hemodialysis /he·mo·di·al·y·sis/ (-di-al´ĭ-sis) removal of certain elements from the blood by virtue of the difference in rates of their diffusion through a semipermeable membrane while being circulated outside the body; the process involves both diffusion and ultrafiltration.
Hemodialysis
hemodialysis
hemodialysis,
hemodialysis (hē´mōdīal´isis),
hemodialysis
he·mo·di·al·y·sis (h  m -d - l  -ss)n. A procedure for removing metabolic waste products or toxic substances from the bloodstream by dialysis. |
Hemodialysis
A method of mechanically cleansing the blood outside of the body, in order to remove various substances that would normally be cleared by the kidneys. Hemodialysis is used when an individual is in relative, or complete, kidney failure.
hemodialysis
[hē′mōdī·al′isis, hem′-]
Etymology: Gk, haima + dia, apart, lysis, loosening
a procedure in which impurities or wastes are removed from the blood, used in treating patients with renal failure and various toxic conditions. The patient's blood is shunted from the body through a machine for diffusion and ultrafiltration and then returned to the patient's circulation. Hemodialysis requires access to the patient's bloodstream, a mechanism for the transport of the blood to and from the dialyzer, and a dialyzer. Also spelled haemodialysis. See arteriovenous fistula, external shunt.
method Access may be achieved by an external shunt or an arteriovenous fistula. The external shunt is constructed by inserting two cannulas through the skin into a large vein and a large artery. When hemodialysis is not being performed, the cannulas are joined, allowing the blood to flow from artery to vein. When hemodialysis is being performed, the cannulas are separated, allowing the arterial blood to flow to the dialyzer and the dialyzed blood to return from the dialyzer to the circulation through the cannula in the vein. An arteriovenous fistula is created by the anastomosis of a large vein to an artery. Large-bore needles are threaded into superficial vessels enlarged by the increased flow caused by the fistula. Various dialyzers may be used. Hemodialysis takes from 3 to 8 hours depending on the patient's condition, weight, and laboratory values and may be necessary daily in acute conditions or two to three times a week in chronic renal failure.
interventions A decrease in blood flow through the shunt may cause clotting. Therefore any factor that may result in a slowing of the flow should be avoided. Some of these factors are systemic hypotension, infection of the shunt or fistula, compression of the shunt or fistula, thrombophlebitis, and prolonged inflation of a blood pressure cuff. Infection is prevented in the area around an external shunt by placing a sterile dressing over the shunt and changing the dressing daily. Before the procedure is begun, the patient is told how long it will take, what pain or discomfort may be expected, what will be felt afterward, what food or activity will be allowed during the procedure, and whether family or friends may be present during treatment. Headache, nausea, and muscle cramps are common, especially during the procedure and for a few hours afterward. The patient usually feels best on the day after hemodialysis. Rest, an antiemetic, and a mild analgesic may make the procedure more comfortable. Most patients need emotional support and some physical assistance during hemodialysis. The physical status of the patient is monitored frequently throughout. Blood pressure, pulse, and blood tests for electrolyte and acid-base balance are performed. Normal saline solution may be administered to counteract hypotension that results from rapid removal of fluid from the intravascular compartment. The patient is weighed before and after the treatment to determine the amount of fluid lost during the procedure. An anticoagulant is usually given to prevent coagulation of the blood in the dialyzer, cannulas, or catheters. To prevent hemorrhage, protamine sulfate may be administered after the procedure to reverse the effect of the anticoagulant. Any treatment that causes tissue trauma, such as dental extraction, venipuncture, or intramuscular injection, is not recommended during or immediately after dialysis.
outcome criteria Infection and clotting of the shunt and erosion of the skin around the shunt are frequent complications with an external shunt; therefore the method that uses an arteriovenous fistula is more common. The discomfort before, during, and just after dialysis; the prolonged time of relative immobility during the procedure; and the dietary restrictions necessary in renal insufficiency all cause considerable stress in the patient. Adjustments in the patterns of daily life are necessary and require the assistance of professionals with experience and training.
hemodialysis,
n mechanical process for removing waste products and impurities from the blood. Blood is drawn out and filtered through a dialysis machine and then reinfused. Often used in patients suffering from renal failure as well as other toxic blood conditions.
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Hemodialysis.
hemodialysis (hē´mōdīal´isis),
n a procedure in which impurities or wastes are removed from the blood. The patient's blood is shunted from the body through a machine for diffusion and ultrafiltration and returned to the patient's circulation. This procedure is used in treating renal failure and various toxic conditions. Without this, toxic wastes build up in the blood and tissues and cannot be filtered out by the ailing kidneys. This condition is known as uremia, which means “urine in the blood.” Eventually, this waste buildup leads to death. Dental treatment should occur within 24 hours of hemodialysis. See also kidney failure.
hemodialysis
removal of certain elements from the blood by virtue of difference in rates of their diffusion through a semipermeable membrane while the blood is being circulated outside the body. The procedure is used to remove toxic wastes from the blood of a patient with acute or chronic renal failure. See also kidney.
hemodialysis
Nephrology A therapeutic procedure for removing low-molecular-weight toxins by allowing the blood to flow past a semipermeable membrane where the toxins diffuse away from the blood down a concentration gradient, either via
an external AV shunt, or a surgically-placed AV fistula; hemodialysis is used in renal failure to ↓ BUN, creatinine, hyperkalemia and correct metabolic acidosis; prolonged dialysis results in a poor quality of life–anemia, infections,
myalgia, peripheral neuropathy, cerebral edema, acute MI, aluminum toxicity, ergo renal transplants are always preferred to long-term hemodialysis Complications Pyogenic reactions due to gram-negative endotoxemia, with chills, fever, hypotension,
nausea and myalgia, ↓ NK cell activity, ↓ serum calcitriol. See Dialysis dementia. Cf Hemapheresis.
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