JPH04212370A - Blood pump - Google Patents

Abstract

PURPOSE:To provide a blood pump which is small in size, is light in weight, is easy to be produced, lessens the generation of hemolysis, has good discharge efficiency and is usable safely over a long period of time. CONSTITUTION:A pedestal 5 formed to a circular conical shape having a base of a circular shape of 50 to 55mm in diameter is housed in a housing 1 and plural vanes 6 are formed of straight plates each having 20 to 50 deg. inlet angle on the circular conical surface of this pedestal 5. The pump is so formed that the ratio (L/H) between the length L along the curved surface of the vanes 6 and the height H parallel with the revolving shaft of a vane wheel at the front end of the radial direction of the vanes 6 disposed radially is 2.5 to 6.0.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a centrifugal blood pump, and more specifically, it is small, lightweight, easy to manufacture, has little hemolysis, and has good discharge efficiency.
This invention relates to a blood pump that can be used safely for a long period of time.

0002

[Prior Art and Problems to be Solved by the Invention] In recent years, centrifugal pump type blood pumps have become popular as blood pumps for extracorporeal circulation circuits such as heart-lung machines and cardiac auxiliary circulation devices after open-heart surgery. .

[0003] A centrifugal pump type blood pump is a blood pump that rotates an impeller in a pump chamber that has an inlet and an outlet port, and supplies a smooth flow according to the rotation speed of the impeller and the differential pressure across the pump. It is about.

[0004] This centrifugal blood pump does not require an expensive artificial valve or a synchronization device unlike pulsating blood pumps, so it can be made smaller, lighter, and lower in cost. Furthermore, unlike roller pump type blood pumps, the tubes do not break and can withstand continuous operation for long periods of time.

As conventional centrifugal pump type blood pumps, those shown in FIGS. 6 and 7 are mainly known.

The blood pump shown in FIG. 6 has an impeller in the space of a housing 16, which is composed of a cylindrical pedestal 11 having a conical upper end surface and a plurality of blades 12 provided radially on the outer peripheral surface of the cylindrical pedestal 11. When the shaft 14 is rotated by a motor (not shown), blood flows like a blood flow 13 in the figure.

However, this blood pump has a pedestal 11.
Since a vortex flow 15 is generated near the outer periphery of the blood cell and a very large stress is applied to the blood cells, there is a problem that the blood cells are destroyed and hemolysis occurs.

On the other hand, the blood pump shown in FIG.
7 and a plurality of plate-shaped blades 18 radially provided on the curved surface from a position a certain distance away from the apex of the pedestal 17. When the shaft 20 is rotated by a motor (not shown), blood flows out. It has a structure in which blood flows like the blood flow 21 in the figure. In this blood pump, the bottom surface of the pedestal 17 is a housing 1 that accommodates the pedestal 17.
Since it has an area that covers almost the entire inner bottom surface of 2,
The generation of vortices as in the blood pump shown in FIG. 6 is not observed.

However, even with this blood pump, the occurrence of hemolysis cannot be effectively suppressed to a satisfactory level, and the blood ejection efficiency is also not sufficient. Furthermore, since the blade 18 is a curved plate (as viewed from above), there is a problem in that it is difficult to manufacture when integrally molded with the pedestal 17. The present invention has been made to improve the above situation.

That is, an object of the present invention is to provide a blood pump that is small, lightweight, easy to manufacture, has little hemolysis, has good discharge efficiency, and can be used safely for long periods of time. It is about providing.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of blades that are erected approximately radially on the curved surface of a substantially conical pedestal from a position a certain distance away from the apex of the pedestal. In a centrifugal blood pump having an impeller in a housing, the bottom surface of the pedestal has a diameter of 30 to 5 mm, covering almost the entire inner bottom surface of the housing.
The plurality of blades are each formed of a straight plate having an entrance angle of 20 to 50 degrees, and have a length L along the curved surface of the blade.
and a height H parallel to the rotational axis of the impeller at the radial tips of the radially arranged blades (L/H) is 2.5 to 6.0. It's a pump.

In the blood pump of the present invention, it is preferable that the diameter (R; unit: mm) of the pedestal and the ratio (L/H) satisfy the following relationship. 30≦R≦55, 2.5≦L/H≦6, L/H≧0.133R-2.33, L/H≦0.133R+0.51.

Furthermore, in the blood pump which is a preferred embodiment of the present invention, the substantially conical pedestal has a blood circulation hole penetrating from its upper surface to its lower surface.

[0014]

[Operation] In the blood pump of the present invention, since the bottom surface of the conical pedestal covers almost the entire inner bottom surface of the housing, there is no vortex flow of blood, and therefore less stress is applied to the blood.

[0015] Furthermore, since the pedestal is approximately conical and a straight plate is erected as a blade on this curved surface, the blood flows smoothly, and the blood flowing inside the blood pump is free from stress caused by, for example, shearing force or vortices. There is less stress. Furthermore, since the bottom surface of the pedestal is formed into a substantially circular shape with a diameter of 30 to 55 mm, the occurrence of hemolysis is effectively suppressed.

Further, the ratio (L/H) between the length L of the blade along the curved surface and the height H parallel to the rotation axis of the impeller at the radial tip of the radially arranged blades is 2. 5~
6, the discharge efficiency of the pump is good.

Furthermore, in the present invention, as shown in FIG. 2, the angle between the tangent of the circle connecting the tips on the blood inflow side and the tangent of the blade on the blood inflow side, that is, the inlet angle β is 20 to 50 degrees. Therefore, the occurrence of hemolysis can be suppressed while maintaining good pump discharge efficiency.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 shows a blood pump that is an embodiment of the present invention, and this blood pump belongs to the centrifugal pump type.

1 is a housing, 2 is a space for housing the impeller, 3 is a blood inlet port, 4 is a blood outlet port,
5 is a conical pedestal, 6 is a blade made of a straight plate, 7 is a shaft, 8 is a bearing, 9 is a V ring, 10
is an O-ring.

An impeller consisting of a pedestal 5 and blades 6 is rotatably housed in the space 2 of the housing 1, and when rotated by a motor (not shown) via a shaft 7, blood flows from the inlet port 3 into the space. 2 and exit port 4
It is configured so that it can be discharged more easily.

As shown in FIG. 2, the impeller has a structure in which a plurality of blades 6 are erected in a substantially radial manner on the curved surface of a substantially conical pedestal 5, and each blade 6 is arranged from the apex of the pedestal 5. It is formed from a position a certain distance d away to near the outer peripheral edge of the pedestal 5.

The impeller may be made of any material as long as it is lightweight, has sufficient strength, and reduces hemolysis.

Preferred examples include plastics such as polycarbonate resins, hard vinyl chloride resins, and polypropylene, particularly polycarbonate resins.

[0024] The pedestal 5 and the blades 6 are preferably manufactured by integral molding using such plastic.

[0025] Although it is called plastic, it is not preferable to use acrylic resin, which is often used in conventional blood pumps, because it may crack. In the present invention, the bottom surface of the pedestal 5 is approximately circular with a diameter of 30 to 55 mm, and it covers almost the entire inner bottom surface of the housing 1.

When the bottom surface of the pedestal 5 is formed into a substantially circular shape within the above range, hemolysis can usually be suppressed to 0.1 to 100 g/100 liters or less, and sometimes even to 0.05 g/100 liters or less.

If the diameter of the bottom surface of the pedestal 5 is less than 30 mm, hemolysis tends to occur; for example, if the diameter is 26 mm, the diameter of the bottom surface is 0.109
Hemolysis occurs at around g/100 liters.

Further, it is not preferable that the diameter of the bottom surface of the pedestal 5 exceeds 55 mm because the amount of priming becomes large. The apex angle α of the approximately conical pedestal 5 is 120 to 160.
It is better to take it as a degree. This is because if the apex angle α is less than 120 degrees, the pump efficiency will be poor, and if it exceeds 160 degrees, unnecessary vortices will tend to occur when blood flows in.

The preferred blade 6 according to the present invention satisfies the following conditions.

First, the blade 6 is not a curved plate but a straight plate.

When the blades 6 are constructed from straight plates in this manner, blood flows smoothly and hemolysis is reduced, and unlike the case of curved plates, they can be easily formed integrally with the pedestal 5.

The blades 6 are preferably formed at regular intervals on the curved surface of the base 5, and the number of blades is not particularly limited as long as it is plural, but it is usually about six.

Next, as shown in FIG. 2, this blade 6 has an angle between a tangent to a circle (broken line) connecting the tips of the blood inflow side 6a and a tangent to the blood inflow side 6a, that is, an inlet angle β of 20
-50 degrees, preferably 20-30 degrees.

When β is within this range, it is possible to suppress the occurrence of hemolysis while maintaining good pump discharge efficiency.

[0035] If β is less than 20 degrees, this is not preferable because the pump efficiency will deteriorate, and if β exceeds 50 degrees, the amount of hemolysis will increase, which is also not preferable.

Furthermore, as shown in FIG. 4, the blades 6 have a length L along the curved surface of the pedestal 5 and a height H parallel to the rotation axis of the impeller at the radial tips of the radially arranged blades. The ratio L/H must be in the range 2.5-6.

[0037] When this condition is satisfied, the blood pump of the present invention can maintain good discharge efficiency. On the other hand, when L/H is less than 2.5, the amount of hemolysis increases;
Exceeding this is undesirable because pump efficiency deteriorates.

In a more preferable blade 6, the diameter (R; unit: mm) of the pedestal and the ratio (L/H) satisfy the following relationship. The vane 6 that satisfies the following relationship has good pump discharge efficiency and can prevent hemolysis. 30≦R≦55, 2.5≦L/H≦6, L/H≧0.133R-2.33, L/H≦0.133R+0.51.

In the present invention, in addition to the above-mentioned conditions, it is also preferable to satisfy the following conditions.

First, regarding the blade 6, in order to reduce hemolysis without applying a large shearing force to the blood flow, the tip of the blood inflow side 6a forms an acute angle as shown in FIG. ) rather than a semicircle (if the wall thickness is R, the radius R
/2) It is better if the blood outflow side 6b is formed with a rounded shape, and when the impeller rotates in the direction A, one side B, which is in strong contact with the blood flow, is gently curved from the vicinity of the tip. It is better to have roundness.

Next, as is clear from the specification of the diameter of the pedestal 5 above, one of the objects of the present invention is to provide a small-sized blood pump.

The dimensions of each component are not particularly limited as long as they suit this purpose, but for example, if the maximum blood flow is 10
If you want to obtain a small blood pump of about liter/min, the diameter C of the blood inlet port 3 should be around 10 mm, the diameter D of the outlet port 4 should be 4 to 8 mm, and the height h of the pedestal 5 should be 6 to 12 mm.
It is desirable that the gap l between the blade 6 and the inner wall of the housing be 0.8 to 1.5 mm, and the inclination angle γ of the inner wall of the housing be about 30 degrees.

The present invention is not limited to the embodiments described above.

For example, the pedestal 5 may be provided with an arbitrary number of blood circulation holes penetrating from its upper surface to its lower surface.

FIG. 5 shows two blood circulation holes 5 as an example.
The pedestal 5 provided with a and 5a is shown.

Furthermore, in FIG. 1, the housing 1 may be divided into an upper housing 1a and a lower housing 1b, and the upper housing 1a may be used as a cap to detachably combine the housings.

Furthermore, in addition to the V-ring 9 and O-ring 10, an oil seal, a mechanical seal, or a modification thereof may be used as a sealing method.

[0048]

[Examples] The present invention will be explained in more detail below based on Examples and Comparative Examples.

(Example 1) A hemolysis test was conducted using the blood pump of the present invention constructed as shown in FIGS. 1 to 4, and the amount of hemolysis was measured.

[0050] The following impeller was used as the impeller of the blood pump.

Impeller material: Polycarbonate resin Outer diameter of pedestal: 36 mm Height of pedestal: 7.5 mm Inlet angle of vane: 20 degrees Vane length L Ratio of blade height H (L/H): 3.5 Number of blades: 6 The hemolysis test was conducted under the following conditions. (a) The differential pressure across the pump was kept constant at 100 mmHg. (b) The pump flow rate was measured every 1 liter/minute from 1 to 5 liters/minute. Note that this pump flow rate range is the range most often used as the amount of extracorporeal circulation by the cardiac assist device after open heart surgery. (c) During continuous operation for 5 hours, sampling was performed every 30 minutes, the amount of free hemoglobin in the plasma was measured by the SLS hemoglobin method, and the hemolysis index (I.H = Index
ofHemolysis) was calculated. In addition, I.
H represents the amount of change in free hemoglobin per 100 liters of pump discharge, and the allowable amount for biological applications is 0.1 g.
The following is considered. The results are shown in FIG.

Next, the blood pump of the present invention was operated and its output characteristics (pump discharge amount, differential pressure across the pump) were investigated. The results are shown in FIG.

(Comparative Example 1) A hemolysis test was conducted in the same manner as in Example 1 using the conventional blood pump shown in FIG.
The pump output characteristics were investigated. The material and dimensions of the impeller are the same as in the first embodiment.

The results of the hemolysis test are shown in FIG. 8, and the pump output characteristics are shown in FIG. 10.

(Comparative Example 2) A hemolysis test was conducted in the same manner as in Example 1 using the conventional blood pump shown in FIG.
The pump output characteristics were investigated. The material and dimensions of the impeller are the same as in the first embodiment.

The results of the hemolysis test are shown in FIG. 8, and the pump output characteristics are shown in FIG. 11.

(Example 2) A hemolysis test was conducted using the blood pump of the present invention constructed as shown in FIGS. 1 to 4, and the amount of hemolysis was measured.

[0058] The following impeller was used as the impeller of the blood pump.

Impeller material: Polycarbonate resin Outer diameter of pedestal: 50 mm Height of pedestal: 10 mm Blade inlet angle: 20 degrees Blade length L and blade height Ratio of height to H (L/H): 5.3 Number of blades: 6 Hemolysis tests were conducted in the same manner as in Example 1, and the output characteristics of the pump were investigated. . The results are shown in FIGS. 8 and 12 together with the results of Example 1.

(Evaluation) As shown in FIG. 8, the results show that in the conventional blood pump, the amount of hemolysis increases as the pump flow rate decreases, whereas in the blood pump of the present invention, the amount of hemolysis increases as the pump flow rate decreases.
5 liters/min in all ranges. H. The value of 0.1 g/100 liters, which is the permissible value, has been fully achieved.

The blood pump of the present invention exhibits a remarkable reduction in the amount of hemolysis compared to conventional blood pumps, especially in the low flow rate range of 2 liters/min or less.

As a result, it can be confirmed that the blood pump according to the present invention has a sufficiently reduced amount of hemolysis compared to conventional blood pumps, and can be used safely over a wide flow rate range.

[0063] Also, FIGS. 9, 10, 11 and 12
As is clear from the above, the blood pump of the present invention has better pump discharge efficiency than conventional blood pumps.

[0064]

[Effects of the Invention] The blood pump of the present invention is: (1) Since it is a centrifugal pump type blood pump, it is small, lightweight, and low cost, has few breakdowns, and can be used safely for a long time. (2) The generation of blood vortices is eliminated and the blood flow becomes smooth, so the amount of hemolysis is sufficiently reduced. (3) The impeller can be manufactured easily. (4) The pump Effects such as excellent discharge efficiency can be achieved.

Therefore, the blood pump of the present invention can be suitably used in an extracorporeal circulation circuit such as an artificial heart-lung machine or a cardiac auxiliary circulation device after open heart surgery.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an example of a blood pump of the present invention.

FIG. 2 is a plan view showing an example of the impeller of the blood pump of the present invention.

FIG. 3 is a plan view showing the blades of an impeller in an example of the blood pump of the present invention.

FIG. 4 is a configuration diagram showing main parts of the blood pump of FIG. 1.

FIG. 5 is a front view showing the pedestal of the impeller in another example of the blood pump of the present invention.

FIG. 6 is a sectional view showing an example of a conventional blood pump.

FIG. 7 is a sectional view showing another example of a conventional blood pump.

FIG. 8 is a graph showing the results of a hemolysis test using the present invention and a conventional blood pump.

FIG. 9 is a graph showing pump output characteristics of the blood pump of the present invention.

FIG. 10 is a graph showing pump output characteristics of a conventional blood pump (Comparative Example 1).

FIG. 11 is a graph showing pump output characteristics of a conventional blood pump (Comparative Example 2).

FIG. 12 is a graph showing pump output characteristics of the blood pump of the present invention.

[Explanation of symbols]

1 Housing 2 Space 3 Inlet port 4 Outlet port 5 Pedestal 5a　Blood circulation hole 6 Feather 6a　Blood inflow side vane 6b Blood outflow side blade 7 Shaft 8 Bearing 9 V ring 10 O-ring 11 Pedestal 12 Feather 13 Blood flow 17 Pedestal 18 Feather 21 Blood flow

Claims (3)

[Claims] Claim 1: A centrifugal pump type pump having an impeller in a housing, which has a plurality of blades erected approximately radially on the curved surface of a substantially conical pedestal at a certain distance from the apex of the pedestal. In the blood pump, the bottom surface of the pedestal has a diameter of 30 to 5 mm, covering almost the entire inner bottom surface of the housing.
The plurality of blades are each formed of a straight plate having an entrance angle of 20 to 50 degrees, and have a length L along the curved surface of the blade.
and a height H parallel to the rotational axis of the impeller at the radial tips of the radially arranged blades (L/H) is 2.5 to 6.0. pump. 2. The diameter (R; unit: mm) of the pedestal and the ratio (L/H) satisfy the following relationship:
The blood pump described in. 30≦R≦55, 2.5≦L/H≦6, L/H≧0.133R-2.33, L/H≦0.133R+0.51 3. The substantially conical pedestal has a blood circulation hole penetrating from its upper surface to its lower surface.
The blood pump described in.