GB2594135A

GB2594135A - Seat pad system

Info

Publication number: GB2594135A
Application number: GB2101899.9A
Authority: GB
Inventors: Lewis Jon
Original assignee: Direct Healthcare Group Ltd
Current assignee: Direct Healthcare Group Ltd
Priority date: 2017-11-24
Filing date: 2017-11-24
Publication date: 2021-10-20
Anticipated expiration: 2037-11-24
Also published as: GB2594135A8; GB2594135B; GB2594135B8; GB202101899D0

Abstract

A seat pad comprises a plurality of air holding zones 22 & 24, a pump unit 30 arranged to supply air to each of the zones such that they can be independently adjusted, a pressure sensor arranged to measure pressure in each zone and a control unit 34 to inflate the zones in dependence on the detected pressure. The device may have a calibration mode based on a deflation time which indicates the weight distribution of a patient. The pressure in the chambers 22 & 24 may be cyclically varied. The control unit 34 may respond to a pressure hotspot by adjusting the relative pressure of zones. The pressure sensor may be pads which extend over or under the zones. The pump may have a manifold with a plurality of valves. The air holding zones may also have foam. The device may detect a risk of ulcers or provide an alarm to indicate a lack of movement.

Description

Seat Pad System

Field of the Invention

The present invention concerns a mattress arrangement and mattress. More particularly, but not exclusively, this invention concerns a mattress to assist in the prevention of pressure sores, and a method of reducing pressure sores.

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 mattress 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 -2 -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 special mattresses. Conventional pressure relief mattresses include specialised foam mattresses comprising a foam base and a specially contoured foam insert on which the patient body is supported. These mattresses may be known as static mattresses. Although such mattresses may be effective at preventing the development of pressure sores, some patients may require more assistance to keep moving. Alternative mattresses may be provided, such as an inflatable mattress. This type of mattress comprises a series of inflated sections. Such mattresses may be permanently inflated or the inflatable sections may be partially or wholly inflated/deflated using motorised pumps. Where a pump is used, each inflatable section is in fluid communication with the pump, the pump selectively inflating and deflating each inflatable section thereby gently moving the patient supported on the mattress. These mattresses may be known as dynamic mattresses. Various different inflation/deflation algorithms may be used depending on the patient need. However, where a mattress is continuously operated in a dynamic mode it may make it more difficult for the patient to sleep.

The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved mattress and mattress system. -3 -

Summary of the Invention

The present invention provides, according to a first 5 aspect, a mattress system, the mattress system comprising: a mattress, the mattress comprising a plurality of air-holding zones, a pump unit, the pump unit arranged to supply air to each of the plurality of air-holding zones such that the pressure in each of the air-holding zones can be adjusted independently, a pressure sensor, the pressure sensor arranged to detect and monitor the pressure experienced by each air-15 holding zone, and a control unit, the control unit arranged to receive pressure data from the pressure sensor and determine the supply of air to each of the air-holding zones based on the pressure data and control the pump unit accordingly.

A mattress system according to the present invention allows the pressure within each of the plurality of air-holding zones to be adjusted based on the actual pressure exerted on the zones by a patient lying on the mattress. For example, if the pressure sensor detects that the pressure on one zone of the mattress is significantly higher than surrounding zones, this may indicate the presence of a pressure hotspot. Such pressure hotspots may result in pressure ulcers forming. In response to detection of the hotspot, the control unit may control the pump to Increase the pressure in the air-holding zones surrounding the hotspot zone. The control unit may be configured such that, in response to detection of a pressure hotspot in a first air-holding zone, the control unit controls the pump so as to change the relative -4 -pressure between the first air-holding zone and a second air-holding zone adjacent to the first air zone.

Alternatively or additionally, the mattress system may be arranged such that the air supply to one or more individual air-holding zones is constantly varied in dependence on the pressure detected relating to that air-holding zone. In such an arrangement, it may be necessary to include a static pause, where the air supply to the air-holding chambers is switched off or diverted, and the pressure related to each air-holding zone is re-measured. In such a way, the movement of a patient can be compensated for over time.

The mattress system may comprise a calibration mode. The calibration mode may comprise configuring the control unit to increase the pressure within each of the plurality of air-holding zones to a first pressure, for example 30mmHg, then allow the deflation of the plurality of air-holding zones to a second pressure, for example 6mmHg, and monitoring and recording the deflation time.

The time taken to deflate from the first pressure to the second pressure, i.e. the deflation time, may indicate the approximate weight of a patient, and by monitoring each air-holding zone separately, may indicate the weight distribution of the patient across the mattress. For example, a heavier patient may have a shorter deflation time than a lighter patient. The zones where a heavier load from the patient is transmitted, for example underneath the hips of a patient, may have a shorted deflation time than a zone where a lighter load from the patient is transmitted, for example under the knees of a patient. The pressure supplied to each of the pressure holding zones, for example the pressure change cycles when the mattress is in an active mode (in which the pressure within an air-holding zone is increased and -5 -decreased alternately), may be tailored to each air-holding zone based on the pressure detected during the calibration mode. The mattress system may be configured to regularly enter the calibration mode to ensure that any changes in patient position are compensated for, which otherwise may create hotspots which could cause ulcers. For example, the mattress system may be configured to enter the calibration mode every ten minutes.

The mattress system may be arranged such that in response to detection of a pressure hotspot in an air-holding zone, the control unit is configured to control the pump unit to increase the pressure in at least one air-holding zone adjacent to the air-holding zone associated with the pressure hotspot.

The mattress system may be arranged such that in response to detection of a pressure hotspot in an air-holding zone, the control unit is configured to control the pump unit to reduce the pressure in that air-holding zone.

The mattress system may comprise an active mode, wherein the control unit is configured to cyclically vary the pressure in each air-holding zone based on data received from the pressure sensor. When operating in an active mode, the mattress system may be arranged such that in response to a detection of a pressure hotspot in an air-holding zone, the control unit is configured to cyclically vary the pressure within that air-holding zone in a different way to neighbouring air-holding zones, for example by cycling pressure at a different frequency, and/or between greater or smaller end pressures. The optimum settings for the active mode may be determined by testing patients, and monitoring various different pressure distributions, adjusting the various settings and analysing the outcomes accordingly. The skilled -6 -person will understand the process used, and no further details will provided herein.

Therefore, the weight of the patient may be more evenly spread, and the pressure on a particular part of the patient reduced, thereby also reducing the likelihood of a pressure ulcer forming. Alternatively or additionally, when operating in an active mode, adjustments may be tailored to specific high risk areas as determined by the pressure detected associated with those areas. Such a system allows real time adaptation of the mattress to compensate for the physical positioning of the patient.

The skilled person will appreciate that a pressure hotspot may extend over one or more of the plurality of air-holding zones. In such a scenario, the apparatus may be operated in the same way as described above, save that the pressure may be reduced in each of the air-holding zones over which the hotspot is detected, and/or by increasing the pressure in the surrounding air-holding zones.

The pressure sensor may comprise a pressure sensing pad (or mat) which extends either over or under the plurality of air-holding zones. In such an arrangement, the pressure sensor detects the pressure being exerted by a patient on the air-holding zones, as that pressure is transmitted through the air-holding zones. The pressure sensor may comprise a plurality of pressure sensing pads which extend either over or under the plurality of air-holding zones. The pressure sensor may comprise a plurality of pressure sensors which detect the air pressure within each of the plurality of air-holding zones. Detection of the pressure within each of the plurality of air-holding zones may be referred to as detection of the back pressure within the plurality of air-holding zones.

Each of the plurality of air-holding zones may be individually connected to the pump unit. Each of the plurality of air-holding zones may be connected to the pump unit by a pressure input tube, or other suitable air delivery system, the pressure input tube arranged to enable the passage of air from the pump unit into the air-holding zone. The pressure input tube may be used by the pump unit to increase the pressure inside the air-holding zone. Each of the plurality of air-holding zones may comprise a pressure outlet valve. The pressure outlet valve may be configured such that pressure is released from the air-holding zone when the pressure within that air-holding chamber exceeds a threshold amount. Each of the plurality of air-holding zones may be connected to the pump unit by a pressure outlet tube, or other suitable air delivery system, the pressure outlet tube arranged to enable the passage of air from the air-holding zone into the pump unit. The pressure outlet tube may be used by the pump unit to decrease the pressure inside the air-holding zone. The pressure input tube and the pressure output tube may be the same tube. In an alternative arrangement, the pressure input tube and the pressure outlet tube may be different tubes, each tube comprising a one-way air valve to ensure that air passes only in the desired direction. As will be appreciated by the skilled person, the pump unit may comprise both a "blow" mode, which may be used to increase pressure within am air-holding zone, and a "suck" mode, which may be used to reduce pressure within an air-holding zone. There may be 4-20 air-holding zones. The pressure in each of the plurality of air-holding zones may be controllable independently of the pressure in the other air-holding zones. The pressure in each of the plurality of air-holding zones may be controllable so as to remain constant over time, rather than being cyclically varied as in other air-holding zones. Such an arrangement would allow a healthcare professional or other user to "turn off" certain zones of the mattress, such that pressure remains constant, when a pressure ulcer is already present on a patient. Such an arrangement would allow the reduction of risk of other pressure sore forming, whilst also preventing the aggravation of the existing pressure sore by a repeated increase of pressure in the associated air-holding zone.

The pump unit may comprise a manifold, the manifold comprising a plurality of valves, for example solenoid valves, via which air supply to the plurality of air-holding zones is controlled. At least one of the air-holding zones may comprise a single air-holding chamber. At least one of the one air-holding zones may comprise a plurality of interconnected air-holding chambers. At least one of the air-holding zones may comprise a foam portion. At least one of the air-holding zones may be substantially free of any material other than air.

An air-holding chamber may comprise a foam section surrounded by an airtight plastic chamber. The foam section may have a contoured cross-section. An air-holding chamber may comprise an airtight plastic chamber with no interior material, other than air. The plurality of air-holding zones may comprise a mix of foam and no-foam air-holding chambers.

The control unit may be configured to increase and/or decrease the pressure within the plurality of air-holding zones only when the pressure sensor detects pressure hotspots which indicate a risk of a pressure ulcer forming. Such an arrangement may be advantageous -9 -in allowing a patient to sleep more easily on the mattress when they are not in an at risk position.

The control unit may be configured to increase and/or decrease the pressure within the plurality of air-holding zones such that the difference in pressure being exerted on each of the plurality of air-holding zones is kept within an allowable range. Such an arrangement will ensure that the pressure exerted on a patient will remain at a consistent level and the development of hotspots is prevented or reduced.

The control unit may be configured such that in response to the pressure sensor readings indicating that a patient has not moved for a certain period of time, an alarm is activated. The alarm may be visible or audible alarm within the proximity of the mattress system, or it may be an electronic notification sent to a computer, or smart device such as a smart phone or tablet.

The control unit may be configured such that in response to a sudden pressure drop across the whole of the mattress, a fall alarm is activated. This configuration may be an optional function that is activated by a user or healthcare professional only when the patient is bed-bound, as otherwise a patient getting out of bed may result in false alarms being triggered.

The control unit may be configured to communicate with the pressure sensor by wired or wireless communication. The control unit may be configured to communicate with the pump unit by wired or wireless communication. Provision of a wireless control unit may allow the analysis of the pressure sensor readings to be done on a computer remote from the mattress. Provision of a wireless control unit may allow a single computer unit to act as a control unit for a plurality of -10 -mattresses, for example all of the mattresses in a hospital ward.

According to a second aspect of the invention there is also provided a method of controlling a mattress system, the mattress system being a mattress system according to the first aspect, the method comprising the steps of: the pressure sensor monitoring the pressure exerted on the mattress, the control unit analysing the pressure sensor readings, based on the analysis of the pressure sensor readings, the control unit controlling the pump such that the pressure within one or more of the air-holding zones is adjusted.

The method may comprise the step of operating one or more of the air-holding zones in an active mode, where pressure is alternately increased and decreased in the air-holding zone, and the control unit controlling the pump such that the frequency of the alternate increase and decrease in pressure, and/or the end points of the increase and decrease in pressure, are determined based on the pressure detected within that air-holding zone.

The analysis of the pressure sensor readings may 25 include any or all of the following: * a comparison of absolute pressure values across the mattress, * a comparison of relative difference in pressure values across the mattress, * a comparison of absolute and/or relative pressure values across the mattress over a set time period.

The presence of a pressure hotspot may be indicated by any or all of: * a threshold pressure value being exceeded, * a threshold relative difference in pressure values being exceeded, * a pressure value not changing over a threshold period of time The mattress system may be calibrated such that the pressure sensor readings detected by the pressure sensor are associated with the air-holding zones that physically correspond to the location at which the pressure sensor reading is taken. Therefore, for each hotspot detected, there will be an associated air-holding zone. The control unit may be configured to control the pump such that when a pressure hotspot is detected, the pressure inside the air-holding zone which corresponds in location to the hotspot is reduced. The control unit may be configured to control the pump such that when a pressure hotspot is detected, the pressure is increased inside the air-holding zones adjacent to the air-holding zone corresponding to the pressure hotspot. As such, the pressure experienced by the patient may be reduced at the pressure hotspot. Alternatively or additionally, the method may comprise the control unit constantly (for example cyclically) varying the pressure within the air-holding zones. The variation in pressure may be determined based on the pressure detected during the pressure detection step, therefore providing a mattress system which automatically adjusts the pressure variation cycle based on the real-time patient positioning.

The method may comprise the step of continuous monitoring of the pressure exerted on the mattress, and continuous adjustment of the pressure within the various air-holding zones by the pump unit. The method may comprise the step of maintaining the pressure within the -12 -plurality of air-holding zones when the pressure sensor does not detect any pressure hotspots.

The method may comprise a calibration step, comprising configuring the control unit to increase the pressure within each of the plurality of air-holding zones to a first pressure, for example 30mmHg, then allowing the deflation of the plurality of air-holding zones to a second pressure, for example 6mmHg, and monitoring and recording the deflation time. The time taken to deflate from the first pressure to the second pressure, i.e. the deflation time, may indicate the approximate weight of a patient, and by monitoring each air-holding zone separately, may indicate the weight distribution of the patient across the mattress. The pressure supplied to each of the pressure holding zones, for example the pressure change cycles when the mattress is in an active mode, may be tailored to each air-holding zone based on the pressure detected during the calibration mode. The mattress system may be configured to regularly enter the calibration mode to ensure that any changes in patient position, which may for example move where potential hotspots will cause ulcers, is compensated for. For example, the mattress system may be configured to enter the configuration mode every ten minutes.

According to a third aspect, the invention may provide a method for determining the weight distribution of a patient on a mattress, the mattress comprising a plurality of air-holding zones with a pressure sensor associated with each of the air holding zones, and a pump unit arranged to supply air to each of the air-holding zones, the method comprising the steps of: activating the pump unit to increase the pressure within each of the air-holding zones to a first pressure, -13 -allowing the deflation of each of the air-holding zones to a second pressure, and monitoring the deflation time between the first pressure and second pressure for each of the air-holding zones. The method may further comprise the step of comparing the deflation times to a calibration table of deflation times, thereby arriving at an approximate weight being exerted on each of the air-holding zones. According to a fourth aspect, the invention may provide a mattress system comprising a plurality of air holding zones and pressure sensors associated with each of the air-holding zones, and pump unit configured to supply air to each of the air-holding zones, wherein the mattress system is configured for use according to the method as described with reference to the third aspect of the invention.

According to a fifth aspect, the invention provides a method of calibrating a mattress system, the mattress system comprising a plurality of air-holding zones connected to a pump unit, the method comprising the steps of: applying a first known weight distribution across the plurality of air-holding zones, the pump unit inflating the air-holding zones to a first pressure, allowing the air-holding zones to deflate to a second pressure and monitoring the deflation time between the first pressure and second pressure, recording the weight distribution and associated deflation times, repeating the method steps with a second weight distribution, the second weight distribution being different to the first weight distribution. By such a method, and repeating the method steps any number of times, a database of deflation times and weight distributions may be compiled.

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 -14 -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 10 accompanying schematic drawings of which: Figure 1 shows an example pressure map of a patient lying on a mattress; Figure 2 shows a mattress system according to a first embodiment of the invention; and Figure 3 shows a mattress system according to a second embodiment of the invention.

Detailed Description

Figure 1 shows an example pressure map 10 of a patient when lying on a mattress. The pressure map may be obtained by a pressure sensing pad, and would be understood by the person skilled in the art. The pressure map shows the pressure that is being exerted on a mattress by various parts of the patient's body. The map can indicate pressure hotspots, which may lead to pressure ulcers being formed.

Figure 2 shows a mattress system 20 according to a first embodiment of the invention. The mattress system 20 comprises a mattress 21 with a plurality of air-holding zones, in this case each air-holding zone comprising a single air-holding chamber 22, 24, 26, 28. Four air-holding chambers are shown, but the skilled -15 -person will appreciate that any suitable number of air-holding chambers may be used. Each of the air-holding chambers 22, 24, 26, 28, is connected by a tube 22', 24', 26', 28', to a pump unit 30. The pump unit 30 is arranged such that it may supply air or remove air from each of the air-holding chambers via the respective tubes. In alternative embodiments, each of the air-holding chambers may comprise distinct air inlet and air outlet tubes and/or valves. A pressure sensor pad 32 is located underneath the plurality of air-holding chambers 22, 24, 26, 28. The pressure sensor pad 32 is configured such that the pad is divided into zones which correspond to each of the plurality of air-holding chambers 22, 24, 26, 28. When a patient is lying on the mattress 21, the patient will be exerting a force on the various air-holding chambers. By detecting the pressure being exerted on the pressure pad, in particular with reference to the various zones corresponding to the plurality of air-holding chambers, the pressure experienced across various parts of a patient may be determined. The pressure readings detected by the pressure sensor pad 32 are sent from the pressure sensor pad 32 to a control unit 34. The control unit 34 is also connected to the pump unit 30, such that the control unit may operate the pump unit 30 to control the amount of air within each of the air-holding chambers. The pump mechanism within the pump unit is of conventional design and will need no further explanation to the person skilled in the art.

The pump unit may comprise a manifold, the manifold comprising a plurality of valves which are used to control the airflow from the pump unit 30 into each of the plurality of air-holding chambers 22, 24, 26, 28. The pump unit 30 may be arranged to operate continuously, with the airflow into the air-holding chambers controlled -16 -by the control unit adjusting the various valves in the manifold appropriately. In alternative embodiments, the pump unit may be associated with a remote manifold, the pump unit and manifold being located at different areas of the mattress system.

The operation of the mattress system is as follows. A patient will lie on the mattress 21. As the patient does this, the pressure sensor pad 32 detects the pressure exerted across the mattress. The measurements taken by the pressure sensor pad 32 are sent to the control unit 34 which analyses the results to determine whether any pressure hotspots are indicated. The analysis is done by a computer process located within the control unit, as would be easily understood by the person skilled in the art. As such, the CPU will not be described any further. If a pressure hotspot is detected, the control unit may control the pump unit 30 to decrease the pressure in the air-holding chamber which corresponds to the location of the pressure hotspot.

Doing so should spread the load of the patient more evenly onto the surrounding air-holding chambers and thereby reduce or remove the pressure hotspot. In addition to, or instead of, this reduction in pressure in the air-holding chamber which corresponds in location to the pressure hotspot, the control unit may control the pump unit to increase the pressure in the air-holding chambers surrounding, or adjacent, the pressure hotspot. This =crease in pressure within those air-holding chambers should more evenly spread the load of the patient, and therefore reduce or remove the pressure hotspot. The pressure sensor pad 32 and the control unit 34 may be arranged to continuously monitor the pressure being exerted by a patient, in order that changes in position of the patient may be compensated for. As such, -17 -the mattress provides real-time pressure relief, and is specifically governed by the actual state of the patient, rather than relying on a pre-determined pressure change algorithm which may not be best suited to the patient.

The analysis of the pressure sensor pad readings may include some or all of the following steps: * a comparison of the pressure readings across different zones of the pressure sensor pad. In the event of detecting a threshold difference in pressure readings between adjacent zones, the pump unit may be activated. The control unit may be configurable to choose between different threshold differences in pressure, as most appropriate to the patient using the mattress. For example, such threshold values may be determined by the weight and/or height of the patient.

* a comparison of the pressure sensor readings over a set time period. In the event of detecting no change in pressure readings over the set time period, the pump unit may be activated. The control unit may be configurable to choose between different set time periods, as different time periods may be appropriate for different patients.

* a comparison of the pressure sensor readings with respect to an absolute pressure threshold value.

In the event of detecting a pressure reading over the absolute threshold value, the pump unit may be activated. The control unit may be configurable to choose between different absolute pressure threshold values, as different values may be appropriate for different patients. For example, the threshold value may be determined on the basis of the patient's weight and/or height.

-18 -In the embodiment described with reference to figure 2, the pressure sensor pad 32 is located underneath the plurality of air-holding chambers. However, the skilled person will appreciate that the pressure sensor pad could easily be placed on top of the plurality of air-holding chambers and still operate in the way described above.

In a yet further embodiment as shown in figure 3, the pressure sensor pad 32 could be replaced by pressure sensors 22", 24", 26", 28", which are associated with, and directly detect the pressure within, the corresponding air-holding chambers 22, 24, 26, 28. An advantage of such a system is that the mattress system may include a calibration mode. In the calibration mode, the control unit supplies air to each of the air-holding chambers such that each chamber is pumped up to a first pressure, for example 30mmHg. The control unit 34 is then configured to allow the air-holding chambers to deflate to a second pressure, for example 6mmHg. The deflation time between the first pressure and second pressure will depend on the weight of the patient being exerted on each individual pressure chamber. Therefore, by monitoring the deflation times for each of the individual air-holding chambers, it is possible to approximate the weight being exerted on each of the air-holding chambers. Based on this approximation, the control unit may control the airflow into and out of each of the air-holding chambers, for example when operating the mattress in an active mode, cycling the pressure between a high pressure and low pressure, where the high pressure and low pressure values are determined based on the approximate weight on each air-holding zone. Alternatively or additionally, the frequency of the pressure changes may be determined based on the approximate weight being exerted on each air-holding -19 -zones. The mattress may enter the calibration mode periodically during operation in the active mode.

In the active mode, the mattress can be put into a state of configuration (either automatically or manually) in which the cyclic inflation and deflation of one or more air holding zones is turned off. This may be in response to a pressure hotspot in that area and/or due to that area corresponding to a known pressure ulcer.

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. By way of example only, certain possible variations will now be described.

The control unit in the figures described above is configured for wired communication with the pressure sensor and the pump unit. In an alternative embodiment, the pump unit may be configured for wireless communication with the pressure sensor and the pump unit. Such an arrangement may allow the analysis to be done remotely from the mattress.

The skilled person will appreciate that whilst the term "mattress" is used, and this will usually be interpreted to mean a mattress on a bed, the invention is equally applicable to a cushion, seat pad, or seat backrest, and such minor variations are encompassed by the following claims.

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 -20 -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.

Further aspects of the invention are set out in the following clauses: 1. A mattress system, the mattress system comprising: a mattress, the mattress comprising a plurality of air-holding zones, a pump unit, the pump unit arranged to supply air to each of the plurality of air-holding zones such that the pressure in each of the air-holding zone can be adjusted independently, a pressure sensor, the pressure sensor arranged to 20 detect and monitor the pressure experienced by each air-holding zone, and a control unit, the control unit arranged to receive pressure data from the pressure sensor and determine the supply of air to each of the air-holding zones in dependence on the detected pressure in each zone and control the pump unit accordingly.

2. A mattress system according to clause 1, comprising a calibration mode, the calibration mode comprising configuring the control unit to increase the pressure within each of the plurality of air-holding zones to a first pressure, then allowing the deflation of the plurality of air-holding zones to a second pressure, and monitoring and recording the deflation time.

-21 - 3. A mattress system according to clause 2, wherein the control unit is configured to compare the deflation time to a database of deflation times to indicate the weight distribution of a patient across the mattress.

4. A mattress system according to clause 3, wherein the pressure supplied to each of the air-holding zones, is tailored to each air-holding zone based on the pressure detected during the calibration mode.

5. A mattress system according to any of clauses 2 to 10 4, configured to regularly enter the calibration mode, thereby ensuring that any changes in patient position are compensated for.

6. A mattress system according to any preceding clause, arranged such that the air supply to one or more individual air-holding zones is constantly varied in dependence on the pressure detected relating to that air-holding zone.

7. A mattress system according to any preceding clause, the mattress system comprising an active mode, wherein the control unit is configured to cyclically vary the pressure in each air-holding zone based on data received from the pressure sensor.

8. A mattress system according to clause 1, wherein the control unit is configured such that, in response to detection of a pressure hotspot in a first air-holding zone, the control unit controls the pump so as to change the relative pressure between the first air-holding zone and a second air-holding zone adjacent to the first air-holding zone.

9. A mattress system according to any preceding clause, wherein in response to detection of a pressure hotspot in an air-holding zone, the control unit is configured to control the pump unit to increase the pressure in at -22 -least one air-holding zone adjacent to the air-holding zone associated with the pressure hotspot.

10. A mattress system according to any preceding clause, wherein in response to detection of a pressure hotspot in an air-holding zone, the control unit is configured to control the pump unit to reduce the pressure in that air-holding zone.

11. A mattress system according to any preceding clause, wherein the pressure sensor comprises a pressure sensing 10 pad which extends either over or under the plurality of air-holding zones.

12. A mattress system according to any preceding clause, wherein the pressure sensor comprises a plurality of pressure sensing pads which extend either over or under 15 the plurality of air-holding zones.

13. A mattress system according to any of clauses 1 to 10, wherein the pressure sensor comprises a plurality of pressure sensors which detect the air pressure within each of the plurality of air-holding zones.

14. A mattress system according to any preceding clause, wherein each of the plurality of air-holding zones is individually connected to the pump unit.

15. A mattress system according to any preceding clause, wherein the pump unit comprises both a "blow" mode, for increasing pressure within an air-holding zone, and a "suck" mode, for reducing pressure within an air-holding zone.

16. A mattress system according to any preceding clause, wherein the pump unit comprises a manifold, the manifold 30 comprising a plurality of valves via which air supply to the plurality of air-holding chambers is controlled.

17. A mattress system according to any preceding clause, wherein at least one air-holding zone comprises a single air-holding chamber.

-23 - 18. A mattress system according to any preceding clause, wherein at least one air-holding zone comprises a plurality of interconnected air-holding chambers.

19. A mattress system according to any preceding clause, 5 wherein at least one air-holding zone comprises a foam portion.

20. A mattress system according to any preceding clause, wherein at least one air-holding zone is substantially free of any material other than air.

21. A mattress system according to any preceding clause, wherein the control unit is configured to increase or decrease the pressure within the plurality of air-holding zones only when the pressure sensor detects a pressure hotspot which indicates the risk of a pressure ulcer forming.

22. A mattress system according to any preceding clause, wherein the control unit is configured to increase or decrease the pressure within the plurality of air-holding zones such that the difference in pressure detected across each of the plurality of air-holding zones is kept within an allowable range.

23. A mattress system according to any preceding clause, wherein the control unit is configured such that in response to the pressure sensor readings indicating that a patient has not moved for a certain period of time, an alarm is activated.

24. A method of controlling a mattress system, the mattress system according to clause 1, the method comprising the steps of: the pressure sensor monitoring the pressure exerted on the mattress, the control unit analysing the pressure sensor readings, -24 -based on the analysis of the pressure sensor readings, the control unit controlling the pump such that the pressure within one or more of the air-holding zones is adjusted.

25. A method according to clause 24, comprising the step of operating one or more of the air-holding zones in an active mode, where pressure is alternately increased and decreased in the air-holding zone, and the control unit controlling the pump such that the frequency of the alternate increase and decrease in pressure, and/or the end points of the increase and decrease in pressure, are determined based on the pressure detected within that air-holding zone.

26. A method according to clause 24 or 25, the method comprising a calibration step, comprising the control unit controlling the pump to increase the pressure within each of the plurality of air-holding zones to a first pressure, then allowing the deflation of the plurality of air-holding zones to a second pressure, and monitoring and recording the deflation time.

27. A method according to clause 26, wherein the deflation time is used to indicate the approximate weight of a patient on an air-holding zone.

28. A method according to clause 26 or 27, wherein the 25 pressure supplied to each of the pressure holding zones, is tailored to each air-holding zone based on the weight distribution detected during the calibration mode.

29. A method according to any of clauses 26 to 28, wherein the mattress system is configured to regularly 30 enter the calibration mode.

30. A method according to any of clauses 24 to 29, wherein the analysis of the pressure sensor readings includes any or all of the following: -25 - * a comparison of absolute pressure values across the mattress, * a comparison of relative difference in pressure values across the mattress, * a comparison of absolute and/or relative pressure values across the mattress over a set time period.

31. A mattress system according to any of clauses 24 to 30, wherein the mattress system is calibrated such that the pressure sensor readings detected by the pressure sensor are associated with the air-holding zone that physically corresponds to the location at which the pressure sensor reading is taken, such that for each hotspot detected, there will be an associated air-holding zone.

32. A method according to clause 31, further comprising the step of: when a pressure hotspot is detected, reducing the pressure inside the air-holding zone which corresponds in location to the hotspot 33. A method according to clause 31 or 32, further comprising the step of: when a pressure hotspot is detected, increasing the pressure inside the air-holding chambers adjacent the air-holding chamber corresponding to the pressure hotspot.

34. A method according to any of clauses 24 to 33, further comprising the step of continuous monitoring of the pressure exerted on the mattress, and continuous adjustment of the pressure within the various air-holding zones by the pump unit.

35. A method according to any of clauses 24 to 34, further comprising the step of maintaining the pressure within the plurality of air-holding zones when the pressure sensor does not detect any pressure hotspots.

-26 - 36. A method according to any of clauses 24 to 35, further comprising the step of triggering an alarm if the pressure sensor detects that a patient has not moved for a set period of time.

Claims

-27 -Claims 1. A seat pad system comprising: a seat pad comprising four air-holding zones, a pump unit, the pump unit arranged to supply air to each of the air-holding zones such that the pressure in each of the air-holding zones can be adjusted independently, a pressure sensor, the pressure sensor arranged to 10 detect and monitor the pressure experienced by each air-holding zone, and a control unit, the control unit arranged to receive pressure data from the pressure sensor, determine the supply of air to each of the air-holding zones in dependence on the detected pressure in each zone and control the pump unit accordingly, wherein the seat pad system is operable in a calibration mode, the calibration mode comprising configuring the control unit to increase the pressure within each of the air-holding zones to a first pressure, then allowing the deflation of the air-holding zones to a second pressure, and monitoring and recording the deflation time, wherein the control unit is configured to compare the deflation time to a database of deflation times to determine a weight distribution of a patient across the seat pad, the control unit further being arranged to analyse the pressure data to determine the presence of a pressure hotspot by comparing relative differences in pressure values across the seat pad, wherein the presence of a pressure hotspot is indicated by a threshold relative difference in the pressure values being exceeded, -28 -wherein the control unit is operable in an active mode in which the control unit controls the pump unit to cyclically vary the pressure within each air-holding zone by alternately increasing and decreasing the pressure between two end pressures at a given frequency, wherein in the active mode, the pressure supplied to each of the air-holding zones during the cyclic variation of pressure is based on the weight on each air-holding zone as determined during the calibration mode, and in response to detection of a pressure hotspot at a first of the air-holding zones, the control unit is configured to cyclically vary the pressure within the first air-holding zone in a different way to neighbouring air-holding zones in order to reduce the pressure at the hotspot.
2. A seat pad system as claimed in claim 1, wherein the pressure within a first of the air-holding zones is cyclically varied in a different way to neighbouring air-holding zones by cycling the pressure at a different frequency, and/or between greater or smaller end pressures.
3. A seat pad system as claimed in claim 1 or 2, configured to regularly enter the calibration mode, 25 thereby ensuring that any changes in patient position are compensated for.
4. A seat pad system as claimed in any preceding claim, wherein the pressure sensor comprises a pressure sensing 30 pad which extends either over or under the plurality of air-holding zones.
5. A seat pad system as claimed in any preceding claim, wherein the pressure sensor comprises a plurality of -29 -pressure sensing pads which extend either over or under the plurality of air-holding zones.
6. A seat pad system as claimed in any of claims 1 to 5 3, wherein the pressure sensor comprises a plurality of pressure sensors which detect the air pressure within each of the plurality of air-holding zones.
7. A seat pad system as claimed in any preceding claim, 10 wherein each of the plurality of air-holding zones is individually connected to the pump unit.
8. A seat pad system as claimed in any preceding claim, wherein the pump unit comprises both a "blow" mode, for increasing pressure within an air-holding zone, and a "suck" mode, for reducing pressure within an air-holding zone.
9. A seat pad system as claimed in any preceding claim, 20 wherein the pump unit comprises a manifold, the manifold comprising a plurality of valves via which air supply to the plurality of air-holding chambers is controlled.
10. A seat pad system as claimed in any preceding claim, 25 wherein at least one air-holding zone comprises a single air-holding chamber.
11. A seat pad system as claimed in any preceding claim, wherein at least one air-holding zone comprises a 30 plurality of interconnected air-holding chambers.
12. A seat pad system as claimed in any preceding claim, wherein at least one air-holding zone comprises a foam portion.
-30 - 13. A seat pad system as claimed in any preceding claim, wherein at least one air-holding zone is substantially free of any material other than air.
14. A seat pad system as claimed in any preceding claim, wherein the control unit is configured to increase or decrease the pressure within the plurality of air-holding zones such that the difference in pressure detected across each of the plurality of air-holding zones is kept within an allowable range.
15. A seat pad system as claimed in any preceding claim, wherein the control unit is configured such that in response to the pressure sensor readings indicating that a patient has not moved for a certain period of time, an alarm is activated.
16. A method of controlling a seat pad system, the seat 20 pad system as claimed in claim 1, the method comprising the steps of: the pressure sensor monitoring the pressure exerted on the seat pad, the control unit analysing the pressure sensor readings to determine the presence of a pressure hotspot by comparing relative differences in pressure values across the seat pad, wherein the presence of a pressure hotspot is indicated by a threshold relative difference in pressure 30 values being exceeded, operating the control unit in the active mode in which the control unit controls the pump unit to cyclically vary the pressure within each air-holding zone -31 -by alternately increasing and decreasing the pressure between two end pressures at a given frequency, in response to a detection of a pressure hotspot at a first of the air-holding zones, cyclically varying the pressure within the first air-holding zone in a different way to neighbouring air-holding zones in order to reduce the pressure at the pressure hotspot, and performing a calibration step, comprising the control unit controlling the pump to increase the pressure within each of the air-holding zones to a first pressure, then allowing the deflation of the plurality of air-holding zones to a second pressure, and monitoring and recording the deflation time, wherein the deflation time is used to determine a weight distribution of a patient across the seat pad, and wherein the pressure supplied to each of the air-holding zones is based on the weight on each air-holding zone as determined during the calibration mode.
17. A method as claimed in claim 16, wherein the step of operating the control unit in the active mode comprises controlling the pump such that, for each air-holding zone, the frequency of the alternate increase and decrease in pressure, and/or the end points of the increase and decrease in pressure, are determined based on the pressure detected within that air-holding zone.
18. A method as claimed claim 16 or 17, wherein the seat pad system is configured to regularly enter the 30 calibration mode.
19. A method as claimed in any of claim 16 to 18, wherein the analysis of the pressure sensor readings further includes: -32 - * a comparison of absolute pressure values across the seat pad, and/or * a comparison of absolute and/or relative pressure values across the seat pad over a set time period.
20. A method as claimed in any of claims 16 to 19, wherein the seat pad system is calibrated such that the pressure sensor readings detected by the pressure sensor are associated with the air-holding zone that physically corresponds to the location at which the pressure sensor reading is taken, such that for each hotspot detected, there will be an associated air-holding zone.
21. A method as claimed in any of claims 16 to 20, further comprising the step of continuous monitoring of the pressure exerted on the seat pad, and continuous adjustment of the pressure within the various air-holding zones by the pump unit.
22. A method as claimed in any of claims 16 to 21, further comprising the step of maintaining the pressure within the plurality of air-holding zones when the pressure sensor does not detect any pressure hotspots.
23. A method as claimed in any of claims 16 to 22, further comprising the step of triggering an alarm if the pressure sensor detects that a patient has not moved for a set period of time.