Hemodialysis of the kidneys: types, procedure, indications and contraindications, how many live

Hemodialysis is a blood purification procedure performed with the help of the "artificial kidney" apparatus. This method allows you to quickly clear the blood of toxins and restore the salt balance. The main task of the kidneys is the filtration of blood and the withdrawal of toxic products with urine. However, with different diseases, the ability of the body to clean blood is markedly reduced. To perform purification outside the kidney and normalize the water and electrolyte balance, they resort to hemodialysis.

Hemodialysis of the kidneys

Hemodialysis is a process of purifying blood with the help of a special device, the so-called "artificial kidney".In general, it is a selective semipermeable membrane. The device may have a different design, but the principle of action remains the same: removal of substances from the blood by diffusion and convection.

• Diffusion is carried out in this way: on one side of the semipermeable membrane is the patient's blood, on the other - dialysis solution. Depending on the characteristics of the membrane from the blood into the solution, substances with a certain molecular mass, from metal ions to large protein molecules, can diffuse.
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• However, the diffusion method can not remove hydrophobic hazardous substances from the blood. For this, convection is used. It is conducted through the same membrane due to the difference in pressure between the blood of the patient and dialysate.
• Ultrafiltration is carried out by the pressure of blood on the membrane, created by means of a roller pump. In modern devices, this process is controlled by a computer. This procedure allows you to remove excess fluid.

Hemodialysis allows the purification of blood from the following substances:

• urea - a product of protein decay;
• of creatinine, an energy metabolism product;
• poisonous substances like strontium, arsenic, mushroom poison;
• various medicines: barbiturates, tranquilizers, iodine and bromine compounds, salicylates and so on;
• methyl and ethyl alcohol - therefore hemodialysis is prescribed for acute poisoning;
• excess electrolytes - sodium, potassium, calcium;
• excess water.

The essence of the hemodialysis procedure is as follows:

Indications for

Hemodialysis is prescribed in pathological conditions, when there is no other way to purify the blood of poisons.

These include:

• acute renal failure - with successful conservative treatment, you may need a single procedure designed to remove accumulated toxins. If the patient's condition does not improve, hemodialysis is performed daily until the patient is better;
• chronic insufficiency - while maintaining the functionality by 10-15% hemodialysis spend 3 per week. At 25% - 2 per week. The mode is adjusted depending on the patient's condition;
• pyelonephritis, acute glomerulonephritis;
• hyperhydration, representing a threat to life - pulmonary edema, cerebral edema. Here, hemodialysis is combined with conservative therapy. When life threatens, the first 3 sessions are conducted every day for 2 hours. Then hemodialysis is carried out 3 per week for 4 hours, while trying to remove 500 ml less liquid than in the first 3 days;
• for poisoning with poisonous substances as soon as possible, either 1 procedure lasting 12-16 hours, or 3 for 3-4 hours;
• drug poisoning - usually just one cleaning. In some cases, poisoning with a parasite, for example, an oil emulsion is used instead of a conventional dialysis solution;
• poisoning with methyl or ethyl alcohol - one procedure is carried out for 12-14 hours. In the first case, the level of methanol in the blood is 0.5 g / l;
• violations of electrolyte blood composition, life-threatening - prescribe 2-3 sessions per week 5-6 hours;
• with narcotic poisoning is enough 3 consecutive procedures during the day. If renal insufficiency has developed, then the appropriate course of treatment is prescribed.

The listed diseases and poisonings by themselves do not indicate the need for hemodialysis, there are other methods of purification.

Indication of this method is the blood and urine test:

• oligoanuria - daily urine volume does not exceed 500 ml;
• urea in blood plasma reaches 35 mmol / l;
• the level of keratinin in the blood reaches 1 mmol / l and higher;
• the content of potassium in the blood is more than 6 mmol / l;
• content of bicarbonate -20 mmol / l;
• the kidney performs its functions by no more than 10-15%-filters less than 200 ml of blood per minute.

Contraindications

Hemodialysis is not allowed in certain diseases and conditions. There are absolute and relative restrictions.

The absolute refers to:

• leukemia;
• cancer;
• anemia;
• severe mental illnesses like epilepsy, schizophrenia, acute psychosis;
• severe forms of CNS disorder;
• presence of 2 or more pathologies: cirrhosis, atherosclerosis, heart failure;
• age over 80 years;
• diabetes if the patient is over 70 years of age;
• alcoholism and drug addiction - in the absence of social rehabilitation of such patients, it is impossible to achieve any positive effect.

Relative restrictions include:

• tuberculosis in active form;
• ailments, fraught with massive bleeding - peptic ulcer, for example.

Types of

It is possible to conduct hemodialysis with kidney disease not only in the clinic, but even at home. But, the truth, practice is so widespread basically abroad. In Russia, for the passage of blood purification, patients can come from another area, so the classification of methods is rather arbitrary.

Hemodialysis at home:

• there are special portable devices designed for "home" use. The most modern of them are dressed in a belt and weigh from 4 to 7 kg. Hemodialysis is carried out every day or night, the duration of the procedure is 2-4 hours. In European countries and the United States, this option is considered to be a very effective alternative to outpatient treatment and is very common;
• refers to the merits of such a method of security, since only one person uses the device, ease of handling, convenience, since cleaning is carried out at the right time and there is no need to wait in line;
• to the minuses of the solution include the cost of hemodialysis - about 15-20 thousand dollars, the need for training and supervision of a medical worker for the first time.

Video home hemodialysis:

Outpatient hemodialysis:

• in special outpatient centers carries out hemodialysis in chronic or acute renal failure. Procedures are carried out in the order of the queue, usually 3 per week duration of 4 hours. Use for this purpose apparatus more specialized;
• the main advantage of the method is the observation of a doctor, the ability to control the result, passing the tests, and the opportunity to adjust the treatment. The device provides adjustment of circulation speed, control of volume, pressure, hemoglobin level and hematocrit;
• minus is the need to wait in line and get to the outpatient center.

Hemodialysis inpatient treatment:

• in hospitals there are around-the-clock offices, equipped with the required equipment. The procedure is no different from an outpatient procedure;
• plus - continuous monitoring by a physician;
• minus the need to stay in the hospital. In addition, there is a small but possible possibility to get infected with hepatitis B.

Another procedure classification is used, connected with the functionality of the device itself.

• Regular hemodialysis involves the passage of blood through a cellulose membrane with an area of ​​up to 12.5 square meters.m. The material has a small permeability, so that a small molecule passes through the filter. The speed is not high - 200-300 ml / min, the vigilance of the procedure is 4-5 hours.
• Highly effective - the membrane is a more modern material with an area of ​​up to 2.2 square meters.m, which allows you to increase the flow of blood to 350-500 ml / mi. At the same time, dialysate passes through the membrane at a speed of 600-800 mg / min. The procedure in this case lasts 3-4 hours, and the cleaning result is better.
• High-precision hemodialysis - it is based on a highly permeable membrane, which transmits large organic molecules. Thus, it became possible to increase the lists of toxic substances that need to be removed from the blood. However, more substances enter the bloodstream from the dialysate, so that the quality of the solution needs to be monitored.

However, these data should be considered very approximate, since such kind of evidence studies in the Russian Federation were not conducted, and information was obtained only about registered patients. In connection with this, the increase in outpatient and inpatient departments with the apparatus "artificial kidney" - or programmed hemodialysis, acquires great urgency.

Carrying out the procedure

Purification of blood outside the kidney requires the fulfillment of three main conditions.

• Incomplete blood - this problem is solved by the introduction of a special safe drug - heparin. It prevents the formation of blood clots.
• Access - the cleaning mode is assigned by the doctor. This can be a daily procedure lasting 2-3 hours or 2 sessions a week for 6 hours. Most often, hemodialysis is carried out three times a week. With this intensity, access to the veins and arteries should be easy and constant. Provide this in 3 ways:
  • fistula - the artery and vein are connected directly to the vessels, usually on the forearm: the brachial artery and the vein in the elbow fold. Fistula ripens from 3 to 6 months, after which dialysis needles are injected into it;
  • graft is a synthetic tube that does the same. This device is usually used in the early stages and with a relatively short duration of treatment. You can use the graft after 2-6 weeks. The state of the vessels does not change, but the method itself is fraught with complications;The
  • catheter is a temporary solution that is used for urgent intervention.
• The third condition is the "artificial kidney" apparatus itself. The design of it over time has changed little, although the device has become much more compact, but the membranes have been used different. It is the nature of the membrane and allows you to make hemodialysis as effective as possible.

The structure of the "artificial kidney"

The hemodialyzer consists of 3 main working modules:

• The blood processing unit includes:
  • pump for pumping blood;
  • pressure sensors - arterial and venous;
  • device that prevents the appearance of bubbles;
  • pump for the supply of heparin, a preparation that prevents coagulation.
• The dialysate unit includes:
  • air removal system;
  • solution temperature monitoring system;
  • system for mixing;
  • sensor for monitoring blood leakage into the dialyzer;
  • filtration control system.
• The third block is actually a filter with a hemodialysis membrane.

The principle of operation is simple: the "artificial kidney" is supplied with blood from the vein - the device is connected through a dialysis needle in the fistula. A semi-permeable membrane is installed in the hemadializer, blood circulates on one side of the membrane, and dialysis solution on the other side. Both liquids are pumped with pumps at a certain rate - no more than 450 ml / min for blood and about 500 ml / wines for dialysis solution. Through the membrane of the blood extracted toxic substances and metal ions, usually sodium. The composition of the dialysis solution should be as close to the plasma as possible so that by regulating the level of potassium and sodium it is possible to correct the number of ions in the blood.

The procedure effectiveness sensor usually serves the level of urea in the blood after purification. If hemodialysis is performed 3 per week, then the urea level should decrease by at least 65%, if 2 - not less than 90%.

Types of apparatus

From a functional point of view, hemodialisers differ mainly in the nature and area of ​​the membrane. Of course, the level of technicality of dialyzer units is also important: in modern apparatus dialysis solution is prepared by the machine itself in accuracy. In addition, the control system in such equipment is much more perfect and allows not only to monitor the level of pressure or hemoglobin change, but also to correct the composition of the dialyzer.

This applies mainly to stationary cumbersome installations used in clinics and outpatient centers. The recognized leaders of this area are the devices of Swedish and German concerns: "WAHTER-1550", "NIPRO SURDIAL", "Dialog Advanced" and "Dialog +" from B / Braun, GAMBRA.The possibilities of portable, especially designed for wearing on the belt, are severely limited.

According to the nature of the membrane, there are two types:

• Plate - the filter is a series of plates arranged parallel to each other and covered with a membrane. Between the plates circulates dialysate, the blood washes the membrane from the outside. With this structure it is easy to control the level of filtration, a lower dose of heparin is required, since the resistance to blood flow is low. In addition to filling the dispenser you need a small amount of blood, which relieves the patient of the associated complications.
• Capillary - a set of hollow fibers, each of which is a bundle of 10 thousand thin capillaries with a diameter of 0.3 mm. Blood flows into the capillaries, and the dialyzer circulates around the fibers. Children and adults at the beginning of procedures are prescribed a more gentle method: blood and dialyzer flow in one direction, thus reducing the rate of blood supply. For the fastest cleansing, the blood and dialyzer are directed in opposite directions.

Diet

The results of hemodialysis largely depend on nutrition. In this case, non-observance of restrictions negates all the efforts of physicians in the literal sense of the word. Individual diets are prescribed, since it is important to take into account the recommendations of both the nephrologist, the endocrinologist, and the cardiologist. Usually, the food corresponds to the diet tables 7a and 7b.

Principles of the diet for hemodialysis are as follows:

• restriction in the use of table salt - 2 g per day;
• decrease in products rich in potassium - dried fruits, chocolate, nuts, bananas, potatoes and others;
• reduced animal protein intake and transition to vegetable. Dairy products - kefir, cottage cheese, are allowed;
• excludes from the diet any products leading to fluid retention: pickles, smoked products, alcohol, coffee, cocoa and the like;
• is necessary to monitor the level of calcium and phosphorus;
• sweets are allowed in a moderate amount if the diagnosis is not complicated by diabetes;
• The most difficult factor, as practice shows, is the restriction of liquid, It is assigned individually, because it depends on the degree of fluid retention and its quantity. Moreover, not only the consumed liquid, but the liquid obtained from solid food - the same vegetables or fish - is included in the drinking regime.

It is necessary to monitor the body weight: a set of 2-2.5 kg in the period between the rates of hemodialysis indicates imbalance and excess calories.

Products with a low content of potassium are allowed: apples, tomatoes, beets, melons, cucumbers and so on. Vegetables prefer to cook and grind. Meat and fish are lean. Method of cooking: allowance, cooking, steaming - the best way of cooking.

The food is fractional - up to 6 times a day.

Complications of

The blood purification procedure is far from as safe and simple as we would like. Blood pumping, a temporary deficit that the body senses during cleaning, a fairly sharp change in composition, even for the better, all have an unfavorable effect on a person. So, vomiting, nausea, dizziness and convulsions are quite common.

However, hemodialysis can lead to more serious complications. The fact is that during hemodialysis the kidney function is performed by an artificial device. But the latter performs only filtering, and all other functions of the organ are not performed.

This "inactivity" of the kidneys can lead to the following complications:

• arterial hypertension is provoked by that very temporary blood deficit. And the pathology of the kidneys is a direct "reason" for increasing blood pressure;
• anemia - the basis is the lack of erythropoietin, produced by healthy kidneys;
• CNS damage - or peripheral neuropathy, numbness and loss of limb sensitivity;
• dystrophic bone disease - due to the inability to absorb calcium and phosphorus, since the latter are not converted to the desired compound;
• pericarditis - inflammation of the cardiac membrane, associated with the accumulation of fluid in the heart;
• increase in the level of potassium in the blood - as a rule, is the result of non-compliance with diets against hemodialysis;
• dialysis syndrome is an epileptic attack, triggered by a decrease in osmotic blood pressure.

In the treatment of renal failure, usually 3 procedures are prescribed per week. After the improvement - the kidney function is at least 10%, the number of procedures is reduced to 1 per week. If the patient carries out hemodialysis at home, the number of procedures is usually greater, but here everything depends on the effectiveness of the treatment.

Very often, the cause of death of such a patient is not renal failure, but the development of complications, and most often they are provoked by a malfunction of the equipment, the appearance of a blood clot or a poor-quality dialysate.

No less frequent reason is the lack of financial opportunities. On average, the procedure of hemodialysis costs 6-8 thousand rubles, which forces many patients to reduce the number of necessary procedures, and even completely refuse them.

Hemodialysis is not a panacea. This procedure can save a life at an acute poisoning and will save from self-poisoning in those cases when the kidney temporarily refuses. However, in chronic renal insufficiency, hemodialysis, along with such factors as nutrition or the motor regimen is a supporting agent and how many patients live on an artificial kidney, depends on each specific case.