Hemodialysis is the most common way to treat advanced kidney failure. In hemodialysis, a machine filters wastes, salts and fluid from your blood when your kidneys are no longer healthy enough to do this work adequately.
The procedure can help you carry on an active life despite failing kidneys. For hemodialysis, you are connected to a filter (dialyzer) by tubes attached to your blood vessels.
Your blood is slowly pumped from your body into the dialyzer, it is filtered and then pumped back into your body.
Hemodialysis may improve your quality of life and increase your life expectancy, however it does not reverse chronic kidney failure.
Hemodialysis treatment usually lasts about four hours and is done three times per week. There are different types of hemodialysis that can suit your lifestyle and underlying medical conditions:
- In-center hemodialysis: Get treatments at a dialysis center from caring kidney care professionals and interact with other patients.
- Home hemodialysis: Perform hemodialysis in the privacy of your own home, with a trained care partner to help you with treatments.
- Nocturnal hemodialysis in-center or at home: Turn sleep time into dialysis treatment time. Hemodialysis is done 3 to 7 nights a week. Each session is done overnight (about 6 to 8 hours).
Before dialysis treatment can begin, your vascular surgeon will need to create a site where the blood can flow in and out of your body during the dialysis sessions.
This is called a dialysis access. Your vascular surgeon will perform an extensive physical exam to identify satisfactory vessels to construct the fistula or implant a graft.
He or she will then perform (or request) an ultrasound study for “vein mapping” of your arms or even legs looking to identify the best available (if any) vein for fistula planning.
The typical site to get your first access is the wrist or forearm of your non dominant hand.
If these sites are not suitable or have already been used, then your vascular surgeon may choose to use the wrist or forearm of the dominant hand before eventually using the upper arm or even your groin’s veins.
Arteriovenous Fistula:
The best way to establish long-term hemodialysis access is to construct an arteriovenous (AV) fistula. An AV fistula is created by directly connecting an artery and vein (usually in the wrist, forearm or arm).
The artery is a high pressure and flow thick blood vessel directing blood to the hand.
The vein is a low pressure and flow thin blood vessel returning blood back to the heart. By surgically connecting the artery to the vein, the high pressure arterial flow is diverted towards the vein which will gradually grow bigger to accommodate these higher flows.
This process is called vein or fistula maturation. You will be taught to do exercises, such as squeezing a rubber ball, to help the fistula mature faster.
This takes six weeks to four months. Once the fistula has matured, it is usually dilated, well visible and a strong “buzz” can be felt on top of it.
This is a good sign. It is then ready to allow easy access with the needles that will be introduced to circulate and filter your blood through the dialyzer.
The benefits of a fistula compared to other access types include:
- lower risk of infections
- lower risk of clots and subsequent re-interventions
- performs better allowing higher blood flows
- lasts longer, sometimes even for decades if well-cared for
Some of the drawbacks include:
- the appearance of bulging veins at the access site
- need to wait for months for a new one to mature
- possibility to never not mature
Fistula creation is a minor surgical procedure that may be performed as an outpatient operation using a local anesthetic and some twilight sedation to relax you.
The surgical incision is usually only 3-6cm long. Your vascular surgeon carefully dissects and identifies your vein and artery and connects them doing a hand-sewn anastomosis (blood vessel connection).
A few stiches are then placed to close the skin. The operation lasts 1-2 hours and generally you are able to return home later that same day.
Still, as all procedures, creation of a fistula may be associated to some complications, fortunately rare: infection, bleeding, arm swelling and/or tingling in the fingers may occur postoperatively.
Another unusual, but serious, complication may occur when the arterial flow that is diverted (“stolen”) through the fistula is that much that not enough blood reaches the hand resulting in pain and gradual loss of sensation and motor function.
This condition is called "steal syndrome" and usually requires either the fistula to be sacrificed, or another major surgical procedure to restore blood flow to the hand.
Steal syndrome occurrence is unpredictable, but it will occur more frequently in patients with small calcified (atherosclerotic) arteries and particularly in diabetics. You will need to discuss all these with your vascular surgeon.
Unfortunately not everyone may be able to have a fistula due to various conditions.
Numerous needle sticks for blood work or IVs for fluids and medicines can damage veins over time, creating scar tissue, which can make creation of a fistula impossible.
If the veins have been used for prior fistulas or are damaged or too small, the new fistula will not mature, or worse yet, clot. In this situation, your vascular surgeon will recommend other options that may include an arteriovenous “plastic” graft or catheter placement.
Arteriovenous Graft:
If your veins are too small or scarred, they are not adequate for a fistula. In this case the doctor may use a soft plastic tube to join an artery and a vein under your skin.
This is called an arteriovenous (AV) graft.
The AV graft is similar to a fistula, in that it connects the artery and vein under the skin, except that a plastic tube (graft) is interposed between the artery and vein.
It’s about 6mm in diameter and is made from a type of Teflon or Gore-Tex (PTFE) material.
Specially processed animal or human vessels may also be used as grafts.
They’re usually placed in the forearm or arm, but can also be placed in the thigh.
They are usually placed in a loop configuration that will facilitate needle access.
A graft does not need to develop as a fistula does, so a graft can be used usually within 2-4 weeks. Some grafts can be used as soon as 1 day after placement (immediate access grafts).
In general grafts do not perform as well as fistulas; that is why they are always a second option. However, many times they may serve a patient’s needs better, particularly when multiple fistulas are failing.
Grafts have a lifespan of approximately 2 to 3 years but can often last longer. Forearm loop grafts can eventually help the arm veins grow large enough (mature), so that when the graft goes down, a fistula creation may be feasible.
The main drawbacks of a graft include the high infection risk and the higher risk of clots and subsequent re-interventions.
Graft placement is a minor to moderate risk surgical procedure that may be performed as an outpatient operation using a local anesthetic and twilight sedation to relax you.
Your vascular surgeon will make one or two small incisions at the proposed access site and will identify the vein and the artery.
The graft is then sewn to the artery and tunneled just under the skin, creating a loop and then sewn to a vein.
A few stiches are then placed to close the skin.
The operation lasts 1-3 hours and generally you are able to return home later that same day. At completion a weak “buzz” can be felt on top of the graft.
This is a good sign that the graft is functioning well diverting blood flow from the artery into the vein.
Complications related to AV grafts are similar to those with AV fistulas: bleeding, thrombosis (clotting), steal syndrome (see section “Fistula”) and because of the prosthetic nature of the graft, infection.
Infected grafts must be removed immediately and a new access site developed once the infection clears. Whenever a graft clots, a minor surgical procedure can be done to remove the clot and restore blood flow for dialysis.
This clot removal (graft “thrombectomy”) can be done multiple times before your vascular surgeon decides to abandon this access and plan for a new one.
Catheter:
Occasionally, an access is made by means of a narrow plastic tube, called a catheter, which is inserted into a large vein in your neck or groin (rarely can be placed through your right upper side of your abdomen or through your lower back).
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.
Catheters are the least favorable option for hemodialysis as they are associated to a high complication rate including infection and damage of the central veins they’re going through.
This damage (vein clotting and scarring) may be that bad that any future attempt for a fistula or graft placement may fail.
It has also been shown that long term use of catheter decreases patients’ life expectancy. Because of these potential complications, physicians make every effort to avoid prolonged catheter use.
Their only advantage is that they can provide immediate access for dialysis, as they can be placed within a few minutes with a simple procedure.
They will usually serve as a bridge till you obtain a functional fistula or a graft.
They may otherwise be the only option for patients who have exhausted all other dialysis alternatives.
Any medical professional can place a temporary catheter at the bedside using a local anesthetic.
After sterilizing the access site, under ultrasound guidance your doctor will puncture the target neck or groin vein and introduce the catheter.
Placement of permanent catheters is preferably done by a vascular surgeon in the operating room with minimal (if any) sedation for any minor discomfort as it also involved tunneling of the catheter under the skin. During the procedure, x-rays will be used to confirm the correct positioning of the catheter.