Apparatus for tissue transport and preservation

Abstract

Systems and methods of the invention generally relate to prolonging viability of bodily tissue, especially lung tissue, through the use of an expandable accumulator to maintain a constant pressure within the lumen of the organ even during external pressure fluctuations due to, for example, flight. Systems and methods may include prolonging donor organ viability in storage through the use of an organ container that mimics the geometry and orientation of the organ in vivo.

Claims

1. A method for storage of an organ, the method comprising: providing an organ container comprising: an expandable accumulator comprising an expandable inner volume; and an organ adapter comprising a lumen in fluid communication with the expandable inner volume and configured to be coupled to a lumen of an organ to form a closed air system between the expandable inner volume and the lumen of the organ, wherein the expandable accumulator has an expansion resistance that is less than the expansion resistance of the lumen of the organ, such that the expandable inner volume is operable to expand and contract in response to changes in ambient pressure to maintain a desired pressure differential between the lumen of the organ and a variable ambient pressure and coupling the lumen of an organ to the organ adapter.

2. The method of claim 1, wherein the organ is one or more lungs and the lumen of the organ is selected from the group consisting of a trachea or bronchus of the one or more lungs.

3. The method of claim 1, wherein the organ container further comprises an inlet comprising a lumen and coupled to the expandable accumulator by an inlet valve such that the lumen of the inlet is in fluid communication with the lumen of the organ when the inlet valve is opened and the closed air system between the expandable inner volume and the lumen of the organ is formed when the inlet valve is closed, the method further comprising; coupling a gas source to the inlet; opening the inlet valve; filling the lumen of the organ with gas from the gas source to a desired pressure; closing the inlet valve; removing the gas source from the inlet; and closing the organ container with the organ disposed therein.

4. The method of claim 1, wherein the expansion resistance of the expandable accumulator is adjustable.

5. The method of claim 2, wherein the organ container further comprises a raised central portion configured to be placed against an organ within the organ container, the method further comprising disposing the one or more lungs against the raised central portion.

6. The method of claim 1, wherein the expandable accumulator comprises a bellows.

7. The method of claim 1, wherein the expandable accumulator comprises a weight that provides the expansion resistance of the expandable accumulator.

8. The method of claim 1, wherein the expandable accumulator comprises a spring that provides the expansion resistance of the expandable accumulator.

9. The method of claim 1, wherein the expandable accumulator comprises an expandable bladder comprising an elastic material wherein the elastic material provides the expansion resistance of the expandable accumulator.

10. The method of claim 1, wherein the expandable accumulator comprises a rolling diaphragm.

11. The method of claim 1, wherein the expandable accumulator has an adjustable volume, the method further comprising adjusting the volume of the expandable accumulator based on ambient pressure when coupling the lumen of the organ to the organ adapter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a system including a contained bellows-type expandable accumulator.

(2) FIG. 2 shows a system including an exposed bellows-type expandable accumulator.

(3) FIG. 3 shows a system including a rolling diaphragm expandable accumulator with a spring in compression providing expansion resistance.

(4) FIG. 4 shows a system including a rolling diaphragm expandable accumulator with a spring in tension providing expansion resistance.

(5) FIG. 5 shows a system including a balloon-type expandable accumulator.

(6) FIG. 6 shows a system including a contained bellows-type expandable accumulator with a weight providing expansion resistance.

(7) FIG. 7 shows a perfusion-type organ storage container with an expandable accumulator providing pressure control for a lumen of a stored organ.

(8) FIGS. 8A and 8B show an organ container with a raised central portion.

(9) FIG. 9 shows a pair of lungs disposed on the raised central portion of an organ container

(10) FIGS. 10A and 10B show an organ adapter.

(11) FIG. 11 shows an external view of a closed organ container with an accumulator according to certain embodiments.

(12) FIG. 12 shows an exploded view of an organ container with an accumulator according to certain embodiments.

(13) FIG. 13 shows a cross-sectional view of a closed organ container with an accumulator according to certain embodiments.

(14) FIG. 14 shows an external view of an open organ container with an accumulator according to certain embodiments.

(15) FIG. 15 shows an external view of an open organ container with an accumulator and a support tray according to certain embodiments.

(16) FIG. 16A shows a transverse cross-sectional view of an approximately empty accumulator according to certain embodiments.

(17) FIG. 16B shows a lateral cross-sectional view of an approximately empty accumulator according to certain embodiments.

(18) FIG. 17 shows a lateral cross-sectional view of an approximately half full accumulator according to certain embodiments.

(19) FIG. 18 shows a lateral cross-sectional view of an approximately full accumulator according to certain embodiments.

(20) FIG. 19 shows an exploded view of an accumulator according to certain embodiments.

(21) FIG. 20 shows a pressure vs. volume curve for an ex-vivo lung model.

(22) FIG. 21 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator based on various atmospheric pressures at recovery.

(23) FIG. 22 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator with recovery at 1 atm.

(24) FIG. 23 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a spring-based accumulator based on various atmospheric pressures at recovery.

(25) FIG. 24 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a spring-based accumulator with recovery at 1 atm.

(26) FIG. 25 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a weight-based accumulator based on various atmospheric pressures at recovery.

(27) FIG. 26 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a weight-based accumulator with recovery at 1 atm.

DETAILED DESCRIPTION

(28) Devices, systems and methods are described herein that are configured for extracorporeal preservation and transportation of bodily tissue. Specifically, devices for monitoring and stabilizing pressure within inflated lungs are described. Systems and methods can compensate for pressure changes resulting from, for example, increases and decreases in altitude during air transport of the organ. By bleeding off and returning excess gases, volumetric expansion of the lung (i.e., over-inflation) may be prevented, avoiding damaging the organ which can result in decreased organ viability and decreased survival rates for transplant recipients. Additional aspects include contoured storage and transport chambers that can replicate the in-vivo anatomical orientation and geometry for a given organ. For example, a pair of donor lungs may be placed against a smooth, raised, central saddle designed to replicate the spine that the lungs would be resting against in vivo. Organs, such as lungs or hearts, may be suspended in an upright position to replicate the organ's orientation in a standing human and to prevent tissue damage caused by pressure from the organ's own weight resting on itself.

(29) FIG. 1 illustrates a tissue preservation and transportation system 101 according to certain embodiments. An organ adapter 107 is adapted to be coupled to the airways (e.g., by the trachea or bronchus) of a lung 103. The organ adapter 107 may comprise a lumen that, when the organ adapter 107 is coupled to the lung 103, is in fluid communication with the airways of the lung 103.

(30) The organ adapter 107 is coupled to an expandable accumulator 105 and the lumen of the organ adapter 107 is in fluid communication with a sealed interior volume of the expandable accumulator 105. The expandable accumulator 105 may be coupled by a valve 109, to an inlet 113. The inlet 113 has a lumen that, when the valve 109 is open, is in fluid communication with the interior volume of the expandable accumulator 105, the lumen of the organ adapter 107, and the airways of the lung 103. When the valve 109 is closed, the interior volume of the expandable accumulator 105, the lumen of the organ adaptor 107, and the airways of the lung 103 form an air-tight, closed environment that is sealed from the outside environment including, for example, any preservation fluid present within the organ container 111. The organ container 111 may include one or more boxes or bags configured to contain both the organ and any preservation fluid (e.g., temperature regulated, oxygenated fluid) in a sterilized environment. In preferred embodiments, the organ is placed into one or more sterile bags or boxes. For example, a lung may be placed in three concentric sterile bags fitted with a through-the-bag-wall cannula leading into the trachea plug. The cannula may include a filter for each bag (e.g., a 0.2-micron sterile filter). Accordingly, both the exterior surface and interior, pressure-dampened lumen of the organ are surrounded by three sterile layers.

(31) In various embodiments, the accumulator may have an interior volume (fully expanded) of about, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, or more liters. In preferred embodiments, the accumulator has a fully expanded interior volume of about 1 liter.

(32) System 101 is configured to permit gas to move back and forth between the airways of the lung 103 through the lumen of the organ adapter 107, and into the interior volume of the expandable accumulator 105. When the valve 109 is open, the system 101 is configured to permit gas flow from the inlet 113, through the valve 109, into the lumen of the organ adaptor 107, and finally into the airways of the lung 103. The expansion resistance of the expandable accumulator 105 may be adjustable, fixed, or progressive.

(33) The organ adapter 107 may be configured to substantially retain the bodily tissue (e.g., lung) with respect to the expandable accumulator 105. The organ adapter 107 may be configured to permit movement of a gas from the expandable accumulator 105, into the airways of the lung 103, and back. The organ adapter 107 can be configured to be coupled to a bodily tissue such as a lung 103. The organ adapter 107 can be coupled to the bodily tissue in any suitable manner For example, in some embodiments, the organ adapter 107 can configured to be sutured to the bodily tissue. In another example, the organ adapter 107 is coupleable to the bodily tissue via an intervening structure, such as silastic or other tubing. In some embodiments, at least a portion of the organ adapter 107, or the intervening structure, is configured to be inserted into the bodily tissue such as the lumen of a trachea, bronchus, or other air passage of a lung 103. For example, in some embodiments, the lumen of the organ adapter 107 (or a lumen of the intervening structure) is configured to be fluidically coupled to a lumen of the bodily tissue such as an air passage of the lung 103.

(34) In various embodiments including the use of one or more sterile bags or other containers for the organ, the organ adapter may be contained in or integral to the inner most sterile bag and coupled to a through-the-bag-wall cannula that transverses each of the bags or other containers. The cannula, at the outer most bag or other container, may include an adapter to be removably coupled to the accumulator in the systems described herein. Accordingly, the bagged organ may be easily and quickly connected to the accumulator and inflated during loading and easily and quickly disconnected upon arrival at the transplantation site.

(35) In some embodiments, the organ adapter (or simply referred as the adapter) can be configured to support the bodily tissue when the bodily tissue is coupled to the adapter. For example, in some embodiments, the adapter can include a retention mechanism (not shown) configured to be disposed about at least a portion of the bodily tissue and to help retain the bodily tissue with respect to the adapter. The retention mechanism can be, for example, a net, a cage, a sling, or the like. In some embodiments, the system can include a basket (not shown) or other support mechanism configured to support the bodily tissue when the bodily tissue is coupled to the adapter or otherwise received in the system. The organ adapter may be rigidly coupled to an interior wall (e.g. a lid) of an organ container such that the organ may be suspended via its connection point to the adapter.

(36) The portion of the adapter that is inserted into a lumen of the organ may include a series of tapered steps such that a distal end of the adapter portion is narrower than a proximal end. In this manner, the adapter is configured to be inserted into a range of lumen sizes.

(37) The lumen may be secured or sealed to the organ adapter via any means including elastic tension in the organ lumen itself or through the use of sutures, elastic band, or other securing mechanisms on the outside of the lumen applying pressure thereupon to form an air-tight seal between the lumen of the organ and the lumen of the adapter.

(38) The expandable accumulator is configured to expand to accept relative increases in gas volume within the closed system in response to pressure differential changes between the closed system and the surrounding environment (e.g., during flight). The interior volume of the expandable accumulator should resist expansion with an opposing force that is less than that of the lung. Accordingly, decreases in internal pressure of the closed system due to decreases in the pressure of the surrounding environment (e.g. during flight) will be borne by the expandable accumulator such that the pressure within the system drops without volumetric expansion of the lung airways (which could cause tissue damage or rupture the airways).

(39) The expandable accumulator is configured to be in constant communication with the internal (closed system) pressure and the external (surrounding environment) pressure, and to establish a nearly-constant differential between the two while having compliance higher than the lung's compliance. The pressure differential is such that the internal pressure is greater than the environment pressure. The pressure differential keeps the lungs inflated. The pressure differential would commonly be referred to as the gauge pressure. When the system is initially prepared, the external pressure may be 1 bar (absolute) and the internal pressure would be 1+x bar, absolute (where the x is a suitable value chosen for best storage performance). The gauge pressure of the closed system is therefore x bar, and the differential pressure across the lung is also x bar. At a later time, in transport, the external pressure may be 0.75 bar for instance due to airplane cabin pressure when in flight. The internal pressure would be 0.75+x bar, so the gauge pressure is again x bar, as is the pressure across the lung. In this manner the expandable accumulator maintains a nearly-constant pressure differential across the lung (from inside to outside).

(40) In order to maintain the nearly-constant pressure differential the expandable accumulator will have a very high compliance, for example much higher than the lung compliance. In certain embodiments, the system may be configured to maintain about a 15 cm H.sub.2O gauge pressure inside the organ. The pressure may be fixed or may be tunable or adjustable using variable weight, spring tension, or other means depending on the accumulator mechanism. Pressure in the system may be set by filling the system to a desired fixed pressure or may be controlled using an adjustable accumulator which may be acted on by a computer based on inputs received from a pressure or other sensor as described below.

(41) An inlet of the system may be used to add or remove a gas from the lumen of the organ (e.g., airways of a lung). For example, where donor lungs are at least partially inflated for storage and transport, a retrieved lung may be secured to an organ adapter as shown in FIGS. 1-6. The inlet may be then connected to a gas source such as a compressed air tank or a source of oxygen or another gas or combinations thereof. In certain embodiments, the gas source may comprise a pump or bulb for manually filling the system with ambient air or other gas. The pump or bulb may be integral to the transport container and travel with the container or may be used to establish pressure and removed after a valve located between the pump or bulb and the organ is closed. The valve connecting the inlet to the closed system of the lung airways, lumen of the adapter, and interior volume of the expandable accumulator may then be opened and oxygen or another gas or mixture of gasses may then be allowed to flow into the closed system. In certain embodiments (e.g., lung transport), gasses such as oxygen may damage the tissue and, as such, the fill gas will be selected accordingly (e.g., ambient air). The closed system may be inflated to a desired pressure which may be monitored with a pressure gauge or sensor located on the gas source or on the closed system. The pressure sensor may be electric and include a wireless sender located on the closed system such that pressure may be wirelessly monitored from outside an organ transport container during transport.

(42) During inflation, as gas is admitted to the system, both the lungs and the expandable accumulator will inflate until reaching the desired gauge pressure (designated “x” above). As additional gas is thereafter admitted, the gas would preferentially fill the expandable accumulator given that component's higher compliance. When the expandable accumulator is entirely filled, the pressure would begin to rise above the “x” target, and the system would not have any remaining capacity. Therefore, when the system is filled the volume of gas may be adjusted such that a movable element of the expandable accumulator rests at a target position (for instance 25% of travel). Once the expandable accumulator is at that target position, the valve can be closed and the closed system is sealed and ready for transport.

(43) Once the lung has been inflated to a desired pressure, the valve may be closed, sealing off the closed system. The lung coupled to the expandable accumulator by the organ adapter along with the closed valve and the inlet may be then be placed in an organ container for storage or transport and may be at least partially submerged in a fluid such as a preservation fluid as known in the art. Examples of preservation fluid and static and perfusion-based tissue containers compatible with systems and methods of the invention are described in U.S. application Ser. No. 14/460,489, incorporated herein by reference.

(44) The fill of the accumulator can be adjusted at organ recovery according to the local ambient (e.g. barometric) pressure. A smaller accumulator would thereby be able to work identically whether filled in Denver CO, or Boston Mass., whatever the weather conditions. The accumulator may include a scale or other indicator in customary barometric pressure units. An exemplary pressure indicator 1115 is shown in FIGS. 11, 14, 15, and 19. An ambient pressure sensor or meter may also be included for reading ambient pressure at recovery. The system may then be filled until the piston reaches a mark on the scale or indicator on the accumulator that matches the local barometric pressure reading. If not adjusted to local pressure conditions, a larger accumulator may be used.

(45) The expandable accumulator may be of any configuration that permits expansion of its interior volume with less resistance than that of the lung's airways. Examples of expandable accumulators are shown in FIGS. 1-6. Materials for transport and storage containers of the invention may be selected to reduce weight in key components such as the accumulator. For example, accumulators such as the rolling diaphragm types depicted in FIGS. 3 and 4 may comprise a piston that slides within a cylinder to adjust volume to dampen pressure changes in the tissue. The piston or other accumulator components may be constructed of lightweight materials such as aluminum, plastics, or carbon fiber or may be constructed with lightweight techniques including low material thickness with structural bracing for example. Reducing the weight or mass of the moving pieces of the accumulator helps to minimize pressure changes resulting from movement (e.g., tilting) of the container or accumulator therein. Pressure generating force is thereby primarily established by an accumulator spring and relatively unaffected by gravity.

(46) The expandable accumulator 105 depicted in FIG. 1 comprises a bellows-type interior bladder that permits expansion. The bellows may be contained within a shell that may be rigid to preserve an open interior volume into which the bellows can expand. The bellows may rely on inherent shape memory in the material of the bellows itself to provide resistance to expansion or may use, for example, springs opposing the expansion of the bellows via compression or tension. Any known spring type may be used including coiled materials or elastic bands to provide expansion resistance. The spring rate can be selected such that the expansion resistance provided to the interior volume of the accumulator is less than the expansion resistance of the lung's airways. The expansion resisting force may be a single rate or may be progressive or adjustable. The expansion resisting force can be modeled on the expansion resistance profile of lung airways in order to better maintain a constant pressure within the lung. In various embodiments, a constant force spring can be used to maintain internal pressure. Constant force springs are springs for which the force they exert over their range of motion is relatively constant. Constant force springs may be constructed from rolled ribbons of, for example, spring steel. In certain embodiments, the springs used in the systems depicted in FIGS. 3 and 4 may be constant force springs. In some embodiments, a pair of constant force springs may be used in a back-to-back orientation.

(47) FIG. 2 shows a system 201 including a lung 203, an organ adapter 207, an expandable accumulator 205, a valve 209, and an inlet 213 all placed within an organ container 211. The components are configured and relate to each other in a similar manner to that shown in FIG. 1 aside from differences in the operation of the expandable accumulator 205. The expandable accumulator 205 comprises a bellows type accumulator 205 that is not contained in a shell such that the outer surface of the expandable accumulator 205 is in direct communication with the interior environment of the organ container 211. The expandable accumulator 205 may provide expansion resistance through its own material properties or through applied force from, for example, a spring.

(48) FIG. 3 shows a system 301 including a lung 303, an organ adapter 307, an expandable accumulator 305, a valve 309, and an inlet 313 all placed within an organ container 311. The components are configured and relate to each other in a similar manner to that shown in FIG. 1 aside from differences in the operation of the expandable accumulator 305. The expandable accumulator 305 comprises a rolling diaphragm and a spring in compression to provide expansion resistance.

(49) The rolling diaphragm contributes to a low-friction, low-hysteresis accumulator advantageous to tissue preservation as described herein, especially in lung preservation and transport apparatuses. The diaphragm may be constructed of any suitable material including latex, rubber, or silicon.

(50) FIG. 4 shows a system 401 including a lung 403, an organ adapter 407, an expandable accumulator 405, a valve 409, and an inlet 413 all placed within an organ container 411. The components are configured and relate to each other in a similar manner to that shown in FIG. 3 aside from differences in the operation of the expandable accumulator 405. The expandable accumulator 405 comprises a rolling diaphragm and a spring in tension to provide expansion resistance.

(51) A diaphragm-type accumulator system as exemplified in FIGS. 3 and 4 may use a constant force spring to maintain a constant internal pressure in the lung or other organ. The diaphragm may be coupled to one or more springs in tension, compression, or some combination thereof (e.g., two opposing springs coupled to the diaphragm and providing expansion resistance through both compression and tension).

(52) FIG. 5 shows a system 501 including a lung 503, an organ adapter 507, an expandable accumulator 505, a valve 509, and an inlet 513 all placed within an organ container 511. The components are configured and relate to each other in a similar manner to that shown in FIG. 1 aside from differences in the operation of the expandable accumulator 205. The expandable accumulator 505 comprises a balloon-type bladder wherein expansion resistance is provided by the elasticity of the material comprising the walls of the expandable accumulator 505. As shown in FIG. 5, the lungs 503 are suspended in a vertical orientation from the organ adapter 507 providing the benefits described above.

(53) FIG. 6 shows a system 601 including a lung 603, an organ adapter 607, an expandable accumulator 605, a valve 609, and an inlet 613 all placed within an organ container 611. The components are configured and relate to each other in a similar manner to that shown in FIG. 1 aside from differences in the operation of the expandable accumulator 605. The expandable accumulator 105 depicted in FIG. 1 comprises a bellows-type interior bladder that permits expansion. The bellows may be contained within a shell that may be rigid to preserve an open interior volume into which the bellows can expand. The bellows may rely on inherent shape memory in the material of the bellows itself to provide resistance to expansion or may use, for example, gravity to provide the expansion resistance through a weight 615 placed on top of the bellows.

(54) As noted, systems of the invention are compatible with and may include any static or perfusion-type preservation apparatus. An example of such a configuration is shown in FIG. 7. An apparatus 10 is shown configured to oxygenate a perfusate (not shown) received in a pumping chamber 14 of the apparatus. The apparatus 10 includes a valve 12 configured to permit a fluid (e.g., oxygen) to be introduced into a first portion 16 of the pumping chamber 14. A membrane 20 is disposed between the first portion 16 of the pumping chamber 14 and a second portion 18 of the pumping chamber. The membrane 20 is configured to permit the flow of a gas between the first portion 16 of the pumping chamber 14 and the second portion 18 of the pumping chamber through the membrane. The membrane 20 is configured to substantially prevent the flow of a liquid between the second portion 18 of the pumping chamber 14 and the first portion 16 of the pumping chamber through the membrane. In this manner, the membrane can be characterized as being semi-permeable.

(55) The membrane 20 is disposed within the pumping chamber 14 along an axis Al that is transverse to a horizontal axis A2. Said another way, the membrane 20 is inclined, for example, from a first side 22 to a second side 24 of the apparatus 10. As such, as described in more detail below, a rising fluid in the second portion 18 of the pumping chamber 14 will be directed by the inclined membrane 20 towards a port 38 disposed at the highest portion of the pumping chamber 14. The port 38 is configured to permit the fluid to flow from the pumping chamber 14 into the atmosphere external to the apparatus 10. In some embodiments, the port 38 is configured for unidirectional flow, and thus is configured to prevent a fluid from being introduced into the pumping chamber 14 via the port (e.g., from a source external to the apparatus 10). In some embodiments, the port 38 includes a luer lock.

(56) The second portion 18 of the pumping chamber 14 is configured to receive a fluid. In some embodiments, for example, the second portion 18 of the pumping chamber 14 is configured to receive a liquid perfusate. The second portion 18 of the pumping chamber 14 is in fluid communication with an adapter 26. The adapter 26 is configured to permit movement of the fluid from the pumping chamber 14 to a bodily tissue T. For example, in some embodiments, the pumping chamber 14 defines an aperture (not shown) configured to be in fluidic communication with a lumen (not shown) of the adapter 26. The adapter 26 is configured to be coupled to the bodily tissue T. The adapter 26 can be coupled to the bodily tissue T in any suitable manner For example, in some embodiments, the adapter 26 is configured to be sutured to the bodily tissue T. In another example, the adapter 26 is coupleable to the bodily tissue T via an intervening structure, such as silastic or other tubing. In some embodiments, at least a portion of the adapter 26, or the intervening structure, is configured to be inserted into the bodily tissue T. For example, in some embodiments, the lumen of the adapter 26 (or a lumen of the intervening structure) is configured to be fluidically coupled to a vessel of the bodily tissue T.

(57) Where the tissue T is, for example a lung, the airways of the tissue T may be coupled to an expandable accumulator 705 and associated systems as described herein via an organ adapter 707 (e.g., via the trachea or bronchus).

(58) In some embodiments, the adapter 26 is configured to support the bodily tissue T when the bodily tissue T is coupled to the adapter. For example, in some embodiments, the adapter 26 includes a retention mechanism (not shown) configured to be disposed about at least a portion of the bodily tissue T and to help retain the bodily tissue T with respect to the adapter. The retention mechanism can be, for example, a net, a cage, a sling, or the like. In some embodiments, the apparatus 10 includes a basket (not shown) or other support mechanism configured to support the bodily tissue T when the bodily tissue T is coupled to the adapter 26 or otherwise received in the apparatus 10.

(59) An organ chamber 30 is configured to receive the bodily tissue T and a fluid. In some embodiments, the apparatus 10 includes a port 34 that is extended through the apparatus 10 (e.g., through the pumping chamber 14) to the organ chamber 30. The port 34 is configured to permit fluid (e.g., perfusate) to be introduced to the organ chamber 30. In this manner, fluid can be introduced into the organ chamber 30 as desired by an operator of the apparatus. For example, in some embodiments, a desired amount of perfusate is introduced into the organ chamber 30 via the port 34, such as before disposing the bodily tissue T in the organ chamber 30 and/or while the bodily tissue T is received in the organ chamber. In some embodiments, the port 34 is a unidirectional port, and thus is configured to prevent the flow of fluid from the organ chamber 30 to an area external to the organ chamber through the port. In some embodiments, the port 34 includes a luer lock. The organ chamber 30 may be of any suitable volume necessary for receiving the bodily tissue T and a requisite amount of fluid for maintaining viability of the bodily tissue T. In one embodiment, for example, the volume of the organ chamber 30 is approximately 2 liters.

(60) The organ chamber 30 is formed by a canister 32 and a bottom portion 19 of the pumping chamber 14. In a similar manner as described above with respect to the membrane 20, an upper portion of the organ chamber (defined by the bottom portion 19 of the pumping chamber 14) can be inclined from the first side 22 towards the second side 24 of the apparatus. In this manner, as described in more detail below, a rising fluid in the organ chamber 30 will be directed by the inclined upper portion of the organ chamber towards a valve 36 disposed at a highest portion of the organ chamber. The valve 36 is configured to permit a fluid to flow from the organ chamber 30 to the pumping chamber 14. The valve 36 is configured to prevent flow of a fluid from the pumping chamber 14 to the organ chamber. The valve 36 can be any suitable valve for permitting unidirectional flow of the fluid, including, for example, a ball check valve.

(61) The canister 32 can be constructed of any suitable material. In some embodiments, the canister 32 is constructed of a material that permits an operator of the apparatus 10 to view at least one of the bodily tissue T or the perfusate received in the organ chamber 30. For example, in some embodiments, the canister 32 is substantially transparent. In another example, in some embodiments, the canister 32 is substantially translucent. The organ chamber 30 can be of any suitable shape and/or size. For example, in some embodiments, the organ chamber 30 can have a perimeter that is substantially oblong, oval, round, square, rectangular, cylindrical, or another suitable shape.

(62) In use, the bodily tissue T is coupled to the adapter 26. The pumping chamber 14 is coupled to the canister 32 such that the bodily tissue T is received in the organ chamber 30. In some embodiments, the pumping chamber 14 and the canister 32 are coupled such that the organ chamber 30 is hermetically sealed. A desired amount of perfusate is introduced into the organ chamber 30 via the port 34. The organ chamber 30 can be filled with the perfusate such that the perfusate volume rises to the highest portion of the organ chamber. The organ chamber 30 can be filled with an additional amount of perfusate such that the perfusate flows from the organ chamber 30 through the valve 36 into the second portion 18 of the pumping chamber 14. The organ chamber 30 can continue to be filled with additional perfusate until all atmospheric gas that initially filled the second portion 18 of the pumping chamber 14 rises along the inclined membrane 20 and escapes through the port 38. Because the gas will be expelled from the pumping chamber 14 via the port 38 before any excess perfusate is expelled (due to gas being lighter, and thus more easily expelled, than liquid), an operator of the apparatus 10 can determine that substantially all excess gas has been expelled from the pumping chamber when excess perfusate is released via the port. As such, the apparatus 10 can be characterized as self-purging. When perfusate begins to flow out of the port 38, the apparatus 10 is in a “purged” state (i.e., all atmospheric gas initially within the organ chamber 30 and the second portion 18 of the pumping chamber 14 has been replaced by perfusate). When the purged state is reached, the operator can close both ports 34 and 38, preparing the apparatus 10 for operation.

(63) Oxygen (or another suitable fluid, e.g., gas) is introduced into the first portion 16 of the pumping chamber 14 via the valve 12. A positive pressure generated by the introduction of oxygen into the pumping chamber 14 causes the oxygen to be diffused through the semi-permeable membrane 20 into the second portion 18 of the pumping chamber. Because oxygen is a gas, the oxygen expands to substantially fill the first portion 16 of the pumping chamber 14. As such, substantially the entire surface area of the membrane 20 between the first portion 16 and the second portion 18 of the pumping chamber 14 is used to diffuse the oxygen. The oxygen is diffused through the membrane 20 into the perfusate received in the second portion 18 of the pumping chamber 14, thereby oxygenating the perfusate.

(64) In the presence of the positive pressure, the oxygenated perfusate is moved from the second portion 18 of the pumping chamber 14 into the bodily tissue T via the adapter 26. For example, the positive pressure can cause the perfusate to move from the pumping chamber 14 through the lumen of the adapter 26 into the vessel of the bodily tissue T. The positive pressure is also configured to help move the perfusate through the bodily tissue T such that the bodily tissue T is perfused with oxygenated perfusate.

(65) After the perfusate is perfused through the bodily tissue T, the perfusate is received in the organ chamber 30. In this manner, the perfusate that has been perfused through the bodily tissue T is combined with perfusate previously disposed in the organ chamber 30. In some embodiments, the volume of perfusate received from the bodily tissue T following perfusion combined with the volume of perfusate previously disposed in the organ chamber 30 exceeds a volume (e.g., a maximum fluid capacity) of the organ chamber 30. A portion of the organ chamber 30 is flexible and expands to accept this excess volume. The valve 12 can then allow oxygen to vent from the first portion 16 of the pumping chamber 14, thus, reducing the pressure in the pumping chamber 14. As the pressure in the pumping chamber 14 drops, the flexible portion of the organ chamber 30 relaxes, and the excess perfusate is moved through the valve 36 into the pumping chamber 14. The cycle of oxygenating perfusate and perfusing the bodily tissue T with the oxygenated perfusate can be repeated as desired.

(66) FIGS. 8A and 8B show an organ container 811 comprising a smooth raised portion 815 or saddle disposed on an interior wall of the organ container and designed to mimic the shape of the spine to replicate the in vivo environment of lungs being stored or transported. Such organ containers 811 are compatible with any other systems described herein including perfusing or static storage containers and various pressure regulating systems. FIG. 9 shows positioning of a pair of donor lungs 915 on a raised center portion 915 of an organ container 911 intended to mimic the spine in the lungs' in vivo environment.

(67) The interior of organ containers of the invention may contain a fixed or removable shelf or tray configured to support cooling materials (e.g., frozen gel packs). Such a tray allows the organ to be loaded into the container before the tray is in place and, once the tray is inserted, the tray supports the cooling materials keeping them proximate to the organ for cooling purposes but prevents the materials from contacting the organ which can cause damage thereto. The tray may further serve to locate the organ within the colder bottom portion of the container.

(68) FIGS. 10A and 10B show an organ adapter 1007 configured for insertion into the trachea of a donor lung to be transported using a tissue preservation and transportation system as described above. The organ adapter 1007 may taper as shown in FIGS. 10A and 10B to form an air-tight seal against the interior surface of the trachea or other organ opening to be transported and may include ridges 1017 to aid retention of the adapter 1007 within the organ opening once inserted. The organ adapter 1007 includes tubing 1015 for connecting to an expandable accumulator as described above and includes an inner lumen 1019 for providing fluid communication between the accumulator and the interior of the organ. Once inserted into the organ, the organ adapter 1007, interior space of the organ, and the accumulator form a closed, air-tight system.

(69) Systems of the invention may include a variety of sensors configured to sense and report, for example, temperature of the tissue, temperature of a preservation fluid or perfusate, pressure within the closed air system, pressure within the fluid, or ambient pressure. Displays for the sensors may be disposed on the outer surfaces of the organ transport or may be wirelessly linked to the internal sensors.

(70) In some embodiments, a temperature sensor may include a probe positioned in the transport cavity and attached by a flexible cable to a temperature datalogger. The probe may not be wetted (i.e., the probe would remain outside of any sterile bags or containers) and may be suspended in air by a bracket or support in order to avoid direct contact with any cooling materials. The probe would thereby record and/or report the cavity temperature rather than the lung tissue temperature.

(71) In certain embodiments, the sensor may comprise a mechanical flag that indicates the furthest expansion of the expandable accumulator and can therefore indicate if the accumulator reached maximum expansion presenting the possibility that additional pressure was absorbed by the lung tissue through over-inflation.

(72) FIG. 11 shows an exemplary organ container 1101 with an accumulator 1105 having an accumulator scale 1115 to indicate barometric pressure. As noted above, the indicator may be used by technicians when adjusting the accumulator to local pressure conditions. The organ container 1101 may include a recess, port, or other feature for retaining the accumulator 1105, preferably, as shown in FIG. 11, in a position that allows for external monitoring of the accumulator 1105. The organ container may include wheels and an extendable handle as shown for ease of transport and storage.

(73) FIG. 12 shows an exploded view of an exemplary organ container 1101. The organ container 1101 features an accumulator 1105, a gas source 1113 (e.g., a bulb) for pressurizing the system, and an organ adapter 1107 (e.g., a trachea plug) for interfacing an organ with the system. The organ container 1101 also includes tubing 1111 or connectors for coupling the gas source 1113 and the organ adapter 1107 to the accumulator 1105. The organ container 1101 may also use a valve 1109 (e.g., a roller clamp) operable to regulate fluid communication between the gas source 1113 and the accumulator 1105 by, for example, acting on the tubing 1111.

(74) FIG. 13 shows a cross-sectional view of an exemplary organ container 1101 illustrating an exemplary configuration of various components described herein including an accumulator 1105 an organ adapter 1107 (not coupled to an organ) and connecting tubing 1111. A sensor 1117 (e.g., a temperature sensor) as described above, is also included at the bottom of the organ camber and, while potentially wireless in some embodiments, is depicted in FIG. 13 in a wired format in electronic communication with an external display 1119 (e.g., an LCD screen) to display data obtained from the sensor 1117. An organ such as a lung would rest on the bottom of the cavity.

(75) FIG. 14 shows an external view of an open organ container 1101 with an accumulator 1105 according to certain embodiments. With the lid removed from the exemplary organ container 1101, it is ready to accept or deliver an organ. The accumulator 1105 with a pressure indicator 1115 is shown placed in a fitted receptacle on the organ container 1101. A gas source 1113 is connected by tubing 1111 to the accumulator 1105 and that connection is regulated by a valve 1109. The organ container 1101 also features a storage pocket 1121 for receiving and storing the gas source 1113, valve 1109, and tubing 1111 when not in use. The illustrated organ container 1101 does not have an organ loaded and so the organ adapter 1107 inside the cavity is seen.

(76) FIG. 15 shows an external view of an open organ container 1101 with an accumulator 1105 with pressure indicator 1115. A tray 1123 is adapted to be positioned above a loaded organ in the cavity of the organ container 1101 to hold cooling materials such as frozen gel packs off of the organ tissue surface. The tray may be supported by, for example, indentions in the interior walls of the cavity. The gas source 1113 is shown stored in the storage pocket 1121 for transport.

(77) FIG. 16A shows a transverse cross-sectional view of an approximately empty accumulator 1105 according to certain embodiments and FIG. 16B shows a lateral cross-sectional view. The accumulator 1105 includes a piston 1125 and a rolling diaphragm 1127 as described above. As seen in FIG. 16B, a pair of back-to-back constant force springs 1129 comprising rolled ribbons of, for example, spring steel.

(78) FIG. 17 shows a lateral cross-sectional view of an approximately half full accumulator 1105 and FIG. 18 shows a lateral cross-sectional view of an approximately full accumulator 1105. As seen in FIGS. 16B-18, as the accumulator 1105 is filled or expands, the rolling diaphragm 1127 unfolds while the ribbons of the constant force springs 1129 unwind thereby providing resistance against said expansion. As noted earlier, the rolling diaphragm 1127 helps maintain a seal between the outer surface of the piston 1125 and the inner wall of the accumulator 1105 while minimizing friction between the two surfaces that might interfere with the expansion or operation of the accumulator 1105.

(79) FIG. 19 shows an exploded view of an accumulator 1105. The outer barrel of the accumulator 1105 may be constructed of a material such as polycarbonate plastic and is preferably transparent enough for the position of the piston 1125 therein to be externally readable against a pressure indicator 1115 on the accumulator 1105. For example, the top edge of the piston 1125 may align with a mark on the pressure indicator 1115 to indicate a pressure setting. A clear outer barrel may also allow for monitoring of the state of the piston 1125 within the accumulator 1105 during transport to observe, for example, a maximum displacement thereof. FIG. 19 shows a pair of constant force springs 1129 and a pair of connectors 1131 configured to couple to tubing to provide fluid communication between the interior of the accumulator 1105 and a gas source and an organ via an organ adapter.

(80) As one skilled in the art would recognize as necessary or best-suited for the systems and methods of the invention, systems and methods of the invention may include computers that may include one or more of processor (e.g., a central processing unit (CPU), a graphics processing unit (GPU), etc.), computer-readable storage device (e.g., main memory, static memory, etc.), or combinations thereof which communicate with each other via a bus. Computers may include mobile devices (e.g., cell phones), personal computers, and server computers. In various embodiments, computers may be configured to communicate with one another via a network in order to display image series or allow remote storage, viewing, or selection of images of a given series.

(81) A processor may include any suitable processor known in the art, such as the processor sold under the trademark XEON E7 by Intel (Santa Clara, Calif.) or the processor sold under the trademark OPTERON 6200 by AMD (Sunnyvale, Calif.).

(82) Memory preferably includes at least one tangible, non-transitory medium capable of storing: one or more sets of instructions executable to cause the system to perform functions described herein (e.g., software embodying any methodology or function found herein); data (e.g., portions of the tangible medium newly re-arranged to represent real world physical objects of interest accessible as, for example, a picture of an object like a motorcycle); or both. While the computer-readable storage device can in an exemplary embodiment be a single medium, the term “computer-readable storage device” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the instructions or data. The term “computer-readable storage device” shall accordingly be taken to include, without limit, solid-state memories (e.g., subscriber identity module (SIM) card, secure digital card (SD card), micro SD card, or solid-state drive (SSD)), optical and magnetic media, hard drives, disk drives, and any other tangible storage media.

(83) Input/output devices according to the invention may include one or more of a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT) monitor), an alphanumeric input device (e.g., a keyboard), any temperature, pressure, or other sensor described herein, a cursor control device (e.g., a mouse or trackpad), a disk drive unit, a signal generation device (e.g., a speaker), a touchscreen, a button, an accelerometer, a microphone, a cellular radio frequency antenna, a network interface device, which can be, for example, a network interface card (NIC), Wi-Fi card, or cellular modem, or any combination thereof.

(84) One of skill in the art will recognize that any suitable development environment or programming language may be employed to allow the operability described herein for various systems and methods of the invention. For example, systems and methods herein can be implemented using Perl, Python, C++, C#, Java, JavaScript, Visual Basic, Ruby on Rails, Groovy and Grails, or any other suitable tool. For a computer, it may be preferred to use native xCode or Android Java.

EXAMPLES

Example 1 Modeling of Lung Pressure Changes During Transport

(85) Lung volume and pressure conditions were modeled during transport without an accumulator, with a spring-based accumulator, and with a weight based accumulator (as described above). Since PV=nRT (ideal gas law) the trapped volume inside the lung will obey pV/T=constant or p.sub.f V.sub.f/T.sub.f=p.sub.o V.sub.o/T.sub.o where “o” refers to starting and “f” to final conditions.

(86) P is the atmospheric pressure, absolute. p is the internal pressure, absolute, biased somewhat above P. V is the contained volume (lung, tubing, accumulator) T is the temperature in Kelvin.

(87) For pressure the model defines and uses cmH.sub.2O and atm (the SI unit standard). Pressure measurements are absolute unless otherwise stated.

(88) $\mathrm{cmH}2O\equiv \frac{\mathrm{gm}.Math.g}{{\mathrm{cm}}^2}1\mathrm{atm}=1.033\times {10}^3.Math.\mathrm{cmH}2O1\mathrm{atm}=14.696.Math.\mathrm{psi}$
Ambient Condition Ranges:

(89) Ambient Pressure (P) can range between the following (note that weather measurements are usually in inHg)
1atm=29.921in_HgPatm.sub.min=25.69in_Hg=0.899atmPatm.sub.max:=32.06in_Hg=1.071atm
Altitude at recovery should be accounted for. For example, the typical pressure in a city such as Denver, Colo. may be calculated as:

(90) $P_{\mathrm{atmosphere}}\left(h\right)\text{:}=1\mathrm{atm}.Math.\exp \left(\frac{-g.Math.0.0289644\frac{\mathrm{kg}}{\mathrm{mol}}.Math.h}{8.31447\frac{J}{K.Math.\mathrm{mol}}.Math.288.15K}\right)P_{\mathrm{atmosphere}}\left(5280\mathrm{ft}\right)=0.826.Math.\mathrm{atm}$
The range of P.sub.o is from ˜0.8 to ˜1.08 atm. Lung temperature (T) can range between the following (assumes that recovery occurs in cold operating rooms and transport is under not as cold conditions):
T.sub.o_min:=2° C.=275.15K and T.sub.o_max:=65° F.=291.483K
Travel Conditions:

(91) To model transit conditions, it is assumed that T stays approximately constant. Allowing T.sub.f to rise to 8° C. is conservative. Extremes of pressure will be seen in airplane cabins and is approximated as follows for various aircraft (Cabin Pressure is typically measured in equivalent altitude):

(92) Regulatory Maximum=2400 m (p.sub.atmosphere(2400 m)=0.752 atm)

(93) Boeing 767=2100 m (p.sub.atmosphere(2100 m)=0.780 atm) (typical of older airliners)

(94) Airbus A380=1868 m (p.sub.atmosphere(1868 m)=0.801 atm)

(95) Boeing 747-400=1572 m (p.sub.atmosphere(1572 m)=0.830 atm)

(96) So flight pressures can range from 0.752 up to 0.830 atm.

(97) Range Values for Exploring Solution Space:

(98) i:=0 . . . 50 (where i is the ambient pressure index); j:=0 . . . 2 (where j is the initial conditions index for solutions of multiple cases simultaneously); P.sub.min:=0.75 atm and P.sub.max:=1.10 atm

(99) $P_{{\mathrm{travel}}_1}\text{:}=P_{\min }+\frac{\left(P_{\max }-P_{\min }\right)}{50}.Math.1$
Lung Parameters:

(100) The lung values used herein are taken from literature. The volumes at 40 cmH.sub.2O and above are extrapolated. The resulting interpolated lung pressure-volume model is large: volume is 4.74 liters at 15 cmH2O. The pressure-volume model was scaled to establish a resting volume of 3.5 L at 15 cmH2O.″

(101) ${\mathrm{Lung}}_p:=\left[\begin{array}{c}-20\\ -16\\ -12\\ -8\\ -4\\ 0\\ 4\\ 8\\ 12\\ 16\\ 20\\ 24\\ 28\\ 32\\ 36\\ 40\\ 50\\ 60\\ 70\\ 85\\ 100\end{array}\right]\mathrm{cm}H2O{\mathrm{Lung}}_v:=\left[\begin{array}{c}0.600\\ 0.635\\ 0.670\\ 0.695\\ 0.710\\ 0.815\\ 1.100\\ 2.400\\ 3.900\\ 4.600\\ 5.040\\ 5.250\\ 5.370\\ 5.470\\ 5.500\\ 5.525\\ 5.543754952\\ 5.557634961\\ 5.567219684\\ 5.572870767\\ 5.574845677\end{array}\right]L$

(102) V.sub.rest:=3.5 L; P.sub.rest:=15 cmH.sub.2O

(103) LungV (p, P):=interp[1spline(Lung.sub.p, Lung.sub.v), Lung.sub.p, Lung.sub.v, (p-P)]

(104) LungV(P.sub.rest, 0 cmH2O)=4.474 L

(105) Vlung.sub.max=5 L (this simulates a volume constraint from a perfectly rigid lung) The scaled, max-limited Lung Volume formula is then:

(106) $V_{\mathrm{lung}}\left(p,P\right)\text{:}=\min \left({\mathrm{Vlung}}_{\max }\mathrm{Lung}V\left(p,P\right).Math.\frac{V_{\mathrm{rest}}}{\mathrm{Lung}V\left(P_{\mathrm{rest}},0\mathrm{cmH}2O\right)}\right)$

(107) (where =internal and P =external pressure, absolute)

(108) A graph of the lung curve can be modeled using the following equation:

(109) $\Delta {\mathrm{Plung}}_{\min }\text{:}=\min \left({\mathrm{Lung}}_p\right)=-20.Math.\mathrm{cmH}2O$$\Delta {\mathrm{Plung}}_{\max }\text{:}=\max \left({\mathrm{Lung}}_p\right)=100.Math.\mathrm{cmH}2O$$\Delta {\mathrm{Plung}}_i\text{:}=\Delta {\mathrm{Plung}}_{\min }+\frac{\left(\Delta {\mathrm{Plung}}_{\max }-\Delta {\mathrm{Plung}}_{\min }\right)}{50}.Math.i$

(110) A graph of the target volume, pressure and target compliance can be created as follows:

(111) $K_{\mathrm{target}}\text{:}=\frac{200\mathrm{mL}}{\mathrm{cmH}2O}$$\mathrm{Target}\mathrm{Line}Y\text{:}=\left(\begin{array}{c}10L\\ V_{\mathrm{rest}}\\ -1L\end{array}\right)$$\mathrm{Target}\mathrm{Line}X\text{:}=\left[\begin{array}{c}{P}_{\mathrm{rest}}+\frac{\left(\mathrm{Target}{\mathrm{LineY}}_0-V_{\mathrm{rest}}\right)}{K_{\mathrm{target}}}\\ P_{\mathrm{rest}}\\ P_{\mathrm{rest}}+\frac{\left(\mathrm{Target}{\mathrm{LineY}}_2-V_{\mathrm{rest}}\right)}{K_{\mathrm{target}}}\end{array}\right]$

(112) The curve of an ex-vivo lung model, volume vs. pressure is shown in FIG. 20. The target shown is a lung volume of 3.5 L at 15 cmH2O. The curve is taken from literature and scaled (on Yaxis) to pass through target. Values for pressure>36 cmH2O are extrapolated.

(113) Accumulator parameters for the model were varied based on the accumulator used as follows:

(114) 1) No Accumulator:

(115) AccumPresent=0(When this is zero, there's no accumulator in the system).

(116) Vacm1tr.sub.min=50 mL Vacm1tr.sub.max=1500.0 mL (These values represent the designed volume range)

(117) $\begin{array}{cc}{\mathrm{Vacmltr}}_{\mathrm{recovery}}=\left(\begin{array}{c}1.000\\ 0.350\\ 0.050\end{array}\right).Math.L& \end{array}$
(this is set by the recovery team, e.g. system is filled with air until accumulator is at the stipulated volume, which may vary based on ambient pressure at time/place of recovery)

(118) $\mathrm{Kacmltr}=400.0.Math.\frac{\mathrm{mL}}{\mathrm{cmH}2O}$
(Higher numbers here represent a weight-loaded design; lower numbers represent a spring-loaded design)
ΔP.sub.acm1tr=15.Math.cmH2O

(119) (This is the nominal accumulator pressure, at Vacm1tr.sub.recovery1, e.g., when the piston is at the target volume for the nominal pressure case. It is set by the weight or spring)

(120) 0$V_{\mathrm{acmltr}}\left(p,P\right)\text{:}=\max [{\mathrm{Vacmltr}}_{\min },\min \left[{\mathrm{Vacmltr}}_{\max },{\mathrm{Vacmltr}}_{{\mathrm{recovery}}_1}+\hspace{1em}\mathrm{Kacmltr}\left(p-P-{\mathrm{\Delta P}}_{\mathrm{acmltr}}\right)]\right]{\mathrm{Hacmltr}}_{\max }\text{:}=20\mathrm{cm}{\mathrm{Hacmltr}}_{\max }\text{:}=7.874\mathrm{in}\mathrm{Dacltr}\text{:}=\sqrt{\frac{4{\mathrm{Vacmltr}}_{\max }}{\pi {\mathrm{Hacmltr}}_{\max }}}=9.772.Math.\mathrm{cm}{\mathrm{Fspring}}_{\max }\text{:}=\Delta P_{\mathrm{acmltr}}\frac{\pi }{4}.Math.{\mathrm{Dacltr}}^2=2.48.Math.\mathrm{lbf}{\mathrm{Fspring}}_{\max }\text{:}={\mathrm{Fspring}}_{\min }+\frac{\left({\mathrm{Vacmltr}}_{\max }-{\mathrm{Vacmltr}}_{\min }\right)}{\mathrm{Kacmltr}}.Math.\left(\frac{\pi }{4}.Math.{\mathrm{Dacltr}}^2\right)=3.08.Math.\mathrm{lbf}\mathrm{Kspring}\text{:}=\frac{{\mathrm{Fspring}}_{\max }-{\mathrm{Fspring}}_{\min }}{{\mathrm{Hacmltr}}_{\max }}=0.076.Math.\frac{\mathrm{lbf}}{\mathrm{in}}$

(121) Hspring.sub.min:=1 in (This is the spring height at max compression)

(122) $H_{{\mathrm{spring}}_{\mathrm{free}}}\text{:}={\mathrm{Hspring}}_{\min }+{\mathrm{Hacmltr}}_{\max }+\frac{{\mathrm{Fspring}}_{\min }}{\mathrm{Kspring}}=41.456.Math.\mathrm{in}$
(This is the free height of the spring and not meaningful for weight-biased designs)
2) Spring-Based Accumulator:

(123) Parameters are same as for no accumulator above aside from the following:

(124) $\mathrm{Accum}\mathrm{Present}=1$$\mathrm{Kacmltr}=350.0\frac{\mathrm{mL}}{\mathrm{cmH}2O}$${\mathrm{Fspring}}_{\max }\text{:}={\mathrm{Fspring}}_{\min }+\frac{\left({\mathrm{Vacmltr}}_{\max }-{\mathrm{Vacmltr}}_{\min }\right)}{\mathrm{Kacmltr}}.Math.\left(\frac{\pi }{4}.Math.{\mathrm{Dacltr}}^2\right)=3.165.Math.\mathrm{lbf}$$\mathrm{Kspring}\text{:}=\frac{{\mathrm{Fspring}}_{\max }-{\mathrm{Fspring}}_{\min }}{{\mathrm{Hacmltr}}_{\max }}=0.087.Math.\frac{\mathrm{lbf}}{\mathrm{in}}$${\mathrm{Hspring}}_{\mathrm{free}}\text{:}={\mathrm{Hspring}}_{\min }+{\mathrm{Hacmltr}}_{\max }+\frac{{\mathrm{Fspring}}_{\min }}{\mathrm{Kspring}}=37.383.Math.\mathrm{in}$
3) Weight-Based Accumulator:

(125) Parameters are same as for no accumulator above aside from the following

(126) $\mathrm{Accum}\mathrm{Present}=1$${\mathrm{Vacmltr}}_{\mathrm{recovery}}=\left(\begin{array}{c}0.900\\ 0.300\\ 0.010\end{array}\right).Math.L$$\mathrm{Kacmltr}=10000.0\frac{\mathrm{mL}}{\mathrm{cmH}2O}$${\mathrm{Fspring}}_{\max }\text{:}={\mathrm{Fspring}}_{\min }+\frac{\left({\mathrm{Vacmltr}}_{\max }-{\mathrm{Vacmltr}}_{\min }\right)}{\mathrm{Kacmltr}}.Math.\left(\frac{\pi }{4}.Math.{\mathrm{Dacltr}}^2\right)=3.165.Math.\mathrm{lbf}$$\mathrm{Kspring}\text{:}=\frac{{\mathrm{Fspring}}_{\max }-{\mathrm{Fspring}}_{\max }}{{\mathrm{Hacmltr}}_{\max }}=3.045x{10}^{-3}\frac{\mathrm{lbf}}{\mathrm{in}}{\mathrm{Hspring}}_{\mathrm{free}}\text{:}={\mathrm{Hspring}}_{\min }+{\mathrm{Hacmltr}}_{\max }+\frac{{\mathrm{Fspring}}_{\min }}{\mathrm{Kspring}}=823.427.Math.\mathrm{in}$
Initial Conditions:

(127) $T_o=\left[\begin{array}{c}4\\ 4\\ 4\end{array}\right]°C.P_o=\left[\begin{array}{c}0.860\\ 1.000\\ 1.080\end{array}\right]\mathrm{atm}$
where P.sub.o is the external environmental pressure.

(128) The accumulator's behavior was used to determine P.sub.o and V.sub.o, e.g., the initial internal pressure volume at the above P.sub.o and T.sub.o given all other parameters. The accumulator is filled to the target volume, which sets the internal pressure.

(129) $P_o\text{:=}\frac{{\mathrm{Vacmltr}}_{\mathrm{recovery}}}{\mathrm{Kacmltr}}.Math.0+\Delta P_{\mathrm{acmltr}}+P_o=\left(\begin{array}{c}903.576\\ 1048.227\\ 1130.886\end{array}\right).Math.\mathrm{cmH}2{\mathrm{Cp}}_o-P_o=\left(\begin{array}{c}15\\ 15\\ 15\end{array}\right).Math.\mathrm{cmH}2O$

(130) The lung volume was determined by the initial and external pressures as:
Vlung.sub.initial=V.sub.lung(p.sub.o, P.sub.o)=3.5L

(131) The Contained Volume V.sub.o is the sum of accumulator and lung volumes. This is the initial volume of air inside the system. This mass of air will remain unchanged, so the ideal gas law governs its subsequent behavior (relationship of pressure to volume). V.sub.o can be defined as follows for the various accumulator types:

(132) No Accumulator:

(133) $V_o\text{:=}\mathrm{AccumPresent}.Math.{\mathrm{Vacmltr}}_{\mathrm{recovery}}+{\mathrm{Vlung}}_{\mathrm{initial}}=\left(\begin{array}{c}3.500\\ 3.500\\ 3.500\end{array}\right)L$
Spring-Based Accumulator:

(134) $V_o\text{:=}\mathrm{AccumPresent}.Math.{\mathrm{Vacmltr}}_{\mathrm{recovery}}+{\mathrm{Vlung}}_{\mathrm{initial}}=\left(\begin{array}{c}4.500\\ 3.850\\ 3.550\end{array}\right)L$
Weight-Based Accumulator:

(135) $V_o\text{:=}\mathrm{AccumPresent}.Math.{\mathrm{Vacmltr}}_{\mathrm{recovery}}+{\mathrm{Vlung}}_{\mathrm{initial}}=\left(\begin{array}{c}4.400\\ 3.800\\ 3.510\end{array}\right)L$

(136) The equation for final volume Vf is based on the ideal gas law for contained volume,

(137) $\frac{p_f.Math.V_f}{T_f}=\frac{p_o.Math.V_o}{T_o}$
solved for Vf:

(138) 0$V_f=\frac{p_o.Math.V_o}{T_o}.Math.\frac{T_f}{p_f}$

(139) The adapted equation was used in the solve function below:
P.sub.guess:=1.2.Math.p.sub.o.sub.2
given:

(140) $\frac{\mathrm{po}.Math.\mathrm{Vo}}{\mathrm{To}}.Math.\frac{\mathrm{Tf}}{p_{\mathrm{guess}}}=\mathrm{AccumPresent}.Math.V_{\mathrm{acmltr}}\left(p_{\mathrm{guess}},\mathrm{Ptravel}\right)+V_{\mathrm{lung}}\left(p_{\mathrm{guess}},\mathrm{Ptravel}\right)$
with the following constraint added:
P.sub.guess>Ptravel
providing a solution of:
ptravel(po, Vo, To, Tf, Ptravel):=Find)p.sub.guess)

(141) The inputs to this function are the initial conditions together with travel pressure and temperature. The output of this function is the internal pressure.

(142) The solution for a defined range of conditions can then be found:
p.sub.travel.sub.i,j=ptravel(p.sub.o.sub.j,V.sub.o.sub.j,T.sub.o.sub.j, T.sub.f,P.sub.travel.sub.i)
Vlung.sub.travel.sub.i,j=V.sub.lung(p.sub.travl.sub.i,j,p.sub.travel.sub.i)
Vacmltr.sub.travel.sub.i,j=AccumPresent V.sub.acm1tr(P.sub.travel.sub.i,j, P.sub.travel.sub.i)
ΔP.sub.lung.sub.i,j=ptravel.sub.i,j=P.sub.travel.sub.i

(143) FIGS. 21 and 22 show lung pressure and volume in no-accumulator systems given various parameters. Lung pressure and volume were plotted in FIG. 21 given the following:

(144) Initial conditions:

(145) $P_o\equiv \left(\begin{array}{c}\mathrm{.86}\\ 1\\ 1.08\end{array}\right)1\mathrm{atm}\begin{array}{c}\mathrm{Atmospheric}\\ \mathrm{Pressure}\mathrm{at}\\ \mathrm{Recovery}\end{array}$$T_o\equiv \left(\begin{array}{c}4\\ 4\\ 4\end{array}\right)°C.\begin{array}{c}\mathrm{Internal}\\ \mathrm{Temperature}\mathrm{at}\\ \mathrm{Recovery}\end{array}$
Lung parameters: Vlung.sub.max=5L limiting bag/box voume
Accumulator design parameters:

(146) $\mathrm{AccumPresent}\equiv 0\left(0=\mathrm{no}\mathrm{accum}\right)$$\mathrm{Kacmltr}\equiv 400.Math.\frac{\mathrm{mL}}{\mathrm{cmH}2O}$$\mathrm{Realistic}\mathrm{spring}\sim 400\mathrm{mL}\text{/}\mathrm{cmH}2O.\mathrm{Weighted}\mathrm{piston}>5000\mathrm{mL}\text{/}\mathrm{cmH}2O\Delta P_{\mathrm{acmltr}}\equiv 15\mathrm{cmH}2O\mathrm{recovery}\mathrm{pressure}{\mathrm{Vacmltr}}_{\max }\equiv 1.5L\mathrm{maximum}\mathrm{volume}$${\mathrm{Vacmltr}}_{\min }\equiv 50\mathrm{mL}\mathrm{minimum}\mathrm{volume}{\mathrm{Vacmltr}}_{\mathrm{recovery}}\equiv \left(\begin{array}{c}1000\mathrm{mL}\\ 350\mathrm{mL}\\ 50\mathrm{mL}\end{array}\right)\begin{array}{c}\mathrm{Accum}.\\ \mathrm{volume}\mathrm{as}\mathrm{set}\\ \mathrm{by}\mathrm{recovery}\\ \mathrm{team}\end{array}$
In-transit temperature: T.sub.f=8° C.
Airplane cabin pressures: Regulatory Minimum=0.75 atm Older Airplanes=0.78 atm Newer Airplanes=0.80-0.83 atm

(147) Given the above values, FIG. 21 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator based on three different atmospheric pressures at recovery (0.86 atm, 1 atm, and 1.08 atm). Lung volume, recovery at 0.86 Patm 1201, lung volume, recovery at 1 Patm 1202, lung volume, recovery at 1.08 Patm 1203, and accumulator volume 1207 (set to zero here to represent a lack of accumulator) are plotted against the left hand scale. Lung pressure, recovery at 0.86 Patm 1204, lung pressure recovery at 1 Patm 1205, and lung pressure, recovery at 1.08 Patm 1206 are plotted against the right hand scale.

(148) FIG. 22 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator with recovery at 1 atm. The values are the same as given for the nominal (1 atm recovery pressure) plot in FIG. 21.

(149) As shown in FIGS. 21 and 22, the lung volume and pressure vary markedly in response to changes in the in-transit ambient pressure from airplane ascent and descent. These changes can cause damage to the lung tissue and negatively impact viability of the organ for transplant.

(150) FIGS. 23 and 24 show lung pressure and volume in spring-based accumulator systems given various parameters. Lung pressure and volume were plotted in FIG. 23 given the following:

(151) Initial Conditions:

(152) $P_o\equiv \left(\begin{array}{c}\mathrm{.86}\\ 1\\ 1.08\end{array}\right)1\mathrm{atm}\begin{array}{c}\mathrm{Atmospheric}\\ \mathrm{Pressure}\mathrm{at}\\ \mathrm{Recovery}\end{array}$$T_o\equiv \left(\begin{array}{c}4\\ 4\\ 4\end{array}\right)°C.\begin{array}{c}\mathrm{Internal}\\ \mathrm{Temperature}\mathrm{at}\\ \mathrm{Recovery}\end{array}$
Lung Parameters: Vlung.sub.max=5 L
Accumulator Design Parameters:

(153) $\mathrm{AccumPresent}\equiv 1\left(0=\mathrm{no}\mathrm{accum}.\right)$$\mathrm{Kacmltr}\equiv 350.Math.\frac{\mathrm{mL}}{\mathrm{cmH}2O}$$\mathrm{Realistic}\mathrm{spring}\sim 400\mathrm{mL}\text{/}\mathrm{cmH}2O.\mathrm{Weighted}\mathrm{piston}>5000\mathrm{mL}\text{/}\mathrm{cmH}2O\Delta P_{\mathrm{acmltr}}\equiv 15\mathrm{cmH}2O\mathrm{recovery}\mathrm{pressure}{\mathrm{Vacmltr}}_{\max }\equiv 1.5L\mathrm{maximum}\mathrm{volume}$${\mathrm{Vacmltr}}_{\min }\equiv 50\mathrm{mL}\mathrm{minimum}\mathrm{volume}{\mathrm{Vacmltr}}_{\mathrm{recovery}}\equiv \left(\begin{array}{c}1000\mathrm{mL}\\ 350\mathrm{mL}\\ 50\mathrm{mL}\end{array}\right)\begin{array}{c}\mathrm{Accum}.\\ \mathrm{volume}\mathrm{as}\mathrm{set}\\ \mathrm{by}\mathrm{recovery}\\ \mathrm{team}\end{array}$
In-transit temperature: T.sub.f=8° C.
Airplane cabin pressures:

(154) Regulatory Minimum=0.75 atm

(155) Older Airplanes=0.78 atm

(156) Newer Airplanes=0.80-0.83 atm

(157) Given the above values, FIG. 23 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a spring-based accumulator based on three different atmospheric pressures at recovery (0.86 atm, 1 atm, and 1.08 atm). Lung volume, recovery at 0.86 atm, 1 atm, and 1.08 atm 1401 and accumulator volume 1407 are plotted against the left hand scale. Lung pressure, recovery at 0.86 atm, 1 atm, and 1.08 atm 1406 are plotted against the right hand scale. Of note compared to FIG. 21, the lung volume, lung pressure, and accumulator volume curves are consistent across the various atmospheric pressure conditions at recovery because the accumulator volume set at the time of recover compensates for these differences. Furthermore, as shown in FIGS. 23-26, the lung volume and lung pressure curves are much flatter than those in FIGS. 21 and 22 (without an accumulator) while the accumulator volume changes to offset pressure differentials caused by changes in cabin pressure.

(158) FIG. 24 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator with recovery at 1 atm. The values are the same as given for the nominal (1 atm recovery pressure) plot in FIG. 23.

(159) FIGS. 25 and 26 show lung pressure and volume in weight-based accumulator systems given various parameters. Lung pressure and volume were plotted in FIG. 25 given the following:

(160) Initial Conditions:

(161) $P_o\equiv \left(\begin{array}{c}\mathrm{.86}\\ 1\\ 1.08\end{array}\right)1\mathrm{atm}\begin{array}{c}\mathrm{Atmospheric}\\ \mathrm{Pressure}\mathrm{at}\\ \mathrm{Recovery}\end{array}$$T_o\equiv \left(\begin{array}{c}4\\ 4\\ 4\end{array}\right)°C.\begin{array}{c}\mathrm{Internal}\\ \mathrm{Temperature}\mathrm{at}\\ \mathrm{Recovery}\end{array}$
Lung Parameters: Vlung.sub.max=5 L limiting bag/box volume
Accumulator Design Parameters: Vlung.sub.max=5 L limiting bag/box volume
Accumulator Design Parameters

(162) $\mathrm{AccumPresent}\equiv 1\left(0=\mathrm{no}\mathrm{accum}.\right)$$\mathrm{Kacmltr}\equiv 10000.Math.\frac{\mathrm{mL}}{\mathrm{cmH}2O}$$\mathrm{Realistic}\mathrm{spring}\sim 400\mathrm{mL}\text{/}\mathrm{cmH}2O.\mathrm{Weighted}\mathrm{piston}>5000\mathrm{mL}\text{/}\mathrm{cmH}2O\Delta P_{\mathrm{acmltr}}\equiv 15\mathrm{cmH}2O\mathrm{recovery}\mathrm{pressure}{\mathrm{Vacmltr}}_{\max }\equiv 1.5L\mathrm{maximum}\mathrm{volume}$${\mathrm{Vacmltr}}_{\min }\equiv 50\mathrm{mL}\mathrm{minimum}\mathrm{volume}{\mathrm{Vacmltr}}_{\mathrm{recovery}}\equiv \left(\begin{array}{c}900\mathrm{mL}\\ 300\mathrm{mL}\\ 10\mathrm{mL}\end{array}\right)\begin{array}{c}\mathrm{Accum}.\\ \mathrm{volume}\mathrm{as}\mathrm{set}\\ \mathrm{by}\mathrm{recovery}\\ \mathrm{team}\end{array}$
In-transit temperature:

(163) T.sub.f=8° C.

(164) Airplane cabin pressures:

(165) Regulatory Minimum=0.75 atm Older Airplanes=0.78 atm Newer Airplanes=0.80-0.83 atm

(166) Given the above values, FIG. 25 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit with a weight-based accumulator based on three different atmospheric pressures at recovery (0.86 atm, 1 atm, and 1.08 atm). Lung volume, recovery at 0.86 atm, 1 atm, and 1.08 atm 1601 and accumulator volume 1607 are plotted against the left hand scale. Lung pressure, recovery at 0.86 atm, 1 atm, and 1.08 atm 1606 are plotted against the right hand scale. As with FIG. 23, the lung volume, lung pressure, and accumulator volume curves are consistent across the various atmospheric pressure conditions at recovery because the accumulator volume, set at the time of recover compensates for these differences. The lung volume and pressure curves are slightly flatter than the spring-based accumulator curves in FIG. 23.

(167) FIG. 26 shows lung pressure and volume across a range of ambient (atmospheric) pressures during transit without an accumulator with recovery at 1 atm. The values are the same as given for the nominal (1 atm recovery pressure) case in the plot in FIG. 25.

INCORPORATION BY REFERENCE

(168) References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.

EQUIVALENTS

(169) Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.