PLASMA EXCHANGE

From Big Medical Encyclopedia

PLASMA EXCHANGE, cytapheresis (plasmapheresis; grech, plasma molded, issued here — a liquid part of blood + aphairesis otnyaty, removal) — a method of removal from whole blood of its components — plasmas (plasma exchange) and cellular elements (cytapheresis).

In 40 — 50 20 century received components of blood after spontaneous sedimentation of cellular elements (natural gravitation) during 18 — 24 hours in glass bottles or plastikatny bags (containers). By such method it is possible to receive from one donor along with plasma and eritrotsitny weight (see) the leukocyte suspension containing (1,7 — 2,2) X 10 9 leukocytes in volume apprx. 25 ml (see. Leykokontsentrat ). Afterwards began to apply methods at which acceleration of natural sedimentation carried out by addition in blood of various substances, sedimentiruyugtsy erythrocytes (dextrans, polyvinylpirrolidone, gelatin, etc.), or fibrinogen, a fikol, ion-exchange pitches, and also a glass beads or cotton wool. However the listed methods were a little effective, demanding big expenses of time.

In the 60th 20 century methods of division of blood by means of centrifuging (artificial gravitation) gained distribution in glass bottles or plastikatny bags, at the same time division of blood into plasma and eritrotsitny weight makes at a temperature — 22 ° within 20 min. and artificial gravitation of 790 — 980 g. Thrombocytes allocate (plateletpheresis) by two consecutive centrifuging: in the beginning centrifuge a whole blood in glass bottles within 10 — 15 min. (250 — 300 g), then the plasma enriched with thrombocytes within 25 — 30 min. (550 — 700 g). The received bottom sediment of a bottle is resuspended in 30 — 50 ml of plasma. Trombotsitaferez in plastikatny bags make similarly, having changed the size of artificial gravitation and time of centrifuging — the first centrifuging make within 15 min. (470 g), the second — within 30 min. (2600 g). An exit of thrombocytes at the same time makes (50 — 80) * 10 9 from one dose of stored blood (450 ml). Leukocytes receive by triple centrifuging of blood in bottles or plastikatny bags within 10 min. (250 — 300 g), taking (2,0 — 2,7) X 10 9 leukocytes from 450 ml of stored blood. However the listed methods are labor-consuming and do not allow to receive sufficient for to lay down. effect of quantity of thrombocytes and leukocytes.

the Diagrammatic representation of extracorporal system for a plasma exchange — a cytapheresis: the whole blood from an elbow vein of the donor (I) with solutions of anticoagulants is fractioned in a separating bowl on leukocytes, erythrocytes and plasma (with thrombocytes), the allocated leukocytes gather in a container; for department of thrombocytes a part of plasma is in addition centrifuged for the purpose of receiving a concentrate of thrombocytes and plasma which can be returned together with erythrocytes to the donor (II).

From 70th 20 century there were devices fractionators of blood which allowed to receive necessary quantities of all components of blood, to reduce thanks to a special design of a separating bowl impact on cells during the centrifuging. There are two types of fractionators of blood. In one (PF-0,5, Aminko, Fenval, IIBM) process of capture of blood at the donor or the patient, its divisions into components, their withdrawal and return of the rest of blood to a blood channel is carried out continuously, in others (PK-0,5, «Gemonetpks», Eellko) process nospt discontinuous character. In fractionators of continuous action for division of blood create the extracorporal circle of blood circulation including a rotor of the device and system of plastikatny tubes (fig). Under the influence of perpo-staltichesky pumps blood through the catheter entered into an elbow vein comes to system of plastikatny tubes where mixes up with anticoagulants (see), then comes to a rotor of the device. In a rotor there is a division of whole blood into eritrotsitny and plasma fractions, at the same time leukocytes are located on both sides from border of eritrotsitny and plasma fraction (granulocytes are preferential in eritrotsitny fraction, and lymphocytes and thrombocytes — in plasma). Through a transparent cover of a rotor it is possible to watch formation of plasma and eritrotsitny fractions, and also fractions of leukocytes on condition of their high concentration in blood, napr, at patients hron. myeloleukemia, hron, lymphoid leukosis. Through an average opening of a rotor carry out allocation of a necessary component of blood — plasma, leukocytes, erythrocytes — in a plastikatny bag. Thrombocytes at the same time receive from plasma, to-ruyu collect in the plastikatny bag (volume of 300 ml) containing 45 ml of anticoagulant after additional centrifuging on the refrigerator centrifuge within 5 min. (5000 g). The concentrated thrombocytes resuspend in 30 — 50 ml of plasma. Would receive for one such operation — 8 containers with concentrates of thrombocytes.

Thanks to the design of a rotor allowing to divide blood with the small force of impact (18 — 105 g) on cells, this method of fractionation causes insignificant traumatization of uniform elements of blood. The fractionator is provided with an alarm system and blocking of pumps for prevention of an air embolism. Bottles with anticoagulants are on the weight sensors giving light and sound signals and blocking pumps when the fluid level decreases to critical. There is also weight sensor on a tube on which blood from a rotor is returned to the patient.

In a rotor of fractionators of the second type blood is divided into components — plasma, thrombocytes, leukocytes and erythrocytes. Division happens in the vertical plane. In process of accumulation in a rotor of erythrocytes from it plasma, thrombocytes and leukocytes are consistently forced out, to-rye gather in plastikatny containers. After filling of a rotor with erythrocytes stop capture of blood, exempt a rotor from erythrocytes return motion of the pump. Then the remained components of blood return in an elbow vein of the donor and carry out the following cycle. In the course of operation make 6 — 8 such cycles. Owing to the discontinuous nature of process of fractionation considerable volumes of blood in one step appear out of circulation; at this way a little smaller concentration of cells is taken, but their safety funkts, properties, despite the big force (g) operating on cells at fractionation is ensured.

Using devices for fractionation of blood, allocate its components from the healthy donor, to-rye find broad application in to lay down. to practice (see. Hemotransfusion ). At a leykotsitafereza it is possible to receive from the donor in one step in 300 — 500 ml of a concentrate (10 — 70) of X 10 9 leukocytes, (5 — 50) X 10 9 granulocytes, (5 — 8) X 10 9 lymphocytes; at a plateletpheresis — (200 — 800) X 10 9 thrombocytes in 100 — 200 ml of a concentrate. Make also fractionation of plasma for receiving drugs from plasma (cm. Blood plasma ). The plasma exchange and a cytapheresis apply at patients with the medical purpose, napr, to removal of leukemic cells at a chronic lymphoid leukosis, a myelosis. At the same time it is in one step possible to allocate to 1000 X 10 9 leukocytes that gives a good wedge, effect. By means of fractionators of blood produce plazmoobmen (3 — 5 l) and exchange of erythrocytes (up to 2 — 3 l).

As together with plasma it is possible to remove a large number of a paraprotein, P. apply in urgentny therapy of a hyper viscose syndrome at patients with Valdenstrem's macroglobulinemia (see. Valdenstrema disease ) and multiple myeloma (see). Massive P.'s use for patients with autoimmune thrombocytopenia, autoimmune hemolitic anemia, at an izoymmunization to a Rhesus factor and some other immune diseases allows to reduce considerably the level of antibodies and to improve a condition of patients. A number of researchers with success make exchange of plasma at a hepatic coma and poisonings, exchange of erythrocytes — at treatment of a sickemia.

Contraindications for patients and donors to P.'s carrying out and a cytapheresis the cardiovascular, renal, liver failure, deep anemia and thrombocytopenia with a hemorrhagic syndrome, positive tests on the Australian antigen and syphilis or symptoms of some other inf serve. diseases. And a cytapheresis approach P.'s appointment individually, considering character of a course of a disease and the carried-out treatment.

At P.'s carrying out and a cytapheresis there can be complications. According to Mac-Kredi (K. V. of McCredie, 1974), removal of large volumes of plasma in combination with introduction as anticoagulant of citrate solution in 15 °6 cases leads to a hypocalcemia, the shown tremor, concern, pallor, paresthesias; in more hard cases spasms, hypotonia, tachycardia, disturbances of a cordial rhythm join. On an ECG otmechav»! lengthening of an interval S — T, decrease and inversion of a tooth of T. For prevention of a complication introduction of a gluconate of calcium is recommended. At overdose of the heparin used as anticoagulant the hemorrhagic syndrome can develop. During the carrying out a plasma exchange and cytapheresis in case of lengthening of a blood clotting time introduction a protamin-sul-veil is recommended.

At a low temperature indoors, transfusion of cold solutions and return to the patient of the cooled components of blood it can have reactions in the form of disturbance of a cordial rhythm, emergence of cold-reactive antibodies. At the high temperature indoors which is combined with removal of large volume of plasma there can be a hypovolemic syndrome (see. Oligemiya ). For prevention of these reactions it is necessary to maintain optimum air temperature (21 — 23 °). At hemotransfusion (see), plasmas, blood-substituting liquids and other solutions in the course of P. and a cytapheresis development of the pyrogenic and allergic reactions is possible. Transfusion of large volumes of these liquids exceeding the volume of the removed plasma can lead to an overload of the right departments of heart. It demands the strict accounting of amount of the entered solutions according to a dose of the withdrawn plasma.



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H. H. Kalinin.

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