AN ALTERNATING PRESSURE MATTRESS OR CUSHION

Abstract: A foam mattress (2) having open cells is encapsulated in an airtight casing (10), which is connectable with a vacuum source for flat-sucking of the mattress. In partial sub areas (6) of the mattress body (2) the foam material is replaced by more shape stable material bodies (8, 22), the height of which will not be changed substantially by the said flat-sucking, this height being smaller than the height of the mattress body (2) in the free condition thereof, but larger than the height of the mattress body in the flat-sucked condition thereof. When the vacuum is alternatingly applied and relieved a person lying on the mattress will be supported on correspondingly alternating sub areas (2, 8), inasfar as the flat-sucked mattress body will return into its free condition by its own resiliency when the vacuum is relieved. The invention provides for a light and cheap mattress, which is particularly well suited for use in hospitals, because a vacuum installation as required for the operation of the mattress is already available in most hospitals, while a source of a pressurized fluid for actuation of conventional alternating pressure mattresses would require an additional installation for this purpose.

Description: An alternating pressure mattress or cushion, The present invention relates to a mattress or a support cushion of the particular kind which is designed so as to be operable, by suitable control means, to have mutually different surface portions actuated in an alternating manner, such that a lying or sitting person or patient is exposed to a support, which ill a Iternat i ng ly engage different surface portions of the person or patient. Mattresses or cushions of this type are used particularly for patients liable to develop so-called bedsores, which may easily occur if the patient is long-term supported on unchanged surface portions of this or her body, i.e. if the patient cannot readi ly change his position on the bed or couch. However, the known mattresses or cushions of this type are very expensive and complicated, and it is the purpose of the invention to provide a relatively simple and inexpensive, yet effective mattress or cushion for the relevant purpose. The invention even has an ulterior o ject based on the finding that such an alternating body support is highly pleasant also to "non-patients", whereby the discussed type of mattresses and cushions will be extensively usable just when they can be manufactured at low costs as far as both the units and their associated actuation equipment is concerned. The invention is based on the principle that by effecting a change of the pressure in certain area portions of the mattress it is possible to raise and lower the surface of these portions relative other portions, whereby the two groups of surface portions may alternate as operative support areas. According to the invention the mattress is made of a foam material having a suitable carrier capacity and consisting of open cells, this mattress being prepared with suitably located partial areas containing mattress sub elements, which are shielded from the air space associated with the open cells of the foam mattress and which, in a starting position, project upwardly to a level above or underneath the top side of the foam mattress; the surfaces of the foam mattress are covered by an air tight coating forming a casing, which has a connector opening for connect on with a device for changing the air pressure in the foam mattress inside the said casing. It is possible hereby, by changing the pressure in the foam material, to make the top side thereof move upwardly and downwardly between respective levels above and below the top level of the said partial areas, which will remain unaffected by the pressure changes, and already hereby the mattress will be of the discussed type, though of a simple and cheap design. It is a distinctive feature of the invention, however, that the basic element is a foam mattress of full carrying capacity and that the operative pressure change is effected by subjecting the interior of the said surface casing of the mattress to a vacuum, such that the thickness of the ' ' :rmal" mattress wi ll hereby be considerably reduced, whereby the originally counter¬ sunk partial areas will take over the support function. When the vacuum is relieved the foam mattress will return into its original carrying shape or thickness by its own natural resiliency, i.e. by this resiliency it will cause the lying or sitting person to be lifted above the top side of the said partial areas as having formerly carried the person. This function is contrary to the general trend of the development, according to which it has been customary to produce an active lifting of the surface of the mattress by way of an applied pressure, as in an air mattress, whereafter it would be the weight of the l ing or sitting person which would force the top side of the mattress downwardly in response to the internal pressure in the mattress being relieved. This "inverted" principle of the invention offers considerable advantages. Thus, from a practical point of view it is very important that in most hospitals there is already at hand a vacuum system which is accessible at each room or even at each bed, while normally no corresponding pressurized air system is installed. Moreover it is important that it is possible to make use of a type of mattress, viz. consisting of a foam material, which, to the user, is more pleasant to lye on than on a real "air mattress", whereby from a technical/economical point of view this is made possible or favoured thereby that a mattress casing, which should resist only a subpressure in the mattress, but not any overpressure therein, will condition a very simple design, inasfar as the casing may be a simple sheet cover, which is sucked against the surface portions of the mattress unit by the action of the vacuum. Thus, these surface portions should not be prepared to be able to resist any internal overpressure in the mattress material, whereby this material in its entity may be a cheap, homogenous ateriaL having open cells. It has been found that an ordinary mattress materiaL of a sufficient carrier capacity and having open cells, e.g. consisting of Nylon, may be "sucked together" into less than half the natural thickness thereof already by the suction from an ordinary household vacuum cleaner when the mattress is enclosed in a tight sheet casing. The change of the shape of the mattress unit is observed as a reduction of the thickness thereof and only to a small degree as a reduction of the area of the mattress. The said non-changing partial areas of the mattress ma:y, by way of example, consist of blocks of a foam ma¬ terial mounted in holes in or through the foam mattress, and they may be made of" a foam material having closed cells or be otherwise vacuum insulated from the remainder of the foam mattress; alternatively the air tight casing of the foam mattress may cover even the wall surfaces of the holes or recesses in which the foam blocks or corresponding mattress elements are mounted. The invention, which is more precisely defined in the claims, will now be described in more detai l with reference to the drawing, in which:- Fig. 1 is a perspective view of a mattress accord¬ ing to the invention, Figs. 2 and 3 are sectional views thereof, shown in two different conditions. Fig. 4 is a sectional view of a modified mattress according to the invention, while, Figs. 5-7 are plan and top views of another modified embodi ment . The mattress as shown in Fig. 1-3 is made of a coherent mattress body 2 consisting of a soft or resi¬ lient foam material having open cells, e.g. a Nylon foam, and having an intermediate Layer 4 of a strong sheet materiaL or preferably a layer of a relatively resilient foam material having closed cells, e.g. a material known under the trade name "Alveolit". The mattress body 2 is provided with holes 6, in w ch blocks 8 of a suitably carrying materiaL are inserted, Likewise pre- ferabLy made of a foam materiaL. In the initial or na¬ tural condition of the mattress the blocks 8 are present in the holes 6 such that their top surfaces are Located a certain distance, e.g. 5 cm, below the top side of the mattress body 2. The entire mattress body 2 including the walls of the holes 6 is covered or coated by a sheet casing 10, Fig. 2, having a connector mouth portion 12 adapted for connection with a vacuum pipe 14. Alternatively the sheet casing 10 may be constituted by an integral, tight surface Layer shaped by the foaming-up of the mattress materiaL in a mould, in wh ch the intermediate Layer is mounted beforehand. By its foaming up the foam material will be strongly laminated to the intermediate layer when the Latter consists of the said particular foam material. With the use of a mattress material of a usual or sufficient softness and a reasonable thickness of e.g. 130-140 mm the shape of mattress, due to the holes 6, wi ll tend to be unstable in use, but this is what has been found to be counteracted by means of the inter- mediate, relatively unstretchable layer 4, which wi ll extensively stab lize the mattress. When vacuum is applied to the casing 10 air ill be sucked out from the cells in the mattress body 2, but not from the blocks 8, and the result is shown in Fig. 3, from which it appears that the mattress body 2 is sucked thin against the action of its own resiliency, while th ' e blocks 8 substantially maintain their height so as to now project substantially from the top side of the mattress body 2, e.g. projecting upwardly as much as they were formerly (Fig. 2) countersunk in the holes 6. Due to the presence of the intermediate layer 6 the mattress wi ll not noticeably change its area by the thin-sucking thereof. When the vacuum on the casing mouth 12 is relieved and air is allowed to flow into the casing such an in¬ flow will take place because the mattress body 2, by its own resiliency, will expand into its original hi ckness. In the first instance a person lying on the mattress ll be carried by the mattress body 2, viz. on the area portions thereof outside or between the holes 6, while the carrying accordi ng to F g . 3 is taken over by the blocks 8 when vacuum is applied to the casing 10, whereby the carrying pressure is changed to other surface portions of the body of the person. When the vacuum is relieved and the mattress portion 2 gets thicker, the person wi ll be lifted to above the blocks 8 by the se If-resi L i ency of the mattress body 2, until the starting position has been reestablished. It is possible hereby to achieve in a very simple manner that the support pressure on the person can be shifted between the di fferent areas with any desired shifting frequency. In Fig. 3 it is shown by a curved dotted line that the Lying person may suppress the blocks 8 to different heights all according to the Local load on the blocks. The blocks are preferably made of a foam materiaL which is somewhat harder than a con¬ ventional mattress material, e.g. double as hard. Figs. 1-3 are intended to primarily i llustrate the principle of the invention, though by a preferred e bo- diment, inasfar as the mattress may be designed in many other ways. Thus, the casing 10 as a loose sheet may be arranged so as to cover both the top ends and the bottom ends of the holes 6, but not the walls of the holes 6, whereby the blocks 8 should just consist of a foam material having closed cells, such that the blocks are not substantially affected by the vacuum. However, the holes should preferably be through-going as the mattress can then "breathe" through the blocks 8. Instead of circular cylindrical blocks 8 even square blocks or conical blocks could be used, or in¬ stead of separate blocks it will be possible to use coherent structures in or of any suitable pattern. Prin¬ cipally it may be the blocks or the corresponding co¬ herent or continuous structure parts which cooperate effectively with the mouth portion 12, such that the mattress body 2 will have a substantially constant thickness while the thickness or height of the block or structure insert parts may be varied by the pressure differences as applied through the connection to the conduit 14 and associated valve or control equipment. As illustrated in Fig. 4 the mattress member may be shaped with a top side which, in a free condition thereof, shows ra sed area portions 18 and countersunk area portions 20; these portions may be shaped and di¬ stributed in any suitable manner, though here provided in one coherent or unitary mattress member. In the illustrated hatched areas 22 underneath the depressed topside portions 20 the mattress material is made "tight- cellular" in some suitable manner, e.g. by a differen¬ tiated manufacturing process of the mattress member or by injection of a cell sealing or cell infilling sub¬ stance. It wi ll not be very important, of course, whether the areas 22 are entirely similar or regular. It should be mentioned briefly only that the mattress may be operationally sectionally subdi ided such that if desired only one or more subsections there¬ of can be operated. A special possibility will be to design the mattress with an integral head end portion sho ing an outwardly increasing thickness for the for¬ mation of an elevated head pillow suppor; , whereby it will be possible to lower this support as desired by sucking out a portion of the air inside this section of the mattress. It has been found that a mattress body having open cells may be thin-sucked in a reasonably uniform and fast manner already by suction solely from one end of the mattress, and it is even desirable that the changes are not effected particularly fast. Should an increased reaction speed be desired, the mattress member may well be shaped with internal air channels e.g. along the underside thereof, such that the sucking mouth portion 12 communicates with these channels. Figs. 5-7 illustrate an embodiment comprising a mattress body 24, which is not particularly surface treated, but is provided with a deep zig-zag-groove 26, in which is laid down a continuous foam material sausage 28 consisting of a surface sealed foam mate¬ rial having otherwise open cells and having a central core 30 of a substantially non-st retchab le material, e.g. a foam material core having closed cells. The foam sausage 28 is closed at one end and is provided with a vacuum connector stub 30 at the other end. It will be readily understood that this mattress will function as a differential pressure mattress when the air is sucked out from the sausage 28 (Fig. 7) and let into the sausage (Fig. 6), respectively. Optionally the top sides _ of the mattress body and/or the sausage 28 may extend in a welled fashion up and down in the transverse direction of the mattress for avoidance of entirely planar support surface portions. Moreover, the mattress member may be provided with perforations for providing ventilation channels between the top and bottom sides thereof. The mattress is easily designable in such a manner that a complete shift or change between the carr ing portions thereof will be effected by the applied pressure variations, this being desirable for the support of patients liable to develop bedsores. As mentioned, however, it has been found that even for sound people it is very pleasant to make use of such a mattress, and for the achievement of this pleasantness it is not decisive whether the shift between the different carry¬ ing areas is a total shift, when only noticeable varia¬ tions of the support pressure in the different areas are produced. Hereby the mattress may be designed with a considerably reduced thickness, e.g. for mounting topwise on another mattress of a conventional type or on any other suitable support. In this connection it is important that the mattress may well be designed as a cover element for sitting chairs, commonly but not least in connection with means of transportation such as air planes, trains, busses and motor cars, in which a central control unit wi ll be able to control the shifting between the different pressure areas of all the seats of the relevant means of transportation. Optionally the mattresses or the corresponding seat or backrest cushions may be sub- divided in differential pressure areas of or in a pattern which is finer than in patient mattresses, in which a rather coarse pattern (see Figs. 1 and 5) has been found preferable. It should be mentioned that it is known in the art to produce foam material bodies having an airtight surface skin, whereby the entire bodies can be sucked thin, e.g. for showing a reduced volume when being transported. This possibility, of course, may well be uti lized in connection with storing and transportation even of mattresses according to the present invention. It is to be noted that by the alternating thin- sucking of a considerable area portion of a mattress an advantageous cooling effect ill occur, which may compensate for the fact that just this area portion cannot easily be through-vent lated. By the sucking out, e.g. through 3 minutes, the mattress portion as previously heated by the user will automatically under¬ go a cooling, e.g. by some 5 C, and when the vacuum is later relieved the new intake air will normally be of ambient temperature, i.e. the average temperature of the air in the mattress portion wi ll be noticeably lower than under stationary conditions.

Claims: CLA IMS 1. An alternating pressure mattress or cushion of the type which is designed for alternating actuation of mutually separated sub areas for correspondingly alter¬ nating support of a person resting on the mattress, characterized in that a first plurality of partial areas thereof consist of a carrying foam material having open cells and being provided with airtight surfaces so as to form mutually flow connected foam filled sub portions, which, by connection to a vacuum source, are operable to be sucked together into a reduced thickness, while the mattress in a second plurality of partial areas consists of carrying material portions, which are substantially unaffectable by the applied vacuum and the top sides of which are located in a level between the respective surface levels of the first plurality of partial areas in the free and the evacuated conditions thereof, respecti ely. 2. A mattress according to claim 1, characterized in that it consists of a unitary mattress body of a foam material having open cells and being provided with a number of holes, in which carrier block members are inserted, the height of these block members being smaller than the height of the mattress body in the free condition thereof, whilst the block members project above the mattress body in the evacuated condition thereof. 3. A mattress according to claim 2, characterized in that the block members are made so as to be heightwise substantially insensible towards an applied vacuum, and that the entire mattress body including the block members is surrounded by a tight sheet casing, which is connect- able to a vacuum source. 4. A mattress according to claim 1, characterized in that a foam mattress body is provided with upper channel or groove portions for receiving one or more sausages of a foam material having an outer airtight skin and having at Least at one end a connector portion for connection with a device for a Iternati ng Ly applying vacuum and ambient pressure to the foam sausage. 5. A mattress according to claim 4, characterized in that the foam sausage has a core of a materiaL which is difficult to expand or compress lenghtwise, such as a string of a foam materiaL with closed cells. 6. A mattress according to claim 2, characterized in that in the mattress body there is incorporated one or more intermediate layers in the form of a heavy or half- heavy plastic sheet or a layer of an mpermeable foam materi a I. 7. A mattress according to claim 1, characterized in that the airtight surfaces consist of an impermeable foam materi a L . 8. A mattress according to claim 1, characterized in that the carrying material portions which are substan¬ tially unaffectable by the vacuum, are porous or perforated for enabling a ventilation between the top and bottom sides of the mattress.

Inventors: OPHEE JORN, OPHEE, JORN
Applicants: OPHEE JORN, OPHEE, JORN
Application year: 1985
Main classification: A47C27
IPC codes: A47C27, A61G7