One of my patients last time was a 50's-year-old female with peritonitis. In renal failure, she depended on peritoneal dialysis to do the job that properly- functioning kidneys perform. About five times a day, people hook up tubes to ports in their abdomens, draining 2000-2500cc's of dirty urine-like fluid. Then they switch clamps, or turn a dial, and a fresh volume of clean dialysis fluid enters their abdomen. Throughout the next several hours, toxins in the blood cross the peritoneum, using the inside of the abdomen as one huge reservoir where osmotic and diffusion gradients force metabolic waste. The whole process repeats throughout the day.
Some of these patients hook themselves up to "cyclers" during the night. This is a machine that periodically fills/drains the abdomen, so that the patient can get several hours of rest, without worrying about draining/filling.
Filled with dialysate, their abdomens are distended, sometimes so much so that they can't comfortably sit upright.
Susceptible to infection, many patients suffer from repeated cases of peritonitis, causing significant abdominal pain.
Due to the selective permeability of the peritoneum, the concentration of the dialysis fluid may have to be altered, based on the blood pressure of the patient. Thus, if the blood pressure is low, a lower concentration is used, such that fluid flows into the body, providing volume. If the BP is high, the patient switches to a more concentrated dialysis fluid so that fluid is pulled out of the body, lowering blood volume and blood pressure.
Amost invariably, the patient will eventually have to switch from peritoneal dialysis to hemodialysis (where blood is directly forced through a filter, removing toxins). Thus unable to dialyze themselves at home, they will have to make arrangements to get to a hemodialysis center daily or every-other-day for the remainder of their lives.