artificial kidney

Artificial kidney





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Hemodialysis machine.

The artificial kidney is a system that replaces the function of the kidneys in case of acute or chronic renal failure.

Healthy kidneys continuously remove toxic substances, salts and other elements that are harmful to the body. Dissolved in the water contained in the body, these substances are excreted in the form of urine. When due to illness or trauma, the two kidneys fail to perform this function for a limited time (acute renal failure), or permanently (chronic renal failure), it is necessary to replace the function of the kidneys by an artificial process called dialysis, word that means depuration, in which the patient's blood is drawn, cleaned in a machine designed for this purpose to finally return it to the bloodstream. Or by peritoneal dialysis, it uses a natural membrane - the peritoneum - as a filter. The dialysis fluid is introduced into the peritoneal cavity through a small flexible tube that was previously implanted in the abdomen permanently, in a minor surgical intervention. Part of this tube, or catheter, remains outside the abdomen. Chronic patients undergo a dialysis program, which ideally ends after a not very long time, for which it is necessary to have located an adequate kidney to be transplanted. As long as a suitable kidney is not found, the patient must follow the treatment, which today can be performed without excessive complications during a practically unlimited period of time.

The artificial kidney

Since the 1970s, artificial kidneys have been used, which have been considerably improved over the time since their appearance. Dialysis by this system is called hemodialysis (heme in Greek means "blood"). In this procedure, an external circuit is created through which the body's blood flows. Through a filter, the substances that are of interest to be removed from the body are removed, and then the blood returns to the body. After about four hours of treatment the concentration of these substances in the body has dropped sufficiently, so that the patient can return to normal life. Should return in two or three days, since to keep the body in proper conditions, it is necessary to undergo hemodialysis three times a week for about four hours each time.
Description of the artificial kidney

The artificial kidney basically consists of an apparatus, a dialyzer, a concentrated liquid, tubes for the external circulation of blood, and devices for access to blood vessels.
ApparatusEdit

It has the function of pumping the blood through the external circulation tubes, of mixing the concentrated liquid with water to obtain the adequate dilution, and of monitoring the essential constants throughout the process.
Dialyzer

It is a cylindrical container about 40 cm long, inside which there is a very high number of fine semipermeable capillaries. Blood flows through these capillaries, while the dialysis fluid, that is, the diluted concentrate, flows out. Based on the principle of diffusion and convection, the substances to be eliminated from the blood pass through these capillaries and are absorbed by the liquid. The dialyzer is thus the main element of hemodialysis, since it is the device in which the filtration of the blood takes place.
Concentrated liquid

It is supplied in a ratio of 1/35, that is, it must be diluted 35 times. Concentrated liquid is used in hemodialysis since the amount of liquid consumed in a session is very considerable. If manufacturing laboratories had to supply the diluted liquid in 1/1 proportion, or be ready for use, considerable transport and storage problems would be created. The liquid contains salts and minerals that give it the osmotic value of the body under normal conditions. In this way, by absorbing the toxins and other substances to be eliminated, the diluted liquid does not also absorb the salts and minerals that must remain in the patient's body, since both the liquid and the blood of the patient have the same concentration of salts and minerals.
Tubes for the external circulation of blood


One of them carries the blood from the vein through which it leaves the body, through the pump to the dialyzer. The other carries the blood from the dialyzer, again by the pump, to the vein through which the blood returns to the organism.
Devices for access to blood vessels

It is one of the most sensitive aspects of hemodialysis. Especially in patients who are undergoing treatment for years, blood vessels suffer considerably as a result of frequent punctures. For this reason, specially polished needles are used to cause minimal tearing, or external silicone tubes are implanted, called shunts, which carry blood from an artery to a vein outside the skin, and which serve to puncture them every time dialysis is performed.
Dialysis centers

The treatment is preferably carried out in so-called "dialysis clubs", units that have the necessary doctors and nurses, but who are not integrated into a hospital. This is done so that patients feel less sick, and also to avoid the high costs of hospital departments. In the Dialysis Clubs, an average of 50 patients is attended at the same time. Acute cases or especially serious cases are treated in the hospital. On the other hand there is also home hemodialysis, in which the patient is dialyzed at home, for which he has the necessary equipment and equipment and one or several relatives who have been trained to care for him.