during hemodialysis.  A graft does not require the same maturation time  as a fistula , and, thus,  can be used sooner after placement--usually within two weeks.  Grafts tend to have more prone to thrombosis and infection than AVFs but a well placed AVG can serve a patient well for several years.

The third  option for dialysis access is a Central Venous Catheter (CVC.)  If the patient’s kidney disease has progressed quickly, time may not allow for placement of an AVF or AVG prior to initiating hemodialysis treatments.  Instead, they may need to use a venous catheter as a temporary (bridge) access until an alternative is available.  The goal is to avoid use of catheters when possible but CVCs do serve a very useful function.

A catheter is a tube that has two lumens (one to remove blood from the body and the other to return it) inserted into a central vein (preferably the internal jugular vein but, on rare occasions, the subclavian vein.)  Catheters are not ideal for permanent access as they can occlude, become infected, or cause narrowing of the veins in which they are placed.  However, if a patient needs to begin hemodialysis immediately, a catheter will suffice for several weeks or months while their permanent access develops.

For some patients, when a fistula or graft surgery is not successful, a long-term catheter access must be used.  Catheters that will be needed for more than 3 weeks are designed to be tunneled under the skin to increase comfort and reduce complications.

With every hemodialysis session, needle insertion is required.  Two needles are used – one to provide blood to the dialyzer and one to return the cleaned blood to the body.  Some patients prefer to insert their own needles.  Patients will need training for this to learn how to prevent infection and protect their vascular access.  Whether a patient inserts their own needles or not, they should know about these techniques to further understand and ask questions about their treatments.

All three types of vascular access – AVF, AVG, and CVC--can have complications that require surgical treatment.  The most common complication is access infection followed by inadequate blood flow to allow for effective hemodialysis. 
When accesses develop poor flow, intervention is necessary.  Accesses with poor flow do not allow for effective hemodialysis.  In these circumstances, the access may require a fistulogram or duplex scan  to identify the problem causing the low flow.  Depending on the findings during the diagnostic procedure, an intervention (angioplasty or revision) may be required to restore proper function of the access.

A patient can do several things to protect their access:

• Make sure their nurse or technician checks their access before each treatment
• Keep their access clean at all times
• Use the access site only for dialysis
• Do not allow blood draws or insertion of an IV line in their access arm
• Do not wear jewelry or tight clothes over their access site
• Do not sleep with their access arm under their head or body
• Check the pulse in their access every day.