Full-eject pneumatic pump system and method

Abstract

An apparatus including a two-chamber pneumatic pump system (that has its internal volume divided, by a flexible diaphragm, into an activating chamber and an activated chamber) and methodology of operating such apparatus in a manner that does not require and, therefore, avoids overcompensation of pressure of the fluid in the activating chamber – specifically, in a manner preventing the conventionally-used setting of the maximum pressure of fluid delivered to the activating chamber to a value that exceeds that which is operationally required in order to ensure the full ejection of contents of the activated chamber.

Description

FULL-EJECT PNEUMATIC PUMP SYSTEM AND METHODCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This International Patent Application claims priority from and benefit of the US Provisional Patent Applications No. 63 / 594,097 filed on October 30, 2023, the disclosure of each of which is incorporated herein by reference.TECHNICAL FIELD

[0002] This invention is generally related to techniques for structuring and / or driving a pneumatically actuated pump system and, in particular, to an apparatus containing a pneumatic driver structured to provide pneumatic power to a pump system that has shell defining a substantially constant volume, which volume is separated by a moveable chamber separator into an activating chamber (receiving pneumatic energy from the driver) and an activated chamber receiving and releasing a fluid from and to the intended environment as a result of operation of the activating chamber.RELATED ART

[0003] General area for use of implementations of the idea of this invention is pneumatic pumps and, specifically, pneumatic pump systems that are air-driven and that include two chambers formed within an overall volume enclosed within the shell (or chamber housing). A chamber separator within the shell divides the shell into these two chambers. One of the chambers - referred to herein for simplicity as “activating chamber” - is connected to a power console that includes a pneumatic driver reversibly pushing a first fluid into the activating chamber (and thereby causing a reversible change of a position of the chamber separator within the overall volume of the shell and modifying the local volume of the other of the two chambers in a reversible manner). The other chamber - referred to herein for simplicity as “activated chamber” - is operably connected with local environment and is caused at least (i) to pull in from the local environment a second fluid when the movement of the chamber separator creates negative internal pressure in the activated chamber and (ii) pushes this second fluid to the local environment when the movement of thechamber separator creates positive internal pressure in the activated chamber, respectively through inlet and outlet fluidly cooperating this activated chamber with such local environment.Various Applications of Air-Operated Pumps.

[0004] Pneumatic pumps of the variety mentioned above are commonly referred to as “air- operated diaphragm pumps” - they use an air (or, more generally - gas or even fluid) valve that directs compressed air (gas) between two sides of the pump, back and forth - and are frequently used to transfer liquids with a broad range of viscosities as well as liquids with suspended solids. They are used in facilities of all sizes, and in a variety of different industries - from petrochemical to food and beverage, these pumps are popular and versatile. They also can handle many aggressive chemicals such as acids because they can be constructed with a wide variety body materials and diaphragms. In particular, conventional designs lend themselves to transferring highly abrasive or viscous products. See, for example, blog.craneengineering.net / how-do-air-operated-double- diaphragm-pumps-work. See also www.arozone.com / en-us / technologies / how-diaphragm-pumps- work. As general workhorse devices, such pneumatic pumps are utilized in practically every known area unrelated to the management and care of a patent, such as in:

[0005] Mining - for dewatering above and below ground sites and quarries, transferring of slurries and sludge, transferring of fuel for vehicles or heavy construction equipment;

[0006] Coatings - for transferring, dispensing and dosing paint or ink, feed pump for spray guns;

[0007] Ceramics industries- for ceramic slips, day tank transfer, filling molds;

[0008] Chemical Processing - for loading and unloading tankers, portable utility pump, batching or dosing chemicals;

[0009] Electroplating and Anodizing - for replenishing chemicals in plating or metal finishing tanks, agitation of cleaning solutions, filtration;

[0010] Pulp and Paper industries - for printing inks, glues, bulk adhesive transfer;

[0011] Oil and Gas industries - for filter press, bulk fuel transfer, settling pond transfer;

[0012] Water and Wastewater Treatment - for transferring suspended solid media, filter press, utility pump, to name just a few.

[0013] At the same time, pneumatic pumps of the air-operated diaphragm version have also been employed in one rather specific - but not limiting in any shape or form - application related to an artificial heart system. To this end, the reader may benefit from some excursion into the structure and mechanics of operation of the heart muscle and related solutions - which are touched upon below.

[0014] The heart is the muscle that drives the cardiovascular system in living beings. Acting as a pump, the heart moves blood throughout the body to provide oxygen, nutrients, hormones, and to remove waste products. The blood follows two separate pathways in the human body, the so-called pulmonary and systemic circulatory circuits. In the pulmonary circuit, the heart pumps blood first to the lungs to release carbon dioxide and bind oxygen, and then back to the heart. Thus, oxygenated blood is constantly being supplied to the heart. Tn the systemic circuit, the longer of the two, the heart pumps oxygenated blood through the rest of the body to supply oxygen and remove carbon dioxide, the byproduct of metabolic functions carried out throughout the body. The heart supplies blood to the two circuits with pulses generated by the orderly muscular contraction of its walls.

[0015] In order to keep blood moving through these two separate circulatory circuits, the human heart has four distinct chambers that work in pairs. As illustrated in FIG. 1, the heart 100 includes a right atrium 112, aright ventricle 114, a left atrium 116, and a left ventricle 118. One pair of chambers, the right ventricle and left atrium, is connected directly to the pulmonary circuit. In it, de-oxygenated blood from the body is pumped from the right ventricle 114 to the lungs, where it is oxygenated, and then back to the left atrium 116.

[0016] In the systemic circuit, the other pair of chambers pumps the oxygenated blood through body organs, tissues, and bones. The blood moves from the left atrium 116, where it flows from the lungs, to the left ventricle 118, which in turn pumps the blood throughout the body and all the way back to the right atrium 112. The blood then moves to the right ventricle 114 where the cycle is repeated. In each circuit, the blood enters the heart through an atrium and leaves the heart through a ventricle.

[0017] Thus, the ventricles 114, 118 are essentially two separate pumps that work together to move the blood through the two circulatory circuits. Four check valves control the flow of bloodwithin the heart and prevent flow in the wrong direction. A tricuspid valve 120 controls the blood flowing from the right atrium 112 into the right ventricle 114. Similarly, a bicuspid valve 122 controls the blood flowing from the left atrium 116 into the left ventricle 118.

[0018] Two semilunar valves (pulmonary 124 and aortic 126) control the blood flow leaving the heart toward the pulmonary and systemic circuits, respectively. Thus, in each complete cycle, the blood is pumped by the right ventricle 114 through the pulmonary semilunar valve 124 to the lungs and back to the left atrium 116. The blood then flows through the bicuspid valve 122 to the left ventricle 118, which in turn pumps it through the aortic semilunar valve 126 throughout the body and back to the right atrium 112. Finally, the blood flows back to the right ventricle 114 through the tricuspid valve 120 and the cycle is repeated. When the heart muscle squeezes each ventricle, it acts as apump that exerts pressure on the blood, thereby pushing it out of the heart and through the body. The blood pressure, an indicator of heart function, is measured when the heart muscle contracts as well as when it relaxes. The so-called systolic pressure is the maximum pressure exerted by the blood on the arterial walls when the left ventricle of the heart contracts forcing blood through the arteries in the systemic circulatory circuit. The so- called diastolic pressure is the lowest pressure on the blood vessel walls when the left ventricle relaxes and refills with blood. Healthy blood pressure is considered to be about 120 millimeters of mercury systolic and 80 millimeters of mercury diastolic (usually presented as 120 / 80).

[0019] Inasmuch as the function of the circulatory system is to service the biological needs of all body tissues (i.e., to transport nutrients to the tissues, transport waste products away, distribute hormones from one part of the body to another, and, in general, to maintain an appropriate environment for optimal function and survival of tissue cells), the rate at which blood is circulated by the heart is a critical aspect of its function. The human body has a built- in mechanism (the so-called Frank- Starling mechanism) that allows it to increase the filling pressure at the heart automatically based on the oxygen requirements of the body. This, coupled with the autonomic increase in heart rate and ejection fraction, allows the circulatory system to deliver blood at a rate necessary to meet the persons’ need. Such flow rate is known as ‘cardiac output’. The cardiac output in a healthy human body may vary from about 4 toabout 15 liters per minute (LPM), according to the activity being undertaken by the person, ata heart rate that can vary from about 50 to about 180 beats per minute.

[0020] Several artificial devices have been developed over the years to supplement or replace the function of a failing heart in patients. These include devices developed by companies as well as research institutions such as the Berlin Heart Institute, the Pennsylvania State University, the University of Utah, the Cleveland Clinic Foundation, the University of Perkinje (in Bruno, Czechoslovakia), the University of Tokyo, the Thoratec Corporation, Abiomed Inc., Novacor, and Symbion Inc. Typically, these artificial devices include pumps that aim at duplicating the required pumping functions of the left and right human ventricles. One method of actuation for these pumps has been through the pneumatic action of an external mechanism. See, for example, U.S. Patents Nos. 4,611,578 and 5,766,207. Periodic pulses of compressed air drive the pumps at the desired pressure and rate of cardiac output. A moderate vacuum may be applied between pulses to allow more rapid refilling of the ventricles with blood flowing from the respective atrium.

[0021] (As an aside, one notable air-actuated diaphragm pump configured as an artificial heart system is currently in use as an implant for patients waiting for a heart transplant is the Total Artificial Heart manufactured by SynCardia Systems, LLC of Tucson, Arizona. Designed to operate much the same way as a human heart, this pump system replaces the two active chambers (i.e., the ventricles) of the actual human heart with corresponding artificial hardware components. As illustrated in FIG. 2, an embodiment of such air-actuated pump system 200 includes two separate chambers (sometimes interchangeably referred to as ventricles) 212 and 214 that replace, in practice, the right and left natural ventricles of the human heart, respectively. Each chamber is equipped with a respective diaphragm (schematically indicted as 216 and 218 in the right and left chamber, respectively) that has an air contact side and a blood contact side. Each diaphragm may be designed to have a shape, in an unloaded / rest position, substantially similar to that of as a spherical hemisphere. The bottom of each chamber is provided with an airline (240 and 242, in the right and left chamber, respectively). Each of the chambers is equipped with judiciously designed valves: artificial valves 244A (which may be referred as “tricuspid” valve of the pump system 200), 246A(“bicuspid” valve of the pump system 200) and 244B (“pulmonary” valve of the pump system 200), 246B (“aortic” valve of the pump system 200).

[0022] As shown in FIG. 3, in practice and prior to operation, the artificial-heartdike air-actuated pump system 200 is implanted by connecting the top of the right chamber 212 to the right atrium 112 of the human body and the top of the left chamber 214 to the left atrium 116 of the human body. The airlines 240, 242 are at least partially embedded in the patient's body and are connected to a pneumatic driver (in some currently implemented cases, the airlines 240, 242 extend outside for connection to the extemal-to-the-body pneumatic driver).

[0023] When driven by a supply of pressurized air from the pneumatic driver, each diaphragm 216, 218 discharges blood from the respective chamber 212, 214 - thereby simulating the function of a natural ventricle. This phase is referred to in the art as systole or equivalently as the ejection phase. When the pressurized air is removed from the diaphragm (during a portion of the cycle known as diastole or the filling phase), blood can enter the ventricle from the connected atrium. The rate at which blood enters the ventricle depends on the difference between the atrial pressure and the pressure on the air-side of the diaphragm. To increase this filling rate, a slight vacuum of about 10 mm Hg or so is normally applied to the air-side of the diaphragm during diastole. The artificial valves 244A, 246A, 244B, and 246Bare configured to control the flow from the respective atrium into each artificial ventricle and out to the circulatory systems, respectively. Understandably, one of the pump actuators 212, 214 uses appropriate valves to direct blood through the lungs (pulmonary system) of the human subject, while the tother pumps blood through the systemic system (the body).

[0024] The pneumatic drivers used to date still somewhat limit the degree of independent mobility of the patient. Such drivers employ compressors, vacuum pumps, and air tanks coupled to electrically actuated valves, all of which amounts to abulky apparatus that needs to be attended to and requires to be transported by and / or with the patient. Even at the approximate weight of 15 pounds and size of about 0.3 cubic feet achieved so far (the example of which is provided by the Freedom driver available from SynCardia Systems, LLC), pneumatic drivers remain an obstacle to artificial heart patients’ quality of life. It is essential that the pneumatic driver be able to provide the correct pressure balance between the left andright ventricles of the artificial heart to ensure the proper operating pressure to the pulmonary and systemic circuits regardless of the speed of operation. Typically, this requires that the driver be able to operate so as maintain, on average a mean pulmonary artery pressure of about 35 mmHg and a mean aortic pressure of about 95 mmHg. To this end, sufficient fill volume and heart rate must be achieved to supply a minimum cardiac output of 3.5 LPM.

[0025] Substantially in every application, the operation of an air-driven (more generally - fluidically-driven, as the skilled person will appreciate) pump system such as a pump with an air- driven diaphragm remains inefficient. The loss of efficiency is caused - at least in part - by operating a pump system that contain pneumatically driven activating and activated chambers (separated from one another by a flexible diaphragm) without paying attention to whether and / or when the second fluid present in the activated chamber is, under the action of the pressurized first fluid in the activating chamber, entirely forced out by the end of the pump cycle. (Such end state may be referred to as full-eject of the pump contents, or satisfaction of the full-eject condition.)SUMMARY OF THE INVENTION

[0026] Embodiments of the invention provide a pneumatically-driven pump apparatus that includes a pump system, a pneumatic driver configured to provide pneumatic power to the pump system, and electronic circuitry operably cooperated at least with a gauge apparatus of the pneumatic driver. The pump system has a rigid shell defining an internal volume that is separated by a reversibly movable chamber separator into an activating chamber and an activated chamber. The pneumatic driver includes: a compression mechanism configured to reversibly reposition an activating fluid between a first fluid location and the activating chamber, and the gauge apparatus operably cooperated with the activating fluid and configured to measure at least a time-dependent value of pressure produced by the activating fluid at the activating chamber during an operation of the pneumatic driver and to generate data representing results of such measurement. The electronic circuitry is configured to determine in real time, based at least in part on the data received from the gauge apparatus, whether a full-eject condition was satisfied during an operation of the pump system and to produce an output representing a result of such determination. In at least oneimplementation of the apparatus, at least one of the following conditions is satisfied: the chamber separator is configured as a flexible diaphragm that is substantially fluidly impenetrable; a portion of the compression mechanism containing the activating fluid is fluidly connected only with the activating chamber; and the electronic circuitry is configured to determine, as a function of time and based on the data, a value of a time derivative of the at least time-dependent value of pressure produced by the activating fluid at the activating chamber. Optionally, and substantially in every implementation of the apparatus, the compression mechanism may include a spatially- repositionable component. Optionally, and substantially in every implementation of the apparatus, the compression mechanism may incorporate (i) at least one piston slidably mounted inside a piston housing and / or (ii) a source of compressed fluid. Alternatively or in addition, in at least one of the embodiment the activated chamber includes an inlet and an outlet that may be spatially separated from one another. Alternatively or in addition, and substantially in every implementation of the apparatus, the electronic circuitry may include analog electronic circuitry and / or a processor configured to determine, based on the data, whether the pump system satisfies the full-eject condition by determining a time-dependent value of a time-derivative of a function of the at least the time-dependent value of the pressure. (In specific cases, such function may be a product of a volume of the activating fluid in the compression mechanism that is repositioned between the first fluid location and the activating chamber and the pressure - or a natural logarithm of such product.) Optionally, the pump system may be configured as a ventricle portion of an implantable artificial heart apparatus.

[0027] Embodiments of the invention additionally provide use of any embodiment of the apparatus alluded to above for repositioning the chamber separator configured as a flexible substantially fluidly-impenetrable diaphragm within the rigid shell to change at least one of a volume of the activating chamber and a volume of the activated chamber, and / or use of such apparatus for exchanging blood between an implantable artificial heart apparatus and a pulmonary artery and / or an aorta.

[0028] Embodiments further provide a computer-implemented method that includes performing the following steps with the use of the computer: recording at least a value of pressure produced by the activating fluid in the activating chamber of the pump system (of substantiallyevery implementation of the apparatus alluded to above) during repositioning of the activating fluid between the compression mechanism and the activating chamber of the pump system and measured with the gauge apparatus; determining based on the at least the value of pressure whether a full-eject of contents of the activated chamber of the pump system has occurred during a pump cycle; and if the full-eject has occurred, generating first indicia representing such occurrence (otherwise generating second indicia representing lack of such occurrence).

[0029] Embodiment additionally provide a method directed to configuring an embodiment of the apparatus alluded to above at least in part by performing the following steps: an initial step of increasing a pressure of an activating fluid at an activating chamber of a pump system with the use of a first pneumatic drive while measuring the pressure with a gauge apparatus that is operably cooperated with the activating fluid to determine whether an operation of the pump system satisfies a full-eject condition, and a conditional step determined on whether the operation of the pump system driven by the first pneumatic drive satisfies the full-eject condition. Specifically, if the operation of the pump system driven by the first pneumatic drive does not satisfy the full-eject condition, the conditional step include replacing the first pneumatic drive with a second pneumatic drive configured to deliver the activating fluid at an auxiliary pressure that is higher that the maximum pressure provided by the first pneumatic drive, and then repeating the initial step. However, if the operation of the pump system driven by the first pneumatic drive does satisfy the full-eject condition, the conditional step includes identifying a value of said pressure at which the full-eject has been satisfied as an operating pressure for the first pneumatic drive to drive the pump system. At least one embodiment of the method includes determining whether the operation of the pump system satisfies the full-eject condition based at least in part on recording with electronic circuitry, operably connected at least with the gauge apparatus, a value of a time derivative of a the pressure as a function of time (optionally, such determining may include recording a value of a time-derivative of a volume of the activating fluid repositioned from the compression mechanism to the activating chamber. The process of determination of whether the operation of the pump system satisfies the full-eject condition can optionally be performed with the use of a logarithmic function of a product of the measured pressure and a geometric parameter representing the compression mechanism of the apparatus.

[0030] Embodiments of the invention also provide a computer program product for governing an operation of a pneumatically driven pump system, the computer program product comprising a computer usable tangible non-transitory medium having computer readable program code thereon. The computer readable program includes program code for measuring at least a value of pressure of the activating fluid in substantially every embodiment of the apparatus alluded to above during repositioning of the activating fluid between the first fluid location and the activating chamber of the pump system. The computer readable program further includes program code for ascertaining whether contents of the activated chamber of the pump system have been fully ejected therefrom during a systolic part of a cycle of operation of the pump system based on the at least the value of pressure and generating first indicia of an occurrence of a full-eject and identifying at least such value of pressure as an operating pressure to be delivered to the activating chamber by the pneumatic driver of the system if it is discovered that the full-eject has occurred and second indicia representing a need to replace the pneumatic driver if it is discovered that the full-eject has not occurred.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will be more fully understood by referring to the following Detailed Description of Specific Embodiments in conjunction with the Drawings, of which:

[0032] FIG. l is a schematic representation of a human heart.

[0033] FIG. 2 is a schematic view of an embodiment of the SynCardia LLC artificial heart apparatus.

[0034] FIG. 3 is a representation of the artificial heart of FIG. 2 connected to the heart atria of a human body.

[0035] FIG. 4 is a schematic representation of a portion of an embodiment of the invention /

[0036] FIGs. 5A, 5B illustrate, respectively, situations when the main chamber of the pump-system of the embodiment of FIG. 4 in a full-fill status and in a full-eject status.

[0037] FIG. 6A: Schematic of structure and operation of a volume-changer type drive with the pneumatic pump-system of FIG. 4. FIG. 6B: schematic representation of the overallapparatus of the pneumatically-driven pump system employing the volume-changer type pneumatic drive of FIG. 6A.

[0038] FIG. 7A: Schematic illustrating operation of the compressed air-source type drive with the pneumatic pump-system of FIG. 4 during the phase of filling the activating chamber of the pump-system with gas. The valve in line 426 that fluidly connects the source 730 with the activating chamber is not shown for simplicity of illustration.

[0039] FIG. 7B : Schematic illustrating operation of the compressed air-source drive with the pneumatic pump-system of FIG. 4 during the phase of filling the activated chamber of the pump-system with external fluid.

[0040] FIGs. 8A, 8B are plots (waveforms) representing, as functions of time, pressure (FIG. 8A) of the activating fluid (air, in one implementation) at and outflow of the activating fluid from (FIG. 8B) the activating chamber of the pump of FIG. 4 during the pump cycle.

[0041] FIG. 9 presents results of measurements of pump cycles of two different embodiments of the pump, performed according to an embodiment of the detection scheme configured according to the idea of the invention.

[0042] FIGs. 10A, 10B illustration of experimental data acquired during the process of determination of whether a given embodiment of the pneumatically-driven pump apparatus satisfies the full-eject condition performed with the use of an embodiment of the invention.DETAILED DESCRIPTION

[0043] FIG. 4 schematically illustrates a portion of the fluid-driven (in one case - air driven) pump system 400 of interest. Here, fluid 1 (such as air or gas, in one example, reversibly filling the activating chamber 410 that is separated from the activated chamber 414 by the reversibly moveable chamber separator 418; shown in this example as a flexible diaphragm) is pumped in and out of the chamber 410 by the pneumatic drive 420 (not shown), thereby reversibly pushing the flexible chamber separator 418 towards the wall of the chamber 414 and causing, in alternation, at least partial emptying of the local volume of the chamber 414 through the outlet and at least partial filling of this local volume through the inlet. As fluid 1 is removed from the activating chamber 414, fluid 2 can enter the activated chamber 414 and vice versa. The pump 400 may be operatedwith, for example, a piston / cylinder driver connected to the pump system to alternatively reduce and then expand the volume of the activating chamber, or be of a valve-operated type known in the art.

[0044] For proper operation, inlet / outlet of the activated chamber 412 are equipped with respective appropriately structured valves, as a person of ordinary skill in the art would readily understand.) The chamber separator is judiciously configured such that, depending on its position / orientation within the overall volume defined by the shell 422, either of the corresponding local volumes of the chambers 410, 414 can be reduced to substantially zero or increased to substantially coincide with the overall volume. For example, in the case when the inner surface of the shell 422 defines a substantially spherical surface, the chamber separator 418 may be designed to have a shape, in an unloaded / rest position, substantially similar to that of as a spherical hemisphere (in one case, to be configured as a flexible diaphragm). The shell is configured to substantially not allow the overall volume within the shell to be varied, for example the shell may be made from a mechanically rigid material such as isoplast or stainless steel. Understandably, the chamber separator 418 can be, generally, a piston, a membrane or diaphragm, or other moveable or distensible means to keep the fluid in the activated chamber and the air in the activating chamber separated while the latter forces the former from the outlet of the activated chamber. Appreciably, substantially any complementary shapes of the shell 422 and the chamber separator 418 can serve provided the means for keeping the first and second fluids separate will, under the action of the pressurized first fluid, fully distend or move into a position such that there is no longer any room in the shell profile for the second fluid that needs to be pumped.

[0045] In describing various embodiments of the apparatus of the invention and / or methodology of the invention, the pump system may be interchangeably referred to as air-operated (or driven), gas operated (or driven), or, more generally, fluid-operated (or driven) or by a similar term. Each of such references or descriptions implies that the chamber separator 418 is moved or repositioned in response to pressure of fluid / air / gas formed by the pneumatic drive 420 on the activating-chamber side of the pump system.

[0046] When using an air-actuated pump such as that referred to above, it is frequently necessary to ascertain if (or whether) the fluid in the activated chamber at the beginning of the pump cycle has been entirely forced out of the pump by the end of the pump cycle due to operation of thechamber separator driven by the pressurized fluid (for example, air) delivered into the activating chamber - that is, whether the full-eject condition has been satisfied. In pump systems where there is no in situ mechanism to measure the fluid contents of the pump and, therefore, it is of value in these pump systems to identify if full-eject has taken place. Accordingly, in accordance with embodiments of the present invention, methods and apparatus are disclosed for identification / determining of whether the activated chamber of a multiple-chamber fluid pump system, driven by an activating chamber connected to a pneumatic drive, has all fluid content of the activated chamber fully ejected from it.

[0047] Explanations of some aspect(s) of embodiments of the invention may be presented below in reference to a very specific and non-limiting example when the discussed pump system is used in an artificial heart apparatus. However, as a skilled artisan readily understands, such reference is used only as an example while plethora of other, non-medical applications of the discussed pump system exist, most of which involve non— animate situations. See, for example, blog.craneengineering.net / how-do-air-operated-double-diaphragm-pumps-work.In such specific non-limiting example, when the pump system 400 is used as a ventricle of the artificial heart such as ventricle 212 of FIG. 2, for example, the activating chamber 410 may be an air chamber - that is, the first fluid is air, the activated chamber 414 is a blood chamber - that is, the second fluid is blood, and the pipe or passage 426 represents the external pneumatic access to the chamber 414, similarly to the airline of the embodiment of FIG. 2, the inlet is a blood chamber inlet, and the outlet is a blood chamber outlet, while the flexible membrane 418 separated blood from air / gas.

[0048] By analogy with terminology used describe a cardiac cycle, a portion of the overall pumping cycle (the cycle of operation of the pump system 400) during which contents of the activated chamber 412 are being driven out (ejected) from the activated chamber by repositioning of the chamber separator 418 (caused by increasing pressure inside the activating chamber 410) may be referred to in this disclosure as a systolic portion of the pump cycle. Similarly, the remaining portion of the overall pumping cycle during which the activated chamber 412 is being filled with contents through its inlet driven by a reversed repositioning of the chamber separator 418 (which isnow moving to reduce the volume of the activating chamber) may be referred to as a diastolic portion of the pump cycle.

[0049] With reference to the schematics of FIGs. 5 A, 5B, when fluid 1 in the chamber 410 substantially completely fills the overall volume of the volume-limiting shell or housing 422 during the diastolic portion of the pump cycle (this corresponds to the situation when the local volume of the activated chamber 414 is reduced substantially to nothing), the condition known as full-fill is satisfied. Alternatively, when fluid 1 in the activating chamber 410 substantially completely fills the overall volume of the shell 422 during the systolic portion of the pump cycle (which corresponds to the situation when the local volume of the activating chamber is reduced to practically nothing), the condition known as full-eject is satisfied.

[0050] Why is the question of whether full-eject occurs is even of importance? - The need to be able to confirm that the full-eject condition has been, indeed satisfied is driven by persisting shortcomings and problems caused in operation of a typical air-driven pump when this is not known.

[0051] In particular - as is well appreciated in related art - one approach presently used to ensure that the full-eject takes place is to set the maximum pressure of fluid 1 (that is reached during the portion of the pneumatic drive operation cycle delivering fluid 1 to the activating chamber 410) to a value that is greater than operationally required. In other words - to inject enough air into the activating chamber 410 at a high enough pressure that it is physically impossible for any liquid to avoid being ejected from the activated chamber 412 of the pump. At the end of the expulsion phase, the pressure in the pump will be equal to the maximum pressure designed into the actuator system. Therefore, the process of determining that full-eject takes place is simplified to simply assuring that that maximum pressure is achieved at the end of the expulsion phase of the pump cycle.

[0052] (Only for the sake of entertaining a specific example of an artificial heart system, this corresponds to setting the maximum pressure of air / gas delivered through the connecting pipe 426 with the use of pneumatic drive during systole to a value greater than what is seen as clinically necessary for full-eject. In such specific example, the currently conventionally used approach is to ensure that the maximum pressure is simply set to a value above that ever expected to be encountered: automated monitoring of full-eject is not typically implemented in artificial heartdriver design; rather, conventional systems of related art simply allow an operator setting of the maximum driver pressure or the drive pressure to be set to a high enough value to properly perform in worst-case situations.)

[0053] This status quo “overshooting” operation of the pump system causes multiple shortcomings and / or problems. For example, in a pneumatically activated device, the more pressurized gas (fluid 1) is added to the activated chamber 410 of the embodiment, the greater is energy required to fully eject fluid 2 from the chamber 414. Therefore, knowledge of the very fact of occurrence (and / or the moment of occurrence) of the full -eject allows the user to end the current “fluid 2 pump-out” phase of the operation of the system 200 and to begin a new “fluid 2 pump-in” phase resulting in minimization of energy required to activate the system 200.

[0054] Furthermore (and in the case of use of the pump 400 in the artificial heart system, for example), since the health of blood (and, therefore, the ability of blood to perform its functions such as transporting oxygen and nutrients, forming blood clots to prevent excess blood loss etc.) may be and practically often is sensitive to the presence of and contact with artificial materials, the damage to blood passing through the chamber 414 may manifest and be more pronounced the longer the blood is in contact with artificial surfaces of the chamber 414. Here, it would be beneficial to minimize dwell time of blood in a ventricle of the artificial heart composed of synthetic materials. Therefore, knowledge that all blood has left the ventricle prior to the end of a cycle is pertinent to ensuring the minimum dwell time.

[0055] In addition, in the same specific case, the longer is the time during which air / gas is being injected into an artificial ventricle the lower is the rate at which such ventricle can be operated. Therefore, the addition of air / gas to the air / gas side of the ventricle after full-eject has taken place results in a reduced heart rate and, thereby, a reduced maximum cardiac output.

[0056] For any these reasons, the very knowledge of if (and, preferably, when) full-eject has occurred results in a safer, more efficient, and more capable driver mechanism of the discussed pump system.

[0057] According to the idea of the present invention, a persisting in related art problem of lack of knowledge of whether the pump system (that includes a pneumatically activating chamber and an activated chamber separated from one another by a chamber separator such as, for example, aflexible diaphragm) reaches the full -eject condition is solved by observing the change of a derivative of a pressure in the activated chamber of the pump system as a function of time to determine whether during the operation of a given pump the full-eject occurs (thereby immediately differentiating those pumps that operate as desired from those possibly considered to be deficient) and, based on results of such determination, making a decision of whether such given pump is required to be operated with a different pneumatic driver in order to reach the full-eject during operation.

[0058] Examples of Types of Drivers. Although the general approach discussed above is applicable to substantially all drivers that may be used with the pump system 400, there are two general classes of pneumatic drivers currently commonly in use. The first class employs a compressing mechanism utilizing a piston / cylinder arrangement that is connected directly to the activating chamber of the pump-system and that maintains a substantially fixed number of molecules of fluid 1 in the combined driver / activating chamber volume throughout a phase of the cycle during which fluid 1 is delivered / pumped into the activating chamber. This class of compressing mechanism (pneumatic driver) 420, often referred to as a volume-change device, is schematically depicted in FIG. 6 as 620. Another class of drivers utilizes a source of compressed fluid 1 (air / gas) 730 (such as a high-flow compressor, compressed air tank, etc.) and appropriate pneumatic valves (not shown, in line 426) to introduce such compressed fluid (air / gas) into the activating chamber side of the pump system 400, and another pneumatic valve 740 to allow air / gas to be expelled from the activating chamber 410 of the shell 422. In some instances of using a driver of this class, a vacuum pump can be additionally used to aid the rate at which fluid 1 (air / gas) can exit the shell 422. The operation of this class of pneumatic drive 420 is schematically illustrated in FIGs. 7A, 7B as operation of the drive 720.)Example 1.

[0059] With that said, one implementation of the invention is rooted in the empirical observation and / or detection of a typical time-dependencies of waveforms characterizing air pressure (i.e., the fluid 1 pressure) at the activating chamber 410) during the pumping process. Shown in FIGs. 8A, 8B, respectively, these waveforms result from the pumping action itself. In reference to the arrangement of FIG. 4, for example, the waveform of FIG. 8 A represents the typicalpressure of fluid 1 delivered into the activating chamber 410 when fluid 2 is being ejected out of the outlet of the activated chamber 412 (the systolic portion of the pump cycle), while the waveform of FIG. 8B represents the flow of the fluid 1 flow out of the activating chamber 410 when fluid 2 enters the activated chamber through the inlet of the activated chamber or, alternatively, the flow of fluid 2 itself into the activated chamber (a diastolic portion of the pump cycle).

[0060] Notably, the transition of the waveform from the waveform 800A of FIG. 8 A to 800B of FIG. 8B follows an informative pattern. The leftmost portion 804 of the curve 800A corresponds to the time window when the air (~ fluid 1) is just beginning to enter the activating chamber 410, so the pressure inside the activating chamber begins to rise At the beginning, pressure produced by fluid 1 increases at the beginning of the operation of the compression mechanism (initial reduction of the piston / cylinder volume, in case of utilizing pneumatic driver 620), leading to the fluid 2 being pumped out of the activated chamber at about 808. A portion 812 of the curve (between 804 and 808) corresponds to the continued operation of the compression mechanism, when fluid 2 ejected from the activated chamber increases the available volume of the activating chamber to substantially match the reduction in the piston / cylinder volume (in case of utilizing pneumatic driver 620). This flattening of the waveform 800A in the range 812 indicates that the amount of pressurized air (fluid 1) entering the activating chamber 410 is substantially matched by the amount of fluid 2 being pumped out of the activated chamber through the outlet into the environment fluidly connected with the pump: no net volume change occurs, thus this fluid volume-matching keeps the pressure during this portion of the pump cycle and in this region 812 of the curve 800A relatively constant. At the end of this flattened portion 812 of the curve 800 A, at 816, substantially no more fluid 2 remains in the activated chamber and the additional air (fluid 1) being forced into the activating chamber 410 of the pump causes the pressure to abruptly rise. The abrupt peaking 824 of pressure in the activating chamber occurs because the contents of the activated chamber have been fully expelled. That is, the peaking behavior at the end of the fluid 2 expulsion phase of the pump cycle indicates that full-eject has occurred. This feature of the waveform 800A may be referred to as a “full-eject feature” of the pressure in the activating chamber and its detection during the pumping cycle) serves as indicia that full-eject has taken place.

[0061] The flatened peak of the curve represents a period of decompression, while part 830 of the waveform 800B represents the portion of the pump cycle when fluid 2, being driven through the inlet into the activated chamber 412 of the shell by the reverse repositioning of the chamber separator 418, substantially fills the activated chamber 412 and when fluid 1 is leaving the activating chamber 410 due to displacement caused by the in-flow of the fluid 2 into the activated chamber of the shell.

[0062] Accordingly, in one implementation of the idea of the invention, the observation or detection of the change in time-derivative of pressure at the activating chamber 410 serves to identify the beginning portion of the full-eject feature when pressure abruptly rises immediately after full-eject occurs. The results of measurements of pump cycles of two different embodiments of the pump, performed according to this detection scheme, are illustrated in FIG. 9: curves Pl, P2, and the respectively corresponding dPl / dt, dP2 / dt clearly evidence the occurrence of the full eject in the first pump cycle and the lack of full-eject during the second pump cycle. The skilled artisan will immediately appreciate that the use of a time derivative of pressure is more sensitive and less prone to error than the use of pressure itself in determining if full-eject has occurred.Example 2.

[0063] In a related case (and considering for simplicity of presentation the case of the piston / cylinder compression mechanism, FIG. 6), the volume of the cylinder is coupled directly to the volume of the activating chamber 410 of the air-activated pump 400. During the relevant portion of the ejection stroke, the number of air molecules in this combined region does not change. Further, for a pump that operates isothermally (where the temperature of the air used to actuate the pump does not change) one can employ the ideal gas law to implement another embodiment of the invention.

[0064] As is well-known in the art, gasses generally conform to the ideal gas law,

[0065] PV = nRT, (1)

[0066] where P represents the pressure of gas delivered to the activating chamber from the compression mechanism, V represents gas volume, n is the number of gas molecules, A is a known constant, and / is the gas temperature. Expressing the gas volume as the combination of the volumeVac of gas in the activating chamber 410 of the pump-system 400 and the volume Vcyiof gas contained in the actuator (piston) cylinder and the passage connecting the actuator cylinder with the activating chamber at the very beginning of the systolic portion of the pump cycle, see FIG. 6 (that is, at the moment of time substantially corresponding to the outermost left point of the waveform 800A of FIG. 8A), , one obtains

[0067] PVcyl = nRT-PVac(2)

[0068] The assumption here is that the user knows the volume of the actuator cylinder (and, in general, the relevant volume of the compression mechanism) but does not know the volume of the activating chamber (since the very problem being solved is to determine / identify the occurrence of the full-eject). Taking the time derivative of Eq. (2) results in

[0070] Since nRT is assumed constant, then when the volume of the activating chamber becomes substantially static (~ does not change any more) due to all fluid 2 having been expelled from the activated chamber 412 (see FIG. 5B), the left-hand side of Eq. (3) equals to zero. That is, when full- eject occurs at the end of the systolic portion of the pump cycle,

[0072] Using the same experimental data utilized in FIG. 10 of Example 1, one arrives at the results presented in FIGs. 10A and 10B.

[0073] Notably,

[0074] Accordingly, alternatively or in addition, the change in time of the natural log of the PE product measured at the compression mechanism on the side of the activating chamber to ascertain an occurrence of full-eject (or lack thereof), if there are practical advantages in doing so. (The skilled person will readily appreciate that the practical advantage of utilizing the natural logarithms based calculation presents itself when the electronic circuitry used to process these measurement data is of the type of analog electronic circuitry.)

[0075] The overall apparatus includes an embodiment of the pump system as discussed above, a pneumatic driver configured to provide pneumatic power to the pump system and containing a compression mechanism configured to reposition an activating fluid between a first fluid location and the activating chamber of the pump system, a gauge apparatus operably cooperated with the activating fluid, and electronic circuitry. Specifics of the implementation of the hardware of the embodiment of the invention differ depending, in part, on the type of the pneumatic driver. When operation of the compression mechanism turns on the use of piston / cylinder (FIGs. 6A, 6B), the first fluid location is that between the piston and the activating chamber. When operation of the compression mechanism of the pneumatic drive turns on the use of the source of compressed gas (FIGs. 7A, 7B), the first location is that between the in-line valve (providing access to the compressed gas from the source 230 to the chamber 41). The gauge apparatus is configured to measure at least a time-dependent value of pressure (produced by the activating fluid in the activating chamber during an operation of the pneumatic driver) and the volume of activating fluid delivered to the activating chamber, and may be appropriately structured as one of the many devices used for this purpose in the art.

[0076] The real-time determination of whether the operation of the pump system satisfies a full-eject condition can be carried out - at least in one case - by electronic circuitry operably cooperated with the gauge apparatus based on the measurement data received from the gauge apparatus. The same electronic circuitry mat be configured to produce an output signifying a result of such determination. (Optionally, such electronic circuitry includes analog circuitry and / or a digital circuitry such as a programmable processor.) Optionally, based on the determination whether the full-eject condition is achieved, the electronic circuitry may not only govern the operation of the overall apparatus (for example, to identify the pressure level at which the activating fluid should be delivered to the activating chamber from the pneumatic drive to ensure that the fulleject is observed in each of the pumping cycles) but also provide indicia of whether it is appropriate to replace a given pneumatic drive with another one (which may be the case when operational characteristics of the first pneumatic drive simply do not allow the apparatus to reach the full-eject during the pumping cycle, for example due to inability of the first pneumatic drive to create the pressure in the activating chamber that would lead to the full-eject).

[0077] For the purposes of this disclosure and accompanying claims, a real-time performance of a system is understood as performance that is subject to operational deadlines from a given event to a system’s response to that event. For example, a real-time extraction of data (such as that representing a reading of the flow meter or a pressure sensor) from a buffer of a corresponding device or from tangible non-transient storage medium may be one triggered by the user or an appropriate electronic circuitry and executed substantially simultaneously with and without interruption of a measurement during which such data have been recorded.

[0078] As the skilled artisan will readily appreciate, one practically applicable way of improving the operation of the pump system once it is discovered that the full-ejection condition does not occur (as in the example of operation of pump #2 in FIG. 9 or pump #2 in FIG. 10B) would be implemented by slowly varying the duration of the systolic period of the pump cycle until the full-eject signal is detected. For example, the duration of the systolic portion of the pump cycle can be first slowly increased, then reduced and then increased again to regain the full-eject signal.

[0079] For the purposes of this disclosure and the appended claims, the expression of the type “element A and / or element B” is defined to have the meaning that is equivalent to “at least one of element A and element B”.

[0080] The use of the terms "substantially", "approximately", "about" and similar terms in reference to a descriptor of a value, element, property or characteristic at hand is intended to emphasize that the value, element, property, or characteristic referred to, while not necessarily being exactly as stated, would nevertheless be considered, for practical purposes, as stated by a person of skill in the art. These terms, as applied to a specified characteristic or quality descriptor means "mostly", "mainly", "considerably", "by and large", "essentially", "to great or significant extent", "largely but not necessarily wholly the same" such as to reasonably denote language of approximation and describe the specified characteristic or descriptor so that its scope would be understood by a person of ordinary skill in the art. In one specific case, the terms "approximately", "substantially", and "about", when used in reference to a numerical value, represent a range of plus or minus 20% with respect to the specified value, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2% with respect to the specified value. As a non-limiting example, two values being "substantially equal" to one another implies that thedifference between the two values may be within the range of + / - 20% of the value itself, preferably within the + / - 10% range of the value itself, more preferably within the range of + / - 5% of the value itself, and even more preferably within the range of + / - 2% or less of the value itself.

[0081] References throughout this specification to "one embodiment," "an embodiment," "a related embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with the referred to "embodiment" is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment, “ "in an embodiment, “ and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. It is to be understood that no portion of disclosure, taken on its own and in possible connection with a figure, is intended to provide a complete description of all features of the invention.

[0082] Within this specification, embodiments have been described in a way that enables a clear and concise specification to bet written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the scope of the invention. In particular, it will be appreciated that all features described herein at applicable to all aspects of the invention.

[0083] It is understood that, regardless of whether a particular reference to the use of a processor has been made in this disclosure, the implementation of the method of the invention may and preferably does include a processor controlled by instructions stored in a memory. The memory may be random access memory (RAM), read-only memory (ROM), flash memory or any other memory, or combination thereof, suitable for storing control software or other instructions and data. Those skilled in the art should also readily appreciate that instructions or programs defining the functions of the present invention may be delivered to a processor in many forms, including, but not limited to, information permanently stored on non-writable storage media (e.g. read-only memory devices within a computer, such as ROM, or devices readable by a computer I / O attachment, such as CD-ROM or DVD disks), information alterably stored on writable storage media (e.g. floppy disks, removable flash memory and hard drives) or information conveyed to a computer through communication media, including wired or wireless computer networks. In addition, while the invention may be embodied in software, the functions necessary to implement the invention mayoptionally or alternatively be embodied in part or in whole using firmware and / or hardware components, such as combinatorial logic, Application Specific Integrated Circuits (ASICs), Field- Programmable Gate Arrays (FPGAs) or other hardware or some combination of hardware, software and / or firmware components.

[0084] While the invention is described through the above-described exemplary embodiments, it will be understood by those of ordinary skill in the art that modifications to, and variations of, the illustrated embodiments may be made without departing from the inventive concepts disclosed herein. Accordingly, the implementation of the invention should not be viewed as being limited to the disclosed embodiment(s).

Claims

CLAIMS1. An apparatus comprising: a pump system having a rigid shell defining an internal volume that is separated by a reversibly movable chamber separator into an activating chamber and an activated chamber; a pneumatic driver configured to provide pneumatic power to the pump system, wherein the pneumatic driver includes: a compression mechanism configured to reversibly reposition an activating fluid between a first fluid location and the activating chamber; and a gauge apparatus operably cooperated with said activating fluid and configured to measure at least a time-dependent value of pressure produced by the activating fluid at the activating chamber during an operation of the pneumatic driver and to generate data representing results of such measurement; and electronic circuitry operably cooperated with said gauge apparatus and configured to determine in real time, based at least in part on the data received from the gauge apparatus, whether a full-eject condition was satisfied during an operation of the pump system and to produce an output representing a result of such determination.

2. An apparatus according to claim 1, wherein at least one of the following conditions is satisfied: the chamber separator is configured as a flexible diaphragm that is substantially fluidly impenetrable; and a portion of the compression mechanism containing said activating fluid is fluidly connected only with the activating chamber; andthe electronic circuitry is configured to determine, as a function of time and based on said data, a value of a time derivative of the at least time-dependent value of pressure produced by the activating fluid at the activating chamber.

3. An apparatus according to one of claims 1 and 2, wherein the compression mechanism includes a spatially-repositionable component.

4. An apparatus according to one of claims 1 and 2, wherein the compression mechanism incorporates (i) at least one piston slidably mounted inside a piston housing and / or (ii) a source of compressed fluid.

5. An apparatus according to one of claims 1 to 4, the activated chamber includes an inlet and an outlet.

6. An apparatus according to claim 5, wherein the inlet and the outlet are spatially separated from one another.

7. An apparatus according to one of claims 1 to 6, wherein said electronic circuitry includes analog electronic circuitry and / or a processor configured to determine, based on said data, whether the pump system satisfies the full-eject condition by determining a time-dependent value of a time-derivative of a function of the at least the time-dependent value of said pressure.

8. An apparatus according to claim 7, wherein said function is a product of a volume of the activating fluid in the compression mechanism that is repositioned between the first fluid location and the activating chamber and said pressure or a natural logarithm of such product.

9. An apparatus according to one of claims 1 to 8, wherein the pump system is configured as a ventricle portion of an implantable artificial heart apparatus.

10. Use of the apparatus according to one of claims 1 to 9 for repositioning the chamber separator configured as a flexible substantially fluidly-impenetrable diaphragm within the rigid shell to change at least one of a volume of the activating chamber and a volume of the activated chamber.

11. Use of the apparatus according to claim 9 for exchanging blood between an implantable artificial heart apparatus and a pulmonary artery and / or an aorta.

12. A computer-implemented method comprising: with the use of a computer: recording at least a value of pressure produced by the activating fluid in the activating chamber of the pump system the apparatus according to one of claims 1 to 9 during repositioning of the activating fluid between the compression mechanism and the activating chamber of the pump system and measured with the gauge apparatus; with the use of the computer, determining based on the at least said value of pressure whether a full-eject of contents of the activated chamber of the pump system has occurred during a pump cycle; and if the full-eject has occurred, generating, with the use of the computer, first indicia representing such occurrence, otherwise generating second indicia representing lack of such occurrence.

13. A method compri sing : configuring the apparatus according to one of claims 1 to 9 at least in part by performing the following steps:(13 A): increasing a pressure of an activating fluid at an activating chamber of a pump system with the use of a first pneumatic drive while measuring said pressure with a gauge apparatus that is operably cooperated with the activating fluid to determine whether an operation of the pump system satisfies a full-eject condition, and(13B) i) if the operation of the pump system driven by the first pneumatic drive does not satisfy the full-eject condition, replacing the first pneumatic drive with a second pneumatic drive configured to deliver the activating fluid at an auxiliary pressure that is higher that the maximum pressure provided by the first pneumatic drive, and repeating step (14A); or ii) if the operation of the pump system driven by the first pneumatic drive does satisfy the full-eject condition, identifying a value of said pressure at which the full-eject has been satisfied as an operating pressure for the first pneumatic drive to drive said pump system.

14. A method according to claim 13, comprising determining whether the operation of the pump system satisfies the full-eject condition based at least in part on recording with electronic circuitry, operably connected at least with the gauge apparatus, a value of a time derivative of a said pressure as a function of time.

15. A method according to claim 14, wherein said determining includes recording a value of a time-derivative of a volume of the activating fluid repositioned from the compression mechanism to the activating chamber.

16. A method according to claim 13, comprising determining whether the operation of the pump system satisfies the full-eject condition with the use of a logarithmic function of a product of said pressure and a geometric parameter representing the compression mechanism of the apparatus.

17. A computer program product for governing an operation of a pneumatically driven pump system, the computer program product comprising a computer usable tangible non-transitory medium having computer readable program code thereon, the computer readable program including: program code for measuring at least a value of pressure of the activating fluid in the apparatus according to one of claims 1 to 9 during repositioning of said activating fluid between the first fluid location and the activating chamber of the pump system; program code for ascertaining whether contents of the activated chamber of the pump system have been fully ejected therefrom during a systolic part of a cycle of operation of the pump system based on the at least said value of pressure and generating first indicia of an occurrence of a full-eject and identifying the at least said value of pressure as an operating pressure to be delivered to the activating chamber by the pneumatic driver of the system if it is discovered that the full-eject has occurred and second indicia representing a need to replace the pneumatic driver if it is discovered that the full-eject has not occurred.

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