JP6745027B2 - Device for removing microbubbles in blood and cardiopulmonary system - Google Patents

Description

The present invention relates to a device for removing microbubbles in blood. In particular, the present invention relates to a microbubble removing device that can be preferably used for removing microbubbles mixed in blood in the extracorporeal circulation. Furthermore, the present invention relates to a cardiopulmonary system including the microbubble removing device.

In cardiac surgery, an extracorporeal blood circulation circuit, including an artificial lung, is used to arrest the patient's heart and act on behalf of the respiratory and blood circulation functions during that time. In recent years, in cardiac surgery, a gaseous microemboli (GME), in which microbubbles in blood occlude a capillaries of a patient to form an infarction, has attracted attention. This is said to be the cause of brain dysfunction represented by postoperative memory deficits.

As a method for removing air bubbles in blood, a filter-containing type artificial lung in which a filter for removing air bubbles is provided on the downstream side of the gas exchange unit is known (for example, see Patent Document 1).

International Publication No. 2015/046224 Pamphlet

A screen filter is generally used as a filter incorporated in the artificial lung. When the pore size of the screen filter is reduced, the ability to remove bubbles is improved, but the passage resistance of blood is increased. Therefore, a general filter incorporated in the artificial lung cannot sufficiently remove the microbubbles of 50 μm or less, which are the cause of the gaseous microemboli.

An object of the present invention is to provide a microbubble removing device and a cardiopulmonary system having excellent ability to remove microbubbles in blood.

The device for removing microbubbles from blood according to the present invention is a defoaming device including a housing provided with a blood channel and a hollow fiber membrane provided in the housing so as to come into contact with blood flowing through the blood channel. And a decompression means for decompressing the inner cavity of the hollow fiber membrane. The cross section of the blood channel is circular. The hollow fiber membrane is arranged so as to cross the blood channel. The microbubble removing device is configured to remove microbubbles flowing through the blood flow path together with blood by depressurizing the inner cavity of the hollow fiber membrane.

The cardiopulmonary system of the present invention comprises a blood removal line for removing blood from a patient, a blood reservoir for temporarily storing blood removed through the blood removal line, and blood for delivering blood in the blood reservoir. A pump, an artificial lung that performs gas exchange for blood from the blood pump, the microbubble removing device of the present invention that removes microbubbles in blood that has passed through the artificial lung, and the microbubble removing device And a blood return line for returning the blood passing through the patient to the patient.

According to the present invention, by depressurizing the lumen of the hollow fiber membrane, a pressure difference is generated between the inside and the outside of the hollow fiber membrane to remove gas in blood. As a result, it is possible to remove micro bubbles that are difficult to remove with a general filter. Therefore, the removal device and the cardiopulmonary system of the present invention have excellent ability to remove microbubbles in blood.

FIG. 1 is a perspective view of a defoaming device that constitutes a microbubble removing device according to an embodiment of the present invention. FIG. 2 is a sectional view of the defoaming device shown in FIG.

The microbubble removing device of the present invention includes a defoaming device in which a blood flow path is provided in the housing. A hollow fiber membrane is provided in the housing so as to come into contact with blood flowing through the blood flow path. The space on the side opposite to the blood with respect to the hollow fiber membrane (that is, the inner cavity of the hollow fiber membrane) is decompressed by the decompression means. Since the pressure difference between the inside and outside of the hollow fiber membrane (that is, between the blood (liquid) side and the gas side (inside the lumen)) is utilized to selectively remove the gas that constitutes microbubbles in the blood. is there. Since the hollow fiber membrane is used, it is possible to remove microbubbles that are difficult to remove with a general screen filter. Therefore, the removing apparatus of the present invention is excellent in the ability to remove microbubbles in blood. The problem that the passage resistance of blood increases, which may occur when a screen filter is used, does not substantially occur in the present invention.

As a method for removing microbubbles in blood by utilizing the pressure difference between the inside and outside of the hollow fiber membrane, unlike the present invention, the pressure in the blood (liquid) side is increased to remove the gas in the blood from the hollow fiber. A method of removing it through a film can be considered. However, increasing the pressure of blood is likely to cause an increase in blood pressure loss and blood cell destruction (hemolysis). In the present invention, the outside (the blood (liquid) side) of the hollow fiber membrane is not made to have a high pressure, but the lumen (gas side) thereof is depressurized. Therefore, it is possible to remove the microbubbles in the blood without causing the above-mentioned problems when the blood side has a high pressure. At the same time, it has an additional effect that foreign substances (including thrombus) in blood can be captured and removed by the hollow fiber membrane.

The hollow fiber membrane is a porous membrane having a large number of fine pores formed therein and has a hollow cylindrical shape. Gas can pass through the fine pores of the hollow fiber membrane, but liquid (blood) cannot pass through. The area of the surface of the hollow fiber membrane that comes into contact with blood and the gas-liquid separation characteristics (for example, the opening diameter and opening degree of the micropores) are not limited, and can be set appropriately according to the blood flow rate, the amount of microbubbles mixed, and the like. ..

In one embodiment, the hollow fiber membranes may be used in the form of hollow fiber membrane bundles composed of multiple hollow fiber membranes. The hollow fiber membrane bundle can be arranged so as to cross the blood flow path. Blood passes between the hollow fiber membranes. The lumen of the hollow fiber membrane is decompressed by the decompression means. According to this embodiment, it is possible to realize a defoaming device having a small and simple structure and excellent in the ability to remove microbubbles. Hollow fiber membrane bundles are widely used as members that exchange gas with blood in artificial lungs. The hollow fiber membrane bundle for the artificial lung can be used as it is or after making a slight design change, as a gas-liquid separation membrane of a defoaming device.

In one embodiment, one end of the hollow fiber membrane is sealed and the other end of the hollow fiber membrane is in communication with the pressure reducing means. According to this embodiment, the inner cavity of the hollow fiber membrane can be decompressed with a simple structure.

In one embodiment, the decompression unit decompresses the inner cavity of the hollow fiber membrane so that the pressure difference between the inside and the outside of the hollow fiber membrane is 50 kPa or more, and further 80 kPa or more. The larger the pressure difference between the inside and the outside of the hollow fiber membrane, the better the ability to remove microbubbles. As described above, according to the present invention, the blood side is not made to have a high pressure to remove the microbubbles. Therefore, even if the above-mentioned pressure difference becomes large, an increase in blood pressure loss and blood cell destruction do not occur. The upper limit of the pressure difference is not limited, but preferably 200 kPa or less, more preferably 150 kPa or less. If the pressure difference is larger than this, not only the removal ability of the microbubbles does not improve as expected, but also the cost for realizing such a pressure difference increases.

The pressure reducing means is not limited as long as the above pressure difference can be realized, but for example, a known vacuum pump, roller pump, or the like can be used. A known pressure gauge (for example, a manometer) can be used to control the pressure difference between the inside and the outside of the hollow fiber membrane.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. However, it goes without saying that the present invention is not limited to the following embodiments. Each drawing referred to in the following description is a simplified view of main members constituting an embodiment of the present invention for convenience of description. Accordingly, the present invention may include any member not shown in the figures below. Further, within the scope of the present invention, each member shown in each of the following drawings may be changed or omitted.

FIG. 1 is a perspective view of a defoaming device 10 that constitutes a microbubble removing device according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof.

The defoaming device 10 includes a substantially rectangular parallelepiped housing 11 configured by combining a plurality of members. As shown in FIG. 2, a blood channel 12 having a circular cross section is formed in the housing 11 along the horizontal direction. The blood flow path 12 is defined by a seal portion 13 formed by using a seal material made of polyurethane resin, epoxy resin, or the like. A blood inlet port 15 and a blood outlet port 16 are provided on the rear wall and the front wall of the housing 11 corresponding to both ends of the blood flow path 12. The blood introducing port 15 and the blood deriving port 16 are arranged so as to open at the center of the circular cross section of the blood flow path 12. The blood B flows into the housing 11 through the blood introducing port 15, flows through the blood flow path 12, and flows out of the housing 11 through the blood drawing port 16.

A defoaming unit 20 is provided inside the housing 11. The defoaming unit 20 includes a hollow fiber membrane bundle 22 formed by stacking a large number (for example, 50 to 100 layers) of hollow fiber membranes 21. As the hollow fiber membrane 21, for example, a porous hollow fiber membrane made of polypropylene can be used. The hollow fiber membrane 21 is vertically oriented and arranged on the blood flow channel 12 so as to cross the blood flow channel 12, and both end portions thereof are held by the seal portions 13. The lower openings of the large number of hollow fiber membranes 21 are sealed by a seal portion 13, and the upper openings communicate with a decompression chamber 23 provided between the seal portion 13 and the housing 11. The decompression chamber 23 communicates with a deaeration port 25 provided on the upper wall of the housing 11. The degassing port 25 is connected to a pressure reducing means (for example, a vacuum pump, not shown).

The defoaming device 10 may be provided on the extracorporeal blood circulation circuit to form a cardiopulmonary system. The configuration of the extracorporeal blood circulation circuit in which the defoaming device 10 is incorporated is arbitrary and may be a known extracorporeal blood circulation circuit. One embodiment of a cardiopulmonary system includes a blood removal line connected to a patient's vein to remove blood from the patient, a blood reservoir for temporarily storing the blood removed through the blood removal line, and a blood reservoir in the blood reservoir. A blood pump for sending blood, an artificial lung for performing gas exchange with blood from the blood pump, a microbubble removing device of the present invention for removing microbubbles in blood that has passed through the artificial lung, and a vein of a patient. And a blood return line that returns blood to the patient that has passed through the microbubble removal device. The structures of the blood reservoir, the blood pump, and the artificial lung are not limited and may be known ones, for example. Preferably, the blood that has passed through the artificial lung flows into the blood introduction port 15 of the defoaming device 10, and the blood that has flowed out of the blood discharge port 16 returns to the patient through the blood return line. By incorporating the defoaming device 10 in the final stage of the cardiopulmonary system (that is, immediately before the blood return line), it is possible to reduce the microbubbles in the blood returned to the patient as much as possible. It is possible to effectively reduce the possibility of occurrence of.

As described above, blood that has passed through the oxygenator may contain microbubbles. Such blood passes through the gap between the hollow fiber membranes 21 forming the defoaming section 20. The inner cavity (reduced pressure space) of the hollow fiber membrane 21 is decompressed by the decompression means. The hollow fiber membrane 21 is provided with a large number of fine holes. Since the opening diameter of the micropores is very small (for example, 0.02 μm), blood cannot pass through the micropores due to its surface tension, but the gas that constitutes microbubbles in blood must pass through the micropores. You can Therefore, the gas in the blood flows into the inner cavity of the hollow fiber membrane 21 through the fine pores, passes through the decompression chamber 23 and the degassing port 25, and is discharged to the outside of the defoaming apparatus 10. In this way, microbubbles in blood can be removed. Further, the foreign matter in the blood can be captured and removed by the hollow fiber membrane 21.

Blood constituted a blood circuit in which the blood successively flows through the blood reservoir (reservoir) and the defoaming apparatus 10. Bovine blood prepared at Hb=12.0 to 12.5 g/dL and a temperature of 37.0 degrees was passed through this circuit at 5.0 L/min using a blood pump. Air was mixed into the blood at 500 mL/min on the upstream side of the blood reservoir. The blood mixed with air flowed into the blood reservoir, passed through the screen filter provided in the blood reservoir, and then flowed into the defoaming apparatus 10. The number of bubbles in the blood was measured by a bubble counter at two points, that is, on the upstream side of the defoaming apparatus 10 (that is, between the blood reservoir and the defoaming apparatus 10) and on the downstream side of the defoaming apparatus 10.

The defoaming apparatus 10 has a configuration shown in FIGS. 1 and 2, and has a hollow fiber membrane bundle 22 in which 100 layers of porous hollow fiber membranes (opening diameter of fine pores 0.02 μm) made of polypropylene are laminated. Was. The degassing port 25 was connected to a vacuum pump, the pressure in the decompression chamber 23 was decompressed into three ways of 0 kPa (no decompression), -68 kPa, and -100 kPa, and the number of bubbles in each case was measured.

The number of bubbles in the blood on the upstream side of the defoaming apparatus 10 was about 130, which was almost constant. On the other hand, the number of bubbles in the blood on the downstream side of the defoaming apparatus 10 was 50 to 60 when the pressure was not reduced, whereas when the pressure in the decompression chamber 23 was reduced to −68 kPa. Approximately 30 and approximately 10 when the decompression chamber 23 was decompressed to -100 kPa.

From this result, it was confirmed that air bubbles (micro bubbles) in blood can be removed by reducing the pressure on the side opposite to the blood side with respect to the hollow fiber membrane.

INDUSTRIAL APPLICABILITY The present invention has an excellent ability to remove microbubbles in blood, and thus can be used in an extracorporeal blood circuit having a line for returning blood to a patient. In particular, it can be preferably used for an extracorporeal blood circulation circuit used in heart surgery in which microbubbles are easily mixed in blood.

10 Defoaming Device 11 Housing 12 Blood Channel 21 Hollow Fiber Membrane 22 Hollow Fiber Membrane Bundle

Claims (4)

A housing provided with a blood channel, and a defoaming device provided with a hollow fiber membrane provided in the housing so as to come into contact with blood flowing through the blood channel,
A microbubble removing device comprising: a depressurizing means for depressurizing the lumen of the hollow fiber membrane,
The cross section of the blood channel is circular, the hollow fiber membrane is arranged to cross the blood channel ,
The microbubble removing device is configured to remove microbubbles flowing through the blood flow path together with blood by depressurizing the inner cavity of the hollow fiber membrane. apparatus. The microbubble removing device for blood according to claim 1, wherein one end of the hollow fiber membrane is sealed and the other end of the hollow fiber membrane is communicated with the decompression means. The device for removing microbubbles in blood according to claim 1 or 2, wherein the decompression unit decompresses the lumen so that the pressure difference between the inside and the outside of the hollow fiber membrane becomes 50 kPa or more. A blood removal line for removing blood from a patient, a blood reservoir for temporarily storing blood removed through the blood removal line, a blood pump for delivering blood in the blood reservoir, and a blood pump And a microbubble removing device according to any one of claims 1 to 3, which removes microbubbles in blood that has passed through the artificial lung, the artificial lung performing gas exchange with respect to the blood. A cardiopulmonary system comprising a blood return line for returning blood that has passed through the device to a patient.

Images