Patent Description:
Many types of blood pump-oxygenator systems are well known in the art. For example, during open-heart surgery, the patient is interconnected with an external pump-oxygenator system, commonly known as a heart-lung machine, which circulates blood and introduces oxygen into the blood system. Most types of pumps employ a roller or a centrifugal pump to flow blood in the patient's vascular system. Most types of oxygenators also use a gas-permeable membrane, wherein blood flows along one side of the membrane and oxygen is supplied to the other side of the membrane. Given a sufficient pressure gradient between the oxygen supply and the blood, the oxygen will diffuse through the membrane and into the blood. In addition, carbon dioxide will tend to diffuse from the blood into the membrane.

Typical cardiopulmonary bypass systems are rather complex, and generally are not particularly well adapted for applications longer than <NUM> hours. Moreover, most standard systems exhibit poor hemodynamic characteristics. That is, such systems typically cause too much damage to the blood to be useful for extended periods.

For example, typical cardiopulmonary bypass systems are disclosed in <CIT>, <CIT>, and <CIT>. Such conventional systems commonly utilize several pumps, a venous reservoir, an arterial reservoir, and a separate bubble-trapping device. These conventional systems exhibit several disadvantages. The most apparent disadvantage is the overall complexity of such systems. For example, the pumps may need to be synchronized with each other, or each of the reservoirs or bubble traps may need a special support frame. Also, the numerous components require extensive tubing and interconnections. Document <CIT> discloses the preamble of independent claim <NUM>.

The complexity of the conventional systems leads to higher costs of manufacture and operation. Also, the more complex systems may take longer to set up, and system set-up may require expert personnel and supervision. Even with such expert personnel present, the system's complexity increases the risk of error in setting up the system. Likewise, once in operation, a conventional system requires continuous monitoring and adjustment by expert personnel.

Conventional cardiopulmonary bypass systems are also not usable for long-term application because they significantly damage the blood after a fairly short use (e.g., <NUM>-<NUM> hours). For instance, conventional occlusive roller pumps mechanically destroy red blood cells. This "blood trauma" can occur in any cardiopulmonary bypass system. It is caused and/or aggravated by occlusive pumps, interconnections and other system components likely to increase system pressure or turbulence. Similarly, conventional oxygenators beyond few hours to a day result in diminished performance due to plasma leakage into the hollow fibers.

The above factors illustrate the need for and desirability of a simple cardiopulmonary bypass system with relatively few components. Devices similar to that disclosed in <CIT> represent attempts to achieve such simplicity. Litzie et al. disclose an emergency bypass system with one non-occlusive pump, an oxygenator, and a separate bubble trap. Litzie et al. describes a centrifugal rotor-type pump connected proximal to (i.e., on the venous side of) the oxygenator. While Litzie et al. represents a simplified cardiopulmonary bypass system compared to other known systems, it still requires the bubble-trapping device in addition to the pump and oxygenator.

In other situations, a smaller, implantable oxygenator may be sufficient to adequately supplement the patient's cardiopulmonary function by marginally increasing the oxygen content of the patient's blood. For example, patients suffering from emphysema, pneumonia, congestive heart failure, or other chronic lung disease often have blood oxygen partial pressures of approximately <NUM> torr. A relatively small increase of <NUM>% to <NUM>% is generally sufficient to adequately maintain the patient. This is a particularly desirable alternative in that it avoids the need to intubate the patient in such cases. In addition, temporary use of this type of oxygenator is sufficient in many cases to tide the patient over an acute respiratory insult. Placing such patients on a conventional respirator is often the beginning of a progressive downhill spiral by damaging the patient's pulmonary tree and thereby causing greater dependence on the respirator.

A number of devices and processes have been invented in the past incorporating this basic technology, including the following:.

The Bodell patent demonstrates the general concept of using gas permeable fibers to boost the oxygen level of blood. In the implantable embodiment of the Bodell device, a tubular casing serves as a shunt either from the pulmonary artery to the left atrium of the heart, or more generally between an artery and a vein. A multitude of parallel-connected capillary tubes are used to oxygenate and/or purify the blood circulating through the casing.

The Mortensen patent shows a transvenous oxygenator made of a plurality of small diameter gas permeable tubes. However, the specific device disclosed by Mortensen has a significant disadvantage in that two incisions are required. The insertion process is also rather complex.

The Taheri patent discloses a transvenous oxygenator having a single membrane through which oxygen diffuses. The membrane is disposed within a sheath and a flexible wire supports both.

A need exists for a circulatory support system capable of supporting a patient in circulatory dysfunction for some length of time. Such a circulatory support system would be quite useful in numerous situations, such as (<NUM>) where the patient is in a state of cardiogenic shock; (<NUM>) where the patient is in a state of septic shock, (<NUM>) for post cardiotomy weaning from the bypass, (<NUM>) for assisting the circulatory system to avoid an impending myocardial infarction; and (<NUM>) bridge-to-transplant patients. It is highly desirable to simplify the system as much as possible.

The present invention is directed at addressing this need and eliminating, or at least reducing the effects of, the shortcomings of the prior art systems as described above.

The present invention provides a greatly simplified cardiopulmonary bypass system. The system of the present invention can be implemented using only two basic components (a pump and an oxygenator), without the need for a specialist to setup and maintain the system, the requisite tubes, connectors, and cannulations. The components are connected as a closed series circuit adapted for extracorporeal processing of the patient's blood.

A blood pump-oxygenator system according to the invention is defined in independent claim <NUM>.

To eliminate the need for separate reservoirs, the pump-oxygenator system of the present invention may be provided with pressure feedback system to control the pump suction force. In this regard, the system of the present invention is a relatively static-volume system as compared to conventional systems, which normally include one or more separate reservoirs or the like. The pump-oxygenator system may be equipped with a gas heater and thermal insulation so as to eliminate the need for a heat exchanger to maintain fluid temperature. The reduced size of the system and the reduced dwell time of the blood outside the patient's body also eliminate the need for a heat exchange system.

To eliminate the need for a separate bubble trap, negative pressure is used to circulate gas in the oxygenator. The pump-oxygenator may be positioned such that the fluid may flow through the oxygenator to the inlet of the pump by gravity, or by gravity in combination with the patient's venous pressure. This orientation further enables a smooth and low-pressure fluid flow through the system, further reducing blood trauma.

The pump/oxygenator of the present invention allows for the replacement of the pump and oxygenator without the need to replace the entire system. In other words, according to the invention, the pump and oxygenator are modular components that may be replaced without the need to interrupt the system operation or the need to re-prime the circuit. The pump and/or oxygenator may be mounted on a catheter, with one catheter used to remove the pump and/or oxygenator and the another inserted in its place so as to replace the pump and/or oxygenator without the need to interrupt the system operation. This feature allows the replacement of components that are not intended for long-term operation to render the system applicable for long-term use even though its components may only be adequate for short-term use only.

The system of the present invention can provide partial veno-arterial cardiopulmonary support over a relatively long period (i.e., one to ten days) because of its very low overall blood trauma and improved ease of use characteristics. The system is capable not only of providing cardiopulmonary support but also of providing hemodynamic support over a potentially long period. The system of the present invention is particularly adapted for partial hemodynamic support. Notwithstanding this, it is to be readily appreciated that the system is also suitable for achieving a number of additional objectives in a variety of situations involving circulatory dysfunction. The system of the present invention can assist circulation during relatively mild circulatory dysfunction, and also can provide acute assistance during severe refractory cardiac failure caused by myocardial infarction, cardiomyopathy, or post-cardiac surgery. The system of the present invention may also be useful in providing perioperative support and stabilization of high-risk patients, such as coronary bypass surgery patients.

The low-trauma of the present invention contributes desirable overall hemodynamic characteristics. Many of the features of the present invention that improve the overall hemodynamics of the system also help to simplify the system, and to make it more reliable and compact.

The small number of system components also enables easier set-up and operation, and reduces the risk of system malfunction. To further reduce the risk of system malfunction, the system may be equipped with various fail-safe features. Such equipment may be used to monitor and control various pressures and flow rates to ensure proper operation. Although the system of the present invention may require periodic monitoring and adjustment by expert personnel during operation, it is relatively automatic. That is, compared to conventional systems, which tend to be more complex, the system of the present invention requires much less monitoring and adjustment during operation.

The system of the present invention also causes less damage to the blood than conventional systems by reducing the surface area the blood interacts with, making the system of the present invention more suitable for long-term applications. Trauma to the patient's blood is reduced principally by the simplicity of the blood circuit, especially the low number of circuit elements, the non-occlusive pump and the design of the oxygenator. In addition, overall trauma to the patient is reduced. This is accomplished by reducing the extracorporeal processing of the blood as compared to conventional bypass systems and procedures. The absence of separate fluid reservoirs reduces the fluid volume of the system of the present invention. Because less of the patient's blood is withdrawn from the body at one time, the overall trauma to the patient is reduced.

The possibility of swapping oxygenators without the need to stop the system increases the usefulness of the system for long-term applications. Oxygenators in general degrade in function very rapidly over time, therefore, the possibility to change oxygenators without interrupting patient support increase the overall lifetime of the system.

The other main difference between the present invention and the prior art is that the present invention passes the blood over the oxygenator multiple times, thereby providing the same level of oxygenation and allowing the size of the oxygenator to be greatly reduced in size relative to the "single pass" prior art oxygenators. The "multiple pass" feature of the present invention is also advantageous in that it serves to provide a heat exchanger functionality as well as air entrapment.

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

In accordance with the preferred embodiment of the present invention (with particular attention to <FIG>), an extracorporeal system is provided comprising a pump <NUM>, an oxygenator <NUM>, an inflow cannula <NUM>, and an outflow cannula <NUM>. Among the inventive aspects to be described in detail herein, the extracorporeal system of the present invention boasts a miniaturized pump <NUM> and oxygenator <NUM> and a simplified circuit to allow ease of use and reduce trauma to patients by reducing the extent to which blood interacts with foreign surfaces. Cannulas <NUM>, <NUM> may be any suitable cannula of known construction for use in transporting blood. Cannulas <NUM>, <NUM> may be made from any suitable biocompatible material, including but not limited to urethane or silicone or similar biocompatible material. Cannulas <NUM>, <NUM> may be reinforced with metallic wire or similar material to help the cannula resist kinking when bent in a sharp radius. All these details are well known in the cannula manufacturing industry and are included here for clarity.

Referring to <FIG>, the pump <NUM> may be provided (by way of example only) as a rotary or a displacement pump and, more specifically, a rotary pump of the centrifugal type. Centrifugal pumps are a known art in the blood pumping area and are preferred due to the low cost of manufacturing and the low trauma to the blood. Blood pump <NUM> may be directly driven by an electric motor or driven by a flexible cable that links the pump to the electric motor (as described, for example, in <CIT>). The coupling between the pump and the driving mechanics may be magnetically or directly coupled. Pump <NUM> is shown of the axial flow type with rotor <NUM> situated inside pump housing <NUM>, with drive cable <NUM> inside sheath <NUM> coupled to rotor <NUM>. The rotation of cable <NUM>, by an electric motor (not shown), causes the rotation of rotor <NUM> and the pumping of fluid from the distal end to the proximal end of housing <NUM>. In this fashion, fluid is transported from inflow cannula <NUM> toward outflow cannula <NUM>.

According to one aspect of the present invention, manifold <NUM> may be provided with at least one manifold port <NUM> capable of passing devices or instruments therethrough for placement inside manifold <NUM>. Suitable hemostasis valves <NUM> may be required to ensure hemostasis during and after such placement. Manifold <NUM> may be also be equipped with a quick-connect coupling <NUM> to facilitate the connection and disconnection of inflow cannula <NUM> or outflow cannula <NUM>, as well as other components, in their perspective location in the circuit. Quick-connect coupling <NUM> may be provided, by way of example only, as a two-component system intended to quickly join or release two tubes, or modules, quickly and insure a fluid tight connection.

As shown in <FIG>, the pump <NUM> may be placed inside manifold <NUM> by passing it through one manifold side port <NUM>. In this instance, hemostasis valve <NUM> will close around sheath <NUM>, providing hemostasis after pump <NUM> is placed therethrough. In similar fashion, oxygenator <NUM> may be placed inside manifold <NUM> through manifold port <NUM>' with hemostasis valve <NUM>' forming a seal around oxygenator sheath <NUM>. Sheath <NUM> preferably consists of at least two lumens (shown in <FIG>), inflow lumen <NUM> for oxygen delivery to oxygenator fiber <NUM> and outflow lumen <NUM> for the removal of oxygen (O<NUM> gas) and carbon dioxide (CO<NUM> gas) from oxygenator fiber <NUM>. Oxygenator <NUM> consists of oxygenation fibers <NUM> that allow for blood to pass between oxygenator fibers <NUM> to intake oxygen and release CO<NUM> gas. In return, oxygen is passed through the inside lumen of oxygenator fibers <NUM> from inflow lumen <NUM> at one end of oxygenator fibers <NUM> and returned from the other end of oxygenator fibers <NUM> to lumen <NUM> of sheath <NUM> for release into the atmosphere. Oxygenator <NUM> is matched in size to the inside diameter of manifold <NUM> to allow a close fit in order to limit blood flow around oxygenator <NUM> and force the blood to flow through oxygenator fibers <NUM> and maximize blood oxygen and CO<NUM> exchange.

One main advantage of this invention is the capability to replace pump <NUM> or oxygenator <NUM> with another pump or oxygenator in case pump <NUM> or oxygenator <NUM> became defective or less efficient over time. A main draw back of most oxygenators is the continuous reduction in gas exchange capability the longer it is used due to fiber deterioration. This invention would allow the replacement of oxygenator <NUM> when its performance deteriorates and, importantly, will allow such replacement without the need to stop the pump or the need to prime the circuit again.

With reference to <FIG>, shown is a pump-oxygenator system according to a further embodiment of the present invention. Manifold <NUM> consists of main trunk <NUM> and side trunk <NUM> that connects the distal end of main trunk <NUM> with the proximal end of main trunk <NUM>. Pump <NUM> is placed through manifold side port <NUM> and advanced into main trunk <NUM> downstream from side trunk <NUM> junction with main trunk <NUM>. Oxygenator <NUM> is placed through manifold side port <NUM>' and advanced through portion of manifold side trunk <NUM>. Hemostasis valves <NUM> and <NUM>' form a tight seal around sheath <NUM> and <NUM> respectively. Balloon catheter <NUM> is placed trough manifold side port <NUM>", which is located at side trunk distal end <NUM> such that hemostasis valve <NUM>" seals around ballooned catheter shaft <NUM>. Occluding balloon <NUM> is attached to the distal end of ballooned catheter shaft <NUM> and placed in side trunk distal end <NUM> but does not reach main trunk proximal end <NUM>. Inflating occluding balloon <NUM>, by infusing fluid (preferably saline), will partially or fully occlude manifold side trunk <NUM> and will limit the amount of blood that circulates through manifold side trunk <NUM>. In essence, occluding balloon <NUM> sets the portion of blood flowing through manifold side branch <NUM> and the portion of blood flowing through manifold main trunk distal end <NUM> and onward to outflow cannula <NUM>. As such, the blood flow through oxygenator <NUM> or the outflow cannula <NUM> depends on the degree to which the occluding balloon <NUM> is inflated. A fully inflated occluding balloon <NUM> will cause the blood flow from pump <NUM> to go entirely through outflow cannula <NUM> (with none flowing through the oxygenator <NUM>). Conversely, a fully deflated occluding balloon <NUM> will cause the blood flow from pump <NUM> to go entirely through oxygenator <NUM> (with none flowing through outflow cannula <NUM>).

Pump <NUM> may be set to deliver a flow rate in excess of what is desired to deliver to the patient, wherein all excess flow is re-circulated through the oxygenator <NUM> such that the blood is repeatedly subject to the exchange of O<NUM> and CO<NUM> within the oxygenator <NUM>. The oxygenator <NUM> may be of substantially reduced size based on this "multiple pass" feature, wherein blood is passed multiple times over the oxygenator before being circulated to the patient. This "multiple pass" aspect of this invention simplifies the system and reduce its size and the blood volume needed to prime the circuit. Another advantage of this invention is the capability to place the circuit on the patient and therefore minimize the entire circuit complexity and size.

<FIG> illustrates yet another pump-oxygenator system according to the present invention. Manifold <NUM> includes a bubble trap <NUM> in main trunk <NUM> with blood pump <NUM> located at an inlet port <NUM> of bubble trap <NUM>. Blood pump <NUM> empties all blood into bubble trap <NUM> before blood leaves to either manifold <NUM> side trunk <NUM> or to outflow cannula <NUM> and serves to remove any air bubbles from the pumped blood. Bubble trap <NUM> includes venting port <NUM> at the top of a conical top to vent any air entrapped in bubble trap <NUM>. Inlet port <NUM> is preferably located close to the top end of bubble trap <NUM> while outlet port <NUM> is preferably located close to the bottom end. In addition, inlet port <NUM> of bubble trap <NUM> may be located to the side, rather than the center, of the main cavity <NUM> of the bubble trap <NUM> in order to enhance the formation of a vortex in the pumped blood. This will help increase the dwell time of the pumped blood in the bubble trap <NUM> and will capitalize on the centrifugal force to separate smaller air bubbles from the pumped blood. Bubble trap <NUM> may also include a screen (not shown) to trap any debris from the pumped blood. Pump <NUM>, although shown in <FIG> and <FIG> as being of axial design, may be centrifugal in design without affecting the function of this invention.

<FIG> illustrates a pump-oxygenator system of the present invention similar to that of <FIG>, except for the addition of a heat exchanger <NUM>. Heat exchanger <NUM> may preferably be a catheter system formed by a dual lumen catheter <NUM>, wherein a fluid (heated or cooled) is injected through one lumen to heat or cool heating fibers <NUM>. Heating fibers <NUM> are hollow fibers that are made of heat conducting material that are pliable and resist kinking to allow advancement into side trunk <NUM> of manifold <NUM> as shown in <FIG>. Any number of suitable materials may be employed for the heat exchanger <NUM>, including but not limited to polymeric or metallic material such as Nitinol. One end of heating fibers <NUM> are in communication with one lumen of dual lumen catheter <NUM> while the other end of heating fibers <NUM> is in communication with the other lumen of dual lumen catheter <NUM>. Therefore, pumping fluid in the first lumen of dual lumen catheter <NUM> will direct the fluid to heating fibers <NUM> first such that heat will be delivered or removed from the circulating blood before the fluid exits through the second lumen.

<FIG> illustrates a pump-oxygenator system of the present invention, wherein oxygenator <NUM> is inserted through manifold side port <NUM> into main trunk <NUM> of manifold <NUM> and advanced into oxygen compartment <NUM> of bubble trap <NUM>. Blood flowing from inflow cannula <NUM> enters through oxygen compartment <NUM> and gets deflected upwardly by deflector <NUM> before it reaches bubble trap compartment <NUM>. Bubble trap compartment <NUM> allows any air bubbles to float to the top of bubble trap <NUM> and be removed through venting port <NUM>. Deflector <NUM> and the design of bubble trap <NUM> in general may be fashioned to enhance the formation of a vortex flow at the top of bubble trap <NUM> to enhance the capability of isolating air bubbles in the top portion of bubble trap <NUM>.

Occluding balloon <NUM> may be synchronized with the heart rhythm. In particular, occluding balloon <NUM> may be fully deflated during systole (keeping the systemic pressure to a minimum to allow the heart to eject with minimal effort) and fully inflated during diastole (causing all oxygenated blood in bubble trap <NUM> to empty into the patients through outflow cannula <NUM>). In addition, bubble trap <NUM> may have a volume which matches the average patient's stroke volume or less, such that for each heart cycle the system empties oxygenated blood contained in bubble trap <NUM> before occluding balloon fully deflates and starts re-circulating non-oxygenated blood drained from the venous system through inflow cannula <NUM>. In essence, the present embodiment is designed to drain venous blood and infuse oxygenated blood during heart diastole and to re-circulate blood past the oxygenator during heart systole. This will advantageously result in the heart pumping against lower systemic pressure, which translates into a lower workload on the myocardium.

<FIG> illustrates a pump-oxygenator system of the present invention, which is substantially identical to that illustrated in <FIG>. An extra pump <NUM> is positioned at the outflow cannula <NUM> to deliver a set volume to the patient. This extra pump <NUM> may be controlled independently from the main blood pump <NUM> that circulate the blood in the oxygenator portion of the device. Therefore, the blood volume delivered to the patient could be instantaneously changed according to the patient requirements.

<FIG> represent alternative arrangements for the system components shown, by way of example only, in <FIG>. <FIG> is basically the same system depicted in more details in <FIG> with the addition of two flow meters, re-circulation flow meter <NUM> and outflow flow meter <NUM>' that measure flow rate in the respective part of the circuit. <FIG> is the same as circuit 7a with oxygenator <NUM> and heat exchanger <NUM> reversed in location in the circuit. This arrangement may beneficial in some application versus other. For example, it might be preferable to cool blood after it has passed through oxygenator <NUM>. <FIG> shows the addition of reservoir <NUM> to the system. Reservoir <NUM> may be used to store some blood volume that may be added to the circulation in case blood collection from patient becomes interrupted. Alternatively, reservoir <NUM> may be used to store excess in blood volume from the patient or may blood intended for transfusion into the patient, therefore the pump is used to introduce this extra blood. Reservoir <NUM> may be in series with inflow cannula <NUM> (not shown) instead of being in parallel (as shown in <FIG>). In this arrangement pump <NUM> will siphon blood from the reservoir (assuming the reservoir is made from soft pliable walls) instead of siphoning directly from the patient. The advantage of this arrangement is the buffering of the pump suction from acting on the patient.

In accordance with the present invention, one method of using the pump-oxygenator system described herein for (by way of example only) treating heart failure, will be described as follows:.

As noted above, the selective inflation of occluding balloon <NUM> controls the portion of blood that returns to the pump inlet and the portion of blood that flows to the patient. Blood has the preference to re-circulate to the pump inlet since it is the least resistive path for the blood flow. As such, the more the occluding balloon <NUM> is inflated, the more flow will diverted to the patient. Stated another way, occluding balloon <NUM> determines the ratio of blood returning to the pump <NUM> from the outflow cannula <NUM> versus the new blood coming from inflow cannula <NUM>. The rotational rate of the pump <NUM> determines the total volume of blood flowing through pump <NUM>. A high flow rate is typically desired since the higher the flow rate of pump <NUM> relative to outflow cannula <NUM>, the more oxygenation will take place. Similarly, the higher the re-circulating blood portion, the smaller the oxygenator <NUM> may be since the same blood will pass multiple times over oxygenator <NUM> and get a higher level of oxygenation. It may be desired at times to use a vacuum source to drive the flow of oxygen in the system rather than positive pressure. Vacuum driving will favor blood entry into the micropores of oxygenation fibers <NUM> rather than air leaving into the blood.

A significant aspect of the pump-oxygenator system of the present invention is the capability of easily replacing components without stopping the system operation of pump <NUM>, oxygenator <NUM>, heat exchanger <NUM>, and balloon catheter <NUM>. This eliminates one of the main drawbacks of prior art, which required the entire system to be stopped in order to replace even one element. This, in turn, required subsequent re-priming of the system after the replacement procedure had taken place. This "switch out" capability of the present invention is a significant improvement over the prior art in that component replacement is frequently required due to fast degradation of oxygenator elements.

<FIG> shows one manner of accomplishing the "switch out" feature of the present invention. Oxygenator <NUM>, for example, may be placed inside soft tube <NUM>, which may be made from silicone or similar soft medical tubing. The proximal end of soft tube <NUM> may be preferably equipped with venting port coupling <NUM> coupled to hemostasis valve <NUM>. The distal end of soft tube <NUM> is fitted with quick-connect fitting 103a (male), wherein quick-connect fitting 103b (female) is attached to manifold side <NUM> of manifold <NUM>. To insert oxygenator <NUM> into manifold <NUM>, clamping section <NUM> (which is made of similar material to soft tube <NUM>) is clamped using a standard tubing clamp. Quick-connect fitting 103a may then be coupled to quick-connect fitting 103b (to thereby form a unitary quick-connect coupling <NUM>). The clamp may then be removed from clamping section <NUM>, which serves to force blood into soft tube <NUM> and oxygenator <NUM>. Air may be removed from soft tube <NUM> through venting coupling <NUM> and may be augmented by tapping, massaging, knocking soft tube <NUM> to release any entrapped air in oxygenator <NUM>. After removing all entrapped air, oxygenator <NUM> may be advanced through quick-connect <NUM> and clamping section <NUM> into manifold <NUM> without interrupting system operation.

To remove oxygenator <NUM> from service or to replace it, oxygenator <NUM> may be pulled back into soft tube <NUM> by pulling the oxygenator sheath <NUM> until oxygenator <NUM> is past quick-connect <NUM>. Clamping section <NUM> may then be clamped using a standard tube clamp. At this point, quick-connect <NUM> may be separated into its quick-connect male fitting 103a and quick-connect female fitting 103b such that the existing oxygenator <NUM>, soft tube <NUM>, venting coupling <NUM>, and hemostasis valve <NUM> may be replaced by a new set. The same removal replacement method may be used for other component such as, pump <NUM>, heat exchanger <NUM>, or ballooned catheter <NUM>.

<FIG> illustrates another pump-oxygenator system according to the present invention comprising an extracorporeal system <NUM> including a base <NUM>, a lower oxygenator cartridge <NUM>, an upper oxygenator cartridge <NUM>, an integrated pump compartment <NUM>, and a sterile barrier <NUM>. As shown in <FIG>, base <NUM> comprises two cavities, namely, an upper oxygenator compartment <NUM> and a lower oxygenator compartment <NUM>, which are located on one side of base <NUM> (referred to as the "top side" herein) and shaped to receive upper oxygenator cartridge <NUM> and lower oxygenator cartridge <NUM>, respectively. Base <NUM> also includes an integrated pump (not shown), which is fully encapsulated inside the walls of base <NUM> and preferably a standard miniaturized rotary pump of the centrifugal type with an integrated electric motor encapsulated inside pump compartment <NUM> of base <NUM>. The inflow port of the integrated pump (not shown) is in direct communication with the system inflow opening <NUM> located on the opposite side (referred to as the "bottom side" herein) of lower oxygenator compartment <NUM> and adjacent to the system outflow opening <NUM>. Sterile barrier <NUM> is preferably an adhesive and/or foam base material that is disposed at the periphery of base <NUM> on the bottom side to interface with the patient skin and form a seal between the inside and outside area formed by sterile barrier <NUM>. Sterile barrier <NUM> may preferably be saturated with a concentrated antibacterial and antiviral solution that prevents the crossing of any living organism from the outside to the inside of sterile barrier <NUM>. Sterile barrier <NUM> may be made of flexible material and shaped to allow the use of suction (not shown) along its entire length to assure the adhesion between sterile barrier <NUM> and the patient skin.

As shown in <FIG>, each oxygenator cartridge (lower oxygenator cartridge <NUM> and upper oxygenator cartridge <NUM>) comprises a cartridge inflow <NUM> and a cartridge outflow <NUM> in communication with cartridge cavity <NUM>. A matrix <NUM> of hollow fibers (of the type typically used in artificial oxygenators) is layered on top of a blood filtering material, filter mesh <NUM> (of a type typically used in filtering blood during bypass surgery). Matrix <NUM> is arranged to receive oxygen mixture, into the interior lumen of the hollow fibers, through oxygen inflow port <NUM> and return oxygen and carbon dioxide to oxygen outflow port <NUM> without introducing any gas bubbles into the blood flowing on the exterior surface of the hollow fibers of matrix <NUM>. Blood will pass through filter mesh <NUM> before exiting the cartridge to capture any particles before entering the patient's blood stream. Filter mesh <NUM> may be designed to capture particles seized generally larger than <NUM> micrometers and preferably larger than <NUM> micrometers.

Oxygenator cartridges <NUM>, <NUM> may also include a heat exchange element <NUM>, which is a thermal resistor that may be heated electrically. Heat exchange element <NUM> is mainly used to heat top plate <NUM> of lower oxygenator cartridge <NUM> in the case it is desired to heat any blood going through system <NUM>. Upper oxygenator cartridge <NUM> may be similarly equipped with a heat exchange element (not shown) for the same purpose mentioned above. Alternatively, a manifold design (not shown) may be incorporated in top plate <NUM> of lower oxygenator cartridge <NUM> to allow the circulation of cooled or heated fluid in order to cool or heat blood circulating through system <NUM> if desired by the user. The cooling or heating fluid may be circulated by a miniature pump similar to standard pumps used in bypass surgery for the same purpose (not shown).

With reference to <FIG>, inflow cannula <NUM> and outflow cannula <NUM> may be are attached to a plate <NUM>. Plate <NUM> preferably comprises two barbed fittings (inflow barbed fitting <NUM> and outflow barbed fitting <NUM>) designed to receive the proximal end of inflow cannula <NUM> and outflow cannula <NUM> respectively (<FIG> shows only one cannula connection, the other connection is identical but not shown). Inflow barbed fitting <NUM> and outflow barbed fitting <NUM> may have standard barbs (not shown) used in standard medical connector used in connecting PVC tubing to a tubing connector. In addition, plate <NUM> may include inflow hemostasis valve <NUM> and outflow hemostasis valve <NUM> that seal blood inside the cannula and air outside the cannula prior to attachment of plate <NUM> to base <NUM>. Both inflow hemostasis valve <NUM> and outflow hemostasis valve <NUM> may have a central perforation or slits (not shown) so as to allow the insertion of a rigid tube (such as system inflow <NUM> and system outflow <NUM>) into inflow hemostasis valve <NUM> and outflow hemostasis valve <NUM>, respectively. Upon connection of base <NUM> to plate <NUM>, system inflow <NUM> and system outflow <NUM> engage hemostasis valve <NUM> and outflow hemostasis valve <NUM>, respectively, and allow blood to freely flow from and/or into the respective cannula <NUM>, <NUM>.

With particular reference to <FIG>, lower oxygenator cartridge <NUM> is designed to fit lower oxygenator compartment <NUM> and engage system outflow opening <NUM> by pushing cartridge outflow <NUM> through lower compartment hemostasis valve <NUM>, which functions similarly to outflow hemostasis valve <NUM>. In essence, the removal of lower oxygenator cartridge <NUM> causes the full closure of lower compartment hemostasis valve <NUM> and containment of blood inside and air outside the manifold of system <NUM>. This design allows the replacement of either oxygenator cartridge (lower oxygenator cartridge <NUM> and upper oxygenator cartridge <NUM>) without introducing any air into the system or the need to stop the system operation. Only one oxygenator cartridge <NUM>, <NUM> may be changed at a time in order to keep system <NUM> operational.

Before the insertion of a new oxygenator cartridge <NUM>, <NUM>, the respective oxygenator compartment <NUM>, <NUM> may be filled with sterile fluid (such as sterile saline) in order to remove any air in the proximity of the respective hemostasis valve <NUM>, <NUM>. This is done to eliminate the possibility of introducing air into the system during cartridge replacement. In addition, oxygenator cartridges <NUM>, <NUM> are supplied sterile to the user and may be primed by sterile fluid to remove any air prior to connection to system <NUM>. To further assure the removal of any air from oxygenator cartridges <NUM>, <NUM> prior to connection, fluid may be circulated through the oxygenator cartridge <NUM>, <NUM> while it is partially inserted into the appropriate oxygenator compartment <NUM>, <NUM> that has already been filled with fluid. This step would flush any air from the system <NUM> to the outside atmosphere prior to connecting the oxygenator cartridge <NUM>, <NUM>. A small circulating pump (not shown) may be used for this step to completely prime the oxygenator cartridge <NUM>, <NUM> before use.

<FIG> illustrates the system <NUM> mounted to a patient chest to allow free movement of the patient. A backpack (not shown) may be worn by the patient that may provide control, power, oxygen, and other functions (such as a small pump to circulate heating or cooling fluid) to system <NUM>.

Claim 1:
A blood pump-oxygenator system for increasing perfusion and oxygen level in a patient, comprising at least one blood pump (<NUM>), an oxygenator (<NUM>), an inflow cannula (<NUM>), and an outflow cannula (<NUM>), which are connected so as to form a closed series circuit to be operable as a cardiopulmonary bypass system adapted for extracorporeal processing of the patient's blood, wherein the blood pump (<NUM>) is configured to convey blood through the circuit from the patient into the inflow cannula (<NUM>), through the oxygenator (<NUM>) and out of the outflow cannula (<NUM>) back into the patient,
wherein the system further comprises a manifold (<NUM>) connected between the inflow cannula (<NUM>) and the outflow cannula (<NUM>) so that the blood passes through the manifold (<NUM>), wherein the manifold (<NUM>) accommodates the blood pump (<NUM>) and the oxygenator (<NUM>) and is designed so as to form a recirculation loop configured to recirculate at least part of the blood in the circuit such that the blood passes over the oxygenator (<NUM>) multiple times,
characterized in that the system further comprises an extra blood pump (<NUM>) positioned at the outflow cannula (<NUM>) and configured to deliver a set volume to the patient, wherein the extra pump (<NUM>) is configured to be controlled independently from the blood pump (<NUM>) that circulates the blood in the manifold (<NUM>) including the oxygenator (<NUM>), and
in that the blood pump (<NUM>) and the oxygenator (<NUM>) are modular components to allow replacement of at least one of the blood pump (<NUM>) and the oxygenator (<NUM>).