The present invention relates to a mattress arrangement to provide responsive support for a patient supported thereon. In particular, the mattress arrangement is intended to minimise pressure points and assist with pressure sore prevention.

It is a problem in hospitals and nursing homes, that patients who are either bed- bound or spend a significant period of time confined to a bed can suffer from painful pressure sores, also known as pressure ulcers. These are painful sores that develop as a result of external forces resulting from direct pressure, shear and friction, causing stresses and strains on the tissue, which inhibit circulation and thereby prevent oxygen and other nutrients reach the tissues. Pressure sores typically occur over bony prominences including the heels, ankles, hips, bottom, shoulders, elbows and back, as well as the back of the head. Prolonged pressure between these pressure points and the mattress result in red skin which forms a blister over time followed by an open sore. These pressure sores are painful for the patient and can destroy the muscle or bone beneath the skin. In extreme circumstances, they can become infected, causing potentially life-threatening blood poisoning or bone infections.

One of the best ways of preventing a pressure sore is to reduce or relieve the pressure on vulnerable areas, for example, by moving around and changing position as much as possible. One way in which this is achieved is through the use of specialist mattresses in hospitals and care-homes. Conventional pressure relief mattresses include specialised foam mattresses comprising a foam base and a specially contoured foam insert on which the body is supported. Although such mattresses are effective at preventing the development of pressure sores, some patients require more assistance to keep moving, and may require an alternative mattress type, such as an inflatable mattress. This type of mattress comprises a series of inflatable sections. Such mattresses may be either permanently inflated or the inflatable cells may be partially or wholly inflated/deflated using motorised pumps. Where a pump is used, each inflatable section is in fluid connection with the pump, which selectively inflates/deflates each inflatable section thereby gently moving the patient supported thereon.

However, there is a need for an alternative pressure relief mattress which more effectively reduces the development of pressure sores and which avoids the need for air pumps, which are both expensive and require regular maintenance. Summary of the Invention

The present invention seeks to address the problems of the prior art.

Accordingly, a first aspect of the present invention provides a mattress arrangement comprising a substantially air-tight support portion, the support portion comprising first and second inter-linked chambers, which are inter-linked so as to allow air to flow therebetween, wherein the first chamber includes a resilient air-retention means, such that, in use, air is able to pass between the first and second inter-linked chambers in dependence upon external pressure applied to the support portion and/or upon decompression of the resilient air-retention means.

In one embodiment, external pressure applied to a chamber causes air flow out of that chamber and into the other inter-linked chamber.

In a further embodiment, removal of external pressure from the first chamber allows decompression of the resilient air-retention means therein, resulting in subsequent air flow into the first chamber from the second chamber.

Preferably, the first and second inter-linked chambers are adjacent one another. The support portion may be further provided with air conduits connecting the interlinked chambers to one-another.

In one embodiment, application of external pressure to a chamber containing an air-retention means results in compression of the resilient air-retention means and air flow out of the chamber and into an adjacent chamber.

The support portion may be further provided with a one-way air valve to permit air ingress into the chambers.

In one embodiment, the mattress arrangement further comprises a plurality of adjacent support portions.

Preferably, the resilient air-retention means in each support portion is identical in one or more of shape, contours, volume and density.

More preferably, at least two of the support portions contain resilient air-retention means which differ in one or more of shape, contour, volume and density.

At least two support portions may contain a differing number of inter-linked chambers.

In a further embodiment, the air-retention means comprises a resilient foam-like material.

The foam like material may comprise one or more of natural sponge, polyurethane foam.

Alternative air-retention means may comprise any suitable resilient plastic or rubber material formed such that on decompression it resumes its original form and draws air into or towards it. For example, an alternative air-retention means may comprise a resilient plastic or rubber material formed with one or more air- retention cavities. This could take the form of a honeycomb structure or potentially a single or multiple chambered bellows-like arrangement. Preferably, the walls of the interlinked chambers comprise a resilient plastic material including, but not limited to, polyurethane and PVC. It is to be appreciate that any other suitable resilient plastics material may be used either as an alternative or in combination One advantage of the mattress arrangement is that it is free of any external pump.

A further aspect of the present invention provides a mattress comprising a substantially planar base mattress defining a mattress arrangement receiving portion; and a mattress arrangement in accordance with any preceding claim.

Preferably, the mattress further comprises a patient movement monitor, the patent movement monitor comprising a pressure detector operable to detect an air pressure, an air conduit extending between the pressure detector and at least one support portion and providing a fluid communication path therebetween, such that the pressure detector is operable to detect an air pressure in the support portion, and to produce a measurement signal indicative of such a detected air pressure, and a display means connected to receive measurement signals from the pressure monitor, and operable to indicate when a fluctuation in air pressure in the support portion is detected by the pressure detector.

The display may be operable to move between a first configuration where detected air pressure remains within a predetermined range and a second configuration where detected air pressure fluctuates outside of the predetermined range. Preferably, the patient movement monitor further comprises time monitoring means operable to measure a predetermined time period.

The patient movement monitor may further comprise alert means to provide notification if no air pressure fluctuation outside of the predetermined range has been detected for the predetermined time period.

A further aspect of the present invention provides a mattress system comprising a mattress according to a preceding aspect of the present invention, further comprising a fabric cover dimensioned to fit over the mattress, the fabric cover comprising a resiliently deformable fabric material having fabric stretch properties, the cover having a length and a width and being resiliently deformable along the length and across the width, wherein the fabric stretch properties of the fabric material vary along the length of the cover.

Preferably, the fabric stretch properties of the fabric material vary along the width of the cover.

In one embodiment, the fabric cover comprises a first woven layer and a second waterproof layer, the two layers being bonded together.

The woven layer preferably has a varied weave such that the stretch properties of the first layer vary along its length and/or width. The waterproof layer preferably has uniform stretch properties along its length and/or width.

The woven layer may comprise, but is not restricted to one or more of cotton, linen, nylon, polyester mix or any other suitable moisture wicking fabric. The water proof layer may comprise a resilient plastic material such as, but not restricted to, one or more of polyurethane and PVC.

In a further embodiment, the cover is dimensioned to cover a mattress, cushion, chair or footstool.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 is a view from above of a first embodiment of a mattress in accordance with the present invention;

Figure 2 is a view of the underside of the embodiment of figure 1 ;

Figure 3 is a cross-sectional view of a support portion of the embodiment of figure 1;

Figure 4A is a cross-sectional view of a further embodiment of a support portion;

Figure 4B is a view from above of the support portion of figure 4A;

Figure 5 illustrates the patient monitoring device display connected to the sacral area support portion;

Figure 6 illustrates a mattress cover for use with the mattress arrangement of figures 1 and 4 A and B; and

Figure 7 is a cross-sectional view of various foam sections. Detailed Description of the Invention

Figure 1 shows an embodiment of a mattress 10 in accordance with the present invention, and figure 2 shows the underside 12 of mattress arrangement 4. Mattress 10 comprises a foam mattress base 2 having a substantially planar base 4 and side borders 6 that extend above planar base 4, thereby creating a recess into which mattress arrangement 4 may be received in use. Mattress arrangement 4 comprises a plurality of support portions 12 provided with inter-linked chambers 14, each of which contains a resilient air-resistant means in the form of a shaped foam section 16, which can be seen in figures 3, 4A and 4B. Foam portion 8 is provided to support the head and neck regions. Figure 2 shows the underside of mattress arrangement 4. Each chamber 14 is provided with support straps 18 which extend around the full circumference of the chamber 14. Straps 18 are then secured to backing support fabric 20, thereby holding the chambers 14 in place relative to one another and providing a sheet of fabric that extends beyond the chambers 14 at each end of mattress arrangement 4, which can be secured in place relative to mattress base 2 by tucking under mattress base 2 in the conventional manner. In figure 2, support straps 18, which are present below the fabric 20, are indicated by dashed lines.

Each foam section 16 is shaped and contoured and of appropriate density to support the part of the patient's body that would rest thereon, during use.

Some examples of the different shapes of foam sections 16 that may be employed are shown in figure 7. However, it is to be appreciated that any suitable shape and contours and foam density could be used as long as it provides the appropriate level of support for the intended location of the foam section 16 within mattress arrangement 4. As can be seen in figures 1 and 2, support portions 12 contain between two and four inter-linked chambers 14. However, it is to be appreciated that the number of chambers 14 provided in each support portion 12 may vary depending on the support requirements of the mattress arrangement 4 and may exceed four inter-linked chambers, where appropriate. For example, the lumbar support portion 12a comprises three chambers 14a, hip support portions 12b each comprise two chambers 14b, leg support portions 12c comprise four chambers 14c and ankle support portions 12d comprise two chambers 14d. The foam in the ankle support portions 12d has greater contouring and a lower density that the foam sections 16 in, for example, the lumbar support portion 12a, as the ankle support portion 12d is not intended to support as large a body weight at the lumber support portion 12a.

Figure 3 is a cross-sectional view of the support portion 12b that supports the sacral area of a patient. Figure 3 shows the air conduit 22 linking chambers 14b within support portion 12b. Air conduit 22 comprises a flexible tube extending along the exterior under-surface 24 of each support portion 12b i.e. the surface 24 of support portion 12b that is in communication with backing support fabric 20. The flexible tube 22 extends through the under-surface 24 of each inter-linked chamber within a support portion 12b, making a seal with exterior surface 24 such that air may flow between each inter-linked chamber 14b in support portion 12b without any air loss to the atmosphere. Flexible tube 22 has a first end 26 which is closed and a second end 28 which is provided with a one way air- flow valve 29 which allows air ingress into chambers 14b, but prevents air loss from chambers 14b via second end 28 of flexible tube 22.

A flexible tube 22 and one-way air-flow valve 29 is provided for each support portion 14 in mattress arrangement 4. The one-way air- flow valve allows the influx of air into the chambers 14 to compensate for any loss of air from the chambers that may occur over time as air is lost through the walls of support portions 12.

Figures 4A and 4B show a further embodiment of a support portion 14b. In this embodiment, rather than foam sections 16 being retained within separate chambers 14b, they are retained within a single chamber 14b but kept separate by virtue of a weld joint 15 extending almost the full length of support portion 12b, leaving a small un-welded channel to permit airflow between the two sections A and B of the support portion 12A. In the embodiment shown in figure 4B, two small channels 23 are provided to permit air flow throughout support portion 14b. However, it is to be appreciated that the size, number and location of the airflow channels may vary from that shown in figure 4B.

In use, a patient supported on mattress 10 will exert pressure on support portions 14, with more pressure being applied at specific pressure points e.g. heels, ankles, hips, bottom, shoulders, elbows and back. Taking sacral support portion 14b as an example, when pressure is applied to support portion 12b, a greater pressure will be exerted on one chamber 14b than the other inter-linked chamber 14b. When this happens, the chamber under the highest pressure will compress, foam section 16 will compress and air will flow from that chamber into the inter-linked chamber 14b via air conduit 22. As the total volume of the support portion 14b remains the same, due to it being a sealed volume, the air within support portion 14b will increase in pressure and inter-linked support portions 14b will become firmer under the weight of the patient support thereon, with the effect that a greater surface area of support portion 14b is supporting the weight bearing surface of the patient support thereon. This has the effect of reducing the pressure through a single pressure point as the weight is more distributed and thus the risk of a pressure sore at that specific pressure point will be significantly reduced, if not eliminated.

Similarly, when the heels of a patient rest on a chamber 12d of support portion 14d, air flows into adjacent interlinked chambers 12d, thereby increasing the pressure with the interlinked chambers which become firmer and rise up to support the lower leg e.g. calf regions of the patient, thereby distributing the weight normally applied through the heels and reducing the pressure through the heels, thus reducing or eliminating the risk of a pressure sore at the heels of the patient. When the pressure on a chamber 14 is alleviated, foam section 16 within that chamber will decompress, thereby drawing air back into the chamber 14 from adjacent inter-linked chambers 14 and, if the patient weight is removed altogether, the air pressure throughout the sealed volume of air in interlinked chambers will equilibrate again. Thus, the foam section is very important as it is required in order to encourage efficient airflow back into the chamber after removal/reduction of the external pressure applied to the chamber during use.

As a patient moves on the mattress 10, the airflow between interlinked chambers 12 will subtly shift the weight of the user, thereby further facilitating the reduction in the risk of pressure sores.

Pressure point mapping has shown that there is reduced pressure at all pressure points using the mattress 10 according to the present invention when compared with conventional foam and inflatable mattresses.

During use, mattress 10 is covered with a fitted fabric cover 60. Fabric cover 60 comprises a waterproof layer bonded to a woven layer. In order to maximise the pressure reduction qualities of mattress 10 it is important that the fabric cover 60 can stretch to accommodate the changes in the shape, contours and size of the interlinked chambers 14 of each support section 12. As mentioned above, the properties of the foam sections 16 vary in dependence upon their position within the mattress arrangement 4 i.e. in dependence upon the expected weight to be supported on the chamber 14 within which it is located. For example, the foam sections 16 in support portions 14d that support the heels of a user are of lower density and greater contoured surface area when compared, for example, with the foam sections 16 in support portions 14b that support the sacral area of a user, during use. This means that the various support portions 12 will exhibit different changes in shape etc. during use. Conventional fabric covers have uniform stretch properties and therefore resist the change in shape etc. of the support portions 12 in use. Therefore, in order to maximise the positive pressure alleviation properties of the mattress 10, it is important that the cover used accommodates the changes that occur throughout the mattress 10 during use.

Figure 7 illustrates the areas where greater stretch properties would be required. In figure 7, A represents the end of the mattress where a user would locate their head and B represents the end of the mattress where a user would locate their feet, during use. Regions 100 (supporting feet/ankles), 110 (supporting hips), 120 (supporting the bottom) and 130 (supporting the back) are the regions within the mattress cover that would require greater stretch properties than elsewhere. This allows the mattress cover to more effectively accommodate the changes in contour of the supporting mattress as the patient is supported thereon and during movement of position of the patient on the mattress itself.

Therefore, fabric cover 60 comprises a resiliently deformable fabric material having fabric stretch properties that vary along the length and width of the fabric. The waterproof layer of fabric cover 60 has uniform stretch properties along its length and also has uniform stretch properties along its width. However, the woven fabric to which the waterproof fabric is bonded exhibits varying stretch properties along its length and varying stretch properties along its width. This is achieved by altering the weave such that a tighter weave is used at places in the fabric cover 60 where less stretch is desired, for example at the region on which the upper back is supported in use; and using a more relaxed weave at regions in the fabric cover 60 where more stretch is desired, for example, at the region on which the sacral area of the patient would be supported in use. In this way, the fabric cover 60 will deform in to correspond with the deformation of the mattress 10 when bearing weight during use, rather than resisting the deformation of the mattress 10 during use.

Where a patient is not capable of movement, for example, they are unconscious or immobile, it is still necessary for nursing staff/carers to move the patient periodically to ensure that they do not remain in the same position for too long as this would encourage the onset of pressure sores. However, it is often not apparent to carers whether a patient is undertaking sufficient movement without assistance to lower the risk of pressure sores, so typically a pump is used to selectively inflate and deflate portions of an inflatable mattress to keep a patient moving, whether or not that patient requires such assistance.

It would therefore be useful to have an indication of the movement of the patient in order to determine their needs with respect to assisted movement. In order to determine whether a patent is movement without assistance, it is possible to modify the support portion 12b, which supports the sacral area of a patient supported thereon. Support portion 12b is shown in figures 3 and 4A and dashed lines shown an extension 25 to flexible tube 22. Extension 25 links support portion 12b to a patient movement monitor 50, as shown in figure 5.

Patient movement monitor 50 comprises a housing 51 provided with an air inlet 53 to which a second end 49 of flexible tube 22 is connected, in use, to make an airtight seal with housing 51. A pressure detector 52 is located within housing 51 and is fluid communication with the airflow through air inlet 53. The monitor 50 is further provided with display means 54 in communication with pressure detector 52 and operable to receive signals from pressure detector 52 and provide an indication relating to the air pressure detected by pressure detector 52.

Display means 54 may provide an indication of the actual pressure detected or if any change in pressure has been detected. Any detection of pressure indicates that there has been a change in the distribution of external pressure applied to the inflatable mattress and therefore that the patient has moved. In the embodiment shown, the patient movement monitor 50 is further provided with a processor 56 operable to detect the passing of a predetermined time period and provide a signal to the display of pressure fluctuation detection and corresponding time of detection. In this way, it is clear at what time patient movement was detected. The combination of interlinked chambers 14b of support portion 12b, flexible tube 22, and pressure detector 52 form a sealed volume of air. In use, a patient supported on mattress 10 will apply pressure through their sacral area to support portion 12b, thereby increasing the pressure in this sealed volume, the pressure reading of which can be detected as a pressure value at pressure detector 52.

Movement of a patient will result in a shifting of their weight, even if only momentary and a change in the pressure through the sealed volume. This changed pressure will be detected at pressure detector 52. Thus any pressure change or fluctuation measured by pressure detector 52 is indicative of movement of the patient supported on mattress 10.

Although aspects of the invention have been described with reference to the embodiment shown in the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiment shown and that various changes and modifications may be effected without further inventive skill and effort.