Patent Application
20140350648
Systems and methods for reducing body temperature or inducing hypothermia are generally described.
Reducing the body's metabolism can decrease the amount of damage that metabolically active organs (e.g., the heart, the brain, etc.) sustain during ischemic and/or hypoxic events such as heart attacks and strokes. Accordingly, deliberate lowering of body temperature (i.e., inducing hypothermia) has been used in a variety of medical procedures including heart surgery, brain surgery, spinal surgery, organ transplantation procedures, and the like.
A variety of methods for lowering body temperature and inducing hypothermia are known in the art. Known methods include, for example, applying cold cloth or sponges to the body, applying ice packs to the body, submerging the body in cold fluid, and transporting a cooled gas mixture including helium to the lungs of the subject. Despite the benefits provided by the systems and methods known in the art, additional performance enhancements would be desirable.
Systems and methods for reducing body temperature, e.g. for inducing hypothermia, are described. The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.
In one aspect, an intubation tube is provided. In certain embodiments, the intubation tube comprises a first lumen comprising an inlet end and a discharge end; a second lumen comprising an inlet end and a discharge end; and a valve associated with the first lumen configured to restrict the flow of fluid from outside the intubation tube into the discharge end of the first lumen and to allow fluid to flow from inside the first lumen out of the discharge end of the first lumen.
The intubation tube comprises, in some embodiments, a lumen comprising an inlet end and a discharge end; and a heat exchanger lumen associated with the first lumen, the heat exchanger lumen comprising a fluidic pathway configured to transfer heat from the first lumen out of the intubation tube.
In another aspect, a system for lowering the core body temperature of a subject is provided. In certain embodiments, the system comprises a heat exchanger comprising an intubation gas inlet fluidically connected to a source of intubation gas, and an intubation gas outlet, wherein the heat exchanger is configured to cool intubation gas passing through the heat exchanger. In some embodiments, the system comprises an intubation tube fluidically connected to the intubation gas outlet of the heat exchanger and fluidically connected to a source of a coolant having a boiling point of greater than about 37 degrees Celsius, the intubation tube comprising a discharge end configured to eject intubation gas into the airway of the subject.
In certain embodiments, a system for lowering the core body temperature of a subject comprises a heat exchanger comprising an intubation gas inlet fluidically connected to a source of intubation gas, and an intubation gas outlet, wherein the heat exchanger is configured to cool intubation gas passing through the heat exchanger. In some embodiments, the system comprises an intubation tube comprising a first lumen fluidically connected to the intubation gas outlet of the heat exchanger, the first lumen comprising a discharge end configured to eject intubation gas into the airway of the subject, and a valve positioned at or near the discharge end of the first lumen configured to restrict the flow of fluid from outside the intubation tube into the discharge end of the first lumen and to allow fluid to flow from inside the first lumen out of the discharge end of the first lumen.
In another aspect, a method of lowering the core body temperature of a subject is provided. The method comprises, in certain embodiments, transporting an intubation gas through a heat exchanger such that the intubation gas is cooled, and at least a portion of the cooled intubation gas is transported through an intubation tube to an airway of the subject; and transporting a coolant with a boiling point of greater than about 37 degrees Celsius through the intubation tube to the airway of the subject.
Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control.
Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:
Systems and methods for lowering the core body temperature of subject are generally described. While most of the discussion below focuses on the application of inducing hypothermia, it should be understood that certain embodiments of the invention may be used/practiced for reducing the core body temperature of a hyperthermic subject (e.g. one suffering from fever or heat stroke) as well. In certain embodiments, the core body temperature of a subject can be lowered by using a heat exchanger configured to cool an intubation gas that is transported to the subject via an intubation tube. The intubation tube used to deliver cooled intubation gas to the subject can include one or more features facilitating cooling of the subject. For example, in certain embodiments, the intubation tube may include multiple lumens. In some embodiments, one of the lumens can be used to deliver the relatively cool intubation gas and a second lumen can be used to transport relatively warm gas away from the patient's lungs. In certain embodiments, the system can be configured such that a fluid comprising water (e.g., in the form of ice particles and/or liquid mist) can be delivered to the subject via the intubation tube, which can provide an enhanced cooling effect.
The injection of cooled gas into a subject's lungs to decrease body temperature is known in the art. For example, U.S. Pat. No. 6,983,749 to Kumar et al. describes a method of lowering body temperature by transporting a cooled gas mixture including helium into the lungs of the subject. In previous cooling systems, however, the intubation gas is often not effective in achieving the desired level of cooling. For example, in certain previous systems, perfluorocarbons are transported to the subject's lung in order to effect cooling, which can provide effective cooling in part due to their low boiling point and associated latent heat of vaporization. However, perfluorocarbons have a number of shortcomings. For example, perfluorocarbons are generally very expensive (e.g., over $500 per liter). Gases such as helium can be used as a replacement, but helium may not in certain instances provide sufficient cooling. Described herein are inventive systems and methods that are, in certain embodiments, able to provide effective cooling using fluids with boiling points greater than about 37° C., such as water.
It has also been discovered, in the context of the present invention, that typical conventional intubation tubes are not ideally suited for subject cooling, and therefore, in certain embodiments of the invention, inventive intubation tubes are provided and used. In typical previous cooling systems, the intubation tube includes a single lumen that is used to transport the cooled gas into the subject and to transport gas warmed within the subject's lungs out of the subject's body. When a single lumen is used to transport gas into and out of the subject, a rewarming effect is generally observed, which can negate much if not all of the cooling effect. Specifically, it is believed that the cooled intubation gas entering the subject remixes with warm air being transported away from the airway of the subject, thereby re-heating the cooled intubation gas. In certain embodiments of the present invention, the intubation tube used to deliver cooled intubation gas to the subject can include multiple lumens. In some embodiments, a first lumen can be used to deliver the relatively cool intubation gas and a second lumen can be used to transport relatively warm gas away from the patient's lungs. By isolating the cooled gas from the relatively warm return gas, one can limit the extent to which the cooled fluid is reheated prior to reaching the lungs of the subject, thereby providing an enhanced cooling effect.
In some embodiments, the heat exchanger can be configured such that, once the intubation gas has been cooled, the intubation gas is delivered to the subject (e.g., via an intubation tube). In
The intubation gas can be cooled within the heat exchanger using a variety of suitable methods. In
In some embodiments, in addition to the intubation gas, intubation tube 124 can be configured to deliver a supplemental coolant. For example, in some embodiments, intubation tube 124 can be configured to transport a supplemental coolant having a boiling point of greater than about 37 degrees Celsius. In certain embodiments, at least a portion of the supplemental coolant can undergo a phase change (e.g., melting, vaporization, etc.) within the subject to provide an additional cooling load.
The intubation gas and/or the supplemental coolant delivered to the subject can comprise a variety of components. In some embodiments, the intubation gas and/or the supplemental coolant comprises air or simulated air (i.e., a mixture of oxygen and nitrogen with an oxygen:nitrogen ratio of approximately a 20:80). In certain embodiments, the intubation gas and/or the supplemental coolant is substantially free of supplemental helium (e.g., the intubation gas and/or the supplemental coolant can contain helium in an amount of less than about 1%, less than about 0.1%, less than about 0.01% by volume, or can contain helium in an amount of 0% by volume). In some embodiments, the intubation gas and/or the supplemental coolant is substantially free of perfluorocarbons (e.g., the intubation gas and/or the supplemental coolant can contain perfluorocarbons in an amount of less than about 1%, less than about 0.1%, less than about 0.01% by volume, or can contain perfluorocarbons in an amount of 0% by volume). The ability to operate without the use of supplemental perflourocarbon(s) and/or supplemental helium can reduce system complexity and cost and allow one to avoid introducing compounds into the airway of the subject that are not naturally present within the subject. Of course, one of ordinary skill in the art would understand that the invention is not limited to such embodiments, and in other cases, one or more supplemental perfluorocarbons and/or supplemental helium could be employed.
As noted elsewhere, the supplemental coolant can contain a component having a boiling point of greater than 37° C. In one particularly advantageous set of embodiments, the supplemental coolant comprises H2O. The H2O can be in solid and/or liquid form. For example, in certain embodiments, the H2O comprises ice, such as ice particles injected or otherwise transported into and/or within the intubation tube. In certain embodiments, the H2O comprises liquid water. Liquid water can be transported into the intubation tube in the form of, for example, a mist of water droplets, a substantially continuous stream of water, or any other suitable form. In certain embodiments, the supplemental coolant can be added to the intubation tube and/or the heat exchanger in the liquid phase and can freeze within the intubation tube and/or the heat exchanger to form a solid phase (e.g., solid particles) prior to being delivered to the subject.
In certain embodiments, one or more salts or other additives can be included in the supplemental coolant (e.g., included in liquid water, solid ice, and/or any other suitable supplemental coolant), which can lower the freezing point of the supplemental coolant, thereby decreasing the temperature at which the desired phase change occurs and providing more effective cooling. Examples of suitable salts that can be included in the supplemental coolant include, for example, chloride salts (e.g., sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), magnesium chloride (MgCl2)) and the like.
Supplemental coolant can be added to the intubation tube, to the heat exchanger (e.g., to the intubation gas inlet), or at any other suitable point in the system. For example, in the set of embodiments illustrated in
The supplemental coolant can also be delivered to the system at locations upstream of the location on the intubation tube that is fluidically connected to the intubation gas outlet of the heat exchanger, in addition to or in place of other delivery locations. For example, the supplemental coolant from source 144 can be transported to an inlet of heat exchanger 110 via conduit 152. In some such embodiments, the supplemental coolant can be transported through and cooled within the heat exchanger (e.g., heat exchanger 110 and/or another heat exchanger) prior to being transported to intubation tube 124. In some such embodiments in which heat exchanger 110 is used to pre-cool the supplemental coolant from source 144, heat exchanger 110 can comprise a separate coolant inlet and a separate coolant outlet for the supplemental coolant to be delivered to the subject. In some such embodiments, the supplemental coolant can be transported through heat exchanger 110 via a separate conduit which can, for example, be surrounded by second conduit 134 of heat exchanger 110.
In certain embodiments, supplemental coolant can be atomized prior to being transported to intubation tube 124. For example, in
In one particular set of embodiments, a supplemental coolant comprising water can be used to generate ice particles for delivery to the subject via the intubation tube. For example, source 144 can comprise a container (e.g., a tank) in which water, saline, or other water-containing coolant is stored. The water-containing coolant can then be transported along conduit 152 for transport to an inlet of heat exchanger 110 (e.g., intubation gas inlet 112 or another heat exchanger inlet dedicated to receiving supplemental coolant). In certain embodiments, a programmable dispenser can be used, which can deliver a predetermined volume of water-containing coolant to the heat exchanger (e.g., for each cycle in a series of cycles). In certain embodiments, a mist of water-containing coolant can enter the heat exchanger in liquid form (e.g., at about 90° C.). In some embodiments, the water-containing mist within heat exchanger 110 can be cooled to below 0° C., thereby forming ice-containing particles. The ice-containing particles can subsequently be transported to an inlet of intubation tube 124 (e.g., the inlet through which intubation gas is transported into intubation tube 124 or another inlet (e.g., of a fluidically separated lumen) dedicated to receiving supplemental coolant). Of course, supplemental water-containing coolant can also be delivered directly to intubation tube 124 along conduit 150, in addition to or in place of the delivery along conduit 152. In some such embodiments, the water-containing coolant can be atomized at the discharge end of conduit 150 and, in some cases, form ice particles within intubation tube 124.
Supplemental coolant from source 144 can be transported through intubation tube 124 and delivered to the lungs via a lumen within intubation tube 124, as described in more detail below. In some embodiments, the system is configured to inject the intubation gas and the supplemental coolant (e.g., with a boiling point of greater than about 37 degrees Celsius) into a single lumen of intubation tube 124. In other embodiments, the system is configured to inject the intubation gas into one lumen of intubation tube 124 and to inject the supplemental coolant into a different lumen of intubation tube 124. For example, the lumen within intubation tube 124 that is used to deliver the supplemental coolant can be isolated from the lumen in intubation tube 124 used to deliver the intubation gas, in some cases, along substantially the entire length of the intubation tube.
In some embodiments in which the supplemental coolant is provided to the intubation tube in liquid form, at least a portion of the liquid supplemental coolant transported through the intubation tube may be atomized prior to and/or upon being delivered to the subject. For example, in some embodiments, one or more atomizers positioned at or near discharge end 128 of intubation tube 124 can be configured to atomize the supplemental coolant as it is ejected from the intubation tube. In one particular set of embodiments, the atomizers can comprise nozzles comprising 100 micrometer openings configured to produce liquid droplets (e.g., liquid water droplets) between 1 micrometer and 5 micrometers in diameter. By dispersing the liquid in small droplets prior to/upon delivering it to the subject, the speed at which the liquid is evaporated can be increased, which can lead to more rapid or effective cooling of the region of the subject to which the liquid is delivered.
In some embodiments, the inlet end of the intubation tube (e.g., the inlet end of a lumen of the intubation tube) can be positioned relatively close to the intubation gas outlet of the heat exchanger. For example, as illustrated in
In some embodiments, the intubation gas outlet of the heat exchanger can be positioned relatively close to the discharge end of the intubation tube. For example, in
In certain embodiments, the heat exchanger used to cool the intubation gas can be positioned a short distance from the mouth of the subject. For example, in the set of embodiments illustrated in
In some embodiments, at least one of the temperature and the pressure of a fluid (e.g., the intubation gas, a supplemental coolant, etc.) within the intubation tube can be measured, for example, prior to or as coolant is delivered to the subject. Measurement of a temperature or pressure can be achieved using, for example, one or more sensors integrated with the intubation tube, as described in more detail below. The ability to measure the temperature or pressure of a coolant being delivered to a subject can allow one to adjust upstream system parameters as necessary to provide an effective cooling load to the subject. In certain embodiments, both a temperature and pressure are able to be measured by the sensor(s).
In addition to inventive systems and methods for body temperature reduction, inventive intubation tubes are also described. In some embodiments, the intubation tube comprises a first lumen comprising an inlet end and a discharge end and a second lumen comprising an inlet end and a discharge end. In certain embodiments, the first lumen can be configured for transporting intubation gas from outside the subject to the airway of the subject, and the second lumen can be configured to transport fluid from the subject's airway to a location outside the subject. For example, in certain embodiments, the intubation tube can be configured such that fluid exiting the airway of the subject is restricted from being transported through the first lumen and thereby transported through the second lumen, while fluid (e.g., intubation gas) being transported to the airway of the subject is allowed to be transported through the first lumen.
Directionally selective transportation of fluids through the intubation tube can be achieved using a valve. In certain embodiments, the intubation tube comprises a valve associated with the first lumen. The valve can be configured to restrict the flow of fluid from outside the intubation tube (e.g., within the subject's airway) into the discharge end of the first lumen. In certain embodiments the valve can be configured to allow fluid to flow from inside the first lumen out of the discharge end of the first lumen (e.g., into the subject's airway). In this way, the valve can ensure that fluid is transported through the first lumen only in one direction (e.g., from outside the subject to the subject's airway).
Intubation tube 124 can further comprise valve 214. Valve 214 can be associated with first lumen 210 and configured to restrict the flow of fluid from outside intubation tube 124 into the discharge end of first lumen 210. In addition, valve 214 can be configured to allow fluid to flow from inside first lumen 210 out of the discharge end of first lumen 210. Valve 214 can be positioned at any suitable point in or near intubation tube 124. In certain embodiments, valve 214 is positioned within first lumen 210. In some embodiments, valve 214 can be positioned at or near the discharge end 128 of intubation tube 124. For example, in the set of embodiments illustrated in
Valve 214 can be arranged in any suitable fashion. For example, in certain embodiments, valve 214 is configured to at least partially cover the discharge end of first lumen 210 to restrict the flow of fluid from outside intubation tube 124 into first lumen 210 and to at least partially uncover the discharge end of first lumen 210 to allow fluid to flow from inside first lumen 210 out of the discharge end of first lumen 210. One such valve is illustrated in
Valve 214 can inhibit mixing of the cooled intubation gas (and/or supplemental coolant) with the re-warmed gas exhaled from the subject's airway. This can inhibit premature re-heating of the cooled fluid delivered to the subject's airway, enhancing the cooling effect.
In certain embodiments, mixing of the cooled intubation gas and the re-heated fluid exhaled from the airway can be further inhibited by isolating lumen 210 from lumen 212 along at least a portion of the length of intubation tube 124 such that the contents of the lumens do not mix or do so only to a limited extent. In
In certain embodiments, first lumen 210 can contain, flowing therethrough, a first fluid, and second lumen 212 can contain flowing therethrough a second fluid that is warmer than the first fluid. For example, in certain embodiments, lumen 210 can be configured to transport intubation gas, supplemental coolant (e.g., ice, liquid water, etc.), and/or another component used to lower the body temperature of the subject. In certain embodiments, lumen 212 can be configured to transport fluid that is being exhaled from the subject, which can be warmed within the airway of the subject during cooling of the subject.
The intubation gas and the supplemental coolant (e.g., including a water-containing liquid, ice-containing particles, etc.) can be transported to the subject within a single lumen, in certain embodiments. For example, in the set of embodiments illustrated in
Lumen 216 can be used to transport a liquid such as liquid water and/or a solid such as ice particles (e.g., in combination with a carrying fluid). In certain embodiments, lumen 216 includes an atomizer at or near the discharge end of lumen 216, which can be used to atomize a liquid (e.g., liquid water, optionally including a freezing point depressant such as a salt or any other suitable liquid) that is transported out of lumen 216 prior to entry into the subjects airway. Optionally, intubation tube 124 can include one or more additional lumens for transporting additional coolants.
In
Referring back to the set of embodiments illustrated in
The measurement made by the sensor within lumen 222 can be used to adjust a parameter within the system. For example, in certain embodiments, system 100 (in which intubation 124 can be used) is configured to adjust a flow rate and/or a temperature of the intubation gas and/or the supplemental coolant at the inlet end of intubation tube 124 based at least in part on the temperature and/or pressure determination made by the sensor(s) within lumen 222. As one particular example, a temperature sensor within lumen 222 can be used to measure the temperature of the coolant exiting the discharge end of lumen 210. If the gas exiting lumen 210 is too cold, system 100 can increase the temperature of the intubation gas and/or supplemental coolant and/or system 100 can lower the flow rate of the intubation gas and/or supplemental coolant transported through lumen 210. If the gas exiting lumen 210 is too warm, system 100 can reduce the temperature of the intubation gas and/or supplemental coolant and/or system 100 can increase the flow rate of the intubation gas and/or supplemental coolant transported through lumen 210.
Examples of temperature sensors that can be positioned within lumen 222 include, but are not limited to, thermocouples, resistive temperature sensors, infrared sensors, bimetallic devices, change of state sensors, and the like. Examples of pressure sensors that can be positioned within lumen 222 include, for example, piezoresistive strain gauges, capacity pressure sensors, electromagnetic pressure sensors, piezoelectric pressure sensors, optical pressure sensors, potentiometric pressure sensors, resonant pressure sensors, thermal pressure sensors, and the like. In some embodiments, electrochemical sensors (e.g., pH sensors), fiber optic sensors, and/or glucose sensors can be positioned within a lumen of the intubation tube. While a single lumen for housing a sensor is illustrated in
In some embodiments, intubation tube 124 comprises an additional lumen (not illustrated in
The intubation tubes described herein can be manufactured using a variety of methods. For example, in some embodiments, the intubation tube can be formed by extruding a material, such as a polymeric material, through a die to produce one or more tubes with multiple lumens. In some embodiments, multiple tubes can be attached (e.g., adhered or bonded). In some embodiments, first and second materials can be co-extruded such that the first material occupies the space defined by the material body and the second material occupies the space defined by the lumens. The second material can then be removed from the co-extruded body to form the final intubation tube structure. The intubation tubes described herein can be fabricated, in some embodiments, using hot melt tunneling, by forming a material (e.g., a melted polymer) over pre-positioned sensors or tubes, or any other methods known to those of ordinary skill in the art.
The material body of the intubation tube can be formed using a variety of materials. For example, in some embodiments, the material body of the intubation tube comprises one or more polymers (e.g., polyurethane, silicone, poly(vinyl chloride), polypropylene, polyethylene, polyesters, and/or polyamides), metals (e.g., copper, aluminum, and the like), or combinations of two or more of these materials.
Referring back to
The conduits of the heat exchanger can be formed from a variety of materials. In some embodiments, the inner conduits include materials with relatively high thermal conductivities to enhance the rate at which heat is transferred between the coolant fluid and the intubation gas. For example, all or part of the inner conduits can be formed of a metal or metals such as aluminum, copper, steel (e.g. stainless steel), titanium, alloys of these or other metals, and the like.
While three inner conduits are illustrated in
Fluid may be transported through heat exchanger 110 according to a variety of configurations. In some embodiments, the intubation gas and the coolant fluid can be flowed through heat exchanger 110 in a co-current flow configuration. In other embodiments, the coolant fluid and the intubation gas can be transported through the heat exchanger 110 in a counter-current configuration. In addition, one or more baffles, fins, or other fluid-directing components may be integrated into one or more conduits within heat exchanger 110 to direct the flow of fluid.
It should be understood that a standalone heat exchanger (e.g., heat exchanger 110 in FIGS. 1 and 3A-3D) is not required for operation of the system. In certain embodiments, for example, intubation tube 124 comprises a heat exchanger. The heat exchanger can be integrated with intubation tube 124 such that, during use, at least a portion of the heat exchanger is positioned within the airway of the subject. The integrated heat exchanger of intubation tube 124 can be used in place of or in addition to stand alone heat exchanger 110.
In some embodiments, the heat exchanger of the intubation tube comprises a fluidic pathway configured to transfer heat from a lumen of the intubation tube (e.g., from an intubation gas and/or a supplemental coolant within a lumen) out of the intubation tube. By arranging the heat exchanger in this manner, the intubation gas and/or supplemental coolant can be cooled as it is transported through the intubation tube.
The heat exchanger of the intubation tube can be arranged in a variety of configurations. In some embodiments, the heat exchanger can comprise one or more lumens through which a heat exchanger coolant fluid can be transported. In certain embodiments, the intubation tube can be configured to include at least one lumen that transports heat exchanger coolant fluid. In certain arrangements, the intubation tube can be configured to transport heat exchanger coolant fluid from an inlet end of the intubation tube to a location at or near the discharge end of the intubation tube. In some embodiments, the intubation tube can be configured such that when the heat exchanger coolant fluid reaches a location at or near the discharge end of the intubation tube the direction of flow of the heat exchanger coolant fluid is altered such that the heat exchanger coolant fluid is returned towards or to the inlet and of the intubation tube.
For example, in certain embodiments, the fluidic pathway of the heat exchanger comprises a jacket surrounding at least a portion of the lumen of the intubation tube. In some embodiments, the intubation tube heat exchanger can be in the form of a separate lumen associated with the intubation tube.
Heat exchange can be achieved, for example, by transporting a heat exchanger coolant into and out of the fluidic pathway of the heat exchanger. Any suitable heat exchanger fluid could be used within the integrated heat exchanger, including, for example, polyethylene glycol, methanol, glycerol, propylene glycol, ammonia, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, helium, oxygen, nitrogen, sulfur dioxide, a liquefied gas (e.g. liquefied nitrogen) and/or mixtures of these (e.g., air). In certain embodiments, the heat exchanger fluid within intubation tube 124 has a freezing point lower than about 0° C. or lower than about −15° C. (e.g., about −20° C.).
In some embodiments, the heat exchanger can be an integrated part of the intubation tube, such that the heat exchanger and the intubation tube form a monolithic structure. In other embodiments, the heat exchanger can be formed separately from the intubation tube and subsequently associated with the intubation tube (e.g., via an adhesive, mechanical fasteners, or other suitable attachment or by coiling tubing for carrying the heat exchanger coolant around the intubation tube, etc.).
To ensure that the heat exchanger coolant fluid is not delivered to the airway of patient, the fluidic pathway of the heat exchanger coolant fluid may be sealed at the discharge end of tube 400. The discharge end of the heat exchanger coolant fluid pathway can be sealed by integrally forming (e.g. via injection molding) a wall (not shown) at the discharge end of the intubation tube that prevents liquid discharged from lumen 420 and/or 422 from being discharged from the discharge end of the intubation tube, while not preventing discharge from lumen 410, in some embodiments. In certain embodiments, the discharge end of the heat exchanger coolant fluid pathway can be sealed by positioning a cap at the discharge end of the intubation tube. An exemplary cap 440 is illustrated in
While intubation tube 400 is illustrated as including a single lumen for the delivery of intubation gas or other intubation fluids, in other embodiments, the intubation tube comprising a heat exchanger can include multiple lumens for the delivery of intubation gas or other intubation fluids. For example,
Of course, in other embodiments, a standalone heat exchanger (e.g., heat exchanger 110 in
While the systems herein have been described primarily for use with a human subject, it should be understood that in other embodiments non-human subjects can be used. For example, systems such as those described and outlined in
While intubation tubes have been described primarily for use in association with the systems and methods for lowering the core body temperature of a subject, as described elsewhere herein, use of the intubation tubes described herein is not so limited, and one of ordinary skill in the art would recognize that the intubation tubes described herein can be used in a variety of other systems and for a variety of other purposes, particularly where it is advantageous to deliver both a gas and a supplemental coolant (e.g., a coolant having a boiling point of greater than about 37 degrees Celsius) to the airway of a subject and in situations where pressure or temperature monitoring of a fluid delivered to the subject is desired.
The articles, systems, and methods described herein can be used in association with a variety of procedures in which it is useful to lower the body temperature of a subject. For example, the articles, systems, and methods described herein can be used to reduce the adverse impacts of reduced oxygen availability during a variety of ischemic events including, but not limited to, cardiac arrest, stroke, traumatic brain or spinal cord injury, neurogenic fever, and neonatal encephalopathy. The articles, systems, and methods described herein can also be used to treat, for example, heat stroke.
U.S. Provisional Patent Application No. 61/576,645, filed Dec. 16, 2011, and entitled “Body Temperature Reduction Systems and Associated Methods” is incorporated herein by reference in its entirety for all purposes.
The following example is intended to illustrate certain embodiments of the present invention, but does not exemplify the full scope of the invention.
This example describes transpulmonary evaporative cooling in swine using a mircoparticle cold air/ice mist to effectively induce therapeutic hypothermia. Thermoelectric induced cold mist was shown to promote swift heat extraction from blood circulating through the lungs. The result was the rapid lowering of the core temperature, using the lungs as heat exchange organs.
One female pig (Chester White, Swine), weighing 91 kg was used in this set of experiments. The temperature of the environment in which the experiments were performed was set to 70-72° F. Anesthesia was induced using intramuscular injections of ketamine (10 mg/kg) and xylazine (1 mg/kg). Following induction of anesthesia, peripheral intravenous catheters were inserted and lactated Ringers solution was infused at 125 ml/hour. The general anesthesia was deepened with thiopental (3 mg/kg) and pancuronium (0.1 mg/kg).
After the onset of neuromuscular paralysis, a specially designed intubation tube with an inside wall cooling track (similar to the intubation tube illustrated in
The fluid within the intubation tube was cooled using a heat exchanger similar in configuration to the heat exchanger illustrated in FIGS. 1 and 3A-3D. The heat exchanger system could be both volume controlled and pressure controlled, with varying rates of free gas flow. The inspiratory limb of the breathing circuit was connected in series to the heat exchanger, which was capable of cooling the inspiratory gases to −25° C.
The pig was ventilated with oxygen-enriched room air (FiO2 0.21-0.4) so as to maintain arterial oxygen saturation above 90%, a tidal volume of 6-10 ml/kg, and a respiratory rate of 12-16 breaths per minute to maintain a PaCO2 of 35-40 torr. Total intravenous anesthesia was maintained with propofol (1 mg/kg bolus, followed by an infusion of 75 μg/kg/minute), fentanyl (25 mg/kg bolus, followed by an infusion of 0.1-0.3 μg/kg/minute), and pancuronium (0.1 mg/kg/hour). Radiant heating lamps and warming blankets were used to maintain normothermia until the induction of hypothermia.
The pig was monitored using: EKG, pulse oximeter, blood pressure cuff, arterial line, pulmonary artery catheter and Foley catheter. Temperature probes were inserted into the rectum, ear, nasopharynx and esophagus in addition to thermistors already incorporated in the pulmonary artery catheter and Foley catheter. A fiberoptic transducer tipped pressure/temperature catheter was introduced into the brain parenchyma through a small right parietal bore hole for intracranial pressure and temperature measurements. The concentration of oxygen in the inspired gas mixture was adjusted as needed to avoid hypoxemia (SaO2<90%).
While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present invention.
The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”
The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.
As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.
As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 61/576,645, filed Dec. 16, 2011, and entitled “Body Temperature Reduction Systems and Associated Methods,” which is incorporated herein by reference in its entirety for all purposes.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2012/069765 | 12/14/2012 | WO | 00 | 6/13/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61576645 | Dec 2011 | US |
