Buy the Book PDA Download

Update Me E-mail alerts The Merck Manual Minute

Print This Topic Email This Topic

Renal replacement therapy (RRT) replaces nonendocrine kidney function in patients with renal failure and is occasionally used for some forms of poisoning. Techniques include intermittent hemodialysis, continuous hemofiltration and hemodialysis, and peritoneal dialysis. 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) of renal failure. In dialysis, serum solute (eg, Na, Cl, K, HCO₃, Ca, Mg, phosphate, urea, creatinine, uric acid) diffuses passively between fluid compartments down a concentration gradient (diffusive transport). In 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 performed intermittently or continuously. Continuous therapy is used exclusively for acute renal failure; benefits over intermittent therapy are improved tolerability as a result of slower removal of solute and water. 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 failure, poisoning), vascular access, hemodynamic stability, availability, local expertise, and patient preference. Table 1: Renal Replacement Therapy: Indications and Contraindications to Common Renal Replacement Therapies lists indications and contraindications for the common forms of RRT.

Table 1
Indications and Contraindications to Common Renal Replacement Therapies Renal Replacement Therapy Indications Contraindications Hemodialysis Renal insufficiency or failure (acute or chronic) with any of the following that cannot otherwise be controlled: Fluid overload Hyperkalemia Hypercalcemia Metabolic acidosis Pericarditis Uremic symptoms GFR < 10 mL/min/1.73 m2 BSA (chronic renal failure, no diabetes) GFR < 15 mL/min/1.73 m2 BSA (chronic renal failure, diabetes) Some poisonings (see Poisoning) Uncooperative or hemodynamically unstable patient Peritoneal dialysis Same indications as for hemodialysis (except for poisonings) in patients who: Have inadequate vascular access or Prefer self-therapy Absolute: Loss of peritoneal function or adhesions that limit dialysate flow, recent abdominal wounds, abdominal fistulas, abdominal wall defects that prevent effective dialysis or increase infection risk (eg, irreparable inguinal or diaphragmatic hernia, bladder extrophy), patient's condition not amenable to dialysis Relative: Abdominal wall infection, frequent episodes of diverticulitis, inability to tolerate large volumes of peritoneal dialysate, inflammatory bowel disease, ischemic colitis, morbid obesity, peritoneal leaks, severe undernutrition Hemoperfusion Poisoning or toxicity (eg, due to barbiturates, many antidepressants, ethchlorvynol, meprobamate Some Trade Names EQUANIL MILTOWN Click for Drug Monograph , paraquat, glutethimide, metals such as lithium Some Trade Names ESKALITH LITHOBID LITHONATE Click for Drug Monograph and barium, toxic doses of aminoglycosides or cardiovascular drugs) Uncooperative or hemodynamically unstable patient BSA = body surface area. For calculation of GFR see Approach to the Genitourinary Patient: GFR

Care of patients requiring long-term RRT ideally involves a nephrologist, psychiatrist, social worker, renal dietitian, dialysis nurses, and the transplant surgical team. Patient assessment should begin when end-stage renal failure 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 or change in sexual function, changed appearance due to access surgery, dialysis catheter placement, needle marks, bone disease, or other physical deterioration. Some patients express 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.

Last full review/revision December 2007 by James I. McMillan, MD

Content last modified December 2007