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Hemodialysis and peritoneal dialysis are both treatment methods of filtering wastes from the body because the kidneys are no longer able to do so. One general difference between hemodialysis and peritoneal dialysis is that hemodialysis is for those who still have some kidney function left, and peritoneal dialysis is for those who actually have kidney failure and are waiting for a kidney transplant. Another general difference between hemodialysis and peritoneal dialysis is that in hemodialysis, the filtration of wastes occurs in a machine, while in peritoneal dialysis, the filtration occurs within the abdomen.
Basically, in hemodialysis, blood leaves the body, gets filtered by a machine called a dialyzer, and then returns to the body. The patient has two needles inserted into an access site on his arm, with one needle for blood leaving the body and the other for blood re-entering the body. The dialyzer performs the filtration process several ounces or grams at a time. While undergoing the treatment, the patient sits in a chair and is able to conduct activities such as napping or reading.
A person who receives hemodialysis has the procedure done at a dialysis center, in a hospital or even at home. There are two different types of hemodialysis procedures: conventional and daily. Conventional hemodialysis is when the patient undergoes the procedure about three times a week, each session lasting between three to five hours. Daily hemodialysis is when the patient undergoes the procedure about six or seven days a week, with each session lasting about two to three hours. For those who want flexibility with their hemodialysis treatments, smaller machines enable them to receive treatments at home on their own time, even while they sleep.
In peritoneal dialysis, a solution called dialysate filters wastes in the abdomen and then drains into a collection bag. The solution enters the abdomen through a catheter and stays there for a certain length of time; this time is called the dwell time. During dwell time, wastes in the blood pass from blood vessels in the abdominal lining and into the solution. After dwell time, the solution and waste drain into a collection bag, which the patient then empties. The entire process of filling the abdomen and draining it is called exchange.
If he is strong enough, a person who undergoes peritoneal dialysis can administer the treatment himself at home, during travel, or at work. In general, there are two main types of peritoneal dialysis procedures: continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD). CAPD involves three to five exchanges throughout the day and one longer dwell time during the night while the patient sleeps. CCPD is, in general, the opposite and involves three to five exchanges at nighttime as the patient sleeps and one longer dwell time during the day.
Peritoneal dialysis is more convenient, since it is done in the home, but it has fallen out of favor in recent years because of the risk of infection, and doctors feel it is not as effective as hemodialysis. It is more common in third world countries where access to dialysis units is more restricted.
Another factor in using PD is monitoring how much fluid is pulled off, and how much weight the patient gains or loses after and in between treatments. An accurate scale is a must and the patient or helper must be able to determine which solution to use for the next dialysis session in order to get the best results without pulling too much fluid. It's a delicate balance.