The concept of dialysis is defined as the movement of solutes across a semipermeable membrane. During dialysis, solute transport occurs by passive diffusion, i.e., solute moves from an area of high concentration to low concentration. Water, on the other hand, moves from low to high concentration. Thus, the dialysing solution must be more concentrated than the blood for water removal. Two types of dialysis are employed clinically.
Peritoneal dialysis is the most simple and frequently used form of dialysis.
The lining of the peritoneal cavity serves as a dialysis membrane. A dialysis catheter is placed in the peritoneal cavity, the dialysis fluid is injected into the cavity through this catheter and left for approximately 30 min to allow solute diffusion from the blood into the dialysis fluid. The catheter is then removed and drained. This procedure is repeated hourly for 36-48 hr. 2. Hemodialysis requires the pumping of blood through an artificial kidney, which is actually a dialyzer with a membrane for solute removal.