The decision to initiate dialysis for the management of end-stage renal disease (ESRD) usually depends on a combination of the pt’s symptoms, comorbid conditions, and laboratory parameters. Unless a living donor is identified, transplantation is deferred by necessity, due to the scarcity of deceased donor organs (median waiting time, 3–6 years at most transplant centers). Dialytic options include hemodialysis and peritoneal dialysis (PD). Roughly 85% of U.S. pts are started on hemodialysis. All three forms of “renal replacement therapy” (RRT) require planning and preparation months to years before ESRD occurs; early referral to a nephrologist is thus critical for successful RRT.
Absolute indications for dialysis include severe volume overload refractory to diuretic agents, severe hyperkalemia and/or acidosis, severe encephalopathy not otherwise explained, and pericarditis or other serositis. Additional indications for dialysis include symptomatic uremia (Chap. 142) (e.g., intractable fatigue, anorexia, dysgeusia, nausea, vomiting, pruritus, difficulty maintaining attention and concentration) and protein-energy malnutrition/failure to thrive without other overt cause. No absolute serum creatinine, blood urea nitrogen, creatinine or urea clearance, or glomerular filtration rate (GFR) is used as an absolute cutoff for requiring dialysis, although most individuals experience, or will soon develop, symptoms and complications when the GFR is below ∼10 mL/min. However, the “pre-emptive” initiation of dialysis in such pts, prior to the onset of clinical indications, does not improve outcomes in ESRD.
This requires direct access to the circulation, either via a native arteriovenous fistula (AVF—the preferred method of vascular access), usually at the wrist (a “Brescia-Cimino” fistula); an arteriovenous graft, usually made of polytetrafluoroethylene; a large-bore intravenous catheter; or a subcutaneous device attached to intravascular catheters. For pts with known, progressive CKD, planning of future dialysis is critical, involving creation of an AVF many months before dialysis is necessary so as to allow for healing and vascular maturation. Blood is pumped through hollow fibers of an artificial kidney (the “dialyzer”) and bathed with a solution of favorable chemical composition (isotonic, free of urea and other nitrogenous compounds, and generally low in potassium). Dialysate [K+] is varied from 1 to 4 mM, depending on predialysis [K+] and the clinical setting. Dialysate [Ca2+] is typically 2.5 mg/dL (1.25 mM), [HCO3–] typically 35 meq/L, and dialysate [Na+] 140 mM; these can also be modified, depending on the clinical situation. Most pts undergo dialysis thrice weekly, usually for 3–4 h. The efficiency of dialysis is largely dependent on the duration of dialysis, blood flow rate, dialysate flow rate, and surface area of the dialyzer.
Complications of hemodialysis are outlined in Table 143-1. Many of these relate to the process of hemodialysis as an intense, intermittent therapy. In contrast to the native kidney or to PD, both major dialytic functions (i.e., clearance of solutes and fluid removal, or “ultrafiltration”) are accomplished over relatively short time periods. The ...