How does haemodialysis work?

The vascular approaches

Arteriovenous fistula (AVF)

The superficial veins do not have sufficient flow to allow hemodialysis. For this reason, the surgeon must create, under local anesthesia, an arteriovenous fistula (AVF). It is about connecting a vein to a nearby artery, so that part of the arterial blood is diverted into the vein. This one will dilate, under the effect of blood pressure, and ensure sufficient blood flow to be pricked easily.

A vein of the forearm or arm is most often chosen preferentially on the 'non-dominant' arm (that is to say, the left arm for the right-handed ones and vice versa), which is less solicited in everyday life. The time frame for its development varies: from a few weeks to several months. The fistula must be performed early enough to be well developed at the time of the need for dialysis.

Its puncture can be difficult at the beginning, but must improve within a few weeks. Puncture-related pain is reduced or eliminated by applying a local anaesthetic to the skin (cream or patch) at home at the puncture sites one hour before the dialysis session.

Complications can occur over time (excessive development, dysfunction, clotting...) requiring one or more surgical interventions or additional explorations (X-rays, ultrasound...).

Precautions must be taken to ensure its longevity. It is necessary to avoid:

To perform a blood test in the fistula or to take the blood pressure on the arm that carries the fistula,
To wear bracelets, heavy objects or clothes that make tourers.

The vascular prosthesis

There are several types. The most common is in goretex (PolyTetraFluoroEthylène). It is a flexible tube interposed between an artery and a vein at the level of the forearm, arm or thigh. Unlike the arteriovenous fistula, it is faster to use (2 to 3 weeks).

On the other hand, its malfunctions are more frequent and longevity reduced. It is only resorted to if the realization of an arteriovenous fistula is impossible. It is placed under general anesthesia in the operating room by a vascular surgeon after surgical and anesthetic consultation.

Blood vessel monitoring can be carried out beforehand by Doppler echo. The choice of site will be preferentially at the level of the 'non-dominant' arm.

How to puncture the arterio-venous fistula?

Two punctures are necessary on the fistula, with large-bore needles to facilitate blood flow:

A so-called arterial needle is used to aspirate the blood to be purified,
A so-called venous needle is used to reinject the purified blood.

These two needles are connected to the extracorporeal dialysis circuit, itself connected to the dialysis generator. To learn more about hemodialysis: