Definition

Dialysis refers to the artificial cleaning of blood and provides a substitute for the kidneys, without performing all renal functions. Dialysis is typically required as a end-result of Chronic Kidney Disease.

Types of Dialysis

Haemodialysis

Haemodialysis has approximately 75% usage in Australia and is the process of pumping blood out of the body and through an external artificial kidney to receive filtration. Haemodialysis requires vascular access, which is typically achieved by:

• Fistula: Vein and artery surgically joined.
• Graft: Vein and artery too small to join, so a small tube is inserted to make connection.
• Central Venous Catheter: Catheter placed into large chest vein. Often only a temporary solution whilst awaiting fistula.

Treatment is usually 3x per week with each session lasting approximately 4 – 5 hours. Treatment involves circulating blood across a semipermeable membrane; to achieve hydrostatic pressure (like that found in the nephron) and enhance filtration, dialysate is run in counter current flow to blood.

Peritoneal Dialysis

Peritoneal Dialysis is used approximately 25% of the time in Australia and is described as the process of adding specialised fluid (dialysate) to the peritoneal cavity to provide blood filtration.

There are 2x types of peritoneal dialysis:

• Automated Peritoneal Dialysis (APD)
  • Operates while patient is asleep and requires approximately 10 – 15L of dialysate. Each machine is programed to control volume requirement for individual needs.
• Continuous Ambulatory Peritoneal Dialysis (CAPD)
  • Used approximately 4x throughout the day, taking 30 – 40 mins each session. This method is used less commonly than APD.