Vascular access provides a specialized connection to a patient’s bloodstream for hemodialysis treatments. Hemodialysis is a process that cleans the blood and removes excess fluid when kidneys are no longer able to perform these functions. The access point allows blood to flow from the body to a dialysis machine, where it is filtered, and then returned to the body.
Why Special Access is Needed for Dialysis
Standard veins in the body, such as those typically used for blood draws, are not robust enough for the demands of hemodialysis. These veins are delicate and would collapse under the high flow rates and repeated needle insertions required for treatment. Hemodialysis machines require large volumes of blood to be processed quickly, typically around a pint per minute, to effectively filter waste products from the body. Regular hemodialysis sessions are not possible without a specially prepared access point due to the fragility of peripheral veins.
Types of Dialysis Access
There are three primary types of vascular access used for hemodialysis: arteriovenous (AV) fistulas, AV grafts, and central venous catheters. Each type serves the same purpose of providing access to the bloodstream but differs in its creation and suitability for long-term use.
Arteriovenous (AV) Fistula
An arteriovenous (AV) fistula is a surgically created connection between an artery and a vein, usually in the arm. This direct connection causes increased blood flow and pressure into the vein, making it enlarge and strengthen over time, a process known as maturation. AV fistulas have a lower risk of infection and clotting, and they tend to last longer than other access types.
Arteriovenous (AV) Graft
When a patient’s veins are not suitable for an AV fistula, an arteriovenous (AV) graft may be used as an alternative. An AV graft involves using a synthetic tube to connect an artery to a vein, creating a pathway for blood flow. Grafts can be used sooner for dialysis than fistulas, typically within two to four weeks after placement. However, because they involve synthetic material, AV grafts carry a higher risk of infection and clotting compared to fistulas and may not last as long.
Central Venous Catheter (CVC)
A central venous catheter (CVC) is a flexible tube inserted into a large vein, most commonly in the neck, chest, or groin. CVCs are often used for urgent dialysis needs or as a temporary solution while a more permanent access, such as a fistula or graft, matures. They can be used immediately after insertion, but they pose a higher risk of infection and blood clots compared to fistulas and grafts, making them less ideal for long-term dialysis.
Creating Dialysis Access
Creating an AV fistula or graft typically involves a surgical procedure by a vascular surgeon, often outpatient. For an AV fistula, the surgeon makes a small incision, usually in the arm, to connect an artery directly to a vein. This procedure is often done under local or general anesthesia. After the surgery, an AV fistula requires several weeks to months, typically six to eight weeks, to mature and become strong enough for repeated needle insertions during dialysis.
For an AV graft
AV graft surgery also involves small incisions to connect an artery and a vein with a synthetic tube. The graft is tunneled under the skin to create a loop that allows for easier access. Similar to fistula surgery, graft placement is often an outpatient procedure under local anesthesia. Grafts generally become ready for use much sooner than fistulas, often within two to four weeks.
Central venous catheters
Central venous catheters are inserted into a large vein (neck, chest, or groin), often with ultrasound or X-ray guidance. This procedure is quicker than creating a fistula or graft and allows for immediate dialysis use. CVCs are held in place by stitches, some removed after a few weeks once secure.
Caring for Your Dialysis Access
Proper care of a dialysis access is important for its long-term function and to prevent complications. Regularly checking the access site is a key part of daily care. For AV fistulas and grafts, patients should feel for a “thrill,” which is a buzzing sensation, and listen for a “bruit,” a whooshing sound, indicating good blood flow. Any changes in these sensations, such as a weakening or disappearance of the thrill or bruit, should be reported to the healthcare team immediately.
Maintaining hygiene
Maintaining hygiene around the access site is important to reduce infection risk. The area should be washed gently with soap and water daily, particularly before dialysis. Patients should avoid tight clothing or jewelry on the access arm, and blood pressure measurements or draws should not be performed there. Activities that put direct pressure on the access, such as sleeping on the arm or carrying heavy bags, should be avoided.
Patients should monitor
Patients should monitor for signs of issues, including redness, swelling, warmth, pain, or drainage at the access site. Prolonged bleeding after dialysis, arm or hand swelling, or difficulty during needle insertion can indicate a problem. Promptly reporting concerns to healthcare providers ensures timely intervention and helps maintain dialysis access effectiveness.