JPH069662Y2 - Blood pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a blood pump. More specifically, it is compact, lightweight, low-cost, causes little hemolysis, and can be safely used for a long time, and is suitable for extracorporeal circulation circuits such as cardiopulmonary bypass and cardiac assist circulation after open-heart surgery. The present invention relates to a blood pump that can be used for.

[Problems to be solved by the prior art and device] Conventionally, as a blood pump for an extracorporeal circulation circuit such as a heart-lung machine or a heart assisting circulatory device after open heart surgery, a pulsatile pump type blood that supplies pulsatile flow is used. BACKGROUND ART Pumps and roller pump-type and centrifugal pump-type blood pumps that supply smooth flow are known.

The pulsatile pump-type blood pump supplies a pulsatile flow of blood by changing the inner volume of the blood chamber, which substitutes for the ventricle of the natural heart, by air pressure or mechanical means such as a pusher plate. Yes, it is classified into a diaphragm type, a sack type, a pusher plate type, etc. depending on the shape and volume changing means of the blood chamber.

Such a pulsatile pump type blood pump can supply blood with a flow rate waveform that is similar to the blood pumping pattern of the natural heart, as compared with a roller pump type or centrifugal pump type blood pump.

However, the pulsatile pump type blood pump requires a very expensive artificial valve for each of the inlet and outlet of the blood chamber, resulting in high cost and insufficient durability of the artificial valve. However, there is a problem that thrombus may be formed around the artificial valve. This problem has not been sufficiently solved even now, and has become a problem in the field of auxiliary circulation devices.

Further, the pulsatile pump-type blood pump is a control device for properly synchronizing the timing of blood extraction between the natural heart and the pulsatile pump-type blood pump in addition to the blood pump main body in order to reduce the load on the natural heart. is necessary. The pulsatile pump-type blood pump has the problems that the use of this control device makes the whole blood pump device large and heavy, and further increases the cost.

A roller pump type blood pump is a blood pump that squeezes a tube made of an elastic material such as vinyl chloride with one or more rollers to squeeze the tube and discharge the blood in the tube. It is widely used in the field of auxiliary circulation devices because it is easier to operate than a blood pump of a pump type or a centrifugal pump type.

However, the roller pump type blood pump has a problem in that the blood in the tube is squeezed to discharge the blood, resulting in destruction of blood cells and an increased amount of hemolysis.
Further, when used for a long time, a squeezed portion of the tube may be broken and blood may flow out to the outside, so that there is a problem that it is not possible to use for continuous operation for a long time.

On the other hand, a centrifugal pump-type blood pump is a blood pump that supplies a smooth flow according to the rotation speed of the impeller and the differential pressure across the pump by rotating the impeller in a pump chamber having an inlet port and an outlet port. Is.

This centrifugal pump type blood pump does not require an expensive artificial valve and does not require a control device unlike the pulsatile pump type blood pump. Therefore, it is possible to reduce the size, weight and cost of the blood pump. Therefore, unlike the roller pump type blood pump, there is no tube breakage, the blood pump has sufficient durability, and it can be sufficiently used for continuous operation for a long time.

Therefore, in recent years, this centrifugal pump type blood pump has been frequently used as a blood pump for an extracorporeal circulation circuit of a heart-lung machine or a heart assist device after open heart surgery.

As a conventional centrifugal pump type blood pump, for example,
Centrifugal pump type blood pump as shown in FIG.
There is a centrifugal pump type blood pump as shown in the figure.

The blood pump of FIG. 5 is provided with an impeller having a cylindrical pedestal 6l having a conical upper end surface and a plurality of blades 6m radially provided on the outer peripheral surface thereof. 34
It has a structure that flows like.

However, such a blood pump of FIG. 5 has a problem that a vortex 36 is generated in the vicinity of the outer periphery of the pedestal 6l, a very large stress is applied to blood cells, and hemolysis occurs.

On the other hand, the blood pump shown in FIG. 4 has an impeller composed of a pedestal 6j having a conical shape as a whole and a plurality of blades 6k radially provided on the conical surface. Blood flow 28
It is a structure that flows like. In this blood pump, since the bottom surface of the pedestal 6j has an area that covers almost the entire bottom surface of the housing 12 that houses the pedestal 6j,
Since there is no generation of vortex as in the blood pump shown in FIG. 5, there is no problem of hemolysis due to vortex.

However, the blood pump shown in FIG.
A stagnation portion 30 in which blood stays is formed between the pedestal 6j and the housing 12, and therefore heat generated in the seal member 32 is accumulated in the blood in the stagnation portion 30 and combined with the shearing force due to the rotation of the impeller. Therefore, there is a new problem that hemolysis occurs in the stagnation part 30.

As described above, the conventional centrifugal pump-type blood pump solves the problems in the pulsation pump and the roller pump, but because of the problems unique to the centrifugal pump-type blood pump as described above, It is hard to say that it has sufficient clinical performance. Specifically, for example, in the whole range of the blood flow rate of 1 to 8 / min where blood pumps are normally used, the amount of hemolysis is sufficiently small and stable performance cannot be maintained for a long time. Have.

Therefore, as a blood pump for an extracorporeal circulation circuit such as a heart-lung machine or a cardiac assist circulation device after open heart surgery, a centrifugal pump-type blood that can maintain stable performance for a long time with sufficiently little hemolysis. A pump is desired.

The present invention has been made based on the above circumstances.

That is, the purpose of the present invention is to be small, lightweight, low cost,
A centrifugal pump-type blood pump that does not cause hemolysis, can be safely used for a long time, and can be suitably used for an extracorporeal circulation circuit such as a heart-lung machine or a cardiac assist circulation device after open-heart surgery. To provide.

[Means for Solving the Problem] The invention according to claim 1 for solving the problem is a centrifugal pump-type blood pump including an impeller having a plurality of blades on a pedestal in a housing. The pedestal is a blood pump in which the bottom surface covers almost the entire bottom surface of the housing, the top surface is formed in a conical shape, and the pedestal has a blood circulation hole that penetrates from the top surface to the bottom surface. It is preferable that the center line of the blood circulation hole extending from the upper surface to the lower surface of the pedestal has a gradient of 5 ° to 30 ° with respect to the rotation axis of the impeller. (Claim 2) [Operation] In the blood pump of the present invention, since the pedestal is formed so that the bottom surface of the pedestal covers the entire bottom surface of the housing, there is no eddy flow of blood, and therefore, There is no eddy current stress on the blood near the impeller.

Further, since the pedestal has a plurality of blood circulation holes penetrating from its upper surface to its lower surface, the blood between the pedestal and the housing (on the side where the blade of the pedestal is not provided) circulates through the blood circulation hole, Retention is reduced and blood accumulation of heat from rotation near the impeller is also reduced.

In the blood pump of the present invention, when the center line of the blood circulation hole has a slope of 5 ° to 30 ° with respect to the rotation axis of the impeller from the upper surface of the pedestal to the lower surface, Blood retention is further reduced, and heat accumulation and hemolysis of blood in the vicinity of the impeller are further reduced.

Further, since the upper surface of the pedestal has a conical shape, the flow of blood is smooth, and the blood flowing in the blood pump is less subject to stress due to, for example, shearing force or vortex.

[Embodiment] A blood pump according to an embodiment of the present invention is of a centrifugal pump type, and for example, as shown in FIG. 1, has an inlet port 1 and an outlet port (not shown) for a liquid to be fed. A cap 4 having a blade 6h for rotating in a pump chamber 2 provided in the cap 4 and for feeding a liquid to be fed by a centrifugal force at the time of rotation is provided on an upper surface of a conical pedestal 6g with a conical vertex. A plurality of impellers provided between 6a and the outer peripheral edge of the pedestal 6g, a shaft 20 having a function of fixing the impellers and transmitting a rotational force, and allowing the impellers 6 and the shaft 20 to rotate. A housing 12 having a space for allowing the liquid to be fed and a seal member 8 for preventing the liquid to be fed from the pump chamber 2 into a bearing chamber 16 for rotatably supporting a shaft 20 provided in the housing 12. , Composed.

The conical pedestal 6g of the impeller is provided with a plurality of blood circulation holes 6i penetrating from the pedestal upper surface 6b to the pedestal lower surface 6e.

The shape of blood circulation hole 6i is not particularly limited, and may be, for example, a circular blood circulation hole as shown in FIG. 2, a square blood circulation hole, or any other shape.

If the size of the opening area of blood circulation hole 6i is too small, the effect of preventing blood from staying near the impeller may not be sufficiently exerted. Further, if the size of the opening area of the blood circulation hole 6i is too large, the effect of preventing blood vortex flow near the impeller may not be sufficiently exerted. However, the opening area of the blood circulation hole 6i such that the effect of preventing blood retention near the impeller is sufficiently exerted can be appropriately determined experimentally by those skilled in the art according to the scale of the blood pump. it can.

As a specific example, in a small centrifugal pump-type blood pump used in an extracorporeal circulation circuit such as a heart-lung machine and a postcardiac assisted cardiovascular system, the shape of the blood circulation hole 6i is shown in FIG. In the case of the circular shape as shown, the diameter of the blood circulation hole 6i is from 1/15 of the outer diameter D of the impeller.
It is preferably 1/8.

Further, in order to sufficiently exert the effect of preventing retention, as shown in FIG. 2, it is desirable that the blood circulation holes 6i be provided at equal intervals on a concentric circle with the rotation axis of the impeller. As shown in FIG. 1, the inner end portion 6C of the blood circulation hole is
It is preferably located at the same position as the outer diameter portion 8a of the seal member.

As a result, the fluid (blood) that has passed through the seal member outer diameter portion 8a passes smoothly through the blood circulation holes 8i in the outer diameter direction of the impeller, and the retention preventing effect can be further enhanced.

Further, in order to make the flow of blood in the pump smoother, the blood circulation hole 6i faces from the upper surface of the pedestal to the lower surface of the pedestal of the blood circulation hole as shown in FIGS. 1 and 3. The center line is 5 ° to 30 with respect to the rotation axis of the impeller.
It is preferred to have a slope A of °.

As a sealing method by the sealing member 8, any of a V ring, an oil seal, a mechanical seal, and a modification method thereof can be suitably used, and there is no particular limitation.

The blood pump shown in FIG. 1 has a configuration in which a V ring is used as the seal member 8.

A blood pump, which is an example of the present invention shown in FIG. 1, allows an impeller, a shaft 20, and a seal member 8 to rotate with respect to a housing 12, and a bearing in a bearing chamber 16 provided in the housing 12. A shaft 20 is supported by 14 and a bearing 18. The rotational force from the drive motor 24 is transmitted to the impeller 6 by the mechanical connection between the pin 22 and the shaft 20. The centrifugal force generated by the rotation of the impeller 6 causes blood to flow into the pump chamber 2 from the inlet port 1 of the cap 4 and is discharged from the outlet port (not shown).

The blood pump according to the embodiment of the present invention having the impeller shown in FIGS. 1 to 3 sufficiently exhibits the effect of preventing blood from staying near the impeller and the effect of preventing eddy currents. Blood retention and eddy currents are reduced.

In the blood pump shown in FIG. 3, arrows show the flow of blood.

Example 1 A hemolysis test was performed using the blood pump of the present invention having the above-described configuration, and the amount of hemolysis was measured.

The following impellers as shown in FIGS. 2 and 3 were used as the impellers of the blood pump.

Impeller Material: Polycarbonate resin Outer diameter of impeller (base): 26 mm Height of impeller base: 6 mm Number of blades: 6 Number of blood circulation holes: 6 Diameter of blood circulation holes 2 mm Center line gradient of blood circulation hole ... 20 degrees The hemolysis test was performed under the following conditions.

(B) The differential pressure across the pump was kept constant at 100 mmHg.

(B) The pump flow rate was 1 to 5 / minute and the flow rate was 1 / minute. The pump flow rate range is the most used range for extracorporeal circulation by the cardiac assist device after open heart surgery.

(C) During continuous operation for 5 hours, sampling is performed every 30 minutes, and the amount of free hemoglobin in plasma is measured by the SLS hemoglobin method, and the hemolysis index (IH = Index of Hemolys
is) was calculated. In addition, I. H represents the amount of change in free hemoglobin per 100 pump discharges, and the permissible amount for biological application is set to 0.1 g or less.

Results are shown in FIG.

(Comparative Example 1) Example 1 using a conventional blood pump as shown in FIG.
A hemolysis test was performed in the same manner as in, and the amount of hemolysis was measured. The material and dimensions of the impeller are the same as in the first embodiment.

Results are shown in FIG.

Comparative Example 2 Example 1 using a conventional blood pump as shown in FIG.
A hemolysis test was performed in the same manner as in, and the amount of hemolysis was measured. The material and dimensions of the impeller are the same as in the first embodiment.

Results are shown in FIG.

(Evaluation) As shown in FIG. 6, the result is shown in FIG. 6. In the conventional blood pump, the hemolysis amount increases as the pump flow rate decreases, whereas in the blood pump of the present invention, the hemolysis amount is 1 to 5 / min. I. range H. The value of is well within the allowable value of 0.1g / 100. In the blood pump of the present invention, the hemolysis amount is remarkably reduced as compared with the conventional blood pump particularly in the low flow rate range of 3 / min or less.

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

[Advantages of the Invention] According to the present invention, (1) the centrifugal pump type blood pump is small in size, light in weight, low in cost, has few failures, and can be safely used for a long time. ) The generation of blood vortex can be eliminated, and the stress on the blood in the vicinity of the impeller can be reduced, so that the amount of hemolysis can be sufficiently reduced, and (3) the retention of blood can be reduced. As a result, the heat accumulation of blood in the vicinity of the impeller can be reduced, hemolysis is significantly reduced, and long-term use can be supported. (4) Therefore, for example, a heart-lung machine or a heart after open heart surgery can be used. It is possible to provide a blood pump that has advantages such as being suitable for use in an extracorporeal circulation circuit such as an auxiliary circulation device.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an example of the blood pump of the present invention. FIG. 2 is an explanatory view showing an example of the impeller of the blood pump of the present invention. FIG. 3 is a sectional explanatory view showing an example of the blood pump of the present invention. FIG. 4 is a cross-sectional explanatory view showing an example of a conventional blood pump. FIG. 5 is a cross-sectional explanatory view showing an example of a conventional blood pump. Figure 6 shows
3 is a graph showing a hemolysis test result using a blood pump of the present invention and a hemolysis test result using a conventional blood pump in Examples. 1 ... Inlet port, 2 ... Pump chamber, 4 ... Cap,
6 ... impeller, 6a ... top of pedestal, 6b ... top of pedestal, 6c
...... Inside edge of blood circulation hole, 6d …… Peripheral edge of pedestal, 6e…
... Bottom surface, 6g ... Pedestal, 6h ... Vane, 6i ... Blood flow hole, 6j ... Pedestal, 6k ... Vane, 6l ... Pedestal, 6m ... Vane, 8 ... Seal member, 8a ... Seal member outer diameter part, 10 ...
… O-ring, 12 …… housing, 14 …… bearing, 16
…… Bearing chamber, 18 …… Bearing, 20 …… Shaft, 22 …… Pin, 24 …… Drive motor, 26 …… Blood flow, 28
...... Blood flow, 30 …… Stagnation part, 32 …… Seal member, 34 ……
Blood flow, 36 ... vortex, A ... gradient, D ... outer diameter of impeller.

Claims (2)

[Scope of utility model registration request] 1. A centrifugal pump type blood pump having an impeller having a plurality of blades on a pedestal provided in a housing,
The blood pump according to claim 1, wherein the pedestal has a bottom surface that covers substantially the entire bottom surface of the housing, a top surface that is conical, and a blood circulation hole that penetrates from the top surface to the bottom surface. 2. The center line of the blood circulation hole extending from the upper surface to the lower surface of the pedestal is 5 ° to 30 ° with respect to the rotation axis of the impeller.
The blood pump of claim 1 having a slope of °.