Unlike Hemodialysis, which involves an external artificial kidney, peritoneal dialysis involves the blood being cleaned inside the body. The two big kinds of peritoneal dialysis are continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). CAPD does not require a machine. A bag of dialysate is inserted into the peritoneal cavity through a catheter. It stays there for four to five hours and then thrown away. This is done around four or five times a day. The APD is the automated version of the CAPD except the cycles last for an hour to an hour and a half.