Patent Application
20110098626
The present invention relates to a blood reservoir that temporarily stores extracorporeally circulating blood in an extracorporeal circulation circuit for use in cardiopulmonary surgeries or the like. In particular, it relates to a blood reservoir equipped with a built-in cardiotomy section that filters intracardiac blood.
For cardiac surgeries or the like, an extracorporeal circulation circuit equipped with a blood pump or an artificial lung serving as a substitute for the function of a patient's heart or lung is used. Such an extracorporeal circulation circuit is provided with a blood reservoir (sometimes referred to as a “venous blood reservoir”) for temporarily storing venous blood removed from a patient's vein and adjusting the blood volume in a circulating circuit, and a blood reservoir (sometimes referred to as an “cardiotomy reservoir”) for aspirating, collecting, and temporarily storing blood (intracardiac blood) flowing out of the operative field. As compared to the venous blood, the intracardiac blood contains a high proportion of air bubbles or extraneous materials, such as pieces of flesh, fats, and clots, so the cardiotomy reservoir is provided with a cardiotomy section composed of a filter for removing extraneous materials and a defoamer for defoaming. Storing both of the venous blood and the intracardiac blood in a common blood reservoir is also widely practiced.
The intracardiac blood aspirated from the operative field by a pump flows into the cardiotomy section 900 through the conduit tube 935, and flows out of the cardiotomy section 900 after passing through the filter 910. In the cardiotomy section 900, air bubbles contained in blood float up to the blood surface. The air bubbles that have floated up to the blood surface gradually rise as they increase in number, but they are broken when they came in contact with the defoamer 920. In this way, the defoamer 920 restricts the growth of air bubbles on the blood surface so that the air bubbles do not rise above a certain level.
Patent Document 1 discloses that the lower end of the conduit tube 935 should be located at a higher level than the maximum blood surface level 950, and more preferably, at a higher level than the lower end of the defoamer 920, because the number of generated air bubbles will increase if the lower end of the conduit tube 935 becomes immersed in blood in the cardiotomy section.
The conventional cardiotomy section 900 illustrated in
It is thus an object of the present invention to solve the above-described conventional problems and to provide a blood reservoir equipped with a cardiotomy section having high defoaming performance.
A blood reservoir according to the present invention includes a housing that includes an intracardiac blood inflow port in an upper portion thereof and a blood outflow port at a lower end thereof a cardiotomy section arranged in the housing, and a conduit tube that communicates with the intracardiac blood inflow port and allows blood to flow out of the intracardiac blood inflow port into the cardiotomy section. The conduit tube is inserted from above downward in the cardiotomy section. The cardiotomy section includes a filter and a defoamer arranged inside the filter. A lower end of the filter is sealed or folded in an approximately straight line or in a curve. As viewed from above, the defoamer is arranged annularly along an inner peripheral surface of the filter.
A lower end of the conduit tube is located at the same level as or at a lower level than a lower end of the defoamer, with respect to a vertical direction.
In a projection view of a lower end face of the defoamer with respect to a horizontal plane, (Ru2−2×Tu)/(Ru1−2×Tu)≦0.24 is satisfied where Ru1 is an outer dimension of the annularly arranged defoamer in a major axial direction, Ru2 is an outer dimension thereof in a minor axial direction, and Tu is a thickness of the defoamer.
The present invention achieves a blood reservoir equipped with a cardiotomy section having high defoaming performance.
The housing body 31 includes a blood storage section 32 that is formed by a non-central part of the bottom protruding downward, and a blood outflow port 33 that is provided at the lower end of the blood storage section 32 and allows the outflow of blood. A fixing hole 34 is formed on the underside of the housing body 31 in order to hold the blood reservoir 5 by inserting therein an upper end of a support provided upright in an operating room.
The lid 36 has mounted thereon multiple intracardiac blood inflow ports 50 that allow the inflow of intracardiac blood, and a venous blood inflow port 51 that allows the inflow of venous blood. The lid 36 further is provided with multiple liquid medicine injection ports 71 and 72 for mixing a liquid medicine or the like in blood, a service port 73 for mixing a large volume of liquid medicine into blood in an urgent need or for allowing the inflow of blood that has passed through an alternate cardiotomy section in a case where the filter 10 of the cardiotomy section 2 cannot be used because of clogging, an evacuation port 74 for adjusting pressure in the blood reservoir 5, a pressure regulating valve 75 for preventing development of an abnormal positive or negative pressure in the blood reservoir 5, and so on. The venous blood inflow port 51 has a temperature probe 52 stuck therein for measuring the temperature of venous blood.
The venous blood inflow port 51 is connected to a blood removal line tube in an extracorporeal circulation circuit, and the intracardiac blood inflow ports 50 are connected to intracardiac blood aspiration line tubes. The blood outflow port 33 is connected to a blood sending line tube in the extracorporeal circulation circuit. The liquid medicine injection ports 71 and 72 are connected to liquid medicine injection line tubes connected to predetermined liquid medicine packs. A liquid medicine from the liquid medicine injection port 71 flows into the blood storage section 32 without passing through the cardiotomy section 2, whereas a liquid medicine from the liquid medicine injection port 72 flows into the blood storage section 32 after passing through the cardiotomy section 2. The service port 73 is connected to various line tubes. The temperature probe 52 is connected to electric wiring connected to temperature measuring equipment.
The housing 30 stores therein a support member 40 for holding a venous blood filter screen 47.
The venous blood filter screen 47 has no particular limitations on its configuration and material as long as it has the function of a filter for removing extraneous materials or air bubbles in blood, and any known material or the like may be selected and used as appropriate. For example, a screen filter having a large number of superfine openings may be used as the venous blood filter screen 47.
The venous blood inflow port 51 and the upper end of a venous blood inlet tube 80 are connected via the lid 36. The venous blood inlet tube 80 is fitted into the groove 43 of the cup section 41 and guided inside the support member 40 from the cup section 41 to the frame section 45, with a lower end opening thereof located at a lower level than a minimum blood surface level B in the blood reservoir 5.
Below the intracardiac blood inflow port 50, the cardiotomy section 2 is arranged in the support member 40. The cardiotomy section 2 includes the filter 10 having a bag-like shape as a whole (or a shape similar to a paper coffee filter used to extract coffee), a defoamer 20 arranged inside the filter 10, and a resin plate 60 bonded to the upper ends of the filter 10 and the defoamer 20. The resin plate 60 has a through hole 61 formed in about the center thereof. A conduit tube 90 is inserted from above in the through hole 61. The conduit tube 90 communicates with the multiple intracardiac blood inflow ports 50 and the multiple liquid medicine injection ports 72 provided on the lid 36. A lower end (folded part) 11a of the filter 10 is in contact with the bottom of the cup section 41, which reduces foaming of the blood flowing out of the cardiotomy section 2.
The flow of blood in the blood reservoir 5 is described below briefly. The venous blood removed from a patient's vein passes through the venous blood inflow port 51 and the venous blood inlet tube 80 in sequence, flows out of the lower end opening of the venous blood inlet tube 80, passes through the venous blood filter screen 47, and flows out of the blood outflow port 33. Meanwhile, the intracardiac blood aspirated from a patient's operative field passes through an intracardiac blood inflow port 50, the conduit tube 90, and the cardiotomy section 2 in sequence, flows into the support member 40, passes through the venous blood filter screen 47, and flows out of the blood outflow port 33. In the course of this process, blood is stored temporarily in the blood storage section 32.
A method for manufacturing such a filter 10 is described below.
First, as illustrated in
Then, as illustrated in
The filter member 11 then is folded in the direction indicated by the arrows 16a and 16b along a fold line 15 indicated by the chain double-dashed line parallel to the second direction 802 orthogonal to the first direction 801, the fold line 15 passing through an intermediate position of the filter member 11 in the first direction 801. At this time, the filter member 11 can be folded with ease and good appearance, for example if a straight-line edge of a jig made of a hard material such as resin or metal is pressed against the filter member 11 along the fold line 15, with all the mountains (ridges) of the pleats that are in contact with the jig being displaced toward either side of the second direction 802.
Then, both edges of the filter member 11 with respect to the second direction 802 are sealed and bonded together. Specifically, referring to an edge 11b on one side with respect to the second direction 802, an edge portion 11b1 on one side with respect to the fold line 15 and a short edge portion 11b2 on the other side are sealed overlapping each other. An edge 11c on the other side with respect to the second direction 802 is also sealed in a similar manner. The method of sealing is not particularly limited and may be selected as appropriate taking into consideration the material for the filter member 11 or the like, and for example, a heat seal method may be used. At this time, a material such as vinyl chloride that improves sealing properties may be inserted between the two sealed members (e.g., between the edge portions 11b1 and 11b2).
In this manner, the filter 10 having a bag-like shape as a whole (a shape similar to a paper coffee filter used to extract coffee), as illustrated in
The filter member 11 of the filter 10 has a three-layered laminate structure composed of the screen filter 12 and the pair of support members 13a and 13b that sandwich the screen filter 12. Because the screen filter 12 is held by being sandwiched between the pair of support members 13a and 13b having relatively high mechanical strength, the screen filter 12 can be maintained in a desired shape. In addition, since multiple pleats are formed in the filter member 11, the surface area of the filter member 11 increases, which improves the filtration efficiency and prolongs the life of the filter.
The screen filter 12 has the function of catching and removing extraneous materials in blood when the blood passes through. It further may have the function of catching air bubbles. There are no particular limitations on the screen filter 12 having such a function, and any known screen filter used in conventional cardiotomy sections may be selected and used arbitrarily. For example, a mesh filter composed of a resin material such as polyester, nylon, or polypropylene may be employed. The hole diameter of such a filter is not particularly limited, but is preferably from 20 μm to 50 μm inclusive.
The support members 13a and 13b are used to maintain the shape of the screen filter 12. They thus need to have higher mechanical strength than the screen filter 12. There are no particular limitations on the support members 13a and 13b, and any known support member used in a conventional cardiotomy section may be selected and used arbitrarily. For example, a mesh member composed of a material having good heat-sealing properties, such as polypropylene, may be employed. The hole diameter of the support members 13a and 13b is preferably larger than the hole diameter of the screen filter 12.
The screen filter 12 and/or the support members 13a and 13b may be coated with a defoaming agent (e.g., silicone) so that they have the function of defoaming.
In
The defoamer 20 is, as illustrated in
The cardiotomy section 2 according to Embodiment 1 of the present invention does not include the lower resin plate 932 of the conventional cardiotomy section 900 illustrated in
As illustrated in
Also, as illustrated in
The above-described condition A implies that the lower end of the defoamer 20 surrounds the conduit tube 90. In the above-described condition B, the ratio (Ru2−2×Tu)/(Ru1−2×Tu) represents the aspect ratio of a region that is surrounded by the ring-shaped defoamer 20 as viewed upward from a space (lower space) 17 located at a lower level than the lower end of the defoamer 20 in the filter 10 (see
If L is the vertical distance between the lower end of the conduit tube 90 and the lower end of the defoamer 20, it is preferable that L/Hu≦0.1 be satisfied. If the ratio L/Hu is higher than this upper limit, i.e., if the length L of downward protrusion of the conduit tube 90 from the lower end of the defoamer 20 is too long, the possibility that the lower end of the conduit tube 90 is immersed in the blood stored in the cardiotomy section 2 is increased, which increases the resistance to the inflow of blood into the cardiotomy section 2 through the conduit tube 90.
If Hf is the inner vertical dimension of the filter 10 (i.e., the vertical distance from the underside of the resin plate 60 to the lower end of the inner wall of the filter 10), it is preferable that 0.2≦Hu/Hf≦0.95, or more preferably 0.3≦Hu/Hf≦0.9, be satisfied. If the ratio Hu/Hf is higher than the upper limit expressed by this inequality, the length Lt of the conduit tube 90 needs to be increased in order to satisfy the above condition A. This consequently increases the possibility that the lower end of the conduit tube 90 is immersed in the blood stored in the cardiotomy section 2, thereby increasing the resistance to the inflow of blood into the cardiotomy section 2. On the contrary, if the ratio Hu/Hf is lower than the lower limit expressed by this inequality, the upper space 18 becomes small and the area of the defoamer 20 that surrounds the upper space 18 also becomes small accordingly. This deteriorates the defoaming property in the upper space 18, i.e., the property of breaking air bubbles that have grown up into the upper space 18 through the channel 19.
The material for the conduit tube 90 is not particularly limited, and it may be the same material as used for the conventional conduit tube 935, such as polycarbonate. Also, the dimensions of the conduit tube 90 are not particularly limited; however, the outer diameter thereof is preferably from 8 mm to 16 mm inclusive, the inner diameter thereof is preferably from 6 mm to 12 mm inclusive, and the thickness thereof is preferably from 1.0 mm to 2.0 mm inclusive.
Embodiment 2 according to the present invention differs from Embodiment 1 with respect to the filter that configures the cardiotomy section. Now, what is different from Embodiment 1 will be described.
Like the cardiotomy section 2 according to Embodiment 1, the cardiotomy section 102 includes the filter 110 having a bag-like shape as a whole (or a shape similar to a paper coffee filter used to extract coffee), a defoamer 20 arranged inside the filter 110, and a resin plate 60 bonded to the upper ends of the filter 110 and the defoamer 20. The resin plate 60 has a through hole 61 formed at about the center thereof. Like the cardiotomy section 2 according to Embodiment 1, the cardiotomy section 102 is mounted on a blood reservoir 5, with a conduit tube 90 inserted from above in the through hole 61 (see
The filter 110 is made of a filter member 111 that is pleated along a first direction 801 illustrated in
A method for manufacturing the filter 110 is described below.
First, as illustrated in
Then, as illustrated in
Then, as illustrated in
Then, one short side 111b and the other short side 111c of the first member 111 are sealed and bonded into a tubular shape as illustrated in
Then, the edge on the non-support portion 111f side or in the vicinity thereof is sealed in an approximately straight line as illustrated in
As a last step, the filter member 111 is turned inside out so that the support member located inside with respect to the screen filter 112 in the state of
In the above-described manufacturing method, multiple pleats are formed in the filter member material 111′ and thereafter parts of the support members 113a and 113b are removed so as to produce the filter member 111 having the support portion 111e and the non-support portion 111f however, the present invention is not limited thereto. Alternatively, the method may be such that parts of the support members 113a and 113b are removed so as to produce the filter member 111 having the support portion 111e and the non-support portion 111f and thereafter multiple pleats are formed in the filter member 111. As another alternative, in the step illustrated in
Still further, the filter member 111 may not have to be turned inside out after the formation of the sealing portion 111a.
In the cardiotomy section 2 illustrated in
On the other hand, in the cardiotomy section 103 illustrated in
In other respects, Embodiment 2 of the present invention is identical to Embodiment 1.
Embodiment 3 according to the present invention differs from Embodiment 1 with respect to the lower end of the conduit tube 90 and the configuration in the vicinity thereof. Now, only what is different from Embodiment 1 will be described.
Now, the effect achieved by the pair of slits 91 will be described.
As illustrated in
Moreover, the following effect also can be achieved if the conduit tube 90 communicates with not only the intracardiac blood inflow port 50 but also the liquid medicine injection port 72 as in the blood reservoir 5 described in Embodiment 1.
In the case where the lower end of the conduit tube 90 becomes immersed in the blood 100 as illustrated in
In addition, it is also possible to suppress a negative pressure from building up in the liquid medicine injection port 72 connected to the conduit tube 90 when blood flows from the intracardiac blood inflow port 50 into the cardiotomy section 2 through the conduit tube 90. This will be described with reference to
The length HS of the slits 91 formed in the conduit tube 90 (the distance from the lower end of the conduit tube 90 to the upper end of the slits 91; see
Also, the width Ws of the slits 91 formed in the conduit tube 90 (the circumferential dimension of the conduit tube 90; see
In the foregoing description, while the number of slits 91 formed in the conduit tube 90 is two, the present invention is not limited thereto and the number of slits may be one or more than two. In the case where multiple slits 91 are formed, the slits 91 may preferably be arranged at regular angular intervals with respect to the center axis of the conduit tube 90. For the provision of multiple slits 91, all the slits 91 do not necessarily have the same length Hs and the same width Ws and may have different lengths and widths.
Instead of forming the slits 91 in the side of the conduit tube 90, through holes 92 may be formed at positions on the side of the conduit tube 90 and in the vicinity of the lower end thereof as illustrated in
In the foregoing description, while the slits 91 or the through holes 92 are provided in the conduit tube 90 in the blood reservoir according to Embodiment 1, the slits 91 or the through hole 92 may be provided similarly in the conduit tube 90 in the blood reservoir according to Embodiment 2. In that case as well, the same effect as described above can be achieved.
The above-described Embodiments 1 to 3 are merely examples and the present invention is not limited thereto.
While the above-described Embodiments 1 to 3 employ the filter 10 or 110 in which the filter member 11 or 111 including the screen filter 12 or 112 is pleated and formed into a bag-like shape, a filter of the cardiotomy section is not limited thereto. For example, a filter in which a non-woven fabric is formed into a bag-like shape without pleating may be used.
While all the lower ends 11a and 111a of the above-described cardiotomy sections 2, 102, and 103 are formed in a straight line, the present invention is not limited thereto, and they may be formed in a curve, for example. The lower ends 11a and 111a may preferably be formed in conformity with the surface shape of the member in the blood reservoir (e.g., the bottom of the cup section 41 or the venous blood inlet tube 80) so that, when the cardiotomy section is mounted in the blood reservoir, the area of contact between the lower ends 11a, 111a and the member is as large as possible. Such an increase in the area of contact between the lower ends 11a, 111a and the member in the blood reservoir allows the blood from the cardiotomy section to flow over the lower end 11a or 111a and the member in contact therewith to reach the blood storage section 32, thus preventing the foaming of blood flowing out of the cardiotomy section.
In the above-described cardiotomy sections 2, 102, and 103, although the defoamer 20 is held by being bonded to the resin plate 60, the method for holding the defoamer 20 is not limited thereto. For example, the defoamer 20 may be held with a jig that is provided at the lower end of the defoamer 20 so as to prevent the defoamer 20 from moving down with respect to the filter 10 or 110.
The blood reservoir according to the present invention is not limited to an integral type of an cardiotomy reservoir and a venous blood reservoir, such as the above-described blood reservoir 5, that allow the inflow of both venous blood and intracardiac blood, it may be any other known blood reservoir. For example, it may be an cardiotomy reservoir that does not allow the inflow of venous blood.
A cardiotomy section that has the same structure as the cardiotomy section 2 described in Embodiment 1 was created as follows.
A mesh filter made of polyethylene terephthalate (PET) and having a hole diameter of 40 μm was used as the screen filter 12. A mesh made of polypropylene and having a hole diameter of 1 mm was used as the support members 13a and 13b. Adjacent mountain and valley portions of multiple pleats formed in the filter member 11 had an interval of 10 mm. The edge of the filter 10 on the side opposite from the folded part 11a and one edge of the defoamer 20 were immersed in a polyurethane adhesive that had been poured into a predetermined shaped mold, under which conditions the polyurethane adhesive was hardened so as to form the resin plate 60. The inner vertical dimension Hf of the filter 10 was set to 78 mm. For the defoamer 20, an open-cell polyurethane foam with the surface thereof coated with silicone oil was used. The thickness Tu of the defoamer 20 was set to 10 mm and the vertical dimension Hu thereof was set to 40 mm (see
The aspect ratio ((Ru2−2×Tu)/(Ru1−2×Tu)) of the region surrounded by the lower end of the defoamer 20 was varied by changing the outer dimension Ru2 (see
[Test Method]
Air-containing (or air bubble-containing) blood (fresh citrated bovine blood, at a temperature of 25° C.) was caused to flow into the cardiotomy section through the conduit tube 90. The flow rate of blood was varied in six cases, specifically 0.1, 0.2, 0.5, 1.0, 1.5, and 2.0 (×−3m3/min), and at each different flow rate of blood, the volume of air contained in blood was varied in four cases, specifically, 0, 0.1, 0.2, and 0.5 (×−3 m3/min).
[Evaluation Method]
a. Internal Pressure Increase
A change in pressure in the cardiotomy section during the inflow of blood was measured with the water column manometer. The pressure in the cardiotomy section has correlation with the defoaming properties of the cardiotomy section. If the defoaming properties of the cardiotomy section are poor and air bubbles grow up to the upper space 18 (see
b. Visual Observations on Condition of Air-Bubble Generation and Defoaming Condition Visual observations were made on the condition of air-bubble generation and the defoaming condition in the cardiotomy section during the inflow of blood.
c. Evaluation
With all factors considered, including the above-described increase in internal pressure and visual observation results, the defoaming properties were classified into three levels: “O” (Excellent), “Δ” (Ordinary), and “x” (Poor).
[Evaluation Result]
The evaluation results are shown in Table 1.
As shown in Table 1, if the aspect ratio of the lower end face of the defoamer 20 was higher than 0.24, the defoaming properties were poor. The defoaming properties were also poor if the ratio Lt/Hu of the length Lt of the conduit tube 90 with respect to the vertical dimension Hu of the defoamer 20 was lower than 1.0.
A cardiotomy section 2 having the same structure as that in Experiment 1 was created. In Experiment 2, the aspect ratio of the region surrounded by the lower end of the defoamer 20 was set constant at 0.18 and Lt/Hu was set constant at 1.0, whereas the vertical dimension Hu of the defoamer 20 and the length Lt of insertion of the conduit tube 90 in the cardiotomy section 2 were varied.
A test was conducted using the same method as in Experiment 1, and the same method as in Experiment 1 was used for evaluation. The evaluation results are shown in Table 2.
As shown in Table 2, when Hu/Hf is from 0.3 to 0.9 inclusive, good defoaming properties were obtained.
The above-described embodiments and examples merely are intended to clarify the technical contents of the present invention and the present invention should not be interpreted to be limited to those embodiments and examples. Various modifications are possible within the scope of the claims and the spirit of the present invention, and the present invention should be interpreted broadly.
The present invention is widely applicable to blood reservoirs that are provided in an extracorporeal circulation circuit used in cardiopulmonary surgeries or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-220211 | Aug 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/064922 | 8/21/2008 | WO | 00 | 2/24/2010 |
