Physicochemical principles of artificial kidney functioning. Methods for purifying colloidal systems: dialysis, electrodialysis, ultrafiltration

An artificial kidney is a device for removing toxic metabolic products from the patient’s blood that accumulate during severe kidney damage (acute and chronic). The operation of the device is based on the principle of removing low molecular weight substances from colloidal solutions due to diffusion and the difference in osmotic pressure on both sides of a semi-permeable cellophane membrane. Potassium, sodium ions, urea molecules, creatinine, ammonia, etc. freely penetrate through the pores of cellophane. At the same time, larger protein molecules, blood cells and bacteria cannot overcome the cellophane barrier. There are two main types of artificial artificial limb devices: devices with a cellophane tube with a diameter of 25-35 mm and devices with a plate cellophane membrane. The domestic artificial kidney refers to dialyzers with a plate-like cellophane membrane. Its diagram is shown in the figure. Blood from the patient flows through a catheter using a pump into the dialyzer, which is mounted on a tank containing 110 liters of dialysate solution. Passing between the cellophane plates of the dialyzer, the patient’s blood through the cellophane membrane comes into contact with the dialysate solution flowing towards it. After the dialyzer, the blood enters the performance meter and then returns through a filter and air trap via a catheter to the patient’s venous system. The flowing dialysate fluid is standard and contains all the main blood ions (K·, Na·, etc.), glucose in a concentration corresponding to the concentration of those in the blood of a healthy person. The solution is automatically heated to a temperature of 38° and saturated with carbogen to pH = 7.4. The clearance (purification coefficient) of the device for urea is 140 ml/min.

A plate made of organic glass is placed on the metal base of the dialyzer in a horizontal position. Two cellophane sheets are placed on it, which are covered with the next plate on top. In this way, 12 plates are laid, which are fastened with metal bolts. Cellophane membranes are perforated through special holes, as a result of which the intercellophane spaces are connected to each other. A pressure gauge is used to check the tightness of the apparatus assembly. Next, the dialyzer pump is assembled, to which is attached a blood supply catheter, and on the other side a tube attached to the inlet of the dialyzer. The outlet of the dialyzer is connected to a performance meter, to the upper end of which a blood return hose to the patient is attached. After this, the device is sterilized with diacid, washed with sterile saline and filled with blood or polyglucin. The connection of the device to the patient is carried out either by arteriovenous or venovenous method. In the first case, after exposure of the radial artery, blood is drawn into the apparatus using a vascular catheter inserted into its lumen. The return flow of blood from the device occurs through a catheter inserted into a superficial vein. In the second method, by exposing a large vein on the thigh, probing of the inferior vena cava is achieved, from the lumen of which blood is drawn. The blood flows back into the cubital vein. To quickly connect the device and carry out multiple dialysis, a shunt (vessel prosthesis) is placed between the catheterized radial artery and a nearby vein. After connecting the device, heparin is injected into the bloodstream to reduce and prevent blood clots. Hemodialysis is carried out for 4-12 hours, depending on the disease and condition of the patient.

An artificial kidney cannot completely replace kidney function, especially for a long time. However, for many months it is possible to maintain the vitality of the body at a sufficient level. In some cases, an artificial kidney is a preliminary stage of kidney surgery.

Artificial kidney. The operation of the artificial kidney apparatus is based on the principle of dialysis due to diffusion and the difference in osmotic pressure on both sides of a cellophane plate, which has the properties of a semi-permeable membrane. Small molecules of Mg··, K·, Na·, Ca·, Cl·, HCO 3 ions and simple organic compounds such as urea, creatinine, phenol derivatives freely penetrate through the pores of cellophane. At the same time, protein molecules, blood cells on the one hand, and possible bacteria on the other cannot overcome the cellophane barrier.

Among the many models of artificial kidney devices, two main types can be distinguished: devices with a cellophane membrane, shaped like a tube with a diameter of 25-35 mm, and devices with a plate-like cellophane membrane. The Kolff-Wachinger two-coil artificial kidney is most widely used abroad (Fig. 1). An important advantage of this artificial kidney model is that the reels with wound cellophane tubing leave the factory in a sterile state and can be used immediately if necessary. Ease of installation and handling, large dialysing surface (19,000 cm1) have made this model very popular. The disadvantages of the device are a large blood capacity and significant resistance to blood flow due to the tight winding of the two dialysis hoses.

Fig.1. Diagram of the Kolff-Wachinger kidney connected to the patient: 1 - blood filter; 2 - blood pump; 3 - dialyzer; 4 - dialysate solution; a - artery, v - vein.

Therefore, a pump is installed at the inlet of the dialyzer.

The Soviet model of an artificial kidney, designed at the Scientific Research Institute of Surgical Equipment and Instruments (NIIKHAI), is a type of dialyzer with a plate-like cellophane membrane.

Extensive clinical experience of Soviet and foreign clinicians shows the high effectiveness of hemodialysis in the treatment of patients with renal failure.

However, an artificial kidney does not replace other therapeutic measures. It is one of the most important parts of complex therapy. An artificial kidney cannot completely replace the multifaceted function of diseased kidneys, and for a long time.

In the USSR, artificial kidneys began to be used in 1958 in the urological clinic of the 2nd MMI on the basis of the 1st City Hospital. Currently, over 50 departments of clinical hospitals are equipped with artificial kidneys.

The connection of the device to the patient is usually carried out using two methods: arterial-venous or veno-venous. In the first case, after exposing the artery (usually the radial one), blood is drawn into the apparatus using a vascular catheter inserted into its lumen. The return flow of blood from the device to the patient occurs through a probe inserted into a superficial vein (usually the ulnar vein). With the veno-venous connection method, puncture or exposure of a large vein on the thigh is achieved by probing and drawing blood from the inferior vena cava. The return flow of blood occurs through a vein in the forearm.

Currently, the puncture method of vascular catheterization has become widespread. A puncture of the femoral artery and vein is performed under the pupart's ligament and the corresponding catheters are inserted into the vessels through a guidewire, which are connected to the device using commutating lines. If during the treatment of a patient multiple use of hemodialysis is expected, then a permanent arteriovenous shunt is installed on the forearm according to Scribner (V.N. Scribner). The essence of the method is to probe the radial artery and the adjacent vein on the forearm. These probes are connected with special devices, and blood flows from the artery directly into the vein. For hemodialysis, changing the connector allows you to connect the patient’s circulatory system with the artificial kidney apparatus in a few minutes. After hemodialysis, the shunt is restored again using a semicircular connector.

Artificial hemophilia is carried out by periodic administration of heparin (2 mg/kg). After hemodialysis, the effect of heparin in the patient’s blood is neutralized by introducing a solution of protamine sulfate. All parts of the device that come into contact with the patient’s blood must be siliconized and sterilized.

A diagram of the Soviet artificial kidney model is shown in Fig. 2. Blood from the patient flows through the catheter (1) using a pump (2) into the dialyzer (3). Passing between the cellophane plates of the latter (through each of its 11 sections), the patient’s blood through the cellophane plate comes into contact with the dialysate solution flowing towards it. Its composition is usually standard and contains all the main blood ions (K·, Na·, Ca··, Mg·, Cl·, HCO 3) and glucose in concentrations necessary to correct the electrolyte composition of the patient’s blood. After the dialyzer, the blood enters the performance meter (4), where blood clots and air are collected. The blood is then returned through the catheter to the patient’s venous system. Using an automatic heater (8), the dialysate solution is brought to a temperature of 38° and saturated with carbogen so that its pH is 7.4. Using the pump (9), the dialysate solution is supplied to the dialyzer. The blood flow rate in the dialyzer is usually 250-300 ml/min. The clearance of the device is urea 140 ml/min.

Rice. 2. Diagram of the Soviet model of the “artificial kidney” apparatus: 1 - catheter; 2 - blood pump; 3 - dialyzer; 4 - performance meter; 5 - air trap; 6 - filter; 7 - catheter for returning blood to the patient; 8 - heater; 9 - pump for dialysate fluid; 10 - tank for dialysate solution; 11 - oxygen rotameter; 12 - rotameter for carbon dioxide; 13 - hydraulic drive of the perfusion pump.

Currently, a new artificial kidney model has been constructed (Fig. 3). The basic principle of its operation remains the same. The device has two independent sections with a dialysing surface area of 8000 cm 2 each, with two independent pumps; it is equipped with a special device for regional heparinization and is more convenient for the treatment of patients with chronic renal failure due to the possibility of reducing the dialysing surface area.

Rice. 3. General view of the new model of the Soviet “artificial kidney” device designed by NIIKHAI.

The most effective and convenient for clinical use are those models of artificial kidney that satisfy the following basic requirements: high intensity of blood dialysis, ease and safety of handling the device and a small volume of blood. These are devices from NIIHAI (USSR), Kolff-Wachinger (USA) and Dogliotti (Italy). They are especially good in the treatment of patients with acute renal failure. The most convenient devices are considered to be the modernized Kolff model and the two-plate artificial kidney of the Kiel system. Kaden (W. Kaden, German Democratic Republic) proposed an original model of an artificial kidney apparatus for the treatment of chronic renal failure. Its important advantages are portability and low cost.

The use of chronic hemodialysis in modern conditions is an important task. According to the III International Congress of Nephrologists, in some countries (USA), per 100 million population, up to 50 thousand patients with chronic renal failure of various etiologies annually need chronic hemodialysis. By using an artificial kidney in a patient with chronic renal failure twice a week, it is possible to maintain subnormal levels of azotemia, normal water-electrolyte balance and a satisfactory general condition of the patient. Thus, the life of patients with end-stage chronic renal failure can be extended for many months and even years. Artificial kidneys are beginning to be used at home, although so far in rare cases. Repeated hemodialysis in patients with chronic renal failure is associated with a number of significant difficulties and various complications. These primarily include thrombosis of arteriovenous shunts. The use of Teflon-silastic material made it possible to extend the service life of the shunt to 6-9 months. Some patients suffer from often severe peripheral nephropathy. Calcium metabolism is disrupted, which is manifested by metastatic calcification and osteoporosis. Anemia requires constant blood transfusions. Frequent complications are intermittent infection and hypertension. Testicular atrophy (in men) and amenorrhea (in women) are quite common phenomena. Finally, during repeated hemodialysis, hypercalcemia, severe anemia, septicemia, and pyrogenic reactions may develop.

It is more advisable to use chronic hemodialysis in patients in truly terminal stages of chronic renal failure, taking into account possible homo- and heterotransplantation of the kidney during treatment.

In patients with acute renal failure, hemodialysis allows one to achieve a significant clinical effect in a few hours by ridding the body of nitrogenous waste, normalizing water and electrolyte balance, and eliminating acidosis. This sometimes temporary effect allows the body to enhance regenerative processes in the kidneys and liver, helping to restore their function. Therefore, in most etiological forms of acute renal failure, the use of an artificial kidney is indicated. These include conditions in which kidney function is often deeply impaired: collapse of the peripheral circulation due to severe operations, trauma, bleeding, post-abortion infection, incompatible blood transfusion, poisoning with nephrotoxic poisons, acute anuric glomerulonephritis, occlusion of the urinary tract. In case of chronic renal failure in the acute stage, repeated hemodialysis can significantly improve kidney function.

When determining indications for hemodialysis, it is important to take into account the state of the nervous system, respiratory organs, cardiovascular system and functional state of the liver.

The use of an artificial kidney in patients in a state of uremic coma should be considered as a late intervention, and, naturally, the success of treatment is not always positive.

Among biochemical disorders, the leading indication for hemodialysis is
hyperazotemia, when residual serum nitrogen is 150-200 mg% (urea content 350-400 mg%), creatinine content 12-15 mg%. An increase in potassium content in the blood serum to 7 mEq/L or higher, a decrease in the alkaline reserve to 10 mEq/L, together with other water and electrolyte disturbances, are indications for emergency hemodialysis.

Among patients with acute renal failure, in 35-45% the disease is not too severe. Despite the presence of anuria, azotemia and other disorders, treatment of these patients can be carried out without the use of hemodialysis.

Contraindications include decompensation of the cardiovascular system, liver failure, and active septic process in the body in the phase of intermittent bacteremic shock. A fresh focus of bleeding is not considered an absolute contraindication to hemodialysis. The use of regional heparinization using special equipment (only in an artificial kidney apparatus) allows one to avoid increased bleeding.

The use of an artificial kidney according to strict indications, taking all precautions and carefully monitoring the patient during and after dialysis is practically safe and does not threaten any complications.

The invention of the artificial kidney device saved the lives of hundreds of thousands of people who were diagnosed with acute or chronic kidney failure. The hemodialysis device removes toxic compounds and uric acid salts from the bloodstream, normalizes water-salt metabolism, and prevents the occurrence of arterial hypertension. Without changing blood volume, the “artificial kidney” cleanses the human body of toxic substances during alcohol intoxication and drug overdose.

What is an “artificial kidney”

Acute renal failure, extensive intoxication, pulmonary edema lead to a decrease in the functional activity of the kidneys - they cannot cope with filtering the blood and removing metabolic products from the body. The concentration of toxic substances rapidly increases, provoking the death of brain cells due to insufficient supply of molecular oxygen.

To save a person from imminent death, hemodialysis is performed - the blood is purified through a special membrane that imitates the basal renal membrane.

With the help of an “artificial kidney” the following are removed from the blood:

Products of protein metabolism are urea and its compounds.
Creatinine, the end product of chemical reactions in muscle tissue.
Poisonous compounds of mercury, chlorine, arsenic, biological toxins of higher fungi and plants.
Pharmacological and narcotic drugs: barbiturates, opioids, phenobarbital, neuroleptics, tranquilizers.
Methyl and (or) ethyl alcohol.
Excess liquid.

Depending on the stage and degree of development of the disease, the patient undergoes the procedure several times a week. This blood purification takes about 5-6 hours, while the urea concentration is reduced by more than 70%.

The “artificial kidney” is designed as follows:

Synthetic or cellulose membrane.
Blood purification system.
Dialysate preparation system.

Increasingly, cellophane membranes are used during the procedure. They make it possible not to filter out low-molecular useful substances - microelements and minerals. And pathogenic bacteria and toxic compounds are removed.

Hemodialysis is used in the treatment of acute alcohol intoxication

Hemodialysis

Blood purification using an “artificial kidney” requires preparing the patient for the procedure. Their blood vessels are not always in good condition, and many hours of removing and injecting fluid can ruin them completely.

The problem can be solved in the following ways:

A fistula is formed from an artery and a vein, usually on the forearm. After surgery, the vascular walls thicken and become denser, so even frequent hemodialysis cannot compromise their integrity.
Under local anesthesia, a catheter is sewn into a vein located in the groin area. The advantage of this method is the ability to use the device immediately after the operation.

For a patient with an implanted catheter or a formed fistula, physical activity and heavy lifting are contraindicated.

Before the hemodialysis procedure, medical personnel measure the patient's pulse rate and blood pressure. The most modern blood purification devices are equipped with devices for preliminary taking of these readings. A person should also weigh himself to assess possible tissue swelling and calculate the amount of fluid that should be removed from the body.

Toxic substances and waste products are removed from the bloodstream by creating excess hydrostatic pressure on the fluid separated from the solvent by a membrane. In this case, no solvent diffusion occurs, since the pressure equalizes the content of dissolved substances on both sides of the semi-permeable membrane.

The “artificial kidney” is equipped with a special compact pump, with the help of which blood flows into a dialyzer with a membrane. After a few hours, the patient’s blood is completely cleansed, and the injection site is treated with disinfectant solutions, followed by the use of a sterile dressing.

To purify the blood using the “artificial kidney” method, a fistula is created

Principles of operation of the “artificial kidney”

All substances passing through a semi-permeable membrane during dialysis form dialysate. Osmotic pressure is created by the counter flow of purified blood and dialysate solution. The composition of the latter is selected according to the individual indicators of the patient’s health status; sometimes this function is performed by the device itself.

The operating principle of the device is as follows:

Acute and chronic renal failure increases the concentration in the blood of toxic nitrogenous compounds and products of protein metabolism. Osmotic pressure promotes their penetration through the membrane pores into the less saturated dialysate solution.
The dialysate solution contains magnesium, sodium, potassium cations and chlorine anions. Their concentration corresponds to what a healthy person should have. The passage of fluids through the membrane allows you to replenish the amount of electrolytes in the patient's blood. Used for kidney ventilation.
With a decrease in the functional activity of the kidneys, the acidity of biological fluids increases. The dialysate solution contains sodium bicarbonate, which binds to blood cells. Blood pH shifts to the alkaline side and normalizes.
Disruption of filtration processes in the structural elements of the kidneys provokes tissue swelling. As blood passes through the semipermeable membrane, excess fluid is removed from it and accumulates in the dialysate solution. This process makes it possible to stabilize the condition of patients with cerebral edema.
Thrombophlebitis and venous insufficiency are dangerous due to possible blockage of the lumen of blood vessels by a large thrombus. Hemodialysis using anticoagulants prevents the aggregation of conglomerates.

To prevent blockage of blood vessels by air bubbles (embolism), the “artificial kidney” device is equipped with a device that destroys them or prevents their formation. After hemodialysis, measurements of the content of urea and its compounds in biological fluids are carried out.

Carrying out hemodialysis on an outpatient basis

Main types of artificial kidney devices

Patients with kidney disease tend to lead a normal lifestyle, go to work, and spend time with family. Manufacturers of the “artificial kidney” have provided the ability to purify blood at home. A person can independently carry out the procedure at a time convenient for him and the required number of times. Unfortunately, such a device is expensive and the patient must undergo special training courses before purchasing it.

Hemodialysis is also performed:

At the outpatient clinic. The procedure is carried out in order of priority under the supervision of medical personnel. Patients are delivered by ambulance.
In a hospital or intensive care unit. Blood purification is carried out in seriously ill patients with acute renal failure. Patients with poisoning by toxic substances, alcohol intoxication, and drug overdose are also admitted here.

With the development of the chemical industry and the expansion of the production of pharmacological drugs, the number of intoxications is increasing. Developers of blood purification devices are constantly improving artificial kidney devices, adding convenient devices. You can trace the evolution of medical equipment:

Conventional hemodialysis. Relatively small flow of blood and dialysate. The area of the cellulose membrane is about 1 square. meters.
Highly effective hemodialysis. The procedure does not take more than four hours. The total surface area of the semi-permeable membrane is 2 square meters. meters, the speed of movement of liquids reaches 250 ml/min.
High flow hemodialysis. Membranes have been improved: very large conglomerates can pass through them. The procedure allows you to preserve beneficial substances and microelements in the blood and prevents the occurrence of complications.

Hemodialysis machines differ in the design of the filter for blood purification:

Disc dialyzers. Parallel plates with a semi-impermeable membrane allow constant control over the quality of filtration. Reduced risk of thrombosis, low volume of purified blood.
Capillary dialyzers. When carrying out the blood purification procedure, the risk of complications is minimized due to the rapid flow of fluids.

The choice of device is made by medical personnel based on the patient’s condition and the capabilities of the medical institution.

Use of an “artificial kidney” in a hospital

Portable "artificial kidney"

Ten years ago, American scientists developed a portable “artificial kidney”. The portable device weighs no more than 3.8 kg and is powered by regular batteries. To carry out blood purification, the formation of a fistula or the installation of a built-in intravenous catheter is also carried out.

The portable artificial kidney device does not require much time for installation - within a few minutes the doctor connects the medical equipment. If necessary, the device can operate around the clock. This is not only due to improved design, but also due to the relatively slow flow of fluid.

Implantable "artificial kidney"

An implanted “artificial kidney” will soon become a common reality. Several years ago, the development of American scientists was presented to the public. The hemodialysis device is designed for patients with chronic renal failure. The development is especially relevant when there is a current shortage of donor organs or when they are rejected by the human body’s own cells.

At this stage, the implanted “artificial kidney” is tested in the laboratory. The essence of the technique is that a compact device performs the filtration function of the kidneys. The device is equipped with biological filters containing renal tubular cells, and the energy required for operation is produced by the flow of blood.

Donor kidney transplant

A kidney transplant is a surgical procedure that involves transplanting an organ obtained from another person. Renal replacement therapy is used to treat patients with chronic renal failure of various etiologies. Usually the need for a donor kidney arises at the last stage of the course:

Diabetic nephropathy.
Chronic pyelonephritis.
Polycystic kidney disease.
Chronic glomerulonephritis.

The operation significantly prolongs the patient’s life and improves its quality. Kidney transplantation is vital for young children with congenital renal pathologies, since constant hemodialysis leads to developmental delays in the child.

Contraindications to hemodialysis

The method of blood purification using an “artificial kidney” is contraindicated in the following cases:

Severe arterial hypertension.
Acute viral and bacterial infections.
Open form of tuberculosis.
Heart attack and stroke.
Blood clotting disorder.

These contraindications are not taken into account if the patient’s life is threatened, and a connection to the “kidney” is made. After all, hemodialysis was created to prolong the patient’s life, so all risks are taken into account and attempts are made to eliminate them.

Patients suffering from the disease develop insufficiency of their functions as the disease progresses. If kidney filtration of blood decreases to 10–15%, then such patients undergo hemodialysis, that is, forced cleansing and removal of harmful substances from the body. This function is performed by an artificial kidney device, the use of which is indicated for patients with renal failure.

If the kidneys fail to cope with their function, then the patient experiences fatigue, vascular hypertension, edema, and dyspeptic disorders. A dialysis device helps maintain the fluid ratio in the body and thereby normalize the acid-base balance.

What is an “artificial kidney”

The artificial kidney device is designed to cleanse the blood of toxic elements that accumulate in the blood due to insufficient excretory function of the organ.

The use of the device helps to normalize electrolyte and acid-base balance, remove toxins from the body in case of poisoning, as well as excess water in case of swelling.

The provided operating algorithm of the device is based on biological processes occurring in the body. During the procedure, the volume of circulating blood remains normal, that is, it does not increase or decrease.

How the device works

A hemodialysis machine is a device weighing up to 80 kg that works like a pump. The patient's blood passes through the dialyzer, where the purification process is carried out. This equipment is made up of a large number of tubes through which blood moves. They are washed externally with dialysate solution. The system works on the following principle: through the membrane from which the tubes are made, toxins and excess microelements penetrate into the liquid, while large molecules of protein, bacteria, and blood components remain. The process follows the laws of diffusion and osmotic pressure difference.

In acute renal failure, the use of hemodialysis daily is indicated until the functions of the organ are restored or the symptoms of poisoning of the body are relieved. If the form of the disease is chronic, then the procedure is carried out 2-3 times a week.

The procedure is performed by a nephrologist in a hospital setting or in specialized hemodialysis centers.

Types of devices

There are two main types of devices. The first type is a cellophane membrane in the form of tubes, and the second is made of plates. The plate form requires less heparin for the procedure, as well as a small amount of blood, which reduces the risk of complications for the patient. The tubular shape of the membrane allows you to purify the blood faster and better, since it has a larger area. The device consists of three blocks.

pumps that supply heparin and pump blood;
instruments indicating pressure;
device to prevent the appearance of air bubbles.

systems for air elimination, temperature control;
mixing devices, monitoring filtration;
sensor for blood leakage into the dialyzer.

Module 3 is a filter and hemodialysis membrane.

The design of the device allows you to automatically monitor the patient’s pressure, his hemoglobin level, and also adjust the composition of the dialysate solution. Modern machines independently prepare the dialysate solution according to the patient’s parameters. These characteristics apply only to devices used in hospitals, the best of which are considered to be devices from the BAXTER-1550, NIPRO SURDIAL, and Dialog Advanced concerns.

There are devices that can be used in an outpatient setting. This is a portable artificial kidney device, which is intended for home use. Its technical capabilities are lower than those of stationary devices, but it performs the main function (blood purification). Such devices are worn on a belt and weigh up to 7 kg, and are performed at any time of the day when the patient needs it. The duration of the manipulation is 3–4 hours.

The use of the device has the following features:

safety (the risk of infection is eliminated);
ease of use;
performing manipulations at any time of the day.

These are the positive aspects of the device. The negative ones include the following:

high price of the device;
control of health workers during the first sessions;
need to undergo training.

Despite some disadvantages in the operation of the device, its use brings patients a certain freedom of movement, since blood purification can be carried out at any time, without waiting in line at the hospital. The portable artificial kidney allows patients to perform light physical work and also provides dialysis at night.

Who should not use the device

The procedure has its contraindications. It should not be done on patients with the following pathologies:

mental illness;
oncological pathologies;
leukemia or anemia;
pathology of the central nervous system;
old age (over 80 years);
diabetes mellitus (age after 70 years);
having more than two serious diseases.

The procedure cannot be performed on patients suffering from alcoholism or drug addiction, who have an active form of tuberculosis, or who are predisposed to the development of massive bleeding.

Undesirable effects

After or during the procedure, patients may develop undesirable effects:

The appearance of complications becomes the body’s reaction to the behavior of the manipulation. If the patient does not adhere to dietary nutrition, such side effects become more frequent. Patients with renal failure are prescribed a diet that strictly prohibits alcohol, hot, spicy and smoked foods, and limits the consumption of salt and liquid. If the rules of nutrition are violated, the patient creates additional stress on the kidneys, since an increased amount of salt retains moisture in the body, leads to the formation of edema, increases the load on the heart muscle, and contributes to arterial hypertension.

During dialysis, calcium ions are washed out of the body, which contributes to destructive disorders in bone tissue. Deficiency of erythropoietin (it is produced by healthy kidneys) leads to changes in blood composition. Pericarditis occurs due to increased workload on the heart, since during the procedure it needs to pump a large volume of blood.

Conclusion

Kidney failure, which requires constant treatment, is a very serious disease. There are no accurate statistics to determine how long a patient undergoing forced blood purification will live. But still, carrying out the procedure along with compliance, as well as normalization of the motor mode, will prolong the patient’s life. But how much depends on the individual characteristics of the body and concomitant diseases.

In a healthy person, the kidneys work normally, filtering waste and liquids even in large volumes. In some cases, the body cannot cope with its work and the concentration of toxins becomes extremely high. This condition is called renal failure.

This problem lies in the complete or partial loss of the ability of internal organs to process and excrete urine. If this problem is not treated, the person may die from intoxication, so special procedures are carried out. In subsequent paragraphs of the article, the topic of hemodialysis will be covered in more detail - what it is and why do it.

Principle of operation

The concept of program hemodialysis refers to a special procedure that involves removing toxins from the blood.

For this, the efferent method and a special apparatus are used, which is called "artificial kidney".

With hemodialysis it is possible to:

extract toxins that are formed during metabolism;
restore the balance of water and electrolytes.

The procedure is mainly carried out in stationary conditions and involves the use of a device with a set of special membranes that have selective permeability. The body is cleansed by removing toxins and high molecular weight substances from the blood that can pass through the membrane.

Depending on its type and the type of dialysis solution, the blood can be cleansed of certain toxins and even certain proteins. In addition, some solutions can be used to replenish mineral deficiencies in the human body.

The “artificial kidney” consists of several elements:

perfusion device;
dialyzer;
apparatus for mixing and supplying dialysis solution;
monitor.

The machine works using a special perfusion device that helps blood flow to the dialyzer. Its operating principle is similar to a pump. After cleansing, the device directs the blood back into the human body.

The dialyzer is the basis of the machine. It is in it that there is a special membrane that allows blood filtration.

It is a reservoir divided into two parts by a special membrane. Blood is supplied to it, and on the other side - dialysis solution. Interacting through a membrane with a certain degree of permeability, the blood is purified and reintroduced into the body.

An apparatus for mixing and supplying the solution is necessary so that the blood is purified and pure dialysate is supplied to the membrane, and the dialysate with waste enters a separate reservoir.

The monitor on the device is designed to track the speed of blood flow. Normally, this indicator should be about 300-450 ml/min. If the blood flow is slow, then the duration of the procedure increases, and if it is higher, then the blood does not have time to be completely cleansed.

In order to normalize the speed of blood flow or, if frequent dialysis is necessary, a special fistula(see photo).

It facilitates the connection of the device and connects the vein and artery. To install it, a special operation is required. Within six months, the fistula matures and reaches the required stage for dialysis.

In general, the entire procedure takes about 5-6 hours. During the session, the patient can engage in any quiet activities.

The procedure must be carried out by specially trained personnel.

Types of hemodialysis

Hemodialysis is divided into several types depending on whether the procedure is carried out in a hospital or at home, as well as on the functionality of the device.

Also distinguished:

hemodialysis;
peritoneal dialysis.

In the first case, an artificial membrane is used to filter the blood, and in the second, the peritoneum is used.

By venue procedures include hemodialysis:

at home;
outpatient;
during inpatient treatment.

Hemodialysis at home involves the purchase of a special device by a person.

Outpatient procedure is carried out in the hospital on a first-come, first-served basis three times a week, but the equipment for them is more specialized. The duration of the procedure is 4 hours.

In this case, the person is under the control of the attending physician, who can change the fluid circulation speed settings, control the volume of blood and dialysate, and also monitor the pressure and level of hemoglobin in the blood. However, many patients do not like the need to wait and regularly visit the clinic.

Inpatient hemodialysis involves the patient staying in the hospital. There are not many differences from the outpatient procedure. The advantages also include constant monitoring by a doctor, while the disadvantages are the need to stay in a hospital in an inpatient department. In addition, if doctors are not careful enough, a person can become infected with hepatitis B.

Functionality of the devices for hemodialysis are also different, so there are three types of procedures:

regular;
highly efficient;
highly accurate.

Each method has its own characteristics depending on the type of membrane in the device. Conventional hemodialysis involves using a device with a membrane area of up to 12.5 sq.m. This material allows you to filter out small molecules at low speed (200-300 ml/min). In this case, the entire procedure takes about 5 o'clock.

Highly effective hemodialysis is carried out using a membrane with an area of 2.2 sq.m. At the same time, the speed of blood passage increases to 350-500 ml/min. At the same time, the dialysis current is also approximately twice as high. This cleanses the blood 1-2 hours faster, and it itself is better filtered and becomes cleaner than with conventional dialysis.

High-precision hemodialysis is applied using a high-sensitivity membrane. It allows the passage of not only small, but also large molecules, thereby allowing the blood to be purified from a greater number of toxic substances.

A feature of this type of procedure is the possibility of penetration of more substances from dialysis through the membrane, so it is necessary to monitor its quality.

At what creatinine level is it prescribed?

The main problem for which hemodialysis is prescribed is renal failure, since the procedure is necessary for such a patient and makes it possible to prolong his life. However, it is not always prescribed, but only at a certain concentration of creatinine in the blood. With indicators over 800-1000 µcol/l hemodialysis is already prescribed.

Indications also include:

alcohol intoxication;
disturbances in the electrolyte composition of the blood;
drug overdose;
poisoning with certain poisons;
overhydration.

With all its advantages, the procedure also has contraindications. Some of them are absolute, that is, use hemodialysis strictly prohibited. This:

cirrhosis of the liver;
cerebral vascular lesions;
leukemia;
anemia;
CNS lesions;
age from 80 years (70 if diabetes mellitus is present);
malignant tumors;
lung diseases;
chronic form of hepatitis;
pathologies of peripheral vessels in the stage of decompensation;
epilepsy;
schizophrenia;
psychoses;
alcoholism;
coronary heart disease against the background of a previous myocardial infarction;
heart failure;
addiction.

In other cases, the decision to carry out a blood purification procedure can only be made by the attending physician:

diseases with a high risk of developing massive bleeding after administration of an anticoagulant;
active forms of tuberculosis.

How many years do people live on hemodialysis - statistics

Considering that most often regular hemodialysis is prescribed mainly for renal failure or kidney problems, the overall life expectancy of a person has already been reduced.

If you do not replace the affected organ with a donor one, but use an “artificial kidney” directly, then life expectancy can be even about 20 years, depending on the characteristics of a person’s health and general condition. The maximum age is 40 years.

A person who requires regular hemodialysis due to weakened heart muscle is predicted to live for about 4 years.

The average life expectancy is about 6-12 years. In this case, the patient dies not from kidney disease, but from infectious or inflammatory diseases and their consequences.

This happens as a result of the fact that the kidneys cannot fully perform their tasks and the person’s immunity is greatly weakened. As a result, any infection or virus can cause irreparable harm to health, even with treatment.

Not every person is suitable for artificial blood purification, so a fairly high percentage of deaths occur in the first year. If the human body functions normally for a year, then in 76% of cases he will live for at least another 5 years if all the doctor’s requirements are met.

Complications of hemodialysis

Since the kidneys are an important system for cleansing the body, disturbances in their functioning cause problems with the functioning of other internal organs. Complications may include:

arterial hypertension;
anemia;
CNS lesions;
bone diseases;
hyperkalemia.

Arterial hypertension is an increase in blood pressure. If such a problem occurs, the doctor prescribes a special diet. If the problem is not addressed promptly or neglected, it may contribute to the development of a heart attack or stroke.

Anemia is a decrease in the concentration of red blood cells in the blood. This reduces the saturation of the body's cells with oxygen. Anemia is caused by a lack of erythropoietin, which is produced by healthy kidneys. The development of this condition is also caused by large blood losses or lack of iron and vitamins in the diet.

Disturbances in the functioning of the nervous system suggest a decrease in the sensitivity of the limbs. This condition can be caused by diabetes, B12 deficiency, or an excess of toxins in the blood.

Bone diseases occur when kidney problems are advanced, when the body cannot obtain vitamins and minerals from the blood. The patient has brittle bones and severe bone destruction because the kidneys cannot allow calcium to be absorbed more easily by converting vitamin D.

In addition, there is deposition of excess calcium and phosphorus. As a result, it happens formation of ulcers and inflammations.

Pericarditis is inflammation of the pericardium, or lining of the heart. This happens when fluid accumulates around the organ, which causes a decrease in blood output and heart contractions.

An increase in the concentration of calcium in the blood or hyperkalemia occurs when diet is abandoned during hemodialysis. Its peculiarity lies precisely in reducing the consumption of this mineral with food. If the concentration of potassium in the blood increases, it may become cause of cardiac arrest.

To prevent the development of complications, it is necessary:

strictly follow a diet;
maintain personal hygiene;
drink a strictly limited amount of liquid;
take prescribed medications promptly and regularly;
Tell your doctor if you have symptoms of complications;
undergoes regular examinations;
take prescribed tests in a timely manner.

If all preventive measures are followed, the risk of complications is minimized.

At home - is it possible and how?

Hemodialysis can be performed at home. A special device is required, which is intended specifically for home use. Some of them are quite large, but modern models are small and weigh from 4 to 7 kg and can be attached to the body.

The advantages of the procedure at home are relative safety, since only one person uses the device. In addition, dialysis can be performed at any time and there is no need to correlate the schedule with the working hours of the clinic and doctor.

The disadvantages of home hemodialysis are the need to train a loved one to operate the machine. At first, the procedure must be carried out under the supervision of a visiting medical professional. In addition, the cost of the device for home use is high and amounts to about 15-20 thousand dollars.

Kidney transplant

Hemodialysis is prescribed to people suffering from kidney failure. Procedure cannot completely replace an organ, so the person’s condition gradually worsens. In addition, the disease requires regular examinations by a doctor and visits to the hospital for the procedure.

Modern medicine allows some patients to improve their quality of life with the help of a donor kidney transplant. The method is quite complex and there is a high risk of organ rejection. In addition, the wait for a donor organ can last for years, and after a transplant, a person will take drugs that suppress the immune system for the rest of his life.

Peritoneal dialysis

Peritoneal dialysis is also artificial blood purification method. But to carry it out, it is not artificial material (membrane) that is used, but a part of the human body or its peritoneum. It is a thin membrane that covers the internal organs of the abdominal cavity.

The advantages of this dialysis method are that the peritoneum, unlike the membrane, has a more selective permeability and allows substances with a higher molecular weight to pass through it. Thus, more types of toxins pass through it.

The procedure is carried out quite slowly. The dialysate itself is placed in the patient's abdominal cavity and blood is filtered through it through the vessels in the peritoneal walls.

The advantage of the method is its ability to be used by patients with end-stage renal failure, as well as if there is no possibility of installing a fistula.

For the procedure, an improved apparatus and peritoneal catheters are used, which provide high-quality drainage of the abdominal cavity. The catheter is fixed with a Dacron cuff in the subcutaneous fat. The catheter is surgically inserted.

This procedure may have some complications. The main ones include peritonitis or inflammation of the peritoneum. Other features are approximately the same as with standard hemodialysis.

The procedure is usually performed while the patient is in the hospital, since requires constant medical supervision to change the dialysate and monitor the patient's health.

Nutrition and diet

Hemodialysis requires strict adherence to certain dietary habits. They consist in reducing the intake of products into the patient’s body, which can increase the rate of endotoxin production.

The main principle of the diet is to limit the patient’s fluid intake. His kidneys can produce from 500 to 800 ml of diuresis per day. But at the same time, the overall increase in body weight should not exceed 2.5 kg. If there is an increase in fluid loss through sweat, the volume of fluid consumed may be slightly higher.

An important feature of nutrition in chronic renal failure and acute renal failure is complete abstinence from salt or its minimal use. You are allowed to eat no more than 8 g per day.

Find out the principles of treatment for acute renal failure in our article.

In addition to limiting the consumption of salt and salty foods, it is necessary to limit the consumption of foods rich in potassium. Their list is as follows:

bananas;
citruses;
dried fruits;
potatoes and some vegetables;
natural juices;
bran;
greenery;
cereals;
chocolate;
cocoa;
nuts.

If a person counts the potassium consumed, then its volume per day is should not exceed 2000 mg.

As with potassium, you should limit your intake of foods with phosphorus (fish, cheeses, etc.).

With the above restrictions, a person should eat a sufficiently varied diet and get enough protein and energy.

When adhering to a diet, it is also necessary to take into account the individual characteristics of the body, as well as follow the recommendations of the attending physician.

In case of any problems, you must contact him immediately to avoid worsening the condition.

How the hemodialysis process is carried out, see in detail in the video:

opochke.com

What is an “artificial kidney”

The artificial kidney device is designed to cleanse the blood of toxic elements that accumulate in the blood due to insufficient excretory function of the organ.

The use of the device helps to normalize electrolyte and acid-base balance, remove toxins from the body in case of poisoning, as well as excess water in case of swelling.

How the device works

The procedure is performed by a nephrologist in a hospital setting or in specialized hemodialysis centers.

Types of devices

pumps that supply heparin and pump blood;
instruments indicating pressure;
device to prevent the appearance of air bubbles.

systems for air elimination, temperature control;
mixing devices, monitoring filtration;
sensor for blood leakage into the dialyzer.

Module 3 is a filter and hemodialysis membrane.

There are devices that can be used in an outpatient setting. This is a portable artificial kidney device, which is intended for home use. Its technical capabilities are lower than those of stationary devices, but it performs the main function (blood purification). Such devices are worn on a belt and weigh up to 7 kg; they perform dialysis at any time of the day when the patient needs it. The duration of the manipulation is 3–4 hours.

The use of the device has the following features:

safety (the risk of infection is eliminated);
ease of use;
performing manipulations at any time of the day.

These are the positive aspects of the device. The negative ones include the following:

high price of the device;
control of health workers during the first sessions;
need to undergo training.

Who should not use the device

The procedure has its contraindications. It should not be done on patients with the following pathologies:

mental illness;
oncological pathologies;
leukemia or anemia;
pathology of the central nervous system;
old age (over 80 years);
diabetes mellitus (age after 70 years);
having more than two serious diseases.

The procedure cannot be performed on patients suffering from alcoholism or drug addiction, who have an active form of tuberculosis, or who are predisposed to the development of massive bleeding.

Undesirable effects

After or during the procedure, patients may develop undesirable effects:

The appearance of complications becomes the body’s reaction to the behavior of the manipulation. If the patient does not adhere to dietary nutrition, such side effects become more frequent. Patients with renal failure are prescribed a diet that strictly prohibits alcohol, spicy, spicy and smoked foods, and limits salt and liquid intake. If the rules of nutrition are violated, the patient creates additional stress on the kidneys, since an increased amount of salt retains moisture in the body, leads to the formation of edema, increases the load on the heart muscle, and contributes to arterial hypertension.

Conclusion

Kidney failure, requiring constant hemodialysis, is a very serious disease. There are no accurate statistics to determine how long a patient undergoing forced blood purification will live. But still, carrying out the procedure along with observing the rules of dietary nutrition, as well as normalizing the motor mode, will prolong the patient’s life. But how much depends on the individual characteristics of the body and concomitant diseases.

nephrologinfo.ru

Indications and contraindications

The procedure performed by this device is called hemodialysis and is used in the following cases:

If the patient is diagnosed with acute or chronic renal failure.
In case of poisoning with drugs or alcohol.
For diseases that contribute to the accumulation of fluid in the body (pulmonary edema, cerebral edema, heart failure)

This procedure is prescribed in cases where conservative treatment methods do not produce positive results.

Despite the fact that hemodialysis is a fairly simple procedure, it still has a number of contraindications such as:

The presence of any chronic diseases.
Diseases of the nervous system.
Epilepsy.
Tuberculosis of any form.
Hepatitis.
Cirrhosis of the liver.
Oncological diseases.
Heart attacks, strokes.
Age over 70 years.

How it is carried out, the device

Dialysis can be carried out both at home and in special medical centers and takes from 4-5 hours; the frequency of procedures depends on the type and complexity of the disease. Before starting, the patient undergoes a medical examination, undergoes tests, has his blood pressure and pulse measured, and is also weighed.

The device is designed to cleanse venous blood of toxins and waste; it is connected to the patient’s veins and, with the help of a pump, the blood moves to a special membrane, and on the other side a solution - a dialyzer - comes in to cleanse it. The structure of the membrane and the composition of the dialyzer fluid directly depend on the patient’s disease and take into account the individual characteristics of his body.

People who are prescribed dialysis not as a one-time procedure, but as a method of treatment, must adhere to a special diet that limits:

Drinking fluids.
Products that contain large amounts of potassium and phosphorus.
Strict restriction of salt intake.

Inpatient or outpatient use of the device occurs under the guidance of medical personnel in equipped premises.

To create a comfortable environment for patients, scientists have invented a portable device for dialysis. True, the price of this device is very high. And before using it, the patient must undergo training.

Patients suffering from chronic renal failure often require an organ transplant, but due to the shortage of donor organs and cases of the patient's body rejecting foreign organs, a kidney replacement implant was invented.

Possible complications

Due to the fact that devices are most often used to remove fluid from the body, various side effects occur:

Blood pressure decreases or increases.
Fatigue appears.
Drowsiness.
Nausea and vomiting occur due to decreased blood pressure.
Headaches associated with pressure changes.
Cramps in the limbs.
An increase in temperature caused by infection in the body.

The extent to which such symptoms will manifest directly depends on the amount of fluid removed from the body.

Despite possible complications, this procedure saved many lives.

pochkizdorov.ru

general information

American inventor John Abel created the device in 1913, which is the prototype of the modern artificial kidney. The device was first used in 1944 by medical scientist William Colf. The hemodialysis machine is quite large in size. Now, in order to undergo the blood purification procedure, a person must stay in the hospital for several hours at least 2 times a week. This procedure cleanses the blood of waste by an average of 60%.

Acute or chronic kidney failure can be fatal. The condition is extremely dangerous and requires immediate surgical intervention; the creation of a device - an “artificial kidney” - has become the only salvation for patients with a similar diagnosis. Without changing the volume of blood in the body, the hemodialysis device ensures the removal of toxic compounds, while normalizing water-salt metabolism and blocking the occurrence of arterial hypertension.

What is the installation

Medical experts note that when acute renal failure, pulmonary edema or extensive intoxication of the body is detected, purification is carried out through a special filter that imitates a genuine kidney membrane.

The use of the device is justified if the kidneys have ceased to cope with the function of processing blood and removing harmful substances from the body. At the same time, the amount of toxins in the human body increases, which causes the death of brain cells. This happens due to insufficient oxygen supply to the brain.

Blood passing through the equipment is cleansed of harmful substances:

urea and its compounds;
creatinine (a product of chemical compounds in muscles);
poisonous compounds of mushrooms and plants;
medicines and narcotic drugs;
alcohol compounds (methyl and ethyl);
excess liquid.

The frequency and duration of the procedure depends on the stage of development of the disease and how advanced it is. Typically, the patient requires 2-3 sessions per week, which take approximately 4-5 hours. During this time, the concentration of urea in the body decreases by 70%, and the person’s overall condition improves.

Hemodialysis procedure

To carry out a hemodialysis procedure using a portable machine or stationary equipment in a clinic, it is necessary to carry out preliminary preparation of the patient. The fact is that many hours of pumping and pumping fluid through the patient’s vessels can significantly worsen their condition. As a rule, the blood vessels of such patients are already unhealthy, but the device will increase their wear and tear significantly.

To solve this problem, if a person’s blood vessels do not allow connecting equipment without harm to them, there are several solutions:

creating a hole in the body (it is formed from an artery and vein, its location is usually on the forearm);
sewing in a catheter (usually in the groin area, the operation is performed under local anesthetic).

After carrying out this or that procedure, the patient is strictly prohibited from physical strain and lifting heavy objects. The advantage of a catheter sewn into the body is the possibility of its immediate use.

Measuring pulse and pressure are considered necessary procedures, without which they will not be connected to the unit. New portable devices and medical equipment can take readings independently. A person should also measure their weight so that the doctor can assess tissue swelling and estimate the volume of fluid being pumped out.

Slag contaminants and toxins are forced out of the body by creating excess hydrostatic pressure in the vessels. By squeezing the liquid through a semi-permeable filter, the device completely cleans it and returns it back to the vessels, healthy.

The portable device is equipped with a small pumping station that supplies blood to a container with a filter. When it enters the reservoir, it is cleaned with a special solution and returns to the venous system without harmful impurities. After a few hours of operation of the device, the patient’s blood becomes clean. The procedure is often repeated after 2-3 days. This ensures the normal functioning of a person suffering from kidney diseases.

The procedure for cleansing the kidneys using hemodialysis is prescribed to the patient if the organs have lost their functionality and are working at only 10-15%. The violation is confirmed by the manifestations of unpleasant symptoms (vomiting, nausea, rapid fatigue, swelling). The device is able to take over part of the functions of the kidneys, while controlling a person’s blood pressure and normalizing the water-salt balance. There are a number of conditions when hemodialysis is necessary:

cessation of blood supply;
severe blood loss;
severe injuries;
infections after abortions;
inflammation of the kidneys with cessation of urine outflow;
blockage of the urinary arteries.

Before carrying out the cleansing, the attending physician assesses the patient’s well-being, determines the functionality of the kidneys, the condition of the respiratory system, liver, and heart. A prerequisite is laboratory blood tests.

Principle of operation

A hemodialysis machine cleans the patient’s venous blood of accumulated toxins and waste. To do this, the equipment must be connected to the patient’s veins and arteries. Using the built-in pump, the blood gradually moves to the membrane, and the dialysis solution for cleansing comes from the reverse side. The blood is cleansed from harmful substances with the help of a solution and, already healthy, it enters back into the system.

The equipment is filled with dialysate strictly before the procedure. The solution is prepared in advance, taking into account the individual characteristics of the patient. The device creates a composition from distilled water and a concentrated product independently. After the procedure, the effect of the drug is assessed by medical specialists based on several indicators.

Types of equipment

The desire to improve the quality of life and not “fall out” of the general rhythm drives all patients affected by kidney diseases. They want to work, take care of family and household chores, without being distracted for long. For these purposes, manufacturers have created a device - an artificial portable kidney. With the help of this device, the patient carries out cleansing in the familiar environment of his own home, independently, choosing the appropriate time.

However, the cost of this equipment is high and unacceptable for a large percentage of people. Therefore, doctors have other types of devices in their arsenal that are used in hospital settings.

Portable device

The portable artificial kidney was developed by Western scientists and was shown to the world just 10 years ago. The main advantage of the device is its weight of 3.8 kg and portable battery operation. The equipment works in a home environment, takes 4 hours, and the person feels much more comfortable than in the hospital.

The operating algorithm of this installation does not differ from the operating principle of stationary equipment. The blood is purified through a membrane using a solution. The connection occurs through a fistula or catheter and does not take much time. Cleaning, if necessary, is carried out around the clock.

How much does such a device cost? Today, a portable device is still very expensive and not everyone can afford to buy it.

Implantable device

Implants will soon become commonplace due to their widespread use in patients with chronic kidney failure. The dialysis unit is especially in demand due to the shortage of donor organs and the increasing cases of rejection of “living” organs by the patient’s own cells. This is a salvation for people suffering from incurable kidney pathologies.

Today, an American development company is conducting equipment research in professional laboratories. The compact device will perform filtration functions, cleansing the kidneys of harmful substances, toxins and waste. In this case, the energy necessary for the operation of the device will be generated due to the flow of blood. Information on how much such an installation will cost has not yet been reported.

Donor organ transplant

Chronic kidney failure is treated by transplanting a donor organ from another, healthy person. This is a surgical procedure where the patient's own organ is removed and replaced with a functioning kidney.
As a rule, replacement therapy is used in the last stages of the following diseases:

A donor organ transplant can prolong a patient’s life for a long time and improve the quality of life. This is a vital operation for children with congenital kidney problems, since constant hemodialysis inhibits the baby’s development.

Surgery is performed only in cases where the donor organ is suitable according to the patient’s criteria. Today, the percentage of organs that have not taken root is extremely high, so the development of artificial implants is considered a discovery that will allow medicine to reach a new level.

Contraindications for the procedure

Hemodialysis is a necessary procedure to maintain the life and normal existence of a large number of people suffering from severe kidney diseases. But not every patient is allowed to use the device; there are a number of contraindications:

severe arterial hypertension;
acute viral and bacterial infections;
bleeding disorders;
open tuberculosis.

Provided that the disease threatens the patient’s life, the artificial kidney apparatus is still connected, despite one or several contraindications. This decision is made to prolong the patient's life.