Hemodialysis is the most common method used to treat acute and permanent kidney failure. Since the 1960s, when hemodialysis first became a practical treatment for kidney failure, much has been learned about how to make hemodialysis treatments more effective and how to minimize side effects. Over the years dialysis machines have become more compact and minimize the amount of blood held in the machine. Even with better procedures and equipment, hemodialysis is still a complicated therapy which requires a coordinated effort from your whole health care team, including your nephrologist, dialysis nurse, dialysis technician, dietitian, and the patient. By learning about dialysis treatment, the patient can work with their health care team to achieve the best possible results.

Kidney Structure and Function

The kidneys are about the size of a fist and are located starting at the bottom rib and below the ribs near the center of the back. The kidneys play a vital role in maintaining homeostasis throughout the body. They are the main organs used to remove wastes and excess water from the blood that would otherwise harm the body. The wastes and excess water removed are excreted as urine. Two healthy kidneys excrete between 1.5 and 2.5 L of urine daily and a little more than 20% of the total blood pumped by the heart each minute enters the kidneys.

The kidney is surrounded by a membrane known as the renal capsule. Once inside the renal capsule there are two main regions called the renal cortex (outer section) and the renal medulla (inner section). Blood enters the kidney through the renal artery and exits the kidney through the renal vein. Figure 1 shows a slice frontal section of the right kidney and the different sections of the kidney.

There are more than one million nephrons in each kidney functioning as the kidneys filter units. They filter unwanted material from the blood and regulate the amount of water and chemicals in the body. As blood flows through a glomerular tuft (where water and chemicals filter into the nephrons) fluid is forced into the Bowman’s capsule. The Bowman’s capsule is the expanded beginning of the tubule and acts as the nephrons collecting cup for fluid filtering from the blood. The filtrate then flows along the coil tubule and more waste material is secreted directly into the nephron tubule. At the same time, reabsorption of essential materials into the capillaries takes place. The loop of Henle acts as the primary reabsorption area. Urine, the yellowish liquid remaining, passes from the nephron collecting ducts, into the renal pelvis, which acts as a funnel to conduct the liquid into the ureter. Through the ureters the urine is conducted away from the kidney and emptied into the bladder. The cortex houses the glomerulates of each nephron and the medulla contains the loops of Henle and the collecting ducts.

The kidneys do some important jobs to keep the body healthy. These jobs can be summarized into five categories:

1. Water Balance – Keeps the amount of water entering the body equal to the amount of water leaving the body as urine.

2. Waste Removal – Removes waste products from plasma.

3. Maintain Electrolytic Balance – Keeps the body’s ionic balance normal to maintain normal cellular function.

4. Maintains Acid-Base Balance – As the body breaks down proteins acids are created. The kidneys excrete hydrogen atoms and produce bicarbonate which in conjunction with water, hydrogen ions, and carbon dioxide forms a buffering system which is maintained at the volatile equilibrium required to provide prompt resistance to drastic pH changes in both the acidic and basic directions. This is especially important for protecting tissues of the central nervous system, where pH changes too far outside of the normal range in either direction could prove disastrous (acidosis and alkolosis).

5. Hormone Production – Release hormones into your blood to control blood pressure, make red blood cells, and keep your bones healthy.

Effects of Chronic Kidney Disease

Kidney failure occurs when the kidneys partly or completely lose their ability to filter water and waste from the blood. Kidney failure can be put into two classes, acute and chronic kidney failure. Acute failure is the sudden and temporary loss of kidney function usually due to an injury. Chronic failure results when a disease slowly destroys your kidneys. Destruction occurs over many years, usually with no symptoms until the late stage of kidney failure. Progression may be so gradual that symptoms may not occur until kidney function is less than 10-15% of normal. As kidney function decreases, the symptoms are related to the inability to regulate water and electrolyte balances, the inability to remove waste products from the body, and the inability to promote red blood cell production. Some of the symptoms of kidney failure include:

  1. Anemia

Anemia is a condition in which you don't have enough healthy red blood cells to carry adequate oxygen to your tissues. This happens because the diseased kidneys do not make sufficient amounts of a hormone called erythropoietin, or EPO, which stimulates the bone marrow to make red blood cells. This results in a decreased supply of red blood cells to carry oxygen to all the cells in the body. The lack of oxygen results in shortness of breath, fatigue, weakness, fainting, and a pale skin complexion.

2. Bone Disease The kidneys play an important role in balancing the hormones calcium and phosphorous. When the kidneys are not working well, they do not get rid of enough phosphorus from the body through the urine. When the phosphorus level in the blood becomes too high, calcium is lost from the bones, resulting in weakening of the bones over time. Bone disease causes no outward signs in the early stages. Gradually, over time, pain may occur in bones and joints and fractures happen more easily.

3. Peripheral Nerve Damage This includes a variety of nerve-related problems that can occur with chronic kidney disease and kidney failure. Typical symptoms are pain, weakness, or a feeling of numbness in the feet, legs, and hands, a burning feeling in the feet, a feeling of discomfort and restlessness in the legs and feet.

4. High Blood Pressure Healthy kidneys control how much salt and water is retained or eliminated from your body. Kidney failure has an enormous impact on blood pressure because the kidneys are no longer able to maintain the right balance of fluids in the body.\

Treatment Options for Kidney Failure

Once chronic kidney disease progresses until 85-90% or more of total kidney function is lost, patients will need long-term dialysis treatments or a kidney transplant to replace the function of the kidneys. The transplantation process begins when you learn that your kidneys are failing and you must start to consider your treatment options. Whether transplantation is to be among your options will depend on your specific situation. Transplantation isn’t for everyone. Your doctor may tell you that you have a condition that would make transplantation dangerous or unlikely to succeed. Figure 2 shows how a transplanted kidney may be placed in the body.

Dialysis may be the chosen for treating kidney failure while waiting for a transplant of if a kidney transplant has been ruled out as a viable option. Dialysis cleanses the body of waste products in the body by use of filter systems. The two types of dialysis are hemodialysis and peritoneal dialysis.

During peritoneal dialysis a soft tube called a catheter is used to fill the abdomen with a cleansing liquid called dialysis solution. The walls of the abdominal cavity are lined with a membrane called the peritoneum, which allows waste products and extra fluid to pass from the blood into the dialysis solution. The solution contains a sugar called dextrose that will pull wastes and extra fluid into the abdominal cavity. These wastes and fluid then leave the body when the dialysis solution is drained. The used solution, containing wastes and extra fluid, is then thrown away. The process of draining and filling is called an exchange and takes about 30 to 40 minutes. The period the dialysis solution is in the abdomen is called the dwell time. A typical schedule calls for four exchanges a day, each with a dwell time of 4 to 6 hours.

During peritoneal dialysis the body’s natural membrane of the abdomen is used and during hemodialysis a man-made membrane is used. For hemodialysis, the patient is connected to a filter (dialyzer) by tubes attached to blood vessels. Blood is slowly pumped from the body into the dialyzer, where waste products and extra fluid are removed. The filtered blood is then pumped back into the body.

The Gambro Phoenix dialysis system has become one of the most common units used in hemodialysis due to its standard in patient safety and operational efficiencies. Designed with a unique protective blood module, Phoenix system eliminates the risk of cross-contamination between patients caused by transducer protector contamination. The low-volume design of the Gambro Cartridge Blood Set also offers optimal biocompatibility and allows for a minimal amount of blood to be out of the patient at one time.The combined use of BiCart Cartridge and Diaclear Ultrafilter reduces bacteria and endotoxins, resulting in fewer dialysis related problems for your patients.

Other features:

Ø Diascan Monitoring System offers real-time evaluation of dialysis efficiency.

Ø System automations – including auto-prime, programmable recirculation, auto-disinfection and rinse, automatic wake-up and auto-off functions – streamline workflow for optimal efficiency.

Ø Intelligent design set-up eliminates the need for dialyzer rotation and the need for a waste-priming bucket.

Ø Reduced downtimes minimize time to treatment and time between two treatments to less than 10 minutes, and 32 minutes for full chemical disinfection.

The kidneys play a vital role in maintaining life. Without the kidneys the body’s toxin levels will rise to extraordinary levels ultimately resulting in death from poison. In order to prevent kidney failure it is important to adhere to a diet that will not overwork the kidneys. An overworked kidney, just like an overworked person, will burn out sooner. Also, it is important to get regular examinations by a physician to check for diabetes and hypertension, which are the two main causes for kidney deterioration.

Works Cited

"Treatment Methods for Kidney Failure: Hemodialysis." The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Available from Internet; accessed 14 May 2010.

"Treatment Methods for Kidney Failure: Transplantation." The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Available from Internet; accessed 14 May 2010.

"Treatment Methods for Kidney Failure: Peritoneal dialysis." The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Available from Internet; accessed 14 May 2010.

"Kidney Function, Chronic Renal Failure, and Its Treatment." American Regent. Available from Internet; accessed 14 May 2010.

"Anatomy of a Kidney." Youtube. Available from Internet; accessed 14 May 2010.

"An Introduction to the Kidneys and Chronic Kidney Disease." National Kidney Foundation. Available from Internet; accessed 14 May 2010.