Renal replacement therapy

Renal replacement therapy (RRT(RRT) (also called renal dialysis or just dialysis) is used to supplement renal function in patients with either end-stage chronic kidney disease or medically-refractory acute renal impairment.

Theory

Haemodialysis refers to the diffusion of solutes in solution across a semiselectively-permeable membrane along an electrochemical concentration gradient. The goal of dialysis is to remove the excess solutes (e.g. urea, potassium, hydrogen ions) from the patient, whose renal excretion of these is impaired and to transport the solutes (e.g. bicarbonate) that the patient is deficient in from a solution known as the dialysate into the patient's blood. Excess fluid from the patient may also be removed by a process known as ultrafiltration ¹.

Peritoneal dialysis refers to using the natural peritoneal membrane as the semiselectively-permeable membrane. This is accessed through a peritoneal dialysis catheter (e.g. Tenckhoff catheter).

Haemodialysis uses a dialysis machine external to the patient to accomplish this solute diffusion. In the outpatient/home dialysis setting access is achieved ideally via the creation of an arteriovenous fistula ideally.

Types

• peritoneal dialysis
• haemodialysis

Complications

Complications arising from renal replacement therapy can pertain to the dialysis itself (e.g. electrolyte abnormalities), complications from the insertion of the catheter or creation of the vascular access (e.g. peritonitis, graft failure), or complications resulting from the ongoing presence of the catheter or type of vascular access (e.g. infection, fistula thrombosis).

Renal dialysis patients are at an increased risk of sudden cardiac death (commonest cause of which is hyperkalaemia), cardiovascular disease, and renal cell carcinoma ^2,3.