Thursday, September 30, 2010

Peritoneal Dialysis

Photo: our Ricky enjoys the overnight cycler. I was going to use this picture for the article in the newspaper, had it all cropped, formatted, and ready to go, then changed my mind because I spotted something in the picture that I didn't think we needed to put in the paper. See if you can spot what it is. Much more private posting the picture on the web, right?

Part three of a series on the treatment of renal failure. Why? Because a year ago my husband's kidneys blinked out like a couple of light bulbs, and renal failure has been the center of our lives since. Writers are always told to “write what you know,” so – renal failure. Part 3:
Peritoneal dialysis (PD) is a way of cleansing the renal patient's blood by putting dialysate, a fancy word for dextrose solution (sugar water), into the peritoneum of the renal patient, letting the solution sit there for a few hours (this is called the “dwell”) pulling toxins and extra fluid across the peritoneal membrane, and then draining the dialysate and putting in fresh dialysate and starting over. No bloodletting involved.
The peritoneum is the cavity in your torso where your vital organs and your intestines live. The cavity is lined by the peritoneal membrane, a sac that holds everything together and is rich in blood vessels.
The problem when PD was first used was that the abdomen had to be freshly punctured (this would be bloodletting) for each dialysis procedure, in effect putting the patient through surgery once or twice a week. Attempts to leave catheters in place were not successful because the site of the puncture or the peritoneum became infected.
PD was being used and improved during the same years as hemodialysis, starting before World War II, but was not used commonly until the 1980s. This was because Henry Tenckhoff designed a catheter that would not cause infection.
Dr. Henry Tenckhoff began working with Belding Scribner at the UW, that hotbed of dialysis research, in 1963. When Tenckhoff began working with PD patients, he had to go to their homes twice a week to perform the minor surgery of inserting a catheter into the patient's abdomen.
Dr. Tenckhoff observed that PD worked well and that PD patients did better in many ways than patients on hemodialysis. Eventually he developed what is now known as the Tenckhoff catheter, which could be placed into a patient's abdomen and left there, and with proper care would not become infected.
The Tenckhoff catheter is a piece of tubing which enters the patient's abdomen and has a coil inside the peritoneum. This inner bit has little holes in it, like drain field pipe on a much smaller scale. The holes facilitate the entry and exit of the dialysate. The outer bit of the catheter is a length of tubing with a connection on the end for attaching a tube to drain and fill the peritoneum.
Once patients have a Tenckhoff catheter placed in their abdomens and they have healed from the surgery, they are trained on how to do PD and then they do it at home, with frequent monitoring by a PD nurse. Testing is done frequently to monitor how the patient is doing and whether dialysis is working. Sterile dialysate is delivered to the patient's home about once a month.
There are two kinds of PD: manual, and machine assisted.
In the manual variety, the patient typically does four exchanges a day in which dialysate is drained from the peritoneum, and fresh dialysate is put in and left in – the “dwell” - for four hours or so, and then drained and replaced. An exchange takes 30 to 40 minutes.
In machine assisted PD, the patient hooks up to a cycler machine at night which does exchanges while the patient sleeps. Unfortunately the machines set off alarms if anything isn't quite right – not enough dialysate draining is the most frequent problem. So these patients might not get much sleep at night.
My husband started on manual PD, which turned out to be a full time job, but now he's on the overnight cycler machine. He feels and looks better than he has since he became ill over a year ago. We like PD, alarms and all.
Not everyone can do PD, but it's an excellent way to go if you can.
Next time: Kidney transplants

Monday, September 20, 2010

Hemodialysis Gets Serious

Photos, left to right: Dr. Belding Scribner, inventor of the shunt; Wayne Quinton, who built the first shunt; Dr. James Cimino, Dr.Kenneth Appell, and Dr. Michael Brescia, who pioneered the AV fistula which is used for hemodialysis today.

Dr. Willem Kolff built the first dialysis machines, but they were made practical for treating end stage renal failure by Dr. Belding Scribner at the UW.
Scribner grew up in Chicago, got his medical degree at Stanford and did his post-grad work at the Mayo Clinic. He joined the faculty of the School of Medicine at the UW in 1951. Like Dr. Kolff, he was deeply affected by the deaths of renal patients.
Dr. Kolff's dialysis machines could get acute renal failure patients through a crisis until their kidneys began to function again, but patients with end-stage renal disease could not be saved. Surgery to open up access to veins and arteries damaged blood vessels so that after a few treatments it became impossible for doctors to access a patient's blood.
Scribner said that one night in 1959 he woke up with the idea for a shunt in the patient's arm, using plastic tubes, one inserted into an artery and one into a vein, with the tubes connected by a piece of tubing in between dialysis sessions. He brought his idea for the shunt to Wayne Quinton.
Wayne Quinton was a medical engineer at the UW in charge of building, maintaining, and inventing medical instruments for the Medical School. Quinton figured out how to build the shunt Scribner had envisioned. Suddenly it was possible for people to have long-term dialysis, and end stage renal disease went from fatal to treatable.
Right: the Quinton-Scribner shunt

There were only six dialysis machines in Seattle, though, and there were more renal patients than could be treated. Scribner decided that he would not make the decision of who would get dialysis. A committee was formed to review cases and decide who would receive treatment. The formation of this committee is recognized as the beginning of bioethics. Such committees decide who will and will not receive organ transplants, for example.
Dr. Scribner worked with the King County Medical Society to found the Seattle Artificial Kidney Center, which became the Northwest Kidney Centers, in January, 1962. It was the first out-patient dialysis center, and was the model for how hemodialysis is done today. Currently any patient who needs dialysis gets dialysis.
Scribner and Quentin had revolutionized hemodialysis, but the shunt had problems – clots tended to form in the tubing, for example.
Comes now Dr. Kenneth Appell, who grew up in Queens, New York. After serving in the Navy in the South Pacific during World War II, he returned to New York to complete his medical and surgical training.
Dr. Appell installed many of the Scribner shunts, but was not happy with the problems they had, chiefly clotting in the tubing. He came to believe that it would be possible to create an arteriovenus (AV) fistula in a renal patient's arm. This means that an artery would be stitched together with a vein, with a hole (fistula) in between that would allow arterial blood to flow directly into the vein, thereby avoiding the problems of the shunts. Arterial pressure on the vein causes it to enlarge. It takes weeks to months for a fistula to “mature,” but then two needles can be inserted into the vein regularly to remove blood for dialysis and put the filtered blood back into the patient's body. This is the “gold standard” for hemodialysis today.
Two of Appel's interns, Drs. James Cimino and Michael Brescia, began doing Dr. Appell's AV fistula surgery in 1966.
Right: a drawing showing how an AV fistula is constructed within the arm

Since the 1960s, millions of lives have been saved by hemodialysis and the techniques developed by Drs. Scribner, Appell, Cimino, and Brescia and their teams.
As for Wayne Quinton – in 1959 he quit his job at the UW and started a business called Quinton Instruments to market his inventions which the UW declined to develop. Most famous of these were the Scribner shunt, and a treadmill he invented for cardiac stress tests. Every treadmill you see today can trace its history to the self-winding mind of Wayne Quinton.
Right: A drawing Rick made of his "wristula" in December, 2009, when he was healing from the surgery