• Failing kidneys may reach a point when they no longer excrete water and ions at rates that maintain body balances of these substances, nor can they excrete waste products as fast as they are produced.• An elevation of waste products, as measured in the blood, is called "azotemia." When waste products accumulate they, cause a sick feeling throughout the body called “uremia”.
• The clinical techniques used to perform the kidney’s excretory functions are hemodialysis and peritoneal dialysis.• Dialysis simply means to separate substances using a permeable membrane.• The two major blood chemical levels that are measured are the "creatinine level" and the "blood urea nitrogen" (BUN) level. As these two levels rise, they are indicators of the decreasing ability of the kidneys to cleanse the body of waste products.
• Usually, when the creatinine clearance falls to 10-12 cc/minute, the patient needs dialysis.• Hemodialysis uses a special type of filter to remove excess waste products and water from the body.• Peritoneal dialysis uses a fluid that is placed into the patients stomach cavity through a special plastic tube to remove excess waste products and fluid from the body.
• In hemodialysis, the patients blood is pumped through the blood compartment of a dialyzer, exposing it to a partially permeable membrane. The dialyzer is composed of thousands of tiny synthetic hollow fibers. The fiber wall acts as the semipermeable membrane.• Blood flows through the fibers, dialysis solution flows around the outside of the fibers, and water and wastes move between these two solutions. The cleansed blood is then returned via the circuit back to the body.
• Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This usually is done by applying a negative pressure to the dialysate compartment of the dialyzer.• This pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows the removal of several litres of excess fluid during a typical 3 to 5 hour treatment.
For example, if the plasma potassium concentration of the patient is above normal, potassuim diffuses out of the blood across the tubing and into the dialysis fluid. Similarly, waste products and excesses of other substances also diffuse into the dialysis fluid.• This type of hemodialysis is usually called "nocturnal daily hemodialysis", which has shown a significant improvement in both small and large molecular weight clearance and decrease the requirement of taking phosphate binders.
• In peritoneal dialysis, a sterile solution containing glucose is run through a tube into the peritoneal cavity, the abdominal body cavity around the intestine, where the peritoneal membrane acts as a semi permeable membrane.• The peritoneal membrane or peritoneum is a layer of tissue containing blood vessels that lines and surrounds the peritoneal, or abdominal, cavity and the internal abdominal organs (stomach, spleen, liver, and intestines)..
The dialysate is left there for a period of time to absorb waste products, and then it is drained out through the tube and discarded.This cycle or "exchange" is normally repeated4-5 times during the day, (sometimes moreoften overnight with an automated system).Each time the dialysate fills and empties fromthe abdomen is called one exchange. A dwelltime means that the time of dialysate stay inpatients abdominal cavity—wastes,chemicals and extra fluid move from patientsblood to the dialysate across the peritoneum.
• A drain process is the process after the dwell time, the dialysate full with waste products and extra fluid is drained out of patients blood.• Ultrafiltration occurs via osmosis; the dialysis solution used contains a high concentration of glucose, and the resulting osmotic pressure causes fluid to move from the blood into the dialysate.• As a result, more fluid is drained than was instilled. Peritoneal dialysis is less efficient than hemodialysis, but because it is carried out for a longer period of time the net effect in terms of removal of waste products and of salt and water are similar to hemodialysis.
• For many patients, the major advantage of hemodialysis is minimal participation in the treatment. However, patients are required to adhere to a specific schedule and travel to the dialysis unit. Hemodialysis also requires stricter diet control and fluid control than peritoneal dialysis.• The major problem with peritoneal dialysis is infection. The patient has a plastic tube that goes from the peritoneal cavity to the outside of the body and this is a potential site for the entry of bacteria into the body. Great emphasis is placed on cleanliness and technique during the training sessions.
TRANSPLANTATION• The long term treatment of choice for most patients with renal failure is kidney transplantation.• Many people who might benefit from a transplant, however, do not receive one.• It is more effective than dialysis and works ten times better. Kidneys can be donated from living persons or the deceased.
• Patients with kidney transplants are required to take medicines for life or for as long as the transplant is in the body. This medicine keeps the body from rejecting the transplant.• Before a kidney transplant can be done, the patient has to undergo several tests to determine the chances of your body accepting the available kidney.• The transplant kidney is inserted into the lower abdomen and connected to an artery and a vein. As soon as blood begins to flow through the new kidney, will be able to perform the regular functions of a kidney.
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