Renal Replacement Therapy
Renal replacement therapy (RRT) replaces nonendocrine kidney function in patients with renal failure and is occasionally used for some forms of poisoning.
There are three main modalities that is used to replace the renal function: dialysis (either hemodialysis or peritoneal dialysis), hemofiltration, and kidney transplant.
Dialysis focuses on the diffusion of molecules across a semipermeable membrane, which separates blood on one side and the dialysate on the other.
Hemofiltration is based upon the principles of filtration and convection, (as opposed to diffusion) and mimics the function of the glomerular system. An ultrafiltrate is excreted, and the replacement of electrolytes with a specific solution is essential.
Kidney transplantation is indicated for patients with end-stage renal disease (ESRD). In such cases, it associates with a greater long-term survival rate and a better quality of life than dialysis.
Molecules diffuse across a semipermeable membrane down their concentration gradient and are removed from the blood.
Superior at removing low-weight molecules (e.g., urea, protein-bound drugs, ammonia).
Requires either a catheter (short-term option) or the creation and maturation of a fistula (long-term option)
Molecules are filtered out by a semipermeable membrane, whereas fluid passes through freely and re-enters the body (as “ultrafiltrate”).
Superior at removing middle-weight molecules (e.g., TNF, IL-8, IL-6) Replacement fluid is needed due to significant amounts of fluid are wasted in this process (“effluent”).