Dialysis

BOX 38-3 Dialysis Dialysis is the process of removing waste products and excess fluids from the body. Hemodialysis is the use of an artificial kid- ney machine to perform the functions of the nephrons of the patient’s kidneys. The patient's blood is passed through tiny tubules surrounded by fluid (dialysate), which has the same chemical composition as blood plasma. Waste products and excess fluids pass out of the patient's blood into the fluid of the machine. They are thus eliminated, and purified blood is returned to the patient. Hemodialysis must be repeated on aver— age three times per week. To achieve this goal, easy access to the patient’s bloodstream is necessary. This may be accomplished by a number of means such as creating an arteriovenous fistula or creating a synthetic graft between an artery and vein. Either type of access requires a surgical procedure. Because of the tendency of the blood to clot, heparin is administered during hemodialysis. Peritoneal dialysis involves the use of the peritoneum, the membrane that lines the abdomen and covers the abdominal organs, to function as a filter for dialysis (Figure 38—13). The peritoneum has a large surface and rich blood supply making filtration easier. Dialysate is put into the abdominal cavity through a catheter and left for a period of time (hours or overnight) to allow waste and excess fluids to be removed from the bloodstream, and then the filtrate is drained out and discarded. Several types of peritoneal dialysis are avail, able; however, each requires varying amounts of time rang— ing from 10 to 12 hours overnight, or every 3 to 4 hours four times a day. A catheter may be placed in the abdominal wall temporarily or permanently as needed. Choosing the type of dialysis depends on many factors such as age. physical condition, type of renal disorder, and lifestyle. Either type of dialysis restricts a patient’s life in terms of loss of time, specialized diet, loss of mobility, and loss of independence. In children, renal disease may stunt their growth and cause feelings of isolation.