What is dialysis access?
In the context of this article, dialysis access is an entranceway
into your bloodstream that lies completely beneath your skin and is
easy to use. The access is usually in your arm, but sometimes in the
leg, and allows blood to be removed and returned quickly, efficiently,
and safely during dialysis or, less commonly, for other procedures
requiring frequent access to your circulation.
Dialysis, also called hemodialysis, is the most common treatment for
kidney failure. A dialysis machine is an artificial kidney designed to
remove impurities from your blood. During dialysis, physicians use the
dialysis access to remove a portion of your blood to circulate it
through the dialysis machine so it can remove impurities and regulate
fluid and chemical balances. The purified blood is then returned to
you, again through the dialysis access.
Creating the access portal is a minor surgical procedure. There are two types of portals placed completely under the skin:
- Fistula, which your vascular surgeon constructs by joining an artery to a vein.
- Graft, which is a man-made tube, consisting of a plastic or
other material, that your vascular surgeon inserts under the skin to
connect an artery to a vein.
For
both fistulas and grafts, the connection between your artery and vein
increases blood flow through the vein. In response, your vein stretches
and becomes strengthened. This allows an even greater amount of blood
to pass through the vein and allows your dialysis to proceed
efficiently.In the weeks after surgery, the fistula begins to mature.
The vein increases in size and may look like a cord under your skin.
The whole process of maturation, which is a beneficial feature that
permits the blood flow to increase in the fistula, typically takes 3 to
6 months. Some fistulas may take as long as a year or more to develop
fully, but this is unusual. Once matured, a fistula should be large and
strong enough for dialysis technicians and nurses to insert the large
dialysis needles easily. If it fails to mature in a reasonable period
of time, however, you may need another fistula.
You can usually begin using your graft in 2 to 6 weeks, when it is
healed sufficiently. Usually fistulas are preferred to grafts, however,
because fistulas are constructed using your own tissue, which is more
durable and resistant to infection than are grafts. However, if your
vein is blocked or too small to use, the graft provides a good
alternative.
How do I prepare?
Before choosing the access site, your surgeon may ask you if you
have a history or symptoms of arm or leg artery disease. Hardening of
the arteries, which reduces blood flow to your arms or legs, often can
cause these conditions. Your vascular surgeon will not place a dialysis
access site in an area of the body with reduced circulation because the
blood flow will be insufficient. For this reason, your surgeon usually
places dialysis access sites in the arms rather than in the legs
because atherosclerosis is more common in the legs.
Your vascular surgeon may order a blood flow test in your arms and
legs, such as an ultrasound exam, or an x ray, such as a venogram, to
determine whether your veins are large enough to use for a fistula.
Sometimes a non-invasive pulse volume recording test is used to
evaluate the flow in your arteries if this issue is a concern to your
surgeon.
Your vascular surgeon will give you the necessary instructions you
need to follow before the surgery, such as fasting. Usually, your
physician will ask you not to eat or drink anything 8 hours before your
procedure. Your physician will discuss with you whether to reduce or
stop any medications that might increase your risk of bleeding or other
complications.
Am I eligible for dialysis access?
If you have chronic kidney failure and need long-term hemodialysis,
you may require dialysis access. You may not be a good candidate for a
fistula if your veins are too small or are scarred from frequent
placement of intravenous catheters (thin, flexible tubes inserted into
veins to deliver medicine) or needles to draw blood. In that event, you
may be eligible for a graft access procedure. You also may not be a
good candidate for a fistula if your arteries are severely blocked,
although they might be repairable if necessary. Your vascular surgeon
will probably be reluctant to use a graft if you have an ongoing
infection since the graft itself might become infected. If this
happens, the infected graft might need to be removed in order to clear
up the infection.
What happens during dialysis access?
Typically you will have the procedure on an outpatient basis. Most
often, you will first be sedated and then your surgeon will numb the
area where the fistula or graft will go. In some cases, your
anesthesiologist may give you supplemental sedation or put you to sleep.
Depending upon the quality of your artery and vein, your surgeon
will try to construct the fistula with one incision using the forearm
of the arm that you do not use as frequently. For example, if you're
left handed, your physician will place the fistula in your right arm,
if possible. To perform the surgery, your physician joins a large vein
under the skin to an artery nearby. The physician divides your vein and
sews it to an opening made in the side of the artery. As a result, the
blood flows down the arteries into the hand, as usual, and also some of
this faster moving blood flows into the veins that lead back to your
heart. The blood that normally traveled in your divided vein goes back
to the heart through other veins, and there is usually plenty of blood
remaining in your artery to supply your hand.
If you cannot receive a fistula because the vein is too small or
blocked, your physician may construct a graft using a tube of man-made,
plastic material. Less commonly, your physician may also choose to use
a piece of a vein from your leg or a section of artery from a cow as
alternative graft materials. Your physician sews the graft to one of
your veins and connects the other end to an artery. Your physician may
place the graft material straight or form a loop under the skin either
in your lower arm, upper arm, or less commonly in your leg.
What can I expect after dialysis access?
After the operation, you should initially keep the access area
raised above your heart to reduce swelling and pain. Your surgeon may
recommend an over-the-counter painkiller to relieve pain, if necessary.
Following the suggestions below will help you keep your new access site working properly in the weeks after the surgery:
- Keep the incision dry for at least 2 days after the procedure and do not soak or scrub the incision until it has healed.
- Avoid lifting more than about 15 pounds or other activities that stress or compress the access area, such as digging.
- Report pain, swelling, or bleeding immediately to your
physician, especially if these symptoms are becoming worse. Some pain
or swelling is common and not worrisome if decreasing, but you should
tell your physician if you have bleeding, drainage or a fever higher
than 101 degrees Fahrenheit
You may initially feel some coolness or numbness in the hand with
the fistula. These sensations usually go away in a few weeks as your
circulation compensates for the fistula. However, if these sensations
are severe or don’t disappear, tell your physician as soon as possible,
because the fistula may be causing too much blood to flow away from
your hand, a condition physicians call a “steal.”
You should perform exercises to grow and strengthen your fistula,
after the pain from the surgery decreases, to make dialysis faster and
easier. Your physician may recommend squeezing a soft object using the
hand on the arm in which the fistula was placed.
Grafts may mature more quickly than fistulas depending upon the size
of the vein to which the graft is initially attached. They sometimes
can be ready in 2 to 3 weeks, but many physicians recommend waiting
about 4 to 6 weeks before using a graft. Grafts have disadvantages over
fistulas, however. Grafts are more likely than fistulas to become
infected. Also, grafts usually last about 1 to 2 years, which is less
than fistulas, which can often last up to 3 to 7 years. If you care
properly for your graft, however, you can help it last for many years.
Sometimes access portals can take weeks or even months until they
are ready for dialysis use. Until the portal is ready, you may have to
use a catheter for dialysis.
Are there any complications?
Complications with dialysis access include, in addition to “steal”
discussed above, clotting, narrowing, aneurysm formation in the access
itself, infection, and bleeding.
What can I do to stay healthy?
Protecting the dialysis access is crucial for you. The following tips will help you care for a fistula or a graft:
- Check several times each day to make sure the access is
functioning. You should be able to feel a vibration in the fistula
called a “thrill”. Your physician or dialysis center staff will show
you how to do this.
- Monitor any bleeding after dialysis. If the graft seems to
bleed longer than usual from the needle sites, you should notify your
dialysis center staff.
- Do not carry heavy items with the arm that has the access.
- Do not sleep on that arm.
- Do not wear any clothing or jewelry that binds that arm.
- Do not let anyone draw blood or measure blood pressure from that arm.
- Do not allow injections to be given into the fistula or graft.
- Keep the site of the fistula or graft clean.
- After dialysis, monitor the access for signs of infection, such as swelling or redness.
- Do not use any creams and lotions over the site of the fistula or graft.