Overview of Kidney Replacement Therapy

Kidney replacement therapy (KRT) replaces nonendocrine kidney function in patients with kidney failure and is occasionally used for some forms of poisoning. Techniques include continuous hemofiltration and hemodialysis, intermittent hemodialysis, and peritoneal dialysis. All of these modalities exchange solute and remove fluid from the blood, using dialysis and filtration across permeable membranes. Kidney replacement therapy also includes kidney transplantation.

KRT does not correct the endocrine abnormalities (decreased erythropoietin and 1,25-dihydroxyvitamin D3 production ) of kidney 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). Passive diffusion removes small-molecule metabolic waste (eg, urea, creatinine), replaces depleted substances (eg, bicarbonate), and balances electrolyte concentrations. During filtration, serum water passes between compartments down a hydrostatic pressure gradient, dragging solute with it (convective transport). Convective transport removes excess fluid and some larger-molecule solutes. Dialysis and filtration 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 almost exclusively for acute kidney injury. Continuous therapy is sometimes better tolerated than intermittent therapy in patients whose condition is unstable because solute and water are removed more slowly. All forms of KRT 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 Kidney Replacement Therapies lists indications and contraindications for the common forms of KRT.

Care of patients requiring long-term KRT 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 (1). Patient assessment should begin when end-stage kidney disease is anticipated but before KRT 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 KRT makes patients socially and emotionally vulnerable (1). It interrupts routine work, school, and leisure activities; creates anger, frustration, tension, and guilt surrounding dependency; and can alter 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 being nonadherent to recommended therapy.

Traits that have been shown to improve quality of life and self-management behaviors in patients with end-stage kidney disease receiving hemodialysis include resilience, self-efficacy, illness cognition, and self-esteem (2, 3, 4). Emotional stability, family encouragement, consistent treatment team support, and patient and family participation in decision-making are also important. Self-management programs, cognitive-behavioral therapy, exercise, and relaxation techniques have shown success in decreasing psychosocial problems (5, 6).