Dialysis is an intensive treatment that involves cycling all of a person’s blood volume through a machine over 1-3 hours. Most veins, even big ones, won’t hold up under this kind of stress and duration. What kind of venous access is best for dialysis?
The best form of access is an AV fistula. This is a surgically created connection between an artery and a vein, usually in the upper arm or forearm, that can handle being repeatedly poked by needles and pumping out the kind of blood volume that dialysis requires. In order to find the best vessels, a mapping study with Doppler ultrasound is done ahead of time. A fistula has better flow, and lower rates of infection and blood clotting than other forms of access. The problem is that it takes 2-3 months to mature after surgery–so unless a patient has had conversations with an outpatient nephrologist, planned on having dialysis, and prepared for it ahead of time, this won’t be an option immediately available to many people.
The second-best option is an AV graft, which uses a small plastic tube to create the same connection between an artery and a vein that a fistula has. This can be ready to use in 2-3 weeks. However, there is a higher rate of complications from a graft, usually low blood flow from arterial narrowing. Angioplasty may be required to widen the artery again.
The most commonly used “bridging” form of access is the tunneled catheter (Hickman is one type), which is a central line that goes under the skin. This is often used in patients when you know several days ahead of time that they’ll need dialysis for at least several weeks, but aren’t able to use a fistula or graft. The tunneled cath is surgically inserted in a procedure that also requires general anesthesia and takes about 1 hour to place. It’s pretty much ready to use right away.
And finally, when you need to do dialysis like, right now, you can use a central line. It’s not that great, but in emergent cases, will do the job. While the tunneled cath is not intended to be used for more than several months, the central line should not be used for more than several weeks. These catheters are the most prone to infection and clotting.
See this helpful overview from the NIDDK for more details.