When is it needed? When a person's kidneys fail, also known as renal failure, they may need dialysis treatments to stay alive. Dialysis is a life-saving procedure that cleans the blood of toxins and removes excess fluid from the body. But first, the filtering system needs "access" to the person's bloodstream.
Through this access (or entryway), a portion of a person's blood is removed and circulates through the dialysis machine, which removes impurities and regulates fluid and chemical balances. The purified blood then returns to the person, again through the dialysis access.
What happens? There are four ways to create dialysis access. These access options lie completely beneath the skin, and are created through a minor surgical procedure.
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A catheter( 脖子血管進口,到達心髒.易感染,所以短期使用) , a long soft tube, is inserted in the large vein either in the neck or under the collarbone. This is usually a short-term choice, because the catheter gets infected easily, and causes stenosis (narrowing).
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An arterivenous graft is created by connecting a vein to an artery with a soft plastic tube (graft). Dialysis is performed by placing two needles in the graft.
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An arterivenous fistula is considered an excellent long-term option. The surgeon creates the fistula–which is a surgically created passageway–by connecting an artery directly to a vein. Once the connection (fistula) gets bigger and stronger (matures), it can be used for dialysis for years with almost no risk of infection. However, not every patient is a good candidate for this type of access.
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Peritoneal dialysis (PD) is another option for patients who can't tolerate the rapid changes of fluid balance associated with hemodialysis. During hemodialysis, your blood is pumped into a machine to be filtered and then returned to your body (abdominal cavity). A catheter is surgically inserted into the abdomen on a permanent basis allowing the blood vessels in the abdominal lining (peritoneum) to fill in for the kidneys, with the help of a fluid (dialysate) that flows into and out of the peritoneal space. Risks associated with peritoneal dialysis include infections, weight gain and hernia.
http://www.wehealny.org/services/vascular_surgery/kidneyconditions.html
