Overview of Renal Replacement Therapy

Renal replacement therapy (RRT) replaces nonendocrine kidney function in patients with renal failure Chronic Kidney Disease Chronic kidney disease (CKD) is long-standing, progressive deterioration of renal function. Symptoms develop slowly and in advanced stages include anorexia, nausea, vomiting, stomatitis, dysgeusia... read more and is occasionally used for some forms of poisoning. Techniques include continuous hemofiltration and hemodialysis Continuous Hemofiltration and Hemodialysis Continuous hemofiltration and hemodialysis procedures filter and dialyze blood without interruption. (See Overview of Renal Replacement Therapy for other renal replacement therapies.) The principal... read more , intermittent hemodialysis Hemodialysis In hemodialysis, a patient’s blood is pumped into a dialyzer containing 2 fluid compartments configured as bundles of hollow fiber capillary tubes or as parallel, sandwiched sheets of semipermeable... read more , and peritoneal dialysis Peritoneal Dialysis Peritoneal dialysis uses the peritoneum as a natural permeable membrane through which water and solutes can equilibrate. Compared to hemodialysis, peritoneal dialysis is Less physiologically... read more . All modalities exchange solute and remove fluid from the blood, using dialysis and filtration across permeable membranes.

RRT does not correct the endocrine abnormalities (decreased erythropoietin and 1,25-dihydroxyvitamin D3 production Vitamin D Deficiency and Dependency Inadequate exposure to sunlight predisposes to vitamin D deficiency. Deficiency impairs bone mineralization, causing rickets in children and osteomalacia in adults and possibly contributing... read more ) of renal failure. During dialysis, serum solute (eg, sodium, chloride, potassium, bicarbonate, calcium, magnesium, phosphate, urea, creatinine, uric acid) diffuses passively between fluid compartments down a concentration gradient (diffusive transport). During filtration, serum water passes between compartments down a hydrostatic pressure gradient, dragging solute with it (convective transport). The two processes are often used in combination (hemodiafiltration). Hemoperfusion is a rarely used technique that removes toxins by flowing blood over a bed of adsorbent material (usually a resin compound or charcoal).

Dialysis and filtration can be done intermittently or continuously. Continuous therapy is used almost exclusively for acute kidney injury Acute Kidney Injury (AKI) Acute kidney injury is a rapid decrease in renal function over days to weeks, causing an accumulation of nitrogenous products in the blood (azotemia) with or without reduction in amount of urine... read more . Continuous therapy is sometimes better tolerated than intermittent therapy in unstable patients because solute and water are removed more slowly. All forms of RRT except peritoneal dialysis require vascular access; continuous techniques require a direct arteriovenous or venovenous circuit.

The choice of technique depends on multiple factors, including the primary need (eg, solute or water removal or both), underlying indication (eg, acute or chronic kidney failure, poisoning), vascular access, hemodynamic stability, availability, local expertise, and patient preference and capability (eg, for home dialysis). The table Indications and Contraindications to Common Renal Replacement Therapies Indications and Contraindications to Common Renal Replacement Therapies lists indications and contraindications for the common forms of RRT.

Care of patients requiring long-term RRT Medical Aspects of Long-Term Renal Replacement Therapy All patients undergoing long-term renal replacement therapy (RRT) develop accompanying metabolic and other disorders. These disorders require appropriate attention and adjunctive treatment.... read more ideally involves a nephrologist, a psychiatrist, a social worker, a renal dietitian, dialysis nurses, a vascular surgeon (or other surgeon skilled in peritoneal dialysis catheter placement), and the transplant surgical team. Patient assessment should begin when end-stage renal failure Chronic Kidney Disease Chronic kidney disease (CKD) is long-standing, progressive deterioration of renal function. Symptoms develop slowly and in advanced stages include anorexia, nausea, vomiting, stomatitis, dysgeusia... read more is anticipated but before RRT is needed, so that care can be coordinated and patients can be educated about their options, evaluated for resources and needs, and have vascular access created.

Psychosocial evaluation is important because RRT makes patients socially and emotionally vulnerable. It interrupts routine work, school, and leisure activities; creates anger, frustration, tension, and guilt surrounding dependency; and alters body image because of reduced physical energy, loss of or change in sexual function, changed appearance due to access surgery, dialysis catheter placement, needle marks, bone disease, or other physical deterioration. Some patients react to these feelings by nonadherence or by being uncooperative with the treatment team.

Personality traits that improve prognosis for successful long-term adjustment include adaptability, independence, self-control, tolerance for frustration, and optimism. Emotional stability, family encouragement, consistent treatment team support, and patient and family participation in decision-making are also important. Programs that encourage patient independence and maximal resumption of former life interests are more successful in decreasing psychosocial problems.