Patent Publication Number: US-9835344-B2

Title: System for support and thermal control

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/588,784, filed Jan. 20, 2012, which is incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates generally to support surfaces for independent use and for use in association with beds and other support platforms, and more particularly but not by way of limitation to support surfaces that aid in the prevention, reduction, and/or treatment of decubitus ulcers and the transfer of moisture and/or heat from the body. 
     BACKGROUND 
     Patients and other persons restricted to bed for extended periods incur the risk of forming decubitus ulcers. Decubitus ulcers (commonly known as bed sores, pressure sores, pressure ulcers, etc.) can be formed when blood supplying the capillaries below the skin tissue is interrupted due to external pressure against the skin. This pressure can be greater than the internal blood pressure within a capillary and thus, occlude the capillary and prevent oxygen and nutrients from reaching the area of the skin in which the pressure is exerted. Moreover, moisture and heat on and around the person can exacerbate ulcers by causing skin maceration, among other associated problems. 
     SUMMARY 
     Exemplary embodiments of the present disclosure are directed to apparatus, systems and methods to reduce a patient&#39;s skin temperature and to aid in the prevention of decubitus ulcer formation and/or promote the healing of such ulcer formation. 
     In various embodiments, a support system cooling device (SSCD) comprises multiple layers configured to allow air flow through the layers and towards an air mover. Exemplary embodiments incorporate an air mover configured to provide air flow from approximately 1.0 cubic feet per minute (CFM) to approximately 50 CFM. Such air flow can provide high vapor transfer rates, including for example, those in excess of 500 gm/m2/hr. Additionally, with the higher air flow rates proximal to the patient, the skin temperature of the patient has calculated to be reduced to approximately 88 degrees Fahrenheit. 
     In certain embodiments, the SSCD comprises a support portion underneath a patient, while in other embodiments, the SSCD also comprises a cover portion configured to cover a patient. The support (and optionally, cover) portion are coupled to the air mover via a plurality of conduits that allow for air flow sufficient to provide moisture removal from a patient and conductive cooling to the skin of a patient. 
     Certain embodiments comprise a support surface cooling device comprising: an air mover; a first conduit; a first layer comprising a vapor permeable material; a second layer comprising a spacer material; and a third layer. In particular embodiments, the second layer is between the first layer and the third layer; the first conduit is in fluid communication with the second layer and the air mover; and the air mover is configured to create air flow through the spacer material toward the air mover. In certain embodiments, the first conduit is embedded within the second layer. 
     Certain embodiments comprise a support surface cooling device comprising: an air mover; a first layer comprising a vapor permeable material; a second layer comprising a spacer material; and a third layer, wherein: the second layer is between the first layer and the third layer; the air mover is configured to create air flow through the spacer material toward the air mover; and the air mover is configured to provide air flow between approximately 5 standard cubic feet per minute and approximately 50 standard cubic feet per minute. 
     In specific embodiments, the air mover is configured to provide air flow between approximately 5 standard cubic feet per minute and approximately 50 standard cubic feet per minute. In certain embodiments, the air flow is between approximately 10 standard cubic feet per minute and 50 standard cubic feet per minute, while in particular embodiments, the air flow is between approximately 20 standard cubic feet per minute and 50 standard cubic feet per minute. 
     In certain embodiments, the air mover is configured to create air flow sufficient to provide conductive cooling to the skin of a patient adjacent to the first layer. In particular embodiments, the spacer material comprises one of the following: open cell foam; natural or synthetic polymer particles, filaments, or strands; cotton fibers; polyester fibers; flexible metals and metal alloys; shape memory metals and metal alloys, and shape memory plastics. Specific embodiments may also comprise an antimicrobial device proximal to the air mover. In particular embodiments, the air mover is a centrifugal fan. Certain embodiments may comprise an antimicrobial device proximal to the air mover. 
     In particular embodiments, the support surface cooling device is configured to permit an air flow of 30 standard cubic feet per minute through the spacer material while supporting a person laying on the spacer material. In certain embodiments, the first layer, second layer and third layer are components of a support portion configured to be placed between a patient and a support mattress. Specific embodiments, may comprise a cover portion configured to cover a patient supported by the support mattress. Particular embodiments, may also comprise a second conduit in fluid communication with an air space between the support portion and the cover portion. In specific embodiments, the support portion and the cover portion are coupled together via a coupling mechanism. In particular embodiments, the coupling mechanism is selected from the group consisting of zippers, buttons, snaps, or stitching. Specific embodiments comprise a plurality of conduits in fluid communication with the second layer and the air mover. 
     Particular embodiments also include a method of reducing the skin temperature of a patient, where the method comprises providing a support surface cooling device comprises an air mover; a conduit; a vapor permeable layer; and a spacer material adjacent the vapor permeable layer, wherein the conduit is in fluid communication with the air mover and the spacer material. Certain embodiments also comprise placing the vapor permeable layer adjacent a skin surface of the patient; operating the air mover to create an air flow through the spacer material and the conduit toward the air mover; and reducing the skin temperature of the patient. In particular embodiments, the air flow is between approximately 5 standard cubic feet per minute and 30 standard cubic feet per minute, or between approximately 10 standard cubic feet per minute and 30 standard cubic feet per minute, or between approximately 20 standard cubic feet per minute and 30 standard cubic feet per minute. 
     In certain embodiments, the vapor permeable layer and the spacer material are placed between the patient and a support mattress. In particular embodiments, the vapor permeable layer and the spacer material are placed on top of the patient. In specific embodiments, the vapor permeable layer and the spacer material are placed both on top of the patient and between the patient and a support mattress. In certain embodiments, the spacer material comprises one of the following: open cell foam; natural or synthetic polymer particles, filaments, or strands; cotton fibers; polyester fibers; flexible metals and metal alloys; shape memory metals and metal alloys, and shape memory plastic. In particular embodiments, the skin temperature of the patient is reduced via conductive cooling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While exemplary embodiments of the present invention have been shown and described in detail below, it will be clear to the person skilled in the art that changes and modifications may be made without departing from the scope of the invention. As such, that which is set forth in the following description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined by the following claims, along with the full range of equivalents to which such claims are entitled. 
       In addition, one of ordinary skill in the art will appreciate upon reading and understanding this disclosure that other variations for the invention described herein can be included within the scope of the present invention. For example, portions of the support system shown and described may be incorporated with existing mattresses or support materials. Other embodiments may utilize the support system in seating applications, including but not limited to, wheelchairs, chairs, recliners, benches, etc. 
       In the following Detailed Description of Disclosed Embodiments, various features are grouped together in several embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that exemplary embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description of Disclosed Embodiments, with each claim standing on its own as a separate embodiment. 
         FIG. 1  illustrates a side view of a first exemplary embodiment of a support surface cooling device and a support mattress supporting a person. 
         FIG. 2  illustrates a cross-sectional end view of the device of  FIG. 1  take along line  2 - 2  of  FIG. 1 . 
         FIG. 3  illustrates a detailed cross-sectional view of a support surface cooling device adjacent a skin surface. 
         FIG. 4  illustrates a graph of predicted skin temperature versus air flow. 
         FIG. 5  illustrates a side view of a second exemplary embodiment of a support surface cooling device and a support mattress supporting a person. 
         FIG. 6  illustrates a side view of a third exemplary embodiment of a support surface cooling device and a support mattress supporting a person. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     Exemplary embodiments of the present disclosure are directed to apparatus, systems and methods to aid in the prevention of decubitus ulcer formation and/or promote the healing of such ulcer formation. For example, in various embodiments, reducing skin temperature, preventing ulcer formation and/or healing decubitus ulcers can be accomplished through the use of a support surface cooling device. Exemplary embodiments of the device can be utilized to aid in the removal of moisture, vapor, and heat adjacent and proximal the patient surface interface and in the environment surrounding the patient by providing a surface that absorbs and/or disperses the moisture, vapor, and heat from the patient. In addition, the exemplary embodiments of the device can be utilized in combination with a number of support surfaces or platforms to provide a reduced interface pressure between the patient and the device on which the patient is positioned. This reduced interface pressure can help to prevent the formation of decubitus ulcers. 
     In various exemplary embodiments, the support surface cooling device may include a number of layers. Each layer may be formed of a number of different materials that exhibit various properties. These properties may include the level of friction or shear of a surface, the permeability of a vapor, a gas, a liquid, and/or a solid, and various phases of the vapor, the gas, the liquid, and the solid, and other properties. 
     For example, in exemplary embodiments, the support surface cooling device may include materials that provide for a low air loss feature, where one or more layers exhibit various air, vapor, and liquid permeable properties and/or where one or more layers are bonded or sealed together. As used herein, a low air loss feature of a support surface cooling device includes, but is not limited to: a multi-layer device that allows air and vapor to pass through the first layer in the presence of a partial pressure difference in vapor between the internal and external environments of the multi-layer device; a multi-layer device that allows air and vapor to pass through the first layer in the absence of a partial pressure difference in vapor between the internal and external environments of the multi-layer device; and a multi-layer device that allows air and vapor to move into and/or out of the multi-layer device through the apertures in one or more layers. 
     In other exemplary embodiments, the multi-layer device can include materials that provide for substantially no air flow, where one or more layers include air impermeable properties and/or where layers are bonded or sealed together to a layer comprising a spacer material. In such exemplary embodiments, this configuration may control the direction of movement of air from outside to inside (e.g., under influence by a source of negative pressure at the air inlet for the multi-layer device). Certain exemplary embodiments comprise a multi-layer device including, but is not limited to, the following: a device that prevents or substantially prevents air from passing through the first layer, but allows for the passing of vapor through the first layer; a device that prevents or substantially prevents air from moving through the first layer in the presence of a partial vapor pressure difference between the internal and external environments of the multi-layer device, but allows for the passing of vapor through the first layer; and a device that prevents or substantially prevents air from moving out of the multi-layer device via the material forming a particular layer of the device, but allows air to move through the apertures in one or more layers. 
     In various exemplary embodiments, systems are provided that can include a number of components that both aid in prevention of decubitus ulcer formation and to remove moisture and/or heat from the patient. For example, systems can include a support surface cooling device (SSCD) that can be used in conjunction with a variety of support surfaces, such as an inflatable mattress, a foam mattress, a gel mattress, a water mattress, or fluid mattress of a hospital bed. In such exemplary embodiments, features of the SSCD can help to remove moisture and heat from the patient and to lower interface pressure between a patient and the surface of the SSCD, while features of the inflatable or foam mattress can aid in the prevention and/or healing of decubitus ulcers by further lowering interface pressures at areas of the skin in which external pressures are typically high, as for example, at bony prominences such as the heel and the hip area of the patient. In other exemplary embodiments, systems can include the SSCD used in conjunction with a chair or other support platform. 
     Referring now to  FIG. 1 , an exemplary embodiment of a support surface cooling device (SSCD)  500  is shown placed on a support mattress  560  and beneath a patient  180 . In this embodiment, SSCD  500  comprises support portion  505  with a water vapor-permeable first layer  510 , a middle layer  520  comprising a spacer material, and a third layer  530 . In the embodiment shown, first layer  510  is proximal to patient  180 , while third layer  530  is distal to patient  180 . 
     In this embodiment, support portion  505  is also coupled to air mover  540  via a plurality of conduits  545  that can allow for substantial air flow  541  from middle layer  520  to air mover  540 . In certain embodiments, conduits  545  may be embedded in middle layer  520 . In other exemplary embodiments, air mover  541  can be configured to provide air flow  541  to middle layer  520  without the use of conduits. For example, air mover  541  may be directly coupled to support portion  505  such that air flow  541  is directed to middle layer  520 . In certain embodiments, air mover  540  is capable of providing between approximately 5 and 50 standard cubic feet per minute (SCFM) of air flow between support portion  505  and air mover  540 . In particular embodiments, air mover  540  is capable of providing between approximately 10 SCFM and 50 SCFM or between approximately 20 SCFM and 50 SCFM of air flow between support portion  505  and air mover  540 . As explained in further detail below, such air flow can provide for vapor transfer rates sufficient to reduce the skin temperature of the patient. 
     The general principles of operation for this exemplary embodiment are provided initially, followed by a more detailed description of individual components and principles of operation. In general, moisture vapor  116  is transferred from a patient  180 , through first layer  510 , to air contained in middle layer  520 . In exemplary embodiments, air mover  540  pulls air through middle layer  520  (e.g., via conduits  545 ) so that moisture vapor  116  can be removed from the air contained in middle layer  520 . In addition, air flow  541  reduces the temperature of the patient&#39;s skin. The use of negative air pressure to draw room temperature air into the coverlet causes moisture vapor from patient  180  to evaporate. This can cause a cooling of the air inside support portion  505  and provide an inductive cooling to patient  180 . In addition air flow  541  in middle layer  520  can be a lower temperature than the skin temperature of patient  180 , which can provide conductive cooling of patient  180 . 
     In certain embodiments, first layer  510  is comprised of a material that is liquid and air impermeable and either vapor permeable or vapor impermeable. One example of such vapor permeable material is sold under the trade name GoreTex™. GoreTex™ is vapor permeable and liquid impermeable, but may be air permeable or air impermeable. Examples of such vapor impermeable materials include sheet vinyl or sheet urethane. In the embodiment shown, middle layer  520  comprises a spacer material that separates first layer  510  and third layer  530 . As used in this disclosure, the term “spacer material” (and related terms) should be construed broadly to include any material that includes a volume of air within the material and allows air to move through the material. In exemplary embodiments, spacer materials allow air to flow through the material when a person is laying on the material while the material is supported by a mattress. Examples of such spacer materials include open cell foam, polymer particles, and a material sold by Tytex under the trade name AirX™. 
     In the exemplary embodiment shown, third layer  530  comprises a material that is vapor impermeable, air impermeable, and liquid impermeable. Examples of such material include sheet vinyl plastic or sheet polyurethane material. First layer  510  and third layer  530  may be comprised of the same material in certain embodiments. 
     Support mattress  560  can be any configuration known in the art for supporting person  180 . For example, in certain exemplary embodiments, support mattress  560  may be an alternating-pressure-pad-type mattress or other type of mattress utilizing air to inflate or pressurize a cell or chamber within the mattress. In other exemplary embodiments, support mattress  560  does not utilize air to support person  180  and may comprise, for example, foam, gel, water, or other suitable support materials. 
     Referring still to  FIG. 1 , support mattress  560  and support portion  505  provide support for person  180  and aid in the removal of moisture, vapor and heat adjacent and proximal the interface between person  180  and support portion  505 . In the exemplary embodiment of  FIG. 1 , SSCD  500  comprises a plurality of conduits  545  that are in fluid communication with both the air mover  540  and the spacer material of middle layer  520 . During operation, air mover  540  shown in  FIG. 1  operates to reduce pressure within support portion  505  and create a negative pressure or suction air flow  541  that is directed through middle layer  520  and toward air mover  540 . 
     Referring now to  FIG. 2 , a cross-section end view of support portion  505  illustrates the multiple layers. During operation of SSCD  500 , moisture vapor  116  is transferred from person  180  (and the air adjacent person  180 ) through first layer  510  to air pockets within the spacer material of middle layer  520 . Moisture vapor  116  will continue to transfer to air pockets within spacer material  522  while the air pockets are at a lower relative humidity than the air adjacent person  180 . As the relative humidity of the air pockets increases and approaches the relative humidity of the air adjacent person  180 , the transfer rate of moisture vapor  116  will decrease. It is therefore desirable to maintain a lower relative humidity of the air pockets within middle layer  520  than the relative humidity of the air adjacent person  180 . As moisture vapor  116  is transferred to air pockets within middle layer  520 , it is desirable to remove moisture vapor from the air pockets and lower the relative humidity of the air within middle layer  520 . The relative humidity of air in middle layer  520  can be reduced to that of the surrounding environment. By removing moisture vapor  116  from the air within middle layer  520 , the transfer rate of moisture vapor  116  from person  180  can be maintained at a more uniform level. 
     In the exemplary embodiment shown in  FIGS. 1 and 2 , air flow  541  flows through the air pockets within middle layer  520  and assists in removing moisture vapor  116  from the air pockets. This lowers the relative humidity of the air pockets and allows the transfer rate of moisture vapor  116  to be maintained over time. As shown in  FIGS. 1 and 2 , air flow  541  can be drawn or pulled through middle layer  520  toward air mover  540 . As explained in more detail below, the skin temperature of patient  180  can be reduced during operation of SSCD  500 . 
     Referring now to  FIG. 3 , a detailed sectional view of support portion  505  is shown adjacent the skin of patient  180 . Without desiring to be bound by theory, the skin temperature of patient  180  can be calculated by the following formula (assuming the skin is dry without sweating): 
               T   skin     =           (       T   core     -     T   ambient       )     ×     R   system         (       R   system     +     R   skin       )       +     T   ambient             
where:
         T skin =the patient&#39;s external skin temperature   T core =the patient&#39;s skin core temperature (37° C./98.6° F.)   T ambient =the ambient temperature (25° C./77° F.)   R system −SSCD resistance to heat transfer   R skin =skin resistance to heat transfer (0.05 m 2 ° K/W)       

     The use of negative pressure to create air flow allows room temperature air to flow into SSCD  500 , creating a greater temperature differential between the surrounding air and the skin of patient  180 . In addition, negative pressure draws first layer  510  and third layer  530  against the spacer material of middle layer  520 . This can direct air flow  541  through middle layer  520 , creating a higher air velocity of air flow  541  and expedite the evaporation of moisture vapor  116 . If positive air pressure (e.g. air flow  541  directed away from air mover  540 ) were utilized instead, it could separate the first layer  510  or third layer  530  from middle layer  520 . This billowing of first layer  510  or third layer  530  can allow airflow  541  to bypass the spacer middle layer  520 , and the velocity of airflow  541  within middle layer  520  to be reduced. The reduced airflow velocity also reduces the ability of SSCD to remove moisture vapor from patient  180  and lower the skin temperature of patient  180 . 
     Referring now  FIG. 4 , a graph illustrates the predicted skin temperature of a patient with use of SSCD  500 . As shown in  FIG. 4 , the predicted skin temperature is reduced from approximately 97.5° F. with no airflow to approximately 88° F. with maximum airflow of approximately 30 cubic feet per minute (CFM). Various sizes of air movers were used in testing. In this test example, the air mover was an Ametek® model 119103-00 Type H, 8 amp, 50/60 Hz, 120 V, with maximum air flow of over 100 CFM. 
     As one of ordinary skill in the art will appreciate, vapor and air can carry organisms such as bacteria, viruses, and other potentially harmful pathogens. As such, and as will be described in more detail herein, in some embodiments of the present disclosure, one or more antimicrobial devices, agents, etc., can be provided to prevent, destroy, mitigate, repel, trap, and/or contain potentially harmful pathogenic organisms including microbial organisms such as bacteria, viruses, mold, mildew, dust mites, fungi, microbial spores, bioslimes, protozoa, protozoan cysts, and the like, and thus, remove them from air and from vapor that is dispersed and removed from the patient and from the environment surrounding the patient. In addition, in various embodiments, the SSCD  500  can include various layers having antimicrobial activity. In some embodiments, for example, first, middle and third layers,  510 ,  520  and  530  can include particles, fibers, threads, etc., formed of silver and/or other antimicrobial agents. 
     In various exemplary embodiments, middle layer  520  can be formed of various materials, and can have a number of configurations and shapes, as described herein. In some embodiments, the material is flexible. In such exemplary embodiments, the flexible material can include properties that resist compression, such that when the flexible material is compressed, for example, by the weight of a patient lying on support portion  505 , the flexible material has a tendency to return toward its original shape, and thereby impart a supportive function to support portion  505 . The flexible material can also include a property that allows for lateral movement of air through the flexible material even under compressive loads. 
     Examples of materials that can be used to form middle layer  520  can include, but are not limited to, natural and synthetic polymers in the form of particles, filaments, strands, foam (e.g., open cell foam), among others, and natural and synthetic materials such as cotton fibers, polyester fibers, and the like. Other materials can include flexible metals and metal alloys, shape memory metals and metal alloys, and shape memory plastics. These materials can include elastic, super elastic, linear elastic, and/or shape memory properties that allow the flexible material to flex and bend and to form varying shapes under varying conditions (e.g., compression, strain, temperature, etc.). 
     In various exemplary embodiments, SSCD  500  can be a one-time use device or a multi-use device. As used herein, a one-time use device is a device for single-patient use applications that is formed of a vapor, air, and liquid permeable material that is disposable and/or inexpensive and/or manufactured and/or assembled in a low-cost manner and is intended to be used for a single patient over a brief period of time, such as an hour(s), a day, or multiple days or weeks. As used herein, a multi-use device is a device for multi-patient use that is generally formed of a vapor permeable, liquid impermeable and air permeable or air impermeable material that is re-usable, washable, can be disinfected using a variety of techniques (e.g., autoclaved, bleach, etc.) and generally of a higher quality and superior in workmanship than the one-time use device and is intended to be used by one or more patients over a period of time such as multiple days, weeks, months, and/or years. In various exemplary embodiments, manufacturing and/or assembly of a multi-use device can involve methods that are more complex and more expensive than one-time use device. Examples of materials used to form one-time use devices can include, but are not limited to, non-woven papers. Examples of materials used to form re-usable devices can include, but are not limited to, Gore-Tex®, and urethane laminated to fabric. 
     Referring now to  FIG. 5 , in certain embodiments an SSCD  600  may comprise a cover portion  610  configured to cover patient  180  in addition to a support portion  620  between patient  180  and support mattress  560 . In certain exemplary embodiments, support portion  620  is configured equivalent to SSCD  500  and cover portion  610  is configured equivalent to an inverted SSCD  500 . For example, cover portion  610  may comprise three layers, including a first layer proximal to patient  180  that is equivalent to first layer  510 , a middle layer equivalent to middle layer  520 , and a third layer proximal to the environment that is equivalent to third layer  530 . 
     SSCD  600  also comprises a plurality of conduits  645  in fluid communication with air mover  540  and cover portion  610  and support portion  620 . During operation, SSCD  600  can also serve to remove moisture vapor and decrease the skin temperature of patient  180  in a manner generally equivalent to that of SSCD  500  described previously. SSCD  600 , however, may provide for more effective moisture vapor removal and skin temperature reduction by covering more skin surface area of patient  180  than embodiments that only include a support portion underneath patient  180 . 
     Referring now to  FIG. 6 , in certain embodiments an SSCD  700  may comprise a cover portion  710  that is coupled to a support portion  720 . In particular embodiments, cover portion  710  may be coupled to support portion  720  via a coupling mechanism  730 . In specific embodiments, coupling mechanism  730  may comprise one or more zippers, buttons, snaps or other suitable devices. In other embodiments, cover portion  710  and support portion may be sewn or stitched together to form a unitary component similar to a sleeping bag. Similar to previously-described embodiments, this embodiment comprises a plurality of conduits  645  in fluid communication with air mover  540  and cover portion  710  and support portion  720 . In addition, this embodiment comprises a conduit  755  directed to the air space between cover portion  710  and support portion  720 . During operation, conduit  755  can reduce the pressure in the air space between cover portion  710  and support portion  720  and draw cover portion toward patient  180  and support portion  720 . During operation, SSCD  700  can also serve to remove moisture vapor and decrease the skin temperature of patient  180  in a manner generally equivalent to that of SSCD  600  described previously.