What is dialysis?
Dialysis, or renal replacement therapy (RRT), is the removal of toxins the body produces with a special machine that acts in place of the kidneys. When your kidney doctor (nephrologist) recommends dialysis, that means that your kidneys are no longer able to remove enough of the toxins to maintain your health. Vascular surgeons specialize in the surgery to allow dialysis.
What is hemodialysis?
Hemodialysis is the direct cleansing of blood with a special machine that clears the toxins which the kidneys would have normally excreted in the urine. Blood must be removed from the body, cleaned in a machine, and given back to the patient.
What are the options for hemodialysis? What are the risks and benefits of each?
A hemodialysis catheter which has two "ports" can allow blood to be taken out of the body through one port and infused back into the body with the other port. This catheter is tunneled under the skin, usually just below the collar bone, and inserted through a large vein – typically the jugular vein in the neck. While a hemodialysis catheter requires no pain for each dialysis session, they can malfunction and become infected, and they are far less reliable than a fistula (see below).
An arteriovenous fistula is a connection of an artery and a vein, typically in the upper extremity (arm or forearm). The connection of the artery and the vein requires surgery. When an artery is connected to a vein, some of the blood that would have gone to the hand is re-routed into the vein. The vein is very thin-walled and slowly expands over time (6-12 weeks). The vein can then become large enough so that two needles can be inserted into the vein – one to draw blood out and one to give blood back. An arteriovenous fistula is the most reliable form of dialysis, and the risk of infection is almost zero. We recommend fistulas in all patients undergoing hemodialysis who have suitable veins and are fit for surgery.
An arteriovenous graft (shunt) is an artificial blood vessel that acts like a fistula. It requires surgery also, but it needs only 2-3 weeks before hemodialysis can be performed. Grafts are far less reliable than fistulas, although it is difficult to predict how any individual graft will perform. Some work for years without problems, but some need maintenance after only a few months.
With both fistulas and grafts, the main risks of surgery are bleeding, infection, nerve injury, and decreasing the blood flow to the hand too much.
What is peritoneal dialysis (PD)?
Inside the abdomen, a large potential space exists between the internal organs and the muscles and tissue that form the abdominal wall. This space can be filled with a special dialysis fluid through a catheter going into the abdomen, and the fluid draws out the toxins that the kidneys normally excrete into the urine. Typically, the abdomen is filled with fluid just before bedtime, and the fluid draws out the toxins overnight. In the morning, the fluid is emptied.
What are the advantages of peritoneal dialysis?
Peritoneal dialysis can be performed at home. Patients do not need to go to a dialysis center.
What are the disadvantages of peritoneal dialysis?
Not all patients are candidates for PD. Patients who have had major surgery in their abdomen may have too much scar tissue to allow the dialysis fluid to be effective. Also, PD requires a significant commitment by the patient to maintain the catheter, which must be kept sterile during the fluid exchanges.
Infection of the PD catheter is the most significant risk. Serious infection requires removal of the PD catheter – a surgical procedure that requires general anesthesia in the operating room. In this case, the patient must start hemodialysis immediately. Sometimes PD can be resumed several weeks after the infection clears, but this requires placement of a new catheter.
Catheter dysfunction is another risk. The internal organs as well as the fat normally found inside the belly can interfere with the flow of fluid through the catheter. If the catheter stops working, another surgery (usually minimally invasive) is required to free the catheter from the intestines or fat which caused the obstruction.