JP4853715B2 - Blood filter device - Google Patents

Description

  The present invention relates to a blood filter device used for filtering foreign substances, thrombi and the like in an artificial cardiopulmonary circuit.

  In consideration of safety, a blood filter device such as an arterial filter is often incorporated into an artificial cardiopulmonary circuit used for cardiac surgery involving extracorporeal circulation. The performance required for such a blood filter device is that from the viewpoint of ensuring patient safety, the patient is exposed to minute foreign matter in the cardiopulmonary circuit, thrombus generated during the operation, or air mixed in or removed from the circuit. There is a strong demand for a structure that can be excluded from being sent to the body.

  In general, a blood filter device is configured by filling a housing with a filter made of a polyester filter material of about 20 to 40 μm. By using a blood flow path in the housing, dust, impurities, blood clots, and the like are eliminated when blood passes through the filter medium. For example, Patent Document 1 discloses a blood filter device as shown in FIGS. 5 and 6.

  FIG. 5 is a cross-sectional view of the blood filter device. The housing 1 is made of, for example, resin, and includes a head portion 2 that forms an upper structure, a filtration portion 3 that forms a central structure, and a bottom portion 4 that forms a lower structure. The shape of the cross section of the housing 1 is circular.

  An inflow port 5 is provided on the side surface of the head portion 2. An air discharge port 6 for discharging air such as bubbles is provided at the top of the head portion 2. The head portion 2 has a shape such that the inner diameter gradually decreases as it goes upward. As a result, bubbles gather and easily rise along the inner peripheral surface of the head portion 2. The cross section of the head portion 2 is circular, and the inflow port 5 is provided so that blood flows in the horizontal direction and along the inner wall of the head portion 2. The blood flowing in from the inflow port 5 flows downward and flows into the filtration unit 3.

  The filter part 3 forms a cylindrical shape, and a filter 8 for filtering foreign substances in the blood is disposed. The filter 8 is disposed so as to partition the lumen of the housing 1 into the head portion 2 side and the bottom portion 4 side. The bottom portion 4 is provided with an outflow port 7, and the liquid flowing into the head portion 2 from the inflow port 5 passes through the filtration portion 3 and flows out from the outflow port 7.

  As conceptually shown in FIG. 6, the filter 8 has a flat plate shape in which a sheet-like filter medium 8 a made of a sheet-like mesh is folded by forming a plurality of pleats, and ridge lines 8 b of the plurality of pleats are arranged in a planar shape. Have. That is, the envelope surfaces of the lower and upper ridgelines (tops) 8b of each pleat are flat. The filter 8 has a flat plate surface traversing the lumen of the holding portion inner cylinder 3b (filtering portion 3). Therefore, the ridge lines 8b of the plurality of pleats cross the lumen of the filtering portion 3 in parallel with each other. Has been placed.

  As shown in FIG. 5, the outer peripheral portion of the filter 8 is filled with a bonding resin 9, and the filter 8 is bonded to the inner peripheral surface of the filtration portion 3 with the bonding resin 9.

According to the configuration as described above, foreign substances and blood clots in the blood can be surely eliminated, and since there are no obstacles in the vertical direction of the filter 8, bubbles attached to the upper surface of the filter 8 during the priming operation It can be easily eliminated simply by giving a physical shock to the housing.
International Publication WO 2004/084974 Specification

Regarding the configuration and function of the blood filter device as described above, points that should be considered in practice are:
1) Small size,
2) Ensure sufficient membrane area, and 3) Less pressure loss.

  The small size is necessary for reducing the volume of the blood filter device and reducing the blood filling amount. Also, securing a sufficient membrane area is necessary to maintain a sufficient filtration capacity as long as possible. Furthermore, a small pressure loss is important for realizing a smooth extracorporeal circulation and suppressing hemolysis and the like.

  It is desirable to satisfy the above conditions in a well-balanced manner. However, in order to obtain a small and sufficient membrane area, it is necessary to reduce the pleat pitch of the filter. As a result, it becomes difficult to remove bubbles and increase the pressure loss. Therefore, it is attempted to reduce the pleat pitch of the filter within a range in which the ease of air bubble removal is secured and an increase in pressure loss can be sufficiently avoided.

  However, when the pleat pitch of the filter is set to a practically suitable range, it is difficult to visually recognize the presence of remaining bubbles, particularly in the outer peripheral portion of the filter, and it may be difficult to remove the bubbles depending on the situation. That is, an acute angle space is formed between the inner wall of the housing and the pleated slope of the filter, and when air bubbles are trapped in the acute angle space, the state is difficult to visually recognize from the outside even if the housing is transparent. . Moreover, in such an acute angle space, the force for capturing the bubbles is strong, and a large impact force is required to open the bubbles.

  Therefore, the present invention provides for the presence of air bubbles remaining on the outer periphery of the filter even in a structure in which a pleat pitch is reduced to secure a sufficient membrane area in a small-volume housing that suppresses blood filling. It is an object of the present invention to provide a blood filter device that can easily recognize the air bubbles and can easily remove bubbles.

  The blood filter device of the present invention is provided with an inflow port and a head part that forms an upper structure, a filtration part that forms a central part structure below the head part, and an outflow port that is disposed below the filtration part. A housing having a bottom portion, and a filter that is mounted in the lumen of the filtration portion and partitions the lumen of the housing into the head portion side and the bottom portion side. The filter is formed by folding a sheet-like filter medium to form a plurality of pleats, and the pleats of the plurality of pleats are arranged in parallel to each other so as to cross the lumen of the filtration unit, and from the inflow port, the filter The blood flowing into the head portion passes through the filter and flows out from the outflow port. In order to solve the above-mentioned problem, the filter has a flat portion in which a region corresponding to a peak portion that forms at least the uppermost ridge line or the valley portion that forms a lower ridge line of the pleat is formed flat.

  According to the above configuration, since the flat portion is formed on the outer peripheral portion of the filter, the distance between the inner surface of the housing and the slope of the pleats of the filter is sufficiently large. Therefore, the space on the flat portion formed between the inner surface of the housing and the slope of the pleats of the filter has a sufficient width, and the possibility that bubbles are trapped is low. Moreover, even if bubbles are trapped, they can be easily visually recognized due to the size of the space. Since the force captured by the bubbles is weak, the bubbles are easily opened by a small impact force.

  In the blood filter device of the present invention, the ratio P / H of the pitch P of the pleat and the height difference H between the upper ridge line and the lower ridge line of the pleat is 0.04 ≦ P / H ≦ 0.74. It is preferable that

  Moreover, it is preferable that the said filtration part has a cylindrical lumen | bore whose cross section in a horizontal direction is circular.

  Further, it is preferable that an air discharge port is provided at the top of the head portion.

  Hereinafter, a blood filter device according to an embodiment of the present invention will be described with reference to the drawings.

  1 is a front view of a blood filter device according to an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a sectional view thereof. The housing 1 is made of, for example, resin, and includes a head portion 2 that forms an upper structure, a filtration portion 3 that forms a central structure, and a bottom portion 4 that forms a lower structure. The shape of the cross section of the housing 1 is circular.

  An inflow port 5 is provided on the side surface of the head portion 2 so that blood flows in the horizontal direction and along the inner wall of the head portion 2. An air discharge port 6 for discharging air such as bubbles is provided at the top of the head portion 2. The bottom part 4 is provided with an outflow port 7. The filtration unit 3 forms a cylindrical shape. As shown in FIG. 3, the filter 3 is provided with a filter 8 for filtering foreign matter in the blood. The filter 8 divides the lumen of the housing 1 into the head portion 2 side and the bottom portion 4 side, and the liquid that flows into the head portion 2 from the inflow port 5 flows out of the outflow port 7 through the filtration portion 3. To do.

  The head portion 2 has a shape such that the inner diameter gradually decreases as it goes upward. As a result, bubbles gather and easily rise along the inner peripheral surface of the head portion 2. Further, the cross section of the head portion 2 is circular, and the inflow port 5 is provided so that blood flows in the horizontal direction and along the inner wall of the head portion 2. The blood flowing in from the inflow port 5 flows downward and flows into the filtration unit 3. The shape of the head portion 2 may be other than the shape shown in FIG. 1 or the like as long as the outer diameter gradually decreases toward the air discharge port 6. For example, a conical shape or a funnel shape can be used.

  As shown in FIG. 3, the housing 1 includes a housing upper half 1a and a housing lower half 1b. The filtration part 3 is comprised from the holding | maintenance part inner cylinder 3a and the holding | maintenance part outer cylinder 3b which were each formed in the housing upper half 1a and the housing lower half 1b. The housing 1 is integrated by fitting the housing upper half 1a and the housing lower half 1b in the holding portion inner cylinder 3a and the holding portion outer cylinder 3b. Further, the bonding resin 9 is filled in the region where the outer peripheral portion of the filter 8 is located in the filtering portion 3, that is, the holding portion inner cylinder 3 a. The filter 8 is bonded to the inner peripheral surface of the holding portion inner cylinder 3a by a bonding resin 9.

  As in the conventional example shown in FIG. 6, the filter 8 is a flat plate shape in which a sheet-like filter medium 8a made of a sheet-like mesh is folded by forming a plurality of pleats, and ridge lines 8b of the plurality of pleats are arranged in a plane. Have That is, the envelope surfaces of the lower and upper edge lines 8b of each pleat are flat. The filter 8 has a flat plate surface traversing the lumen of the holding portion inner cylinder 3b (filtering portion 3). Therefore, the ridge lines 8b of the plurality of pleats cross the lumen of the filtering portion 3 in parallel with each other. Has been placed. However, in the structure of FIG. 3, unlike the case of FIG. 5, the filter 8 is arranged so that the ridge line 8 b of each pleat is parallel to the direction of the inflow port 5 or the outflow port 7. By orienting the ridge line 8b of each pleat in this way, the removal of bubbles is facilitated by the blood or priming liquid flowing parallel to the pleat ridge line 8b.

  The bottom portion 4 has a conical portion that forms a conical surface whose inner bottom surface is convex downward. This conical surface is effective to reduce the pressure loss of the blood flow. In practice, the pressure loss is desirably 7.98 kPa or less, more preferably 6.65 kPa or less. By providing the conical portion, such a target value of pressure loss can be easily achieved.

  FIG. 4A is a plan view showing the filter device in a cross section of the filtration unit 3 of the housing 1, and shows a planar shape of the loaded filter 8. 4B is a cross-sectional view taken along line AA in FIG. 4A. However, in FIG. 4B, only the filtration part 3 is shown in a cut state. As conceptually shown in FIGS. 4A and 4B, the filter 8 has a shape in which a sheet-like filter medium 8a made of a sheet-like mesh is folded by forming a plurality of pleats. The pleat ridge line 8b in FIG. 4A is indicated by a thick solid line in the case of a peak and a thin solid line in the case of a valley.

  The ridge lines 8b of the plurality of pleats are arranged so as to cross the lumen of the holding portion inner cylinder 3a (filtering portion 3) in parallel with each other. That is, the plane (envelope surface) including the ridge line 8 b of each pleat is oriented in the chord direction of the holding portion inner cylinder 3 a so as to be parallel to the direction of the inflow port 5 or the outflow port 7. Therefore, FIG. 3 is a cross section in a plane parallel to the ridgeline 8b of the pleat, and the pleat is not shown.

  In FIG. 4A, the outermost peripheral ridge line position 10 indicated by a one-dot chain line on the outer peripheral portion of the filter 8 indicates a position corresponding to the ridge line 8b of the pleat in the outermost peripheral portion. That is, in the present embodiment, the ridge line 8b is not formed at the outermost peripheral ridge line position 10, and the flat portion 11 is formed as shown in FIG. 4B. The range corresponding to the flat portion 11 is selected from a portion corresponding to a peak or valley that forms at least the outermost ridge line 8b of the pleat. That is, at least one mountain or one valley is crushed to form the flat portion 11.

  By the form and arrangement of the filter 8 as described above, blood flowing into the head portion 2 and flowing downward passes through the filter 8 without leakage, and only the filtered blood flows into the bottom portion 4. Further, bubbles remaining when the filling liquid passes through the filter 8 during the priming operation can be easily formed by applying an impact in the vertical direction from the outside to the filter 8 by an operation such as repelling the bottom portion 4 with a finger. It is released from the filter medium 8 a and discharged from the air discharge port 6 above the head portion 2 or the outflow port 7 of the bottom portion 4. That is, since the air bubbles separated from the filter 8 are free from any obstacles in the vertical direction, the air bubbles reliably reach the air discharge port 6 or the outflow port 7 without being attached again to other parts of the filter 8 and are discharged.

  Further, in the filter device according to the present embodiment, since the flat portion 11 is formed on the outer peripheral portion of the filter 8, the distance between the inner surface of the housing 1 and the slope of the pleats of the filter 8 is sufficiently large. Therefore, the space on the flat portion 11 formed between the inner surface of the housing 1 and the slope of the pleats of the filter 8 has a sufficient width, and the possibility that bubbles are trapped is low. Moreover, even if bubbles are trapped, they can be easily visually recognized due to the size of the space. Since the force captured by the bubbles is weak, the bubbles are easily opened by a small impact force.

  In addition, if the number of the ridges 8b of the pleat made into the flat part 11 is one, the reduction | decrease of the film | membrane area of the sheet-like filter medium 8a by formation of the flat part 11 will be slight, and it has a practical influence on the filtration capability. There is nothing. If the influence on the filtering ability can be suppressed to a practically non-problematic range, the number of ridge lines 8b of the pleat as the flat portion 11 can be set to two or more.

  4B and the pleat height H, which is the difference in height between the upper ridge line and the lower ridge line of the pleat, has a ratio P / H of 0.04 ≦ P / H ≦ 0. .74 is desirable. If 0.04 ≦ P / H, the membrane area of the sheet-like filter medium 8a can be sufficiently secured. Further, if P / H ≦ 0.74, the sharp angle of the space formed between the inner surface of the housing 1 and the slope of the pleat due to the formation of the flat portion 11 is suppressed, and the captured bubbles are visually recognized. And it can facilitate the removal of bubbles.

  The practical values of the pleat pitch P and the pleat height H are set in consideration of the required film area and conditions that facilitate bubble removal. For example, the pitch P of the pleats is 1.6 to 3.7 mm, and the pleat height H is 5 to 30 mm. If the pitch P of the pleats is less than 1.6 mm, it is difficult to remove bubbles, and if it exceeds 3.7 mm, it is difficult to secure the filter membrane area. If the pleat height H is less than 5 mm, it is difficult to secure the filter membrane area. If the pleat height H exceeds 30 mm, the volume of the filtration unit 3 increases accordingly, which causes an increase in blood filling amount.

  In the present embodiment, as the sheet-like filter medium 8a, a mesh-like material, a woven fabric, a non-woven fabric, or a combination thereof can be used. As a material, polyester, PET (polyethylene terephthalate), polypropylene, polyamide, fluorine fiber, stainless steel, or the like can be used.

  The shape of the cross section of the housing 1, particularly the head portion 2, is preferably circular, but the same effect as described above can be obtained even if another shape such as an ellipse is used. Further, the shape of the head portion 2 in the vertical direction may be other than the shape shown in FIG. 3 as long as the outer diameter gradually decreases toward the air discharge port 6. For example, a conical shape or a funnel shape can be used.

  The range in which the bonding resin 9 is filled is adjusted with the lower end of the inner peripheral edge of the head portion 2 as a reference. That is, the inner peripheral surface of the bonding resin 9 is set to match the diameter of the lower end of the inner peripheral surface of the head portion 2 (and the diameter of the cylindrical portion 4b of the bottom portion 4). As a result, the flow path in the filter 8 defined by the bonding resin 9 is smoothly continuous with the lower end of the inner peripheral surface of the head portion 2 and the upper end of the cylindrical portion 4b of the bottom portion 4. can get.

  The blood filter device as described above can be manufactured as follows. First, the filter 8 is attached to the holding portion inner cylinder 3a forming the filtration portion 3 of the housing upper half 1a, and the outer peripheral edge portion of the filter 8 is joined to the holding portion inner cylinder 3a with the auxiliary bonding resin for temporary fixing. . At this time, it is desirable to ensure a sufficient interval between adjacent pleats of the filter 8. Next, the lower housing half 1b is combined with the upper housing half 1a in which the filter 8 is loaded.

  Next, the housing 1 in which the filter 8 is accommodated is placed in a rotating jig, and while rotating the rotating jig, the bonding resin 9 made of, for example, urethane resin is filled in the outer peripheral portion of the holding portion inner cylinder 3b, and further filled The formed bonding resin 9 is cured. In this manner, a structure in which the filter 8 is fixed to the inner wall of the filtration unit 3 by the bonding resin 9 can be easily manufactured.

  According to the blood filter device of the present invention, it is easy to visually recognize the presence of bubbles remaining on the outer peripheral portion of the filter, and it is possible to easily remove the bubbles, which is useful as a blood filter device disposed in an artificial heart-lung circuit. It is.

The front view of the blood filter apparatus in Embodiment 1 of this invention Top view of the blood filter device Cross section of the blood filter device The top view which showed the blood filter apparatus in the cross section of the filtration part of a housing AA sectional view in FIG. 4A It is sectional drawing of the blood filter apparatus of a prior art example. It is a perspective view of the filter which comprises the blood filter apparatus. DESCRIPTION OF SYMBOLS 1 Housing 1a Housing upper half 1b Housing lower half 2 Head part 3 Filtration part 3a Holding part inner cylinder 3b Holding part outer cylinder 4 Bottom part 4a Conical part 4b Cylindrical part 5 Inlet port 6 Outlet port 7 Outlet port 8 Filter 8a Sheet Filter medium 8b pleat ridge line 9 bonding resin 10 outermost peripheral ridge line position 1011 flat portion

Claims (4)

A housing having a head portion provided with an inflow port and forming an upper structure, a filtration portion forming a central structure below the head portion, and a bottom portion disposed at the lower portion of the filtration portion and provided with an outflow port;
A filter that is mounted in the lumen of the filtration part and partitions the lumen of the housing into the head part side and the bottom part side;
The filter is formed by folding a sheet-shaped filter medium to form a plurality of pleats, and arranged such that ridge lines of the plurality of pleats cross the lumen of the filtration unit in parallel with each other,
In the blood filter device in which blood flowing into the head portion from the inflow port passes through the filter and flows out from the outflow port,
The blood filter device according to claim 1, wherein the filter has a flat portion in which a region corresponding to a peak portion forming at least the uppermost ridge line of the outermost periphery or a valley portion forming the lower ridge line is formed flat.   The ratio P / H of the height difference H between the pleat pitch P and the upper ridge line and the lower ridge line of the pleat is 0.04 ≦ P / H ≦ 0.74. Blood filter device.   The blood filter device according to claim 1, wherein the filtration unit has a cylindrical lumen having a circular cross section in the horizontal direction.   The blood filter device according to claim 1, wherein an air discharge port is provided at a top portion of the head portion.

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