Kidney dialysis

Our kidneys clean our blood. They take out extra water. They also take out bad things.

Sometimes kidneys stop working well. People then need a machine to help. This is called dialysis.

The machine uses a special filter. This filter has tiny holes. The holes let bad things pass through. But the holes are too small for blood cells. This keeps the good blood inside.

The clean blood goes back to the body. This helps the person stay healthy.

Our kidneys clean our blood. They take out extra water and waste.

Sometimes, kidneys stop working well. People then need a way to clean their blood. This is called dialysis.

One way is hemodialysis. This uses a machine and a filter. We call this filter a dialyzer. The dialyzer has a semipermeable membrane. This is a thin layer with tiny holes. These holes are like a sieve. They let small waste pass through. But the holes are too small for blood cells.

In hemodialysis, blood flows through the filter. A special fluid called dialysate flows around it. Waste moves from the blood into the fluid. This movement is called diffusion. A second way is peritoneal dialysis. This happens inside the body. It uses the peritoneum, which is a natural lining in the belly. A special fluid goes into the belly. Waste moves from the blood into that fluid. This helps keep the body healthy.

Kidneys are amazing organs that keep our bodies healthy. They maintain a balance of water and minerals like sodium and calcium. They also help make red blood cells and keep bones strong. Sometimes, kidneys stop working well or stop working all at once. This is called acute kidney injury or chronic kidney failure. When this happens, toxins and extra water build up in the blood.

Dialysis is a way to help by cleaning the blood. It can be a temporary fix or a permanent way to live.

One way dialysis works is through a process called diffusion. This happens when substances move from a place with a lot of them to a place with less. In hemodialysis, blood flows through a filter called a dialyzer. Inside the dialyzer, there is a semipermeable membrane. This is a thin layer with tiny holes or pores.

The holes are big enough for waste to pass through. However, the holes are too small for large things like red blood cells. A special liquid called dialysate flows on the other side of the membrane. It pulls the waste out of the blood to clean it.

Another way to clean the blood is called peritoneal dialysis. This method happens inside the body instead of using a machine filter. It uses the peritoneum, which is a natural lining in the abdomen.

A sterile liquid called dialysate is sent into the belly area. The waste and extra water move from the blood across the peritoneum. This exchange happens several times every day. While it is less efficient than other ways, it works because it happens for a long time. Many people can do this at home without much special equipment.

Doctors and scientists have worked on these methods for a long time. The first successful dialysis was performed way back in 1943. There are also other types like hemofiltration and hemodiafiltration. Hemofiltration uses pressure to drag water and waste across a membrane. It does not use dialysate like the other ways. Instead, it uses a substitution fluid to replace what was lost.

These different tools help doctors treat many different kinds of kidney problems.

Dialysis is a very important part of modern medicine. In the United States, many people go to a center three times a week. In 2011, hemodialysis was one of the most common procedures in U.S. hospitals. It happened during about 909,000 hospital stays that year.

Some people even do their treatments at home while they sleep. This is called nocturnal daily hemodialysis. It can help people feel better by cleaning the blood more often. Learning about these machines helps us see how science helps us stay healthy.

Kidney dialysis is a vital medical process used to clean the blood. It removes excess water, toxins, and solutes when the kidneys can no longer do this naturally. This treatment is a type of renal replacement therapy. It can be used as a temporary measure for acute kidney injury, which is a sudden loss of function. It is also used for chronic kidney failure, which is a gradual decline in function.

In stage 5 chronic kidney failure, the glomerular filtration rate drops below 15% of normal. At this stage, creatinine clearance is less than 10 mL per minute, and uremia is present. Dialysis helps keep the body in balance while patients wait for a kidney transplant or as a permanent solution.

To understand dialysis, we must look at how the kidneys work. Healthy kidneys maintain the body's internal equilibrium of water and minerals. They manage levels of sodium, potassium, chloride, calcium, phosphorus, magnesium, and sulphate. They also excrete acidic metabolism end-products that the body cannot remove through breathing. Furthermore, kidneys act as part of the endocrine system. They produce erythropoietin for red blood cell production and calcitriol for bone formation.

Because dialysis cannot replace these endocrine functions, it is considered an imperfect replacement for the organ.

Dialysis relies on two main physical principles: diffusion and ultrafiltration. Diffusion is the movement of substances from an area of high concentration to an area of low concentration. In dialysis, blood flows on one side of a semipermeable membrane. A special liquid called dialysate flows on the opposite side.

A semipermeable membrane is a material with tiny pores. These pores allow small solutes and fluids to pass through. However, the membrane blocks larger substances like red blood cells and large proteins. This process mimics how the kidney's glomerulus separates small substances from large ones.

Hemodialysis is the most common primary type of dialysis. In this method, blood is pumped outside the body through an external filter called a dialyzer. The dialyzer contains thousands of tiny, hollow synthetic fibers that act as the semipermeable membrane.

To make the process more efficient, the blood and dialysate move in opposite directions. This is called counter-current flow. It maximizes the concentration gradient to help remove urea and creatinine. The dialysate contains specific levels of minerals. For example, bicarbonate levels are set slightly higher than in normal blood to help neutralize metabolic acidosis. Ultrafiltration also occurs by applying negative pressure to the dialysate compartment. This pressure gradient pulls excess water and dissolved solutes from the blood into the dialysate.

Peritoneal dialysis is another primary method that happens inside the body. Instead of an external machine, it uses the peritoneum as a natural semipermeable membrane. The peritoneum is the lining of the abdominal cavity.

A sterile dialysate containing glucose is run through a tube into the peritoneal cavity. Wastes and water move from the blood, across the visceral peritoneum, and into the dialysate. This exchange is repeated four to five times per day. While it is less efficient than hemodialysis, the long duration of the treatment results in similar waste removal. Many patients perform this at home, which offers more flexibility than visiting a clinic.

There are also specialized methods like hemofiltration and hemodiafiltration. Hemofiltration is a primary treatment that uses a pressure gradient instead of dialysate. Water moves rapidly across a very permeable membrane, "dragging" large molecular weight substances along with it. Because this process removes salts and water, a substitution fluid must be infused into the circuit to replace them.

Hemodiafiltration combines the principles of both hemodialysis and hemofiltration. It is often used to purify blood from toxins or to treat acute kidney injury.

Medical history shows how far this technology has come. The first successful dialysis was performed in 1943. In the United States, hemodialysis is a very common hospital procedure. In 2011, it accounted for 909,000 hospital stays, which was a rate of 29 stays per 10,000 people. While many patients visit centers three times a week, some practice nocturnal daily hemodialysis at home. This involves longer, more frequent treatments while sleeping. Studies show these frequent treatments can improve the clearance of molecules and decrease the need for phosphate binders.