A port for dialysis, or vascular access, creates a pathway to the bloodstream for individuals undergoing hemodialysis. This specialized connection allows blood to be efficiently removed from the body, purified by a dialysis machine, and then returned. Its purpose is to provide a reliable and repeated entry point for the large volume of blood flow needed during dialysis sessions.
Understanding Vascular Access for Dialysis
There are three primary types of vascular access used for hemodialysis. The choice depends on individual patient factors and the urgency of dialysis initiation. These options include arteriovenous (AV) fistulas, arteriovenous (AV) grafts, and central venous catheters (CVCs).
An arteriovenous (AV) fistula is created surgically by connecting an artery directly to a vein, usually in the arm. This connection increases blood flow and pressure in the vein, causing it to enlarge and strengthen, a process known as maturation. Fistulas are the preferred access due to their longevity and lower rates of infection and clotting. However, they require several weeks to months to mature before use.
An arteriovenous (AV) graft involves surgically connecting an artery to a vein using a synthetic tube. This tube is typically placed in the arm, but can also be in the leg or chest. Grafts are an alternative when a patient’s veins are not suitable for a fistula, offering quicker readiness for use. While durable, grafts carry a higher risk of infection and clotting than fistulas and may not last as long.
A central venous catheter (CVC) is a soft tube inserted into a large vein, commonly in the neck, chest, or groin. CVCs are used when immediate dialysis is necessary, as they can be used right after placement. They are generally considered temporary solutions due to a higher likelihood of infection and blood clots compared to fistulas and grafts. Tunneled CVCs, placed under the skin, offer a slightly longer-term option.
How Vascular Access Facilitates Dialysis
The vascular access connects the patient’s circulatory system to the hemodialysis machine. During a dialysis session, blood is drawn, cleaned by the machine’s filter, and then returned. The access ensures a continuous and sufficient blood flow for effective waste removal.
For an AV fistula or graft, two needles are inserted into the access site at the start of each treatment. One needle draws blood to the dialysis machine, while the other returns the cleaned blood. This two-needle system allows for efficient circulation through the dialyzer, which functions as an artificial kidney. The high blood flow rate enables the machine to process a large volume of blood, ensuring thorough filtration.
For a central venous catheter, the connection to the dialysis machine is direct, without additional needles. CVCs have two separate lumens, or channels. One lumen transports blood to the dialysis machine, and the other returns the filtered blood. This design provides immediate access, useful in emergency situations or while a fistula or graft matures.
Caring for Your Dialysis Access
Proper daily care of your dialysis access is important for its long-term function and to prevent complications. Hygiene practices reduce infection risk. Patients should wash hands before touching the site and clean the area daily with mild soap and water. For CVCs, keep the dressing clean and dry, changing it as instructed by the care team.
Protecting the access from injury or pressure is also important. Patients should avoid sleeping on the arm with the access, wearing tight clothing, jewelry, or watches over the site. Also avoid carrying heavy items or allowing blood pressure measurements or blood draws on that arm. Regularly check the access by feeling for a gentle vibration (“thrill”) and listening for a soft whooshing sound (“bruit”) to monitor its function. Report any changes to the dialysis care team.
Potential Complications of Dialysis Access
Dialysis access sites can develop complications that may disrupt treatment. Recognizing the signs of these issues is important for timely medical intervention. Common problems include infection, clotting, narrowing of the vessel, and aneurysm formation.
Infection can occur at the access site, presenting with redness, swelling, warmth, pain, or drainage. Fever or chills might indicate a widespread infection. Catheters are more prone to infection than fistulas or grafts due to their external components. Prompt medical attention is necessary if an infection is suspected.
Clotting (thrombosis) can block blood flow within the access, making dialysis difficult or impossible. A change or absence of the thrill or bruit can signal a clot. Narrowing of the blood vessel (stenosis) can also reduce blood flow, leading to prolonged bleeding after dialysis or difficulty inserting needles. Aneurysms, a bulging of the vessel wall, can develop in fistulas or grafts due to repeated needle insertions or vessel weakening. These complications require evaluation by a healthcare professional to maintain the access’s function.