A dialysis catheter is a flexible tube inserted into a large vein for hemodialysis treatment. This device is classified as a central venous catheter because its tip rests within a major blood vessel close to the heart, typically in the superior vena cava or right atrium. Its function is to facilitate the high blood flow rates required for efficiently filtering waste products and excess fluid from the blood. The catheter acts as a temporary or transitional bridge when more durable access options are not yet available or have failed.
The Purpose and Function of Dialysis Catheters
A catheter is required for urgent dialysis due to sudden kidney failure or severe electrolyte imbalances, enabling immediate vascular access. It is also commonly used as a transitional measure for patients with chronic kidney disease who are awaiting the maturation of a permanent access site, such as an arteriovenous (AV) fistula or AV graft. While an AV fistula is the preferred long-term access due to lower infection and complication rates, it takes several weeks or months to become ready for use. The catheter provides a reliable connection to the dialysis machine during this waiting period, preventing delays in therapy.
The device is designed with two distinct channels, known as lumens, to manage the blood flow simultaneously. The “arterial” lumen draws blood away from the patient’s circulation to be sent to the dialysis machine for cleaning. Concurrently, the “venous” lumen returns the newly filtered blood back into the bloodstream.
Primary Access Sites for Catheter Placement
The location of the catheter is determined by the specific large central vein targeted for insertion, with the goal of achieving optimal blood flow and minimizing complications. The right internal jugular vein, located in the neck, is the most frequently chosen site for long-term placement. This vein offers the most direct path down to the superior vena cava and the heart, ensuring high blood flow and reducing the risk of clotting or malfunction. Using the right side is associated with fewer complications compared to the left jugular vein.
Another possible location is the femoral vein, situated in the groin area. Access through the femoral vein is typically reserved for emergency situations when immediate upper-body access is unavailable or contraindicated. This site is generally avoided for extended use because it carries a higher risk of infection due to its proximity to the perineal area and can be less comfortable for a mobile patient. However, it is considered an acceptable temporary option until a long-term access can be created, as it preserves upper-body vessels for future use.
The subclavian vein, found under the collarbone, is avoided for dialysis catheter placement. The primary concern with this site is the increased risk of central vein stenosis, which is a narrowing of the vein. This stenosis can compromise the future use of the arm’s blood vessels for creating an AV fistula or graft, potentially removing all upper-body options for permanent vascular access.
Distinguishing Temporary and Permanent Catheters
Dialysis catheters are differentiated by their design and how they are secured beneath the skin, which dictates their intended duration of use. Non-tunneled catheters are designed for short-term access, typically lasting only a few days up to three weeks. These catheters are inserted directly into the chosen vein and exit the skin at the insertion site, with the placement often occurring in the internal jugular or femoral vein. Their simpler design allows for quick placement in urgent situations, but the direct path from the skin to the vein makes them highly susceptible to infection.
For patients requiring access for a longer period, such as several months or years, a tunneled catheter is utilized. This type involves a more involved placement procedure where the catheter is threaded several inches beneath the skin, creating a subcutaneous tunnel before it enters the central vein. This “tunnel” acts as a physical barrier, separating the skin exit site from the vein entry point, which substantially reduces the risk of bacteria traveling into the bloodstream.
Many tunneled catheters also incorporate a small polyester cuff, or Dacron cuff, embedded within this subcutaneous tunnel. Over time, scar tissue grows into this cuff, anchoring the catheter securely in place and reinforcing the infection barrier. Tunneled catheters usually exit the body on the chest wall, allowing the patient more comfort and mobility compared to a non-tunneled counterpart.
Daily Care and Precautions
Proper maintenance of the catheter exit site prevents bloodstream infection. The area where the catheter exits the skin must be kept clean and dry at all times, including during bathing. The dressing covering the site should be changed by trained medical staff using sterile techniques, typically at each dialysis session or at least weekly, to maintain a sterile environment. Patients must avoid water exposure, especially immersion in tubs or swimming pools.
Patients should avoid touching, scratching, or manipulating the catheter or its dressing, as this can introduce bacteria. Never use sharp objects, like scissors, near the catheter tubing, and ensure the line is not bent or kinked. It is important to monitor the site daily for signs of infection, which include increased pain, redness, swelling, warmth, or any pus-like drainage around the exit site. Any sudden fever or chills should be reported to a healthcare provider immediately, as these can signal a severe infection that requires urgent medical attention.