b. Methods of Dialysis. Two methods of dialysis presently in use are
hemodialysis and peritoneal dialysis. Both methods are based on the principle of
diffusion of dissolved molecules through a semipermeable membrane.
(1) Hemodialysis. In this method, a sheet of cellophane functions as the
semipermeable membrane in the dialyzer machine. A patient using this method must
usually have dialysis two or three times a week. The process is as follows:
(a) Blood leaves the body through an artery.
(b) This arterial blood passes through the machine's blood pump.
Blood is filtered to remove any clots.
(d) Blood passes through the dialyzer machine.
(e) The blood passes into the venous blood line.
Blood is filtered again to remove any clots.
(g) The blood then flows through an air detector.
(h) Finally, the blood returns to the patient through the venous blood
(2) Peritoneal dialysis. In this method of dialysis, the peritoneum acts as the
filtering membrane. Dialyzing fluid is introduced into the peritoneal cavity at intervals.
The peritoneum is a large surface area and acts as the diffusing membrane filtering the
blood in the peritoneal blood vessels. The dialyzing solution remains in the peritoneal
cavity for 15 to 30 minutes. Then the solution is allowed to drain out. The severity of
the patient's condition determines the length of time the dialysis process takes. Time
varies from 12 to 36 hours. Those patients with chronic renal disease can learn how to
do their own dialysis treatments at home. This permits patients to resume most of their