During hemodialysis, blood is removed from the patient’s body, passed through a machine that mechanically removes toxins and impurities from the blood, after which it is returned to the patient. This process is often used for patients with long or short-term kidney failure. A catheter is often surgically implanted internally to simplify the process of accessing the blood supply. A tunneled hemodialysis catheter is one that is connected to the blood vessels in one area, but tunneled underneath and brought through the skin in another.
Surgery is often performed on patients who are expected to receive long-term hemodialyis, to make the process easier. A fistula, or opening between two body parts, is created between a vein and an artery, typically in the wrist or hand. Each time the person receives a treatment, usually three times per week, needles are inserted in the area of the fistula. One is designed to send the blood out to the machine and another is used to return the cleaned blood to the body.
This is an ongoing process, and most of the blood remains circulating in the patient’s body. Some blood is always in the hemodialysis machine, being cleaned. A fistula is used because it provides the easiest access to a rapid blood flow, making the hemodialysis process quicker.
Patients who are only temporarily on hemodialysis are not usually given a fistula. Instead, a catheter is surgically inserted into a large artery and stitched in place by the surgeon. Access is gained through ports on the ends of tubes connected to the catheter, so it is not necessary to poke the patient with multiple needles every time he or she has hemodialyis.
Sometimes the catheter is placed near the artery and exits the skin at the same spot. More often, the catheter is inserted into a large blood vessel such as the carotid artery in the neck, and it exits further down the body and through the chest wall. When a catheter is placed in the blood vessels in one spot and brought out of the body in another, it is referred to as a tunneled hemodialysis catheter.
There are two main reasons for using a tunneled hemodialysis catheter. The tunneling adds stability to the catheter, since it is harder to knock it loose when much of it is tunneled under the skin. Another reason for using a tunneled hemodialysis catheter is to help minimize the risk of infection. When a catheter is used, it creates a pathway for bacteria directly into the blood stream. The tunneling process separates the opening on the skin from where the catheter enters the body, reducing the risk of infection.