Field of the Invention

The present invention concerns an air holding cell for a mattress. More particularly, but not exclusively, this invention concerns a mattress to assist in the prevention of pressure sores, the mattress comprising said air holding cell.

Background of the Invention

In hospitals and other care environments, patients who are bed-bound or spend a long period of time confined to bed can suffer from pressure sores, which are also known as pressure ulcers. These are painful and attending to pressure sores also diverts nurses and carers from other tasks. The cost of attending to pressure sores can also be high causing a strain on healthcare budgets.

Pressure sores develop as a result of external forces on a patient, resulting from direct pressure, shear, and friction, causing stresses and strain on the tissue. This inhibits circulation and may prevent oxygen and other nutrients from reaching the tissue. Common places for pressure sores include bony protuberances, such as the heels, ankles, hips, bottom, shoulders, elbows, back, and back of the head of a patient. Prolonged pressure between these pressure points and a matress may result in red skin which, in time, forms a blister, followed by an open sore. The pressure sore can be painful for a patient, and also destroy or damage the muscle and/or bone under the skin. These may also become infected and cause potentially life-threatening blood poisoning or bone infections.

One way to prevent pressure sores is to reduce or relieve the pressure on vulnerable areas. This may be by moving the patient and changing the patient position. One way in which this can be achieved, without requiring significant nurse or carer time, and without disturbing the patient more than necessary, is by using a special pressure relief mattress.

Some prior art pressure relief mattresses comprise inflatable cells which support the weight of the user. In some prior art arrangements, a motorised pump can be used to inflate and deflate alternate inflatable cells to vary the pressure on the body of the user. In other prior art mattresses, such as that disclosed in WO 2016/016602 Al, a plurality of inflatable cells are connected via a series of one way valves such that a user’s own movement pumps air through the mattress and thereby causes the pressure in the inflatable cells to vary over time. The variation in pressure can help prevent the user developing pressure sores. It is also known to provide the inflatable cells with a foam insert so as to prevent the inflatable cells from completely deflating during use.

It has been found that the prior art inflatable mattresses may fail to provide sufficient support to the body of the user, or particular parts of the body of the user, in the event that the inflatable cells are deflated. This may be the case when the inflatable cells are deflated by a motorised pump as a part of an inflation and deflation cycle, when the user does not move enough to pump air through the inflatable cells of the mattress, when no pumping means are provided, or when pumping means fail, for example.

Other prior art arrangements provide either a passive mattress for use by a patient that is relatively active, or an active mattress for use by a patient at high risk of bed sores. The active mattress may be connected to a pump and the pressure within air cells making up the mattress varied over time. However, should an active patient become less active, and thus vulnerable to pressure sores, or vice versa, then it will become necessary to move the patient to another bed, or swap the mattress the patient is using. Such a process is time consuming and may risk increasing patient discomfort and/or injury during the movement.

The present invention seeks to mitigate the above-mentioned problems.

Alternatively or additionally, the present invention seeks to provide an improved air holding cell for a mattress and/or an improved mattress.

Summary of the Invention

The present invention provides, according to a first aspect, a mattress comprising: a first, at least partially foam-filled, air cell; a second air cell with an inner chamber and an outer chamber, wherein the outer chamber surrounds the inner chamber, and the inner chamber and outer chamber are arranged such that the pressure in the inner chamber can be adjusted independently of the outer chamber, wherein the inner chamber is arranged to be in fluid communication with the first, at least partially foam-filled air cell, and the outer chamber is arranged to be connected to a pump unit.

The inner chamber of the second air cell may be in fluid communication with the first, at least partially foam-filled, air cell via a tube. The tube may include a one way valve, such that air may pass from the first, at least partially foam-filled, air cell to the inner chamber of the second air cell, but not vice versa.

The mattress may be able to operate in a passive mode and an active mode.

In the passive mode, movement of a user lying on the mattress may compress the first, at least partially foam-filled, air cell, such that air is pumped into the inner chamber of the second air cell. The foam within the first air cell acts to support the air cell during patient movement. The foam may be compressed during patient movement, such that under further patient movement, and the reduction in pressure exerted on the first cell, the foam decompresses. The first air cell may comprise an input valve, for example, an input valve open to the atmosphere, and the

decompression of the foam may suck air into the first air cell through the input valve. The input valve may be a one-way valve, such that air may pass into the first air cell through the input valve, but not leave the first air cell through the input valve. In such a way, regular movement of a user may pump air from the first, at least partially foam-filled, air cell, to the second air cell. Pumping of air from the first, at least partially foam-filled air cell, to the inner chamber of the second air cell may temporarily increase the pressure exerted on the part of the user lying on the second air cell. The inner chamber may have an over-pressure release valve, such that the increased pressure within the inner chamber is gradually released to the atmosphere, thereby reducing the pressure exerted on the user by the second air cell. As such, in the passive mode, under the movement of the user of the mattress, gently alternating pressure changes may be experienced by the user. This may be a suitable

arrangement when a user of the mattress is relatively active, and thus at a relatively low risk of pressure sores.

In the active mode, the mattress is connected to a pump unit. Specifically, at least the outer chamber of the second cell is connected to a pump unit. The pump unit is operated to increase the pressure within the outer chamber, thereby increasing the pressure experienced by the part of a user lying on the second air cell. The outer chamber may comprise an over-pressure release valve, such that the increased pressure within the outer chamber is gradually released into the atmosphere, thereby reducing the pressure experienced by the user. The pump unit may be configured to regularly increase the pressure within the outer chamber of the second air cell, thereby providing an active alternating pressure program. The pump unit may also be connected to the first, at least partially foam-filled, air cell. The pump unit may be configured to alternate pressure within the first, at least partially foam-filled air cell in a similar way to that of the second air cell. The active mode may be most suitable for users of the mattress that are not active enough in their movement to pump air through the mattress themselves. Such users are at higher risk of pressure sores developing. The pump may also be used to remove air from any of the air-cells to which the pump is connected, thereby reducing the pressure within those air cells.

The mattress allows a single mattress to be provided which may be used in an active mode or a passive mode. Typically, in the prior art, a mattress will be provided for use in a passive mode, and a different mattress will be provided for use in an active mode. This may require patients to be moved beds, or at least have their mattress changed, in the result of their condition either improving or deteriorating.

The invention allows a single mattress to be used, and the only change required is that the mattress is connected to a pump unit, or if already connected to a pump unit, the pump unit is activated. In addition to the change of mattress mode being much easier and more efficient than changing beds or mattresses, the need to store different types of mattress is eliminated.

The outer chamber of the second air cell may be approximately cylindrical when fully inflated. The inner chamber of the second air cell may be approximately cylindrical when fully inflated. When the outer chamber and inner chamber of the second air cell are both fully inflated, the inner chamber may be located

approximately centrally within the outer chamber, or alternatively located offset to the central axis of the outer chamber. The inner chamber may be peanut shaped in cross- section. The inner chamber may comprise a central seam, running from or close to from one end of the inner chamber to, or close to, the other end of the inner chamber. Such a central seam may provide some additional stiffness or stability to the inner chamber when inflated. The inner chamber may be substantially, or completely foam-free, and/or free of any other material within the inner chamber.

One or both of the first, at least partially foam-filled, air cell, and second air cell may comprise a pliable plastic material. The pliable plastic material may be air impermeable. One or both of the first, at least partially foam-filled, air cell, and second air cell, may comprise Polyurethane film.

The mattress may comprise a first air-holding portion, the first air-holding portion comprising a plurality of at least partially foam-filled air cells, as described with reference to the first, at least partially foam-filled air cell. The mattress may comprise a second air-holding portion, the second air-holding portion comprising a plurality of air cells with an inner chamber and outer chamber, as described with reference to the second air cell. The first air-holding portion may comprise the approximate middle of the mattress, the middle taken in a longitudinal, head to toe, direction. As such, the first air-holding portion may be arranged to support the torso of a user of the mattress. The second air-holding portion may comprise an end portion of the mattress. As such, the second air-holding portion may be arranged to support the heels of a user of the mattress. Each of the plurality of the first, at least partially foam-filled, air cells may be arranged to be connected to a respective one of the second air cells. Where the term connected is used, the skilled person will appreciate that it means the air cells are in fluid communication with each other. For example, the air cells may be connected by a tube through which air can pass. The tube may include or be connected to a one-way valve in order to control the direction of air flow between the air cells. In an alternative embodiment, each of the plurality of the first, at least partially foam-filled, air cells may be arranged to be exclusively connected to one of the second air cells. This air cell may be the lower-most of the second air cells, i.e. the second air cell closest to a longitudinal end of the mattress.

The air cell may be the upper-most of the second air cells, i.e. the second air cell closest to the first, at least partially foam-filled air cells. The plurality of second air cells may be connected to each other, for example in series, with the final of the second air cells comprising an overpressure valve open to the atmosphere. The air may be pumped into the second air cell connected to the plurality of first, at least partially foam-filled air cells by movement of a user of the mattress. The air may then be pumped through the plurality of second air cells by movement of a user of the mattress, either directly on the plurality of second air cells, or on the plurality of first, at least partially foam-filled air cells. The second air cell, or plurality of second air cells may be arranged to be close to, or at, the maximum pressure for that air cell during all the time the mattress is being used. The maximum pressure may be determined by a pressure relief valve associated with the second air cell.

It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.

Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

Figure 1 shows a schematic plan view of a mattress according to a first

embodiment of the invention;

Figure 2 shows a schematic view of an air cell according to the invention;

Figure 3 shows a cross-sectional view of the air cell shown in figure 2;

Figure 4 shows a plan view of the air cell shown in figure 2;

Figure 5 shows a cross-sectional view of a partially foam-filled air cell according to the invention;

Figure 6 shows a schematic plan view of a mattress according to a second

embodiment of the invention; and

Figures 7 and 8 show a cross-sectional and plan view of an alternative air cell according to the invention.

Detailed Description

Figure 1 shows a mattress 10 comprising a first air-holding portion 12 and a second air-holding portion 14. The first air-holding portion 12 is located to align approximately with the torso of a user of the mattress. The second air-holding portion 14 is located to align approximately with the lower legs and feet of a user of the mattress. The first mattress portion 12 is made up of a plurality of at least partially foam-filled air cells 16, 18. The at least partially foam-filled, air cells 16, 18, comprise a pliable, air-impermeable, plastic material surrounding the foam material.

A suitable plastic material is polyurethane film. The second air-holding portion 14 comprises a plurality of air cells, each of the air cells 20, 22, comprising an inner chamber 24 and an outer chamber 26. The air cells 20, 22, comprise a pliable, air- impermeable, plastic material. A suitable plastic material is polyurethane film. As better shown in figure 2, the outer chamber 26 surrounds the inner chamber 24, and the inner chamber and outer chamber are arranged such that the pressure in the inner chamber 24 can be adjusted independently of the outer chamber 26.

The first air-holding portion is in fluid communication with the second air holding portion via an arrangement of tubes and one way valves. The at least partially foam-filled air cell 16 is connected via a tube 28 and a one-way valve 30, to the inner chamber 24 of the air cell 20. The one-way valve 30 is arranged such that air may pass along the tube 28 from the at least partially foam- filled air cell 16 to the inner chamber of the air cell 20, but not vice versa. When a user is lying on the mattress, movement of the torso of the user will compress the at least partially foam-filled air cell 16. This will increase pressure within the at least partially foam-filled air cell and push air along the tube 28, through the one-way valve 30, and into the inner chamber 24 of the air cell 20. The pressure within the inner chamber 24 will increase, until it reaches a point where it exceeds a threshold pressure, at which point air will escape from the inner chamber 24 into the atmosphere via an excess pressure valve 32.

Compression of the inner chamber 24 by a user of the mattress may also result in the pressure within the inner chamber 24 increasing to the threshold value and air escaping via the excess pressure valve 32.

The outer chamber 26 of the air cell 20 is connected to a pump unit 34. The pump unit 34 may be activated to pump air into the outer chamber 26. The air pressure within the outer chamber 26 may increase to a threshold pressure, at which point any further increase in pressure results in air escaping from the outer chamber 26 into the atmosphere via an excess pressure valve 36. Compression of the outer chamber 26 by a user of the mattress may also result in pressure within the outer chamber increasing to the threshold value and air escaping from the excess pressure valve. The pump unit 34 may also be connected to the at least partially foam-filled air cells 16, 18, and be activated to pump air into those chambers to provide an alternating pressure increase/decrease as will be understood by the skilled person. In order to keep the figures clearly understandable, the tubes connecting the pump 34 to the at least partially foam-filled air cells are not shown, but would be easily understood to be present by the skilled person. The pump may, in some

arrangements, also be arranged to suck air out of the air cells, to reduce pressure within those air cells.

The mattress 10 may be configured in a passive mode or active mode. In the passive mode, a user may lie on the mattress 10, such that their torso is approximately aligned with the first mattress portion 12. Movement of the user changes the pressure exerted on the least partially foam-filled air cells 16, 18. An increase in pressure will result in air being pushed from the at least partially foam-filled air cell 16 into the inner chamber 24 of the second air cell 20. The inner chamber 24 of the second air cell is provided substantially full of air at all times, though pressure within the inner chamber 24 may increase and decrease as described. Typically, the user will be resting their feet, and in particular the back of their heels, on the second air cell 20.

The pressure within the inner chamber 24 of the second air cell will increase, prior to decreasing as the threshold pressure for that air cell is exceeded. Therefore, in the passive mode, the movement of the user of the mattress is utilised to vary the pressure experienced by the lower legs and feet of that user. In the passive mode, the outer chamber 26 of the air cells 20, 22, may, if not connected to a pump 34, be open to the atmosphere and substantially uninflated. In the active mode, the outer chamber 26 of the air cells 20, 22, is connected to a pump 34 and the pump is used to inflate the outer chamber. The pressure inside the outer chamber 26 will increase to a threshold level, at which point the air within the outer chamber 26 causes air within the outer chamber 26 to escape through an escape valve 32. The reduction in pressure when a threshold value is met is gradual and regulated by the flow rate of the escape valve 32.

Therefore, the arrangement provides an active increase and decrease in the pressure within the outer chamber 32, which may be most suitable for patients at risk of pressure sores developing. In an alternative embodiment, the pump 34 may be arranged to suck air from the outer chamber 26 of the air cells 20, 22, in addition to pumping air into the outer chambers 26. The inner chamber 24 is, in use, close to or at the maximum pressure inflation at all times. By providing the inner chamber in this state, the proper support being provided to the heels of the mattress is ensured.

The mattress 10 may be easily switched between the passive and active modes, without requiring the user to move from the mattress 10. If the mattress is already connected to the pump unit, all that is required is that the pump is switched on. If the mattress is not connected to a pump unit, all that is required is for a pump unit to be provided, connected to the mattress, and activated. This is much more straightforward and convenient than having to change mattress as in prior art arrangements.

Figures 2, 3, and 4, show the air cell 20, with the inner chamber 24 and outer chamber 26. The overpressure valves 32, 36, are provided connected to inputs into their respective chambers 24, 26. The inputs may include a double headed connector as shown in order that the inputs and outputs into the inner chamber 24 and outer chamber 26 may utilise the same access point, thereby simplifying the constructions of the air cell 20. The inner chamber is located co-axially with the outer chamber 26. The inner chamber 24 and outer chamber 26 are constructed of a Polyurethane film. The inner chamber 24 is maintained in position with respect to the outer chamber 26 by an extension of the film from which the two chambers are made.

Figure 5 shows the at least partially foam-filled air cell 16. A profiled foam portion 40 is surrounded by a Polyurethane envelope 42.

Figure 6 shows a mattress arrangement according to a second aspect of the invention. Where like elements are shared with the mattress described in figure 1, the prefix of“1” has been added to the reference numbers. In the embodiment shown in figure 6, each of the at least partially foam-filled air cells 16, 18, are connected to the same second air cell 122, with a one-way valve 128 arranged such that compression of either or both of the at least partially foam-filled air cells 116, 118, pumps air into the inner chamber 126 of the second air cell 122. The inner chamber 126 of the second air cell 122 is connected, via a tube 140, to the inner chamber 126 of the other second air cell 120. A one-way valve is associated with the tube 140, so that when the air pressure within the inner chamber 126 of the second air cell 122 reaches a threshold value, air is pushed into the inner chamber 126 of the other second air cell 120. The second air cell 120 includes an over pressure valve (not shown) which vents to the atmosphere should the pressure within the inner chamber 126 of the second air cell 120 increase beyond a threshold value. Figures 7 and 8 show a cross-sectional view of a second air cell 220 according to an alternative embodiment of the invention. Where there are similar elements to the embodiment shown in figures 2 to 4, the prefix of“2” has been added to the reference numbers. In the second air cell 220, the inner chamber 224 comprises an initially cylindrical chamber, with an internal weld running along the majority of the length of the inner chamber 224 in a longitudinal direction. As can be seen, this splits the inner chamber in two along most of the length of the inner chamber 224, which increases the width of the inner chamber 224 compared to the height of the inner chamber 224. Such an arrangement may be useful as an alternative to some or all of the second air cells described with reference to figures 1 and 6. The second air cells may be chosen in any combination to provide the optimum comfort and support profile for the users of the mattress. The input and output arrangements of the second air cell 220 is substantially the same as for the second air cell 20, and so will not be described any further, being easily understood by the skilled person.

Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.