Introduced in the mid-forties, but became common practice since the 60s, dialysis is a procedure (therapy) to remove waste produced by the body and excess fluid from the blood when the patient's kidney function is compromised. 85-90%.

Another function of dialysis is to ensure the balance of certain substances in the blood such as, for example, potassium, sodium, calcium, phosphorus and bicarbonate.

Causes of dialysis

Normally the kidneys filter the blood by removing harmful wastes and excess fluids and convert them into urine to expel them from the body and avoid the accumulation of toxins in the blood.

If the kidneys fail, as in severe kidney failure, they are unable to clean the blood and a dangerous amount of waste and fluid builds up in the body which can cause severe discomfort and in some cases, death Dialysis filters (removes) unwanted substances and excess fluids in the blood before this happens.

Duration over time

The duration of the dialysis process over time depends on the causes that made it necessary. Renal failure, in fact, can be a temporary problem and, in this case, dialysis can be interrupted when the kidneys resume their functions. Or, it can be permanent and require kidney transplantation: in this situation, dialysis allows the patient waiting to be transplanted to continue living until a compatible donor is available.In cases where the sick person cannot undergo a kidney transplant because age or general health does not allow it, dialysis may be necessary for the rest of life.

Types of dialysis

There are two main types of dialysis, hemodialysis or extracorporeal dialysis and peritoneal dialysis or intracorporeal dialysis. In both cases it replaces the functions of the kidneys and requires:

  • blood circulation which, in extracorporeal dialysis, takes place in an external circuit; in peritoneal dialysis, on the other hand, it is constituted by the capillary circulation of the peritoneum itself. The peritoneum is a membrane, very rich in blood vessels, which lines the walls of the abdominal cavity and the organs contained within
  • the dialysis fluid which, with its composition determines, through a process called diffusion, the passage of waste and excess liquids from the blood to the liquid itself
  • a semipermeable membrane which separates the blood from the dialysis fluid and serves to retain the cells and other substances useful for the body in the blood. In extracorporeal dialysis it consists of an artificial membrane (dialysis filter); in the case of peritoneal dialysis it is the peritoneum itself which performs the function of a semipermeable membrane


In our country, hemodialysis is the best known and most widespread type of dialysis.

During the procedure, the patient is connected by means of a needle-cannula, inserted in the arm, to a circuit that sucks the blood through a pump and pushes it into the filter that allows the passage of waste from the blood to the dialysis liquid; after passing the filter, the purified blood returns to the patient's body through a second cannula needle inserted, generally, in the same arm.

In hemodialysis, the removal of liquids occurs by means of the pressure generated by the pump and, when necessary, by an additional pressure produced by the dialysis machine.

This type of procedure takes about four hours and is done three times a week.

Peritoneal dialysis

Peritoneal dialysis is a technique that involves the permanent application, in the area immediately below the navel, of a small tube (catheter) that reaches the peritoneal cavity located inside the abdomen. A liquid (dialysis fluid) is introduced through the catheter, composed of salts and glucose, which in contact with the filter constituted by the peritoneal membrane captures the waste present in the blood.

The peculiarity of this type of dialysis consists in using the internal lining of the abdomen (peritoneum) as a filter since, like the kidneys, it contains many thousands of small blood vessels.

As the blood passes through the blood vessels that line the peritoneal cavity, waste substances and excess fluids present in it are expelled and transferred to the dialysis fluid inserted into the abdomen through the catheter. The used fluid is eliminated a few hours later. inside a bag and replaced with another clean one.

Unlike "hemodialysis, in which the removal of excess fluids present in the blood is initiated by the pressure generated by the machinery, in peritoneal dialysis it is the glucose present in the fluid inserted into the abdomen through the catheter (dialysis fluid) that favors the" expulsion of excess fluids.

Changing the dialysis fluid generally takes about 30-40 minutes and, normally, the operation must be repeated four times a day. One of the advantages of peritoneal dialysis is the possibility of carrying it out during the night, while the patient is sleeping, through a special machinery.

Choice of the most suitable type of dialysis

In many cases, you can choose which type of dialysis you want to undergo.

The two techniques are equally effective for most people, but each has its advantages and disadvantages:

  • the "hemodialysis provides three treatments a week, leaving the patient free for the remaining four days. However, the procedure lasts longer and generally requires the assistance of specialized personnel
  • peritoneal dialysis it can be performed quite easily, even at home, by the patient himself or a family member and, in some cases, even during sleep. However, it must be done every day

In general, to facilitate the choice of the most suitable therapy, the patient is supported by a team of professionals (doctor, nurses, etc.) who illustrate the pros and cons of each alternative to help him make the best decision.

Side effects of dialysis

Hemodialysis can cause various unwanted disorders (side disorders) including low blood pressure (hypotension), fatigue, paraesthesia (sensitivity disorders, tingling), itching and muscle cramps.

Living on dialysis

Many people on dialysis have a good quality of life. I'm able to:

  • continue to work or study
  • travel
  • to drive
  • Playing sports

Most can remain on dialysis for many years although the procedure only partially compensates for the loss of kidney function and this can be a strain on the body.

Kidney transplant ensures better rehabilitation and a better quality of life. Unfortunately, however, during the dialysis process, while waiting for the transplant, some people die. Particularly at risk are individuals in old age and with other concomitant diseases.

The life expectancy of patients on dialysis depends a lot on age: the more advanced the years are, the lower the hopes of surviving for a long time. Thanks to the progress made in recent times, however, the survival rate is growing compared to the last decade and is expected to continue to do so in the future.

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