What is Dialysis? All You Need to Know

What is Dialysis?

One of the most important functions of the kidneys is to remove waste and toxins from the body due to various reasons. In addition, it also serves to maintain water and mineral balance. It removes waste, excess water and minerals from the body as urine. These functions cannot be fulfilled in people whose kidneys do not function properly and adequately. Waste and minerals that cannot be eliminated begin to accumulate in the body. The most appropriate treatment for these patients is dialysis treatment. Because dialysis is an artificial system that fulfills the natural function of the kidney. It is also called “renal replacement therapy” because it performs the excretion process instead of the kidney.

The function of the kidneys is not limited to excretion. Kidneys also have functions of secreting important hormones and substances. The kidneys secrete hormones such as erythropoietin and renin. It plays a role in the activation of vitamin D. In case of chronic kidney disease, this function of the kidney cannot be fulfilled. However, although dialysis is called renal replacement therapy, it cannot fulfill the secretory function of the kidney.

Dialysis Types

There are special treatment centers and areas for dialysis. These places are called dialysis centers. There are two basic dialysis methods for chronic kidney patients: hemodialysis and peritoneal dialysis. CRRT dialysis, known as continuous renal replacement therapy, is mostly used for intensive care patients who develop acute renal failure; Also known as hemofiltration. Hemofiltration is performed 12-24 hours a day, every day of the week.

The most common dialysis method is hemodialysis. An artificial device called “hemodialyzer” is used to remove waste and excess water from the body. Blood enters the hemodialyzer from the body, after the hemodialyzer filters the blood, it is returned to the body. Vascular access is needed to provide this blood flow between the hemodialyzer device and the body. 

There are 3 types of vascular access:

1. Arteriovenous (AV) fistula: It is the most preferred vascular access. The artery and vein are surgically connected together.
2. Arteriovenous graft: A tube that connects the artery and vein is used.
3. Dialysis catheter: Also known as central venous catheter. Most often, a large vein in the neck is selected. 

AV fistula and AV graft methods should be preferred for dialysis patients who receive dialysis treatment for a long time. People who have had AV fistula surgery can undergo dialysis using the fistula 2-3 months after the fistula. Patients using AV grafts can enter dialysis using the graft 2-3 weeks after the graft is placed. Dialysis catheters are suitable for short-term use. Generally, AV fistula is opened for dialysis patients to undergo dialysis during the 2-3 month period when they cannot use the fistula.
Hemodialysis sessions last 3-5 hours and are performed three times a week. It can also be completed in shorter sessions 4-5 times a week. Factors affecting the duration of hemodialysis sessions; body size, the amount of waste accumulated in the body and the general health condition of the patient before the session.

In order to perform peritoneal dialysis, a peritoneal dialysis catheter is surgically placed in the abdomen of the dialysis patient. The biggest difference from hemodialysis is that the membrane used to filter the blood is not an artificial device but its own abdominal membrane (peritoneum). During the treatment, a special liquid called “dialysate” is sent to the peritoneum. Dialysis fluid absorbs waste. After collecting waste from the bloodstream, dialysate is withdrawn from the abdominal cavity. Peritoneal dialysis takes several hours and needs to be done 4-6 times a day. Its biggest advantage is that it can be done while the patient is asleep or awake. 

How is Dialysis Done?

Dialysis machines consist of a special fluid called dialysate and a series of membranes to clean the blood. Waste substances in the dialysis patient’s blood are filtered through membranes. Waste substances pass into the dialysate fluid. While the dialysate fluid, which contains waste materials, is pumped out of the dialysis machine, the filtered blood is returned to the patient’s body. Dialysis is not a painful procedure, but the patient may experience dizziness and muscle cramps during the procedure. Side effects after dialysis can be listed as hypotension, muscle cramps, clot formation, infection, weight gain and itching.

Who Should Receive Dialysis Treatment?

Kidney failure is generally classified under two subheadings: acute and chronic kidney failure. While kidney failure that develops suddenly is called acute, when the kidney gradually becomes damaged and fails in the long term, it is called chronic. People with chronic kidney disease or end-stage renal disease (ESRD) need dialysis. Diseases such as hypertension, diabetes or lupus can damage the kidneys in the long term. However, in some people, the causes of chronic kidney failure cannot be identified. Chronic kidney disease is examined in five stages. The fifth stage is called end-stage renal disease (ESRD). At this point, the kidneys can only perform 10 to 15% of their normal functions. At this stage, patients either need renal replacement therapy such as dialysis or they need a kidney transplant. Patients awaiting transplantation also need dialysis during this period. The last stage of dialysis patients requires kidney transplantation. When making the decision for dialysis, the patient’s symptoms as well as kidney functions are taken into consideration. One of the most important findings of chronic kidney diseases is edema. Water accumulation in the lungs in dialysis patients is also related to edema and excess water retained in the body.

Frequently Asked Questions About Dialysis

Dialysis treatment is required when the patient’s kidneys can no longer handle the body’s waste and water load on their own. This happens when end-stage renal disease develops. When the kidneys fulfill only 10-15% of their functions, the patient no longer needs dialysis treatment. Glomerular filtration rate (GFR) is less than 15 ml/min in the end stage.

Creatine is a waste product formed as a result of muscle metabolism. There is no definitive serum creatinine level that determines the threshold for undergoing dialysis. The decision for dialysis is made based on the patient’s symptoms and how well the kidney can function. GFR is calculated based on creatinine clearance. A decision cannot be made with serum creatinine level alone.

The normal urea level in an adult male is 8-24 mg/dl and in an adult female it is 6-21 mg/dl. There is no set urea level for dialysis. However, at abnormally high urea levels (>200 mg/dl) the patient has signs and symptoms. This may require dialysis. Again, dialysis cannot be decided by urea level alone. A comprehensive evaluation is required for the decision on dialysis.

The duration of dialysis sessions may vary depending on the amount of waste accumulated in the person’s body and the general condition of the dialysis patient. In general, hemodialysis sessions last 3-5 hours, while peritoneal dialysis takes 1-2 hours. While hemodialysis is performed 1 session a day 3 times a week, peritoneal dialysis is performed 4-6 sessions a day 5 times a week.