The ultrafiltration coefficient of the dialyzer. Clinical example of hemofiltration during rheumatism

17.05.2020

During hemodialysis, water under the influence of the hydrostatic pressure gradient inside the dialyzer moves from the blood into dialysate. The ultrafiltration rate depends on the pressure on the diarysor membrane (transmembrane pressure) calculated as blood pressure minus the pressure from the dialysate. The blood pressure in the dialyzer depends on the rate of blood pump and varies during the procedure in small limits. Thus, it is possible to control ultrafiltration to a greater extent by changing the pressure of dialysis fluid.

Fundamentally distinguish between the two ultrafiltration control systems are conditionally referred by pressure and by volume. The following is a brief description of the work of each system:

In the control system of UV on pressure with one pump, the choke limits the stream of dialysis fluid. With increasing rate of discharge pump, the pressure in the dialyissor will decrease.

In the control system of UV on pressure with two pumps, the discharge in the dialyzer is created due to increased, relative to the pumping pump of the discharge pump.

In the UV control system, the main element is the duplex pump its feature is that it simultaneously serves and takes the same amount of fluid from the dialyzer. In this case, the discharge is set by the ultrafiltration pump.

To the main disadvantage of systems with ultrafiltration control by pressure include the limitation on the ultrafiltration coefficient (KUF) of the dialisators used, which is explained by the measurement error of transmembrane pressure.

The ultrafiltration coefficient is the amount of fluid passing through the membrane in 1 hour per 1 mm Hg. Gradient transmembrane pressure

For example, when using a dialyzer with KUF 60 ml / h / mm Hg. and the accuracy of measuring TMR +/- 3 mm Hg. The error of the ultrafiltration system will be +/- 180 ml / h. The maximum value of KUF depends on the specific device of the hydraulic system.

For example, HD-SECURA using two pressure sensors before and after a dialyzer and having a special mode of operation with high-pixed membranes, can work with dialyissors with KUF to 60 ml / h / mm Hg. inclusive.

The disadvantages of the ultrafiltration control system in volume are: first, intermittent flow of dialysis fluid and therefore a decrease in the effectiveness of the procedure, secondly, the sensitivity to air penetration inside the closed circuit, which requires a special deaeration system.

Ultrafiltration control system

In the first models of hemodialysis devices, the measurement of a liquid removed from the patient during dialysis was not produced; The control was carried out only on the established TMR, the rate of removal of the fluid was determined approximately as a product of TMR on KUF. The essential error of this kind of calculation was caused: 1. The correspondence defined in vitro KUF values \u200b\u200bare real; 2. Reducing KUF during dialysis; 3. Inaccuracy of the definition of TMR.

Modern hemodialysis equipment automatically determines the rate of fluid removal and issues appropriate information on the scoreboard, which allows hemodialysis with a programmed change in ultrafiltration.

The possibility of conducting dialysis with the speed of the UV varied over the course of therapy in the case of sodium profiling has already been said. The second option of therapy is to vary the speed of UV with a stable (140-142 mmol / l) sodium concentration in a dialysis solution. The most popular procedure in which the SV speed in the first hour of dialysis is stepwise increases to a maximum, which is maintained for the first half of dialysis therapy, and then gradually decreases (to zero) at the end of the procedure. Naturally, the proposed therapy schemes are somewhat conditional and subject to individual correction In each case.

In the case of the UV control system in volume, the method of controlling ultrafiltrate is suggested by the design of the hydraulic part: counting the velocity of the pump UV.

In the case of an ultrafiltration control system for pressure, at least two options for controlling the remote fluid are possible. The first, when, on the basis of measuring the input and output flows of dialysis, it is concluded about the amount of ultrafiltrate received from the blood, and the second option, when the rate of removal of the fluid is judged by filling the special electrode chamber.

The error of the operation of the UV measurement system should not be worse than 50 - 60 ml / h. With a smaller value, it becomes indistinguishable on the background of the inaccuracy of the definition of the "dry" weight of the patient, food during dialysis and the introduced physiological solution.

As an additional improvement in the UV control system, you should mention the possibility of preventing reverse filtering.

It is believed that the dialysis fluid should not be completely sterile, because the diaralization membrane is a fairly efficient barrier for bacteria and their endotoxins. However, in case of certain conditions, the presence of bacterial products can play a negative role.

If dialysis is carried out at a low rate of ultrafiltration, then a change in the direction of pressure can be observed on a certain section of the dialyzer, and therefore the inverse filtration penetration of the dialysis fluid into the blood.

It is most susceptible to the inverse filtering of the part of the dialyzer, where the dialysis fluid is supplied, and the blood leaves the dialyzer. If reverse filtration occurs, then first of all in this place. Since the blood pressure is measured on all devices, a reasonable way to control reverse filtration is to install the dialysate input pressure sensor. Such sensors, for example, are installed in HD-Secura and DW1000. The machine issues an alarm when the input pressure of the dialysate is approaching the blood pressure, thereby preventing reverse filtering.

If, when using a standard membrane under reverse filtration conditions, the probability of penetration of bacteria and endotoxins is small (although such cases are noted), then when working under the same conditions with a high-pressure membrane, the sizes of the pores are relatively large, the probability of penetration of bacterial products into the blood increases, which can lead to undesirable side effects.

Another way to prevent possible consequences The penetration of bacterial products into blood is the installation of special filters of dialysis fluid to remove bacteria and endotoxins, as well as hemodialysis using a sterile dialysis solution.

Ultrafiltration is a way of correction of a water balance with an excessive amount of water in the body using the removal of removal of wasteless liquid from the bloodstream through special membranes, artificial or natural, acting as an ultrafilter. The artificial membrane is the gemofiltration and dialysis membrane, natural - peritoneum. Ultrafiltrate is the extracellular fluid, which is sent to the bloodstream under the influence of the oncotic pressure of plasma proteins.

Why hold the procedure?

Email swelling, brain
Heart failure of varying degrees of severity, non-measurable diuretic drugs or cardiac glycosides
Common Body Swells (Anasarka)
Nephrotic syndrome without renal failure
Operational interventions with artificial blood circulation or accompanied by hemodiliation
IN complex treatment Patients S. renal failureHemodialysis.

Risks of the procedure

Hypovolemia
Convulsive cuts of the muscles of the hands, legs
Pains in abdominal and spastic chest
Vomot
Voting witness
Reduced arterial pressure.

How to prepare for the procedure

The procedure is carried out only in the hospital. Before starting ultrafiltration is performed general analysis blood, urine, coagulogram, blood test for glucose content, syphilis and HIV infection, and electrolyte blood composition (potassium content, calcium, sodium, chlorine) in order to assess the statifies of renal or heart failure, gas and acid-alkaline composition is estimated blood.

How is the procedure

The procedure is performed in the patient's position lying on the back on the functional bed. Before the start of ultrafiltration for the prevention of blood coagulation, heparin is injected when it is filled with a dialyzer, the dose of which is calculated on a kilogram of body weight, in the process of performing a procedure, a constant infusion is carried out. The patient is connected to the dializer apparatus by puncture of the vein, which takes the blood and ultrafiltration. During the procedure, strict control over the mode is carried out, the speed is adjusted, the balance of fluid in the body is maintained. The effectiveness of the procedure is estimated to reduce the patient's body mass, the amount of exhausted fluid, eliminate the symptoms of hyperhydration.

Upon completion of the procedure for some time, the patient arises oliguraury.

The duration of the procedure is from 2 hours to 2 days. The volume of the removed fluid is up to 1-20 liters.

Results of the procedure

Removal of excessive liquid from the bloodstream, elimination of brain edema, lungs, permission of cardiac and renal failure.

Article author: Seed Maxim Nikolaevich

What is ultrafiltration?

Ultrafiltration is one of the methods of normalizing the aqueous homeostasis during an excess of fluid in the body. This method is based on the removal of shovel fluid from the blood, passing through artificial or natural membranes, which play the role of filter (ultrafilter). The most commonly used dialysis membrane, gemofiltration membrane or peritoneum (natural membrane). The main source of the formation of ultrafiltrate is considered extracellular fluid, which enters the bloodstream under the oppression of plasma proteins (proteins). The main difference from diuretic methods - ultrafiltration is capable of dosage dehydration and thereby preserves the electrolyte composition of the blood. Also preserved acid - alkaline blood condition. In the case of a sharp one-time removal of too much fluid, hypercalemia may develop, accompanied by metabolic acidosis, it is also possible to increase hematocrit and an increase in blood viscosity.

The process of ultrafiltration of fluid in the body is due to the presence of a filtration pressure between the filtration membrane. The pressure is only two: osmotic pressure (the desire of fluid to the transition from the region of a low concentration gradient to the region of a high concentration gradient) and a hydrostatic gradient. Based on this, two types of ultrafiltration are isolated: osmotic and hydrostatic ultrafiltration.

Ultrafiltration: Osmotic.

Osmotic ultrafiltration is used usually with peritoneal dialysis. To achieve the necessary effect, it is necessary to obtain osmotic pressure above, if the osmotic pressure in the blood. Only then ultrafiltration is possible. Most often used glucose. For example: in abdominal cavity Glucose solution is introduced with the content of glucose itself somewhat higher, if in the blood. Then, the fluid seeks from blood to the abdominal cavity, where it is pumped out. Thus, it is possible to adjust the water content in the patient's body.

Ultrafiltration: hydrostatic.

This type of ultrafiltration is carried out usually using a special dialyzer device. The dialyzer creates negative pressure between the hydrostatic pressure of the dialysis solution and hydrostatic blood pressure. Depending on this pressure, the rate of ultrafiltration can be adjusted. The permeability coefficient is calculated in the form of the amount of ultrafiltrate, which passes through the membrane in 1 hour of time. In the magnitude of such a coefficient, you can classify all dialyissors. They are small, medium and big permeability. The device of each device allows you to make the required speed and mode of ultrafiltration, which is very convenient. There are a number of devices that allow you to conduct independently ultrafiltration, while adjusting the process rate and the dialysis coefficient using electromagnetic flumetry.

Ultrafiltration with an active speed from 5 to 35ml / min allows you to eliminate high fluid delay in the body for only a few hours. But with the help of spontaneous constant ultrafiltration over the course of the whole day, it is possible to remove about 20 liters of fluid from the body.

Applicable to patients with heart failure, ultrafiltration is able to reduce the venous blood pressure and the central volume of blood to restore the health of the heart muscle. In patients with Uremia, ultrafiltration combined with hemodialysis is able to significantly increase the quality of blood purification, and it is not necessary to forget about the substitution infusion of fluid to the body. Emergency testimony for ultrafiltration is the edema of any organ or tissue. Ultrafiltration is also applicable to patients with renal failure. In such patients, the fluid delay is due to Oligira. However, the sequential use of ultrafiltration is due to the high risks of the collapse.

As for the contraindications, then with caution is used or refused in patients with hypovolemia, with hypotension (arterial), intersication of glycosides, and so on. pathologies.

Ultrafiltration - The method of correction of aqueous homeostasis in an excess of water in the body by removing removal of shifting liquid through natural or artificial membranes playing the role of ultrafilter. Most often, artificial dialysis and hemofiltration membranes are used as an ultrafilter. The source of the formation of ultrafiltrate is mainly extracellular fluid entering the bloodstream under the action of the oncotic pressure of plasma proteins. Unlike diuretics, ultrafiltration allows you to carry out dosage dehydration with a minor effect on the electrolyte composition and the acidic and alkaline state of the blood. In case of one-time removal of a large amount of liquid (several liters), a tendency to hypercalemia, metabolic acidosis, an increase in hematocrit and blood viscosity, accelerated azotemia gains.

Ultrafiltration of fluid in the blood is achieved by creating a pressure difference on both sides of the filter membrane: osmotic or hydrostatic. Accordingly distinguish osmotic and hydrostatic u.

Osmotic W. is usually carried out with peritoneal dialysis. To obtain effects it is necessary that the osmotic pressure of the dialysis solution is higher than the osmotic blood pressure. As osmotically active substance used mainly glucose by adding it to 1 l. Isotonic salts solution in the amount of 15, 25 or 42.5 g / l, that when the solution is introduced into the abdominal cavity, it allows you to get 200, 400 or 800 respectively ml Ultrafiltrate. 4-6 later c.When the difference between the osmotic pressure of blood and the solution disappears, the entire liquid from the abdominal cavity is removed. Selecting solutions for dialysis with a certain glucose concentration, regulate the water content in the patient's body.

Hydrostatic W. is usually carried out using a dialyzer, on the membrane of which a positive difference between blood pressure and hydrostatic pressure of a dialysis solution is created. From the value of this difference, called transmembrane pressure, as well as the rate of ultrafiltration depends on the permeability coefficient of the membrane for ultrafiltrate. The permeability coefficient is expressed by the amount of ultrafiltrate (in ml) passing through the membrane for 1 c. for each mm RT. Art. transmembrane pressure. In the magnitude of this coefficient, all the produced dialyissors are small (2-3 ml / mm RT. Art. in 1 c.), moderate (4-6 ml / mm RT. Art. in 1 c.) and big (8-12 ml / mm RT. Art. in 1 c.) permeability. The device of the devices allows you to install the necessary mode of W. According to electoral transmembrane pressure. Surveated from the last blood pressure, measured by the direct method in the venous bubble chamber, determine the pressure of the solution from the outer side of the membrane necessary to obtain the desired rate of ultrafiltration. The pressure pressure in the device is manually adjustable or automatically according to a given transmembrane pressure. There are devices in which management and control over U. are carried out on the principle of voluminometry or electromagnetic flumetry. The limit value of transmembrane pressure should not reach the quantity of the destructive pressure (approximately 600 mm RT. Art.).

Ultrafiltration with speed from 5 to 35 ml / min Eliminates a rather significant fluid delay for several hours. For some variants of the method, for example, using a constant spontaneous (due to blood pressure) arteriovenomous O., for 1 day. can be removed from the body 15-20 l. Liquid, completely eliminating edema.

Contraindications to the use of the method are hypovolemia, arterial, hypercalemia, metabolic acidosis, intoxication with cardiac glycosides, adrenal insufficiency.

Ultrafiltration is carried out only in the hospital. The procedure is performed in the patient's position on the function bed. Before starting the procedure, the patient introduces heparin at a dose of 15-30 units per 1 kg body masses to prevent blood clotting at the time of filling the dialyzer; In the process of ultrafiltration, a constant infusion of heparin at a speed of 10-15 units per 1 kg body masses per hour. Throughout the procedure, the ultrafiltration mode is controlled; If necessary, using special devices adjust its speed and maintain the balance of fluid in the patient. The effectiveness of the procedure is estimated by the amount of remote fluid, a decrease in the body weight of the patient, the reverse development of symptoms of hyperhydration. Special attention is paid to the dynamics of filling the tier veins, the frequency of the pulse and breathing, peripheral edema, ascites, hydrotorax, hydropericard, the size of the liver, wet wheezing in the lungs, a change in blood color in the extracorporeal system. For the objective characterization of the effectiveness of treatment in some cases, repeated radiography of organs chest, noted the dynamics of central venous pressure, the volume of circulating plasma and extracellular fluid. After W. Almost always observed Oliguria.

Complications in the process of V. may be hypovolemia, cramps in the muscles of legs and arms, spastic pain in the abdomen and chest, witness voices, vomiting. In the case of severe hypovolemia, a collapse can develop with loss of consciousness, generalized convulsions and stopping breathing. It should be borne in mind that a heavy collapse rarely happens the result of an error when conducting W., rather, it can be a manifestation of suddenly started internal bleeding, Tamponads of the heart, myocardial infarction, bacterial A, adrenal insufficiency. The threat of a collapse increases when carrying out U. in patients receiving b -adrenoblays and hypotensive drugs. Treatment of emerging complications is carried out immediately. Muscular cramps that have arisen before reaching the desired result of W., stop, without interrupting procedures, infusion 60-80 ml 40% Glucose solution, 20 ml 10% calcium solutions gluconate, 20-40 ml 10% sodium chloride solution. The first assistance in arterial hypotension is to in order to in a timely manner of the head end of the bed below the horizontal level, reduce the speed or stop ultrafiltration, slow down the arteriovenous blood perfusion. Then, based on the situation, infusion 500 ml 5% solution of glucose prepared on a polyionic basis (it is easier to perform through the arterial line of dialysis system using a pump); If necessary, introduce 200 ml 20% albumin solution, 30-60 mg. Prednisone, return blood from the device.

The invention relates to medicine, to cardiac surgery, to methods of ultrafiltration of blood under conditions of artificial blood circulation. It is carried out ultrafiltration of blood under artificial blood circulation by placing an ultrafilter supply line to the arterial line of the contour of artificial blood circulation, and the withdrawal of the ultrafilter line is placed in the cannula of the lower hollow vein. The invention contributes to a decrease in the number of intraoperative complications associated with the conduct of artificial blood circulation and ultrafiltration. 2 Tab., 1 il.

The invention relates to medicine, namely to cardiovascular surgery, in particular to methods for ensuring operations under artificial blood circulation in children. In children's cardiac surgery, after conducting artificial blood circulation, the accumulation of fluid in the extravasory space is observed. This leads to pronounced tissue edema and postoperative complicationsassociated with violations of the functions of various organs. The use of diuretics, cardiotonic drugs, the change in the scheme of artificial blood circulation does not give the desired effect. The method of treating swelling in cardiac surgical patients is ultrafiltration of blood (UV). Known classic method of ultrafiltration of blood under conditions of artificial blood circulation. It consists in passing the volume of circulating blood through an ultrafilter in order to remove excess fluid from the body. At the same time, UV is performed simultaneously with artificial blood circulation (IR). The Ultrafilter's aircraft line is installed in the arterial circuit of the IR apparatus, and the output is in the venous tank. Pressure in the filter, for ultrafiltration, is created by the pump. Unfortunately, classical ultrafiltration turned out to be not applicable in children's cardiac surgical practice due to hypovolemia. In the children's cardiac surgery there is also a method of ultrafiltration of blood, which is the closest to the resulting technical essence and achievable result. Proposed in 1991 Nike and Elliott. The authors called it modified. This method is selected as a prototype. Unlike the classic, in this ultrafiltration scheme, the location of the ultrafilter was changed. The inlet highway ultrafilter was installed in the aortic cannula, and the output - into the right atrium. In addition, ultrafiltration (UV) was carried out after the end of artificial blood circulation (IR). Such a scheme made it possible to maximize the length of the filter highways and by changing the time of the UV to avoid hypovolemia. The disadvantage of the proposed ultrafiltration scheme is the complexity of its conduct and the impossibility of ultrafiltration during artificial blood circulation. This increases the risk of complications related to bleeding and aerial embolismand leads to uncontrollable hemodilution, especially in children early age. The aim of the invention is to reduce the number of intraoperative complications associated with the conduct of artificial blood circulation and ultrafiltration. The goal is achieved by the fact that when conducting modified ultrafiltration, the ultrafilter supply line is placed in the arterial line of the contour of artificial circulation, and the ultrafilter shadow line is placed in the cannula of the lower hollow vein. New in the way is the location of the ultrafilter highways. The location of the supply line outside the aortic cannula significantly reduces the number of complications associated with the technique of IR. The location of the output highway in the cannula of the lower vein can avoid such traumatic manipulation, as the installation of this line of a separate line through the right atrium. This location of the highways allows the perfusionologist to collect an ultrafilter circuit, fill it, and also to carry out ultrafiltration, regardless of the actions of the surgeon during artificial blood circulation and after it. This allows you to hold the amount of hematocrit over the entire operation constant, regardless of the impact external factors (Cardioplegia, work of cardiotomic suns, etc.). Conducting ultrafiltration in the course of IR significantly reduces its time after the end of artificial blood circulation. Thereby, the risk of intraoperative complications associated with the conduct of artificial circulation and ultrafiltration is significantly reduced. In addition, the conduct of ultrafiltration in our scheme allows, if necessary, resume artificial blood circulation without additional renotelation. The drawing shows the scheme of the proposed method. The 2 Ultrafilter 1 supply line is connected to the arterial line of the IR circuit in place between the arterial air trap and aortic cannula. The output line 3 is mounted in the cannula of the lower hollow vein. The pressure in the filter, for ultrafiltration, is created by a special vacuum suction 5 and the pump 4. The outline above is collected, filled with liquid and blood simultaneously with the entire IR system. When the UV does not need, the supply line 2 is blocked. Pump 4 and vacuum suction 5 do not work. When carrying out UV, the supply line 2 is open, and the pump 4 and vacuum suction 5 begin to work. With this scheme, ultrafiltration is carried out in two modes: 1) simultaneously with the carrying out of artificial blood circulation and 2) after the end of artificial blood circulation. Example 1. Patient M., 2 years, diagnosis: congenital heart disease, interventricular septum defect. During the operation, plastics of the defect Time of artificial blood circulation was 1 hour. Modified ultrafiltration was carried out according to the method described in the prototype, i.e. The inlet highway was installed in aortic cannula, and the withdrawal is a separate highway in the right atrium ear. Below is a table 1, in which hematocrit is shown at various stages of the operation. Ultrafiltration time after IR amounted to 17 minutes. From Table 1, it can be seen how hematocrit falls at the operation steps. Such a reduction leads to violations of gas exchange processes between tissues and blood, acid-alkaline equilibrium, forces the use of cooling of the body. In addition, we draw attention to the considerable time of ultrafiltration after the end of IR. Example 2. Patient E., 3 years. Diagnosis: a defect of the interventricular partition. During the operation, plastics of the defect Time of artificial blood circulation was 1 hour. Modified ultrafiltration was carried out at the proposed method, i.e. the supply line was established in the arterial line of the IR system, and the output - in the cannula of the lower hollow vein. Below is Table 2, which shows the amount of hematocrit at various stages of the operation. Ultrafiltration time after IR amounted to 6 minutes. From the presented table, it can be seen that the magnitude of hematocrit in the steps of the operation, due to the timely conduct of UV during IR, is stable. Pay attention to a significant reduction in the time of the UV after IR. Thus, the implementation of UV on the new scheme makes it more secure, allows you to control intraoperative hematocrit and significantly reduces the time of ultrafiltration after IR. List of references 1. Elliott M.J. Perfusion for Pediatric Open Heart Surgery // Seminars In Thoracic and Cardiovascular Surgery.- 1990.- N2.- P. 332-340. 2. BODT J., Kling D., Bormann B.V. et al. ExtravascularLung Water and Haemofiltration During Complicated Cardiac Surgery // Thoracic and Cardiovascular Surgeon.- 1978.- N 35.- P. 161-165. 3. Naik S.K., KNIGHT A., Elliott M.J. A SUCCESSFUL Modification of Ultrafiltration for Cardiopalmonary Bypass in Children // Perfusion.- 1991, - N 6.- P. 41-50.

Claim

The method of modified ultrafiltration of blood under conditions of artificial blood circulation by passing the volume of circulating blood through an ultrafilter, characterized in that the supply line of ultrafiltrate is placed in the arterial line of the contour of artificial blood circulation, and the output line is in the cannula of the lower hollow vein.

Similar patents:

The invention relates to medicine and concerns the method of extracorporeal correction of the cellular blood cell composition in the treatment of diseases accompanied by a deterioration in the deformability of the patient's blood erythrocytes