JPH0745407B2 - Plasma separation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for large-scale separation of plasma from human or animal blood which can be operated even at low pressure near zero.

[0002]

2. Description of the Related Art Conventionally, plasma is sometimes separated from blood in order to transfuse blood from a donor to another person or to handle the blood for some purpose.
First, blood is extracted, and then, a plasma is applied to a centrifuge to centrifuge plasma. Such a method is not only time-consuming, but also requires a great deal of manpower and complicated equipment and is troublesome to handle.

As a method for achieving the same purpose, a so-called "on-line type permeable plasma separation method" has been recently researched. According to such a method, blood is supplied to an on-line type separation device and the blood is separated from the blood. After separating the plasma, the plasma is temporarily stored, while the solute to be removed is treated and immediately returned to the blood supply source. This latest method is far simpler and more economical than the centrifugal plasma separation method described above in that blood is handled through a large amount of human hands, and that complicated equipment is used. is there. Moreover, when used for plasma treatment, most solutes to be removed are aggregated in plasma,
It has advantages over conventional methods that require a treating agent to be contacted with blood to remove solutes, such that blood can be cleaned quickly and easily.

In particular, the treatment material may be appropriately selected and used according to a predetermined treatment, and it is not necessary to consider the influence of the treatment material on blood cells. Moreover, since there is no interaction between the blood cells and the treatment agent, any treatment agent may be used as long as it meets the purpose. Since the treating agent used once can be easily separated from the plasma before sending it to the blood demand destination, the above-mentioned online membrane permeation plasma separation method is an extremely safe method, and it can be used in various fields. It is used.

As an example of such a plasma separation method, one disclosed in US Pat. No. 3,705,100 is known. The permeable membrane used in the plasma separation method disclosed in this U.S. Patent is a porous permeable membrane having a pore size of 0.1 to 0.8 microns. On the other hand, blood needs to flow at a rate of 2 to 50 feet per minute (about 61 to 1525 cm / min) while maintaining the transmembrane pressure difference at 1 to 15 psi. This method is believed to be effective in separating plasma from blood.

Another method is as follows: Vol. XXIV Tran Vol.
sactions American Society
Artificial Internal Orga
ns246, 1978) “Efficient Specif of Blood Tolerant Solvent System for Efficient Liver Function Reinforcement”
ic and Blood Compatible S
orient System for Hepatic
There is one that was announced by Mr. K. Ooichi and others under the title "Assist." According to this method, a cellulate acetate filter is used to separate plasma from blood. In use, blood is flown at a rate of 10 ml / min against a hollow fiber permeable membrane while the transmembrane pressure difference is applied. Is maintained at 60, 100 and 137 mmHg to separate plasma at a rate of 37 ± 2, 34 ± 2 and 32 ± 2 ml / min, respectively.

Recently, US Pat.
No. 911,182 discloses a continuous separation method of plasma by a so-called ultrafiltration method. According to such US patent, the permeable membrane is operated at a pressure of 50 to 700 mmHg. In general, if the transmembrane pressure is high, the cell composition of blood is easily destroyed, and it is necessary to adjust the transmembrane pressure to prevent clogging of the filter. ~ 700 mmH
It is disclosed that it is preferable to use a transmembrane pressure of 100 to 400 mmHg among the pressure of g.

[0008]

OBJECTS OF THE INVENTION The present invention is more efficient than the above-mentioned conventional methods, and does not cause destruction of blood cells or clogging of the filter, and at an extremely low transmembrane pressure. It is also an object of the present invention to provide a method of separating plasma from human or animal blood, which can be sufficiently carried out.

[0009]

The method for separating plasma from blood according to the present invention comprises:
The flow velocity is 5 along one surface of a separation membrane composed of hollow fibers having a large number of pores having a pore size of 0.1 to 0.6 micron.
-1500 cm / min, the depth is continuously supplied under conditions sufficient to separate plasma from the bloodstream, and at the same time, the positive pressure difference between the membranes of the separation membrane is controlled by adjusting at least the supply pressure of the blood. It is characterized in that the plasma contained in the blood is forcibly permeated through the separation membrane while maintaining the pressure just below 50 mmHg, and thereafter the plasma separated from the blood is sequentially taken out by the separation membrane. This is a newly created plasma separation method.

The plasma separation apparatus for separating plasma from blood used in the method of the present invention comprises a plasma separator 13 having a separation membrane made of a porous material having a pore size of 0.1 to 0.6 micron,
A blood supply pump 10 for supplying blood to one surface of the plasma separator 13 at a flow rate of 5 to 1500 cm / min and a depth sufficient to separate plasma from blood; and the plasma separator. The plasma reservoir 18 connected to the filtrate chamber side of 13 is used to set the positive pressure difference between the membranes of the plasma separator 13 within the range of just less than 50 mmHg, and the plasma in the blood is separated into the plasma separator 13 described above. It is composed of a plasma feeding pump 19 which is permeated through the plasma feeding pump 19 and a collector 23 for collecting the plasma separated by the plasma separator 13.

According to the present invention, when the transmembrane pressure difference is less than 50 mmHg, particularly when operated at a transmembrane positive pressure difference of 8.5 mmHg to less than 50 mmHg, the plasma separation rate exceeds 50 mmHg, contrary to most expectations. The above-mentioned object of the present invention is based on the finding that it can be increased as compared with the case of operating at a pressure difference, and the above-mentioned object of the present invention is suitable for separating plasma from blood, and , 0.1
Flow rate of 5-1500 cm at a depth sufficient to achieve blood plasma separation on one surface of a separation membrane composed of hollow fibers having a large number of pores of ~ 0.6 micron.
/ Min, while the transmembrane pressure difference is just less than 50 mmHg, especially 8.5 m in order to permeate plasma through the membrane
mHg to less than 50 mmHg, preferably about 40-20
It is achieved by maintaining the range of mmHg and collecting the plasma separated by such a separation membrane.

The method according to the present invention is different from the ultrafiltration method which is generally considered to increase the separation rate as the transmembrane pressure increases. Therefore, for the present invention, blood is a complex mixture of various particles,
In separating plasma from blood, common sense does not apply.

According to the present invention, it has been found that there is a further advantage when the plasma separation is carried out at a relatively low transmembrane pressure as described above. That is, blood is a very complicated fluid composed of various solutes, and the solutes have different particle sizes of molecules. Therefore, at present, the quality of plasma separation is judged not only by the amount of separated plasma, but also by the amount or composition of the filtrate. The amount of the desired component contained in the filtrate with respect to the amount of the desired component contained in is used. However, it has been found that not only can the amount of separated plasma be increased by carrying out under low transmembrane pressure, but also the sieving coefficient of various components of plasma can be increased. It was

The plasma separation device for carrying out the method according to the invention is suitable for separating plasma from blood,
Separation membrane means composed of hollow fibers having a large number of pores having a pore size of 0.1 to 0.6 micron and a flow rate of 5 to 1500
cm / min, a means for supplying blood to one surface of said separation membrane means in a depth sufficient to separate plasma from blood;
a means for permeating plasma in the blood through the separation membrane means and a means for collecting the plasma separated by the separation membrane means within a range of less than mmHg, particularly less than about 8.5 mmHg to less than 50 mmHg. It is configured.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. First, in FIG. 1, reference numeral 10 is a blood supply pump, the suction port of which is connected to a blood source via a pipe 11. On the other hand, the discharge port of the pump 10 is connected to the plasma separator 13 via the tube 12 having the bubble trap 12a.
Is connected to the entrance of. The downstream end of this separator 13 is
It is adapted to be connected to a bubble trap 15 via a pipe 14 and from the bubble trap 15 to a blood demand destination via a pipe 16. The filtrate chamber side of the separator 13 is connected via a pipe 17 to a plasma reservoir 18 and to a suction port of a plasma delivery pump 19. The discharge port of the feed pump 19 is connected to a processing device 21 such as a solvent cartridge and a pipe 23 via a three-way valve 20. The outlet end of the processor 21 is connected to the bubble trap 15 via the particle filter 22, while the tube 23 is a collector for collecting plasma for the purpose when needed, or further plasma. It is adapted to be connected to other parts of the device for processing.

Various modifications can be considered in the above-mentioned structure. For example, the plasma reservoir 18 can be incorporated into the separator 13 and the reservoir 18 need not be vented. In particular, when the reservoir 18 is not provided with a vent hole, it is necessary to control the discharge speed of the pump 19 to adjust the pressure in the reservoir 18, and thus the transmembrane pressure in the separator 13.

Most of the components of the separation device are known, such as blood supply pumps, plasma reservoirs, plasma supply pumps, solvent cartridges, particle filters and bubble traps. In particular, the plasma separator may also be one of various known filters and is generally unaffected by blood or blood components and is suitable for separating plasma from blood. It has a separation membrane made of different materials. As a material for the separation membrane, US Pat. No. 4,031,
Any of hydrophilic materials such as cellulose acetate, cuprophane, cellophane disclosed in No. 010, polycarbonate and polypropylene may be used. The polycarbonates mentioned are preferred.

The pore size is 0.1 to 0.6 micron, and the separation membrane in the separator is a membrane sufficient to separate, ie, filter, plasma from blood flowing along one surface of the separation membrane. Any arrangement may be used as long as the inter-pressure difference can be obtained.

The separation membrane composed of hollow fibers has a plurality of fibers, the inside of which communicates with the blood supply port and the outlet end of the separator, and the space around the fibers which communicates with the filtrate outlet of the separator. It is stored in the separator in the state vice versa or vice versa. In particular, it is desirable that blood be configured to flow inside each fiber. As a hollow fiber suitable for the present invention, a cellulose acetate hollow fiber sold by Asahi Medical Co. is preferable. In the parallel plate-shaped separation membrane and the hollow fiber, the latter is particularly the geometrical arrangement of the hollow fibers so that the dimensions do not collapse even when the transmembrane pressure required to obtain the desired plasma flow is applied. It is strong and therefore does not require a hollow fiber support.

Therefore, there are advantages that the structure of the separator as a whole is simple and relatively inexpensive. This advantage of using hollow fibers is especially necessary given the large effect that fluid dynamics have on the separation and sieving coefficients. That is, when a hollow fiber made of a porous material is used for the separation membrane, the size of the hollow fiber and the number of pores can be freely selected as required, and the plasma passage characteristics of the pores are improved to allow long-term use. Also, it is possible to prevent clogging and to easily adjust the membrane pressure of the separation membrane by freely setting the flow velocity of blood to the hollow fiber in a wide range. In particular, when the positive pressure difference between the separation membranes is extremely low, a particularly effective separation effect can be exhibited.

If the separation apparatus used in the plasma separation method of the present invention is used for the purpose of collecting plasma, the storage device 18
The plasma supplied from the pipe 23 is connected to a conventionally known plasma collector.
The three-way valve 20 may be set so as to be discharged via the. On the contrary, when the separated plasma is processed and immediately returned to the patient, the plasma supplied from the reservoir 18 is the processing liquid 21, for example, the adsorption cartridge, the particle filter 2 or the like.
2. The three-way valve 20 may be set so that it is returned to the patient via the bubble trap 15, and the tube 16. At this time,
During the flow from the three-way valve 20 to the bubble trap 15, the treatment agent particles contained in the plasma are filtered and removed, and thereafter, in the bubble trap 15, the blood supplied through the pipe 14 and the blood are supplied. Join.

If the separation apparatus used in the plasma separation method of the present invention is used for treating separated plasma, what kind of solvent is effective as the solvent in the cartridge 21 for removing undesirable components from the plasma? Anything is fine. U.S. Pat. No. 4,013,564 discloses a kind of such a solvent depending on its purpose.

When the separation apparatus used in the plasma separation method of the present invention having the above-described structure is operated under a certain condition of blood flow and under a certain transmembrane pressure, normal blood can be treated at a high rate. It has been found that it is possible to separate plasma and increase the sieving coefficient. The flow rate of blood through the separator should be chosen so that the flow rate of blood along one surface of the separation membrane in the separator is 5-1500 cm / min. Moreover, the sizes of the blood supply pump 10 and the separator are
Under the pressure condition on the downstream side when blood is being sent to the demand destination, and the pressure on the plasma side of the filtration membrane or the filtration means, that is, in the so-called open system, the atmospheric pressure or the pump 19 is provided. If the pressure is controlled by the pump 19 and is lower than the pressure on the blood side of the filter, the transmembrane pressure is just less than 50 mmHg, particularly 8.
It is necessary to select it within the range of 5 mmHg to 50 mmHg.

Preferably, the device according to the invention has a pressure range of 4
It is good to operate under 0 to 20 mmHg. In this way, the plasma separation rate, that is, the rate at which plasma can be separated from blood through the separation membrane can be maximized.
The transmembrane positive permeation pressure means the transmembrane permeation pressure which is the difference between the high pressure on the whole blood side of the filter and the low pressure on the plasma side of the same filter.

To prove this, an experiment was carried out using dogs. Dogs were used because dog blood resembles human whole blood, which has a normal protein content, so the results of experiments conducted using dog blood suggest that human blood should be processed. This is because it can be an index of the effectiveness of all the methods of the present invention. At any rate, blood was extracted from dogs in each experiment, and the extracted blood was treated with the device shown in FIG. 1 under the above-mentioned conditions. The pressure on the plasma side of the filtration membrane was atmospheric pressure, and the device according to the present invention was used as it was considered to be a so-called open system. The method according to the invention was applied to 3 normal dogs a total of 7 times. Of these, the N type plasma filter was used three times and the S type filter was used the remaining four times as the separator 13 shown in FIG.

Both the N type filter and the S type filter are hollow fiber type filters made of cellulose acetate sold by Asahi Medical Co., Ltd., having an inner diameter of 370 μm and a wall thickness of 190 μm.
m, the porosity is 84%, and the nominal pore size is 0.2 μm. However, in N type and S type, the number of fibers is 2500 and the effective length is 24 in N type.
0 mm, whereas the surface area is about 0.7 m ^2, intended for S type its effective length is the number of fibers 3300 this is 200 mm, the surface area both in that it is 0.75 m ² they are not equal.

The tubing used to connect the dog to the separator and to interconnect the components of the separator is sold under the trademark "LifeMed" by LifeMed Deviation, Inc. of Bernitron, USA. I used the one. Before operating the separation device, 40 ml of blood was filled in advance. Extraction of blood from dogs was performed from the femoral artery or internal carotid artery and then returned to the jugular vein or jugular vein. At that time, FC-100 cannula sold by Extracopolyol Co., USA was used. In treating the blood of each dog, 2 mg / kg heparin agent (manufactured by AH Robbins) was injected before the start of the experiment, and 0.5 mg / kg / hr heparin agent was injected in the rest of the experiment. Heparin was systematically added to the blood.

Further, by operating the pump 10, the blood supply amount to the separator was maintained at 100 ml / min. This pump 10 was a roller pump manufactured by Drake-Walcock Co., Ltd., and the above-mentioned blood supply amount of 100 ml / min was sufficient to make the transmembrane flow rate approximately 25 to 40 cm / min. The separation rate, the pressure at the inlet and outlet of the separator, and the pressure at the inlet and outlet of the solvent cartridge were measured periodically. The transmembrane pressure and flow rate are plotted in the graph of FIG. From the plot of each measured value, the curve drawn in the figure to show the tendency found experimentally in blood different from the true solution is also plotted when the transmembrane pressure exceeds 50 mmHg. To obtain one curve.

From the above, when the fluid is separated by the separator, unlike the normal state in which the flow rate of the filtrate passing through the filter decreases with the decrease of the transmembrane pressure,
As is clear from the graph of FIG. 2, according to the present invention, the amount of plasma separated through the separation membrane is lower than the pressure value conventionally considered to be the minimum transmembrane pressure when performing plasma separation. It is clear that it increases from a low place and reaches a maximum value when the transmembrane pressure reaches 30 mmHg. In view of this graph, transmembrane pressures suitable for achieving maximum plasma separation from normal whole blood are in the range of just less than 50 mmHg to about 8.5 mmHg, especially about 40-20.
It is clear that maximum efficiency is obtained within the range of mmHg.

The plot of the data on the minimum transmembrane pressure shows that the plasma flow rate is close to the maximum, but the minimum transmembrane pressure of 8.5 mmHg on the data achieves this maximum plasma flow rate. It is not an accurate pressure value. In other words, it is impossible to accurately know the pressure of 10 mmHg or less because the low pressure pulsating roller pump is used and the characteristics and measurement error of the measuring instruments used for various measurements are also related. . As the model name indicates, a pump does not operate at a steady pressure in the first place, and the maximum discharge pressure and the minimum discharge pressure have a difference equivalent to 10 mmHg which is customary for separating plasma from blood. May be accompanied. Therefore, each plot on the data was obtained by taking the average value of the pump pressure. Therefore, when the pump pressure is low (and therefore the transmembrane pressure at that time), it may be somewhat below the average value, which may be about 3.5 mmHg.

Moreover, the pressure gauge used is ± 2 at best.
It had an error of mmHg. In addition, the pressure of the fluid at the pressure measurement point also fluctuated, and in fact, the height of the mercury column fluctuated regularly at the time of measurement. Variables such as these errors are not important for high transmembrane pressure, but 10 mmHg
The following cannot be ignored. In view of the above, the transmembrane pressure can be even a positive pressure value close to zero, and even at such a transmembrane pressure close to zero, a higher plasma pressure than that generally expected can be obtained. The flow rate can be obtained. From the above, the method according to the present invention is
It can be carried out under a positive pressure of less than mHg. Furthermore, from the above, 8.5 mmHg, which is the lowest transmembrane pressure on the data, is only an approximate value, and in fact, it may be a much lower positive pressure. For this reason, in the present specification and claims, there is a description of “about 8.5 mmHg”,
This should be understood to include positive pressures below 8.5 mmHg.

From the above, when the fluid is separated by the separator, unlike the normal state in which the flow rate of the filtrate passing through the filter decreases with the decrease of the transmembrane pressure, the graph of FIG. As is clear from the above, according to the present invention, the amount of plasma separated through the separation membrane increases from a value lower than the pressure value which was considered to be the minimum transmembrane pressure in the conventional plasma separation. It is clear that the transmembrane pressure reaches the maximum amount of 30 mmHg. In view of this graph, the transmembrane pressure suitable for separating plasma from normal whole blood is just less than 50 mmHg, and the maximum efficiency is obtained particularly in the range of about 40 to about 20 mmHg. Is clear.

[0033]

As described in detail in the above embodiments, the present invention is
As a method of separating plasma from normal whole blood, whole blood is
A pore size suitable for separating plasma from the whole blood is 0.1 to 0.
A separation means composed of hollow fibers having a large number of 6 micron holes has a transmembrane pressure difference of just 50 mmH.
It is designed to allow only the plasma to permeate below g and it is possible to increase the separation rate of plasma as compared with the case where plasma is permeated by supplying whole blood at a relatively high pressure. The purpose of the term can be effectively achieved with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a plasma separation device used in the plasma separation method of the present invention.

FIG. 2 is a graph showing the plasma separation rate with respect to the transmembrane pressure.

[Explanation of symbols]

 10 ... Blood supply pump 13 ... Separator 18 ... Plasma reservoir 20 ... Three-way valve 21 ... Processor 22 ... Particle filter.

Claims (4)

[Claims] 1. A method for separating plasma from blood, wherein hollow blood having a large number of pores having a pore diameter of 0.1 to 0.6 micron is prepared by preliminarily pressurizing blood by a blood supply means.
Along the surface of the separation membrane composed of bars , the flow velocity is 5 to 15
The transmembrane positive pressure difference of the separation membrane is exactly adjusted by continuously supplying plasma at a depth of 00 cm / min and a depth sufficient for separating plasma from the bloodstream, and at the same time adjusting at least the blood supply pressure. Plasma contained in blood is forcibly permeated through the separation membrane while maintaining the pressure below 50 mmHg, and thereafter,
A method for separating plasma, wherein plasma separated from blood by the separation membrane is sequentially taken out. 2. The plasma separation method according to claim 1 , wherein the transmembrane pressure difference is in the range of about 8.5 mmHg to less than 50 mmHg. 3. A process according to claim 1 or arrangement as claimed in claim 2, about from the film between the positive pressure differential is about 20 mmHg 40
A method for plasma separation, which is in the range of mmHg. 4. The plasma separation method according to claim 1, wherein the hollow fiber is made of a hydrophilic material.