Finding out that you have kidney disease can be difficult and understanding your kidneys is the first step in taking control of your health. Following a kidney-friendly diet, taking good care of diabetes, hypertension and other health conditions and not smoking may help your kidneys function better and longer, even when you have kidney disease. It is also important to realize that you are not alone. DaVita has a caring, compassionate and well- educated team to help you understand kidney disease and the right treatment option for you.
Hemodialysis is an effective treatment for those with end stage renal disease. However, hemodialysis alone will not provide a complete treatment for those with kidney failure. Diet and fluid restrictions need to be followed, and medicines may need to be taken to replace other functions of the kidneys, such as regulating blood pressure and stimulating production of red blood cells to prevent anemia.
In hemodialysis, blood is removed from the body and filtered through a man-made membrane called a dialyzer, or artificial kidney, and then the filtered blood is returned to the body. The average person has 4 to 5 liters of blood; during dialysis only ½ liter (about two cups) is outside of the body at a time.
To perform hemodialysis an access must be created to get the blood from the body to the dialyzer and back to the body. There are three access types for hemodialysis: arteriovenous (AV) fistula, AV graft and central venous catheter. The AV fistula is the vascular access most recommended by the dialysis community; however, you and your nephrologist will decide which access is best for you.
When a patient goes to hemodialysis, a nurse will check vital signs and get the patient’s weight. The weight gain will tell how much excess fluid the patient has to have removed during the treatment.
Patients with a vascular access (AV fistula or AV graft) will get two needle sticks in their access; one needle takes blood out of the body, the other needle puts it back. Patients with a central venous catheter will have the two tubes from their access connected to tubes that lead to the dialyzer and back to the body.
The dialysis machine is programmed and then treatment begins.
The dialysis machine is like a big computer and a pump. It keeps continuous track of blood flow, blood pressure, how much fluid is removed and other vital information. It mixes the dialysate, or dialysis solution, which is the fluid bath that goes into the dialyzer.
The dialysis machine has a blood pump that keeps the blood flowing by creating a pumping action on the blood tubes that carry the blood from the body to the dialyzer and back to the body. The dialysis machine also has many safety detection features to ensure a safe and efficient treatment.
The dialyzer is the key to hemodialysis. The dialyzer is called the artificial kidney because it filters the blood — a job the kidneys used to do. The dialyzer is a hollow plastic tube that contains many tiny filters.
Dialyzers are made in different sizes so doctors can prescribe the best one for their patients. There are two sections in the dialyzer; the section for dialysate and the section for the blood. The two sections are divided by a semipermeable membrane so that they don’t mix together.
A semipermeable membrane has microscopic holes that allow only some substances to cross the membrane. Because it is semipermeable, the membrane allows water and waste to pass through, but does not allow blood cells to pass through.
Dialysate, also called dialysis fluid, dialysis solution or bath, is a solution of pure water, electrolytes and salts, such as bicarbonate and sodium. The purpose of dialysate is to pull toxins from the blood into the dialysate. The way this works is through a process called diffusion. In the blood of the hemodialysis patient, there is a high concentration of waste, while the dialysate has a low concentration of waste. Due to the difference in concentration, the waste will move through the semipermeable membrane to create an equal amount on both sides. The dialysis solution is then flushed down the drain along with the waste. The electrolytes in the dialysis solution are also used to balance the electrolytes in the patient’s blood. There are different types of dialysis fluid so your doctor can choose the best for your treatment.
The extra fluid is removed through a process called filtration. The fluid is pushed off by higher pressure on the blood side than on the dialysate side.
Blood needs to flow through the dialyzer for several hours to adequately clean the blood and rid the body of excess fluid. Traditional, in-center hemodialysis is generally done three times a week for three to five hours per session, but most common is four hours. Talk to your nephrologist about how long your hemodialysis sessions should last.
Alternatively to daily hemodialysis schedules, you have nocturnal hemodialysis. With nocturnal hemodialysis, the patient has dialysis three times a week for about six or eight hours overnight while sleeping. This is a longer, gentler treatment so patients say they have fewer problems with cramping and the “washed out” feeling reported after traditional hemodialysis. More dialysis centers are beginning to offer in-center nocturnal hemodialysis based on reports of patients feeling better about their quality of life and having good lab results.
Talk to your nephrologist if you interested in-center nocturnal dialysis.
Hemodiafiltration (HDF) is an alternative blood purification process that removes larger uremic toxins than those that are removed from hemodialysis.
In this process, blood is pumped through a dialyzer at a high rate, causing a significant amount of uremic plasma water (a component of the uremic blood being purified) to be forced across the membrane, removing large, slow diffusing toxins from the blood. As in hemodialysis, differences in concentration between the dialysis solution and the blood are also used to filter the toxins from the blood, but in hemodiafiltration we have an infusion of purified or sterile substitution fluid back into the blood to replace the flow of uremic plasma water that was pushed across the membrane. Hemodiafiltration is used based on its effective removal of both large and small solutes.
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