Blood cooling and heating device and method of operation

Abstract

A device for cooling or heating blood of a patient. The device comprises a fluid circuit, one or more heat pumps, a phase change material that is non-aqueous, and a fluid that is caused to flow. The phase change material and the fluid are in thermal communication with the one or more heat pumps.

Description

BLOOD COOLING AND HEATING DEVICE AND METHOD OF OPERATIONCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The present application claims priority to U.S. Provisional Application No. 63 / 665,378 (filed June 28, 2024) and U.S. Provisional Application No. 63 / 770,097 (filed March 11, 2025), both of which are incorporated herein by reference for all purposes.FIELD

[0002] The present teachings generally relate to a blood heating and cooling device.BACKGROUND

[0003] Cardiopulmonary bypass (“CPB”) machines are used in surgical settings for extracorporeal perfusion of body fluids, such as blood. In this regard, heart and lung function can be supplemented while cardiac surgery is being performed, ensuring blood oxygenation and circulation of the same.

[0004] In some circumstances, blood can be cooled and returned to the body to slow the body’s basal metabolic rate, decreasing oxygen demands. For certain procedures, blood can be cooled, potentially in cooperation with other cooling methods (e.g., dermally-applied ice packs or the like), to induce hypothermia. Normal human body temperature is about 36.5 °C to 37.5 °C. Hypothermia is generally realized at temperatures of < 35 °C.

[0005] Hypothermia is leveraged in surgical settings to protect the brain and vital organs from damage during surgical interventions. Hypothermia may refer to mild (about 32 °C to 35 °C), moderate (28 °C to 32 °C), or deep (< 28 °C). Typically, the minimum body temperature is no less than 20 °C. The level of hypothermia needed will ultimately depend on the patient characteristics, the type of procedure, the complexity of the procedure, and the span of time during which cardiac arrest is needed to perform the procedure. For instance, mild hypothermia is typically used for cardiac arrest times of up to 20 minutes, and deep hypothermia is typically used for cardiac arrest times of up to 40 minutes.

[0006] CPB machines adapted for cooling blood and inducing hypothermia are generally known. Some utilize heat pumps with a liquid flow, typically water. It has been observed that water presents a risk of pathogenic contamination and corrosion. Even where the water flow is fully contained within the machine, spilling or spraying can result from maintenance or cleaning of the machine. Some utilize air flow for cooling. However, air flows within an operating room may disturb sterile air flows caused to flow over the patient or within an operating room, require means for filtration of the same, and contributes to noise within the operating room. Some utilize thermoelectric devices for cooling.

[0007] Generally, the greater the temperature delta, the less efficient the operation of a thermoelectric device. That is, limits are realized in the heat transfers on each side and more voltage is required to pump heat from the cold side to the hot side. There is a need to effectively cool blood to clinically necessary temperatures and do so rapidly to meet time constraints of procedures.

[0008] It would be desirable to provide a device that rapidly cools or heats blood to the target procedural temperature.

[0009] It would be desirable to provide a device that is quieter relative to conventional devices, increasing comfort in an operating room.

[0010] It would be desirable to provide a device that mitigates or even prevents pathogenic risks compared to conventional devices.SUMMARY

[0011] The present disclosure relates to device for cooling or heating blood of a patient, which may address at least some of the needs identified above. The device may comprise a fluid circuit comprising tubing that carries the blood from the patient and back to the patient. The device may comprise one or more heat pumps thermally communicating with the blood.

[0012] The device may comprise and one or both of: a phase change material, which is non-aqueous, in thermal communication with and adapted for exchanging heat with the one or more heat pumps; and a fluid, such as air, that is caused to flow and in thermal communication with and adapted for exchanging heat with the one or more heat pumps.

[0013] The one or more heat pumps may include one or more thermoelectric devices having a hot side and a cold side, the hot side or the cold side thermally communicating with the blood.

[0014] The device may comprise one or more chambers for receiving and holding a pre-determined quantity of the phase change material.

[0015] The phase change material may have a melting point of at least about 50 °C and at most about 90 °C, preferably about 50 °C to about 60 °C, or even more preferably about 55 °C to about 58 °C.

[0016] The phase change material may have a latent heat of fusion of about 200 kJ / kg to about 300 kJ / kg, more preferably about 220 kJ / kg to about 280 kJ / kg, or even more preferably about 240 kJ / kg to about 260 kJ / kg.

[0017] The phase change material may be a salt, a paraffin, a wax, or the like.

[0018] The phase change material may be a salt hydrate, such as ClimSel™ C58.

[0019] A liquid phase of the phase change material may be free from forced flow within the one or more chambers.

[0020] The phase change material may include a combination of two or more phase change materials, each having a different latent heat of fusion and / or a different melting point relative to each other.

[0021] The one or more chambers may be removable from the device. The one or more chambers may comprise a thermal interface, on an exterior surface thereof, adapted and configured to align with and engage with the one or more thermoelectric devices.

[0022] The one or more chambers may comprise one or more heat exchangers extending into an inner volume of the one or more chambers and in thermal communication with the thermal interface.

[0023] The one or more chambers may comprise a mechanism for maintaining contact of a solid phase of the phase change material with the one or more heat exchangers. The mechanism may include a spring -loaded press, an actuator-driven press, one or more drainage holes, a fluid pump, or any combination thereof.

[0024] The device may comprise a thermal diode providing unidirectional flow of the heat relative to the phase change material and preventing the phase change material from re-conditioning the one or more thermoelectric devices.

[0025] The device may comprise a heat pipe extending between the one or more heat pumps and the phase change material, or between the one or more heat exchangers, which are engaged with the one or more heat pumps, and the phase change material.

[0026] The device may be adapted to operate in: a) a cooling mode, whereby the phase change material and / or the fluid thermally communicate with the hot side of the one or more thermoelectric devices; and / or b) a heating mode, whereby the phase change material and / or the fluid thermally communicate with the cold side of the one or more thermoelectric devices.

[0027] The device may be adapted to operate in: a) a first stage whereby the blood is heated or cooled from an initial physiological temperature to a target procedural temperature; and b) a second stage whereby the target procedural temperature is maintained in counteraction to a metabolic function of the patient and / or environmental effects upon the patient.

[0028] The phase change material and the fluid may be operative in cooperation during the first and / or second stages; or the phase change material may be operative without the fluid during the first stage and / or the second stage.

[0029] The fluid may be operative without the phase change material during the first and / or the second stage.

[0030] The phase change material may be operative without the fluid during the first stage and the fluid may be operative without the phase change material during the second stage.

[0031] The fluid and the phase change material may be arranged in parallel or in sequence relative to the one or more heat pumps, or one or more heat exchangers, which are engaged with the one or more heat pumps.

[0032] The one or more thermoelectric devices may operate with a temperature delta, between the hot and cold sides, of about 0 °C to about 40 °C.

[0033] The one or more thermoelectric devices may include 3 or more, up to 12 or even more thermoelectric devices.

[0034] A cooling load of the cold side may be about 200 Watts to about 350 Watts, more preferably about 250 Watts to about 300 Watts, or even more preferably about 270 Watts to about 280 Watts. The cooling load may be more than about 350 Watts, such as up to about 30 kilowatts.

[0035] The blood may be cooled or heated at a rate of about 0.1 °C / minute, more preferably about 0.3 °C / minute, more preferably about 0.5 °C / mmute, more preferably about 0.7 °C / minute, or even more preferably about 0.9 °C / minute.

[0036] The device may comprise a first heat exchanger thermally communicating with one of the hot side or the cold side of the one or more thermoelectric devices and with one or both of the phase change material and the fluid. The device may comprise a second heat exchanger thermally communicating with the other of the hot side or the cold side of the one or more thermoelectric devices and with the tubing carrying the blood. The first heat exchanger and / or the second heat exchanger may be removable from the thermoelectric device.

[0037] The second heat exchanger may have a polygonal cross-section, and at least two sides of the polygonal cross-section may be engaged with the one or more thermoelectric devices.

[0038] The second heat exchanger may have a hexagonal cross-section, and each side thereof may be engaged with at least one of the one or more thermoelectric devices.

[0039] The device may further comprise a length of exchange tubing extending through the second heat exchanger, preferably, generally through a center of the second heat exchanger. The length of exchange tubing may include an inlet connection mechanism and an outlet connection mechanism to which the fluid circuit can connect. The length of exchange tubing is fabricated from an electrically conductive material (e.g., a metallic material).

[0040] The device may comprise one or more temperature sensors including one or more of: a temperature sensor on or proximate to the length of exchange tubing, a temperature sensor at or proximate to an inlet of the blood circuit, a temperature sensor at or proximate to an outlet of the blood circuit, a temperature sensor at or proximate to the cold side, a temperature sensor at or proximate to the hot side, a temperature sensor associated with the fluid, and a temperature sensor associated with the phase change material.

[0041] The device may further comprise a pump for circulating the blood, preferably wherein the pump is separable from the device; and wherein the pump effectuates a blood flow of about 1 Liters / minute to about 10 Liters / minute; more preferably about 1 Liters / minute to about 7 Liters / mmute.

[0042] The device may further comprise one or more fluid moving devices for causing the fluid to flow.

[0043] The device may further comprise one or more blood flow rate sensors.

[0044] The device may further comprise a controller in signal communication with and for coordinating operation of the one or more heat pumps, the one or more fluid moving devices, the pump, the thermal diode, or any combination thereof based upon inputs from the one or more temperature sensors and / or the one or more blood flow rate sensors. The temperature of the blood and / or a core body temperature of the patient may be controlled via closed loop feedback.

[0045] The device may be or may be a module of an extracorporeal perfusion device.

[0046] The present disclosure relates to a method for operating the device for cooling or heating blood of a patient described above, which may address at least some of the needs identified above. The method may comprise: pre-charging the phase change material to a temperature at, above, or below the melting point of the phase change material; operating the device in the first stage whereby the blood is heated or cooled from the initial physiological temperature to the target procedural temperature; operating the device in the second stage whereby the target procedural temperature is maintained in counteraction to the metabolic function of the patient and / or environmental effects upon the patient; and wherein the phase change material and / or the fluid is operable during the first stage; and the phase change material and / or the fluid is operable during the second stage.

[0047] The phase change material and the fluid may be operable during the first stage and the phase change material is operable without the fluid during the second stage. During the second stage, flow of the fluid may be caused to cease.

[0048] The phase change material and the fluid may be operable during the first stage and the fluid may be operable during the second stage without the phase change material. During the second stage, the phase change material may be removed from the extracorporeal perfusion device or thermal communication of the one or more thermoelectric devices may be otherwise interrupted. A fluid moving device may operate at a lower speed relative to the first stage.

[0049] The phase change material may be operable during the first stage without the fluid and the fluid may be operable during the second stage without the phase change material. The fluid moving device may operate at a higher speed in the first stage relative to the second stage.

[0050] The fluid may be operable without the phase change material during the first stage and the second stage.

[0051] Each of the one or more thermoelectric devices may be selectively activated or deactivated to maintain the target procedural temperature and / or when the temperature delta between the hot side and the cold side reaches or surpasses a threshold. Power supplied to the one or more thermoelectric devices may be modulated to maintain the target procedural temperature and / or when the temperature delta between the hot side and the cold side reaches / surpasses a threshold.

[0052] The method may comprise cooling the blood to no less than 30 °C, more preferably no less than 25 °C, more preferably no less than 20 °C, more preferably no less than 15 °C, or even more preferably no less than 4 °C.

[0053] The first stage may be operable for about 20 minutes to about 40 minutes.

[0054] The method may comprise operating the extracorporeal perfusion device in a third stage whereby the blood is cooled or heated from the target procedural temperature to a normal physiological temperature. Cooling or heating may be caused by reversing the polarity of the one or more thermoelectric devices relative to the first and second stages. The phase change material and / or the fluid may be operable during said cooling or heating.

[0055] The method may comprise deactivating the thermal diode during said cooling or heating.

[0056] The method may comprise inducing hypothermia or hyperthermia in a patient.

[0057] The method may comprise swapping the one or more cannisters of the phase change material, during the procedure, respectively with one or more charged cannisters of the phase change material.BRIEF DESCRIPTIONS OF THE DRAWINGS

[0058] FIG. 1 is a schematic of a device according to the present teachings.

[0059] FIG. 2 is a schematic of a device according to the present teachings.

[0060] FIG. 3 is a schematic of a device according to the present teachings.

[0061] FIG. 4 is a schematic of a device according to the present teachings.

[0062] FIG. 5 is a schematic of a device according to the present teachings.

[0063] FIG. 6 is a schematic of a device according to the present teachings.

[0064] FIG. 7A is a schematic of a device according to the present teachings.

[0065] FIG. 7B illustrates an exemplary heat exchanger and phase change material.

[0066] FIG. 8A illustrates an exemplary heat exchanger.

[0067] FIG. 8B illustrates an exemplary heat exchanger.

[0068] FIG. 9 is a schematic of a device according to the present teachings.DETAILED DESCRIPTION

[0069] The present teachings meet one or more of the above needs by the improved device for cooling and heating of blood described herein.

[0070] The device may be used in medical settings, for thermally influencing body fluids of a patient, infusion fluids (e.g., cardioplegia solutions), or both. Where the present disclosure refers to cooling and / or heating blood, unless otherwise stated, the present teachings also contemplate cooling and / or heating other body fluids, infusion fluids, or mixtures of both. Typically, the body fluid is blood. The blood may be drawn from the patient, flow through a circuit, and be returned to the patient. The circuit may be thermally influenced by the device described herein.

[0071] The device may induce hypothermia in a patient. The device may recover and / or maintain normothermia in a patient. Although some examples of the present teachings contemplate that the device may cool the patient, it is contemplated that the device may heat the patient following cooling or exclusively heat the patient without first cooling. The device may induce mild, moderate, or deep hypothermia in a patient.

[0072] Typically, the blood may be cooled to no less than 30 °C, more preferably no less than 25 °C, more preferably no less than 20 °C, or even more preferably no less than 15 °C. Although, it is contemplated that, in some circumstances, the blood may be cooled to as low as 4 °C. It is understood that the temperature to which blood is cooled does not necessarily cool the body of a patient to said temperature. That is, the blood may thermally communicate with the surrounding environment while in the circuit, the patient’s metabolism maycounteract the introduction of cooled blood, the surrounding environmental temperatures may heat the patient, and the blood may be maintained at temperature levels for a finite amount of time (e.g., during an initial cooldown period, prior to a temperature maintenance period). The present teachings contemplate that the patient’s metabolism and environmental factors (e.g., environmental air temperature, temperatures of one or more components in thermal communication with the blood and / or tubing, thermal radiation, or the like) may contribute about 50 Watts to about 150 Watts of heat load. Typically, about 100 Watts.

[0073] As referred to herein, cooling or heating the patient may refer to the core body temperature of the patient. The core body temperature of the patient may or may not be the same as the temperature of the blood of the patient.

[0074] As described in greater detail herein, the device and method of operating the same may be advantageous for fine control of thermoelectric devices for thermal regulation and pump operation for circulating blood. The thermoelectric devices may be regulated to operate to a desired cooling or heating load. The thermoelectric devices may be regulated to operate, in cooperation with one or more heat management techniques described herein (e.g., thermal communication with a phase change material and / or a fluid flow), within a desirable range of a temperature delta between the hot and cold sides thereof. The pump may be regulated in correspondence with the viscosity of blood, which may change as a function of temperature.

[0075] The device may be a module, optionally a removable module, of an extracorporeal perfusion device. The device may be separable from one or more components of the extracorporeal perfusion device such as a pump, an oxygenator (e.g., an extracorporeal membrane oxygenation machine), a cardiopulmonary bypassor, a cardioplegia unit, or the like. The foregoing is applicable to all embodiments.

[0076] The device may comprise one or more thermoelectric devices. The one or more thermoelectric devices may be Peltier devices. The one or more thermoelectric devices may comprise a hot side and a cold side. Electrical energy applied to the one or more thermoelectric devices may cause heat to pump from the cold side to the hot side. The cold side may directly or indirectly thermally communicate with body fluids, infusion fluids, or mixtures of both. The hot side may directly or indirectly thermally communicate with a phase change material and / or a fluid that is caused to flow, as described herein.

[0077] It is understood that hot side and cold side are terms that can refer to either physical side of a thermoelectric device, depending on the direction of current flow (polarity). While the present teachings discuss cooling body fluids in some examples, it is also contemplated that the device may heat body fluids, such as to bring a patient’s body heat back to normal physiological temperatures at the end of a surgical procedure or for exclusive heating. Thus, the physical location of the hot side and the cold side may be understood herein within the contexts of what elements they thermally communicate with and whether the device is operating in a cooling mode or a heating mode.

[0078] In a cooling mode, the phase change material and / or the flowing fluid may thermally communicate with the hot side of the one or more thermoelectric devices. In a heating mode, the phase change material and / or the flowing fluid may thermally communicate with the cold side of the one or more thermoelectric devices.

[0079] The one or more thermoelectric devices may include three or more, six or more, nine or more, twelve or more, fifteen or more, eighteen or more, or even twenty one or more thermoelectric devices. Typically, the device may comprise three to twelve thermoelectric devices. The quantity of thermoelectric devices may be selected based on patient characteristics (e.g., adult vs. child), an initial physiological temperature relative to a target procedural temperature, a desired time to meet the target procedural temperature, extracorporeal perfusion device configuration (e.g., phase change material, fluid flow, or a combination thereof), procedural demands, or any combination thereof.

[0080] With respect to procedural demands, the use cases may vary. Generally, procedures involve a first stage in which blood is cooled from an initial physiological temperature to a target procedural temperature. While typical human physiological temperatures are about 36.5°C to 37.5 °C, patients may begin the procedure in a hyperthermic state (e.g., as high as about 42 °C), thus increasing the delta between the initial physiological temperature and the target procedural temperature. The target procedural temperature may vary (e.g., mild vs. deep hypothermia). In some circumstances, rapid (“crash"’) cooling or rapid heating in a first stage may be required and in other circumstances, slow cooling or heating in a first stage may be required.

[0081] The device of the present teachings may cool or heat blood at a rate of about 0. 1 °C / minute, more preferably about 0.3 °C / minute, more preferably about 0.5 °C / minute, more preferably about 0.7 °C / minute, or even more preferably about 0.9 °C / minute.

[0082] Generally, a temperature delta between the hot and cold sides may be maintained below a threshold in order to ensure efficient operation of the thermoelectric device. Cooperation of a plurality of thermoelectric devices may be undertaken so that a desired rate of cooling / heating of blood is achieved while the temperature delta remains below the threshold. For example, twelve or more thermoelectric devices may be used for crash cooling from the initial physiological temperature relative to the target procedural temperature; and six or less thermoelectric devices may be used for maintaining the target procedural temperature. The one or more thermoelectric devices may operate with a temperature delta, between the hot and cold sides, of about 80 °C or less, more preferably about 60 °C or less, more preferably about 40 °C or less, or even more preferably about 20 °C or less. Preferably, no greater than about 60 °C.

[0083] When operating in a cooling mode, the cooling load of the cold side of the one or more thermoelectric devices may be about 200 Watts to about 350 Watts, more preferably about 250 Watts to about 300 Watts, or even more preferably about 270 Watts to about 280 Watts. Although, the present teachings contemplate operating the one or more thermoelectric devices at a lower cooling load (e.g., about 50 Watts to about 150 Watts during a maintenance stage to counteract metabolic heating of the patient and environmental factors).

[0084] The foregoing may be for typical conditions. However, the present teachings contemplate a cooling load of the cold side of up to about 30 kilowatts. This cooling load may be realized in situations requiring crash cooling (i.e., cooling at a rapid rate) the patient’s body fluids from a hyperthermic state (e.g., about 42 °C) to the minimum of about 4 °C. In such a scenario, it is contemplated that blood flow rates may be up to about 7 to 10 Liters / minute.

[0085] When operating in a cooling mode, the heating load of the hot side of the thermoelectric device may be about 400 Watts or more, about 600 Watts or more, about 1000 Watts or more, or even about 1400 Watts or more. As described herein, the device may comprise a phase change material, a fluid flow, or a combination thereof to draw heat away from the hot side in a cooling mode.

[0086] Exemplary and non-limiting thermoelectric devices may include the models GTT001, GTT003, GTT005, and GTT006, commercially available from Kyocera. Exemplary and non-limiting product configurations may include 40mm x 75 mm overall device size, O1.4xT1.0, element size, 255 pairs of P / N pellets, or any combination thereof.

[0087] The device may comprise one or more heat exchangers. The one or more heat exchangers may function to transmit heat between two or more thermal mediums. The one or more heat exchangers may include a first heat exchanger thermally communicating with the hot side and a second heat exchanger thermally communicating with the cold side. Exemplary heat exchangers may be fabricated from a thermally conductive material such as aluminum, copper, nickel, gold, silver, alloys thereof, or any combination thereof. Exemplary heat exchangers may include corrugations, fins, or the like. The corrugations, fins, or otherwise may function to provide a greater surface area through which heat exchange may occur.

[0088] The one or more heat exchangers may cooperate with tubing through which body fluids, infusion fluids, or mixtures of both may flow. The one or more heat exchangers may at least partially surround the tubing. The one or more heat exchangers may contact about 50% or more, more preferably about 70% or more, more preferably about 90% or more, or even more preferably about 100% of the largest cross-sectional dimension (e.g., the circumference) of the tubing. The one or more heat exchangers may thermally communicate with a length of tubing, which may be referred to herein as a length of exchange tubing to differentiate from any other tubing in the circuit.

[0089] The tubing and / or exchange tubing may be fabricated from a polymer. Exemplary materials from which the tubing is fabricated may include polyvinyl chloride, polyethylene, or polypropylene.

[0090] The exchange tubing may be fabricated from an electrically conductive material (e.g., a metallic material). Exemplary materials may include aluminum, copper, nickel, gold, silver, alloys thereof, or any combination thereof. The exchange tubing may or may not be fabricated from the same material as the heat exchanger it extends through. An interior surface of the exchange tubing may be coated and / or surface-treated. Such coating and / or surface treatment may function to inhibit any harmful interaction of blood or other fluidsdescribed herein and metal. The coating and / or surface treatment may include a diamond-like carbon coating, a heparin-based coating, a nitric oxide-releasing coating, a hydrophilic (e.g., hydrophilic polymer) coating, a metal oxide coating (e.g., silicon oxide or titanium oxide), nano-texturing, electropolishing, or any combination thereof.

[0091] The exchange tubing may be arranged in a serpentine, winding, meandering, coiled, or three- dimensional arrangement, or any combination thereof. The exchange tubing may be arranged within one plane or multiple planes. The exchange tubing may include a plurality of discrete lengths of tubing connected by an inlet manifold and an outlet manifold. The plurality of discrete lengths of tubing may be arranged generally in parallel.

[0092] The tubing may be integrated into or separable from the one or more heat exchangers. It is understood by the present teachings that between procedures performed upon different patients, any tubing carrying body fluids may be discarded. Heat exchangers having integrated tubing may be disposable along with the exchange tubing. Tubing that is separable from a heat exchanger may be disposable while the heat exchanger may be reused for multiple procedures. Tubing integrated into the heat exchanger may comprise a connection mechanism to connect the same to the circuit. The connection mechanism may include a press-fit nipple, a threaded connection, a quick-connect fitting (e.g., a twist-lock fitting), a latched fitting, or the like.

[0093] The one or more heat exchangers may comprise one or more channels in which the tubing may be located. The one or more channels may be adapted and configured to receive the tubing and maintain a positive engagement with at least a portion of the tubing. The one or more channels may have at least one dimension that is generally commensurate with a corresponding dimension of the tubing, such that the tubing may be interference fit within the channel, and also to substantially preclude any discontinuity of conductive heat transfer, by, e.g., any air gaps between the tubing and the heat exchanger. For example, a diameter of the channel may be generally commensurate with a diameter of the tubing. The one or more channels may comprise a plurality of protrusions extending from one or both walls of the one or more channels. The plurality of protrusions may define a space between each protrusion and an opposing wall of the one or more channels. The space may have a dimension generally commensurate with a corresponding dimension of the tubing.

[0094] The one or more heat exchangers may comprise two or more facets, three or more facets, four or more facets, five or more facets, or even six or more facets. Stated differently, the one or more heat exchangers may be in a polygonal form, viewed along a cross-section thereof. Each facet may engage with one or more thermoelectric devices. One or more thermoelectric devices may be arranged along a length of each facet.

[0095] In another aspect, any curved arrangement of tubing (e.g., a serpentine arrangement) may cause one or more regions of positive engagement of the tubing with the one or more channels. In this regard, elastic deformation of the tubing into any curved arrangement may create a tendency for elastic reformation and accordingly the one or more regions of positive engagement.

[0096] In another aspect, the heat exchanger may comprise two or more segments that engage together with the tubing disposed therebetween. Each segment may define a portion of the one or more channels, or the one or more channels may be defined in one segment.

[0097] The one or more heat exchangers and / or the tubing may be removable from the device. In this regard, these components may be reprocessed (i.e., cleaned, disinfected, or sterilized) or replaced in between or during procedures. Preferably, at least the heat exchanger thermally communicating with the blood may be removable for reprocessing, or disposal and replacement.

[0098] The device may comprise one or more pumps. The pumps may function to circulate the blood. The pump may circulate blood, through tubing from a patient, to the device, and back to the patient. Exemplary pumps may include peristaltic pumps, centrifugal pumps, or both. The one or more pumps may effectuate a blood flow of about 1 Liter / minute to about 10 Liters / minute, more preferably about 1 Liter / minute to about 7 Liters / minute. The one or more pumps may be separable from the device.

[0099] As discussed hereinbefore, the thermoelectric devices may cooperate with a phase change material and / or flowing fluid. These elements may thermally communicate with the thermoelectric devices in order to maintain a temperature delta between the hot and cold sides thereof within ranges described herein. Compared to some conventional devices, the device of the present teachings may meet greater demands for target procedural temperatures, heating or cooling rates, or both.

[0100] The device may comprise one or more phase change materials. The phase change material may function to draw heat from the one or more thermoelectric devices in a cooling mode and provide heat to the one or more thermoelectric devices in a heating mode. The phase change material may be non-aqueous. Non-aqueous means of heat transfer and / or storage may be advantageous for avoiding pathogenic risks in clinical settings, compared to aqueous mediums. The phase change material may be biocidal.

[0101] The phase change material may be in direct or indirect thermal communication with the one or more thermoelectric devices. The phase change material may thermally communicate with the hot side in a cooling mode, or the cold side in a heating mode.

[0102] The phase change material may be in thermal communication with one or more heat exchangers, which are in thermal communication with the one or more thermoelectric devices. The phase change material may be preferably in thermal communication with corrugations or fins of the one or more heat exchangers.

[0103] It is contemplated by the present teachings that as the phase change material transforms from a solid phase into a liquid phase, the liquid phase may displace the solid phase from contact with the one or more heat exchangers. By way of example, at least a portion of the solid phase may separate from a heat exchanger and float upon the liquid phase. In this regard, the device may comprise a mechanism for maintaining contact of the solid phase with the one or more heat exchangers. The mechanism may be a passive mechanism or an active mechanism. The passive mechanism may include a spring-loaded press, a drain hole, or both. The spring-loadedpress may press the solid phase upon one or more heat exchangers. The drain hole may allow drainage of the liquid phase to avoid the liquid phase from displacing the solid phase. The active mechanism may include an actuator-driven press, a fluid pump, or both. The actuator-driven press may press the solid phase upon one or more heat exchangers. The fluid pump drain the liquid phase to avoid the liquid phase from displacing the solid phase. Any combination of the foregoing mechanisms may be employed.

[0104] The device may comprise one or more heat pipes. The one or more heat pipes may function to carry heat between the one or more thermoelectric devices and the phase change material. The heat pipe may be understood to include a phase change material (e.g., water), but it is understood that this phase change material may be different from the main phase change material described herein. The phase change material of the heat pipe may be sealed within the pipe (e.g., typically a copper pipe). The phase change material of the heat pipe may be sealed within the pipe with a pressure that is less than atmospheric pressure. In this regard, the boiling point of the phase change material within the pipe may be lower relative to atmospheric pressure. The phase change material of the heat pipe may vaporize, travel generally in a first direction through the heat pipe, condense, and then travel generally in a second direction through the heat pipe. In another aspect, the heat pipe may be a carbon graphite pipe, having thermal conductivity along one axis.

[0105] The device may comprise one or more thermal diodes. The one or more thermal diodes may function to constrain heat to a unidirectional flow. In this regard, during a cooling mode, the phase change material may be prevented from re-heating the one or more thermoelectric devices. In this regard, it is understood that, at least at times, the temperature of the hot side of the one or more thermoelectric devices may fall below the temperature of the phase change material. The thermal diode may be de-activated in a heating mode to allow heating of the patient’s blood. The thermal diode may be associated structurally with the heat pipe.

[0106] The phase change material may have a melting point of at least about 50 °C and at most about 90 °C, preferably about 50 °C to about 60 °C, or even more preferably about 55 °C to about 58 °C. Thermoelectric devices may be generally susceptible to damage at about 90 °C or more. With a melting point at or near room temperature (e.g., about 20 °C to about 25 °C), the phase change material may absorb heat from the environment.

[0107] The phase change material may have a latent heat of fusion of about 200 kJ / kg to about 300 kJ / kg, more preferably about 220 kJ / kg to about 280 kJ / kg, or even more preferably about 240 kJ / kg to about 260 kJ / kg.

[0108] The phase change material may be a salt, a paraffin, a wax, or the like. The phase change material may be a salt hydrate. An exemplary phase change material may include ClimSel™ C58, commercially available from Climator Sweden AB.

[0109] The one or more phase change materials may include a combination of two or more phase change materials. Each of the two or more phase change materials may have a different latent heat of fusion and / or adifferent melting point relative to each other. The different phase change materials may be located in separate chambers or the same chamber.

[0110] The device may comprise one or more chambers. The one or more chambers may function to receive / hold a pre-determined quantity of the phase change material. The pre -determined quantity may be based on an age of the patient, a gender of the patient, a weight of the patient, a body mass index of the patient, a duration of a medical procedure (e.g., an operation) to be performed upon the patient, an initial physiological temperature of the patient, a target procedural temperature, or any combination thereof. The pre-determined quantity of the phase change material may fill less than a total volume of the one or more chambers, to allow for thermal expansion.[01H] The one or more chambers may be formed around at least a portion of one or more heat exchangers. At least a portion of the corrugations, fins, or otherwise of the one or more heat exchangers may extend into the one or more chambers. The mechanism for maintaining contact of the solid phase with the one or more heat exchangers, as described above, may be structurally integrated into the one or more chambers.

[0112] The liquid phase of the phase change material may be free from forced flow (e.g., forced flow within the chamber).

[0113] The one or more chambers may be removable from the device. The device may comprise one or more receptacles for receiving the one or more chambers. In this regard, the one or more chambers may engage a charging device to charge the phase change material. Charge may refer to decreasing a temperature of the phase change material to or below its melting point (e.g., for a cooling mode of the device described herein) or increasing the temperature of the phase change material above its melting point (e.g., for a heating mode of the device described herein).

[0114] The one or more chambers may not be removable from the device. In this regard, charging the phase change material may be undertaken via the one or more thermoelectric devices on-board the device. Although, the present teachings also contemplate that phase change material in removable chambers may also be charged via the one or more thermoelectric devices on-board the device.

[0115] The one or more chambers may comprise one or more thermal interfaces engageable directly or indirectly with the one or more thermoelectric devices and a charging device. These thermal interfaces may or may not be the one or more heat exchangers that engage with the one or more thermoelectric devices during operation of the device described herein.

[0116] The device may comprise a fluid that is caused to flow. The fluid flow may function to draw heat from the one or more thermoelectric devices in a cooling mode and provide heat to the one or more thermoelectric devices in a heating mode. The fluid may be in direct or indirect thermal communication with the thermoelectric device.

[0117] The fluid may be air drawn into the device and expelled from the device. In this regard, the air may be at the temperature of the surrounding atmosphere (e.g., room temperature). The fluid may be caused to flow by one or more fluid moving devices. Exemplary' fluid moving devices may include blowers, such as axial blowers or radial blowers. The fluid may flow through a conduit. The fluid may be caused to flow over and / or through a heat exchanger located within the conduit. The conduit may comprise a filter (e.g., a HEPA filter) for maintaining a sterile environment in the operating room.

[0118] The temperature delta between the inlet air and the outlet air may be about 10 °C to about 20 °C, more preferably about 12 °C to about 15 °C.

[0119] It is understood that the phase change material and fluid flow may be operative alone or in combination. Such independent or cooperative operation may be active at different times during a procedure. There may be advantages for each solution in different stages of operation of the device.

[0120] It is understood that operating rooms typically have procedurally significant airflows. In some circumstances, an air curtain may be caused to flow over the patient in order to influence a sterile environment. In some circumstances, an air flow from the ceiling toward the floor may be caused to maintain any pathogens below the patient. In these regards, the fluid flow of the device may be advantageously operated to avoid disturbing the procedurally significant airflows. By way of example but not limitation, the fluid flow of the device may be operative to maintain the target procedural temperature. By way of another example, the fluid flow may cooperate with the phase change material to heat or cool blood from an initial physiological temperature to a target procedural temperature. In either case, cooling or heating demands upon the fluid flow may not be so high as to necessitate the fluid moving device (e.g., a blower) to operate at a speed that would disturb the above-described procedurally significant airflows.

[0121] The fluid flow and the phase change material may be arranged in parallel or in sequence. In parallel may refer to both the fluid flow and the phase change material thermally communicating with a portion of the one or more thermoelectric devices. In sequence may refer to the fluid flow or the phase change material thermally communicating with the one or more thermoelectric devices and the other of the fluid flow or the phase change material having thermal influence downstream or upstream of the former element. For example, a fluid flow may thermally communicate with one or more thermoelectric devices and a phase change material may be thermally influenced by the fluid flow.

[0122] The device may be adapted to operate in a first stage whereby the blood is cooled from an initial physiological temperature to a target procedural temperature. The device may be adapted to operate in a second stage whereby the target procedural temperature is maintained in counteraction to a metabolic function of the patient, environmental factors, or both.

[0123] The phase change material and the fluid may be operative in cooperation during the first and / or second stages.

[0124] The phase change material may be operative without the fluid during the first or second stages.

[0125] The fluid may be operative without the phase change material during the first or second stages.

[0126] The phase change material may be operative without the fluid during the first stage and the fluid may be operative without the phase change material during the second stage.

[0127] The phase change material may be operative with the fluid during the first stage and the fluid may be operative without the phase change material during the second stage.

[0128] Without intending to be limiting, it may be advantageous for the fluid and the phase change material to be operative during the first stage. In this regard, more heat may be generated by the one or more thermoelectric devices during this stage relative to the second stage. Thus, the fluid and the phase change material may cooperate in operation to remove heat from the hot side of the thermoelectric device and provide for crash cooling. After the target procedural temperature is realized, the fluid flow may be sufficient to maintain the same, in counteraction to the patient’s metabolism, environmental factors, or both.

[0129] It is also contemplated that in some circumstances the fluid flow may be operative without the phase change material during the first and second stages. The fluid flow, where operable in both stages, may be caused to flow at a higher rate in the first stage relative to the second stage, although the flow rate may be less than a threshold that may disturb the procedurally significant airflows of the operating room.

[0130] The phase change material may have a peak heat absorption range. During operation at this range, the phase change material may operate without the fluid.

[0131] The fluid flow may be advantageous for operation in the second stage, due to the limited working life of the phase change material. Although the present teachings contemplate that phase change material chambers may be swapped out during a procedure to re-charge, the fluid flow may operate continuously without user input. This may be advantageous for circumstances in which an emergency or complication may extend the overall procedure duration.

[0132] The device may comprise one or more temperature sensors. Exemplary temperature sensors may include thermistors, thermocouples, or the like.

[0133] The one or more temperature sensors may include: a temperature sensor on or proximate to exchange tubing, a temperature sensor at or proximate to an inlet of the blood circuit, a temperature sensor at or proximate to an outlet of the blood circuit, a temperature sensor at or proximate to the cold side (such as on a heat exchanger of the cold side), a temperature sensor at or proximate to the hot side (such as on a heat exchanger of the hot side), a temperature sensor associated with the fluid (e.g., on or within a conduit through which the fluid flows), a temperature sensor associated with the phase change material (e.g., on or within the one or more chambers), or any combination thereof.

[0134] Preferably, the device may comprise one or more temperature sensors on or proximate to exchange tubing. The one or more temperature sensors may be located proximate to an outlet of the exchange tubing.

[0135] The device may comprise one or more blood flow rate sensors. The one or more blood flow rate sensors may be advantageous where the device including the tubing may be separable from a pump, and thus may not signally communicate with the pump. Moreover, the one or more blood flow rate sensors may provide redundancy in confirming the flow rate.

[0136] The device may leverage feedback from one or more of these sensors to control the fluid moving devices, the thermoelectric devices, the pump, the thermal diode, or any combination thereof.

[0137] The temperature of the blood and / or the core body temperature of the patient may be controlled via a closed loop feedback of one or more of the foregoing sensors.

[0138] The device may comprise one or more controllers. The one or more controllers may be in signal communication with the one or more temperature sensors, the one or more blood flow rate sensors, the one or more thermoelectric devices, the one or more fluid moving devices, the pump, the thermal diode, or any combination thereof. The one or more controllers may coordinate operation of the one or more thermoelectric devices, the one or more fluid moving devices, the pump, the thermal diode, or any combination thereof, based upon inputs from the one or more temperature sensors, the one or more blood flow rate sensors, or both.

[0139] The present teachings may meet one or more of the above needs by the improved method of operating the device described herein.

[0140] The method may comprise one or more of the following steps. Some of the steps may be duplicated, removed or eliminated, rearranged relative to other steps, combined into one or more steps, separated into two or more steps, or a combination thereof.

[0141] The method may comprise pre-charging the phase change material to a temperature at or below the melting point of the phase change material, for a cooling mode. The method may comprise pre-charging the phase change material to a temperature above the melting point of the phase change material, for a heating mode.

[0142] A pre-determined quantity of phase change material may be introduced into one or more chambers, or one or more chambers may be pre-loaded with phase change material.

[0143] The method may comprise operating the device in the first stage whereby the blood is cooled from the initial physiological temperature to the target procedural temperature.

[0144] The method may comprise operating the device in the second stage whereby the target procedural temperature is maintained in counteraction to the metabolic function of the patient.

[0145] The phase change material and / or the fluid may be operable during the first stage. The phase change material and / or the fluid may be operable during the second stage.

[0146] The phase change material and the fluid may be operable during the first stage and the phase change material may be operable during the second stage without the fluid. During the second stage, flow of the fluid may be caused to cease by de-activation of the fluid moving device.

[0147] The phase change material and the fluid may be operable during the first stage and the fluid may be operable during the second stage without the phase change material. During the second stage, the phase change material may be removed from the extracorporeal perfusion device or thermal communication of the one or more thermoelectric devices is otherwise interrupted. Such interruption may also result from the phase change material reaching a capacity of heat absorption relative to the temperature of the hot side of the one or more thermoelectric devices. During the second stage, the fluid moving device may operate at a lower speed relative to the first stage.

[0148] The phase change material may be operable without the fluid during the first stage and the fluid may be operable without the phase change material during the second stage. The fluid moving device may operate at a higher speed in the first stage relative to the second stage.

[0149] The fluid is operable without the phase change material during the first stage and the second stage.

[0150] The method may comprise swapping the one or more cannisters of the phase change material, during the procedure, respectively with one or more charged cannisters of the phase change material.

[0151] The method may comprise selectively activating and / or deactivating the one or more thermoelectric devices to maintain the target procedural temperature. The method may comprise selectively activating and / or deactivating the one or more thermoelectric devices when the temperature delta between the hot side and the cold side reaches or surpasses a threshold.

[0152] The method may comprise modulating the power supplied to the one or more thermoelectric devices to maintain the target procedural temperature. The method may comprise modulating the power supplied to the one or more thermoelectric devices when the temperature delta between the hot side and the cold side reaches or surpasses a threshold. The one or more thermoelectric devices may be powered by pulse width modulation, constant current control, or the like.

[0153] The first stage may be operable for about 20 minutes to about 40 minutes.

[0154] The method may comprise operating the device in a third stage whereby the blood is heated from the target procedural temperature to a normal physiological temperature. The heating may be caused by reversing the polarity of the one or more thermoelectric devices. The phase change material and / or the fluid may by operable during said heating to supply heat to the one or more thermoelectric devices. The thermal diode may be deactivated during heating.

[0155] It is contemplated that while typically the first, second, and third stages described above may proceed sequentially, it is possible that switching between any of these stages may be performed, such as in the case of a complication. For instance, while heating the patient in the third stage, aortic rapture may require first stage crash cooling of the patient.

[0156] The device may operate to induce hypothermia in a patient.

[0157] FIG. 1 through FIG. 5 and FIG. 7A are schematics of a blood heating and cooling device 10. The device 10 comprises a fluid circuit 12 that receives blood from a patient 14 via an mlet port 14 and returns blood to the patient 14 via an outlet port 18. Flow through the fluid circuit 12 is influenced by a pump 20. As shown, the fluid circuit 12 is closed, but it is contemplated that the fluid circuit may include one or more other functional modules, such as an extracorporeal membrane oxygenation machine, a cardiopulmonary bypassor, or a cardioplegia unit. Moreover, it is contemplated that the fluid circuit 12 may include one or more valves, filters, air traps, reservoirs, or otherwise.

[0158] FIG. 1 through FIG. 5 and FIG. 7A show configurations in which the fluid circuit 12 includes exchange tubing 22 adapted and configured for thermal exchange with, e.g., one or more heat exchangers, one or more heat pumps, or otherwise, as described in more detail below and elsewhere herein. In this regard, the exchange tubing 22 may be arranged in a serpentine, winding, meandering, coiled, or like arrangement, which provides for greater surface area for thermal exchange. It is also contemplated that the exchange tubing 22 may be arranged as a plurality of tubes, such as arranged in parallel, fed fluid by an inlet manifold and dispensing fluid, by an outlet manifold, back into a single tube of the fluid circuit 12. It is also contemplated that the exchange tubing 22 may be arranged along a plane, or in three dimensions. As a non-limiting example of a three-dimensional arrangement, one length of tubing may extend through a first plane, another length of tubing may extend through a second plane, and an intermediate length of tubing may extend between the first and second planes. In some aspects, it is contemplated that the exchange tubing 22 may be arranged in a generally straight line. Although straight lines of exchange tubing 22 is illustrated, it is understood that one or any combination of exchange tubing 22 arrangements described herein, such as in this paragraph, may be employed. In other words, the illustrated straight lines of exchange tubing 22 are not intended to be limiting.

[0159] The device 10 functions to cool blood of the patient 14 below typical physiological temperatures, and even induce hypothermia in the patient 14. Several heat transfers are realized with the device 10. Blood enters the fluid circuit 12 via the inlet port 16, flows through the exchange tubing 22 to shed heat via elements such as heat exchangers described in greater detail below, and then flows to the outlet port 16 to be returned to the patient 14.

[0160] Before the blood leaves the patient 14 and after the blood is returned to the patient 14, the patient’s metabolism and environmental heating of the patient 14 effectuates a heat transfer 62 to the blood. Without intending to be bound by theory, it is estimated that metabolic heat transfer may be, for an average adult, about 80 Watts to about 120 Watts. Throughout the entire length or substantially the entire length of the fluid circuit 12, the ambient environment may thermally communicate therewith and effectuate a heat transfer 26 with the fluid circuit 12. Additionally, there are one or more heat transfers 28 respectively between the exchange tubing 22 and one or more elements described in the following paragraphs.

[0161] FIG. 1 through FIG. 3 show the exchange tubing 22 in thermal communication with a first heat exchanger 30 and a second heat exchanger 32. The device 10 comprises a heat pump 34 in thermal communication with the first heat exchanger 30. The second heat exchanger 32 thermally communicates with the ambient environment. Optionally, a blower may effectuate an air flow across a surface area of the second heat exchanger 32. The cooling power attributed to the heat pump 34 is typically greater than that of the ambient environment. The heat pump 34 may be configured as a thermoelectric device 36. The thermoelectric device 36 has a cold side 38 and a hot side 40. In this regard, electric energy provided to an array of semiconductors disposed between the cold and hot sides 38, 40 causes heat flow from the cold side 38 to the hot side 40. A third heat exchanger 42 is in thermal communication with the hot side 40.

[0162] With respect to the terms, “hot side” and “cold side” it is understood that the polarity of the thermoelectric device 36 may be reversed to cause the hot and cold sides to swap position. It is within the scope of the present teachings that in some aspects blood may be heated, in which case the illustrated hot and cold sides would swap position. The illustrations are merely exemplary, and are verbally described from the perspective of one possible operation, which is a cooling operation.

[0163] In FIG. 1, the third heat exchanger 42 thermally communicates with a fluid 44, which is caused to flow by a fluid moving device 46 (e.g., a blower). The fluid 44 receives heat and is expelled from the device 10, and mixes with the ambient environment. As shown, the fluid is air, which is received into the fluid moving device 46 from the ambient environment surrounding the device 10. Typically required in medical settings, particularly operating rooms, are filters 48 for filtering forced air and maintaining the setting as sterile.

[0164] In FIG. 2, the third heat exchanger 42 thermally communicates with a phase change material 50. The phase change material 50 is pre-charged to a temperature below the melting point of the phase change material 50. Thermal energy absorbed by the phase change material 50 may cause a phase change thereof, such as melting from a solid to a liquid.

[0165] In FIG. 3, the third heat exchanger 42 thermally communicates with a fluid 52 and a phase change material 54, arranged in parallel. The fluid 52 is caused to flow by a fluid moving device 56 and a filter 58 maintains or at least substantially maintains the fluid 52 (e.g., air) exiting the device 10 as sterile. The third heat exchanger 42 also thermally communicates with a heat pipe 60 that then thermally communicates with the phase change material 54. The heat pipe 60 includes a thermal diode 62, which ensures unidirectional heat flow to the phase change material 54.

[0166] As discussed above, the fluid flow and the phase change material can function alone or in cooperation. It is also contemplated that the fluid and the phase change material can function in series, whereas FIG. 3 shows an in-parallel arrangement. For example, the third heat exchanger 42 may thermally communicate with the fluid 52 and the fluid 52 may thermally communicate with the phase change material 54; or the third heat exchanger42 may thermally communicate with the phase change material 54 and the phase change material 54 may thermally communicate with a fluid 52 caused to flow by a fluid moving device 56.

[0167] FIG. 4 through FIG. 6 illustrate one or more heat pumps 64a-64f (e.g., thermoelectric devices) in thermal communication with one or more first heat exchangers 70a-70b, each heat pump 64a-64f having a cold side 66a-66f and a hot side 68a-68f.

[0168] In FIG. 4, one heat pump 64a is shown in thermal communication with a first heat exchanger 70 on the cold side thereof 66a. The hot side 68a of the heat pump 64a is in thermal communication with a second heat exchanger 72a. The second heat exchanger 72a can shed heat to the ambient environment, or it is contemplated that it may shed heat to a phase change material, such as shown in FIG. 7A.

[0169] In FIG. 5, two heat pumps 64a, 64b are shown on opposing sides of and in thermal communication with the exchange tubing 22. The heat pumps 64a, 64b are in respective thermal communication with a first heat exchanger 70 on the cold sides thereof 66a, 66b. The hot sides 68a, 68b of the heat pumps 64a, 64b are in thermal communication with second heat exchangers 72a, 72b. Either or both of the second heat exchangers 72a, 72b can shed heat to the ambient environment, or it is contemplated that either or both may shed heat to a phase change material, such as shown in FIG. 7A.

[0170] FIG. 6 shows a cross-section of the device 10, which includes six heat pumps 64a-64f arranged around a first heat exchanger 70, and six second heat exchangers 72a-72f respectively in thermal communication with the heat pumps 64a-64f. The first heat exchanger 70 is in a generally hexagonal form, although, the present teachings contemplate any suitable polygonal form (e.g., square, pentagonal, octagonal, etc.). The exchange tubing 22 extends through the first heat exchanger 70.

[0171] The second heat exchangers 72a-72f can shed heat via any suitable method described herein, such as shedding heat to the ambient environment, to a flowing fluid (see, e.g., FIG. 1), a phase change material (see, e.g., FIG. 2, FIG. 7A), or otherwise.

[0172] FIG. 7A is a schematic of a blood heating and cooling device 10, having similar configuration as in FIG. 4 through FIG. 6. Each of the second heat exchangers 72a, 72b thermally communicate with a phase change material 74a, 74b, which absorbs heat from the second heat exchangers 72a, 72b and undergoes a phase change.

[0173] FIG. 7B illustrates an exemplary heat exchanger 76 and phase change material 78. One exemplary phase change material 78 may be in the form of a wax. The heat exchanger 76 includes a plurality of fins 80 configured and adapted to maximize a surface area through which heat can be exchanged. In this regard, the waxy phase change material 78 can be influenced into contact with the heat exchanger 76, particularly the plurality of fins 80. The phase change material 78 can be contained within a chamber 82, which also encapsulates the heat exchanger 76.

[0174] The present teachings contemplate that the phase change material 78 may be present in the chamber 82 in a solid phase 79 A and a liquid phase 79B. Preferably, most if not all of the solid phase 79 A may be in contact with the heat exchanger 76. As the solid phase 79 A transitions to the liquid phase 79B, the liquid phase 79B may pool in the bottom of the chamber 82. In some cases, the liquid phase 79B may displace the solid phase 79A from contact with the heat exchanger 76. In some cases, a contact area of the solid phase 79A with the heat exchanger 76 may decrease as it transitions to the liquid phase 79B. The present teachings contemplate a suitable passive and / or active mechanism for maintaining contact of the solid phase 79A with the heat exchanger 76. Some passive methods may include a spring-loaded press 83 functioning to press the solid phase toward the heat exchanger 76.

[0175] The exchange tubing may be integral to or separable from the heat exchanger. Where the exchange tubing is integral to the heat exchanger, the heat exchanger may be disposable, with the exchange tubing, after a procedure as described herein. Where the exchange tubing is separable from the heat exchanger, only the exchange tubing and other tubing in the fluid circuit may be disposable, whereas the heat exchanger can be used for multiple procedures.

[0176] FIG. 8A illustrates an exemplary heat exchanger 84 in which exchange tubing 86 is integrated. In this regard, the exchange tubing 86 has an inlet 88 and an outlet 90 for connecting to the tubing of the fluid circuit. The inlet and outlet 88, 90 can have any suitable connection mechanism, such as a press-fit nipple, locking connector, or the like.

[0177] FIG. 8B illustrates a heat exchanger 92 in which exchange tubing 94 is separable therefrom. The exchange tubing 94 is disposed within a channel 96 within which protrusions 98 are formed to engage the exchange tubing 94. Any suitable engagement of the exchange tubing 94 within the heat exchanger 92 is contemplated, including but not limited to press-fitting, clamping the heat exchanger around the exchange tubing (i.e., via bringing two parts of the heat exchanger together around the exchange tubing), or the like.

[0178] Although FIG. 8A and FIG. 8B illustrate, respectively, a serpentine tubing arrangement and a straight- line tubing arrangement, any configuration of the tubing, as described herein, may be used in either of the integral and separable configurations with respect to the heat exchanger.

[0179] FIG. 9 is a schematic of a blood heating and cooling device 10. The device 10 comprises a controller 100, a heat pump 102, sensors 104, 106 and a pump 108. The controller 100 is in signal communication with each of the foregoing. The device 10 can include one or both of the sensors 104, 106, which are located proximate to the outlet of the exchange tubing 110. The sensors 104, 106 may sense the temperature of the fluid (e.g., blood) circulating through the device 10. In this regard, the controller 100 may regulate the operation of the heat pump 102 and / or pump 108 based on the sensed temperature of the fluid.

[0180] It is understood that the above description is intended to be illustrative and not restrictive. The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application.

[0181] Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Many embodiments as well as many applications besides the examples provided herein will be apparent to those of skill in the art upon reading the above description.

[0182] Accordingly, the specific embodiments of the invention set forth herein are not intended as being exhaustive or limiting of the teachings. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0183] The omission in the following claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter, nor should it be regarded that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

[0184] The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes.

[0185] Plural elements or steps can be provided by a single integrated element or step. Alternatively, a single element or step might be divided into separate plural elements or steps.

[0186] The disclosure of “a” or “one” to describe an element or step is not intended to foreclose additional elements or steps.

[0187] The use of “about” or “approximately” in connection with a range applies to both ends of the range. Thus, “about 20 to 30” is intended to cover “about 20 to about 30”, inclusive of at least the specified endpoints.

[0188] Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints in increments of one unit provided that there is a separation of at least 2 units between any lower endpoint and any higher endpoint. As an example, if it is stated that the amount of a component, a property, or a value of a process variable such as, e.g., temperature, pressure, time, and the like is, e.g., from 1 to 90, from 20 to 80, or from 30 to 70, it is intended that intermediate range values such as, e.g., 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc., are within the teachings of this specification. Likewise, individual intermediate values are also within the present teachings.

[0189] For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01, or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest endpoint and the highest endpoint enumerated are to be considered to be expressly stated in this application in a similar manner.

[0190] The term “consisting essentially of’ to describe a combination shall include the elements, ingredients, components, or steps identified, and such other elements ingredients, components or steps that do not materiallyaffect the basic and novel characteristics of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, ingredients, components, or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components, or steps.

[0191] While the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used to distinguish one element, component, region, layer, and / or section from another region, layer, and / or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, and / or section discussed below could be termed a second element, component, region, layer, and / or section without departing from the teachings.

[0192] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the drawings. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0193] The terms “generally” or “substantially” to describe angular measurements may mean about + / - 10° or less, about + / - 5° or less, or even about + / - 1° or less. The terms “generally” or “substantially” to describe angular measurements may mean about + / - 0.01° or greater, about + / - 0.1° or greater, or even about + / - 0.5° or greater.

[0194] The terms “generally” or “substantially” to describe linear measurements, percentages, or ratios may mean about + / - 10% or less, about + / - 5% or less, or even about + / - 1% or less. The terms “generally” or “substantially” to describe linear measurements, percentages, or ratios may mean about + / - 0.01% or greater, about + / - 0.1% or greater, or even about + / - 0.5% or greater.

[0195] REFERENCE NUMERALS

[0196] 10 Device

[0197] 12 Fluid circuit

[0198] 14 Patient

[0199] 16 Inlet port

[0200] 18 Outlet port

[0201] 20 Pump

[0202] 22 Exchange tubing

[0203] 24 Heat transfer

[0204] 26 Heat transfer

[0205] 28 Heat transfer

[0206] 30 First heat exchanger

[0207] 32 Second heat exchanger

[0208] 34 Heat pump

[0209] 36 Thermoelectric device

[0210] 38 Cold side

[0211] 40 Hot side

[0212] 42 Third heat exchanger

[0213] 44 Fluid

[0214] 46 Fluid moving device

[0215] 48 Filter

[0216] 50 Phase change material

[0217] 52 Fluid

[0218] 54 Phase change material

[0219] 56 Fluid moving device

[0220] 58 Filter

[0221] 60 Heat pipe

[0222] 62 Thermal diode

[0223] 64a-64f Heat pump

[0224] 66a-66f Cold side

[0225] 68a-68f Hot side

[0226] 70 First heat exchanger

[0227] 72a-72f Second heat exchanger

[0228] 74a-74b Phase change material

[0229] 76 Heat exchanger

[0230] 78 Phase change material

[0231] 79A Solid phase

[0232] 79B Liquid phase

[0233] 80 Plurality of fins

[0234] 82 Chamber

[0235] 83 Spring-loaded press

[0236] 84 Heat exchanger

[0237] 86 Exchange tubing

[0238] 88 Inlet

[0239] 90 Outlet

[0240] 92 Heat exchanger

[0241] 94 Exchange tubing

[0242] 96 Channel

[0243] 98 Protrusions

[0244] 100 Controller

[0245] 102 Heat pump

[0246] 104 Sensor

[0247] 106 Sensor

[0248] 108 Pump

[0249] 110 Exchange tubing

Claims

1.CLAIMSWhat is claimed is:Claim 1 : A device for cooling or heating blood of a patient, the device comprising: a fluid circuit comprising tubing that carries the blood from the patient and back to the patient; one or more heat pumps thermally communicating with the blood; and one or both of: optionally, a phase change material, which is non-aqueous, in thermal communication with and adapted for exchanging heat with the one or more heat pumps; and a fluid, such as air, that is caused to flow and in thermal communication with and adapted for exchanging heat with the one or more thermoelectric devices.Claim 2: The device according to Claim 1, wherein the one or more heat pumps include one or more thermoelectric devices having a hot side and a cold side, the hot side or the cold side thermally communicating with the blood.Claim 3 : The device according to Claim 1 or Claim 2, further comprising one or more chambers for receiving and holding a pre-determined quantity of the phase change material.Claim 4: The device according to any one of the preceding claims, wherein the phase change material has a melting point of at least about 50 °C and at most about 90 °C, preferably about 50 °C to about 60 °C, or even more preferably about 55 °C to about 58 °C.Claim 5: The device according to any one of the preceding claims, wherein the phase change material has a latent heat of fusion of about 200 kJ / kg to about 300 kJ / kg, more preferably about 220 kJ / kg to about 280 kJ / kg, or even more preferably about 240 kJ / kg to about 260 kJ / kg.Claim 6: The device according to any one of the preceding claims, wherein the phase change material is a salt, a paraffin, a wax, or the like.Claim 7 : The device according to any one of the preceding claims, wherein the phase change material is a salt hydrate, such as ClimSel™ C58.Claim 8: The device according to any one of the preceding claims, wherein a liquid phase of the phase change material is free from forced flow within the one or more chambers.Claim 9: The device according to any one of the preceding claims, wherein the phase change material includes a combination of two or more phase change materials, each having a different latent heat of fusion and / or a different melting point relative to each other.Claim 10: The device according to any one of Claims 2 through 9, wherein the one or more chambers are removable from the device, and comprise a thermal interface, on an exterior surface thereof, adapted and configured to align with and engage with the one or more thermoelectric devices; and wherein the one or more chambers comprise one or more heat exchangers extending into an inner volume of the one or more chambers and in thermal communication with the thermal interface.Claim 11: The device according to any one of Claims 2 through 10, wherein the one or more chambers comprise a mechanism for maintaining contact of a solid phase of the phase change material with the one or more heat exchangers.Claim 12: The device according to Claim 11, wherein the mechanism includes a spring -loaded press, an actuator-driven press, one or more drainage holes, a fluid pump, or any combination thereof.Claim 13: The device according to any one of the preceding claims, further comprising a thermal diode providing unidirectional flow of the heat relative to the phase change material and preventing the phase change material from re -conditioning the one or more thermoelectric devices.Claim 14: The device according to any one of the preceding claims, further comprising a heat pipe extending between the one or more heat pumps and the phase change material, or between one or more heat exchangers, which are engaged with the one or more heat pumps, and the phase change material.Claim 15: The device according to any one of Claims 2 through 14, wherein the device is adapted to operate in: a) a cooling mode, whereby the phase change material and / or the fluid thermally communicate with the hot side of the one or more thermoelectric devices; and / or b) a heating mode, whereby the phase change material and / or the fluid thermally communicate with the cold side of the one or more thermoelectric devices.Claim 16: The device according to any one of the preceding claims, wherein the device is adapted to operate in: a) a first stage whereby the blood is heated or cooled from an initial physiological temperature to a target procedural temperature; and b) a second stage whereby the target procedural temperature is maintained in counteraction to a metabolic function of the patient and / or environmental effects upon the patient.Claim 17: The device according to Claim 16, wherein the phase change material and the fluid are operative in cooperation during the first and / or second stages; or the phase change material is operative without the fluid during the first stage and / or the second stage.Claim 18 : The device according to Claim 16 or Claim 17, wherein the fluid is operative without the phase change material during the first and / or the second stage.Claim 19: The device according to any one of Claims 16 through 18, wherein the phase change material is operative without the fluid during the first stage and the fluid is operative without the phase change material during the second stage.Claim 20: The device according to any one of Claims 16 through 19, wherein the fluid and the phase change material are arranged in parallel or in sequence relative to the one or more heat pumps, or one or more heat exchangers, which are engaged with the one or more heat pumps.Claim 21 : The device according to any one of Claims 2 through 20, wherein the one or more thermoelectric devices operate with a temperature delta, between the hot and cold sides, of about 0 °C to about 40 °C.Claim 22: The device according to any one of Claims 2 through 21, wherein the one or more thermoelectric devices include 3 or more up to 12 or even more thermoelectric devices.Claim 23: The device according to any one of the preceding claims, wherein a cooling load of the cold side is about 200 Watts to about 350 Watts, more preferably about 250 Watts to about 300 Watts, or even more preferably about 270 Watts to about 280 Watts; optionally more than about 350 Watts, such as up to about 30 kilowatts.Claim 24: The device according to any one of the preceding claims, wherein the blood is cooled or heated at a rate of about 0.1 °C / minute, more preferably about 0.3 °C / minute, more preferably about 0.5 °C / minute, more preferably about 0.7 °C / minute, or even more preferably about 0.9 °C / minute.Claim 25: The device according to any one of Claims 2 through 24, further comprising: a first heat exchanger thermally communicating with one of the hot side or the cold side of the one or more thermoelectric devices and with one or both of the phase change material and the fluid; and a second heat exchanger thermally communicating with the other of the hot side or the cold side of the one or more thermoelectric devices and with the tubing carrying the blood; and wherein the first heat exchanger and / or the second heat exchanger are removable from the thermoelectric device.Claim 26: The device according to Claim 25, wherein the second heat exchanger has a polygonal crosssection, and at least two sides of the polygonal cross-section are engaged with the one or more thermoelectric devices.Claim 27: The device according to Claim 26, wherein the second heat exchanger has a hexagonal crosssection, and each side thereof is engaged with at least one of the one or more thermoelectric devices.Claim 28: The device according to Claim 27, wherein the device further comprises a length of exchange tubing extending through the second heat exchanger, preferably, generally through a center of the second heat exchanger; and wherein the length of exchange tubing includes an inlet connection mechanism and an outlet connection mechanism to which the fluid circuit can connect; and optionally wherein the length of exchange tubing is fabricated from an electrically conductive material (e.g., a metallic material).Claim 29: The device according to any one of Claims 2 through 28, further comprising one or more temperature sensors including one or more of: a temperature sensor on or proximate to the length of exchange tubing, a temperature sensor at or proximate to an inlet of the blood circuit, a temperature sensor at or proximate to an outlet of the blood circuit, a temperature sensor at or proximate to the cold side, a temperature sensor at or proximate to the hot side, a temperature sensor associated with the fluid, and a temperature sensor associated with the phase change material.Claim 30: The device according to any one of the preceding claims, further comprising a pump for circulating the blood, preferably wherein the pump is separable from the device; and wherein the pumpeffectuates a blood flow of about 1 Liters / minute to about 10 Liters / minute; more preferably about 1 Liters / minute to about 7 Liters / minute.Claim 31 : The device according to any one of the preceding claims, further comprising one or more fluid moving devices for causing the fluid to flow.Claim 32: The device according to any one of the preceding claims, further comprising one or more blood flow rate sensors.Claim 33: The device according to any one of the preceding claims, further comprising a controller in signal communication with and for coordinating operation of the one or more heat pumps, the one or more fluid moving devices, the pump, the thermal diode, or any combination thereof based upon inputs from the one or more temperature sensors and / or the one or more blood flow rate sensors; wherein the temperature of the blood and / or a core body temperature of the patient is controlled via closed loop feedback.Claim 34: The device according to any one of the preceding claims, wherein the device is or is a module of an extracorporeal perfusion device.Claim 35: A method of operating the device according to any one of the preceding claims, the method comprising: optionally pre-charging the phase change material to a temperature at, above, or below the melting point of the phase change material; operating the device in the first stage whereby the blood is heated or cooled from the initial physiological temperature to the target procedural temperature; operating the device in the second stage whereby the target procedural temperature is maintained in counteraction to the metabolic function of the patient and / or environmental effects upon the patient; and wherein the phase change material and / or the fluid is operable during the first stage; and the phase change material and / or the fluid is operable during the second stage.Claim 36: The method according to Claim 35, wherein the phase change material and the fluid are operable during the first stage and the phase change material is operable without the fluid during the second stage; and wherein during the second stage, flow of the fluid is caused to cease.Claim 37: The method according to Claim 35, wherein the phase change material and the fluid are operable during the first stage and the fluid is operable during the second stage without the phase change material; wherein during the second stage, the phase change material is removed from the extracorporeal perfusion device or thermal communication of the one or more thermoelectric devices is otherwise interrupted; and optionally wherein a fluid moving device operates at a lower speed relative to the first stage.Claim 38: The method according to Claim 35, wherein the phase change material is operable during the first stage without the fluid and the fluid is operable during the second stage without the phase change material; wherein the fluid moving device operates at a higher speed in the first stage relative to the second stage.Claim 39: The method according to Claim 35, wherein the fluid is operable without the phase change material during the first stage and the second stage.Claim 40: The method according to any one of Claims 35 through 39, wherein each of the one or more thermoelectric devices are selectively activated or deactivated to maintain the target procedural temperature and / or when the temperature delta between the hot side and the cold side reaches or surpasses a threshold; and / or wherein power supplied to the one or more thermoelectric devices is modulated to maintain the target procedural temperature and / or when the temperature delta between the hot side and the cold side reaches / surpasses a threshold.Claim 41: The method according to any one of Claims 35 through 40, further comprising cooling the blood to no less than 30 °C, more preferably no less than 25 °C, more preferably no less than 20 °C, more preferably no less than 15 °C, or even more preferably no less than 4 °C.Claim 42: The method according to any one of Claims 35 through 41, wherein the first stage is operable for about 20 minutes to about 40 minutes.Claim 43: The method according to any one of Claims 35 through 42, further comprising operating the extracorporeal perfusion device in a third stage whereby the blood is cooled or heated from the target procedural temperature to a normal physiological temperature; wherein cooling or heating is caused by reversing the polarity of the one or more thermoelectric devices relative to the first and second stages, wherein the phase change material and / or the fluid is operable during said cooling or heating.Claim 44: The method according to any one of Claims 35 through 43, further comprising deactivating the thermal diode during said cooling or heating.Claim 45: The method according to any one of Claims 35 through 44, further comprising inducing hypothermia or hyperthermia in a patient.Claim 46: The method according to any one of Claims 35 through 45, further comprising swapping the one or more cannisters of the phase change material, during the procedure, respectively with one or more charged cannisters of the phase change material.

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