JP6674802B2 - Centrifugal blood pump - Google Patents

Description

  The present invention relates to a centrifugal blood pump that transports blood using centrifugal force.

  Conventionally, as this type of centrifugal blood pump, for example, a centrifugal blood pump disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-28156) is known. Patent Document 1 discloses a centrifugal blood type including a casing, an impeller rotatably housed in the casing, a rotating shaft serving as a rotating shaft of the impeller, and bearing portions rotatably supporting both ends of the rotating shaft. A pump is disclosed.

JP 2005-28156 A

  2. Description of the Related Art A conventional centrifugal blood pump as disclosed in Patent Literature 1 is used in a device for transporting a large amount of blood, such as a heart-lung machine. For example, the flow rate of a centrifugal blood pump required for a heart-lung machine is about 1 to 7 L / min.

  On the other hand, in the field of artificial dialysis, a roller pump is usually used as a pump for transporting blood. The roller pump is provided with a tube through which blood passes, and a rotatable roller for pressing the tube. The roller pump rotates the tube while intermittently closing the tube with the roller, and sends out the blood by pressing the tube. For example, the flow rate of the roller pump required for the artificial dialysis device is about 0.05 to 0.6 L / min.

  However, since this roller pump pumps out blood by squeezing the tube, it is said that the degree of hemolysis increases due to the force applied to the tube and the negative pressure generated when the closed tube returns to its original shape. I have. Hemolysis refers to a phenomenon in which the cell membrane of red blood cells in blood is damaged by various factors such as physical and chemical factors, and the contents (particularly, hemoglobin) elute out of blood cells. Because red blood cells that have lysed lose their original functions, excessive hemolysis may cause hemolytic anemia due to lack of red blood cells in the blood, and inflammation may occur due to the contents escaping outside the cells. May cause a burden on the patient. Further, it is necessary to periodically replace the tube, which is complicated.

  For this reason, the present inventors are considering using a centrifugal blood pump for an artificial dialysis device. The centrifugal blood pump pushes out blood using centrifugal force generated by rotation of an impeller, and does not send out blood by squeezing a tube. Therefore, the degree of hemolysis of the centrifugal blood pump is smaller than that of the roller pump. Also, the centrifugal blood pump has less pulsation than the roller pump, and the maximum pressure and the minimum pressure do not become excessive. Therefore, the burden on the patient can be reduced. Also, there is no need to replace tubes.

  However, even in the centrifugal blood pump, not only hemolysis is generated due to friction generated between the rotating shaft of the impeller and the bearing portion supporting the rotating shaft, but also a thrombus may be generated due to frictional heat. Therefore, in the conventional centrifugal blood pump, there is still room for improvement from the viewpoint of suppressing the occurrence of hemolysis and thrombus generated between the rotating shaft and the bearing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a centrifugal blood pump that can further suppress the occurrence of hemolysis and thrombus generated between a rotating shaft and a bearing portion in solving the above-mentioned problems.

In order to achieve the above object, a centrifugal blood pump according to the present invention includes a casing,
An impeller rotatably housed in the casing;
A rotation shaft serving as a rotation axis of the impeller,
Bearings for rotatably supporting both ends of the rotary shaft,
A centrifugal blood pump comprising:
Both ends of the rotating shaft are each formed in a hemispherical shape,
The bearing unit includes a concave portion for supporting any one end of the rotating shaft,
The recess has the same curvature as the curvature of the hemispherical portion at the end of the rotating shaft, and the inner surface of the recess is formed smaller than the outer surface of the hemispherical portion at the end of the rotating shaft. It is characterized by.

According to the centrifugal blood pump according to the present invention, Ru can be suppressed hemolysis and thrombus generation occurs between the rotating shaft and the bearing portion more.

It is a sectional view of a centrifugal blood pump concerning an embodiment of the present invention. It is a top view which shows the schematic structure of the centrifugal blood pump of FIG. FIG. 3 is a sectional view taken along line AA of FIG. 2. FIG. 2 is a plan view partially showing a schematic configuration of the centrifugal blood pump of FIG. 1. FIG. 5 is a sectional view taken along line BB of FIG. 4. It is a side view which shows schematic structure of the centrifugal blood pump of FIG. FIG. 7 is a sectional view taken along line CC of FIG. 6. 9 is a graph showing the results of a hemolysis evaluation test on a plurality of pumps according to the present example and a gyro pump according to a comparative example, which were created by changing the contact angle between the rotating shaft and the bearing, and the diameter of the impeller. It is explanatory drawing which shows the state in which the contact angle of a rotating shaft and a bearing part is 30 degrees. It is explanatory drawing which shows the state in which the contact angle of a rotating shaft and a bearing part is 45 degrees. It is explanatory drawing which shows the state in which the contact angle of a rotating shaft and a bearing part is 60 degrees.

According to a first aspect of the present invention, a casing;
An impeller rotatably housed in the casing;
A rotation shaft serving as a rotation axis of the impeller,
Bearings for rotatably supporting both ends of the rotary shaft,
A centrifugal blood pump comprising:
Both ends of the rotating shaft are each formed in a hemispherical shape,
The bearing unit includes a concave portion for supporting any one end of the rotating shaft,
The recess has the same curvature as the curvature of the hemispherical portion at the end of the rotating shaft, and the inner surface of the recess is formed smaller than the outer surface of the hemispherical portion at the end of the rotating shaft. A centrifugal blood pump is provided.

  According to a second aspect of the present invention, there is provided the centrifugal blood pump according to the first aspect, wherein a depth of the concave portion is shorter than a radius of a hemispherical portion at an end of the rotary shaft corresponding to the concave portion. I do.

  According to the third aspect of the present invention, the angle formed between the rotation axis and the straight line passing through the outer peripheral edge of the contact surface between the hemispherical portion and the concave portion and the center of the hemispherical portion is 60 ° or less. , A centrifugal blood pump according to the first or second aspect.

  According to a fourth aspect of the present invention, there is provided the centrifugal blood pump according to the third aspect, wherein the angle is 45 ° or less.

  According to a fifth aspect of the present invention, there is provided the centrifugal blood pump according to the third aspect, wherein the angle is not less than 25 ° and not more than 35 °.

  According to the first to fifth aspects, since the contact area between the rotating shaft and the bearing is reduced, the frictional force between the rotating shaft and the bearing is reduced, and the occurrence of hemolysis and thrombus can be suppressed. it can.

  According to a sixth aspect of the present invention, there is provided the centrifugal blood pump according to any one of the first to fifth aspects, wherein the impeller is a closed impeller in which a flow path through which blood passes is provided. .

  According to the sixth aspect, since the impeller is a closed impeller provided with a flow path through which blood passes, the bearing load applied to the impeller can be reduced, and the priming volume in the casing is reduced. be able to.

  According to a seventh aspect of the present invention, there is provided the centrifugal blood pump according to the sixth aspect, wherein the flow path is provided to extend on a plane orthogonal to the rotation axis.

  According to the seventh aspect, since the flow path is provided so as to extend on a plane orthogonal to the rotation axis, the direction in which blood separates from the rotation axis on a plane orthogonal to the rotation axis. And impulse is exerted on the impeller in the vertical direction. Thus, the frictional force between the rotating shaft and the bearing can be reduced, so that the occurrence of hemolysis and thrombus can be suppressed.

According to an eighth aspect of the present invention, a driven magnet built in the impeller,
A driving magnet disposed outside the casing and magnetically coupled to the driven magnet;
A rotation device that rotates the drive-side magnet about the rotation axis,
With
The centrifugal blood pump according to any one of the first to seventh aspects, wherein the driven magnet and the driving magnet are provided on a plane orthogonal to the rotation axis.

  According to the eighth aspect, since the driven-side magnet and the drive-side magnet are provided on a plane orthogonal to the rotation axis, it is possible to suppress a vertical force from being applied to the impeller. it can. Thus, the frictional force between the rotating shaft and the bearing can be reduced, so that the occurrence of hemolysis and thrombus can be suppressed.

  According to a ninth aspect of the present invention, there is provided the centrifugal blood pump according to any one of the first to eighth aspects, wherein the centrifugal blood pump is a centrifugal blood pump for artificial dialysis.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< Embodiment >>
An overall configuration of a centrifugal blood pump according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a centrifugal blood pump according to an embodiment of the present invention. FIG. 2 is a plan view showing a schematic configuration of the centrifugal blood pump of FIG. FIG. 3 is a sectional view taken along line AA of FIG. FIG. 4 is a plan view partially showing the schematic configuration of the centrifugal blood pump of FIG. FIG. 5 is a sectional view taken along line BB of FIG. FIG. 6 is a side view showing a schematic configuration of the centrifugal blood pump of FIG. FIG. 7 is a sectional view taken along line CC of FIG.

  The centrifugal blood pump 1 according to the present embodiment is a centrifugal blood pump for artificial dialysis. As shown in FIG. 1, the centrifugal blood pump 1 includes a hollow casing 2, an impeller 3 rotatably housed in the casing 2, a rotating shaft 4 serving as a rotating axis X of the impeller 3, and a rotating shaft 4. And a bearing portion 5 for rotatably supporting both ends of the bearing.

  The casing 2 includes an upper casing 21 and a lower casing 22. The upper casing 21 and the lower casing 22 are combined and connected by a fastening member (not shown) such as a screw, so that a space S serving as a pump chamber is formed between the upper casing 21 and the lower casing 22. Is done.

  The casing 2 is provided with an inflow port 23 for flowing blood into the space S and an outflow port 24 for flowing blood from the space S, as shown in FIGS. 2, 4, and 6. I have.

  1 and 5, the inflow port 23 is provided so as to be inclined at a predetermined angle of less than 90 ° with respect to the rotation axis X. The inflow port 23 is in fluid communication with the space S at the inflow port 23a. As shown in FIGS. 4 and 5, the inflow port 23a is provided at a position offset from the rotary shaft 4 so that blood flowing in the inflow port 23 flows smoothly into a through hole 32 described later. With such a configuration, blood flowing in the inflow port 23 is appropriately supplied into the space S.

  The outflow port 24 is provided in a direction orthogonal to the rotation axis X and inclined with respect to the outer peripheral side surface of the casing 2 as shown in FIGS. Outflow port 24 is in fluid communication with space S at outlet 24a.

  The impeller 3 is rotatably housed in the space S. In this embodiment, the impeller 3 is a closed impeller in which a flow path 31 through which blood passes is provided as shown in FIGS. 4 and 5. The impeller 3 is provided with a through hole 32 penetrating in the direction in which the rotation axis X extends. The inflow port 23 a of the inflow port 23 and one end of each of the two flow paths 31, 31 are in fluid communication with the through hole 32. Although not shown, the impeller 3 and the rotating shaft 4 are connected by two to four connecting members.

  The two flow paths 31, 31 are provided so as to extend on a plane orthogonal to the rotation axis X. In the present embodiment, the two flow paths 31, 31 are formed as flow paths extending linearly from near the rotation axis X to near the outer peripheral side surface of the casing 2. The two flow paths 31, 31 are formed point-symmetrically about the rotation axis X in plan view.

  As shown in FIG. 1, the impeller 3 has a driven magnet 33 incorporated therein. The driven magnet 33 is provided so as to be magnetically coupled to a driving magnet 61 provided outside the casing 2. The drive-side magnet 61 is attached to a rotating device 62 that rotates the drive-side magnet 61 about the rotation axis X. When the rotating device 62 rotates the drive-side magnet 61 about the rotation axis X, the driven-side magnet 33 magnetically coupled to the drive-side magnet 61 rotates, and the impeller 3 containing the driven-side magnet 33 also rotates. Rotate.

  The driven magnet 33 and the driving magnet 61 are provided on a plane orthogonal to the rotation axis X. That is, the straight line L1 connecting the center of the driven magnet 33 and the center of the driving magnet 61 is configured to be orthogonal to the rotation axis X. With this configuration, it is possible to suppress the vertical force applied to the impeller 3 while magnetically coupling the driven magnet 33 and the driving magnet 61. Therefore, the frictional force between the rotating shaft and the bearing can be reduced.

  In the present embodiment, a plurality of (for example, six) driven magnets 33 are provided at a lower portion of the outer periphery of the impeller 3. The plurality of driven magnets 33 are provided at equal intervals in plan view, as shown in FIG. A plurality of (for example, six) driving magnets 61 are provided at positions corresponding to the driven magnets 33.

  Between the casing 2 and the impeller 3, when the impeller 3 rotates about the rotation axis X, the blood flowing in the direction away from the through-hole 32 and the blood discharged from the flow paths 31, 31 flows into the through-hole 32. A gap CL is provided to return. More specifically, the gap CL is such that the blood discharged from the flow paths 31 and 31 descends or rises along the side surface of the casing 2 and approaches the rotation axis X along the bottom surface or the top surface of the casing 2. And returns to the inside of the through-hole 32. Thereby, the blood in the casing 2 is circulated without staying at any place in the casing 2, so that a relatively thrombus such as a contact portion between the rotating shaft 4 and the bearing 5 is generated. This can be suppressed even in an easy place. Further, the pressure difference between the upper part of the impeller 3 where blood is sucked and the lower part of the impeller 3 where blood stays can be reduced, so that the vertical force applied to the impeller 3 can be suppressed. In the present embodiment, the width of the gap CL is formed substantially uniformly. The width of the gap CL is, for example, 0.5 mm.

  The rotation shaft 4 is arranged coaxially with the rotation axis X in the through hole 32 of the impeller 3. Although not shown, a part of the rotating shaft 4 is connected to the impeller 3. As a result, the impeller 3 rotates as the rotating shaft 4 rotates about the rotation axis X.

  The rotating shaft 4 is a substantially cylindrical shaft. As shown in FIGS. 1 and 3, both ends of the rotating shaft 4 are each formed in a hemispherical shape. That is, the upper end 41 and the lower end 42 of the rotating shaft 4 are each formed in a hemispherical shape. In the present embodiment, the rotary shaft 4 is formed symmetrically in the vertical and horizontal directions. The rotating shaft 4 is made of stainless steel (for example, SUS304).

As shown in FIG. 1, the bearing 5 includes an upper bearing 51 that rotatably supports the upper end 41 of the rotating shaft 4 and a lower bearing 52 that rotatably supports the lower end 42 of the rotating shaft 4. Have. That is, the centrifugal blood pump 1 is a double pivot type blood pump that rotatably supports both ends of the rotary shaft 4. The upper bearing portion 51 and the lower bearing portion 52 are made of, for example, ultra-high molecular weight polyethylene (UHMWPE).

  The upper bearing portion 51 has the same curvature as the curvature of the hemispherical portion of the upper end portion 41 of the rotating shaft 4, and includes a concave portion 51a whose inner surface is smaller than the outer surface of the hemispherical portion. Similarly, the lower bearing portion 52 has the same curvature as the curvature of the hemispherical portion of the lower end portion 42 of the rotary shaft 4 and includes a concave portion 52a whose inner surface is smaller than the outer surface of the hemispherical portion. Here, the “recess having the same curvature as the curvature of the hemispherical portion” includes a recess having substantially the same curvature in consideration of the curvature of the hemispherical portion, dimensional error, and the like. The concave portion only needs to support the hemispherical portion so as to be rotatable with substantially no gap. Further, “outer surface” and “inner surface” mean an exposed area.

  The blood that has flowed into the space S from the inflow port 23 a of the inflow port 23 flows into the through hole 32 of the impeller 3. When the impeller 3 rotates about the rotation axis X about the rotation shaft 4 by the rotation device 62, the blood flowing into the through hole 32 flows to the outer peripheral side surface of the casing 2 through the flow path 31 due to the centrifugal force of the impeller 3. At this time, since the contact area between the outer surface of the hemispherical portion of each end portion 41, 42 of the rotating shaft 4 and the inner surface of the concave portion 51a, 52a of the bearing portion 5 is small, blood is generated by the frictional force of the contact portion. Hemolysis can be suppressed.

  Most of the blood flowing to the outer peripheral side surface of the casing 2 enters the outflow port 24 through the outflow port 24a, and flows out of the centrifugal blood pump 1. On the other hand, a part of the blood flowing to the outer peripheral side surface of the casing 2 returns into the through hole 32 through the gap CL. That is, the blood in the casing 2 circulates without locally staying. Accordingly, even if heat is generated due to friction between the respective end portions 41 and 42 of the rotating shaft 4 and the concave portions 51a and 52a of the bearing portion 5, the temperature rise can be suppressed by circulating blood, and the thrombus is caused by the heat generation. The occurrence can be suppressed. Further, since the contact area between the outer surface of the hemispherical portion of each end 41, 42 of the rotating shaft 4 and the inner surface of the concave portion 51a, 52a of the bearing 5 is small, the heat generation itself can be suppressed.

  According to the present embodiment, the concave portions 51 a and 52 a of the bearing 5 have the same or substantially the same curvature as the curvature of the hemispherical portion of each end 41 and 42 of the rotary shaft 4. Thereby, the bearing part 5 can firmly support both ends of the rotary shaft 4.

  Further, according to the present embodiment, the inner surfaces of the concave portions 51 a and 52 a of the bearing portion 5 are formed smaller than the outer surfaces of the hemispherical portions of the respective end portions 41 and 42 of the rotary shaft 4. According to this configuration, hemolysis that occurs between the rotating shaft 4 and the bearing portion 5 can be further suppressed. Further, heat generation between the rotating shaft 4 and the bearing portion 5 can be suppressed, and the occurrence of thrombus can be suppressed.

  Further, according to the present embodiment, as the impeller 3, a closed impeller in which a flow path 31 through which blood passes is provided. According to this configuration, the bearing load applied to the impeller 3 can be reduced, the amount of blood in the casing 2 can be suppressed, and the priming volume can be reduced.

  Further, according to the present embodiment, the flow channel 31 is provided to extend on a plane orthogonal to the rotation axis X. The driven magnet 33 and the driving magnet 61 are provided on a plane orthogonal to the rotation axis X. According to these configurations, it is possible to suppress a vertical force applied to the impeller 3. Thereby, the force in the vertical direction (extending direction of the rotation axis X) applied between the rotating shaft 4 and the bearing portion 5 is suppressed, and the hemolysis can be further suppressed. Further, the thickness of the centrifugal blood pump 1 in the vertical direction can be suppressed, and the size of the centrifugal blood pump itself can be reduced.

  The flow rate of the pump required for the artificial dialysis device is, for example, about 300 to 600 mL / min, which is considerably lower than the flow rate of the pump required for the heart-lung machine. Therefore, when a conventional centrifugal blood pump is used for an artificial dialysis device, it is necessary to reduce the flow rate of the pump. Since centrifugal blood pumps use centrifugal force to push out blood, it is conceivable to lower the flow rate of the centrifugal blood pump by lowering the rotation speed of the pump. A stagnant portion of blood is formed in the inside, which causes thrombus formation. For this reason, a conventional centrifugal blood pump for cardiopulmonary bypass cannot be used. Other than the method of reducing the rotation speed of the pump, it is conceivable to reduce the diameter of the casing and the impeller, that is, to reduce the size of the centrifugal blood pump.

  However, if the size of the conventional centrifugal blood pump is reduced while maintaining its configuration, hemolysis and thrombus generation caused by the frictional force between the rotating shaft and the bearing become a nonnegligible level.

  In contrast, according to the present embodiment, the concave portions 51a and 52a of the bearing portion 5 have the same or substantially the same curvature as the curvature of the hemispherical portion of each end portion 41 and 42 of the rotary shaft 4. Even if the centrifugal pump 1 is downsized for use in artificial dialysis, the bearing 5 can firmly support both ends of the rotary shaft 4. In addition, since the inner surfaces of the concave portions 51 a and 52 a of the bearing portion 5 are formed smaller than the outer surfaces of the hemispherical portions of the respective end portions 41 and 42 of the rotating shaft 4, the gap between the rotating shaft 4 and the bearing portion 5 is reduced. Can reduce the frictional force generated in. As a result, even if the centrifugal pump 1 is downsized for use in artificial dialysis, it is possible to suppress the occurrence of hemolysis and thrombus to a negligible level.

  Next, a preferred contact angle between the rotating shaft 4 and the bearing 5 will be described.

  FIG. 8 shows a plurality of pumps (shown as NY1 to NY4) according to the present embodiment created by changing the contact angle between the rotating shaft 4 and the bearing portion 5 and the diameter of the impeller 3, and a gyro pump according to a comparative example ( Gyro) (shown as Gyro).

  9 to 11 are diagrams showing the contact angle between the rotating shaft 4 and the bearing 5. In the present embodiment, the upper end 41 and the lower end 42 of the rotary shaft 4 and the recesses 51a and 52a of the bearing 5 have the same shape and size. Therefore, FIGS. 9 to 11 show the positional relationship between the lower end portion 42 of the rotating shaft 4 and the concave portion 52 a of the lower bearing portion 51 as a representative example.

  As described above, the lower bearing portion 52 has the same or substantially the same curvature as the curvature of the hemispherical portion of the lower end portion 42 of the rotating shaft 4 and the concave portion 52a whose inner surface is smaller than the outer surface of the hemispherical portion. Have. That is, as shown in FIGS. 9 to 11, the depths D1 to D3 of the concave portions 52a are set shorter than the radius r of the hemispherical portion of the lower end portion 42 of the rotary shaft 4.

  In the NY1 pump, an angle θ formed by a rotation axis X and a straight line L2 passing through the outer peripheral edge E of the contact surface between the hemispherical portion of the lower end portion 42 of the rotary shaft 4 and the concave portion 52a and the center P of the hemispherical portion. Is set to 30 °. Here, the angle θ is simply referred to as a contact angle θ. In the NY2 pump, the contact angle θ is set to 45 °. In the NY3 pump, the contact angle θ is set to 60 °. In the NY1 to NY3 pumps, the diameter of the impeller 3 is set to 30 mm. FIG. 8 shows a hemolysis evaluation test for these NY1 to NY3 pumps at an impeller 3 rotation speed of 2,000 rpm and a pump flow rate of 50 mL / min, and a generalized hemolysis index obtained by the hemolysis evaluation test. (NIH (g / 20 min)) is shown.

  The gyro pump is a general centrifugal blood pump used in a heart-lung machine. In FIG. 8, a hemolysis evaluation test is performed on the gyro pump with the impeller 3 rotating at 2,090 rpm and a pump flow rate of 5 L / min, and the generalized hemolysis index (NIH (NIH ( g / 20 min)).

  As a calculation formula of the standardized hemolysis index NIH, a calculation formula of the ASTM standard is generally known. The calculation formula of the ASTM standard is to calculate the hemolysis index NIH (g / 100L) of 100L of blood with the pump flow rate being 5L / min. However, the pump flow rates of the NY1, NY2, and NY3 pumps according to the present embodiment are all 50 mL / min, and the calculation formula of the ASTM standard cannot be directly applied. On the other hand, the time for evaluating the hemolysis of 100 L of blood at a pump flow rate of 5 L / min is 20 minutes. For this reason, the calculation formula of the ASTM standard was modified, and the generalized hemolysis index (NIH (g / 20 min)) of each pump was obtained by the following calculation formula with an evaluation time of 20 minutes.

[Equation 1]
NIH (g / 20 min) = ΔfreeHb × V × (100−Ht) / 100 × (20 / T)

  In the above formula, ΔfreeHb indicates the difference (mg / L) in the plasma free hemoglobin concentration in the sampling time interval. V indicates the flow rate (L) in the circuit. Ht indicates a hematocrit value (%). T indicates a sampling time interval (min).

  As can be seen from FIG. 8, the generalized hemolysis index of the NY1 pump is about 0.0061, the generalized hemolysis index of the N2 pump is about 0.0093, and the generalized hemolysis index of the NY3 pump is about 0.0114. there were. The generalized hemolysis index of the gyro pump was about 0.0248. This shows that the NY1, pump NY2, and NY3 pumps according to the present embodiment can significantly reduce hemolysis as compared with the conventional gyro pump.

  The NY2 pump has a lower generalized hemolytic index than the NY3 pump, and the NY1 pump has a lower generalized hemolytic index than the NY2 pump. This indicates that the smaller the contact angle θ, the more the hemolysis can be suppressed. That is, it is understood that the contact angle θ is preferably equal to or less than 60 °, more preferably equal to or less than 45 °, and further preferably equal to 30 °. On the other hand, if the contact angle θ is too small, the bearing 5 cannot sufficiently support the rotating shaft 4, and the rotating shaft 4 may run out of shaft. Therefore, it is considered preferable that the contact angle θ is set to about 30 ° ± 5 °, that is, about 25 ° to 35 °.

  On the other hand, in the NY4 pump shown in FIG. 8, the contact angle θ is set to 60 ° which is the same as that of the NY3 pump, and the diameter of the impeller 3 is set to 34 mm which is larger than that of the NY3 pump. By increasing the diameter of the impeller 3, the pump flow rate can be improved. Therefore, when the pump flow rate is the same, the rotation speed of the impeller 3 can be reduced. For this reason, in FIG. 8, a hemolysis evaluation test was performed with respect to NY4 at an impeller 3 rotation speed of 1,760 rpm and a pump flow rate of 50 mL / min, and the generalized hemolysis index (NIH) obtained by the hemolysis evaluation test was used. (G / 20 min)).

  As can be seen from FIG. 8, the generalized hemolysis index of the NY4 pump was about 0.0085. This indicates that the NY4 pump according to the present embodiment can suppress the hemolysis more than the NY3 pump. That is, it is understood that hemolysis can be further suppressed by increasing the diameter of the impeller and reducing the rotation speed of the impeller.

  Note that the present invention is not limited to the above embodiment, and can be implemented in various other modes. For example, in the above description, the shape of the flow path 31 of the impeller 3 is linear, but the present invention is not limited to this. The flow path 31 of the impeller 3 may have another shape such as an arc shape.

  In the above description, the impeller 3 includes the two flow paths 31, 31, but the present invention is not limited to this. The impeller 3 may include one or three or more flow paths 31. In this case, it is preferable that the flow paths 31 be arranged in a well-balanced manner so as not to impair the rotational balance of the impeller 3. For example, when the impeller 3 includes three flow paths 31, the flow paths 31 are preferably arranged at equal intervals. It should be noted that, as in the above-described embodiment, when the number of the flow paths 31 of the impeller 3 is two, the manufacture is easy and the rotation balance of the impeller 3 is easy to keep.

  INDUSTRIAL APPLICABILITY The centrifugal blood pump according to the present invention can further suppress the occurrence of hemolysis and thrombus generated between the rotating shaft and the bearing portion, and thus is useful as a pump used not only in an artificial dialysis device but also in an artificial heart-lung machine and the like. It is.

DESCRIPTION OF SYMBOLS 1 Centrifugal blood pump 2 Casing 3 Impeller 4 Rotating shaft 5 Bearing part 21 Upper casing 22 Lower casing 23 Inflow port 23a Inflow port 24 Outflow port 24a Outflow port 31 Flow path 32 Through hole 33 Follower magnet 41 Upper end section 42 Lower end section 51 Upper bearing 51a recess 52 Lower bearing 52a recess 61 drive-side magnet 62 rotating device

Claims (9)

A casing,
An impeller rotatably housed in the casing;
A rotation shaft serving as a rotation axis of the impeller,
Bearings for rotatably supporting both ends of the rotary shaft,
A centrifugal blood pump used at a flow rate of 0.05 to 0.6 L / min ,
Both ends of the rotating shaft are each formed in a hemispherical shape,
The bearing unit includes a concave portion for supporting any one end of the rotating shaft,
The recess has the same curvature as the curvature of the hemispherical portion at the end of the rotating shaft, and the inner surface of the recess is formed smaller than the outer surface of the hemispherical portion at the end of the rotating shaft. Centrifugal blood pump.   The centrifugal blood pump according to claim 1, wherein a depth of the concave portion is shorter than a radius of a hemispherical portion at an end of the rotary shaft corresponding to the concave portion.   3. The centrifuge according to claim 1, wherein an angle formed by a straight line passing through an outer peripheral edge of a contact surface between the hemispherical portion and the concave portion and a center of the hemispherical portion and the rotation axis is 60 ° or less. 4. Type blood pump.   The centrifugal blood pump according to claim 3, wherein the angle is 45 ° or less.   The centrifugal blood pump according to claim 3, wherein the angle is not less than 25 ° and not more than 35 °.   The centrifugal blood pump according to any one of claims 1 to 5, wherein the impeller is a closed impeller provided with a flow path through which blood passes.   The centrifugal blood pump according to claim 6, wherein the flow path is provided so as to extend on a plane orthogonal to the rotation axis. A driven magnet built into the impeller,
A driving magnet disposed outside the casing and magnetically coupled to the driven magnet;
A rotation device that rotates the drive-side magnet about the rotation axis,
With
The centrifugal blood pump according to any one of claims 1 to 7, wherein the driven magnet and the driving magnet are provided on a plane orthogonal to the rotation axis.   The centrifugal blood pump according to any one of claims 1 to 8, wherein the centrifugal blood pump is a centrifugal blood pump for artificial dialysis.

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