What Is the Dialysis With A Shunt?

During the dialysis, blood is artificially being washed and freed from harmful substances and water. This is also called blood purification and is made for people with kidneys that aren’t able to properly clean the blood anymore.
[Translate to englisch:] Dialyse Shunt

Patientin bei der Dialyse

The kidney purifies the organism and filters waste to avoid poisoning. It also regulates the mineral balance and the influence of blood pressure. The dialysis can temporarily take over this part, for example when it comes to chronic kidney failure. In the long term, however, dialysis cannot replace natural blood-washing. It is usually used to bypass the time until a donor kidney can be transplanted.

There is an external and internal form of the dialysis. With an internal form, the peritoneal dialysis takes place inside the body. On the outside (extracorporeal), the blood can be purified by an external dialysis device. The so-called dialyzer purifies the blood in an extracorporeal manner and then directs it back. To do this, one has to lay a shunt, to cater for a constant access to the blood vessels. If we talk about the extracorporeal way, one has to differ between hemodialysis and hemodiafiltration. The hemodialysis resorts to a fine pore filter, which is permeable for water and contaminants. The blood is pumped into the dialyzer via the shunt and freed of contaminants according to the principle of the concentration gradient (diffusion). After that, the purified blood is led back to the bloodstream via the shunt. Normally a hemodialysis with a shunt takes place up to three times a week for four to eight hours. The hemodiafiltration uses a large-pored dividing layer, which also allows blood to pass through. This loss is balanced by the addition of mineral solutions. Both in this method and in hemodialysis, it has been found that continuous administration can lead to an improved performance of the patient.

Why is the Shunt Used for a Dialysis?

When it comes to a puncture, doctors often resort to a vein, since it is just beneath the skin and easy to reach. Inside these veins, the blood flow is usually not strong enough. Arteries are deeper inside the body, but have a stronger blood flow. This is the requirement for the rapid exchange of the blood during dialysis. A puncture of the artery is not only more difficult, but also more painful. That’s why a shunt is used to artificially connect a vein with an artery, so that a higher blood flow is created. The shunt is usually applied to the forearm during a small operative procedure in the vessel surgery and conducted while the patient receives a local anesthesia. This approach is also called a Cimino Shunt. If a direct connection from a vein to an artery is not possible, the doctor will resort to synthetic connections, to set the shunt. Sometimes the elbow or the upper arm is used, if the shunt cannot be placed in the forearm. The vessels are especially small when it comes to children, So that an evasion is necessary when the shunt is set. In order to ensure easy handling for the patient, the shunt will be placed in the left arm if you are a right-handed person and into the right arm if you are left-handed. A few weeks after the operation, once the wound has healed without any complications, the shunt can be used for the dialysis.

Thanks to the shunt a permanent vessel access is possible with a puncture. The stronger blood flow from the artery to the vein results to an extension of the vein and gives it a more resilient wall. It is also easier to puncture, thanks to the shunt. But there are of course a few risks that come with the shunt. The main risk is the danger of an infection, since the shunt enables a direct connection from the bloodstream to the outside world. This can lead to bacterial infections, which can be avoided if one sticks to the hygienic guidelines. Another risk is the development of thromboses at the shunt, which can be removed by surgery. In principle, the shunt does not pose any risks, but an easier dialysis for all parties concerned.