Peritoneal Dialysis Access
A peritoneal dialysis (PD) access is a pathway to a patient’s peritoneal cavity that allows dialysis to occur.
Whether you choose an ambulatory or automated form of PD, you’ll need to have a soft catheter placed in your abdomen. The catheter is the tube that carries the dialysis solution into and out of your abdomen. If your doctor uses open surgery to insert your catheter, you will be placed under general anesthesia. Another technique requires only local anesthetic. Your doctor will make a small cut, often below and a little to the side of your navel (belly button), and then guide the catheter through the slit into the peritoneal cavity. As soon as the catheter is in place, you can start to receive solution through it, although you probably won’t begin a full schedule of exchanges for 2 to 3 weeks. This break-in period lets you build up scar tissue that will hold the catheter in place.
The standard catheter for PD is made of soft tubing for comfort. It has cuffs made of a polyester material, called Dacron, which merge with your scar tissue to keep it in place. The end of the tubing that is inside your abdomen has many holes to allow the free flow of solution in and out.
A hemodialysis access is a pathway to a patient’s bloodstream that allows dialysis to occur.
A vascular access must be created prior to starting regular hemodialysis treatments. This is the site on your body where blood will be removed and returned during dialysis. To maximize the amount of blood cleansed during hemodialysis, the vascular access should provide high volumes of blood flow continuously during treatments.
There are three basic kinds of vascular accesses for hemodialysis:
- an arteriovenous (AV) fistula
- an AV graft
- a catheter, when no other alternative
Southwest Kidney Institute and Southwest Kidney Dialysis strongly recommend AV fistulas as the access of choice. A fistula has fewer complications including less infections, clotting and need for repeated repairs, surgeries and hospitalization. Early placement of AV fistulas is required in order for them to mature and be available for use at the start of dialysis.
An AV fistula requires advance planning because a fistula takes a while after surgery to develop (in rare cases, as long as 24 months). A properly formed fistula is less likely than other kinds of vascular accesses to form clots or become infected.
A surgeon creates an AV fistula by connecting an artery directly to a vein, usually in the forearm. Connecting the artery to the vein causes more blood to flow into the vein. As a result, the vein grows larger and stronger, making repeated needle insertions for hemodialysis treatments easier.
If you have small veins that won’t develop properly into a fistula, you can get a vascular access that uses a synthetic tube implanted under the skin in your arm. The tube becomes an artificial vein that can be used repeatedly for needle placement and blood access during hemodialysis. A graft doesn’t need to develop as a fistula does, so it can be used sooner after placement, often within two or three weeks.
Compared with fistulas, grafts tend to have more problems with clotting or infection and need replacement sooner, but a well-cared-for graft can last for several years.
Venous Catheter for Temporary Access
If your kidney disease has progressed quickly, you may not have time to get a permanent vascular access before you start hemodialysis treatments. You may need to use a venous catheter as a temporary access.
A catheter is a tube inserted into a vein in the neck, chest, or leg near the groin. It has two chambers to allow two-way flow of blood. Once a catheter is placed, needle insertion is not necessary.
Catheters are not ideal for permanent access. They can clog, cause infection or narrowing of the veins in which they are placed. If you need to start hemodialysis immediately, a catheter will suffice for several weeks or months while your permanent access develops.
For some patients, fistula or graft surgery is not successful, and a long-term catheter access must be used. Catheters that will be needed for more than about three weeks are designed to be tunneled under the skin to increase comfort and reduce complications.
All three types of vascular access—AV fistula, AV graft, and venous catheter—can have complications that require further treatment or surgery. The most common complications are infection and low blood flow due to blood clotting in the access. Venous catheters are most likely to develop infection and clotting problems that may require medications and catheter removal or replacement.
AV grafts may also develop low blood flows indicating clotting or narrowing of the access. In this situation, the AV graft may require angioplasty which is a procedure to widen the small segment that is narrowed. Another option is to perform surgery on the AV graft and replace the narrow segment.
Infection and low blood flow are much less common in AV fistulas than in AV grafts and venous catheters. Still, having an AV fistula is not a guarantee against complications.
Access Needle Insertion
Each hemodialysis treatment requires needle insertion except for catheter accesses. Most dialysis centers use two needles—one to take blood out of the body and one to return the cleaned blood to your body. Some specialized needles are designed with two openings for two-way flow of blood, but these needles are less efficient. For some patients, use of this needle may mean longer treatments.
The two main types of needle insertion are the “ladder” and “buttonhole” strategies. The ladder strategy places the needles in a different location each session climbing up the length of the fistula so one area isn’t weaken by repeated needle sticks. The buttonhole strategy uses a limited number of sites inserting the needle precisely into the same hole made by the previous needle stick creating a tunnel similar to a pierced ear.
Taking Care of Your Access
You can do several things to protect your access:
- Make sure your nurse or technician checks your access before each treatment.
- Keep your access clean at all times.
- Use your access site only for dialysis.
- Be careful not to bump or cut your access.
- Don’t let anyone put a blood pressure cuff on your access arm.
- Don’t wear jewelry or tight clothes over your access site.
- Don’t sleep with your access arm under your head or body.
- Don’t lift heavy objects or put pressure on your access arm.
- Check the pulse in your access every day.