Hemodialysis ("dialysis," for short) is a blood-cleansing procedure used as treatment for chronic kidney failure. The chief function of the kidneys is to filter waste products from the blood. When the kidneys fail, hemodialysis takes over their function. During hemodialysis, blood is removed from a vein in the patient's arm (the leg is also used, albeit much less frequently), circulated through a filtering machine, and returned to the body through an artery.
Reasons for Hemodialysis
Hemodialysis is necessary for patients who have end-stage kidney disease or permanent kidney failure. Usually, hemodialysis is required when 85 to 90 percent of kidney function has been lost. In some cases, only temporary hemodialysis is needed until kidney function returns. When treating kidney failure, however, hemodialysis is lifelong, unless the patient receives a kidney transplant. Common causes of kidney failure include the following:
- Kidney inflammation
- Blood vessel inflammation
- Polycystic kidney disease
The kidneys can also shut down suddenly after a heart attack or severe injury, or as a result of surgery.
The Hemodialysis Procedure
Because veins tend to have weak blood flow, doctors often connect one of the patient's nearby arteries to the vein being accessed for hemodialysis. This increases blood flow and strengthens the vein, which in turn allows for more blood to flow. The vein's increased strength and capacity help to create a durable access site, and provide ample blood flow for patients undergoing long-term hemodialysis.
An arteriovenous (AV) connection can be created using either a graft or fistula. A graft is an artificial tube; an AV fistula is a direct surgical connection, created by using the patient's own tissue, of an artery and a vein. Although fistulas typically take 3 to 6 months to mature while grafts take only 2 to 6 weeks, doctors prefer fistulas because they tend to be stronger than grafts, and have lower risks of infection.
Grafts may be recommended for patients with small, blocked or scarred veins. If a patient needs immediate treatment, a tube called a "venous catheter" is used for a few weeks or months until the fistula or graft is ready.
Risks of Hemodialysis
Although usually safe, hemodialysis is a complex procedure that has serious risks, including the following, associated with it:
- Muscle cramps
- Sleep problems
- Low blood pressure (hypotension)
- Bone diseases
- High blood pressure (hypertension)
- Pulmonary edema (fluid in the lungs)
- Pericarditis (inflammation of the membrane around the heart)
- High potassium levels
- Infection at the site of the incision
Joint pain and stiffness resulting from protein buildup is also a risk associated with hemodialysis.
Patient Care During Hemodialysis
While undergoing hemodialysis, it is extremely important for patients and healthcare professionals to avoid infection. Washing hands, wearing masks, using antiseptic wipes and routinely checking supplies for any signs of contamination are essential. In addition, hemodialysis patients have to carefully monitor their diets. They must make sure that their fluid intake is balanced, that they eat a diet high in protein, and that they restrict their intake of potassium- or phosphorous-rich foods such as beans, seeds and green, leafy vegetables.