Dialysis, kidney

The kidneys perform the vital function of filtering waste materials out of the blood. When the kidneys stop functioning, death due to waste buildup occursquickly. As early as 1861 a Scottish chemist, Thomas Graham (1748-1843), described a procedure he called dialysis to purify the blood in cases ofkidney failure. The blood would be diffused across a membrane that allowed wastes to pass into a balanced fluid, while replenishing substances would pass from the fluid into the blood. Practical application of dialysis wasdeveloped by John Jacob Abel, the first professor of pharmacology at Johns Hopkins University School of Medicine. In 1912 Abel was investigating byproducts in the blood, and needed a device to filter these substances out. With colleagues Benjamin Turner and Leonard Rowntree, he built a machine that circulated blood through celloidin tubing immersed in a saline-dextrose solution andwrapped around a rotating drum. Urea and other toxins passed out into the solution, and oxygen passed into the blood. Abel tested this process, which he called vividiffusion, on rabbits and dogs, and published the findings in 1914. A major problem, however, was the tendency of the blood to clot whilecirculating through the tubes. Abel had used hirudin , an anticoagulant obtained from leeches, to prevent clotting. Once the effective anticlotting agent heparin became widely available, dialysis was ready for clinical use.

Several pioneers developed early versions of dialysis machines during World War II when many injured soldiers and civilians suffered kidney damage and died. In 1937, a young Dutch physician, Willem Kolff, working in Groningen, Holland, had already put together a crude dialyzing machine and worked torefine it. After the Germans occupied the Netherlands in 1941, Kolff moved toKampen where, in spite of wartime shortages, he constructed a dialysis machine using cellophane tubing and beer cans. He first used his device on a humanpatient in March 1943 and, although all but one of the 15 patients he treated from 1943 to 1944 died, he persevered. By the end of the war, Kolff had refined his machine and began to promote its use, bringing dialyzers to The Hague, Amsterdam, and London. Meanwhile, with no knowledge of Kolff's work, NilsAlwall of Sweden and G. Murray of Canada were also developing a dialysis machine. In 1947 Kolff brought blueprints for his latest machine to doctors at Peter Bent Brigham Hospital at Harvard Medical School in Boston. These doctors,along with John Merrell, Karl Walter, and George Thorn, developed kidney dialysis into a standard treatment, using it to support patients in their pioneering kidney transplantations in 1954. Kidney transplants, the first organs ever to be transplanted, were made possible because of dialysis, which kept thepatient alive until the transplanted kidney began functioning or by maintaining patients awaiting a donor organ. Long-term dialysis was not possible, however, until 1960, because each time a patient was attached to a dialysis machine, both an artery and a vein had to be punctured, leading to eventual vessel deterioration. Dr. Belding Scribner of Seattle overcame this problem when he designed a Teflon and Silastic shunt (two parallel tubes with a U-connection) that could be inserted into a patient's artery and vein and left in placefor months or even years.

Today, hemodialysis, a refined version of this technique, allows the patient the option of home treatment with the aid of a family member or friend, or by specialists at a dialysis center. Patients also have the option of using Peritoneal dialysis, in which the abdomen lining (peritoneal membrane) filters waste from the blood into a cleansing solution called dialystate. Continuous Ambulatory Peritoneal Dialysis, the most common ofthree types, requires no machine and can be done by the patient. The dialystate, contained in a plastic bag, is transported through a permanent catheterinserted into the abdomen. The catheter is then plugged and, after four to six hours, the patient removes the plug, draining the solution containing wastematter back into the bag, which is then disposed of. This process is repeated continuously. Continuous Cyclic Peritoneal Dialysis is a similar function done by a machine connected to the catheter and performed at night while the patient sleeps. This procedure lasts from 10 to 12 hours every night. Intermittent Peritoneal Dialysis can also be done at home with a similar machine, but is usually done in hospital several times a week for a total of 36 to 42 hours. Some sessions may last 24 hours.

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