EP3113745B1

EP3113745B1 - Heel protection mattress

Info

Publication number: EP3113745B1
Application number: EP15706284.5A
Authority: EP
Inventors: Michael Hutson
Original assignee: Rober Ltd
Current assignee: Rober Ltd
Priority date: 2014-03-03
Filing date: 2015-02-20
Publication date: 2019-09-25
Anticipated expiration: 2035-02-20
Also published as: GB201403707D0; DK3113745T3; WO2015132560A1; GB2523754A; ES2750076T3; GB2523754B; EP3113745A1

Description

This invention relates to an alternating pressure mattress for preventing pressure ulcers, particularly around the heel region of a patient's limb.

BACKGROUND

Bed sores, or pressure ulcers, are likely to occur when a patient is bed ridden for a long period of time, causing parts of the body that are in contact with the mattress to be constantly subjected to pressure. This results in obstructed blood flow, which can damage the affected tissue and ultimately leads to bed sores. The reduced blood flow is especially severe in areas of skin near a protruding bone such as the heel or the hip, and accordingly bed sores are more likely to develop at these locations. Furthermore, the unobstructed blood supply to the heel is relatively poor compared to the rest of the body. The heel is therefore especially prone to bed sores. Furthermore, for the same reasons of poor blood supply in these regions, bedsores on the heel and similar areas are slow to heal.
In hospitals, patients who are deemed to be at risk of developing a bed sore are generally provided with an alternating pressure mattress having a plurality of inflatable cells which are cyclically inflated and deflated.
When cells are deflated the tissue that was supported by the deflated cells is provided with pressure relief. However, the degree of pressure relief provided depends on the extent to which the cells are deflated. For a relatively low risk patient a mattress may be provided in which the cells simply have a valve opened to allow the pressure therein to gradually reduce towards atmospheric pressure. In this event the pressure will not actually reach atmospheric pressure because the open valve still provides a resistance to the air escaping, so air is only removed by the pressure caused by the patient's weight, which is largely supported by the inflated cells once the pressure in the deflated cells has reduced. Therefore, there is a small residual pressure between the patient and the deflated cells. It is undesirable to provide a valve that would allow the pressure in the cell to reduce rapidly to atmospheric pressure because this would "jerk" the patient. Consequently, using a small valve that allows controlled deflation means that deflating cells do not reach atmospheric pressure in the time available. Such a small valve therefore does not provide complete pressure relief.
For patients who face a higher risk of developing a bed sore a mattress may be provided which actively pumps the air out of the deflated cells, ensuring that no residual pressure is applied by the deflated cells. Completely evacuating the air out of the cells makes the mattress more effective in preventing bed sores. By using active pumping a small valve can be used so that initial evacuation is not sudden but, by virtue of the pump, the rate of evacuation remains substantially the same so that complete evacuation does occur, over a relatively short period of time, without the initial sudden rush that would otherwise potentially disturb a patient sleeping on the mattress.
If the air is actively evacuated from the deflated cells it is possible that part of the patient will come into contact with the bottom surface of the mattress. Potentially, this will be uncomfortable, and will cause pressure to be applied to the area in contact with the lower surface of the mattress. One option to avoid this disadvantage is to increase the height of the cells in mattresses providing active evacuation, by making the cells generally elliptical in cross section, with the long axis arranged vertically when the mattress is in use.
Active evacuation of air from mattress cells is effective in providing total pressure relief. However, it also increases the cost of the mattress, as a more powerful pump has to be provided to fill the larger cells, and the pump has to both fill and evacuate the cells. Furthermore, if the patient faces a relatively low risk of developing a pressure ulcer it may be advantageous to provide a residual pressure between the patient and the deflated cells, as this reduces the pressure between the patient and the inflated cells, which may be more comfortable for the patient. Mattresses providing active evacuation are therefore typically reserved for patients who face an especially high risk of developing a bed sore. US2006/026767 discloses a mattress system for a hospital bed including a mattress and a control system. The mattress system may include a mattress including a core bladder, a width bladder and a vacuum device to apply a vacuum to the width bladder. The mattress of US2006/026767 is adapted to support a heavy or large patient, including a bariatric or obese patient.
The present invention aims to provide a low-cost mattress that provides complete pressure relief to areas of tissue that face a particularly high risk of developing a bed sore.

BRIEF SUMMARY OF THE DISCLOSURE

The invention provides a mattress system as defined in claims 1 to 6.
In an embodiment the mattress may further comprise longitudinal edge cells extending along longitudinal edges of the mattress.
In an embodiment the mattress may further comprise at least one additional cell near said second end of the mattress that is configured to remain inflated while said first, second, third and fourth groups of cells are cyclically inflated and deflated, whereby a patient on the mattress may be provided with constant support of their head when lying on said at least one additional cell.
In an embodiment the system may further comprise a quick release mechanism configured to permit rapid deflation of all of the cells.
In another embodiment the quick release mechanism may be configured to fully deflate the cells within 30 seconds of being activated, preferably within 15 seconds of being activated. In another embodiment the control unit may be configured to cyclically: deflate mattress cells attached to said first and third connectors; inflate mattress cells attached to said first and third connectors; deflate mattress cells attached to said second and fourth connectors; and inflate mattress cells attached to said second and fourth connectors.
In a further embodiment the pump unit may further comprise a fifth connector, wherein said control unit is configured to maintain cells attached to said fifth connector constantly inflated whilst cyclically inflating and deflating the cells attached to said first, second, third and fourth connectors.
In another embodiment the pump unit may further comprise a pressure sensor disposed between said first or second compressor and said connectors.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a prior art alternating pressure mattress for preventing bed sores;
Figure 2 shows a graph of the pressure within a cell against time for different methods of deflation;
Figure 3 shows a cross section of an alternating pressure mattress for preventing bed sores in an embodiment of the present invention;
Figure 4 shows an exemplary air circuit diagram for an alternating pressure mattress in an embodiment of the present invention; and
Figure 5 shows a pump unit in an embodiment of the present invention.

DETAILED DESCRIPTION

Figure 1 shows a prior art alternating pressure mattress configured to prevent or treat pressure ulcers by cyclically reducing the pressure applied to different areas of the body of a patient sleeping on the mattress. The mattress comprises a plurality of inflatable cells arranged perpendicular to the longitudinal axis A of the mattress (only eight being shown). The cells are divided into at least two groups of alternately disposed cells, which groups of cells are configured to be cyclically inflated and deflated in a predetermined cycle that ensures that at least one group of cells is inflated at any given time on which the patient is supported. For a typical mattress between 16 and 24 cells will be provided, and the cells will be deflated using either a "two cell cycle" or a "three cell cycle", which means that there are two or three groups respectively of cells. If a two cell cycle is used then the cells may be divided into two groups, with adjacent cells in different groups. Alternatively, a "three cell cycle" may be used, and in that case the cells are divided into three groups, for example a first group comprising cells 2₁, 2₄ and 2₇, a second group comprising cells 2₂, 2₅ and 2₈ and a third group comprising 2₃ and 2₆. In either case the groups of cells are cyclically inflated and deflated in a cycle that ensures that at least one group of cells is inflated at any given time.
Although not shown in Figure 1, prior art mattresses also include at least one compressor for inflating the cells and a controller for selecting which cells are to be inflated or deflated. The controller may be configured to open valves to deflate selected cells at predetermined time intervals, and to actuate the pump and direct the airflow to selected cells to inflate them at predetermined time intervals.
It is known to provide mattresses similar to the one shown in Figure 1 in which the air in the cells is vented to atmospheric pressure when the cells are deflated. Venting occurs through the natural resilience of the material of the cells. However, it also provides a small residual pressure between the patient and the deflated cells. A representation of the reduction in pressure P against time T for cells that are vented to atmospheric pressure is shown by pressure profile 5 in Figure 2. Pressure initially decreases rapidly from inflated pressure P_MAX. However, as the cell deflates the pressure gradient over the valve decreases, causing the rate of deflation to reduce so that the pressure never reaches atmospheric pressure, P_ATM and complete pressure relief is not provided.
It would clearly be possible to allow the pressure within a mattress cell to quickly reduce to atmospheric pressure without providing active deflation, simply by providing a valve with such a large flow area that the valve provides little or no resistance to air escaping. However, this is undesirable because the rapid decrease in pressure, as shown be pressure profile 4 in Figure 2 would "jerk" the patient. Consequently, using a small valve that allows controlled deflation means that deflating cells might never reach atmospheric pressure and provide complete pressure relief, as shown by pressure profile 5 in Figure 2.
It is also known to provide mattresses similar to the one shown in Figure 1 in which the air in the cells is actively pumped out of the cells when they are deflated. This ensures that no residual pressure remains between the deflated cells and the patient. A representation of the change in pressure P against time T for cells that are actively vented to atmospheric pressure is shown by pressure profile 6 in Figure 2. It is to be noted that the initial rate of deflation is slower than that shown in profile 4, so that there is no sudden loss of support for the patient and yet ultimately there is complete pressure relief. However, because the rate of deflation is substantially constant, complete pressure relief is provided.
The cells 2 in Figure 1 have a generally circular cross section. This is typically the case for mattresses in which the cells are vented to atmosphere as illustrated by pressure profile 5 when they are deflated. These mattresses represent the lowest cost type of mattress. However, for mattresses in which the air is actively pumped out of the cells as illustrated by pressure profile 6 it is generally necessary to elongate the cells so that they have a generally elliptical cross section, with the major axis of the ellipse arranged so that it is vertical when the mattress is in use. If the air was actively evacuated from a mattress having cells with a generally circular cross section then it is probable that the patient would come into contact with the bottom surface of the mattress between inflated cells. Potentially, this would be uncomfortable, and wake a sleeping patient when their body contacts the lower surface. Elliptical cells significantly reduce this possibility. However, providing elliptical cells increases the cost of the mattress as the cells are larger and therefore require more material to make. A more powerful pump is also required to fill the cells.
The mattress shown in Figure 1 also includes longitudinally oriented side support cells 3, which help to prevent the patient from accidentally rolling off the mattress. Such side support cells remain continuously inflated when the mattress is in use.
Figure 3 shows a cross section of an alternating pressure mattress in an embodiment of the present invention. The mattress has cells inflated and deflated in a 2 cell cycle and the structure of the mattress is similar to that shown in Figure 1. However, Figure 3 shows cells 2'₂ and 2'₄ deflated to approximately zero pressure, whist cells 2₆, 2₈, 2₁₀ and 2₁₂ all retain some residual pressure. After a predetermined time interval the group of cells that is deflated in Figure 3 will be inflated and the group of cells comprising cells 2'₁, 2'₃, 2₅, 2₇, 2₉, 2₁₁ and 2₁₃ will be deflated. A patient may be disposed on the mattress with their heels located at the first end. In this way the complete deflation of the cells near a first end of the mattress (i.e. cells 2'₁, 2'₂, 2'₃ and 2'₄) advantageously provides total pressure relief to the heel of a patient sleeping on the mattress.
Because cells 2₅ to 2₁₃ are not completely deflated, they provide some residual support to a patient who is unlikely to contact the under surface. Nevertheless, they still benefit from changing pressure on their body so that the risks of bed sores and pressure ulcers developing, in these less-susceptible regions of the body, are still substantially mitigated.
The timing and phasing of the inflation and deflation of the cells at the first end of the mattress (i.e. cells 2'₁, 2'₂, 2'₃ and 2'₄) may be different from the timing and phasing of the inflation and deflation of the other cells (i.e. cells 2₅-2₁₃).
Some cells at a second end of the mattress (not shown) may be in an additional group that remains constantly inflated when the mattress is in use, thereby providing constant support to the patient's head.
Figure 4 shows an exemplary air circuit diagram for an alternating pressure mattress configured to implement a 2 cell cycle in an embodiment of the present invention. Air circuit 10 connects groups of cells A, A', B, B' and C to compressor 11 via filter/sliencer 12, air pipes or tubing 14 and valves 15. The valves 15 and compressor 11 are controlled by a control unit (not shown), which is in communication with pressure sensor 13. Filter/silencer 12 is provided to damp away any high-frequency pulsations that are introduced by compressor 11 that might otherwise cause the patient discomfort.
Groups of cells A' and B' are disposed at a first end of the mattress where the heels of a patient are likely to rest. Group of cells C is disposed at a second end of the mattress opposite said first end and is configured to be continuously inflated when the mattress is in use. Groups of cells A and B are disposed between said first and second ends. Groups of cells A' and B' may each comprise between one and three cells, preferably two cells, and group of cells C may comprise between 1 and 6 cells, for example 4 cells. The remainder of the cells are in group of cells A or B. Cells preferably alternate between group of cells A (or A') and group of cells B (or B') along the length of the mattress. Referring to Figure 3, group of cells A' may comprise cells 2'₁ and 2'₃, group of cells B' may comprise cells 2'₂ and 2'₄, group of cells A may comprise cells 2₅, 2₇, 2₉, 2₁₁ and 2₁₃ and group of cells B may comprise cells 2₆, 2₈, 2₁₀ and 2₁₂. Group of cells C is not shown in Figure 3. Not all cells A, B, A' or B' are shown in the drawings. Typically, there are sixteen to thirty cells forming a mattress, with each cell being between 5 and 15 cm, preferably about 10 cm, in diameter. Furthermore, the cells disposed at the first end of the mattress (i.e. the cells in groups A' and B') may be of a different size to rest of the cells (i.e. the cells in groups A, B and C).
Valves 15 are controlled by the control unit to connect or disconnect cells from different air tubes. For example, valve 15₃ is configured to selectively connect group of cells A' either to air pipe 14, which communicates with the outlet of compressor 11, or air pipe 14', which communicates with the inlet of compressor 11, via valve 15₁.
The control unit is configured to inflate and deflate the cells in a predetermined cycle. For example, the controller may first inflate all of the cells to a predetermined pressure. In this event valve 15₁ connects the inlet of compressor 11 to the ambient atmosphere, valve 15₂ connects the outlet of compressor 11 to air pipe 14, valves 15₃-15₆ connect the respective groups of cells to air pipe 14, and compressor 11 is activated. Once the cells are inflated to a predetermined pressure, which may be measured by pressure sensor 13, compressor 11 is stopped. After a predetermined time delay, either groups of cells A' and A, or B' and B, are deflated. Group of cells A or B is deflated by actuating one of valves 15₅ or 15₆ and connecting the group of cells to air pipe 14", which vents to atmospheric pressure. In this event, these cells deflate gradually so as to minimise disturbance of a patient whose body is supported by them, possibly asleep. On the other hand, group of cells A' or B' is deflated by actuating one of valves 15₃ or 15₄, thereby connecting the group of cells to air pipe 14', which communicates with the inlet of compressor 11 via valve 15₁. Valve 15₂ is then actuated to connect the outlet of compressor 11 to vent and the compressor is then activated to deflate the group of cells. After a predetermined time delay the deflated groups of cells are re-inflated. Group of cells A' or B' may begin re-inflation before group of cells A or B to reduce pressure variations between the cells. After a further predetermined time delay whichever of groups of cells A' and A, or B' and B, was not previously deflated is deflated and then re-inflated in a similar way, and the cycle is repeated.
The valves and the pump are preferably electrically actuated, and the control unit preferably includes a processor disposed on a printed circuit board that is in electrical communication with the valves and the pump. The control unit is preferably provided with software adapted to control the cyclic inflation and deflation of the cells.
Although not shown in the drawing, air circuit 10 preferably further comprises a CPR valve or switch which can be activated to quickly deflate all of the cells in the event that the patient needs CPR. Such a valve or switch is preferably in communication with the control unit, and the control unit is preferably configured to stop the cycle of inflating and deflating the cells once the CPR valve or switch is activated. Alternatively the CPR valve or switch may disconnect the cells from the rest of the air circuit, so that it is impossible for the compressor to re-inflate the cells until the CPR valve or switch is deactivated. The cells are preferably deflated within 30 seconds of the CPR valve or switch being activated, more preferably within 15 seconds of the CPR valve or switch being activated.
In Figure 4 valves 15 are shown at spatially disparate locations. However, it will be understood that this is simply for convenience of illustration, and that the valves may be located anywhere along the length of the air pipes that they connect. Indeed, in one embodiment all of the valves are located in a common manifold which is connected to compressor 11. Such a manifold may advantageously be located within a housing, which housing may also contain the compressor 11 and the control unit. A display and controls may be located on the outer surface of the housing. When the mattress is in use as part of a bed the housing may be disposed at an end of the bed. A housing containing compressor 11, a common valve manifold and a control unit may comprise a replaceable pump unit, which pump unit may be connectable to a mattress comprising a plurality of cells to control the inflation and deflation of said cells.
A pump unit may include compressor 11, filter 12, pressure sensor 13, and at least some of the lengths of air pipes 14, 14', 14" and valves 15 as shown in Figure 4, as well as a control unit for controlling valves 15 and compressor 11. The pump unit further comprises at least first, second, third and fourth connectors for connecting to groups of cells A', B', A and B on a separate alternating pressure mattress, and preferably a fifth connector for connecting to group of cells C. Once such connectors are connected to the respective cells of an alternating pressure mattress the mattress may function as described above.
Figure 5 shows a pump unit 20 in an embodiment of the present invention. Pump unit 20 comprises a housing 26, a control unit 25 and valve manifold 24, first and second compressors 21, 22, a vent 27 and first, second, third and fourth connectors 23₁-23₄, valve manifold 24 being in fluid communication with compressors 21, 22, vent 27 and first to fourth connectors 23₁-23₄. Valve manifold 24 includes at least one valve to independently control fluid connections to each of the first to fourth connectors 23₁-23₄. The valves controlling fluid connections to first and second connectors 23₁, 23₂ are configured to connect each of the connectors to one of the first and second compressors 21, 22, or to disconnect the connector from both compressors and from vent 27. The valves controlling fluid connections to third and fourth connections 23₃, 23₄ are configured to connect those connections either to the first compressor 21 or vent 27, or to disconnect the connectors from both compressors and from vent 27.
Control unit 25 is in electrical communication with the first and second compressors 21, 22 and valve manifold 24, and is configured to control the connections made by the valves in valve manifold 24 and the operation of compressors 21,22. In this way control unit 25 may control the inflation and deflation of mattress cells that are in fluid communication with connectors 23₁-23₄.
Connectors 23₁-23₄ may be connected to different groups of cells within a mattress. For example, connectors 23₁ and 23₂ may be attached to a first and second groups of cells located in a first section of the mattress where a patient's heels are likely to rest, and connectors 23₃ and 23₄ may be attached to third and fourth groups of cells located in a second section of the mattress. When connectors 23₁-23₄ are connected in this way control unit 25 may provide pressure relief to a patient lying on the mattress by controlling the first and second compressors and the valve manifold to cyclically inflate and deflate all of the groups of cells, with the deflation of the first and second groups of cells being performed by actively pumping the air out of the cells using the second compressor 22 and the deflation of the third and fourth groups of cells being performed by venting the cells to atmospheric pressure via vent 27. In this way the patient is provided with total pressure relief in the heel region, but not around the upper body.
Although Figure 5 shows control unit 20 having a first compressor 21 for inflation of the cells and a second compressor 22 for deflation of the cells, it will be understood that a single compressor may be used for both inflation and deflation. In this event one or more valves may be included to selectively connect either the inlet or the outlet of the compressor to valve manifold 24. Furthermore, control unit 20 may also include a filter/silencer disposed between the compressors 21,22 and the connectors 23₁-23₄ to damp away any vibrations or flow pulsations caused by the compressors. A pressure sensor may also be included between the compressors 21,22 and the connectors 23₁-23₄, which pressure sensor preferably communicates with control unit 25 to determine when cells attached to connectors 23₁-23₄ have reached a predetermined pressure, and so inflation is to be stopped.
There is also disclosed a method for the prevention or treatment of bed sores by disposing the patient on an alternating pressure mattress similar to that shown in Figure 3 with the patient's heels located above any of the cells that are configured to be actively deflated (i.e. cells 2₁'-2₄'). Once the patient is disposed on the mattress in this way the cells are cyclically inflated and deflated, with the air in cells 2₁'-2₄' being actively pumped out when the cells are deflated and the air in the other cells being simply vented to atmosphere when the cells are deflated. The cycle in which the cells are inflated and deflated preferably maintains at least half of the cells inflated at any given time, for example by inflating all groups of cells that are deflated before deflating another group of cells.
Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Claims

An alternating pressure mattress system (10) that comprises a first compressor (11);
a mattress (1'), having a plurality of cells (2') lying transversely with respect to a length of the mattress and disposed in side by side relationship along the length of the mattress between first and second ends thereof, the cells being divided into at least four groups of cells, a first and second (A', B') of said groups of cells being located in a first section of the mattress and a third and fourth (A, B) of said groups of cells being located in a second section of the mattress, wherein said first section of said mattress is located at said first end of said mattress,
a pump unit comprising said first compressor (11), first, second, third and fourth connectors (23), a plurality of valves (24) configured to control the flow of air to and from said compressor and through said first, second, third and fourth connectors; and a control unit (25) configured to control said valves and said compressor to cyclically inflate and deflate mattress cells attached to said connectors;
characterised in that said cells attached to said first and second connectors (A', B') are arranged to be deflated by active evacuation of the air from said cells by the pump unit; and
said cells attached to said third and fourth connectors (A, B) are arranged to be deflated by passive allowance of the air in the cells to vent to atmosphere, no active evacuation being arranged, whereby cells attached to said third and fourth connectors provide some residual support to a patient on the mattress when they are deflated.
The system of claim 1, further comprising at least one additional cell (C) near said second end of the mattress and a fifth connector connected to said additional cell(s), the control unit being configured to maintain inflation of said additional cell while said first, second, third and fourth groups of cells are cyclically inflated and deflated, whereby a patient on the mattress may be provided with constant support of their head when lying on said at least one additional cell.
The system of claim 1 or 2, wherein the control unit is configured to cyclically:
deflate mattress cells attached to said first and third connectors (A', A); inflate mattress cells attached to said first and third connectors; deflate mattress cells attached to said second and fourth connectors (B', B); and inflate mattress cells attached to said second and fourth connectors.
The system of any of claims 1 to 3, further comprising a pressure sensor (13) disposed between said first or second compressor and said connectors.
The system of any of claims 1 to 4, further comprising a quick release mechanism configured to permit rapid deflation of all of the cells.
The system of claim 5, wherein the quick release mechanism is configured to fully deflate the cells within 30 seconds of being activated, preferably within 15 seconds of being activated.