Many people use the terms ocean and sea interchangeably when speaking about the ocean, but there is a difference between the two terms when speaking of geography (the study of the Earth's surface).
The peritoneal dialysis catheter is composed of a flexible silicone tube with an open-end port and several side holes to provide optimal drainage and absorption of the dialysate. The extraperitoneal component of the catheter has either one or two Dacron cuffs. The Dacron cuffs are for optimal ingrowth and fixation.
The other type of treatment, peritoneal dialysis, uses the patient's own peritoneal membrane as a filter. The peritoneal membrane is a sac around the abdominal organs. This membrane (like the dialysis machine membrane) is semipermeable. Waste particles can get through it, but larger blood cells cannot.