Patent Publication Number: US-7712164-B2

Title: Method and apparatus for improving air flow under a patient

Description:
RELATED APPLICATIONS 
   This application is a continuation of U.S. application Ser. No. 11/243,664, which was filed Oct. 5, 2005, which is scheduled to issue as U.S. Pat. No. 7,469,432 on Dec. 30, 2008, and which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/616,246, filed Oct. 6, 2004, each of which is incorporated herein by this reference. 
   This application is related to U.S. patent application Ser. No. 11/119,980, filed May 2, 2005, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/567,215, filed Apr. 30, 2004, both of which are assigned to the assignee of the present invention and expressly incorporated by reference herein. 

   TECHNICAL FIELD 
   The present invention relates to an overlay for a patient support such as a sleeping and/or seating surface (i.e. a hospital bed, mattress, pad, cushion, or bladder). The present invention also relates to method for improving air flow under a patient supported by a patient support. 
   BACKGROUND 
   Hospital beds include a variety of types of mattresses that may have inflatable portions or may be filled with three dimensional engineered material, traditional foam, or other suitable fill material. Hospital beds are often articulatable; for example, the head and/or foot sections may be raised or lowered. In addition, hospital beds often include features directed to the prevention/treatment of decubitus ulcers (bedsores), and/or therapies such as pulmonary rotational therapy, or percussion/vibration therapy. Additionally, it is known to use inflatable mattresses with a variety of inflatable cell/zone structures. 
   Exemplary hospital beds and mattresses are disclosed in, for example, U.S. Pat. No. 4,949,413 to Goodwin, U.S. Pat. No. 5,647,079 to Hakamiun et al., U.S. Pat. No. 6,269,504 to Romano et al., and U.S. Pat. No. 5,926,884 to Biggie et al., which are all assigned to the assignee of the present invention and all of which are expressly incorporated by reference herein. 
   SUMMARY 
   In accordance with the present invention, an overlay, cover, pad or coverlet for a patient support is provided. In one embodiment, a mattress overlay is provided. The overlay includes a cover, a base coupled to the cover, an interior region defined by the base and the cover, a valve operably coupled to the interior region, an air supply operably coupled to the valve and configured to provide air to the interior region, and a fiber network located within the interior region. The fiber network includes a top portion, a bottom portion, and a middle portion. The middle portion includes a plurality of fibers and air spaces, the fibers each having a first portion coupled to the top portion and a second portion coupled to the bottom portion. The cover may include a plurality of apertures configured to allow air to pass through the cover. The base may be formed from a breathable material. The top and bottom portions may include a woven material. The fiber network may include resilient fibers. The fiber network may be stretchable in at least two directions. 
   The mattress overlay may include first and second spaced apart longitudinal sides and first and second spaced apart ends, and the fiber network may be secured to at least one of the sides and ends. The fiber network may be secured by at least one coupler within the interior region. 
   The mattress overlay may include first and second spaced apart longitudinal sides and first and second spaced apart ends defined by the dimensions of the base and the cover and the dimensions of the base and the cover are sized to support at least a portion of a patient. The dimensions may be sized to correspond to the dimensions of a patient support upon which the mattress overlay is to be placed. 
   The mattress overlay may include first and second spaced apart longitudinal sides and first and second spaced apart ends and the valve may be coupled to the first end. 
   The mattress overlay may further include an outlet valve coupled to the second end. 
   In another embodiment, a mattress overlay is provided, including a cover defining an interior region, a three-dimensional fiber network located in the interior region, an inlet valve coupled to the interior region, an air supply coupled to the inlet valve, and a controller coupled to the inlet valve and the air supply to control air flow from the air supply to the interior region of the overlay. 
   The cover may include a top portion and a bottom portion coupled to the top portion at an edge, and the cover has first and second spaced apart longitudinal sides and first and second spaced apart ends. The three dimensional fiber network may be coupled to at least one of the sides and ends of the cover. The fiber network may have an outer edge substantially aligned with the edge of the cover. 
   The level of air flow from the air supply to the controller may be adjustable. The overlay may further include a sensor located within the interior region, wherein the sensor detects a condition and transmits information about the condition to the controller, and the controller adjusts the air flow from the air supply to the interior region based on information received by the controller. The condition may be at least one of: humidity within the interior region, air pressure within the interior region, pressure at an interface between the cover and a patient positioned on the overlay, temperature within the interior region, and weight of a patient positioned on the overlay. The controller may include an input device. The controller may receive input through the input device from one of a patient and a caregiver and the controller may adjust the air flow from the air supply to the interior region based on the input. 
   In another embodiment, a method of improving air flow under a patient is provided. The method includes the steps of providing a patient support configured to support a patient; providing an overlay, the overlay including a cover having a plurality of apertures, a base coupled to the cover, an interior region defined by the cover and the base, and a fiber network located within the interior region; positioning the overlay above the patient support; and forcing air from a air supply into the interior region allowing air to exit the interior region through the plurality of apertures. 
   Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode of carrying out the invention as presently perceived. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The detailed description of the drawings particularly refers to the accompanying figures in which: 
       FIG. 1  is a perspective view of a mattress overlay including a cutaway portion showing a cross section of an interior region, a three dimensional engineered material located within the interior region, and a cover including a magnified portion showing a plurality of apertures; 
       FIG. 2  is a diagrammatic end view of another mattress overlay connected to an air source and placed over a mattress; 
       FIG. 3  is a simplified block diagram illustrating components of an overlay in accordance with the present invention; 
       FIG. 4  is a simplified cross-sectional view of an exemplary three-dimensional material taken along line  4 - 4  of  FIG. 1 ; and 
       FIG. 5  is another simplified cross-sectional view of the three-dimensional material of  FIG. 4  taken along line  5 - 5  of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   The embodiments described below and shown in the figures are exemplary and are not intended to limit the invention to the precise forms disclosed. Instead, the embodiments were selected for description to enable one of ordinary skill in the art to practice the invention. 
   In accordance with the present invention, an overlay is provided to improve air flow under a patient positioned on a patient support. The patient support is, for example, a bed or a chair. The illustrated embodiments of the overlay are sized to substantially coincide with the area of the patient support that is configured to support a patient. The overlay may take the form of a pad, coverlet, mattress insert, fitted cover or fitted sheet, or similar suitable configuration. The overlay is positionable on top of a mattress or cushion. The overlay is also positionable within the interior region of a mattress. In certain embodiments, the length and width dimensions of the overlay substantially correspond to the length and width dimensions of a patient support on which the overlay may be positioned. 
   As shown in  FIG. 1 , a mattress overlay  10  includes a cover or top layer  12 , a base or bottom layer  14  coupled to cover  12 , an edge  15 , an inlet valve  16  and an interior region  18  defined between cover  12  and base  14 , shown at cutaway portion  17 . Interior region  18  includes a three dimensional engineered material or 3D layer  19 . 
   In one illustrative embodiment, 3D layer  19  includes a fiber network formed of a woven, knitted, or non-woven spacer fabric which is soft and flexible and/or comprises thermoplastic fibers or monofilaments. One example of such a material is manufactured by SpaceNet, Inc. of Monroe, N.C. In one embodiment, the three-dimensional material is a breathable monofilament polyester mesh fabric that is formed into various three-dimensional patterns after weaving, manufactured by SpaceNet, Inc. In general, the spacer fabric is stretchable in at least two directions. In other embodiments, the 3D material includes a plurality of resilient or compressible projections and depressions. 
   In other embodiments, 3D layer  19  is a three-dimensional fiber network or knit material, such as Tytex manufactured by Tytex Group (Tytex Inc. of Rhode Island, U.S.A.). In still other embodiments, a three-dimensional knit material such as Tytex is used in addition to the SpaceNet or other three-dimensional material. The three dimensional material  19  may include multiple layers such as is described in U.S. patent application Ser. No. 11/119,980, which is incorporated herein by reference. 
   Illustratively, cover  12  is coupled to base  14  at edge  15  through radio-frequency (RF) welding. Alternatively, cover  12  is coupled to base  14  at edge  15  by glue or any substantially air tight sealing known to those skilled in the art. 
   Cover  12  includes a first longitudinal side  2 , a second longitudinal side  4 , a first end  6 , and a second end  8 . The 3D layer is coupled to the overlay at one or more points  13  located along the longitudinal sides  2 ,  4  and/or the ends  6 ,  8 , by stitching or other suitable fastener. Alternatively or in addition, 3D layer  19  is coupled to the overlay at other points, for example, in a quilted configuration. In general, the 3D layer is secured within interior region  18  so as to prevent movement or slippage, for example, as a section of a patient support is articulated or with movement or repositioning of a patient positioned above the overlay  10 . 
   Valve  16  is illustratively positioned at about the center point of first end  6 . Valve  16  may be located anywhere on either end  6 ,  8  or side  2 ,  4  may be desirable for a particular overlay application. In addition, ore than one inlet valve  16  may be provided. 
   In one illustrative embodiment, cover  12  includes a breathable material such as nylon, with micro vents, apertures or holes  22  creating a low air loss surface. In  FIG. 1 , holes  22  are shown in magnified portion  21  of cover  12 . A low air loss surface allows a limited supply of air to escape through cover  12 . In general, low air loss surfaces provide improved support and comfort for a patient and provide a cooling air flow to dry perspiration of the patient. As illustrated, the plurality of holes  22  are configured to allow a limited supply of air to escape cover  12 . 
   In other embodiments, cover  12  is formed from an air permeable or air impermeable material. In certain embodiments, air permeable material is undercoated with a waterproof but vapor permeable material such as urethane. In an alternative embodiment, cover  12  is perforated allowing air to flow from cover  12 . In still other embodiments, cover  12  includes 70d nylon. 
   In one illustrative embodiment, base  14  is made from a breathable material such as 70d nylon combined with a vapor permeable material such as urethane. In a particular embodiment, a urethane coating of less than about ½ millimeter is used. This allows moisture or sweat from the patient to pass or evaporate through the bottom layer  14 . In other embodiments, base  14  is made from plastic, vinyl or any other breathable material. In alternative embodiments, a moisture barrier layer is provided above or below base  14  to capture moisture from the patient allowing base  14  to be made from a non-breathable material. 
   As shown in  FIG. 2 , overlay  10  is configured to be placed on a patient support  24 . In alternative embodiments, overlay  10  is used independently of patient support  24 , or integrated with patient support  24 , such as by sewing, adhesion, snaps, buttons, Velcro®, hook and loop fasteners, or other suitable coupling means. Illustratively, mattress  24  is a foam mattress. In alternative embodiments, mattress  24  is an inflatable bladder filled with air, gel, three dimensional engineered material or other suitable support material, or a combination of such materials. 
   As shown in  FIG. 2 , valve  16  is operably coupled to an air supply  20  at first end  6 . Air supply  20  is configured to force or otherwise provide air to interior region  18 . An illustrative example of valve  16  is provided in U.S. Pat. No. 6,418,579 to Perez et al., which is assigned to the assignee of the present invention and the disclosure of which is expressly incorporated by reference herein. In alternative embodiments, valve  16  can be a quick release valve, a check valve, or any other type of connection between an air supply and an interior region of an overlay or mattress known to those of ordinary skill in the art. 
   An illustrative embodiment of air supply  20  is an adjustable brushless blower or other suitable air supply, for example as provided in U.S. Pat. No. 5,944,494 to Soltani et al., which is assigned to the assignee of the present invention and the disclosure of which is expressly incorporated by reference herein. Additional embodiments of air supply  20  include a fan, a blower, compressor, or any other suitable air supply known to those skilled in the art. In the embodiment of  FIG. 1 , the air enters interior region  18  through inlet valve  16  and exits through the apertures  22 . In the embodiment of  FIG. 2 , an outlet  17  is provided on the end  8  opposite inlet valve  16  for air to be released to the atmosphere. 
     FIG. 3  is a simplified block diagram of a system including an overlay in accordance with the present invention. The illustrated system may be independent of, or integrated with, a bed or mattress control system such as may be used to control features and/or therapies of a mattress or hospital bed. 
   As shown in  FIG. 3 , a controller  30  is electronically coupled to an overly  32 , valve  34 , and air  36  via lines  29 ,  31 ,  33 . Lines  29 ,  31 ,  33  may be copper wire, wireless, or other suitable connection for transmitting electrical signals. Overlay  32  is mechanically coupled to one or more valves  34  by coupler  37 , which are mechanically coupled to one or more air supplies  36  by coupler  35 . Couplers  35 ,  37  may be hoses, plastic tubing, or other suitable couplers for transferring air to the overlay  32 . Additionally, controller  30  may be electrically coupled to an outlet valve such as valve  17  to control the rate at which air escapes the interior region of the overlay. 
   In a simplified arrangement, controller  30  is only coupled to valve  34  and air supply  36  so as to regulate air flow into the overlay  32 . However, in the illustrated embodiment controller  30  is also coupled to the overlay  32 . The overlay  32  is provided with a sensor  38 , which provides information to controller  30 . Controller  30  uses the information to regulate air flow to overlay  32 . 
   In one embodiment, sensor  38  is a humidity detector. If humidity detector  38  detects a humidity level inside the interior region of overlay  32  that is greater than a predetermined threshold amount, the controller  30  will activate the air supply  36  and open the valve  34  to supply air to the overlay. If air is already being supplied to overlay  32 , controller  30  may increase the rate or volume at which air is supplied through valve  34  by air supply  36 . 
   Alternatively or in addition, sensor  38  may include a pressure detector such that the supply of air flowing into overlay  32  may be adjusted (i.e., increased or decreased) based on a pressure detected by the sensor  38 . The internal air pressure within the interior region of the overlay  32  and/or an interface pressure between the top surface  12  of the overlay and a patient positioned thereon may be measured by sensor  38  and monitored by controller  30 . Other conditions that may be sensed by a sensor  38  and monitored by controller  30  as described above include, for example, temperature within the interior region, and weight of a patient positioned on the overlay. 
   In general, controller  30  may be used to turn on or off the flow of air into or out of overlay  30 , and/or to increase or decrease the rate or volume of such air flow, either in response to input received from a sensor  38 , or in response to input provided by a patient or caregiver, e.g. through a switch, button, or user interface  28 . 
   A method of improving air flow is also provided. As shown in  FIG. 2 , overlay  10  is provided and placed on a mattress  24 . Air source  20  provides air that travels through valve  16  and into interior region  18 . Air passes through 3D material  19  and exits overlay  10  through holes  22  in cover  12 . Alternatively, or in addition, air may exit through an outlet  17  as noted above. This allows air to circulate under a patient positioned above the overlay  10 . 3D material  19  provides support for the patient without affecting the interface pressure between the mattress and the patient. The weight of patients will vary and overlay  10  is operable to support either a bariatric or non bariatric patient. 
     FIGS. 4 and 5  illustrate simplified cross sections of an exemplary 3D layer  19 , taken across  4 - 4  and  5 - 5  of  FIG. 1 , respectively. The illustrated 3D layer  19  includes a top portion  40 , a bottom portion  42  and a middle region  44 . Middle region  44  includes a plurality of support fibers  46  and air spaces  50 . 
   Top and bottom portions  40 ,  42  of 3D layer  19  include a cloth or fabric having knit or woven fibers, threads, or strands  48 . The support fibers  48  are arranged in between the top and bottom portions  40 ,  42 . Each fiber  48  has at least a first portion  52  coupled to bottom portion  42  and a second portion  54  coupled to top portion  40 . As shown, the support fibers  46  are substantially vertically oriented between the top and bottom portions  40 ,  42 . Spaces  50  are provided between the fibers  46  to allow air to circulate through the 3D layer  19 . The density of fibers  46  within middle portion  44  determines the level of airflow through the material, as well as the support strength of the material. In general, as the density of fibers  46  increases, the air flow decreases and the support strength increases. In the illustrated embodiments, airflow is generally in the range of about zero to about 19 CFM. 
   The configuration of middle portion  44  and top and bottom portions  40 ,  42  results in a springy, stretchy, resilient material that is capable of providing cushioning, support and is stretchable in longitudinal and lateral directions. 
   Preferably, instructions for the assembly, installation, and/or use of overlay  10  are provided with overlay  10  or otherwise communicated to permit a person or machine to assemble, install and/or use overlay  10 . Such instructions may include a description of any or all portions of overlay  10  and/or any or all of the above-described assembly, installation, and use of overlay  10  or components of overlay  10 . The instructions may be provided on separate papers and/or on the packaging in which overlay  10  is sold or shipped. These instructions may also be provided over the Internet or other communication system. Furthermore, the instructions may be embodied as text, pictures, audio, video, or any other medium or method of communicating instructions known to those of ordinary skill in the art. 
   Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the present invention.