thumb|200px|Catheter for [[hemodialisis|hemodialysis]]
thumb|Central venous catheter for temporary access in hemodialysis
A dialysis catheter is a catheter used for exchanging blood to and from a hemodialysis machine and a patient.
The dialysis catheter contains two lumens: venous and arterial. Although both lumens are in the vein, the "arterial" lumen, like natural arteries, carries blood away from the heart, while the "venous" lumen returns blood towards the heart. The arterial lumen (typically red) withdraws blood from the patient and carries it to the dialysis machine, while the venous lumen (typically blue) returns blood to the patient (from the dialysis machine). Flow rates of dialysis catheters range between 200 and 500 ml/min.
If a patient requires long-term dialysis therapy, a chronic dialysis catheter will be inserted. Chronic catheters contain a dacron cuff that is tunneled beneath the skin approximately 3–8 cm. The tunnel is thought to add a barrier to infection. The most popular dialysis catheter sold on the market today is the Symmetrical-Tip dialysis catheter. This catheter is in the form spiral Z shape.
thumb|Permacath for dialysis
Types
Temporary access
Central venous catheters intended for temporary access (sin. Quinton catheters) are typically used for less than 21 days. These types of catheters are usually smaller in size, placed directly in the vein, and are two or three lumens in design. The third lumen is useful for administration of fluids, antibiotics, medicines, or contrast without having to find other places for intravenous access. This type of catheter is useful for initiating venous access for acute renal failure patients quickly for dialysis before a permanent catheter is inserted for long term access.
Permanent access
The lumens of this type of catheter is larger, have a cuff that tunnel under the skin away from the venous insertion site with only two lumens. The catheter course under the skin helps to prevent infection going into bloodstream, as seen in temporary catheters. as the risk of infections (e.g., endocarditis, bacteremia), hospitalization and death are lower.