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Dialysis and transplantation are life-prolonging therapies for many patients with renal insufficiency. The term end-stage renal disease (ESRD) describes the late stages of chronic renal failure. Initially, patients with ESRD are managed with conservative therapy, but eventually they require hemodialysis, peritoneal dialysis, and/or transplantation.
The correlation of uremic symptoms with renal function varies from patient to patient depending on the cause of renal disease (earlier onset of symptoms in subjects with diabetes mellitus), muscle mass (large, muscular patients tolerate high levels of azotemia), diet, nutritional status, and coexisting conditions.
DIALYSIS AND/OR TRANSPLANTATION
Selection of patients to receive dialysis and/or transplantation is a matter of some debate. Because of the reversible nature of acute renal failure, all patients with this diagnosis should be supported with dialysis, at least for some period of time, to allow return of renal function.
The recipient should be free of life-threatening extrarenal complications such as cancer, severe coronary artery disease, and cerebrovascular disease. Provided that diffuse vascular involvement is not present, diabetes mellitus is not a contraindication. Oxalosis may recur in relatively short order in a transplanted kidney and is generally a contraindication for transplantation.
Criteria for treatment with hemodialysis or peritoneal dialysis are more liberal because dialysis has less morbidity than transplantation in older patients with the aforementioned medical complications. Because of the cost of these programs, some have suggested that entry be restricted.
PREPARATION FOR THERAPY OF END-STAGE RENAL DISEASE
While conservative measures are being carried out in patients with chronic renal failure, it is important to prepare them with an intensive educational program, explaining the likelihood and timing of complete renal failure and the various forms of therapy available. The more knowledgeable patients are concerning hemodialysis, peritoneal dialysis, and transplantation, the easier and more appropriate.
DIALYSIS
HEMODIALYSIS
Hemodialysis employs the process of diffusion across a semipermeable membrane to remove unwanted substances from the blood while adding desirable components. A constant flow of blood on one side of the membrane and a cleansing solution (dialysate).
Hemodialysis equipment consists of three components:the blood delivery system, the composition and delivery system of the dialysate, and the dialyzer itself. Blood is pumped to the dialyzer by a roller pump through lines with appropriate equipment to measure flow and pressures within the system; blood flow should be approximately 300 to 450 mL/min.
The principal dialyzer in use in the United States is the hollow fiber or capillary dialyzer, in which membrane material is spun into fine capillaries, thousands of which are packed into bundles with blood flowing through the capillaries while dialysate is circulated on the outside of the fiber bundle.
PERITONEAL DIALYSIS
Peritoneal dialysis, like hemodialysis, may be performed in various settings and with several techniques. In patients with acute renal failure, intermittent peritoneal dialysis (IPD) has largely been replaced by CAVHD or CAVVHD. Chronic peritoneal dialysis was attempted in the late 1940s but was impractical until the development of a permanent peritoneal catheterthe Tenckhoff catheter.
TRANSPLANTATION
Transplantation of the human kidney is frequently the most effective treatment of advanced chronic renal failure. Worldwide, tens of thousands of such procedures have been performed. When azathioprine and prednisone were initially used as immunosuppressive drugs, the results with properly matched familial donors were superior to those with organs from cadaveric donors, namely, 75 to 90 percent compared with 50 to 60 percent graft survival rates at 1 year. During the 1970s and 1980s, the success rate at the 1-year mark for cadaveric transplants rose progressively.
DONOR SELECTION
Donors can be cadavers or volunteer living donors. The latter are usually family members selected to have at least partial compatibility for HLA antigens.
In the United States, there is a coordinated national system (United Network for Organ Sharing) of computerized information about and logistic support for the transportation of cadaver kidneys to suitable recipients.
TISSUE TYPING AND CLINICAL IMMUNOGENETICS
Matching for antigens of the HLA major histocompatibility gene complex is the ideal criterion for selection of donors for renal allografts.
Living Donors When first-degree relatives are donors, graft survival rates at 1 year are slightly greater than those for cadaver grafts, with the exception of HLA-identical donors.