Patent Publication Number: US-9849052-B2

Title: Pressure relieving mattress

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application represents the national stage entry of PCT international Application No. PCT/GB2012/051977 filed Aug. 14, 2012, which claims priority to Great Britain Patent Application 1114081.1 filed Aug. 16, 2011, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. 
     This invention relates to pressure relieving mattresses. For many years the main two types of pressure relieving mattresses consisted of a foam mattress with a pressure relieving upper surface or having a pressure relieving overlay, or an inflatable air mattress. Air mattresses enable the patient to be supported in different places at different times by inflating and deflating different portions of the air mattress and their use is important to reduce or prevent bed sores in patients who have to lie relatively immobile in bed. They are, however, expensive, require substantial pumps due to their large air volume and can take a long time to inflate for first use, thereby making any bed switch over slow and problematic. Pressure relieving foam mattresses are used as standard mattresses in most hospital beds but when they become inadequate for a particular patient, for the reason set out above, the change over to an air mattress is time consuming and slow and the bulky foam mattress then has to be stored somewhere in the ward or hospital. 
     For this reason hybrid mattresses have been developed. Most typically they consist of a tray of relatively rigid foam, a pressure relieving overlay and an inflatable inlay located between the overlay and the base of the tray. Accordingly when the variable support of an air mattress is required, a pump simply needs to be attached to the inlets of the inlay and very quickly, with minimum fuss, an ‘air mattress’ function can be achieved. The inlay does not have to provide the full depth of the mattress, as is usual with a typical air mattress, and so its volume is significantly lower, with the result that it can be inflated more quickly. It will be understood that an expensive pump is not needed for each mattress. The ward simply has some available which can be used over the full extent of the ward in accordance with patient&#39;s requirements. Smaller pumps also tend to be less bulky and quieter. Such a mattress is sold by Invacare under the trade mark Soft Form Premier Active. These mattresses have been clinically and commercially very successful but users have reported a tendency for the mattresses to bow near the sides, despite the provision of the firmer side edges of the tray like base. 
     From one aspect the invention consists in a pressure relieving mattress including an elongate support having a base, pressure relieving overlay and an inflatable inlay having a plurality of laterally extending inflatable cells characterised in that at least some of the cells, in at least their un-inflated state, have an inflatable volume which is wider adjacent its ends than in its mid portion. 
     Thus preferably the at least some cells having a narrow mid portion in an un-inflated state but which, when inflated, together define a substantially horizontal support platform. Preferably the un-inflated volumes of at least some cells are in the shape of a bow tie when un-inflated. 
     The Applicants have determined that, somewhat surprisingly, by providing wider ends in the un-inflated state, inflated cells do not tend to bow at their ends but rather, in their inflated state, tend to provide a substantially horizontal support for the patient. This support may commonly not be continuous, because desirably the cells are arranged in two sets consisting of alternate cells and the inlay is inflated on a cyclical basis so that as one set of cells is inflated, the other set is deflating. 
     From another aspect the invention consists in a pressure relieving mattress including an elongate support having a base and pair of spaced longitudinal side walls the base providing a base surface extending between the side walls; a pressure relieving overlay overlying the base surface; and an inflatable inlay extending between the base surface and the overlay and having a plurality of laterally extending inflatable cells supplied by a supply extending longitudinally along the mattress characterised in that the base is recessed to allow the supply to lie below the base surface. 
     Preferably there are two separate supplies for supplying alternate elements or alternate groups of elements and each supply lies in a or the recess. In some embodiments there may be a recess for each supply. 
     In a particularly preferred construction part of each supply lies on the opposite side of the overlay, in which case that part will also lie in a recess. Thus conveniently there are recesses on opposite sides of the base. 
     The location of the supply or supplies in a recess or recesses means that the elements can extend across the full width of the base surface. In former designs the supplies run along the top of the base surface, reducing the available dimensions for the cells and it has been found that, surprisingly, the resultant gaps between the ends of the cells and the side walls of the base contribute to the bowing of the mattress, when the inlay is inflated. 
     In some embodiments the or each element may have an anchor flap for encircling a supply to secure the element. This has at least two advantages. Firstly it removes the need for a separate tie system, as exists on current hybrid mattresses, often leading to additional thickness of the inlay at the centre, and also it provides the possibility of being able to replace individual elements in the case of a puncture or other failure. 
     Thus the anchored flaps may have an associated passage for allowing air to pass from the supply to the element or to allow air to pass from the element to the supply. In any of these cases the mattress may further include ties for securing the or each supply to the support this may be achieved by attaching the ties to selected elements and, in particular their anchor flaps. 
     At least one of the supplies may be made up of modular elements, which may include T portions, connectors and elbow connectors. The modular nature enables various configurations of elements to be made up and allows for easy repair of any part of the supply becomes damaged. An arm of at least some of the T portions may engage in the passage of a respective element. 
     In any of these cases at least some of the cells may be wider adjacent their ends. These at least some cells may have a narrower intermediate portion, which when inflated together defines substantially horizontal support platform. The at least some cells may be in the shape of a bow tie when un-inflated. 
     From another aspect the invention consists in a pressure relieving mattress including a base, an air supply extending along the base and an inflatable element connected to the supply for inflation characterised in that the inflatable element includes an anchor flap for encircling the supply. 
     From yet another embodiment the invention consists in the pressure relieving mattress including a base, an overlay and an inflatable inlay located between the base and the overlay wherein the inflatable portion of the inlay is substantially the same width as the overlay. 
    
    
     
       Although the invention has been defined above it is to be understood it includes any inventive combination of the features set out above or in the following description. The invention may be performed in various ways and specific embodiments will now be described, by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  is a vertical section through a hybrid pressure relieving mattress; 
         FIG. 2  is a vie from above of an inflatable inlay; 
         FIG. 3  is a view from below of the inlay of  FIG. 2 ; 
         FIG. 4  is a side view taken on the arrow I; 
         FIG. 5  is an end view taken along the arrow II in  FIG. 3 ; 
         FIG. 6  is an exploded view taken from one end and the opposite side of  FIG. 2 ; 
         FIG. 7  is an enlarged detail of the portion of  FIG. 2  circled A; 
         FIG. 8  is an enlarged detail of the portion circled B on  FIG. 3 ; 
         FIG. 9  is a view from below of an un-inflated element of the overlay; 
         FIG. 10  is a side view of the element of  FIG. 9 ; 
         FIG. 11  is an end view of the element of  FIG. 9 ; and 
         FIG. 12  is a perspective view of the element of  FIG. 9  from one end and one side. 
     
    
    
     Referring to  FIG. 1 , a hybrid pressure relieving mattress, generally indicated at  10 , includes a tray  11 , having a base  12  with a base surface  13  and side walls  14 ; a pressure relieving overlay  15  and an inflatable inlay  16 . As will be explained in more detail in due course the inflatable inlay  16  has supply pipes,  18 ,  19  and  20 . The base is formed with a first recess  21  and a second recess  22 . The recesses  21 ,  22  run along the length of the base  13  and are dimensioned to receive the pipes  18  and  19  (in the case of recess  21 ) and  20  (in the case of recess  22 ), so that the pipes  18 ,  19  and  20  all lie below the base surface  13 . 
     Aspects of the inlay will now be described with reference to  FIGS. 2 to 12 . The inlay  16  comprises a series of lateral cells  23  which are engaged, at their respective ends, around the supply pipe  20  and the supply pipes  18  and  19 . As can best be seen in  FIGS. 9 and 12 , each element, in its un-inflated state, has ends  24  which are, wider laterally (in respect of the cell) than the intermediate middle portion  25 . 
     Adjacent its respective ends, each cell  23  has a grommet sealed in its under surface. For reasons which will become clear below each cell has one grommet  26   a  which has an open recess at its centre defining a passage into the cell  23  and another grommet  26   b  which is sealed. Adjacent each grommet  26  is an anchor flap  27  which can form in a circle back to the adjacent grommet  26  so that the centre of the grommet  26  is aligned with an opening  28  in the anchor flap. 
     As can best be seen in  FIG. 6  the supply pipes  18 ,  19  and  20  are made up of modular portions which can be interconnected by T or elbow connectors generally indicated at  29 . The respective cells are engaged onto pipes  18  and  19  at one end and pipe  20  at the other end by encircling respective flaps  27  around the pipe or pipes and pushing the grommet down onto the adjacent connector  29 . The cells  23  are arranged so that their grommets  26   a  and  26   b  alternate down a respective side of the inlay  16 . Thus for example in the arrangement shown in  FIG. 6  the left hand grommet of cell one is open ( 26   a ) whereas the left hand grommet ( 26   b ) of cell  2  is closed and so on alternately length of the inlay  16 . The blanked off grommets of cells  1  and  10  are not illustrated in the exploded drawing. 
     In use, a pump (not shown) is connected to pipes  18  and  19  via a CPR release plug  30 , which enables the whole mattress to be deflated extremely quickly in the event that resuscitation needs to take place on the mattress. 
     The pump (not shown) is a two phased pump so that, for example, air can initially be supplied to line  19  pass up elbow connector  29   a  through grommet along the cell  1  down through grommet  26   a  through elbow connector  29   b  into pipe  20 . The air will then pass beneath closed grommet  26   b  in cell  2  to open grommet  26   a  in cell  3 , which will be inflated and the air then passes back into line  18 , bypasses cell  4 , to inflate cell  5  and so on until cell  7  and  9  are inflated. The arrangement is set so that the inflation period is approximately five minutes. The pump (not shown) then switches into its second phase where the odd number cells are opened to atmosphere by the reverse path through which they were inflated and the even cells are inflated using line  18  and a similar path through the even cells. After another five minutes the cycle is begun again. In fact the cells do not fully deflate when open to atmosphere but they cease to be the main support for the patient. Thus the pressure applied to the patient&#39;s body is constantly changing. 
     In previous designs, there had been issues with the inlay “caterpillaring” up the mattress as a result of the alternate inflation and deflation of cells. To overcome this, ties  31  are provided, which attach to the anchor flaps  27 , by means of a respective closed grommet  26   b  and the associated connector, and pass through openings (not shown) in the base  12  to be secured against the underside of the base by respective foot plates  32 . The effect also serves to retain the pipes  18  to  20  in their respective recesses  21 .