Arm immersion cooling apparatus and method

A two person portable apparatus (10) for reducing the core temperature of one or more human beings includes a trough (14) made of a waterproof, flexible fabric (56) and a generally rectangular frame (12). Portions (68, 70, 72, 74) of the fabric (56) are looped over sides (24, 26, 28, 30) of the frame (12) so that the trough is supported by and suspended from the frame. The apparatus includes four legs (16, 18, 20, 22) hinged to corners of the frame and pivotable inwardly under the trough. Cooling water is placed in the trough and the hands and forearms of human beings are immersed in the cooling water.

BACKGROUND OF THE INVENTION

The invention relates in general to reducing the core temperature of human beings and in particular to lightweight, portable, non-powered apparatus and methods for reducing the core temperature of human beings.

Humans engage in physical activities including, for example, workplace operations, exercises, athletic competition and training, emergency rescue operations, and military combat and training. Risks associated with physical activities, particularly physical activities in a hot environment, are heat illness and heat stroke. Exertional heat stroke (EHS) may result when a human engages in strenuous physical activity for a prolonged period of time in a hot environment or when metabolic heat production is sufficiently elevated above resting.

Lowering the human body's elevated core temperature can reduce the risk of EHS. Various methods are known for lowering the body's core temperature. Cooling suits of various types are known. Cooling suits often interfere with the wearer's activity, add additional work burden to the wearer, and are expensive. Cooling suits are practical for some specialized activities, but are not a broadly applicable way of lowering body core temperature in physically active individuals. For large numbers of individuals, for example, soldiers in a training environment or team athletes, methods of avoiding heat stress have included ingesting substantial amounts of water, frequent rest periods, moving the individuals to a shady area, loosening or removing clothing, spraying the individuals with water misters, changing the time of day of training, and changing the order of training events. Nevertheless, decreased performance due to heat stress continues. As stated by R. O'Hara et al. (Current and Future Cooling Technologies Used in Preventing Heat Illness and Improving Work Capacity for Battlefield Soldiers: Review of the Literature, Military Medicine, Volume 173, Number 7, pp. 653-657, July 2008): “Currently, practical cooling devices that provide sustained cooling effects for battlefield soldiers are not available.” (p. 653); and: “Clearly, there is a need for effective portable methods of cooling.” (p. 655).

SUMMARY OF THE INVENTION

One aspect of the invention is an apparatus for reducing the core temperature of one or more human beings. One embodiment of the apparatus includes a fabric piece of waterproof, flexible material having a generally rectangular-shaped major portion with opposing long sides and opposing short sides and four flaps. Each flap extends from a respective one of the opposing long sides and the opposing short sides. The embodiment includes a generally rectangular frame with two short sides and two long sides. Each of the four flaps of the fabric piece is looped over a respective one of the short and long sides of the frame and attached to the major portion of the fabric piece. The major portion of the fabric piece forms sides and a bottom of a collapsible trough supported by and suspended from the frame.

Four legs have first ends disposed generally at four respective corners of the frame. Each leg is hinged at its first end to the frame and pivotable inwardly from an unfolded position of the apparatus, generally perpendicular to a plane of the frame, to a folded position of the apparatus, substantially parallel to the plane of the frame and under the trough. A pair of the legs disposed at one end of the long sides of the frame comprises a first leg section and a pair of the legs disposed at another end of the long sides of the frame comprises a second leg section.

The embodiment includes four longitudinal braces. Two of the braces are pivotally attached at first ends to a respective leg of the first leg section and two of the braces are pivotally attached at first ends to a respective bushing and a respective leg of the second leg section. In the unfolded position of the apparatus, each of the four braces is releaseably fixed to the rectangular frame at second ends of each of the four braces.

A weight of the embodiment is in a range of 45 pounds to 102 pounds. In an unfolded position of the apparatus, the collapsible trough has a fluid capacity in a range of 20 to 48 gallons.

A distance between the pair of legs in the second leg section is less than a distance between the pair of legs in the first leg section such that the first and second leg sections do not interfere in the folded position of the apparatus.

Cross-beams are disposed between the pairs of legs in each leg section. The cross-beams are separate from and spaced apart from a respective short side of the frame. Four corner gussets are disposed in respective internal corners of the frame. In the unfolded position of the apparatus, the four braces are releaseably fixed to long sides of the frame.

Four leg section braces are fixed at one end to a respective leg and at another end to a respective adjacent cross-beam. The leg section braces are diagonally oriented with respect to the legs and cross-beams and disposed further from the frame than the cross-beams in the unfolded position of the apparatus. Leg section gussets are disposed at corner intersections of the cross-beams and the legs on a same side of the cross-beams as the leg section braces.

Another aspect of the invention is a method of reducing the core temperature of a plurality of human beings simultaneously. One embodiment of the method includes providing an embodiment of the apparatus of the invention and placing cooling water in the trough of the embodiment. The hands and forearms of a plurality of human beings are simultaneously immersed in the trough.

An additional aspect of the invention is a method of making an apparatus for reducing the core temperature of one or more human beings. One embodiment of the method includes providing a fabric piece of waterproof, flexible material having a generally rectangular-shaped major portion with opposing long sides and opposing short sides and four flaps. Each flap extends from a respective one of the opposing long sides and the opposing short sides.

The embodiment includes providing a generally rectangular frame with two short sides and two long sides and looping each of the four flaps of the fabric piece over a respective one of the short and long sides of the frame. Then, each of the four flaps is attached to the major portion of the fabric piece.

The invention will be better understood, and further objects, features and advantages of the invention will become more apparent from the following description, taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

An arm immersion cooling apparatus and method utilizes the greater heat transfer coefficient of water, compared to air, and the larger surface area-to-mass ratio of a human being's forearms compared to other body segments. The apparatus and method lower a human's core body temperature primarily by heat transfer through the hands and forearms. The hands and forearms are immersed in a cooling medium, such as water, contained in the apparatus. The apparatus is large enough for immersion of the hands and forearms of up to six adults. If needed, the apparatus can be used to immerse the complete torso of a single human to accelerate the cooling process. The large volume of cooling medium helps accelerate heat transfer from the users. The ease of use facilitates demand for and acceptance of the apparatus.

Importantly, the apparatus is inexpensive to manufacture and is portable by two people. Many features of the apparatus contribute to its two person portability. The weight of the apparatus (without water) is in a range of about of about 45 to about 102 pounds, preferably in the range of about 50 to about 70 pounds, most preferably about 60 pounds. In the transportation (folded) position, the most preferred size of the apparatus is about 62 inches long, 24 inches wide and about 4 inches deep. Of course, variations in the overall dimensions of the apparatus are possible. Exemplary variations are 56 to 68 inches long, 20 to 28 inches wide, and 2 to 8 inches deep. The inventive apparatus can accommodate up to six adults simultaneously for hand and forearm immersion or one adult for torso immersion. The apparatus is low maintenance, sized for ease of transport, easy to set up for use, and easy to take down for transportation.

FIGS. 1A-1Dare front, top, left end, and right end views, respectively, of one embodiment of an apparatus10for cooling one or more human beings. Of course, embodiments of the invention that differ from apparatus10may be included in the literal or equivalent scope of the patent claims.

Apparatus10includes a generally rectangular frame12and four legs16,18,20,22. A collapsible trough14is supported by and suspended from frame12. Legs16-22have respective first ends16a,18a,20a,22adisposed generally at four respective corners of frame12. Legs16-22are hinged at first ends16a-22ato frame12. Hinges13are used to mount legs16-22to frame12. From the unfolded position (shown inFIGS. 1A-D) where legs16-22are generally perpendicular to the plane of frame12, legs16-22are inwardly pivotable to a folded position where legs16-22are substantially parallel to the plane of frame12and disposed under trough14.

Apparatus10includes four longitudinal braces44,46,48,50.FIGS. 10A and 10Bare detailed views of braces44,46,48,50. Two of the braces44,46are pivotally attached at first ends44a,46ato respective legs16,18and two of the braces48,50are pivotally attached at first ends48a,50ato respective bushings52,54(FIGS. 7A-B) and legs20,22. The first ends44a-50aof braces44-50are attached using fasteners inserted in openings96(FIG. 6A) in legs16-22.

In the unfolded position of apparatus10shown inFIGS. 1A-D, second ends44b,46b,48b,50bof each of the four braces44-50are releaseably fixed to rectangular frame12. Quick-release pins86are used for releaseably fixing the four braces44-50to frame12. Pins86pass through grommets90(FIG. 2) placed in openings77(FIG. 4) in flaps70,74and through openings29(FIGS. 3A and 3C) in long sides28,30of frame12. A lanyard88is provided for each pin86. One end of lanyard88is fixed to pin86and another end of lanyard88is fixed to a fastener in opening104(FIG. 10A) in braces44-50. Cinching straps106, for example, straps with hook and loop fasteners, are also fixed to a fastener in opening104. Straps106are used to secure legs16-22in the folded position parallel to the plane of frame12.

FIG. 2is a perspective view of frame12and trough14of apparatus10. Frame12includes long sides28,30and short sides24,26. Frame12is made of a lightweight metal, such as, for example, aluminum or aluminum alloy. Frame12may also be made of non-metallic materials, such as plastics, for example. Sides24,26,28,30may have various shapes or cross-sections. Adequate strength and low weight are important factors for all components of apparatus10, including frame12. In one embodiment, frame12is made of aluminum and sides24-30have a cross-section shown in the end view of sides28,30inFIG. 3B. Ends of sides24-30are joined by, for example, castle corners25. Corner gussets84are fixed in each of the four internal corners of frame12. Hinges13are mounted on short side26at one end of frame12and on long sides28,30at the other end of frame12. Components of frame12are available from, for example, Frame-World, Inc., 9116 Virginia Road, Lake in the Hills, Ill. 60156 USA.

FIG. 4is a plan view of a fabric piece56used to construct trough14. Fabric piece56is a waterproof, flexible fabric (for example, tent fabric) having a generally rectangular-shaped major portion58with opposing long sides60,62and opposing short sides64,66. Horizontal and vertical center lines of fabric piece56are shown by broken lines. Four exemplary fold lines of fabric piece56are also shown in broken lines. Four flaps68,70,72,74extend from respective sides66,60,64,62. As shown inFIG. 2, each of the four flaps68-70of fabric piece56is looped over a respective one of the sides26,30,24,28of frame12and attached to major portion58of fabric piece56using, for example, one or more rows of stitching59(FIGS. 1A, 1C, 1D). Major portion58of fabric piece56forms the sides and bottom of trough14. Opening75(FIG. 4) in fabric piece56is fitted with a grommet79(FIG. 1B). A drain fitting76(FIG. 1A) is threaded in grommet79. A drain hose78with a shut-off valve79is connected to drain fitting76for selectively draining water from trough14. Webbing strips57(FIG. 2) are stitched around the upper portion of the corners of trough14for reinforcement.

For effective immersion of the hands and forearms, the depth of cooling medium, for example, water, in trough14should be at least about three inches. Preferably, the depth of water in trough14is from four to six inches and the volume of water is about 20 to 48 gallons, preferably about 37-40 gallons. A time/temperature table108(FIG. 1B) may be stenciled on the bottom of trough14for easy reference by users. A durable thermometer (not shown) may be fixed in trough14and used in conjunction with table108.

The top surfaces of the four sides24-30of frame12are preferably rounded to reduce wear on fabric piece56. One way to round the top surfaces is to insert concave rail inserts102(FIGS. 9A and 9B) into the top surface of each side24-30.

The pair of legs16,18disposed at one end of long sides28,30of frame12comprises a first leg section40(FIG. 5A) and the pair of legs20,22disposed at another end of long sides28,30of frame12comprises a second leg section42(FIG. 5B). The distance A between the pair of legs20,22in second leg section42is less than the distance B between the pair of legs16,18in the first leg section40such that the first and second leg sections40,42do not interfere in the folded position of apparatus10. That is, when leg sections40,42are pivoted inwardly towards each other under the trough14, legs16,18are offset from legs20,22so that both pairs of legs may be fully folded parallel to the plane of frame14without interference between the legs. The offset feature of the leg sections is important when the length of the legs is more than about one half the length of apparatus10.

Each leg section40,42includes a cross-beam82disposed between the pairs of legs in each leg section. Cross-beam82is shown in detail inFIGS. 8A and 8B. Cross-beams82are separate from and spaced apart from respective short sides26,24(FIG. 2) of frame12. Each leg section40,42includes a pair of diagonal braces92. Each brace92is fixed at one end to a respective leg16-22and at another end to a respective adjacent cross-beam82. Braces92are diagonally oriented with respect to legs16-22and cross-beams82and disposed further from frame12than cross-beams82. Gussets94are disposed at the intersection of cross-beams82and legs16-22on the same side of cross-beams82as diagonal braces92.

Legs16-22may have the shape or cross-section shown inFIGS. 6A-C. Adjusters98(FIGS. 5A-B) are provided on each leg to help level apparatus10. Adjusters98thread into openings100(FIGS. 6A and 6B) in the bottom of each leg. Adjusters98are primarily for leveling apparatus10and not intended to vary the overall working height of apparatus10. Legs with a large amount of length adjustment, such as telescoping legs, add undesirable cost and weight to the apparatus. In this regard, the length of legs16-22is generally fixed and represents a compromise to accommodate humans of greater or lesser than average stature. Legs16-22have a length in the range of about 30 to about 43 inches, and preferably about 35 to about 38 inches.

For transportation and storage, apparatus10is in a folded position (not shown) with leg sections40,42pivoted under collapsed trough14and substantially parallel to the plane of frame12. To use apparatus10, cinching straps106are disengaged so that leg sections40,42may be pivoted away from trough14and perpendicular to frame12. The second ends44b,46b,48b,50bof each of the four braces44,46,48,50are pivoted upward toward frame12. Quick-release pins86are inserted through openings110(FIG. 10A) in second ends44b-50band through openings29(FIGS. 3A and 3C) in long sides28,30of frame12. Leg adjusters98are used to level apparatus10. Cooling water is then placed in trough14to a depth of at least three inches and preferably more, up to six inches.

The cooling water temperature should be no more than 80 degrees F. Preferably, the cooling water is cooler than 80 degrees F. but no cooler than 35 degrees F. Up to six users may then simultaneously immerse their hands and forearms in trough14. Depending on the temperature of the cooling water, the length of time of immersion may vary, for example, from three minutes to fifteen minutes, as shown by the time/temperature table108inFIG. 1B. Prior to or when the water in the trough has warmed to above 80 degrees F., some or all of the water can be drained out of the trough14through drain fitting76and hose78and cooler water can added to trough14.

Because of the relatively short immersion time required, a single apparatus10may be sufficient for cooling a group of 16 to 44 individuals. A plurality of apparatus10may, of course, be used.

User acceptance of any new product, apparatus, or technique is highly unpredictable. Multiple apparatus10were distributed for testing to the U.S. Army Airborne School, Ranger Training Brigade, Ft. Benning, Ga. Initial results indicate positive user acceptance, reduction in heat injuries and heat stroke, and improved soldier performance. Additional apparatus10have been requested and mass production of apparatus10is planned. Non-military uses may include sports teams, athletic events, and civilian occupations in hot environments.

The details, materials, steps and arrangement of parts have been described and illustrated to explain the nature of the invention. It will be understood that many changes in the details, materials, steps and arrangement of parts may be made by those skilled in the art, within the principle and scope of the invention, as expressed in the appended claims and equivalents thereof.