Patent Application
20140343640
Systems and methods for reducing the body temperature or inducing hypothermia are generally described.
According to a 1956 study published by the National Academy of Sciences (Dripps, R. D., Ed: The Physiology of Induced Hypothermia. Washington, D.C., National Academy of Science Publication 451, 1956), the metabolism of the human body decreases by about 8% for each degree Celsius the body's temperature is lowered, and at about 28° C., the body's metabolism is about 50% of its normal level. 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 patient. 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, a system for lowering the core body temperature of a patient is described. In some 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 constructed and arranged to deliver intubation gas to the patient. The system further comprises, in some embodiments, an intubation tube comprising an inlet end connected to the intubation gas outlet of the heat exchanger and an outlet end constructed and arranged to eject intubation gas into the airway of the patient. In some embodiments, the heat exchanger is constructed and arranged to cool the intubation gas, and the intubation gas outlet of the heat exchanger is positioned within 5 meters of the outlet end of the intubation tube.
In certain embodiments, a system is provided. In some 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 constructed and arranged to deliver intubation gas to the patient. In certain embodiments, the system comprises an intubation tube comprising an inlet end connected to the intubation gas outlet of the heat exchanger and an outlet end constructed and arranged to eject intubation gas into the airway of the patient. In some embodiments, the heat exchanger is constructed and arranged to cool the intubation gas, the intubation gas outlet of the heat exchanger is positioned within 5 meters of the outlet end of the intubation tube, and the system is configured for use in a method of lowering the core body temperature of a patient.
In one aspect, a method of lowering the core body temperature of a patient is described. In some embodiments, the method comprises positioning a heat exchanger within 30 cm of the mouth of the patient; and transporting an intubation gas through the heat exchanger such that the intubation gas is cooled, and at least a portion of the cooled intubation gas is transported to the lungs of the patient.
The method comprises, in some embodiments, transporting an intubation gas through a first lumen of an intubation tube and into the patient's lungs; transporting a liquid through a second lumen of the intubation tube; and atomizing the liquid at or near outlet discharge end of the second lumen such that liquid droplets are injected into the airway of the patient's lungs.
In one aspect, an intubation tube is provided. In some embodiments, the intubation tube comprises a first lumen; a second lumen; and an atomizer located at or near a discharge end of the second lumen, wherein the discharge end is configured to be inserted into an airway of a patient during use.
In some embodiments, the intubation tube comprises a first lumen; a second lumen; and a sensor integrated with the intubation tube and constructed and arranged to measure at least one of a temperature and a pressure at at least one location along the length of the intubation tube, wherein the intubation tube comprises a discharge end that is configured to be inserted into an airway of a patient during use.
The intubation tube comprises, in some embodiments, a first lumen containing and transporting a gas during use; and a second lumen containing and transporting a liquid during use, wherein a discharge end of the intubation tube is configured to be inserted into an airway of a patient during use.
In some embodiments, the intubation tube comprises a first lumen constructed and arranged to transport a first fluid; a second lumen constructed and arranged to transport a second fluid; and a third lumen constructed and arranged to transport a third fluid, wherein a discharge end of the intubation tube is configured to be inserted into an airway of a patient during use.
In certain embodiments, a liquid with a boiling point of less than about 37° C. for use in a method of lowering the core body temperature of a patient is provided. In some such embodiments, the method comprises transporting the liquid with a boiling point of less than about 37° C. to the lungs of the patient.
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 patient 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 patient (e.g. one suffering from fever or heat stroke) as well. In certain embodiments, the core body temperature of a patient can be lowered by using a heat exchanger. In certain such embodiments, the heat exchanger may be configured to transfer heat from an intubation gas to a coolant fluid prior to delivering the intubation gas to the patient (e.g., to the patient's lungs). In other embodiments, the heat exchanger may be configured to cool the intubation gas without the use of a coolant fluid (e.g., a solid-block heat exchanger, a Peltier cooler, etc.). The heat exchanger may be constructed and arranged such that it is located relatively closely to the entrance of the exit opening of the intubation tube used to deliver the intubation gas to the patient, which can ensure that the intubation gas is not excessively re-heated prior to entering the patient's body. In some embodiments, the intubation tube used to deliver cooled intubation gas to the patient can include one or more features facilitating patient cooling. For example, the intubation tube may in certain embodiments include multiple lumens. In some embodiments, one of the lumens can be used to deliver the intubation gas, while another lumen can be used to deliver a liquid such as a refrigerant. In some embodiments, a sensor can be integrated with the intubation tube, which can be used, for example, to determine a property of the fluid (e.g., temperature and/or pressure) while the fluid is in the patient's body. In certain embodiments, the intubation tube can include an atomizer that can be used to atomize a fluid (e.g., a refrigerant) exiting the intubation tube.
The injection of cooled gas into a patient'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 patient. In previous cooling systems, however, heat is removed from the intubation gas using a cooling device positioned at a location relatively far away from the patient's body, which leads to substantial re-heating of the cooled fluid before it reaches the lungs, thereby decreasing the efficacy of the system. In certain embodiments of the present invention, the inventive system may be configured so that a heat exchanger can be located relatively close to the patient's body and/or the exit opening of the conduit used to deliver the intubation fluid to the patient's lungs, thereby reducing the amount of heat that re-enters the intubation fluid prior to delivery to the patient's body.
In addition, it has been discovered in the context of the present invention that typical conventional intubation tubes are not ideally suited for patient cooling, and therefore, in certain embodiments of the invention, inventive intubation tubes are provided and used. Typical conventional intubation tubes generally include a first, single-lumen conduit for intubation gas delivery and a second, separate single-lumen conduit for transporting a gas to inflate a pilot balloon used to seal the lungs from the esophagus and stomach. In one aspect of the present invention, a single conduit intubation tube comprising multiple lumens is provided. In certain embodiments, at least two of the lumens are configured to deliver fluid to a patient's lungs. In certain, typical embodiments, at least one lumen of the intubation tube is not configured to deliver a fluid to the patient, but rather is configured to transport a gas to inflate a pilot balloon used to seal the lungs from the esophagus and stomach. As mentioned, in certain embodiments, the multi-lumen intubation tube may be configured to simultaneously deliver multiple fluids via separate lumens within the single conduit to the lungs of a patient. Delivering multiple fluids to the patient via separate lumens can, for example, allow one to simultaneously deliver an intubation gas and a cooling liquid without having to mix the two phases within the intubation tube. The multi-lumen intubation tube can also be configured to include a sensor(s) used to determine a property(ies) of a fluid within the intubation tube, for example during use. By incorporating the sensor into a lumen(s) of the intubation tube, as opposed to attaching the sensor to the exterior of the intubation tube, the risk of detachment from the intubation tube is reduced and more accurate property determinations may be possible.
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 patient (e.g., via an intubation tube). In
In some embodiments, in addition to the intubation gas, intubation tube 124 can be configured to deliver a liquid. For example, in some embodiments, intubation tube 124 can be configured to transport a liquid, such as a therapeutic liquid, or, in certain embodiments a refrigerant that can be vaporized within the patient to provide an additional cooling load. In
At least a portion of the liquid transported through the intubation tube may be atomized, in certain embodiments, prior to/upon being delivered to the patient. For example, in some embodiments, one or more atomizers positioned at or near the outlet end 128 of intubation tube 124 can be configured to atomize the liquid 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., perfluorocarbon droplets) between 1 micrometer and 5 micrometers in diameter. By dispersing the liquid in small droplets prior to/upon delivering it to the patient, 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 patient to which the liquid is delivered.
While the liquid from liquid source 144 is illustrated as being delivered directly to intubation tube 124 in
In some embodiments, the intubation gas outlet of the heat exchanger can be positioned relatively close to the outlet 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 patient. 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 refrigerant liquid, etc.) within the intubation tube can be measured, for example, prior to or as fluid is delivered to the patient. 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 fluid being delivered to a patient can allow one to adjust upstream system parameters as necessary to provide an effective cooling load to the patient. In certain embodiments, both a temperature and pressure are able to be measured by the sensor(s).
Intubation tube 124 can include one or more inventive features. In some embodiments, the intubation tube comprises a first lumen configured for transporting the intubation gas and a second lumen (which can be fluidically isolated from the first lumen along the length of the intubation tube) configured for transporting a liquid (e.g., a refrigerant or therapeutic agent containing liquid). In certain embodiments, the intubation tube can include one or more lumens for housing sensors such as temperature sensors or pressure sensors. In some embodiments, the intubation tube can include a lumen for transporting a fluid used to inflate a pilot balloon, which can be used to seal one cavity or passageway in the patient (e.g., the lungs) from another cavity or passageway in the patient (e.g., the esophagus, the stomach, etc.).
In
Referring back to the set of embodiments illustrated in
As one example, the sensor within lumen 218 can comprise a thermocouple configured to measure a temperature of a fluid within intubation tube 124. Other examples of temperature sensors that can be positioned within third lumen 218 include, but are not limited to, resistive temperature sensors, infrared sensors, bimetallic devices, change of state sensors, and the like. Examples of pressure sensors that can be positioned within third lumen 218 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 fourth lumen 220. Fourth lumen 220 can be configured to transport a gas for inflating a balloon or other flexible member (e.g., 222 in
An atomizer can be located near the outlet end of intubation tube 124, in some embodiments. The atomizer can be positioned relatively closely to the discharge end of a lumen (e.g., second lumen 212) used to transport a liquid (e.g., a refrigerant) through the intubation tube. For example, in some embodiments, an atomizer is positioned within 10 centimeters, within 5 centimeters, within 2 centimeters, within 1 centimeter, within 5 millimeters, within 1 millimeter, or substantially at the end of a lumen (e.g., second lumen 212 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 in 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.
The intubation gas delivered to the patient can comprise a variety of components. In some embodiments, the intubation gas comprises air or simulated air (i.e., a mixture of oxygen and nitrogen with an oxygen/nitrogen ratio of approximately a 20:80). In some embodiments, the intubation gas can be supplemented with helium, while in other embodiments, the intubation gas does not contain supplemental helium.
The heat exchanger coolant fluid can also include a variety of components. In some embodiments, the heat exchanger coolant fluid can comprise a liquid such as, for example, polyethylene glycol, methanol, glycerol, propylene glycol, ammonia, chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons. In other embodiments, the heat exchanger coolant fluid can comprise a gas (e.g., helium, oxygen, nitrogen, sulfur dioxide, and/or mixtures of these (e.g., air) or a liquefied gas (e.g. liquefied nitrogen).
A variety of liquids (e.g., from liquid source 144) may be transported through the intubation tube for delivery to the patient. In some embodiments, the liquid delivered to the patient comprises a refrigerant. In some embodiments, the liquid has a boiling point of less than about 37° C. For example, the liquid may comprise a perfluorocarbon. Examples of suitable perfluorocarbons with boiling points of less than about 37° C. include, but are not limited to, perfluoropropane (C3F8), and perfluorobutane (C4F10), perfluoropentane (C5F12). The use of refrigerants with relatively low boiling points can be advantageous, as the liquids can be delivered to the patient in the form of a liquid and evaporated within, for example, the lungs, where the gasified liquid can be subsequently exhaled. In addition, in embodiments in which the refrigerant is evaporated within the patient, the latent heat of vaporization of the refrigerant can supply an additional cooling load to the patient. However, the invention is not limited to the use of liquids with low boiling points, and, in some embodiments, liquids with boiling points of greater than about 37° C. can be transported through the intubation tube and delivered to the patient. Exemplary liquids with boiling points of greater than about 37° C. that can be transported through the intubation tube and delivered to the patient include, but are not limited to, perfluorohexane (C6F14) and the like.
While use of system 100 illustrated in
While the intubation tubes illustrated in
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 patient. 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.
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, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, 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 Ser. No. 61/526,375, filed Aug. 23, 2011, and entitled “Systems and Methods for Reducing Body Temperature,” which is incorporated herein by reference in its entirety for all purposes.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US12/52055 | 8/23/2012 | WO | 00 | 5/27/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61526375 | Aug 2011 | US |
