GB2578928A

GB2578928A - Segmented foam cushion and method

Info

Publication number: GB2578928A
Application number: GB1819212.0A
Authority: GB
Inventors: James Gavin
Original assignee: Helping Hand Co Ledbury Ltd
Current assignee: Helping Hand Co Ledbury Ltd
Priority date: 2018-09-24
Filing date: 2018-11-26
Publication date: 2020-06-03
Also published as: GB2577323B; GB2577323A; GB201815481D0; GB201819212D0

Abstract

Method of adjusting a cushion with segments 14c, 14d, each having a foam core 22c’, 22d’’ and flexible cover 24c’, 24d’’, where a valve 20 permits air into and out of the core 22c’, 22d’’; and involves opening all valves 20, applying pressure to a segment 14d to be adjusted, then either expelling half of the air in the core 22d’’ or limiting expansion of the core 22d’’ to half capacity, and sealing all the valves 20. The pressure may be a user sitting on the cushion. Multiple segments 14c, 14d may have restricted expansion, which may be 30% of capacity. Also disclosed is a foam cushion having segments 14c, 14d on a base 12 where air is selectively allowed into the core 22c’, 22d’’ via passive intake so that the cushion is self inflatable. A secondary wall 26d’’ may be between the cover 24d’’ and core 22d’’ for use when the cover 24d’’ is damaged. Segments 14c, 14d may be fluidly connected.

Description

SEGMENTED FOAM CUSHION AND METHOD

The present invention relates to method of adjusting a segmented foam cushion for mitigating pressure sore formation, and also to a segmented foam cushion for the same.

BACKGROUND TO THE INVENTION

Patients who spend long periods of time sat in one position, whether in hospital or otherwise, are at risk of pressure ulcers forming. Whilst the skin can tolerate a high pressure for short period, or sustained lower pressure over a longer period, spending too much time in one position can cause capillaries in the skin to close up, which may lead to skin necrosis and the subsequent formation of a pressure ulcer (also known as pressure sores or bedsores).

One way that wheelchair users can reduce the risk is to periodically move from side to side to relieve pressure from sitting in the same position, but this has a limited effect. An alternative is to move to a bed and lie down for a while, but this is not a practical option on a day out.

It can take many weeks for a pressure ulcer to completely heal, with more advanced ulcers potentially never fully healing, although the age and general state of health of the patient will also affect the outcome. They are painful at all stages for all patients, and increase the likelihood of infection for the immunocompromised.

Inflatable cushions are available which mitigate this risk by redistributing pressure across a wider area of the skin. Typically, an inflatable cushion includes a number of inflatable chambers which are filled with air using a pump. When filled, a valve is closed to maintain the pressure inside each chamber. The patient can then sit down on the cushion and the air-filled chambers will redistribute pressure on their body more evenly.

However, there are a number of problems with using an inflatable cushion. There is generally a lack of stability for a patient sat on the cushion, because they can easily pitch forwards, backwards or sideways when shifting their weight whilst seated. The typical user of such a cushion is in a weakened state and so finds it harder to balance properly on the cushion, which exacerbates this problem.

It is necessary to use a pump to inflate the cushion so that it is ready for use in a reasonable timeframe, and to force enough pressurised air into the cushion to provide adequate support when the weight of the person is applied. However, using a pump often leads to the cushion being over-inflated when preparing it for use, and so the cushion surface is not as flexible as it needs to be. This increases the risk of a pressure sore forming when a patient is sat on the cushion. Furthermore, the plastic membrane used in an inflatable cushion degrades over time. When the membrane wears out in one section, the cushion must be replaced because it can no longer be inflated properly and continued use would be clinically inappropriate.

It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to a first aspect of the invention, there is provided a method of adjusting a segmented foam cushion for mitigating pressure sore formation, the cushion comprising a plurality of spaced foam segments which each include a foam core, a flexible outer wall around the foam core for sealing the foam core, and a valve or releasable sealing means connected to the foam core for allowing air into and out of the foam core, and the method comprising the steps of a) opening the valves or sealing means to expand the foam segments; b) applying pressure to at least one of the foam segments to i) following step (a), expel at least 50% of the air in the foam core; or ii) during step (a), control or limit expansion of the foam core to only allow intake of up to 50% of the air capacity of the foam core, followed by closing the valve or sealing means in that foam segment; and c) after performing step (a), closing the valve(s) or sealing means in the foam segment(s) not involved in step (b).

Optional features are presented in dependent claims 2 to 5. The first aspect of the invention may include any one or more features presented with respect to the second aspect of the invention.

Providing a partially expanded (or compressed) foam segment alters the way pressure is distributed on a patient's body when sat on the cushion. Limiting expansion of one or more of the segments gives a degree of control over which parts of the body are provided with the most support, and can be used to manage problematic areas (i.e. areas which are at risk of a pressure sore forming, or which already harbour a pressure sore).

Including less air in a segment than it is able to contain at atmospheric pressure thus allows pressure to be distributed to less vulnerable areas of a patient's body. Having the patient sit on and lean on the cushion in step (b) ensures that the pressure distribution on different parts of their body i s optimi sed for that particular patient. This is preferable because the patient can feel what is right for them, and provide feedback or take action accordingly.

The cushion can periodically be adjusted further to provide a new set or configuration of segments which are expanded to various extents (where a set/configuration includes one or more segments), if clinically appropriate. This may involve adjusting the amount of expansion in a particular foam segment. Alternatively, it may involve expanding one or more segment(s) and compressing one or more expanded or partially-expanded foam segments.

It will be appreciated that controlling expansion of the foam core in (b)(ii) includes the options of initially over-expanding the core followed by expulsion of air, or allowing expansion without taking in air corresponding to more than half the capacity of the foam core, or allowing the core to remain compressed.

According to a second aspect of the present invention, there is provided a segmented foam cushion for a seat for mitigating pressure sore formation, the cushion comprising a base and a plurality of foam segments connected to the base, the foam segments being spaced apart from each other on the base, the base restricting freedom of movement for a lower portion of each foam segment, each foam segment including a foam core, a flexible outer wall around the foam core for sealing the foam core, and a valve or releasable sealing means connected to the foam core for allowing air into the foam core, the foam core being configurable between a compressed state for storage and an expanded state for use, wherein when the foam core is in the compressed state the valve or sealing means is openable to allow passive intake of air to expand the foam core in a direction away from the base, the thickness of the foam core in the expanded state being at least two times the thickness of the foam core in the compressed state.

Optional features are presented in dependent claims 7 to 24.

Advantageously, the cushion passively inflates to atmospheric pressure when the valves are opened. There is no issue with over-inflation or under-inflation because there is no need for the patient or carer to pump air into the cushion. The way that the foam segments (or foam cells) are connected to the base restricts the extent to which their lower sections can move, which provides significantly improved front-rear and lateral stability provided to a person sat on the cushion, relative to a conventional air-filled cushion.

Using discrete foam segments provides better stability and support than using empty chambers which are subsequently pumped full of air. Under load during use, the segments are can bear against each other, which helps them to retain their shape and resist distortion to some extent. Each foam core is preferably individually configurable between compressed and expanded states.

Should the top surface of a given foam segment begin to wear out, the cushion can still be used to provide effective support to a patient. This is because the structure of each foam core provides some support, and under load the intact portions of the segment wall will keep air in the foam to some extent. This means that the cushion still provides fairly effective support until a replacement is obtained. Support is provided by the foam filled with air at atmospheric pressure.

The term foam' is used interchangeably with the term 'sponge' in this specification. The foam is preferably selected to have properties which make the foam resilient and light, which enables the foam to push the flexible outer wall away from the base as air is drawn in (when the valve or seal is opened).

The flexible outer wall of the foam segment may be considered to be an envelope or membrane which is impermeable to air.

The foam core may be adapted or constructed to allow ingress of a predetermined volume of air when transitioning from the compressed state to the expanded state. The density and/or porosity of the foam may be selected according to the volume of air which should be taken in to put the foam into the expanded state. This allows the level of support provided by the cushion to be tailored to the needs of a particular patient.

The volume of air contained in each foam core at atmospheric pressure in the expanded state may be substantially less than the total volume within each foam segment.

The thickness of the foam core in the expanded state may be at least three times the thickness of the foam core in the compressed state. The thickness of the foam core in the expanded state may be at least five times the thickness of the foam core in the compressed state. This allows the cushion to be provided in a significantly smaller volume for transport and storage, without comprising the level of support and comfort provided during use.

Four foam segments may be provided in a square or rectangular arrangement. This makes it is easier to remain seated upright on the cushion. This is because using four foam segments provides optimal stability for minimising pitch forwards, backwards and sideways, whilst keeping the cushion reasonably lightweight. In other words, using four segments is the preferred compromise between the volume of air required to inflate the cushion and the stability provided by the cushion.

The thickness of each foam core in the expanded state may be substantially the same as the thickness of the other foam cores when expanded. This provides a substantially even or surface for sitting on, because the surfaces of each foam segment are all at the same level.

Alternatively, the thickness of one or more foam cores may be different to the thickness of some or all of the other foam cores. Having the foam cores at different thicknesses may be preferred in some scenarios to alleviate pressure on one part of the body, or to redistribute pressure differently according to the needs of a particular patient or for a particular treatment regimen.

Each foam segment may extend to one side of the plane of the base. Each valve or sealing means may be on or extend to the other side of the plane of the base This allows the valves or sealing means to be opened with the cushion one way up, and then flipped over for use once the foam segments have expanded.

Each valve or sealing means may be connected to the foam core through the base. This keeps the valves out of the way for comfort, so that they are not sat on or positioned where a patient's legs will be during use. This also avoids the valves being accidentally opened during use, and is more aesthetically pleasing.

The or each valve or sealing means may be positioned at or near an edge of the base. The or each valve or sealing means may be positioned at or near a corner of the foam segment. This means that it is easier to compress each foam segment for storage because the air can be directed to an edge or corner of the segment.

A secondary wall or envelope may be provided between the flexible outer wall and the foam core. If the outermost wall becomes worn, the cushion can continue to be used because the secondary wall keeps the foam core isolated from the atmosphere (except via the valve). This allows time for the cushion to be repaired or a replacement obtained.

The or each foam segment may be cuboidal. Edges of the foam segments may be rounded.

One or more of the foam segments may include a concave area on an upper surface. Two adjacent foam segments may each include concave areas on their upper surfaces. Providing depressions on the foam segments helps to relieve or better distribute pressure on the ischial tuberosities and trochanters during use.

In some versions of the cushion, discrete foam segments which are isolated from each other are provided, and air cannot pass directly between the segments. In other versions of the cushion, the foam segments may be fluidly connected to each other for allowing air to pass from one foam segment to another foam segment. Valves may connect one foam segment to one or more other foam segments to control how air flows between the segments during use. For example, valves may control whether air can pass from rear segments to front segments, or vice versa. Valves may control whether air can pass from segments on one side of the cushion to segments on the other side. This may be used to provide a degree of control or input to the posture of a patient sat on the device.

Valves may be provided between diagonally adjacent foam segments for similar reasons.

One or more of the foam segments may be provided in a partially expanded (or partially compressed) state. This may be achieved by controlling or limiting initial expansion of the foam core, or by fully expanding the foam core and subsequently compressing it to expel a portion of the air contained therein. Each partially-expanded foam segment may include a volume of air which is up to 50%, or preferably up to 30%, of the air capacity of that foam segment at atmospheric pressure. In other words, a reduced volume of air is maintained in the foam segment. This provides an asymmetric distribution of pressure during use.

This can be used to selectively protect certain areas of the body which may be at increased risk of pressure sore formation. In other words, partially expanding or inflating one or more of the segments gives a degree of control over which parts of the body are provided with the most support, and can be used to manage problematic areas (i.e. areas which are at risk of a pressure sore forming, or which already harbour a pressure sore).

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a perspective view of a top side of a segmented foam cushion according to the present invention, shown in an expanded state for use; Figure 2 shows a perspective view of a bottom side of the segmented foam cushion of Figure 1; Figure 3 shows a side cross-sectional view of the segmented foam cushion of Figure 1 in a compressed state; Figure 4 shows a side cross-sectional view of the segmented foam cushion of Figure 1 in the expanded state; and Figure 5 shows a side cross-sectional view of the segmented foam cushion of Figure 1 with one foam segment in a partially expanded state.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figures 1 to 4, a segmented foam cushion is indicated generally at 10. The cushion is shown in an expanded (or inflated) state. The cushion 10 includes a base 12, indicated generally at 12, and four foam segments or cells 14a, 14b, 14c, 14d. In this embodiment, the foam segments are 14a-d discrete from each other. In other words, the foam segments are not directly connected together.

Each foam segment 14a-d is roughly cuboidal in shape. The foam segments 14a-d are provided in a square arrangement in this embodiment. Two of the segments 14c, 14b include circular areas 16 on their top surfaces. The circular areas 16 are provided to better distribute pressure on the buttocks when the cushion is sat on.

The base 12 includes portions or strips 18 of material between adjacent segments 14a-d, which provide spaces 19 between the segments 14a-d. Each foam segment 14a-d is securely connected or bonded to its section of the base. This restricts the movement of a lower region proximal to the base 12 (indicated generally at A, see Figure 4) of that segment, but allows an upper or distal region (indicated generally at B, see Figure 4) of that segment a greater degree of freedom of movement when load is applied.

Each foam segment 14a-d includes a valve 20. Each valve 20 includes a cap 20a and a conduit 20b which leads into the foam segment. The valves 20 for two of the foam segments 14a, 14b are located towards a middle of the edge of the base 12. The valves 20 for the other two of the foam segments 14c, 14d are located towards corners of the base 12. In each case, the valves 20 are located in a corner of the respective base surface of the respective foam segment 14a-d.

Referring to Figures 3 and 4, each foam segment 14a-d includes a foam core. Foam cores 22c, 22d are only illustrated for two of the foam segments 14c, 14d, but it will be appreciated that equivalent foam cores are provided for the other two segments 14a, 14b. Each foam core 22c, 22d is made of CMIHR (Combustion Modified High Resilient) foam in this embodiment. The foam fill has a density of 30kWml and a hardness of 80N in this embodiment. Other foams may be prescribed for use according to patient needs.

Each foam segment 14a-d also includes a flexible outer wall or envelope around its foam core. Flexible outer walls 24c, 24d are only illustrated for two of the foam segments 14c, 14d, but it will be appreciated that equivalent flexible outer walls are provided for the other two segments 14a, 14b. The flexible outer walls 24c, 24d are made of plastic or fabric. The base 12 is also made of plastic or fabric.

A secondary wall or envelope is provided between the flexible outer wall and the foam core of each foam segment 14a-d. As for the flexible outer walls, secondary walls 26c, 26d are only illustrated for two of the foam segments 14c, 14d, but it will be appreciated that equivalent secondary walls are provided for the other two segments 14a, 14b.

When the cushion 10 is in a compressed configuration, the foam cores 22c, 22d have a greatly reduced depth and the flexible outer walls 24c, 24d are loose (see Figure 3). The depth of each foam segment 14a-d in the compressed state (see Figure 3) is less than 10mm, which is useful for minimising the cushion volume for transport or storage.

To use the cushion, the valves 20 are opened. The foam cores 22c, 22d then passively absorb air from the atmosphere and expand in a direction away from the plane of the base 12 to the state shown in Figure 4.

When the cushion 10 is in an expanded configuration, the foam cores 22c, 22d flexible outer walls 24c', 24d' are provided at their usual length (see Figure 4). The flexible outer walls 22c', 24d' may be held slightly taut, or may be neither loose nor taut (so there is negligible stress/strain on the wall when the cushion is not in use). The secondary walls 26c, 26d may be constructed similarly to the flexible outer walls 24c, 24d and so behave similarly.

The depth of each foam segment 14a-d is about 50mm in the expanded state. This means that the foam increases in depth by a factor greater than 5x when the valve 20 is opened and a predetermined volume of air is absorbed. The characteristics of the foam are selected according to the amount of air that is clinically determined to be appropriate for the level of support required. In Figure 4, one of the valves 20 is illustrated as being open whilst the other valve 20 is shut. After expanding the foam cores but before use, the valves are all closed to keep the predetermined volume of air contained within the foam segments 14a-d, to maintain the prescribed level of support when the cushion is sat on by a person.

In some embodiments, one or more of the foam cores are partially compressed (or limited in their initial expansion from a compressed state) before closing the associated valve. Figure 5 is provided to illustrate this, showing the partially-expanded foam core 22d", partially-expanded outer wall 24d", and partially-expanded secondary wall 26d". The valve will, once closed, trap a reduced volume of air inside the foam segment. This will correspond to about 50% of the air capacity of the foam core. It customises the way pressure is distributed on the body of a given patient.

To provide the cushion like this, the patient can sit on it and transfer their weight to a part of their body by leaning in a particular direction, or pressure can be applied by other means. This compresses one or more foam segment(s), and the valves can be closed to maintain the segments in a partially compressed (or partially expanded) state.

Thus, during use, reduced support is provided to one area, and relatively greater support is provided to another part. This can be used to 'shield' or preferentially protect certain areas of the body from developing a pressure sore.

To compress the cushion 10 for storage, the valves 20 are opened and each foam segment 14a-d is compressed in turn from the section furthest from its valve 20 towards that valve 20 for forcing air out of the foam core and valve 20, and the valve 20 then closed.

Other embodiments are contemplated within the scope of the claims. For example, the foam segments may be interconnected to allow air to be redistributed between segments. Inter-segment valves may be used to control the direction of flow between segments. In some embodiments, there may be fewer valves 20 than foam segments, as opening one valve could allow all of the foam segments to absorb air, if a suitable network of inter-segment valves is provided. In some embodiments, there may be more than or less than four foam cells. One or more seals may be removable to inflate the cushion. The foam cells may be different shapes to improve or customise the level of support provided.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS1. A method of adjusting a segmented foam cushion for mitigating pressure sore formation, the cushion comprising a plurality of spaced foam segments which each include a foam core, a flexible outer wall around the foam core for sealing the foam core, and a valve or releasable sealing means connected to the foam core for allowing air into and out of the foam core, and the method comprising the steps of: a) opening the valves or sealing means for expanding the foam segments; b) applying pressure to at least one of the foam segments to i) following step (a), expel at least 50% of the air in the foam core; or ii) during step (a), limit expansion of the foam core to only allow intake of up to 50% of the air capacity of the foam core, followed by closing the valve or sealing means in that foam segment; and c) after performing step (a), closing the valve(s) or sealing means in the foam segment(s) not involved in step (b).
2. A method of preparing a segmented foam cushion for use as claimed in claim 1, in which step (b) is performed for two foam segments.
3. A method of preparing a segmented foam cushion for use as claimed in claim 1 or claim 2, in which at least 70% of the air in the foam core is expelled, or intake of air is limited to up to 30% of the air capacity of the foam core.
4. A method of preparing a segmented foam cushion for use as claimed in any of claims 1 to 3, in which pressure is applied in step (b) by having a person sit on the cushion and lean onto the at least one foam segment.
5. A method of preparing a segmented foam cushion for use as claimed in any preceding claim, in which steps (a) to (c) are repeated after a period of time to provide the cushion with a different configuration of one or more partially expanded foam segments.
6. A segmented foam cushion for a seat for mitigating pressure sore formation, the cushion comprising a base and a plurality of foam segments connected to the base, the foam segments being spaced apart from each other on the base, the base restricting freedom of movement for a lower portion of each foam segment, each foam segment including a foam core, a flexible outer wall around the foam core for sealing the foam core, and a valve or releasable sealing means connected to the foam core for allowing air into the foam core, the foam core being configurable between a compressed state for storage and an expanded state for use, in which, when the foam core is in the compressed state, the valve or sealing means is openable to allow passive intake of air to expand the foam core in a direction away from the base, the thickness of the foam core in the expanded state being at least two times the thickness of the foam core in the compressed state.
7. A segmented foam cushion as claimed in claim 6, in which one or more of the foam segments are provided in a partially expanded state.
8. A segmented foam cushion as claimed in claim 7, in which each foam segment which is in a partially expanded state includes a volume of air which is up to 50% of the air capacity of the foam segment at atmospheric pressure.
9. A segmented foam cushion as claimed in claim 7, in which each foam segment which is in a partially expanded state includes a volume of air which is up to 30% of the air capacity of the foam segment at atmospheric pressure.
10. A segmented foam cushion as claimed in any of claims 6 to 9, in which the foam core is adapted to allow ingress of a predetermined volume of air when transitioning from the compressed state to the expanded state.
11. A segmented foam cushion as claimed in claim 10, in which the volume of air contained in each foam core at atmospheric pressure in the expanded state is substantially less than the total volume within each foam segment.
12. A segmented foam cushion as claimed in any of claims 6 to 11, in which the thickness of the foam core in the expanded state is at least three times the thickness of the foam core in the compressed state.
13. A segmented foam cushion as claimed in any of claims 6 to 12, in which the thickness of the foam core in the expanded state is at least five times the thickness of the foam core in the compressed state.
14. A segmented foam cushion as claimed in any of claims 6 to 13, in which there are four foam segments provided in a square or rectangular arrangement.
15. A segmented foam cushion as claimed in any of claims 6 to 14, in which the thickness of each foam core in the expanded state is substantially the same as the thickness of the other foam cores when expanded.
16. A segmented foam cushion as claimed in any of claims 6 to 15, in which each foam segment extends to one side of the plane of the base, and each valve or sealing means is on the other side of the plane of the base.
17. A segmented foam cushion as claimed in any of claims 6 to 16, in which each valve is connected to the foam core through the base.
18. A segmented foam cushion as claimed in any of claims 6 to 17, in which the or each valve or sealing means is positioned at or near an edge of the base.
19. A segmented foam cushion as claimed in any of claims 6 to 18, in which the or each valve or sealing means is positioned at or near a corner of the foam segment.
20. A segmented foam cushion as claimed in any of claims 6 to 19, in which a secondary wall is provided between the flexible outer wall and the foam core.
21. A segmented foam cushion as claimed in any of claims 6 to 20, in which the or each foam segment is substantially cuboidal.
22. A segmented foam cushion as claimed in any of claims 6 to 21, in which one or more of the foam segments includes a concave area on an upper surface.
23. A segmented foam cushion as claimed in claim 22, in which two adjacent foam segments each include concave areas on their upper surfaces.
24. A segmented foam cushion as claimed in any of claims 6 to 23, in which the foam segments are fluidly connected to each other for allowing air to pass from one foam segment to another foam segment.