JPH0255052B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pump type blood pump device such as an artificial heart or an artificial lung. 2. Description of the Related Art In recent years, progress has been made in the development of artificial hearts for auxiliary and temporary replacement of the functions of the heart, for example outside the body, during open heart surgery and other surgeries. In order for an artificial heart to be put into practical use, it is a prerequisite that the blood flow rate and its pressure waveform pumped out by a blood pump are sufficient to physiologically maintain blood circulation in a living body. That is, in order to function as an artificial heart, it is first necessary that the blood pressure curve exhibited by the blood pump be as close as possible to that of a natural heart, and most ideally, be the same. If the difference from the blood pressure curve exhibited by the natural heart is large, the response of the living body will exceed its limits and the patient will become unwell.
Very dangerous. Even more important is the effect on blood when using an artificial heart. That is, it is necessary not only to prevent thrombus from forming within the artificial heart during use, but also to minimize adverse effects such as hemolysis. What is important here is that patients who use such artificial hearts are usually extremely weak. Therefore, it must be noted that the heart reacts so sensitively that even the slightest difference from the natural heart can be fatal. For this reason, at least the period of use as an auxiliary artificial heart (1 to 2 weeks to 3 weeks)
It is necessary to minimize, preferably eliminate, the occurrence of abnormalities within 6 months). This is because even a small number of abnormalities can be fatal to the patient. In addition, with regard to blood pumps, tube type blood pumps have been proposed in addition to the sac type according to the present invention, but in this type, the walls of the tubes facing each other do not come into contact with each other due to the structure, and from the inlet. Blood is ejected unidirectionally to the outlet, and for this reason, blood that has flown in regardless of ejection due to contraction of the tube often flows out unaffected by the pulsation conditions, which reduces the assistive function of the living heart. There is a problem,
Furthermore, as the living heart recovers, it is necessary to lower the ejection flow rate, and this type of pump, in which the opposing wall surfaces do not come into contact with each other, has problems such as difficulty in ejecting smoothly. On the other hand, although the shape etc. of the sac-type blood pump device have been proposed, this pump does not have a collar to absorb the shock caused by the pulsation, so the joint between the blood chamber and the inlet/outlet tube, etc. In addition, there is no initial point of contact between the opposing walls of the blood chamber or structural conditions of the blood chamber to efficiently obtain this point, so vortex flow within the blood chamber does not occur smoothly and clots occur. There are problems such as easy to cause. The present invention has been made in view of such problems, and as shown in FIGS. 1 and 2, a pressure-resistant housing outer case 1 having ports 9 for introducing and discharging gas. A blood chamber 2 in the shape of a flat bag is airtightly housed through a collar 3 provided at the top thereof, and a blood introduction conduit 4 that communicates with the blood chamber 2 and extends above the collar; It is a sac-type blood pump device in which discharge conduits 5 are integrally arranged substantially parallel to each other, and the height L at the center line of the blood chamber 2, the maximum width D of the blood chamber, and the width of the blood chamber 2 are (1) 0.8≦D/L≦2.0 (2) 1.5≦D/W≦3.0, and the mutually opposing inner wall surfaces of the blood chamber The contour line of the narrow area surface that is configured to contact at least a predetermined portion and that constitutes the blood chamber 2 is composed of a straight line portion extending perpendicularly to the brim portion and a curved portion connected thereto, and The present invention relates to a sac-type blood pump device characterized in that the length l' of the section and the maximum width D of the blood chamber satisfy the relationship (3) 0≦l'<D. Embodiments of the present invention will be described below based on the drawings. The artificial heart of this embodiment is a so-called sac-type pneumatic artificial heart, and has a cylindrical pressure-resistant housing outer case 1 having a flat cross section, a blood introduction conduit 4, and a blood discharge conduit 5. It consists of a blood pump main body that is connected to the upper part of a blood chamber 2 that is parallel and flat, and a collar part 3 is provided between the blood chamber part 2 and the blood introduction and discharge pipes 4 and 5 for introducing and discharging the blood. The blood pump body is provided integrally with the tube, and the blood pump body is hermetically bonded to the pressure-resistant housing outer case 1 through this collar portion to form a blood pump. The blood introduction pipe 4 and the blood discharge pipe 5 are provided with check valves 6 and 7, respectively. In this case, the check valve 6 of the blood introduction pipe 4 is used for blood introduction, and the blood discharge pipe 5 is provided with check valves 6 and 7, respectively. Check valves 7 are respectively set for blood discharge. The collar 3 provided at the top of the blood chamber is airtightly attached by ultrasonic welding or adhesive. In this case, the flange portion 3 may be attached with screws. A port 9 for introducing and discharging air is provided at the lower part of the housing outer case 1, and a conduit is connected to this port 9. In this example, the artificial heart is driven by air, but it may be driven by carbon dioxide or other gases. To explain the operation of this artificial heart, first, air is forced into the housing outer case 1 through the port 9 to crush the blood chamber. Then, the blood in the blood chamber 2 is pushed out from the blood discharge conduit 5 through the check valve 7. At this time, the check valve 6 of the blood introduction conduit 4 is closed. Next, housing outer case 1
When the internal pressure is reduced, the blood chamber expands due to its elastic restoring force, increasing the volume of the blood chamber 2. Then, the check valve 6 of the blood introduction conduit 4 is opened, and blood is introduced into the blood chamber 2 from the blood introduction conduit 4. At this time, the check valve 7 of the blood discharge conduit 5 is closed. By sequentially repeating this operation, blood is pumped out periodically. The important point in this embodiment is that, as shown in FIG. 2, the cross-sectional shape of the blood chamber 2 is flat and that the blood chamber 2 has a shape within a certain range. In order for the blood pump to fully perform its function as an auxiliary artificial heart, the heart rate must be between 60 and 120 beats/min.
Therefore, the blood chamber 2 must perform contraction and expansion operations in exactly the same pattern for at least one month without any abnormalities occurring. In other words, through these countless heartbeats,
The behavior of ejecting blood from the blood chamber must remain constant at all times. What is more important is that the blood is not adversely affected during the introduction of blood into the blood chamber 2 and the ejection of blood from the blood chamber 2.
To this end, when blood is introduced into blood chamber 2, the dynamic flow behavior of the blood must be natural and reasonable, and the dynamic flow behavior when blood is pumped out must also be natural. That's good. At this time, if an unnatural flow or vortex stagnation occurs, blood reacts sensitively and adverse effects such as hemolysis occur. The degree of displacement of blood within the blood chamber 2 per stroke also affects blood damage. The inventor has developed a blood chamber 2 of an artificial heart pump.
The present invention was developed based on the findings of various investigations into the inward flow of blood, the shape of the blood chamber, and the phenomenon of hemolysis of blood.This point will be explained in detail with reference to FIG. FIG. 2A is a longitudinal cross-sectional view of the bag-shaped blood chamber 2 taken along its flat side (hereinafter referred to as "wide-area cross section"). FIG. 2B shows a vertical sectional view (hereinafter referred to as "narrow area cross section") in a direction perpendicular to the plane of FIG. 2A. The present inventor conducted various studies on the shape of the blood chamber that would pump blood most stably in the artificial heart in a behavior similar to that of a natural heart, and minimize unfavorable reactions to blood, as described below. It has been discovered that when these conditions are satisfied, adverse effects such as hemolysis on blood are extremely small, and blood pumping behavior can be very similar to that of a natural heart. In Figure 2, the height L at the center line of the blood chamber, the maximum width D of the blood chamber, the maximum thickness W of the blood chamber in an unloaded state, and the length l' of the straight part of the outline of the blood chamber in a wide area cross section. 0.8≦D/L≦2.0 Preferably -(1) 0.9≦D/L≦1.8 1.5≦D/W≦3.0 Preferably -(2) 1.8≦D/W2.5 0≦l'<D It has been found that very good results can be obtained if the following conditions are preferably satisfied: -(3) 0≦l'≦0.5D. In this figure, the collar part 3 of the blood pump may be integrally molded between the blood chamber part 1 and the conduits 4, 5, or may be integrally molded with the blood pump main body which is integrally molded as shown in FIG. 2A. A collar (FIG. 2C) which can be fitted in a hermetically tight manner may be fitted and hermetically adhered to the blood inlet and outlet conduits communicating with the blood chamber. In addition, in FIG. 2A, the concave shape from the flange 3 of the blood pump body to the highest point P of the center line of the blood chamber may be of various shapes, such as a semicircular shape as shown in FIG. 3A, or a concave shape as shown in FIG. 4. It may have a parabolic shape as shown in the broken line circle in B, or it may have an acutely pointed shape (FIG. 4A). From the perspective of blood flow, a smooth curve is preferable overall.
A semicircular or parabolic shape is preferable. The inventor has determined the maximum width D and height L of the blood chamber.
and the flow of blood in the blood chamber, and the degree of replacement of the blood in the blood chamber with newly introduced blood at each stroke (in other words, the ratio of blood that has been introduced into the blood chamber) They found that the ratio between the amount of blood remaining and the amount of blood remaining without pumping out is extremely important. Ideally, the whole blood in the blood chamber should be ejected with each ejection, and the flow of blood introduced should be such that it does not damage the blood. FIG. 3 is shown as an example of the present invention. The lower half of the wide-area cross section of the blood chamber has a semicircular shape with a radius of D/2, and the length of the straight section is set to l'=D/4. In this example, the space between the two conduits is also shaped to have a semicircular longitudinal section. The flow of blood will be explained using this diagram. First, blood is pumped out. When air is pressurized into the housing outer case 1, the blood chamber is compressed as shown by the broken line in FIG. Contact. The blood in the blood chamber is pumped out with a smooth concentric flow centered on this contact point as shown by the arrows in FIG. 3A. In order for this flow to proceed smoothly, the first point of contact between both wide-area surfaces of the blood chamber is important, and this point is on the vertical center line of the wide-area surfaces.
It must be between a height of 0.2L and 0.4L from the bottom of the blood chamber and always within a range of 0.15D in the width direction from the center line. In other words, if it deviates from this range, for example, when the bottom is the first contact point, the bottom part is likely to crack due to repeated violent pulsations,
Moreover, a smooth vortex as shown in FIG. 3 cannot be obtained. Furthermore, if the blood chamber is constructed so that the first point of contact is off to the upper side, the blood chamber as a whole becomes difficult to compress, making it impossible to obtain smooth pulsation. Furthermore, if the blood chamber is configured so that the first point of contact is located laterally than 0.15D, not only will a smooth vortex not occur, but blood will also have difficulty flowing from the inlet to the outlet. In any case, the result is unfavorable. Therefore, it is important to maintain a constant flow of blood within the blood chamber without causing unnatural vortices. For this purpose, the flatness of the blood chamber is important, and the D/W ratio must be in the range of 1.5 to 3.0. If this ratio is less than or equal to 1.5,
The point of contact on the large surface changes with each ejection, and for example, if this ratio is 1.0 (for example, if the blood chamber is cylindrical or light-shaped), the blood will change with each ejection of blood (in other words, each time the blood chamber is compressed). The initial contact point of the chamber is not constant, creating a complex vortex, and
The flow of blood is not always constant, and the blood is subject to hemolysis and other adverse effects. That is, when a bag-shaped blood chamber is crushed by air pressure, in the case of a cylindrical shape, the position at which the bag-shaped blood chamber starts to collapse is not determined, and the blood chamber is crushed as the bag-shaped member is crushed. The behavior of volume change also varies greatly each time, and furthermore, the phenomenon that the minimum volume of the blood chamber also changes each time pressurization occurs frequently. For this reason, it is difficult to maintain a constant blood output volume and blood pressure curve with an artificial heart of this type of structure. On the other hand, the oblateness (D/W) of blood chamber 2 is
If it is larger than 3.0, the expansion behavior of the blood chamber 2 becomes unstable when the pressure inside the housing 1 is reduced and the volume of the blood chamber 2 increases. Furthermore, if the blood chamber is too flat, too rapid a flow will be instantaneously applied to the blood, resulting in damage to the blood. Also, as already mentioned (as shown in Figure 3), the outline of the wide area cross section is important for the blood to flow, and the first contact point of the wide area surface when the blood chamber is compressed is important for blood flow. In order to generate a circular flow around
A curve that follows that flow is most ideal. In the example shown in Figure 3, the length l' of the straight part is set to D/4, but if this part is too long, the 5th
As shown in the figure, the direction of blood flow becomes unstable,
Each stroke produces a different flow. In order to prevent this, the inventor found that two requirements are necessary. One is the flatness (D/W) mentioned above, and the other is the relationship between the maximum width D and height L of the blood chamber, which is 0.8≦D/L≦2.0, more preferably 0.9<D/L≦1.8. It is necessary that Fig. 6 shows an example of the straight line part l' = 0 of the outer contour of a wide area cross section, and Fig. 7 shows an example of D/L = 0 in the same wide area cross section.
An example of 2.0 was shown. The outline of the blood chamber in FIG. 6 is an example formed by a parabola, and the height at the center line of the blood chamber reaches the brim. When the D/L ratio exceeds 2.0 (as indicated by the arrow in Figure 7), the blood flow does not flow in a circular shape within the blood chamber, and blood flows not only toward the left and right sides, that is, toward the blood outlet tube, but also toward the blood outlet tube. This is undesirable because it causes a flow that flows back toward the introduction pipe. Therefore, it is essential to fall within the range indicated in the present invention. When the above-mentioned requirements of the present invention are met, a constant flow of blood can always be produced in the blood chamber 2 with good reproducibility, and therefore blood flows through the check valve 7 with exactly the same behavior every heartbeat. It starts to get pumped out. In this way, it is necessary to always create a constant and stable blood flow within the blood chamber 2 in order to maintain antithrombotic properties and prevent hemolysis. The blood chamber part 2 and the conduits 4 and 5 used in this embodiment, that is, the parts that come into contact with blood, can be made of an elastic polymer material, and the material is as follows:
Particularly suitable are soft polyvinyl chloride or polyurethane. In this case, the soft polyvinyl chloride may be molded with a so-called polyvinyl chloride paste made of polyvinyl chloride and a plastic composition. Suitable plasticizers that can be used in this flexible polyvinyl chloride include dioctyl phthalate (DOP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dioctyl adipate (DOA), butyl phthalyl butyl glycolate (BPBG ), methyl acetyl ricionate (MAR), and acetyl tributyl citrate (ATBC).
In this case, the amount of plasticizer mixed is preferably 40 to 100% by weight, and 50 to 100% by weight based on the polyvinyl chloride.
More preferably, it is 80% by weight. The polyvinyl chloride may also contain suitable known stabilizers, such as non-toxic calcium-zinc organic complexes. It is preferable to use polyvinyl chloride having a degree of polymerization of 500 to 2000. The polyurethane used as the material in this example can be roughly divided into polyether polyurethane and polyester polyurethane, and both can be used, but polyether polyurethane is preferable from the viewpoint of elastic properties and fatigue resistance. is preferred. Since the blood chamber portion is required to have elastic properties, elastic recovery properties, and fatigue resistance properties, it is optimally made of polyether polyurethane. As the polyether part of the polyether polyurethane, polyethylene glycol, polypropylene glycol, pentamethylene glycol, diglyme, etc. can be used. In this embodiment, when the blood chamber part 2 is made of soft polyvinyl chloride, the film thickness of the blood chamber part 2 is preferably 0.3 to 2.0 mm, and 0.5 mm from the viewpoint of its repulsion characteristics and fatigue resistance. ~1.5mm
It is more preferable that it is, and even more preferably that it is 0.6 to 1.2 mm. In addition, if the blood chamber 2 is made of polyurethane material, the diameter is 0.2 to 1.5 mm.
The film thickness is preferably 0.3 to 1.2 mm, more preferably 0.3 to 1.2 mm,
Even more preferred is 0.5 to 1.0 mm. If this thickness is too large, when the inside of the housing outer case 1 is pressurized or depressurized, the timing of the operation of the blood chamber 2 will be delayed or the deformation time will be prolonged, so that appropriate blood pumping behavior will not be achieved. I can't. On the other hand, if this film thickness is too thin, the deformation behavior of the blood chamber becomes sensitive, making it difficult to control it. The check valves 6 and 7 used in this embodiment are as follows:
Any known or commercially available valve can be used. Such known or commercially available valves include ball type,
There are disk types, leaflet types, central flow types, etc. In the artificial heart of this embodiment, its compatibility with blood can be improved by coating its blood contact surface with a substance having excellent antithrombotic properties. For example, surface treatment with dimethylsiloxane, coating treatment with a polyether polyurethane-polydimethylsiloxane block copolymer, etc. may be performed. Although the present invention has been described above based on an artificial heart, the present invention can of course be similarly applied to an artificial lung and the like. Example 1 D/L for visually observing blood flow,
We prototyped a blood pump made of soft polyvinyl chloride with different D/W and l' values, and conducted experiments by attaching it to a model drive device. The thickness of the blood chamber wall is
It was 1.0mm. To observe the flow of blood, we added sodium polyacrylate, a nonionic surfactant, and a buffer to distilled water to create a liquid with a shear viscosity of 7 similar to blood, which is similar to the viscosity and surface tension of blood. Viscosity is 3.0~4.0cps between ~80sec ^-1
We prepared a product that changed to The surface tension of this liquid was 52 dynes/cm. A blood pump device was attached to a known model drive device, black ink was poured into the inside of the pump while it was being driven, and the flow was observed and the time required for the black ink to completely disappear from inside the pump was measured. The results are shown in Table 1. In this experiment, D=60mm.

【table】

[Table] As you can see from the table above, the better the flow, the faster the blood flow is replaced. It can also be seen that the flow is poor when the flow is outside the range specified in the present invention. Example 2 D/L was fixed at three points of 1.0, 1.2, 0.8, and D/W
= 2.0, various blood pumps were prototyped using segmented polyurethane. The wall thickness of the blood chamber was 0.8 mm. In this experiment, the length of l′ was varied. Second result
Shown in the table. In this experiment, D=60 mm. In addition, in experiments No. 22 to 28 (D/L = 1.0)
The first point of contact is 14.5mm from the bottom along the centerline
(0.24L) to 18mm (0.3L) and 3mm (0.05D) in both width directions from the center line, Experiment No. 30
The first contact point (D/L=0.8) at 34 is
The experiment was carried out in the range of 12.5mm (0.25L) to 14mm (0.28L) from the bottom and 5mm (0.08D) in both width directions.
The first contact point in No. 36 to 40 (D/L = 1.2) is 16.5 mm (0.22 L) to 23 mm (0.31 L) from the bottom.
and width in both directions within a range of 1.5mm (0.025D).

[Table] Example 3 A left heart bypass experiment was conducted using a regular dog weighing 16 kg using the pump shown in Figure 2 (the method was in accordance with the method described in Artificial Organs Vol. 7, p. 1208 (1978)). The size of the pump used in this experiment is D = 50 mm, W
= 25 mm, L = 45 mm, l' = 10 mm, l = 50 mm. As a result of examining changes in red blood cells, white blood cells, hematocrit, hemoglobin, and platelets after 5 hours using this method, no major changes were observed as shown in Table 3.

[Table] For reference, when a similar experiment was conducted with l' = 52 mm, the dog died in 2 hours due to blood clot.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the sac-type artificial heart according to the present invention, and FIG. 2 is a vertical cross-sectional view of a wide area surface (Figure A) and a narrow area surface (Figure B) of the blood chamber portion.
Figure C is a perspective view of the brim portion. Fig. 3 is a first embodiment of the present invention, Fig. A is a wide area longitudinal sectional view, Fig. B is a narrow area longitudinal sectional view and a view showing the mode of use thereof, and Fig. 4 is a diagram showing the embodiment of the present invention. This figure shows the shape of the center line of the blood chamber up to the highest point P, and Figure A shows an acute-angled tip, and Figure B shows a parabolic shape. FIG. 5 is a cross-sectional view showing the shape and mode of use when the length l' of the straight line part of the blood chamber part is greater than that specified in the present invention, and FIG. FIG. 7 is a cross-sectional view of the blood chamber section when the length is set to 0, and FIG. It is a figure showing an aspect. In the figure, code 1 is the housing outer case, 2
indicates the blood chamber, 3 indicates the collar, and 4 and 5 indicate the conduits.

Claims (1)

[Claims] 1. A flat bag-shaped blood chamber is airtightly housed in a housing outer case provided with ports for introducing and discharging gas through a flange provided at the top of the blood chamber. A sac-type blood pump device, which communicates with the blood chamber and includes a blood introduction conduit and a blood discharge conduit that are integrally disposed substantially parallel to the brim at the upper part of the brim. , 0.8≦D/L≦2.0 1.5≦D/W≦3.0 between the height L at the center line of the blood chamber, the maximum width D of the blood chamber, and the thickness W of the blood chamber in an unloaded state. and is configured such that the mutually opposing inner wall surfaces of the blood chamber are in contact within a range of 0.2L and 0.4L from the bottom and 0.15D from the center line in the width direction, and a sac-type blood characterized in that the length l' of the straight line portion of the narrow-area surface constituting the blood chamber extending perpendicularly to the brim satisfies the relationship 0≦l'<D. pump equipment.