Dialysis shunt - arteriovenous shunt
In case of severe impairment or absence of kidney function, it is necessary to perform hemodialysis regularly through a dialysis machine (blood dialysis) in a hemodialysis center, so that metabolic products and harmful substances that are transferred by the kidneys into the patient's bloodstream can leave the blood.
Reasons for dialysis sessions
There are several causes of kidney damage that make it possible to connect an artificial dialysis machine (chronic renal failure, end stage renal failure). These include long-term diabetes mellitus (diabetes), chronic kidney disease, cystic kidneys as well as medications, immune system disease (glomerulonephritis), high blood pressure or, in rare cases, damage to kidney tissue due to other causes.
Symptoms for dialysis patients
With chronic renal failure, there is an increase in the amount of urine at first and then a decrease. Water retention (edema) forms in the body, for example in the legs and lungs. In the long term, hormone problems cause high blood pressure, a lack of red blood cells (anemia), and osteoporosis. As toxins can no longer be adequately eliminated, further organ damage may occur. Yellow skin discoloration is often noticeable. In the advanced stage (stage IV, terminal renal failure, uremic toxemia ) there is nausea, vomiting, bad breath, disorders of the brain, nerves and other organs.
Diagnosis of the need for hemodialysis
First, the patient is questioned and physically examined in the dialysis center. Your blood, urine, and kidneys will be examined with an ultrasound.
End-stage kidney disease that requires dialysis is usually clearly diagnosed through medical history and examinations.
Within a hospital dialysis unit, a dialysis machine is connected to the bloodstream where blood is transferred from the patient to the dialysis machines, where it reaches a semi-permeable membrane. This filters toxins, metabolic waste and excess fluid from the blood, which flows back into the patient's body in a purified state.
Hemodialysis sessions included other forms, such as peritoneal dialysis, using the membranous peritoneum (the layer lining the abdominal cavity, peritoneum) as a membrane.
There must be access to a blood vessel to connect the dialysis machine. When dialysis is needed, a catheter is inserted into a large vein, for example in the neck or collar vein.
Establishment of a dialysis shunt for the first time
Superficial veins that are punctured for dialysis, get clogged with blood clots (thrombosis) after a short time, and blood flow becomes insufficient. Therefore, a connection is established from this vein to the nearby artery, and this is then referred to as an arteriovenous shunt or an arteriovenous fistula.
The operation can be performed under local or regional anesthesia (numbing a larger area of the body). General anesthesia is also possible, but kidney patients do not need to have it frequently for such procedures.
A new dialysis shunt is usually done on the forearm; The procedure can also be performed on veins in the upper arm, elbow, or leg. If the forearm is taken, the end of the vein that runs from the thumb to the arm is sutured into an adjacent artery (Simino shunt). It is preferable to use the left arm for right-handed people and the right arm for left-handed people to reach a shunt for dialysis.
If there is an artery in the desired area, but no suitable vein, it can also be removed from the patient's own body, usually the leg, and implanted, or a plastic vascular prosthesis (graft) can be inserted. In order to ensure a greater vascular path for subsequent repeated perforations, the shunt can be placed in a zigzag path.
The condition of the new blood vessels can be checked and evaluated by X-ray examination with injection of contrast agent.
Surgical interventions on pre-existing dialysis shunt
A blood clot (thrombosis) that has formed inside the shunt can block it and must be removed with surgery. For this purpose, the shunt is opened, and a catheter with a balloon mechanism that can be filled and inflated is inserted behind the clot. The thrombus and catheter can then be pulled into the open area and easily removed there. Here, too, an X-ray contrast agent examination can be performed for evaluation. After the clot is successfully removed, the shunt is sutured, often by inserting a strip (graft) made of plastic or a vein taken from another part of the body, usually the leg.
If there is not enough blood for dialysis in the shunt, the shunt connection can be moved to another area, for example in the upper arm or in the bend of the elbow. If the shunt vessel is no longer in good condition or a bulge (aneurysm) has formed, it can be replaced with a vein from your body or a plastic replica of the blood vessel (graft).
If too much blood enters the shunt, the connection must be made tighter on the one hand to protect the heart, which has to do extra work, and on the other to ensure blood reaches the arm or leg.
Dialysis shunt removal
When kidney function is ensured again in those affected, for example after a kidney transplant, or when another functioning shunt is applied, the vascular junction can be attached with a suture. The vein often remains open due to other flows and can be diverted again later if necessary.
Possible additional procedures for operation
If during the operation there are unexpected and more extensive results, pathological changes or other complications, other or different measures may be necessary. This also includes widening narrowed blood vessels by balloon dilatation, dissolving blood clots with certain active ingredients (hydrolysis) or inserting an endovascular stent (STENT).
Complications of dialysis shunt surgery
Slight discomfort and pain usually go away in a short time. Injuries to adjacent structures can occur. If a blood vessel is damaged or the suture is opened, hemorrhage, secondary hemorrhage, and hematomas (ecchymosis) can occur. On the other hand, blood clots can build up in the shunt, and they can break off and block other blood vessels. A bulging shunt (aneurysm) may also occur. Nerve damage can lead to numbness and paralysis. There is a risk that infection, inflammation, wound healing disorders and scarring may develop. Infection in the shunt area can lead to life-threatening bacteremia (infection spreads through the bloodstream). Another complication is allergy.
Alarm after dialysis shunt
A newly created shunt (arteriovenous fistula) becomes thicker over time and the vessel wall becomes generally stronger. After several weeks, the first dialysis hole can be done through this shunt. The shunt often lasts for several years, sometimes 10 years or more. However, it may stop working at an early stage.
Despite medical advances, the life expectancy of patients on dialysis is lower than that of patients with healthy kidneys: the 10-year survival rate in dialysis patients is more than 50 %. Prognosis depends on comorbidities and age of the patient. A kidney transplant may be used.
So people with end-stage kidney disease (kidney failure) need to remove waste products from the bloodstream by connecting a dialysis machine to the patient's bloodstream (hospital dialysis department) or for a kidney transplant as a treatment for kidney disease to survive.
Before the dialysis shunt
If necessary, drugs that inhibit blood clotting, such as Marcumar® or Aspirin®, should be discontinued, in consultation with the physician. Medicines containing the active ingredient metformin used in diabetes mellitus (diabetes) may also be omitted before the contrast agent is tested.
After dialysis shunt
If the operation is performed on an outpatient basis, a companion must be present to accompany the patient, as the patient is not allowed to drive a car for 24 hours.
The arm or leg should initially be shifted high and not pressed. Later there are almost no restrictions, only injuries should be avoided, as they can lead to more profuse bleeding.
Adequate skin hygiene should be observed in the area of the dialysis shunt. The focused shunt must also be checked repeatedly by patients, for example, blood flow can be felt. In the event of any abnormalities, you should contact your doctor or go to a hospital.
The most important frequently asked questions about dialysis shunt in Turkey
What is the average age of a dialysis diversion?
Dialysis shunt remains usable on average for 2-3 years
What should I avoid in the hand where I have a dialysis shunt?
Do not take blood pressure measurements from the shunt arm. Avoid taking any blood tests from this arm or taking needles or injections into it. It is also preferable not to wear any tight or restrictive clothing on the arm of the fistula and avoid sleeping on it.