What is an arteriovenous fistula (AVF)?
An AVF is a direct communication between an artery and a vein. It is considered as an abnormality when it happens spontaneously in the body. But for purposes of haemodialysis, this communication is deliberately performed as a surgery.
Why is it done?
During haemodialysis, blood is drawn out of the body, cleaned in the artificial kidney (dialysis machine) and returned to the body. This amount of blood is fairly large quantity (around 200ml per minute), and will not be able to flow in a normal blood vessel. By creating this short circuit, more arterial blood will flow in the vein and allow the vein to increase in size. It then becomes easy to puncture this vessel for purposes of a haemodialysis.
In which part of the body is it done? Is it seen?
The joining of the blood vessels is done under the skin. Usually it is a small scar of about 3 to 4cm. No tubes or needles are visible on the outside. It is usually performed in the non-dominant arm of the patient either at the wrist or elbow. Once the wound heals, only a thin scar remains on the skin. Nothing else is visible outside.
Is it a simple procedure?
Yes. It is usually done under local anesthesia, and takes around one hour to perform. Only in cases of difficulty, does it take longer. If the blood vessels for any reason are not suitable at the distal part of the forearm or at the wrist, other sites may also be selected, like the elbow, the upper forearm, or the upper arm.
Do I need to stay in the hospital?
The AVF procedure itself requires no admission. Associated medical conditions may indicate the need for hospitalization. Sometimes if the blood flow following the procedure is not good, heparinisation may require hospital stay. Otherwise the patient will be sent home after a few hours.
What medications do I need to take after the procedure?
Generally a simple antibiotic is prescribed for five days. Other than that, medications prescribed for chronic renal failure itself will need to be continued. Suitable pain-killers may also be required.
When do I visit the doctor after the procedure?
The first visit is scheduled ten days after surgery. The wound will be inspected and appropriate instructions given. Sutures are generally removed only after the tenth day.
What precautions do I need to take, once the fistula is performed on my arm?
Never wear anything tight around the fistula arm, because the blood flow may be blocked. Blood pressure should not be checked on the same arm. Similarly no laboratory investigations involving drawing of blood should be done from the same arm. Intramuscular and intravenous injections are also to be avoided on the same arm. Avoid sleeping on the arm, you can do all your routine work.
When can the fistula be used for haemodialysis?
A new fistula takes about 3 to 4 weeks to mature before it can be used for haemodialysis. To facilitate blood flow across the fistula, hand exercises, which increase the muscle activity in that arm, will be taught.
Does the procedure always work?
Most of the time yes. Occasionally if there are very small veins, diabetic changes in the blood vessel, previous injections or intra venous treatment may come in the way of a successful surgery. You will then need a new fistula to be created at a different site.
How long does an AV fistula work?
If maintained well, it can work for a lifetime. This depends upon the quality of the blood vessel, episodes of low blood pressure, infection etc., which can cut short its functioning.
Will there be any complication in using the veins in the forearm for Haemodialysis?
Yes. Some times bleeding and haematoma can occur at the site of the puncture; rarely, infections can also occur.
If there is a bleed from the AV Fistula site, what should I do?
Immediate compression on the bleeding area, maintained by either a thumb pressure or a tight bandage around the bleeding site is necessary. Pressure anywhere else will only serve to increase bleeding from the fistula site.
Always contact your doctor if you think there is abnormal swelling or sensation at the site of the fistula.
Sudden bleeding can be life threatening, and must therefore not be neglected.
Are there any precautions to be taken prior to the performing of a fistula ?
Once diagnosed to be having kidney failure, it is important to preserve the non-dominant upper limb so as to make it available for the procedure at a later date. Avoid taking any injections or giving blood samples for laboratory investigations from this upper limb
Educational material published as part of community service by:
DEPARTMENT OF UROLOGY
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