Apparatuses and methods for cooling specific tissue

REFERENCE TO RELATED APPLICATIONS

0001This application is a continuation of International Application No. PCT/US2011/028475, filed Mar. 15, 2011, pending, which claimed the benefit of U.S. Provisional Patent Application No. 61/313,865, filed Mar. 15, 2010, abandoned, each of which is herby incorporated by reference.

0002The present disclosure concerns apparatuses and methods useful for providing cooling to particular tissues or body parts. In particular, it concerns a faster, less complicated system and techniques for cooling internal tissues or organs, such as the brain, so as to reduce or limit damage.

BACKGROUND

0003Therapeutic hypothermia, i.e. lowering a patient's body temperature, has been used as a treatment to help reduce the risk of the ischemic injury to tissue following a period of insufficient blood flow, e.g. following a cardiac arrest or stroke. Different systems and methods for inducing such hypothermia have been proposed, such as submersion or enclosure of the body in a cooling bath or wrap, or by routing blood flow out of the body and through a cooling device. In other systems, external cooling of the head through placement of a cap, helmet or collar with cooling mechanisms or flow is proposed. Other approaches have included spraying a volatile liquid perfluorocarbon coolant into the nasal cavity, with evaporation of the coolant decreasing the temperature in the head, or expanding a balloon against internal airway tissues, e.g. with cold liquid.

0004However, such systems for cooling are not optimal for the purpose of cooling the brain or other specific tissues. Whole-body cooling by way of a bath or wrap risks damage to skin, muscle or other tissues if not carefully administered. It also requires bulky or relatively large devices to cover the body, and overuses cooling insofar as generally the entire body need not be subjected to hypothermia in order to treat the brain or other localized tissues. Routing blood through an external cooling device requires not only sophisticated equipment but also can only be done for a limited time, e.g. the amount of time a patient can sustain a cardiopulmonary bypass. External cooling of the head requires an external fitting that generally must fit closely with the patient's head and/or neck, requiring a number of sizes or adjustability for different patients. It can have also substantial inefficiencies in cooling because of its exposure to the ambient environment. Use of a volatile coolant within the body can present difficulties in terms of monitoring potential toxicity levels of the coolant and ensuring that the coolant remains in parts of the body that will tolerate it. A balloon that seals the airway may not be usable over significant time periods due to its interference with the patient's breathing.

0005Accordingly, new devices and methods for applying cooling to specific tissues, for example to treat the brain and protect it from adverse effects arising from lack of blood flow (e.g. stroke or cardiac arrest) or from traumatic injury, are needed.

SUMMARY

0006The present disclosure includes, among other things, an apparatus that includes a source of coolant consisting essentially of compressed breathable gas and a delivery tube having a proximal end connected to the source of coolant. When gas is released from the source into the proximal end of the delivery tube, the gas cools adiabatically, and the delivery tube is configured such that the gas passes through the delivery tube without substantial gain of thermal energy, e.g. without gaining more than 20 Celsius degrees, or more than about 1 to 5 Celsius degrees, in temperature. At least one insertion tube is connected to the delivery tube and extends to a free end having an opening. The insertion tube(s) are sized and configured to be inserted into a patient's nose so that the free end is positioned in the patient's airway beyond the anterior turbinate area of the patient's nose, and so the gas passes the mucosa and conchae of the nose before exiting the insertion tube(s). The gas experiences no further cooling between the proximal end of the delivery tube and the at least one insertion tube.

0007In some embodiments, the source of gas is a canister of compressed breathable gas, which may be portable by hand (e.g. small medical-use canister), or a non-portable stand-alone tank. A mask may be provided to cover at least the patient's nose and to be held to the patient's head, so that at least one of the delivery tube and insertion tube(s) extend through the mask with the mask resting against the patient's face when the at least one insertion tube is inserted into the patient's nose. The noted configured condition of the delivery tube may include the length of the delivery tube being about one foot or less, the material of the delivery tube being of insulation (e.g. foam insulation), and/or the delivery tube having an outer layer of insulation. The source of gas may be more than one compressed gas canister, e.g. two compressed gas canisters with a Y-shaped connector connected to the delivery tube and to each of the canisters. A two-way stopcock may be connected to each of the canisters and to the delivery tube.

0008In other embodiments, a system for cooling the brain with compressed gas disclosed, which can include a supply of a compressed breathable gas for thermal transfer with tissues in a patient's head, with the gas provided in at least one canister initially at a first pressure greater than atmospheric pressure. A set of first and second nasal tubes each for insertion into a respective nostril of a patient may each have a respective distal end with a respective hole, and be sized and configured so that when they are fully inserted into the patient, their respective distal ends are positioned in one or more of the choanae of the patient. A delivery tube connects the canister(s) with the nasal tubes and may be configured such that gas traveling along the delivery tube remains at approximately the same temperature along the tube. As the gas enters the delivery tube, the gas is cooled adiabatically to a first temperature below room temperature. The gas flows through the delivery tube and nasal tubes without any added liquid to exit the respective holes of the nasal tubes at approximately the first temperature, to cool tissues adjacent the brain cavity.

0009In certain embodiments the system can include at least one regulator connected to the at least one canister and to the delivery tube. Adiabatic cooling of the gas as it enters the delivery tube from the regulator(s) cools the gas to a first temperature of between about 0° and 20° Celsius, and the gas exits the nasal tubes at a second temperature not less than the first temperature and between about 0° and 20° Celsius. The supply of breathable gas is sufficient in flow, temperature and duration to cool at least a portion of the brain by about 1 to 5 Celsius degrees. The supply can be provided by multiple canisters of compressed gas, with the delivery tube is adapted to easily accept flow from multiple canisters. The delivery tube may be connected to a stopcock, with the stopcock connected to the multiple canisters of compressed gas and operable to switch flow into the delivery tube between or among the multiple canisters. The configured condition of the delivery tube may include a layer of insulation incorporated in or on the delivery tube.

0010Also disclosed is a cooling system for applying localized hypothermic treatment, including a heat-transfer medium consisting essentially of a breathable gas supplied in a canister at a pressure greater than atmospheric pressure. The gas does not have in it or propel any liquids. A delivery tube is connected to the canister, and is configured so that the gas can travel along it without a significant change in temperature of the gas along the delivery tube's length. A pair of insertion tubes is connected to the delivery tube and are sized and configured so that respective distal ends of each insertion tube are in the choanae of the patient when the insertion tubes are fully inserted into the patient. The canister may be of a hand-portable size and weight, so that the system is carryable to a patient by an emergency responder. The configured condition of the delivery tube can include forming the delivery tube entirely of an insulation, such as foam insulation. The insertion tubes may each have a single outlet at their respective distal ends so that the gas exits the tubes in one direction.

0011The disclosure includes a compressed gas source (e.g. O₂, N₂) that may be attached to a regulator (either integrally or via high pressure tubing), with the output tubing from the regulator extending to a mask that is placed over the patient's mouth and nose. The delivery tube extends into the mask and diverges as a pair of smaller tubes that are inserted into the nasal cavity to deliver cold gas directly to the front of the sinus region. The nasal cavity tubes are of a longer length than standard nasal tubes for oxygen delivery so that they bypass or open beyond the anterior turbinate area of the nose, in which the greatest transfer of heat from the nasal mucosa to the incoming airflow has been shown to occur, thereby helping to better preserve the temperature of the cold gas being introduced. The nasal tubes are shorter than spray tubes in systems used to deliver volatile chemicals into the nose as spray via side ports, which spray tubes extend all the way to the back of the sinus region, so that contact with the sinus is maximized.

0012Systems for therapeutic cooling as disclosed herein and indicated above can thus include a mask having a strap and a hole, with the mask adapted to cover at least the patient's nose (and perhaps eyes, mouth and/or other parts of the face or head) and to be held to the patient's head by the strap. When the mask rests against the patient's face a space between at least a portion of the patient's face and the mask exists. A source of coolant, e.g. solely or essentially compressed breathable gas, and a flow path from that source through the mask's hole of said mask, can be provided. A regulator may be in the flow path between the coolant source and the hole, and a delivery tube having a lumen defines at least part of the flow path for conducting the coolant toward the mask. At least one sensor may be connected to one or more of the delivery tube, regulator and mask, and a readout is communicatively connected to the sensor(s) to provide information concerning the coolant. The coolant is cooled adiabatically after release from the source.

0013The source is a canister of compressed breathable gas in particular embodiments, with the canister being portable by hand or a stand-alone tank as examples. Insertion tubes may be connected to the delivery tube, for example with each extending to a respective free end having an opening and/or with each sized and configured to be inserted into respective nares of a patient's nose so that said free ends are positioned in the airway beyond the anterior turbinate area of the patient's nose. In such cases, the gas passes the mucosa and conchae of the nose before exiting the insertion tubes. At least one of the delivery tube or insertion tubes extend through the mask's hole so that the mask rests against the patient's face when at least one insertion tube is inserted into the patient's nose. Some embodiments include a configured condition of the delivery tube in which a length of the delivery tube is about one foot or less. Other exemplary configured conditions of the delivery tube include forming it of foam insulation, and/or of forming it of an internal plastic lumen with an outer layer of foam insulation. The source can include two compressed gas canisters. In such cases, the system may also include one or both of a Y-shaped connector connected to the delivery tube and to each of the canisters, and a two-way stopcock connected to each of the canisters and to the delivery tube.

0014The regulator is fixed in particular embodiments to the mask so that an output of the regulator communicates with the mask's hole, with adiabatically-cooled gas from the regulator entering the mask. A high-pressure tube from said source to said regulator may be used. In various mask embodiments, the mask can cover the eyes and/or mouth of a patient as well as the nose, and may be a full-face mask. The readout can be fixed to the mask while the mask permits observation of the patient's eyes when fitted to the patient, so that the patient's eyes and the readout are both within an observer's field of vision when the mask is fitted to the patient.

0015A system for cooling the brain with compressed gas can also be characterized as having a supply of a compressed breathable gas for thermal transfer with tissues in a patient's head, provided in at least one canister initially at a first pressure greater than atmospheric pressure, and a mask for fitting over a patient's face to cover at least the patient's nose and eyes, the mask having a regulator fitted to it. A high-pressure delivery tube connects the canister(s) with the regulator, and the delivery tube is configured such that gas traveling along it remains at approximately the same temperature. The gas is cooled adiabatically by passage through the regulator to a first temperature below room temperature, and it flows into the mask at approximately the first temperature to cool tissues adjacent the brain cavity. In some embodiments, a set of first and second nasal tubes each for insertion into a respective nostril of a patient are provided, such tubes each having a respective distal end with a respective hole, and each being sized and configured so that when they are fully inserted into the patient, the respective distal ends are positioned in one or more of the patient's choanae. The first temperature, for example, is between 0 and 20 degrees Celsius. The supply of breathable gas may be sufficient in flow, temperature and duration to cool at least a portion of the brain by about 1 to 5 Celsius degrees. In particular embodiments, the supply is provided by multiple canisters of compressed gas, with the delivery tube adapted to easily accept flow from multiple canisters. For example, the delivery tube may be connected to a stopcock, which is connected to multiple canisters of compressed gas, with the stopcock operable to switch flow into the delivery tube between or among the canisters. As above, a configured condition of the delivery tube can include a layer of insulation incorporated in or on the delivery tube.

0016A cooling system for applying localized hypothermic treatment may include a heat-transfer medium consisting essentially of a breathable gas, with the gas supplied in at least one canister at a pressure greater than atmospheric pressure. A delivery tube is connected to the canister(s) and is configured so that the gas can travel along the delivery tube without significant change in temperature of the gas along the length of the delivery tube. A mask has a regulator that is connected to the delivery tube so that the regulator's output flows into the mask, and a readout display that shows information related to the operation of the system, which information may come from one or more sensors (e.g. flow-rate or temperature sensors) in the mask, delivery tube, or other parts of the system. A stopcock is connected to the delivery tube and is operable to change flow into the delivery tube from a first canister to a second canister. As noted above, embodiments can include a pair of insertion tubes connected to the delivery tube and sized and configured so that respective distal ends of each of them are in the patient's choanae when the insertion tubes are fully inserted into the patient. The canister(s) may be of a hand-portable size and weight, so that the system is carryable to a patient by an emergency responder. The configured condition of the delivery tube may include forming it entirely of a foam insulation, and if used, insertion tubes may each have a single outlet at their respective distal ends so that gas exits the tubes in one direction.

0017Tubing length for current respiratory oxygen delivery systems is selected to maximize warming of the oxygen as it is released from the source tank and flows to the nasal tubing. In the present system, the length of that tubing is shortened as much as possible, in one embodiment about a foot in length, to maintain the low temperature or negative thermal energy of the gas. To further limit the effect of ambient warming of the gas flow or warming from direct contact with the patient, the delivery tubing and/or nasal tubing may be clad with insulation such as foam or another suitable material that limits heat transfer. With the delivery tubing shortened to limit heat transfer and the nasal tubing lengthened to limit warming of the gas by the nasal cavity, the lowest available temperature of gas is delivered to the sinus for maximum therapeutic benefit. The present system may be configured in a unit as an emergency kit that can be used by an EMT or kept at a business or other site, such as mounted to a wall alongside an AED (automated external defibrillator). The size of the medical gas canister or cylinder varies according to the intended use of the device, e.g. whether it is to treat a stroke victim prior to arrival of emergency help (e.g. about a ten or fifteen minute supply), or for during transport to a hospital until other measures can be taken. Of course, gas canisters or bottles can be exchanged as they are depleted.

0018These and other features are described in detail below, disclosing a less complicated, more elegant and more portable or ambulatory solution for providing more direct therapeutic cooling to particular tissues, e.g. the brain to combat ischemia due to stroke, cardiac arrest or other causes, swelling due to trauma, or other damage. Handling of volatile chemicals, provision of sophisticated mixing or monitoring apparatus, incorporation of electrical or other external cooling or refrigeration items, insertion of balloons or other airway-blocking structure, and other complications are unnecessary, and embodiments of the present disclosure are easily portable and accessible when and where needed.

BRIEF DESCRIPTION OF THE DRAWINGS

0019<figref idref="DRAWINGS">FIG. 1</figref> is a representation of an embodiment of a system according to the present disclosure.

0020<figref idref="DRAWINGS">FIG. 2</figref> is an embodiment of a gas canister of the embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0021<figref idref="DRAWINGS">FIG. 3A</figref> is a perspective view of an embodiment of mask structure in the embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0022<figref idref="DRAWINGS">FIG. 3B</figref> is a perspective view of an embodiment of another type of mask structure useful in the embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0023<figref idref="DRAWINGS">FIG. 4</figref> is an embodiment of a delivery tube in the embodiment of <figref idref="DRAWINGS">FIG. 1</figref>.

0024<figref idref="DRAWINGS">FIG. 5</figref> is an embodiment of a delivery tube as in <figref idref="DRAWINGS">FIGS. 1 and 4</figref>, with additional structure.

0025<figref idref="DRAWINGS">FIG. 6</figref> is a schematic representation of a portion of the embodiment shown in <figref idref="DRAWINGS">FIG. 1</figref> in cross section and applied to a patient.

0026<figref idref="DRAWINGS">FIG. 7A</figref> is a representation of a portion of a system as in <figref idref="DRAWINGS">FIG. 1</figref> with an embodiment of a connection between gas canisters and a delivery tube.

0027<figref idref="DRAWINGS">FIG. 7B</figref> is a representation of a portion of a system as in <figref idref="DRAWINGS">FIG. 1</figref> with another embodiment of a connection between gas canisters and a delivery tube.

0028<figref idref="DRAWINGS">FIG. 8</figref> is a cross-sectional representation of a tube or portion thereof indicated in <figref idref="DRAWINGS">FIG. 1</figref> in a particular embodiment.

0029<figref idref="DRAWINGS">FIG. 9</figref> is a schematic representation of a portion of the embodiment shown in <figref idref="DRAWINGS">FIG. 3B</figref> in cross section and applied to a patient.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

0030For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claims is thereby intended, and alterations and modifications in the illustrated device, and further applications of the principles of the disclosure as illustrated therein are herein contemplated as would normally occur to one skilled in the art to which the disclosure relates.

0031Referring generally to the drawings, there is shown an embodiment of a system <b>20</b> for cooling particular tissues in the human or animal body. Throughout the following discussion, the cooling of the brain as part of a therapy for treating brain ischemia is noted as an example of a treatment method and of the use of system <b>20</b>. It will be understood that cooling of other particular parts of the body can also be performed using system <b>20</b>.

0032In the illustrated embodiment, system <b>20</b> includes a source of compressed gas, such as a canister <b>22</b>, a delivery tube <b>24</b> connected to canister <b>22</b>, and a pair of insertion tubes <b>26</b>, <b>28</b> connected to delivery tube <b>24</b>. In general, as discussed further below, gas flows in a flow path from canister <b>22</b> or other source through delivery tube <b>24</b> (and insertion tubes <b>26</b>, <b>28</b>, if provided) and to the patient.

0033Canister <b>22</b> in the illustrated embodiment is a standard container for holding a gas in a pressurized state. Accordingly, canister <b>22</b> has a valve or regulator <b>32</b> and an opening <b>34</b> for allowing gas to be released from canister <b>22</b> at one or more flow rates or pressure levels. For example, item <b>32</b> may be a regulator designed to step the pressure in canister <b>22</b> down to a lower pressure that is above atmospheric pressure. Standard tanks, cylinders or other canisters commonly contain gases pressurized to about 2000-6000 psi, and regulator <b>32</b> may step that pressure down to a level above atmospheric pressure (14.7 psi or 760 mmHg) that will allow steady, non-injurious flow of gas into and through delivery tube <b>24</b>. In some embodiments, valve or regulator <b>32</b> may be connected to canister <b>22</b> or other gas source via high-pressure tubing or conduit, rather than being fixed to or integrally with canister <b>22</b>, e.g. to a mask as noted further below.

0034Canister <b>22</b> may be of any size appropriate to delivering gas in a therapeutic setting. In particular embodiments, canister <b>22</b> is a portable cylinder or bottle containing an amount of gas sufficient for a short term (about ten to fifteen minutes) supply at the flow rate(s) or pressure level(s) permitted by valve or regulator <b>32</b>. As one example, canister <b>22</b> may be a standard C, D, or E cylinder having an appropriate CGA (Compressed Gas Association)-standard connection. In other embodiments, canister <b>22</b> may be a tank of approximately the size of a portable breathing tank for firefighters or scuba-divers, or of approximately the size of stand-alone tanks found in laboratories. In the latter case, it will be understood that such tanks are not portable by hand, but may be stationed at an appropriate location in a building (e.g. a hospital) or a vehicle (e.g. an ambulance).

0035The gas within canister <b>22</b> is a breathable gas, i.e. one compatible with administration into a patient's airway and sinus passages, so that as administered it is non-toxic and provides little or no chemical or biological damage to tissues along the respiratory system or other parts of the body. In particular embodiments, the gas is air, a molecular gas such as oxygen (O₂) or nitrogen (N₂), an enriched air nitrox, heliox, or combinations of one or more of those gases with each other or with other gases. In certain embodiments, the gas within canister <b>22</b> is substantially pure, having no significant percentages of other undesired gases, and no biologically active ingredients. The gas within canister <b>22</b> is at a pressure that depends on the fullness of canister <b>22</b> but is significantly greater than atmospheric pressure, and as already noted, in some embodiments gas within a substantially full canister <b>22</b> is at a pressure of about 2000-6000 psi, or at pressures common to medical-use gas canisters. Accordingly, in one embodiment canister <b>22</b> is a medical-grade or medical-use canister or tank filled with oxygen and which has a valve or regulator <b>32</b> fixed or otherwise connected to it for stepping the pressure of the oxygen down to a pressure greater than atmospheric pressure.

0036Delivery tube <b>24</b> is connected to canister <b>22</b> (e.g. at a valve or at regulator <b>32</b>, if provided) and includes a central lumen <b>36</b> in this embodiment for transfer of gas from canister <b>22</b>. Delivery tube <b>24</b> is flexible and relatively lightweight in the illustrated embodiment, so as to permit easy movement and arrangement of tube <b>24</b> according to the needs of the patient and user of system <b>20</b>. In particular embodiments, delivery tube <b>24</b> is or includes a tube of polyvinyl chloride (PVC) or similar material capable of handling continuous gas flow without rupture or significant leakage. Delivery tube <b>24</b> also has good insulating properties in certain embodiments, limiting heat transfer from the environment to gas within lumen <b>36</b>. Accordingly, if tube <b>24</b> is of only one layer forming lumen <b>36</b>, then the material should have good resistance to heat conductance and/or the thickness of the layer should minimize heat transfer between lumen <b>36</b> and the environment outside of tube <b>24</b>. In particular, the tube material should prevent heat from being transferred from outside tube <b>24</b> into lumen <b>36</b>. For example, tube <b>24</b> may be of a material such that the thickness of the material necessary to keep heat transfer at a minimum will not form a tube too large to be inserted into a patient's nose.

0037In specific embodiments, insulation may be a part of or incorporated into tube <b>24</b> (and/or tubes <b>26</b>, <b>28</b>, discussed further below). For example, tube <b>24</b> may be formed entirely of a foam insulation, as by extrusion. Further, more than one layer may be included in tube <b>24</b> to increase its insulating properties, or one or more layers of foam or other insulation <b>38</b> may be provided around or at least partially mixed with tube <b>24</b> along some or all of its length. For example, tube <b>24</b> can be made through a coextrusion of a thin layer <b>39</b> of PVC or similar material (forming an internal lumen L) with an external layer of foam insulation <b>38</b>. Such a tube has gas-nonpermeability qualities of PVC internally while being softer and more comfortable or less-potentially injurious to the patient and insulated externally. Such embodiments of tube <b>24</b> prevent significant warming of gas from canister <b>22</b> as it travels through lumen <b>36</b> in delivery tube <b>24</b>.

0038Delivery tube <b>24</b> extends to or through a mask <b>40</b>, in particular embodiments, that is adapted for placement over at least the nose and perhaps other parts of the face of a patient (e.g. eyes and/or mouth) for convenience and security in holding tube <b>24</b> and administering cooling to the patient. In the illustrated embodiments, mask <b>40</b> has a body <b>42</b> with a hole <b>44</b> in the front through which a portion of delivery tube <b>24</b> extends, and a strap <b>46</b> attached to opposing sides of body <b>42</b> for holding mask <b>40</b> to the face of the patient. Hole <b>44</b> is of approximately the same size as the outer diameter of delivery tube <b>24</b>. A washer, valve, O-ring or other sealing or holding member (not shown) may be provided in or adjacent to hole <b>44</b> so as to form at least a minimal seal between mask <b>40</b> and delivery tube <b>24</b>, and/or to keep tube <b>24</b> from moving or moving significantly with respect to mask <b>40</b>. Mask <b>40</b>, <b>40</b>′ may be of a plastic, substantially gas-impermeable material, and may be such as is used over a patient's nose and mouth to provide oxygen to comatose or less-responsive patients (e.g. <figref idref="DRAWINGS">FIG. 3A</figref>), or other types of masks such as those covering the eyes and nose (e.g. <figref idref="DRAWINGS">FIG. 3B</figref>). Each provides a space between the mask and the face of the patient when the mask is fitted to the patient. As previously indicated, mask <b>40</b> is intended to cover at least a portion of the face to enable cooling gas to be administered to the patient.

0039In the former case (<figref idref="DRAWINGS">FIG. 3A</figref>), body <b>42</b> is generally circular or oval in shape to cover at least the nose and mouth of the patient. Hole <b>44</b> is in the middle or upper area of mask <b>40</b> to be generally adjacent the patient's nose when mask <b>40</b> is fitted. Delivery tube <b>24</b> diverges inside mask <b>40</b> into insertion tubes <b>26</b>, <b>28</b>. Insertion tubes <b>26</b>, <b>28</b> are parts of delivery tube <b>24</b> that branch off for insertion into the body, and each tube <b>26</b>, <b>28</b> has its own lumen <b>50</b>, <b>52</b>. Lumens <b>50</b>, <b>52</b> are centrally located within respective tubes <b>26</b>, <b>28</b> and communicate with or continue on from lumen <b>36</b> of tube <b>24</b> in this embodiment. In other embodiments, insertion tubes <b>26</b>, <b>28</b> may be made separately from delivery tube <b>24</b>, as by joining tubes <b>26</b>, <b>28</b> in a base or stem to form a generally Y-shaped structure, which is attached (e.g. welded or otherwise sealed) to the end of delivery tube <b>24</b> within mask <b>40</b>.

0040In the latter case, mask <b>40</b>′ may be generally in the form of a scuba-type mask (<figref idref="DRAWINGS">FIG. 3B</figref>). Mask <b>40</b>′ includes a body <b>42</b>′ with a hole <b>44</b>′, and a strap <b>46</b>′ for passing around or over the patient's head to maintain mask <b>40</b>′ against the patient's face. Body <b>42</b>′ is sized and configured to cover at least the patient's nose and eyes. The illustrated embodiment of mask <b>40</b>′ includes a sealing member <b>43</b>′ around the portion of mask <b>40</b>′ that contacts the face, and sealing member <b>43</b>′ may be in the form of a skirt or compressible rubber, latex or plastic edge. Sealing member <b>43</b>′, under the force provided by strap <b>46</b>′ in holding mask <b>40</b>′ to the face, provides an fluid-tight (e.g. airtight) seal between body <b>42</b>′ and the patient's face. Body <b>42</b>′ may be closed or unitary, i.e. one-piece, or it can have an outer frame <b>42</b>′<i>a </i>and an inner portion or insert <b>42</b>′<i>b</i>. In a particular embodiment of the latter case, inner portion <b>42</b>′<i>b </i>is generally in front of the patient's eyes when mask <b>40</b>′ is fitted to the patient. One or more vents (not shown) may be included in body <b>42</b>′ (including either or both of frame <b>42</b>′<i>a </i>and inner member <b>42</b>′<i>b</i>, if present) to permit venting of the space inside mask <b>40</b>′, should it be necessary for any reason to remove the cooled gas from inside mask <b>40</b>′ or to otherwise affect or alter the environment within mask <b>40</b>′. Inner portion <b>42</b>′<i>b </i>has a fluid-tight or airtight seal with frame <b>42</b>′<i>a </i>and may be transparent to permit a physician, medical technician or other professional to observe the patient's eyes and facial tissue during treatment. While mask <b>40</b>′ is illustrated in an embodiment that covers the eyes and nose of a patient, it will be understood that other embodiments may cover eyes, nose and mouth, or be a full-face mask.

0041Hole <b>44</b>′ is in a relatively central location in mask <b>40</b>′, and may act as or include an inlet or port for gas from canister <b>22</b> or other gas source. As indicated above, a regulator <b>32</b> may be located away from a canister <b>22</b> but connected to it via high-pressure tubing or conduit, and as shown in <figref idref="DRAWINGS">FIG. 3B</figref> regulator <b>32</b> is connected or fixed to mask <b>40</b>′ so that the outlet or output of regulator <b>32</b> communicates with hole <b>44</b>′. In other embodiments, a short tube (not shown) may connect the outlet of regulator <b>32</b> with hole <b>44</b>′. The flow path for gas extends from the source (e.g. canister <b>22</b>) through tube <b>24</b> and regulator <b>32</b> to mask <b>40</b>′. High-pressure gas flows to and through regulator <b>32</b>, being stepped down in pressure (and reduced in temperature) and directly flowing into the interior of mask <b>40</b>′. In such an embodiment, in which mask <b>40</b>′ is provided with an attached regulator <b>32</b> and tube <b>24</b> is formed of high-pressure tubing, mask <b>40</b>′ is easily disconnected from an empty gas source (e.g. a canister) and reconnected to a full canister or other source.

0042Mask <b>40</b>′ in the illustrated embodiment does not include insertion tubes <b>26</b>, <b>28</b>, although it will be understood that other embodiments could include such tubes arranged and utilized as described herein. Without insertion tubes <b>26</b>, <b>28</b> to carry gas into the nose, the internal space of mask <b>40</b>′ (inside of mask <b>40</b>′, between itself and the patient's face) contains cooling gas. Some of the gas is inhaled through the nose, while some remains in the space over the patient's eyes, cheeks, nose and perhaps other facial parts enclosed by mask <b>40</b>′. Inhaled gas passes through the nose to the choanae to provide cooling. In this embodiment, the temperature of the gas flowing into mask <b>40</b>′ can be somewhat cooler than may be provided for mask <b>40</b>, because there will be some warming of the gas as it passes through the tissues of the nose. Further, the gas inside the mask provides cooling to and via softer tissues, such as those of the eye. As with the soft tissues within the nasal airway, cooling of the soft eye tissues can be passed to the brain and its vascular system, as no hard bone tissue or similar insulator interferes. Blood in the eye tissue drains by way of the ophthalmic veins through the sinuses, and thus cooled venous blood from the eye tissue drains adjacent the sinuses and brain tissue.

0043In a particular embodiment, a system <b>20</b> can be set up to provide a positive pressure of breathable gas for the patient. For example, regulator <b>32</b> may be set to outlet gas at a pressure sufficiently above atmospheric pressure so as to create a positive pressure, so that gas is always available when the patient inhales, and so that exhalation is generally or entirely channeled through the patient's mouth. Pressures above atmospheric pressure, such as 1.1 atmospheres (atm), 1.5 atm, 2.0 atm, or other pressures between 1.1 atm and 2.0 atm are believed to be advantageous in administering therapy as disclosed herein. As a particular example using mask <b>40</b>′, system <b>20</b> is set up to provide a positive pressure of about 1.5 atm within mask <b>40</b>′. The positive pressure is accessible to the nose of the patient, while his or her mouth is adjacent or within atmospheric pressure (e.g. 1.0 atm). When the patient inhales, the positive pressure at his or her nose ensures that a substantial proportion (if not substantially all) of the inhaled gas comes through the nose and nasopharynx, because of the force of the positive pressure, and is thus the cooling breathable gas from system <b>20</b> rather than room temperature air. Further, if pressure is maintained, there is gas available for inhalation every time the patient breathes in. Every inhalation thus provides additional cooling gas to the nasopharynx and on to the patient's lungs. When the patient exhales, the path of least resistance to the exhalation is the mouth, where the pressure is significantly less than the positive pressure in mask <b>40</b>′ and/or in the patient's nasal airway. Consequently, gas that has been warmed in traveling to and from the patient's lungs is at least largely or completely kept from the nasopharynx and associated soft tissues. Such positive pressure can thus create a flow or circulation, from the space inside mask <b>40</b>′ through the nose and nasopharynx to the lungs, and from the lungs out through the mouth, with little or no exhalation into mask <b>40</b>′. A consistent supply of cooling gas is provided to appropriate soft tissues at every inhalation, and the approach of warmer gases to those soft tissues is reduced or eliminated.

0044Mask <b>40</b>, <b>40</b>′ may be of a plastic, substantially gas-impermeable material, and may be such as is used to provide oxygen to comatose or less-responsive patients, or the like. In other embodiments, mask <b>40</b>, <b>40</b>′ may be of a more gas-permeable material or provided with vents or other openings so as to limit or prevent damage to the patient's facial skin during use over long periods. In embodiments in which mask <b>40</b> is not present, delivery tube <b>24</b> and/or nasal tubes <b>26</b>, <b>28</b> may be held to the patient by a surgical or adhesive tape, clamp or other structure to minimize or prevent movement of tubes <b>24</b>, <b>26</b>, <b>28</b> with respect to the patient as the patient is moved or treated.

0045Insertion tubes <b>26</b>, <b>28</b> are nasal tubes in the illustrated embodiment, each of a diameter adapted for insertion into a respective nostril (nare), and each of a length so that when properly inserted they extend beyond the anterior turbinate area (conchae) of the nose, bypassing the area in the nose that transfers the greatest amount of heat to inhaled air. Tubes <b>26</b> and <b>28</b> have their respective ends and outlets <b>54</b>, <b>56</b> beyond the conchae, and in a particular embodiment between the conchae and the front of the sinus area (i.e. the rear portion of the nasal cavity), with the sphenoidal bone and associated cartilage and other tissue in that area. Tubes <b>26</b>, <b>28</b> may (but need not) reach the back of the sinus region, as may be required or important for tubes that spray volatile coolants into or around the sinus cavities or that use balloons to hold coolant or block the airway.

0046Insertion tubes <b>26</b>, <b>28</b> each have a single distal opening <b>54</b>, <b>56</b> in the illustrated embodiment, in order to focus gas on a particular area proximate to the brain as indicated above. The single distal opening allows a consistent flow of gas to the desired area so as to continuously replace gas that has received heat (or transferred cooling) with new cooling gas. In other embodiments, additional openings may be provided, such as additional opening(s) at the distal end of tubes <b>26</b> and/or <b>28</b>, or one or more openings in the side(s) of tubes <b>26</b> and/or <b>28</b>. Additional or numerous openings in tubes <b>26</b> and/or <b>28</b>, e.g. in the sides, can be provided. However, a single or fewer openings are effective in directing gas where it is needed, e.g. against the sphenoidal bone to focus cooling on the brain and vascular structures behind it, and further openings can spread gas toward tissues for which cooling is not desired or in directions that are less effective. Directed flow further obviates a need to artificially maintain the gas in a particular location, and assists the patient to inhale the provided gas naturally.

0047It should be noted that in therapy situations in which gas is administered, for example in which oxygen is provided to patients to increase oxygen richness or for other breathing assistance, gas is delivered either at a relatively high temperature (e.g. room temperature) as it enters tube(s) to the user, or are delivered through several feet or longer lengths of non-insulated tubing to allow ambient temperature to warm the gas to approximately room temperature before it gets to the patient. Further, tubes or masks providing the gas are designed to terminate at or just inside the nostrils' openings for user comfort and so that heat and moisture can be transferred to the incoming gas via the mucosa. Having the gas at approximately room temperature is important for the patient's comfort and for limiting effects of cold gas on tracheal, bronchial or lung tissue. In contrast, system <b>20</b> is designed to make sure the gas provided to the patient remains as cold as possible consistent with non-injurious cooling of tissue. Delivery tube <b>24</b> is accordingly maintained as short as possible, in some embodiments about one foot or less, and having insulating characteristics.

0048System <b>20</b> in a particular embodiment is a portable or ambulatory system, such as a kit (or part of a kit) that can be carried and used by an emergency medical technician, physician or other first-responder to an apparent health emergency. Such a kit may be kept on site at schools, businesses, public buildings, and the like in the same way as automated external defibrillators (AEDs) have been placed, e.g. mounted to a wall or positioned in a security or first aid area. In that configuration, system <b>20</b> may be used to treat a patient (e.g. victim of stroke or cardiac arrest) prior to the arrival of emergency help, and/or during transport to a hospital for additional treatment measures. For temporary help situations, canister <b>22</b> may be sized to provide a relatively short-term supply of gas, such as a size C or D gas cylinder or a cylinder of the size generally carried by firefighters or scuba divers. A somewhat larger canister <b>22</b> (e.g. a tank) or other source of compressed gas, with a longer-lasting supply, can be available in an ambulance or hospital. In either case, new gas canisters <b>22</b> can be provided to exchange with spent canisters <b>22</b> as treatment continues. It will be understood that the size and configuration of system <b>20</b> discussed above, in particular the short length of delivery tube <b>24</b> and portability of the small gas canisters, will be particularly useful for an ambulatory emergency system <b>20</b>.

0049For ease in exchanging one canister <b>22</b> (e.g. an empty or smaller capacity canister) for another canister <b>22</b> (e.g. a full or larger capacity canister or tank), particular types of connections can be placed at a proximal end of delivery tube <b>24</b>. As one example, a connection <b>60</b> on delivery tube <b>24</b> may be a standard connection for canisters holding a particular type of gas, e.g. a CGA connection for oxygen tanks. Such a connection reduces or eliminates the chance of connecting delivery tube <b>24</b> to an incorrect gas source, to an IV tube, or other potential hazard.

0050Alternatively or additionally, a Y-connection <b>64</b> or a stopcock <b>66</b> may be provided in delivery tube <b>24</b>. If Y-connection <b>64</b> is used, separate canisters <b>22</b> (or their respective regulators or valves) can be connected to respective branches of connection <b>64</b>. One canister can be opened for gas flow while the other remains closed. When that canister approaches or becomes empty, the second can be opened to continue the flow, while the empty canister is removed and replaced with a full canister. In such embodiments, a one-way valve (not shown) may be placed in each branch of Y-connection <b>64</b> so that gas does not escape through a branch disengaged from an empty canister.

0051Stopcock <b>66</b> is a two-way stopcock with two separate inlets connected to respective canisters <b>22</b>, and an outlet connected to delivery tube <b>24</b>. In such embodiments, both canisters <b>22</b> can be open. When stopcock <b>66</b> is in a position allowing flow from one of the canisters, flow from the other is blocked. As the canister approaches or reaches empty, stopcock can be turned to allow flow from the other canister, while the empty canister is removed and replaced. Y-connection <b>64</b> and/or stopcock <b>66</b> permit flow to continue through delivery tube <b>24</b> to the patient without significant interruption while empty canisters are replaced.

0052As noted above, delivery tube <b>24</b> can be constructed to be assembled to canister <b>22</b> prior to use of system <b>20</b>, and that a connection on delivery tube <b>24</b> that allows easy attachment and detachment with canister <b>22</b> can be provided. In such embodiments, as a canister <b>22</b> approaches empty or otherwise cannot provide further gas cooled by a pressure drop, delivery tube <b>24</b> can be quickly and easily disconnected from that canister <b>22</b> and reattached to another canister <b>22</b>, or flow can be obtained from a second canister via Y-connection <b>64</b> or stopcock <b>66</b>. Thus, in an example in which a patient is being treated on-site, when cooling from a first canister <b>22</b> is exhausted, a second canister <b>22</b> may be attached. When an ambulance arrives, the delivery tube <b>24</b> may be disconnected from the on-site system <b>20</b> and connected to a system <b>20</b> on board the ambulance. Likewise, when the ambulance arrives at a hospital, if cooling is to be continued at the hospital delivery tube <b>24</b> may be disconnected from the ambulance's system <b>20</b> and connected to a system <b>20</b> in an operating room or other treatment area. It will be seen that such connectivity of delivery tube <b>24</b> may be provided at the end where delivery tube connects to canister <b>22</b> and/or valve of regulator <b>32</b>, at a connection in the middle of delivery tube <b>24</b>, or at the end of delivery tube that connects with mask <b>40</b> and/or insertion tubes <b>26</b>, <b>28</b>.

0053It is also contemplated to include attachments to mask <b>40</b>, <b>40</b>′ that may be useful in treating all patients, or those who are comatose, non-responsive (e.g. in cardiac and/or respiratory arrest) or have other difficulties. For example, <figref idref="DRAWINGS">FIG. 9</figref> includes a representation of an embodiment of mask <b>40</b>′ that includes structure for maintaining an open mouth, including a tube <b>80</b> for insertion in to the mouth and along the tongue, a bite block <b>82</b> (which may be a part of or attached to tube <b>80</b>), and lip or mouth coverings <b>84</b> (which also may be a part of or attached to bite block <b>82</b> and/or tube <b>80</b>). Tube <b>80</b> generally maintains the oral cavity open for exhalation, and may also be used for insertion or attachment of equipment or instruments, and/or to facilitate artificial breathing during application of CPR, as the medical professional may desire. Bite block <b>82</b> maintains a spacing of the patient's teeth, both to keep the mouth open and to protect patient and medical professional from bite injuries. Coverings <b>84</b> generally cover the lips and nearby tissues, so as to shield the medical professional from bodily fluids from the patient. In addition to providing cooling gas via mask <b>40</b>, <b>40</b>′, such structures provided as a part of or attached to mask <b>40</b>, <b>40</b>′ can be fitted to the patient for safety and to maintain an open passage through the mouth. As noted above, maintaining that passage can provide for exhalation through the mouth via tube <b>80</b>, and can thus provide a more efficient cooling for the patient. The embodiment of mask <b>40</b>′ includes an insertion tube <b>26</b> as described above, so that it will be seen that embodiments of mask <b>40</b>′ may include tubes <b>26</b> and/or <b>28</b>, and embodiments of mask <b>40</b> may be provided without them.

0054In use, system <b>20</b> is applied to a patient, e.g. one diagnosed as having a traumatic head or brain injury, stroke, cardiac arrest, shock or other condition causing or leading to swelling or ischemia in the brain. In the illustrated embodiment, system <b>20</b> is provided with canister <b>22</b> already connected to or integral with delivery tube <b>24</b>, and nasal tubes <b>26</b>, <b>28</b> and mask <b>40</b> connected to delivery tube <b>24</b> as discussed above, prior to use. That is, system <b>20</b> is provided in a ready-to-use state. It will be understood that system <b>20</b> could also be provided with some assembly needed, such as assembly of delivery tube <b>24</b> to canister <b>22</b>, or of mask <b>40</b> and/or nasal tubes to delivery tube <b>24</b>. If assembly is needed, quick and secure connections as indicated above are preferred. Assembly (particularly of delivery tube <b>24</b> to canister <b>22</b>) may be needed if gas canister <b>22</b> should be stored separately or remain unconnected to a conduit for safety reasons. Additionally, as noted above quick-connect or other easy connection(s) may be provided in one or both ends and/or the middle of delivery tube <b>24</b> so as to permit disconnection and reconnection of delivery tube <b>24</b> in connecting new gas sources to system <b>20</b>.

0055Insertion tubes <b>26</b>, <b>28</b> are placed through the respective nostrils of the patient as mask <b>40</b> is moved toward the patient's nose and mouth. Tubes <b>26</b>, <b>28</b> are inserted further into the nasal cavity as mask <b>40</b> approaches the nose and mouth, so that the ends of tubes <b>26</b>, <b>28</b> extend beyond the air-warming anterior turbinate area of the nose, e.g. to the front of the patient's choanae or sinus area, when mask <b>40</b> is positioned over the patient's nose and mouth. Although insertion tubes <b>26</b>, <b>28</b> are intended to move through the nasal passage with little discomfort or resistance, one placing mask <b>40</b> and insertion tubes <b>26</b>, <b>28</b> may apply a medical lubricant to the nostrils and adjacent tissues and/or nasal tubes <b>26</b>, <b>28</b> if necessary. If lubricant is used, it should be assured that openings <b>54</b>, <b>56</b> in nasal tubes <b>26</b>, <b>28</b> are not obstructed. Strap <b>46</b> is placed around the patient's head to hold mask <b>40</b> against the patient's face and nasal tubes <b>26</b>, <b>28</b> in static position within the nose and their ends adjacent the sinuses.

0056Gas flow from canister <b>22</b> may be started prior to or after placement of tubes <b>26</b>, <b>28</b> within the patient, but starting flow after placement may make placement easier through having no resistance or force from the gas flow to contend with. When canister <b>22</b> is opened, e.g. by opening valve or regulator <b>32</b>, gas moves from canister <b>22</b> into delivery tube <b>24</b>. As the pressurized gas leaves canister <b>22</b> and enters delivery tube <b>24</b>, the drop in pressure provides a concomitant drop in temperature of the gas. The gas in delivery tube <b>24</b> is thus at a temperature substantially below room or ambient temperature and body temperature, and in particular embodiments is between 0° Celsius and 20° Celsius, such as around 0° Celsius. As discussed above, delivery tube <b>24</b> is configured to reduce or prevent substantial heat gain and preserve the negative thermal energy of the gas as it passes along tube <b>24</b>, by limiting the length of tube <b>24</b> to a minimum, for example one foot, and/or by insulating tube <b>24</b>. With the length of insertion tubes <b>26</b>, <b>28</b> lengthened as compared to oxygen therapy systems to limit warming of the gas by the nasal cavity, the gas is moved through delivery tube <b>24</b> and into and through insertion tubes <b>26</b>, <b>28</b> so that it remains cool. For example, the gas has a temperature not less than its temperature at the proximal end of delivery tube <b>24</b> (assuming no refrigeration along delivery tube <b>24</b>) as it exits tubes <b>26</b>, <b>28</b>, and is desirably at approximately the same temperature it had at the proximal end of delivery tube <b>24</b>. The exit temperature of the gas should be within 20 Celsius degrees of its temperature in the proximal end of delivery tube <b>24</b>, more desirably within 0 to 5 degrees of that initial temperature, so as to provide a low enough exit temperature to provide sufficient cooling to tissue. No external refrigeration, pumps or other equipment are needed in this embodiment to cool or maintain the low temperature of the gas or to propel it or ensure its composition, making this embodiment of system <b>20</b> non-electrical, although such additional equipment could be used in other embodiments. In the illustrated embodiment, the pressure drop from canister <b>22</b> to tube <b>24</b> provides a cooled gas, tubes <b>24</b>, <b>26</b> and <b>28</b> maintain the coolness or negative thermal energy level of the gas, and pressure from canister <b>22</b> moves the gas to the therapy site.

0057The low temperature gas is released through openings <b>54</b>, <b>56</b> in nasal tubes <b>26</b>, <b>28</b> into an area adjacent the brain, such as the choanae and/or nasopharynx, adjacent the sphenoid bone and sinus. The gas transfers its negative thermal energy to, or receives heat from, tissues proximate to the brain such as the sphenoid bone and sinus and adjacent tissues. A temperature gradient, between the gas and the tissues it contacts on one hand and brain tissue and blood vessels leading to the brain on the other, is created which reduces the temperature of blood flowing to and within the brain and brain tissue. Gas from canister <b>22</b> continues flowing as long as the administrator of treatment desires, funneling a continuing supply of cold gas to the base of the brain. The supply can be reduced when a desired brain temperature or a desired temperature reduction has been reached, so that the gas delivered to the choanae does not further reduce but merely maintains the temperature at the desired level. For example, a lowering of brain temperature of as much as 5 Celsius degrees, in particular embodiments of at least 3 to 4 Celsius degrees, may be sought to decrease or inhibit swelling of the brain tissue or reduce the onset or effects of ischemia. It has been found clinically that an improved outcome will be achieved if the temperature is lowered by at least 3 to 4 Celsius degrees. In other embodiments, a change of at least 1 to 2 Celsius degrees can provide benefit. Treatment with system <b>20</b> can cease when the treatment is no longer effective or necessary, as when it would interfere with surgery or other treatment, or when other treatments have concluded and a return to normal temperature and brain function is desired.

0058The above discussion identified particularly mask <b>40</b> in describing the use of system <b>20</b>. It will be understood that the use of embodiments such as mask <b>40</b>′ will be quite similar. To summarize, mask <b>40</b>′ may be provided pre-connected to delivery tube <b>24</b> and canister <b>22</b>, or may be connected at the time of use. Mask <b>40</b>′ is fitted on the patient's head with strap <b>46</b>′ as indicated above, without insertion of tube(s) into the patient's nose in embodiments of mask <b>40</b>′ that do not include such tubes. Flow of gas is begun, with the cooling gas at the desired temperature (and perhaps at a pressure above atmospheric pressure, as described herein) entering mask <b>40</b>′. Treatment occurs largely as noted previously, with gas cooling soft tissues (e.g. tissues within the nasal airway or eye tissue) adjacent the brain. When the desired cooling effect has been achieved, flow can be reduced to maintain the level of cooling, or stopped when cooling is no longer needed.

0059Although molecular oxygen and nitrogen have been suggested above as gases for use in system <b>20</b>, other gases palatable to humans may be used, such as a nitrogen/oxygen mix, heliox, or air. With such palatable gases and the arrangement of structures as noted above, the tissues and/or natural breathing processes of the patient will absorb or take in some or all of the gas for use in the body. Use of such gases obviates the need for system <b>20</b> to include an exhaust line or other structure for removing gas or other substances from the patient. Possibilities of hypoxia, toxic effect from liquids or other chemicals, and other negative effects are reduced or substantially eliminated, although good medical practice may dictate that the user of system <b>20</b> monitor the patient for abnormalities in body gases or chemistry.

0060For monitoring the patient, system <b>20</b> may include one or more monitors or sensors <b>70</b>. In the illustrated embodiment, sensor <b>70</b> is connected to the end of one of insertion tubes <b>26</b>, <b>28</b>, and in other embodiments it will be understood that sensor <b>70</b> may be placed in other appropriate locations, e.g. on or in tube <b>24</b> or a mask. Likewise, if more than one sensor <b>70</b> is provided, they may all be on one tube <b>26</b>, <b>28</b>, split between them, or otherwise positioned or attached with respect to the patient or system <b>20</b>. Sensor <b>70</b> may be directed to any of a number of factors or conditions associated with the use of system <b>20</b>. For example, sensor <b>70</b> may be a flow rate monitor or sensor in the flow of gas in tube <b>26</b> and/or <b>28</b>. As another example, sensor <b>70</b> may be a temperature sensor (such as an infrared sensor) along the outside of tube <b>26</b> and/or <b>28</b> and positioned against or within a mask, tissue or cavities (e.g. a sinus) to monitor temperature of the gas or tissues (e.g. those next to the brain or the brain cavity). Such a temperature sensor is along the outside of tube <b>26</b> and/or <b>28</b> (or through a second lumen if tube <b>26</b> and/or <b>28</b> is a dual-lumen tube), or within the space between a mask and the patient's face to obtain readings representative of gas or tissue temperature and to keep the temperature sensor out of gas flow if desired.

0061Sensor(s) <b>70</b> are connected via hard-wire, wireless or other connection to read-out(s) <b>72</b> accessible to the user. As the user or observer (e.g. physician or emergency technician) monitors such read-out(s) <b>72</b>, he or she can adjust system <b>20</b> as desired or necessary. For example, if sensor <b>70</b> is a flow rate sensor, it will give the user notification of decreasing flow indicative of a low gas supply in canister <b>22</b> or other flow-inhibiting or -reducing problem. If sensor <b>70</b> is a tissue-temperature sensor, it will give the user notification of temperature decreases or increases, and the user can adjust flow to maintain a desired cooled temperature or to change the temperature to a desired level. Based on flow and gas temperature, a target amount or duration of gas flow can be calculated so that at least an approximate period of use of system <b>20</b> to achieve a desired cooling effect is derived. The use of system <b>20</b> over that period should have the desired effect, and further monitoring of sensor(s) <b>70</b> can help the user maintain the effect.

0062One or more such readouts <b>72</b> may be provided to the user on a monitor screen, a hand-held screen, or other types of read-out display. A particular example is a display (e.g. screen, LCD, etc.) mounted on or fixed to mask <b>40</b>′. Such a display is fixed to a side surface or top surface of mask <b>40</b>′ in a location and position that does not impair the observation of the patient's eyes. That is, when the observer or user is focused on the patient's face, both the patient's eyes and readout(s) <b>72</b> are within the field of vision of the observer. Such placement is advantageous at least because it permits easy observation of both the patient's eyes and the display at the same time.

0063The description above described placement of insertion tubes <b>26</b>, <b>28</b> through the nostrils to a position at which the gas transferred through tubes <b>26</b>, <b>28</b> is at or about the temperature it has in delivery tube <b>24</b>. It will be understood that in other embodiments of system <b>20</b>, tube <b>26</b> and/or <b>28</b> can be inserted through the mouth, a tracheotomy or other opening and curved upward into or through the nasopharynx to deliver cool gas. In such embodiments, a single tube <b>26</b> might be provided, since only one body opening (rather than two nostrils) are available for placement. Further, the tube(s) <b>26</b> and/or <b>28</b> may be somewhat longer for placement through the mouth or other opening, and placement should be carefully made in light of the potential for activating the gag reflex.

0064Applying gas to the inside space of a mask, i.e. the airtight space between a mask and the patient's face provides cooling as well. The eyes and other external soft tissue of the head, just as with internal soft tissue, can be cooled in this way to reduce the temperature of adjacent brain tissue. Such a method can provide both internal cooling, via inhalation of cooling gas, and external cooling focused on the head's external soft tissues.

0065In such embodiments, the use of breathable gases provides both cooling and support for the patient's respiration. As already noted, existing respiration support systems ensure that administered gases are comfortable to the patient, e.g. so that they do not experience the “brain freeze” phenomenon sometimes felt when frozen foods or cold drinks are held in the mouth adjacent the palate. Accordingly, such systems will commonly use long tubes and/or electric or other heating elements associated with the gas-delivery tube in order to raise the gas temperature to a comfortable level, e.g. above room temperature. The present disclosure is intended to provide the opposite result of cooling to a degree that may cause discomfort to a patient, if the patient is conscious, so as to cool the brain tissue. Use of breathable gas is also beneficial in terms of supplying enrichment to the body during a cardiovascular event. During such events, blood flow is reduced, which consequently reduces the amount of oxygen reaching the cells. Providing a steady flow of breathable gas as in the present disclosure can increase the oxygen concentration in the blood. At least part of the negative effect of blood flow reduction can be compensated for by a higher oxygen concentration. The embodiment noted above that provides a positive pressure in a mask (e.g. mask <b>40</b>′) may be particularly useful in increasing oxygen concentration in the blood.

0066The above description also focused principally on the use of system <b>20</b> to cool the brain so as to minimize damage to the brain. It will be understood that system <b>20</b> can be applied to a patient in order to cool the brain and reduce its function in appropriate therapeutic situations other than minimizing damage from ischemia or swelling. Further, in situations in which another organ or body tissue or part should be cooled to minimize damage from ischemia or for other therapeutic reasons, system <b>20</b> can be used to provide direct cooling. In such a case, insertion tubes <b>26</b>, <b>28</b> and/or mask <b>40</b> may not be necessary, and may be discarded if provided. Delivery tube <b>24</b>, insertion tube(s) <b>26</b> and/or <b>28</b>, or other conduit connected to delivery tube <b>24</b> may be inserted into the patient via a natural orifice, wound, incision or other opening to the site where cooling is desired. Application of gas through delivery tube <b>24</b> provides cooling, as discussed above.

0067While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. It will be evident from the specification that aspects or features discussed in one context or embodiment will be applicable in other contexts or embodiments.