JP2002533184A - Improved integrated blood oxygenator and pump system - Google Patents

Abstract

SUMMARY An improved version of an integrated blood pump / oxygenator (120) having a rotating hollow filler bundle (127) assembling and pumping blood is provided. Internal members positioned along the central axis of the device accelerate blood entering the fiber bundle (127) to reduce microbubble generation and blood damage. The shear load imposed on the fiber elements of the fiber bundle (127) is reduced by the addition of the reinforcement structure. On the other hand, the gas flow path is configured to reduce the loss of oxygen supply efficiency due to flooding and temporary rupture of the fiber element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an extracorporeal system for oxygenating and pumping blood during cardiac surgery. More particularly, the present invention relates to an integrated oxygenator and pump system in which gas diffusion fibers form a pumping element.

BACKGROUND OF THE INVENTION [0002] Each year, hundreds of thousands of people suffer from vascular disease that causes cardiac ischemia (eg, arteriosclerosis).
Are suffering. For more than 30 years, such diseases, particularly those of the coronary arteries, have been treated using open surgical procedures (eg, coronary artery bypass grafting). During such a bypass implantation procedure, a sternotomy is performed to access the pericardial sac, the patient is placed on a cardiopulmonary bypass, and the heart is stopped using a cardiac arrest solution.

In recent years, for example, Heartport, Inc. , Redwood City,
California and CardioThoratic Systems,
Inc. The development of a minimally invasive technique for cardiac bypass transplantation, by Menlo Park, California, has put a premium on reducing the size of the devices used in this sterile field. Typically, open surgical techniques provide a relatively large surgical site for direct viewing by the surgeon, while minimally invasive techniques involve endoscopes, video monitors, and various positioning tools for these instruments. Need a system. These devices can fill the sterile field and limit surgeon operability.

However, at the same time, due to the need to reduce the priming capacity of oxygenators and pumps and the desire to reduce blood contact with non-native surfaces,
There is increasing interest in placing oxygenators and pumps as close as possible to the patient.

In recognition of the foregoing problems, some previously known cardiopulmonary systems have attempted to downsize and integrate certain components of the cardiopulmonary system. U.S. Patent No. 5,266,265 and U.S. Patent No. 5,270,005
No. 1 (Raible) has an integrated blood reservoir, an oxygenator formed from a static array of hollow fibers, a heat exchanger, a pump, and a pump motor controlled by a cable connected to a control console. An oxygen supply system is described.

The systems described in the aforementioned patents use relatively short flow paths. This can result in insufficient gas exchange due to the development of a laminar flow zone adjacent to the hollow fibers. U.S. Patent No. 5,411,706 (Hubbard et al.) Discloses one method of providing a longer flow path by recirculating blood through a fiber bundle at a faster flow rate than blood is delivered to a patient. Describe the solution. U.S. Pat. No. 3,674,440 (K
and U.S. Pat. No. 3,841,837 (Kitril).
Akis et al.) describe an oxygenator that forms an active element that agitates blood so that the gas transfer surface prevents the formation of a boundary layer around the gas transfer surface.

[0007] Makarewicz et al., "A Pumping Intravascula.
r Artificial Lung with Active Mixing
, "ASAIO Journal, 39 (3): M466-M469 (199).
3) describes an intravascular device having a gas exchange surface made of microporous fibers formed in elongated helical vanes. This elongated spiral vane can be rotated to not only allow gas exchange, but also to pump blood through the device.

[0008] Makarewicz et al., "A Pumping Artificial L
ung, "ASAIO Journal, 40 (3): M518-M521 (
1994) describes a modification of the aforementioned device in which a microporous fiber bundle is formed in a multi-lobed clover leaf vane positioned along a central axis. This vane is B
IOMEDICUS® Blood Pump (Bio-Medicus, Ede
n Prairie, a trademark of Minnesota). The authors found that the concept of achieving simultaneous pumping and oxygenation appeared feasible, but required further design and testing, and had to address issues such as hemolysis and platelet activation. Concluded.

[0009] Makarewicz et al., "New Design for a Pumpi.
ng Artificial Lung, "ASAIO Journal, 4
2 (5): M615-M619 (1996) describes an integrated pump / oxygenator where hollow fiber bundles replace the multi-lobe vanes of the above design. A hollow fiber bundle is placed against the inlet gas manifold at the bottom and the outlet gas manifold at the top. The fiber bundle is rotated at a high speed to provide a pumping action, while oxygen passing through the fiber bundle oxygenates the blood.

US Pat. No. 5,830,370 (Maloney et al.) Describes a device having a fiber bundle mounted for rotation between a fixed central diffusion element and an outer wall of a housing. The fiber bundle is rotated at a speed high enough to create a shear force that induces turbulence in the blood. This patent does not address or even recognize the problem of blood damage (ie, hemolysis and platelet activation) that is expected to result from turbulent high shear flow.

While the devices described in the aforementioned references provide some desirable features,
These devices have a number of drawbacks that make them commercially impractical. These problems include: (a) the introduction of small bubbles ("microbubbles") from the fibers into the blood due to the higher gas side pressure relative to the blood side pressure; (b) due to cavitation Induced blood damage and damage to the device; (c) high shear loading (which leads to (i) fiber bending or (ii) blood damage); and (d) flooding of the inlet gas manifold after fiber rupture ( Causing a rapid drop in oxygen supply efficiency).

[0012] In view of the foregoing, an extracorporeal blood pump / which provides the ability to fully oxygenate blood using a compact size, low priming capacity, low surface area, and rotating fiber bundles that reduce boundary layer transition resistance It is desirable to provide an oxygenator.

An integrated extracorporeal blood pump with a hollow fiber bundle that oxygenates the blood and provides a pumping action when rotated, but does not suffer from gas leakage into the blood (leading to undesirable foam formation) It is desirable to provide a / oxygenator.

A hollow fiber bundle that oxygenates the blood and provides a pumping action when rotated, but overcomes the problem of microbubble generation observed in previously known integrated pump / oxygenator systems It would also be desirable to provide an integrated extracorporeal blood pump / oxygenator having

It is an object of the present invention to provide an integrated extracorporeal blood pump / oxygenator having a hollow fiber bundle design that does not produce high shear stress, and is therefore less susceptible to shear-induced fiber breakage and resulting leakage. More desirable.

It is further desirable to provide an integrated extracorporeal blood pump / oxygenator having a hollow fiber bundle design that reduces shear-induced blood damage (including hemolysis and platelet activation).

It is even more desirable to provide an integrated extracorporeal blood pump / oxygenator with a rotating hollow fiber bundle that is less susceptible to gas manifold flooding than previously known designs.

It is further desirable to provide an integrated extracorporeal blood pump / oxygenator with low priming capacity, and thus create a suitable system for emergency backup operations.

SUMMARY OF THE INVENTION In view of the foregoing examples, it is an object of the present invention to provide a rotating fiber bundle that reduces the size, the amount of priming and the boundary layer resistance to gas transfer and the formation of stagnant zones within the fiber bundle. To provide an integrated extracorporeal blood pump / oxygenator with the ability to properly oxygenate the blood.

[0020] Another object of the present invention is to provide an integrated extracorporeal blood pump / oxygenator having low priming volume and small internal surface area, thereby contacting non-native surfaces of blood, Reduces potential damage to components and risk of infection.

Yet another object of the present invention is to provide a hollow fiber bundle which oxygenates blood and provides a pumping action when rotated, but which forms bubbles to reduce gas leakage into the blood. To provide an integrated extracorporeal blood pump / oxygenator.

It is a further object of the present invention to provide an integrated extracorporeal blood pump / oxygenator having a hollow fiber bundle that oxygenates blood and provides a pumping action when rotated. Overcomes the microbubble generation problem observed in previously known integrated pump / oxygenator systems.

It is a still further object of the present invention to provide an integrated extracorporeal blood having a hollow fiber bundle that is less susceptible to fiber breakage or buckling due to high shear forces and resulting leakage on individual elements of the fiber bundle. It is to provide a pump / oxygenator.

Yet another object of the present invention is to provide an integrated extracorporeal blood pump / oxygenator with a hollow fiber bundle design that reduces shear-induced blood damage.

It is yet another object of the present invention to provide an integrated extracorporeal blood pump / oxygenator with a rotating hollow fiber bundle that is less susceptible to gas manifold flooding than previously known designs.

Another object of the present invention is to provide an integrated extracorporeal blood pump with low priming volume /
Providing an oxygenator, thereby creating a suitable system for emergency backup operations.

[0027] These and other objects of the present invention are achieved by providing an integrated extracorporeal blood pump / oxygenator suitable for use in a sterile area and having a low priming volume. . In accordance with the principles of the present invention, the pump / oxygenator includes a rotatable hollow fiber bundle assembly that oxygenates the blood and generates an additional pressure head (if desired) for pumping the blood. The device further includes one or more of the following improvements: means for reducing microbubble generation and blood damage;
means for reducing d bowing); and means for reducing gas manifold flooding.

In a preferred embodiment, the integrated blood pump / oxygenator increases the pressure on the blood side relative to the gas side near the center of the fiber bundle, thereby preventing the formation of gas microbubbles in the blood A tapered inner member disposed along a central shaft. The inner member, which may optionally include a helical vane, also gradually accelerates the blood before entering the fiber bundle, thereby reducing blood damage. Shear loads that are pressed against the fiber elements of the rapidly rotating fiber bundle are handled by the addition of reinforcement structures that extend around or into the fiber bundle. These reinforcement structures also assist in reducing the shear stress applied to the blood, thereby reducing blood damage. Further, the gas manifold of the pump / oxygenator may be optionally configured to reduce the loss of effectiveness due to flooding and occasional rupture of the fiber element.

An alternative embodiment of the integrated extracorporeal blood pump / oxygenator of the present invention may include multiple vanes for accelerating blood entering and / or leaving the fiber bundle. These vanes can be coupled to the same shaft that drives the rotating fiber bundle, or can be driven at different angular velocities as needed using separate drive trains.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an integrated blood pump / oxygenator that overcomes the shortcomings of previously known devices. In accordance with the principles of the present invention, the integrated system can be located in or near a sterile area and has a low priming volume (eg, 250 cc).
Less than). A pump / oxygenator constructed in accordance with the principles of the present invention is expected to: (a) produce little or no gas leakage into the blood and resulting bubble formation; (B) experience little or no cavitation, even at high speeds; (c) little tendency of the fiber element to burst; (d) little or no blood damage And (e) provide adequate oxygen supply capacity, even in the event of occasional rupture of the fiber element.

Referring to FIGS. 1 and 2, Makarewicz et al., “New De,” supra.
A previously known integrated blood oxygenator / pump 1 in a paper entitled "Sign for a Pumping Artificial Lung," 1
0, which is incorporated herein by reference in its entirety. The pump / oxygenator 10 includes a shield housing 11 having a blood inlet 12, a blood outlet 13, a gas inlet 14, and a gas outlet 15. The hollow fiber bundle 16 is mounted at the bottom on the inlet gas manifold 17 and the outlet gas manifold 18 is mounted on the top. The hollow fiber bundle is BIOMEDICU
S® blood pump replaces vane (Bio-Medicus, E
den Prairie, a registered trademark of Minnesota). As is well known to those skilled in cardiopulmonary bypass, the Bio-Medicus pump includes a magnet 19 located in a tray 20 that is magnetically coupled to a magnet attached to a drive shaft (not shown).

Blood entering pump / oxygenator 10 via inlet 12 passes through central void 21. As the fiber bundle 16 is rotated, blood is drawn into the fiber bundle 16 by centrifugal force, accelerating blood to pass through the fiber bundle, and exiting the pump / oxygenator through the blood outlet 13.
Oxygen flows through gas inlet 14 to manifold 17 from which blood is distributed to the individual fibers of the fiber bundle. As blood passes through the fiber bundle 16, carbon dioxide diffuses through the pore walls of the hollow fiber into the fiber, while oxygen diffuses from the fiber bundle into the blood. Residual oxygen and carbon dioxide pass through the outlet gas manifold 18 and may be vented therefrom through the gas outlet 15 to the atmosphere.

The pump / oxygenator of FIGS. 1 and 2 has several highly desirable features (
(Including a small amount of priming and a small surface area), Applicants have determined that the device has a number of drawbacks that make it commercially impractical. However, Applicants have also discovered various improvements that overcome their drawbacks, and the improvements described hereinafter are similar to the pump / oxygenator of FIGS. / Hope that the oxygenator can be a commercially viable product.

A first drawback of the device of FIGS. 1 and 2 is that it creates microbubbles, ie rotation of the fiber bundle that induces a low pressure region that draws gas bubbles from the gas side through the pore membrane from the blood side to the blood side. This is the tendency. Specifically, rotation of the fiber bundle 16 causes a low pressure region to form within the central nucleus 21, which in turn pulls gas bubbles through the membrane of the fiber element closest to the center. In addition, the formation of localized low-pressure regions can induce classical cavitation, ie, the formation of a gas phase in the form of microbubbles. Bubbles not only annoy at the inherent danger, but can also bubble blood if not filtered before perfusing the patient, thereby reducing oxygenation efficiency.

A second disadvantage of the devices of FIGS. 1 and 2 is that the individual fiber elements tend to flex radially outward during rotation of the fiber bundle. Depending on the speed of rotation of the fiber bundle, the forces generated in the fiber bundle can be very high and the fiber can be frequently pulled from the pot or broken. This in turn causes a leak of blood into the inlet gas manifold.

[0036] Leakage from loose or broken fibers can cause a third and significant problem in the previously known devices described above. In particular, a large amount of blood leaking into the inlet gas manifold 17 or the outlet gas manifold 18 through broken or loose fibers will cause these gas manifolds to flood, thereby causing oxygen to the fiber bundles Shut off the supply and render the device inoperable.

In addition, even if blood leaks into the gas manifold through a relatively small number of fibers, rotation of the fiber bundle urges blood radially outward and collects along the outer perimeter of fiber bundle 16. Let This stored blood is
The fiber element is then shut off from the gas flow. The area affected by the pooled blood is directly proportional to the radius, and flooding at the outer end of the fiber bundle results in a rapid decrease in oxygenation efficiency.

[0038] Yet another significant disadvantage of the devices of FIGS. 1 and 2 is that the high shear applied to the blood results in undesirable blood trauma, including hemolysis and platelet activation. This high shear stress and the resulting blood trauma occurs primarily where blood enters and exits the fiber bundle. When entering the fiber bundle, the blood collides with the rapidly rotating fibers of the fiber bundle,
And are therefore rapidly accelerated by these collisions. Also, as blood exits the fiber bundle, it is exposed to high levels of shear at the interface between the fiber bundle and the inner wall of the housing. This may be especially the case when there is an outward deflection of the fiber bundle, where the deflection reduces the clearance between the outside of the fiber bundle and the inner wall of the housing.

Referring now to FIG. 3, an apparatus constructed in accordance with the present invention is described.
The pump / oxygenator 30 of the present invention includes the above-incorporated Makarewicz.
Several improvements to the devices described in these articles (useful individually or in combination) include those that overcome the above problems. Pump / oxygenator 30 is magnetically coupled to drive shaft 31 of motor 32, which is then controlled by controller 33. Deoxygenated venous blood is supplied to the pump / oxygenator 30 via a suitable biocompatible tube (not shown) connected to a venous blood inlet 34; From the oxygenator 30, it is returned to the patient through a biocompatible tube (not shown) connected to the blood outlet 35.

The pressurized oxygen is introduced to the pump / oxygenator 30 via the gas inlet port 36, while the mixture of oxygen and carbon dioxide is pumped via the gas outlet port 37 to the pump / oxygenator Exit 30. Motor 32, magnetically coupled drive shaft 31, and controller 33 are articles known per se in the art,
And Bio-Medicus, Inc. , Eden Prairie, Min
It may comprise any of a number of systems available from Nesota. Alternatively, drive shaft 31, motor 32, and controller 33 may be miniaturized to allow their placement closer to the patient.

Referring now to FIGS. 4A-4B and FIGS. 5A-5D, the internal arrangement of the integrated pump / oxygenator 30 of the present invention will be described. The pump / oxygenator 30 includes a fiber bundle assembly 4 rotating on a shaft 42 inside a housing 40.
In one form, a housing 40 including a gas transfer element is provided. Shaft 42
Is fixed to a shaft impeller 65, which is mounted on the tray 44. The tray 44 holds one or more magnets 45, which are used to magnetically couple the fiber bundle assembly 41 to the drive shaft 31 (
See FIG. 3).

The fiber bundle 46 preferably has an annular shape formed from a multiplicity of microporous hollow fiber elements and includes a central void 46a. The upper end of the hollow fiber element is placed in region 47 such that the inner lumen of the fiber communicates with void 48 in inlet gas manifold 49. Similarly, the lower end of the hollow fiber element of fiber bundle 46 is placed in region 50 such that the inner lumen of the fiber communicates with void 51 in outlet gas manifold 52. Any of a number of suitable biocompatible potting materials (eg, polyurethane or epoxy) can be used.

The shaft 42 includes an inner tube 53 and an outer tube 54 that are coaxially arranged to form a ring. The annulus 55 communicates with the gas inlet port 36 (shown in FIG. 3) through a hole 57 through the wall and the inlet gas manifold via a hole 59 through the wall and a passage 60 in a plurality of pumping vanes 61. It communicates with 49 voids 48. The lumen 62 of the inner tube 53 communicates at its upper end with the gas outlet port 63 and communicates with the void 51 in the outlet gas manifold 52 at its lower end via a passage 64 in the shaft impeller 65. The shaft seal 66a is
A space 67 is separated, which connects the gas outlet port 63, from the space 68, to the lumen 62, which connects the gas inlet port 36 (shown in FIG. 3) to the annulus 55. The shaft seal 66b divides the space 58 into the fiber bundle assembly 4.
1 from the interior of the housing 40 containing the same. Shaft seals 66a and 66b are maintained by seal caps 66c and 66d, respectively (FIG. 5A).
See).

The shaft 42 is held by bearings 69, while the shaft impeller 65 is held by bearings 71 and 72. Thrust washer 73 is placed between bearings 71 and 72, and then the entire assembly is held on bearing shaft 74. The bearing shaft 74 is fixed to the lower plate 75 of the housing 40 by shoulder screws 76 and rests on an O-ring seal 77. The shoulder screw 76 is also sealed with an O-ring 78. The shaft impeller 65 seals the lower end of the ring 55, while the upper end of the ring is sealed by a plug 79.

The shaft impeller 65 (shown in FIG. 5B) forms an inner member that radially displaces blood entering the central void 46a and includes an upper hub 80 and a lower hub 80a. The upper hub 80 is connected to the upper potting 47 and the lower hub 80a is connected to the lower potting 50. A pumping vane 61 can be optionally incorporated on the hub 80 and extends helically downward to form a vane 90. FIG. 5C shows an alternative embodiment of the shaft impeller 65, where the pumping vanes 61 also optionally extend above the hub 80. The openings 85 between the plurality of vanes 61 allow blood to enter the pump / oxygenator 30 via the venous blood inlet 86 and flow into the fiber bundle 46. Vane 61 is configured to act as a vane that pumps and accelerates blood passing through fiber bundle 46. As will be appreciated, the pump housing and seal location must be appropriately modified to accommodate the extended vane 61 of FIG. 5C.

In accordance with the principles of the present invention, pump / oxygenator 30 includes a number of features that overcome the disadvantages observed with the devices of FIGS. These improvements can be used individually or in combination, depending on the intended application of the pump / oxygenator.

To reduce the microbubble generation and shear-induced blood trauma of the previously known device shown in FIGS. 1 and 2, the conical tapered portion 65a of the shaft impeller 65 is connected to the hubs 80 and 80a. Blood side pressure between
resourcing). If necessary, a plurality of vanes 61
And 90 may be disposed on the impeller shaft 65 to further reduce the foam formation previously observed in previously known devices, by increasing the pressure of the blood entering the fiber bundle 41, faster. Shaft impeller 6
5 also reduces blood trauma by progressively accelerating the penetration of blood into the hollow fiber bundle, thus reducing the risk of blood impingement on the rotating bundle in previously known designs. It is expected to reduce the high shear forces encountered. Additionally or alternatively, the pressure at which blood is supplied to the pump / oxygenator 30 may be increased, for example, by using an auxiliary pre-pump, as described below with respect to FIGS. .

To reduce the flooding problem encountered in the previously known devices of FIGS. 1 and 2, the locations of the inlet and outlet gas manifolds are such that the voids 51 formed by the outlet gas manifolds 52 have internal voids 51. Can be inverted as needed to couple to lumen 62 of tube 53 (for the designs of FIGS. 1 and 2)
. Further, the baffle plate 91 may be disposed in the void 51 and includes a groove 92 on its lower surface that communicates with the passage 64. Baffle plate 91, when present, allows gas exiting fiber bundle 46 to pass around the outermost end of the baffle plate. Thus, blood leakage of the outlet gas manifold into the void 51 is eliminated from the manifold and entrained in the exhaust stream passing through the gas outlet port 63.

The support structure preferably comprises a fiber bundle assembly to reduce pressure induced failure such as encountered in previously known devices for fibers and to reduce fibers pulled without potting material. 41
Placed around. Referring to FIG. 5A, fiber bundle assembly 41
And shaft 42 is shown without housing 40. A girdle 95, which may include a collar and sleeve made of a suitable biocompatible material (eg, metal or plastic), is placed around the fiber bundle 46. Girdle 9
5 is preferably potted using fiber bundles 46 in the inlet and outlet gas manifolds.

In accordance with the principles of the present invention, girdle 95 reduces radial deflection of the fiber elements of fiber bundle 46 when pump / oxygenator 30 is operated at high speed. Thus, the girdle 95 reduces the strain on the fiber element, prevents the fiber element from contacting the interior surface of the housing, and reduces the risk of the fiber element being pulled or otherwise broken without potting material. Decrease. The girdle 95 is expected to reduce the number of fiber elements that break, thus reducing the risk of flooding. With the combination of the baffle plate 91 and the above-described reverse gas flow passage, it is expected that the pump / oxygenator 30 will maintain high gas exchange efficiency even in the presence of a nominal number of broken fibers.

Referring to FIG. 5D, fiber bundle 46 preferably includes a hollow fiber mat 96 that includes a number of fibers 97 interconnected by threads 98. In one preferred embodiment, the fiber bundle 46 wraps a hollow fiber mat 96 around the hubs 80 and 80a and then frees the mat against the next inner layer using a suitable biocompatible adhesive. It is formed by sealing the edges. The girdle 95 is then, as described above with respect to FIG.
It can be placed around the outer circumference of the fiber bundle. Or or girdle 9
In addition to 6, the fiber bundle may be strengthened by gluing or heat sealing the overlapping areas of the fiber mat. By radially arranging such bonded areas, the structural integrity of the fiber bundle is sufficiently increased to reduce outward bow, but to reverse the outward movement of blood through the fiber bundle. Has no effect.

In addition, the support structure described above helps to reduce blood damage by maintaining a proper spacing between the outer surface of the fiber bundle and the inner wall of the housing. Specifically, these structures are expected to impart a radially inward force imposed on the blood and to avoid the high shear stress imposed on the blood, where the fiber bundle The curved portion rotates very close to the inner wall of the housing and / or contacts the inner wall.

Referring now to FIG. 6, a shaft 100 suitable for use in an alternative embodiment of the present invention will be described. The shaft 100 is similar to the configuration for the shaft 42 of FIG. 5C, except that the shaft 100 includes a plurality of vanes 101 located above the pumping vanes and acceleration vanes 102. Vane 10
1 is designed to increase the pressure of blood flowing along the shaft 100, thereby further reducing the potential for cavitation, foaming and blood damage during high speed operation. Of course, as the intent is understood, the pump housing must be modified to be compatible with vane 101 and vane 1
The number, shape and orientation of 01 may be chosen empirically to provide adequate flow rates and pressure heads and to further reduce blood damage.

In FIG. 7, a further alternative embodiment of the pre-acceleration vane is illustrated. In this embodiment, the shaft 110 and the acceleration vanes 111 provide the functions described above with respect to the tapered portion 65a of the shaft impeller 65 of the embodiment of FIGS. Shaft 112 includes a hollow tube coaxially disposed with shaft 110 and includes a plurality of vanes 113. The shaft 112 is
For example, it may be driven at the same or a different angular speed as shaft 110 by a separate motor via a suitable transmission or belt arrangement. As a result, vane 11
The amount of pre-acceleration provided by 3 can vary as a function of the rotational speed of the fiber bundle. Although the number, orientation and shape of the vanes 113 can be determined empirically, other modifications to the pump / oxygenator 30 that may be required to practice the present invention will be apparent to those skilled in the art of pump design, from investigations. it is obvious.

Alternatively or additionally, vane 113 and housing 40 may be connected to vane 11
3 and shaft 112 function as separate pumps, the outlets of which can be directed to the fiber bundle via accelerating vanes 111, or via suitable valving in the direction of returning the patient to perfuse. May be configured to obtain. In this manner, the pump / oxygenator of the present invention may be used to partially remove the heart, for example, during a beating heart procedure, and then fill the patient during the cardiac arrest phase of the procedure. Isolated cardiopulmonary artery (cardiopulmonary)
Put in bypass.

Referring now to FIGS. 8-11, a preferred embodiment will be described in which the plurality of vanes 113 of FIG. 7 are provided as separate backup pump elements. 8A and 8B
A pump / oxygenator 120 constructed in accordance with the principles of the present invention is described, wherein the generation of microbubbles in the central void of the gas transfer element uses a separately driven pre-pump. Is reduced. The pump / oxygenator 120 also illustratively includes a heat exchanger for heating or cooling the blood, depending on the stage of cardiac surgery. The pump / oxygenator 120 preferably has a motor drive 121a
And 121b are magnetically coupled, and these motor drives are programmably controlled by a controller 122. Controller 122 includes a microprocessor 123 and a display / input console 124 and may include, for example, an LCD screen and a keyboard.

Referring to FIG. 8A, pump / oxygenator 120 includes a housing 125 having a compartment 126 containing a rotating fiber bundle 127 and a compartment 128 containing a centrifugal pump 129. The compartment 128 is preferably connected to the compartment 126 by a passage 130 so that the outlet of the centrifugal pump 129 is directed to the central void 131 of the fiber bundle 127. Blood is delivered to device 12 via blood inlet 132.
Enters zero and exits via blood outlet 133.

The oxygen-rich gas mixture enters via a gas inlet port 134 and the oxygen-depleted, carbon dioxide-rich exhaust gas exits via a gas outlet port 135.
Heated or cooled water (depending on whether it is desired to warm or cool the blood as required at a given stage of surgery) is coiled through water inlet port 137 Enters the tube 136 and exits through a water outlet port 138. For example, if the fiber bundle is allowed to remain stationary during a cardiac procedure, port 139 may be used to evacuate air from compartment 126 during priming of device 120, and In response to the,
Port 139 may be used to introduce fresh blood into compartment 126 to flush stagnant blood. The blood pressure in the central void of the fiber bundle 127 can be monitored, and the gas that accumulates in the central void 131 is exhaust gas 1
Via 40, it can be evacuated. Applicants believe that during prolonged operation of a rotating fiber bundle device (eg, as described in FIGS. 4 and 8), such microbubbles, such as those formed within the device, may cause the central void 131 It was observed that there was a tendency to fuse near the center. Exhaust port 140 and line 1 connected thereto
The 41 extends into the top of the central void 131 and may be advantageously used to exhaust no matter how gas collects in the pump / oxygenator 120.

Referring to FIG. 9, the centrifugal pump 129 includes an impeller 14 having a plurality of vanes 146 mounted on a hub 147 adjacent to a central flow diverter 148.
5 is provided. The impeller 145 includes a magnet tray 149 holding the permanent magnets 150.
Mounted on top. Blood inflow through blood inlet port 132 is impeller 1
It experiences an increase in pressure and radial velocity caused by the rotation of 45 and exits the compartment 128 via passage 130, where blood is directed to the central void 131 of the fiber bundle 127. Centrifugal pump 129
Is magnetically coupled to a corresponding permanent magnet or electromagnet in the motor drive 121a so that the impeller 145 can be rotated at the desired angular velocity to provide the selected pumping heat and flow rate.

8A, 10 and 11A-11C, when the fiber bundle 127 is driven by the motor drive 121b, as described below, for rotation at the desired angular velocity, the compartment 126 Mounted inside. In particular, the fiber bundle 127 comprises a plurality of hollow fiber elements arranged to surround the central void 131. The lower end of the fiber element is connected to the inlet gas manifold 156 by a potting ring 155 and communicates with the void 157. The upper end of the fiber element, on the other hand, is connected by a potting ring 158 to the gas outlet manifold 159 and communicates with the void 160. Fiber bundle 127 is located in compartment 1
Mounted at the lower end on shaft 161 and at the upper end on distribution tube 162 for rotation within 26. Shaft 161 is connected to shaft 163, which in turn rotates in bearing 164, while the distribution tube rotates in bearing 165.

Referring to FIG. 11C, the distribution tube 162 preferably comprises a stainless steel shaft having a central bore 166, a gas inlet lumen 167 and a gas outlet lumen 168. Lumens 167 and 168 are close to either end and communicate with the outside of the shaft via semi-circular notches 169a and 169b, and 170a and 170b, respectively. The distribution tube 162 is connected to the housing 1
25 so that the notch 169a communicates with the chamber 171 and
There, oxygen-rich gas is introduced through gas inlet port 134. This oxygen-rich gas flows down through gas inlet lumen 167 and exits tube 162 via notch 169b. Notch 169b communicates with cavity 172, which is described in more detail below. Fiber bundle 12
Gas evacuated to void 160 through the upper end of 7 enters tube 162 via notch 170a, passes through gas outlet lumen 168, and exits tube 162 via notch 170b. Notch 170b communicates with cavity 173,
Connect to the gas outlet port 135 in order. Centrifuge pump 12 via passage 130
Blood exiting 9 enters central void 131 of fiber bundle 127 through bore 166 of distribution tube 162.

Referring now to FIGS. 10 and 11, fiber bundle 127 includes a support structure 180 disposed in central void 131. The support structure 180 comprises an upper hub 181, a lower hub 182, a connecting rod 183 and a tapered inner member 1
84 is provided. The upper hub 181 includes an annular groove forming a cavity 172, a plurality of radially oriented passages 185, and a plurality of vertical bores (which intersect the radially oriented passages 185 (FIG. 11A). See))). The lower hub 182 also includes a plurality of vertically oriented bores 18 that communicate with the annular groove portion of the void 157 via radially oriented bores 188.
7 (see FIG. 11B). Connecting rod 183 (which is hollow)
Are mounted at their upper ends in each of the vertical bores 186 of the upper hub 181, and at the lower ends of the rods, the vertical bores 1 of the lower hub 182.
87 are mounted in each. In this manner, gas introduced into cavity 172 through notch 169b passes through bores 185 and 186 of upper hub 181, passes through connecting rod 183, passes through bores 187 and 188 of lower hub 182, and It enters the void 157 formed by the potting ring 155 and the gas inlet manifold 156.

Accordingly, the oxygen-enriched gas introduced through gas inlet port 134
57, from which the gas travels through a number of hollow fiber elements comprising fiber bundles 127. Gas exiting the void 160 through the upper end of the fiber element is passed through the notch 170 in the separation tube 162.
a into the outlet lumen 168 via a, then the notch 170b
And through the cavity 173 to the gas outlet port 135.

In accordance with the principles of the present invention, a tapered inner member is disposed within support structure 180 and central void 131 and is coupled to lower hub 182. Separation tube 162
Blood entering the central void through the bore 166 of the inner member 184 strikes the inner member 184 and is gradually positioned radially outwardly by the tapered surface of the inner member. Like the tapered portion 65a of the impeller shaft 65 of the embodiment of FIG. 4, the inner member 184 reduces the priming capacity of the device and increases the pressure in the central void (and thus reduces the generation of microbubbles). And reducing the blood damage both by gradually accelerating the blood entering the void relative to the angular velocity of the surrounding fiber bundle.

Applicants have observed whether microbubbles tend to coalesce along the axis of the central void during operation of a prototype device having a rotating fiber bundle as shown in FIG. did. Therefore, a vent tube 141 having a lower end communicating with the upper part of the central void 131 is provided, so that any bubbles that merge within the central void can be vented, thereby further reducing the risk of the bubbles being carried downstream. Let it. In addition, the vent tube 141 and vent port 140 can be used to measure blood pressure within the central void of the fiber bundle. This blood pressure may also be measured by a pressure transducer 142 attached to the vent tube 141 (see FIG. 10). This information, along with the fiber bundle rotation speed, inlet gas pressure and heat supplied by the pre-pump 129, can then be used to control microbubble formation in the compartment 126.

As in the previous embodiment, lower hub 182 is coupled to magnet tray 190 by shafts 161 and 163 and drive pin 191. Magnet tray 19
0 preferably holds a permanent magnet 193 that magnetically couples the fiber bundle to the motor drive 121b so that rotational movement is
7 is transmitted. As described hereinbelow, the centrifugal pump 129 and the fiber bundle 127 are preferably driven at different angular velocities, which are selected or regulated by the controller 122 and some of the pump / oxygenators (Minimize the generation of microbubbles).

According to a preferred aspect of the present invention, the rotational speed of the centrifugal pump 129 and fiber bundle 127 is selected or adjusted so that over a range of blood flow rates and for a range of gas inlet pressures, Pump / oxygenator 12
The oxygenation level of the blood passing through zero can be optimized, limiting microbubble formation and associated blood damage. Thus, for example, the microprocessor 123 of the controller 122 is programmed with an appropriate empirically derived algorithm for the gas inlet pressure and the rotational speed of the pre-pump and fiber bundle, and as described below, Obtain at least a minimum value of the oxygen supply: H _pre-pump = f ₁ (ω ₁ ) (1) _FE = f ₂ (ω ₁ , ω ₂ ) (2) O ₂ = f ₃ ( _FE , ω ₁ , ω ₂ , Ρ _I , Ρ _O ) (3) B _gen = f ₄ (H _pre-pump , O ₂ , T _I , T _O ) (4) where H _pre-pump is generated by the backup pump 129. F ₁ () is an empirically derived function describing the correlation between the centrifugal pump rotation speed ω ₁ and the pressure head of the backup pump for a given dimension of the pump / oxygenator 120. F _E is the blood outlet port 13 F ₂ () is an empirically derived function describing the correlation between centrifugal pump rotation speed ω ₁ , fiber bundle rotation speed ω ₂ , and blood flow speed; O ₂ is an oxygen feed rate of blood leaving the blood outlet port 133; f ₃ (), the flow rate at the blood outlet port F _E, centrifugal pump rotational speed omega _1, the fiber bundle rotational speed omega ₂ and the gas inlet pressure [rho _I And an empirically derived function describing the correlation between each of the gas outlet pressures Ρ _O ; B _gen is the microbubble generation rate; and f ₄ () is the microbubble generation Speed, pre-pump pressure head, oxygen supply level,
If necessary, coil 13 at water inlet port 137 and water outlet port 138
6 is an empirically derived function that describes the correlation between the temperature of the fluid circulated through 6;
One or more variables are kept constant and the remaining variables are varied over a range)
By executing the functions f ₁ (), f ₂ (), f ₃ () and f ₄ (
) Can be easily determined. The resulting curve is generated using multivariate processing techniques well known in the art, and may interpolate or extrapolate the behavior of the pump 120 for a given set of outputs. To minimize blood damage, a local optimum for maximizing the oxygen supply level at the minimum fiber bundle speed may be determined. Other analyzes may be advantageously performed to optimize the performance of device 120.

Accordingly, the controller 122 may be programmed using an algorithm determined as described hereinabove, such that a predetermined desired blood flow rate and oxygen supply at the blood outlet port 133 are provided. For the level, the rotational speed of the pre-pump and fiber bundle is optimized to reduce blood damage and microbubble generation. Alternatively, such as minimizing the centrifugal load on the fiber elements of the fiber bundle 127 by constantly rotating the fiber bundle at the lowest rotational speed allowed to achieve the desired blood flow rate and oxygenation level. Other optimization strategies can be advantageously employed.

In a preferred embodiment, a pressure sensor 142 (see FIG. 10) is coupled to controller 122 and provides a signal corresponding to blood pressure in central void 131. The signal output by the sensor is used by the controller 122 to select or adjust the speed of the drive motors 121a and 121b,
Ensures that the blood pressure in the central void is maintained at a level higher than the level at which significant microbubble generation is detected.

Referring now to FIG. 12, an internal assembly 200 of another alternative embodiment of the pump / oxygenator of the present invention is described. The assembly 200 comprises a fiber bundle 2 having an inlet gas manifold 202 and an outlet gas manifold 203.
And shaft seals 206a and 206 with bearings 205 as previously described herein with respect to the embodiments of FIGS.
b. However, the assembly 200 is fixedly attached to the fiber bundle, and the rotating vane 2
07 is further provided. Vane 207 is provided to increase the pressure head generated by the pump / oxygen generator. In particular, the blood release fiber bundle 20
1 hits vane 207 and is further accelerated as it exits the pump / oxygenator. As will be apparent, this housing must be modified to accommodate the vane 207, while providing the desired degree of additional pressure head and minimizing blood damage. The number, orientation and shape of the vanes 207 can be selected.

The integrated blood pump / oxygenator of the present invention has been illustratively described as employing a magnetic coupling. However, the invention can be easily adapted for use with other drive systems. For example, the magnet tray may be directly replaced with a motor drive, or may be connected by a cable to a drive system and control console located outside the sterile area. Such a direct drive system can be miniaturized to be contained within a sterile area. Further, the controls can be remotely operated using infrared or other such remote control means. The integrated blood pump / oxygenator of the present invention can also be incorporated into a standard cardiopulmonary bypass system with other standard components such as heat exchangers, venous reservoirs, arterial filters, surgical suction, cardiac foramen, and the like.

The preferred exemplary embodiments of the present invention have been described above, and various changes and modifications may be made in the present invention without departing from the invention, and as such fall within the true spirit and scope of the invention. It is intended in the appended claims to cover all such changes and modifications.

[Brief description of the drawings]

Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the above detailed description of the preferred embodiments, in which:

FIG. 1 is a perspective view of a previously known integrated blood oxygenator and pump system.

FIG. 2 is a cross-sectional side view of the pump / oxygenator of FIG.

FIG. 3 is a schematic diagram of an integrated blood oxygenator / pump constructed in accordance with the present invention.

4A and 4B are a cross-sectional side view and a cutaway interior view of the pump / oxygenator of FIG. 3, respectively.

5A to 5D are perspective views of internal components of the pump / oxygenator of FIG. 3;

FIG. 6 is a partial perspective view of an alternative embodiment of a shaft suitable for use in the pump / oxygenator of the present invention.

FIG. 7 is a partial perspective view of a further alternative embodiment of a shaft and impeller arrangement suitable for use with the present invention.

8A and 8B are an external perspective view and a partial cross-sectional view, respectively, depicting a pump / oxygenator implementing the pre-acceleration vane of FIG. 7 as a separate pre-pump element.

FIG. 9 is a side sectional view of a pre-pump element of the pump / oxygenator of FIG.

FIG. 10 is a side cross-sectional view of the pump / oxygenator component of the device of FIG.

FIGS. 11A, 11B, and 11C each show 11 boxed in FIG.
FIG. 11B is a detailed view of portions A and 11B, and a perspective view of the segmented gas pipe of FIG.

FIG. 12 is a partial view of a further alternative embodiment of an internal assembly suitable for use with the pump / oxygenator of the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (31) Priority claim number 09 / 223,685 (32) Priority date December 30, 1998 (December 30, 1998) (33) Priority claim country United States (US) ( 81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, R, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI SK, SL, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Duri, Jean-Pierre United States California 94086, Sunnyvale, W .; Iowa Avenue 1171 (72) Inventor Raynob, Alex United States of America 94596, Walnut Creek, Banders Rice Court No. 10 2101 (72) Inventor Makalwitz Anthony United States of America 94508, Dublin, Cottonwood Circle Number A 6518 (72) Inventor Piprani, Alec A. United States California 94040, Mountain View, Del Medio Avenue Number 219 141 (72) Inventor Potts, Greg United States California 94040, Mountain View, Del Medio Avenue Number 207 250 F-Term (Reference) 4C077 AA03 AA11 BB06 CC03 DD01 DD08 EE01 LL05 PP02

Claims (45)

[Claims] Claims: 1. A system for processing blood, the system comprising: a housing having a gas inlet, a gas outlet, a blood inlet, and a blood outlet; arranged for rotation in the housing. A fiber bundle, wherein the fiber bundle has a central void in fluid communication with the blood inlet; and an internal member disposed within the central void, wherein the internal member is disposed with respect to the housing. A system that is rotatable and rotatable. 2. The apparatus of claim 1, wherein said inner member has at least one vane mounted on said inner member. 3. The device of claim 1, further comprising a pumping element that accelerates the blood and delivers the blood from the blood inlet to the central void. 4. The apparatus according to claim 3, wherein said pumping element comprises a plurality of vanes. 5. The apparatus of claim 4, wherein the plurality of vanes rotate at a different angular velocity than the fiber bundle. 6. The apparatus of claim 1, wherein the inner member has a major axis and is tapered along the major axis. 7. The apparatus of claim 1, further comprising a girdle disposed around an outer surface of the fiber bundle. 8. The apparatus of claim 1, wherein the fiber bundle comprises multiple layers of a hollow fiber mat, and wherein the apparatus comprises an adhesive material inserted into the multiple layers. 9. The apparatus of claim 9, further comprising a gas manifold coupled to the fiber bundle, and a baffle plate disposed within the gas manifold and adapted to propel blood away from an external end of the fiber bundle. Item 10. The apparatus according to Item 1. 10. The internal member is connected to the fiber bundle.
The device according to claim 1. 11. The apparatus of claim 3, wherein the housing enters a first compartment containing the fiber bundle, a second compartment containing the pumping element, and the central void of the fiber bundle. A passage for directing blood exiting the first compartment for
apparatus. 12. The apparatus of claim 1, further comprising a port in communication with the central void and adapted to allow venting of gas collected in the central void. 13. The apparatus according to claim 1, further comprising a controller for controlling a rotation speed of the fiber bundle and the pumping element. 14. The device according to claim 13, wherein the device further comprises a pressure sensor that provides an output signal corresponding to blood pressure in the central void, and wherein the controller comprises: An apparatus programmed to control a rotational speed of the pumping element corresponding to an output signal. 15. The controller of claim 1, wherein the controller is also programmed to control a rotational speed of the gas transfer element corresponding to the output signal.
An apparatus according to claim 4. 16. The controller of claim 14, wherein the controller is programmed to control a degree of rotational speed of the pumping element and maintains a blood pressure at a level higher than a predetermined level within the central void. Equipment. 17. The apparatus of claim 14, wherein the controller adjusts a rotational speed of the gas transfer element and the pumping element at the blood outlet in response to a flow rate selected by a user. 18. The method according to claim 18, further comprising a heat exchanger disposed in the housing.
The device according to claim 1. 19. The apparatus of claim 18, wherein said heat exchanger comprises a coiled tube disposed around said fiber bundle. 20. A device for processing blood, the device comprising: a housing having a gas inlet, a gas outlet, a blood inlet, and a blood outlet; a first end, a second end, and a center. A gas transfer element having a void, wherein the first end communicates with the gas inlet and the second end communicates with the gas outlet, wherein the gas transfer element is rotatably mounted within the housing. A gas transfer element mounted; and a pumping element mounted for rotation within the housing at a speed different than a rotational speed of the gas transfer element, the pumping element being adapted to move from the blood inlet through the blood inlet. A device comprising: a pumping element that pumps the blood into the central void of a gas transfer element. 21. The device according to claim 20, wherein the device further comprises an inner member disposed within the central void, wherein the inner member extends from the first end of the gas transfer element. The device, wherein the second end is tapered. 22. The device according to claim 21, wherein the internal member comprises:
A device coupled to the gas transfer element and rotated at the same angular velocity as the gas transfer element. 23. The device of claim 20, further comprising a port in communication with the central void and adapted to allow venting of gas collected in the central void. 24. The device of claim 20, further comprising a controller that controls a rotational speed of the gas transfer element and the pumping element. 25. The device according to claim 24, wherein the device further comprises a pressure sensor that provides an output signal corresponding to blood pressure in the central void, and wherein the controller comprises: A device programmed to control the rotational speed of the pumping element in response to an output signal. 26. The controller of claim 2, wherein the controller is also programmed to control a rotational speed of the gas transfer element corresponding to the output signal.
6. The device according to 5. 27. The controller of claim 25, wherein the controller is programmed to control a degree of rotational speed of the pumping element to maintain a blood pressure at a level higher than a predetermined level within the central void. Devices. 28. The device of claim 24, wherein the controller adjusts a rotational speed of the gas transfer element and the pumping element at the blood outlet in response to a flow rate selected by a user. 29. The device according to claim 20, wherein the housing has a first compartment containing the gas transfer element, a second compartment containing the pumping element, and the central void of the gas transfer element. A device comprising a passage for directing blood to exit the first compartment to enter. 30. The device of claim 29, further comprising a heat exchanger located in the first compartment and around the gas transfer element. 31. A method for processing blood, the method comprising: providing a device comprising a housing, the housing comprising:
A gas inlet; a gas outlet; a blood inlet; a blood outlet; a gas transfer element arranged for rotation within the housing, the gas transfer element comprising a first end, a second end, a central void, and the gas transfer element. A gas transfer element having an inner member disposed within a central void, the first end connected to the gas inlet, and the second end connected to the gas inlet;
Flowing the blood into the housing such that blood enters the central void; delivering an oxygen-containing gas to the gas transfer element to remove at least oxygen from the gas transfer element; Transferring the blood through the device to the blood; rotating the inner member to flow blood out of the central void toward the gas transfer element; and providing oxygen to the blood flowing through the housing. Rotating the gas transfer element to do so. 32. The method of claim 31, wherein rotating the inner member comprises rotating the inner member at an angular velocity equal to the angular velocity of the gas moving element. 33. The method according to claim 31, wherein rotating the inner member comprises rotating the inner member at an angular velocity different from the angular velocity of the gas moving element. 34. The method according to claim 33, comprising matching the angular velocity of the inner member with the angular velocity of the gas transfer element as a function of a desired blood flow rate at the blood outlet. Including, methods. 35. The method according to claim 33, wherein the method adjusts the angular velocity of the inner member with the angular velocity of the gas transfer element as a function of a desired oxygenation level of blood at the blood outlet. The method further comprising the step of: 36. The method of claim 31, wherein the step of providing a device includes the step of the inner member having a first end and a second end and from the first end to the second end. Providing a tapered, device. 37. The method of claim 31, wherein providing a device comprises the step of providing a gas transfer element comprising a plurality of fibers and means for reducing outward bowing of the fibers. Providing a method. 38. The method of claim 31, wherein providing a device comprises providing a device having a heat exchanger disposed about the gas transfer element, and providing the device with a heat exchanger. Rotating the gas transfer element to propel blood radially outwardly therethrough. 39. The method of claim 31, further comprising venting gas collected in said central void. 40. The method according to claim 31, wherein the device further comprises a pumping element positioned to receive the blood from the blood inlet before entering the central void, the method comprising: Rotating the pumping element to accelerate and deliver the blood toward the central void. 41. The method of claim 40, further comprising controlling a rotational speed of said gas transfer element and said pumping element. 42. The method of claim 41, wherein the device further comprises a pressure sensor that provides an output signal responsive to blood pressure in the central void, the method further comprising: Measuring the blood pressure in the pump; and controlling the rotational speed of the pumping element in response to the output signal. 43. The method of claim 42, further comprising controlling a rotational speed for said gas transfer in response to said output signal. 44. The method according to claim 42, wherein the method comprises adjusting the rotational speed of the pumping element to maintain blood pressure at a higher level in the central void than a predetermined level. 5. The method of claim 4, further comprising the step of controlling.
3. The method according to 2. 45. The method according to claim 41, wherein the method adjusts the rotational speed of the gas transfer element and the pumping element at the blood outlet in response to a flow rate selected by a user. A method comprising the steps of: