An inflatable pressure controlled mattress and a method to monitor a patient activity with an inflatable pressure controlled mattress

Abstract

The present invention relates to an inflatable pressure controlled mattress 1 for supporting and monitoring a patient's activity while lying on the mattress 1. The mattress 1 comprises an air cell layer 7 with air cells 14a-o, which collaborate with an air source providing pressurised air to the air cells 14a-o. The air source 16 is in communication with a processor regulating amount of pressurised air to the air cells 14a-o. The mattress 1 is arranged with a sensor layer 12 arranged with a first sensor pad 17 comprising a first air conduit 18 arranged in a serpentine pattern and connected to a first sensor 19. The first sensor 19 is communicating with the processor, whereby during a pre-defined time-frequency the first sensor 19 repeatedly register pressure of air in the air conduit 18 and generates an output signal for each repeated register and communicates the output signal to the processor whereby a patient activity may be monitored.

Description

[0001] AN INFLATABLE PRESSURE CONTROLLED MATTRESS AND A METHOD TO MONITOR A PATIENT ACTIVITY WITH AN INFLATABLE PRESSURE CONTROLLED MATTRESS

[0002] Field of the invention

[0003] The present invention relates to an inflatable pressure controlled mattress for supporting and monitoring a patient's activity while being arranged on the mattress. The present invention further relates to a method to monitor a patient activity with an inflatable pressure controlled mattress.

[0004] Background of the invention

[0005] Decubitus ulcers are a common negative effect that may occur when patients are inactive during longer period, for example being hospitalised and lying in bed. Decubitus ulcers are wounds, which may occur on skin areas on the patients when the patient is lying or sitting too long and are not moving or changing position enough. Not moving enough may further result in other complications for the patient, for example weakened muscular strength etc. It is therefore important for patients to move and regularly change their position when sleeping or sitting.

[0006] Presence and development of decubitus ulcers due to inactivity is a common occurrence and there have been many attempts with aim to reduce the risk for patients to develop decubitus ulcers. It is common that hospital staff follow a decided and regular schedule to assure the patient is visited by the medical caregivers to help the patient at regular intervals to change their position. However, each patient may have individual needs, and at hospitals it can occur that unforeseen situation happens which may cause delay or need for rescheduling the planned visits to the patient. A schedule to be followed is by its nature very dependent on the human who is supposed to do what the schedules says. Also, experience of the hospital staff may have an effect on the effectiveness and the accuracy for assuring the patient is being regularly activated for reducing the risk for the patient to develop decubitus ulcers.

[0007] Summary of the invention An object of the present invention is to provide an inflatable pressure controlled mattress to automatically detect if a patient has been inactive for an extended period of time. The inactivity may be that the patient hasn't significantly, over a period, changed their position with respect to the bed. A further object of the invention is to provide a method to monitor a patient movement's activity while the patient is lying on the mattress.

[0008] The objects are achieved with an inflatable pressure controlled mattress according to claim 1, and according to a method for monitor a patient activity with an inflatable pressure controlled mattress according to claim 15.

[0009] One embodiment of the invention relates to an inflatable pressure controlled mattress for supporting and monitoring a patient activity while being arranged on the mattress. The mattress comprises a head part, a feet part, a first and second long side, a top cover, an air cell layer, a sensor layer, and a base cover. The air cell layer is arranged with air cells which collaborate with an air source arranged to provide pressurised air to the air cells. The air source is in communication with a processor, which regulates amount of pressurised air from the air source to the air cells. The sensor layer is arranged with a first sensor pad comprising a first air conduit arranged in a serpentine pattern and connected to a first sensor. The first sensor is in communication with the processor, whereby during a predefined time-frequency the first sensor is adopted to repeatedly register pressure of air in the air conduit and generates an output signal for each repeated register and communicates the output signal to the processor. Pressure measurements are repeatedly taking place over a defined time-frequency and the respective pressure measurements are communicated and stored in the processor for processing. An effect of registering pressure measurements is that it is possible to evaluate the patient movements with respect to the mattress over a period. If the registered pressure measurements deviate only a little from a first performed pressure measurement it means the patient is moving too little. On the other hand, if the patient is active and frequently move, the activity will result in several different pressure changes as well as changes, variations, of size between the pressure changes. Combination of the pressure changes and the size of the pressure changes against the mattress may be indicated how the pressure and activity deviate over a period whereby it may be displayed on a display indicating the differences between the first pressure measurement and the proceeding and repeated pressure measurements.

[0010] According to one embodiment, the sensor layer is positioned in the mattress between a base pad and the base cover. The base pad is an internal mattress arranged with a pre-set hardness. The base pad functions as a support layer in case the air cells arranged in the cell layer accidently would lose its internal air pressure. As the air cells in such a situation would lose its effect to support a patient, the base pad would maintain some softness of the mattress for the patient lying on the mattress until the air pressure in the air cells is restored.

[0011] According to one embodiment, the first air conduit is arranged with a first inlet arranged at one edge part of the sensor pad, and the first air conduit is arranged with a first outlet arranged at one edge part of the sensor pad. According to a further embodiment, the first sensor is in cooperative connection with the first outlet. The first sensor is arranged to measure the pressure of the air present in the first air conduit.

[0012] According to one embodiment, the air source is in communication with the first sensor pad via a first air feed. The air source may be a compressor arranged to generate pressurised air. The air source communicates with the processor, which is arranged to provide instructions to the air source how of much air the air source shall generate to the air cells.

[0013] According to one embodiment, the first air feed, between the air source and the first sensor pad, comprises a first valve. The first valve is a non-return valve, may also be referred to as a one-way valve, whereby air may flow in only one direction from the air source and to the first air pad.

[0014] According to one embodiment, the first air feed, between the air source and the first valve communicates with an air feed sensor which is communicating with the processor. The air feed sensor is arranged to register the pressure in the first air feed.

[0015] According to one embodiment, the sensor layer is arranged with a second sensor pad comprising a second air conduit. According to a further embodiment, the second air conduit is in cooperative connection with a second sensor. An effect of the second sensor pad is that it is arranged in the mattress and in the mattress arranged to receive pressure indications over an area arranged for the patient legs. This may have a further effect that it may be possible to measure and identify differences of a patient movement activity comparing the movement activity of the patient upper body with the patient lower body, legs. In a further embodiment, the readings from the first and the second sensor may be combined whereby its results may be an average reading representing the movement activity of the whole patient body.

[0016] According to one embodiment, the second air conduit is arranged in a serpentine pattern in the second sensor pad. An effect of the serpentine pattern is that the air conduits may be arranged such that the air conduits extend over a majority of the respective measurement area for the respective sensor pad. A further effect of this may be that only two sensors, being the first sensor and the second sensor, are needed to register a patient movement activity when the patient is lying on the mattress.

[0017] According to one embodiment, the second air conduit is arranged with a second inlet arranged at one edge part of the second sensor pad, and the second air conduit is arranged with a second outlet arranged at one edge part of the second sensor pad. In one embodiment the second inlet and the second outlet may be arranged along one same edge part of the second sensor pad. An effect of having a first and second sensor pad comprising a respective inlet and outlet is that they may be arranged in the mattress as modules, which may facilitate assembly as well as possible replacement of the respective sensor pad.

[0018] According to one embodiment, the second air conduit has an extension within the second sensor pad, which is shorter than the first air conduit arranged within the first sensor pad. The first sensor pad is arranged for measuring pressure from the patient upper body lying against the mattress. The upper body of a patient is normally heavier than the legs. The air conduit is arranged to take up the pressure resulting from the weight from the patient and measure change of the pressure from the activity or movements of a patient. As the upper part of the patient body larger and heavier than the legs, the first sensor pad is arranged with a longer air conduit compared to the second sensor pad. According to one embodiment, a second air feed with a first end is arranged to the second inlet of the second sensor pad and with a second end is connected to a connecting point arranged on the first air feed, and to which connecting point an air feed sensor is arranged. In a further embodiment, the second air feed, between the connection point and the second inlet a second valve is arranged. The first and the second sensor pad receives its air from one and same air source. An effect that the air feed sensor is arranged on one side of the valves, being the first and the second valve, and the first and the second sensor is arranged on the side of the valves, is that it will be possible to measure the pressure difference between the air feed sensor and the respective first and second sensor. All the sensors are in communication with the processer and is arranged to obtain data from the sensors of the pressure each sensor registers. The data from the sensors may be processed in the processor whereby it may be detected and evaluated rate and amount of movement activity the patient on the mattress is generating.

[0019] According to one embodiment, the embodiment utilizes a method to monitor a patient activity with an inflatable pressure controlled mattress according to features as described above. The method comprising the following steps: arranging a patient in horizontal position on the mattress comprising a sensor layer with a first sensor pad having a first air conduit, indicating the patient weight into a processor, starting a period of a pre-defined time frequency, at start of the pre-defined time frequency, a first sensor registering a first pressure of air arranged in the first air conduit which pressure is affected by the patient weight and position on the mattress, the first sensor communicating the registered first pressure to a processor, after the start during the pre-defined time-frequency, the first sensor repeatedly registering pressures of the air arranged in the first air conduit and which pressures are affected and varied by the patient weight, position, and movements on the mattress, the first sensor communicating the repeated registered pressures to the processor, in the processor, determining rate of change of the repeated registered pressures having been registered during the pre-defined number of times at a pre-defined frequency with respect to the first registered pressure, in the processor, if the rate of change exceeds a pre-defined difference between the previous rate of change in the processor, add the rate of change of each registered pressure to an accumulator, in the processor, when the predetermined number of time is met add the accumulator to a rolling buffer with a pre-determined multiplier.

[0020] According to one embodiment, the method further comprises: at the start of the pre-defined time frequency, a second sensor registering a second pressure of air arranged in a second air conduit, the second sensor communicating the registered second pressure to the processor, after the start during the pre-defined time-frequency, the second sensor repeatedly registering pressures of the air arranged in the second air conduit and which pressures are affected and varied by the patient weight, position, and movements on the mattress, the second sensor communicating the repeated registered pressures to the processor, in the processor, determining rate of change of the repeated registered pressures having been registered during the pre-defined number of times at a pre-defined frequency with respect to the first registered pressure, in the processor, if the rate of change exceeds a pre-defined difference between the previous rate of change, in the processor, add the rate of change of each registered pressure to an accumulator, in the processor, when the predetermined number of times are met add the accumulator to a rolling buffer with pre-determined multiplier.

[0021] An effect of the method as described above is that the method is arranged to involve only one sensor for monitoring activity movements of a patient upper body as well as one sensor for monitoring the patient lower body, which are the legs. Because only one or two sensors may be used, electricity and other components needed for the functionality of the respective sensor may be kept to a minimum, which facilitates maintenance and use of the mattress.

[0022] According to a further embodiment, the method may further comprise that the values relating to the rate of change in the processor are compared to at least one threshold value. If the rate of change of at least one of the threshold value would fall short, this could result in generation of an alert signal. If, on the other hand, the rate of change would exceed the threshold value, then the method could be arranged to repeat the period. The at least one threshold value may be a first and second threshold value whereby the respective threshold value may be utilized in comparison with a rate of change value with respect to input signals from the respective first and second sensor to the processor. In a further embodiment, the first and second threshold value may be one same value.

[0023] Brief description of the drawings

[0024] The invention is described in more detail below with reference to the appended drawings in which:

[0025] Fig 1 is a schematic view of a mattress where main internal elements and components are disclosed.

[0026] Fig 2 is a schematic view of a system with elements and components for monitoring a patient's movement activity.

[0027] Fig 3 is schematic view of a patient lying on the mattress.

[0028] Fig 4 is flowchart of a method for the invention for monitoring a patient activity while the patient is arranged on the mattress. Detailed description of preferred embodiment of the invention

[0029] Fig 1 illustrates a schematic view of an inflatable pressure controlled mattress 1. To facilitate understanding, main elements and components being part of the mattress 1 in Fig 1 are for visualisation separated from each other. The mattress 1 comprises a head part 2, an opposite arranged feet part 3, a first and second long side 4, 5. The mattress 1 is arranged with a top cover 6. The top cover 6 represents the top part of the mattress 1. The top cover 6 may be covered by a sheet or other element, which will be arranged between the top cover 6 and a patient lying against the mattress 1. Against an underside of the top cover 6 is an air cell layer 7 arranged. The air cell layer comprises air cells 14a-p. The air cells 14a-p are tube formed comprising a long side and a respective short end. Respective air cell 14a-p extend between the first and the second long side 4, 5. The air cells 14a-p are arranged with their long sides next to each other, side by side, extending between the head part 2 and the feet part 3. Each air cell 14a-p is a closed volume, which each are in communication with a respective valve (not shown in figure). The respective valve may for example be a non-return valve. The respective valve being in communication with respective air cell 14a-p is communicating with an air source providing air to the valves and the respective air cell 14a-p. The respective short end of the air cells 14a-p are arranged with elements to connect with the valves and the air source. In Fig 1, for understanding, only air cells 14a, b, c, d, n, o and p are marked with a reference number. Beneath the air cell layer 7 is a cell holding element 8 arranged. The cell holding element 8 is arranged as a layer comprising connecting elements 15a-p. In Fig 1, for understanding, only connecting elements 15a, b, o and p are marked with a reference number. The connecting elements 15a-p are arranged to be connected with the respective air cell 14a-p for preventing the air cells 14a-p to move and loose its position in the mattress 1 during use. For example, when a patient is lying against the mattress 1 and if the patient is moving it may cause the air cells 14a-p to move in the mattress 1. Therefore, the air cells 14a-p are secured with connecting elements 15a-p. In one embodiment, the cell holding element 8 may be arranged below the air cells 14a-p. Beneath the cell holding element 8 is a first and second turning bladder 9, 10 arranged. The turning bladders 9, 10 are arranged to inflate and help a patient on the mattress 1 to change their position on the mattress 1. The first turning bladder 9 is arranged along the first long side 4 of the mattress 1. The second turning bladder 10 is arranged along the second long side 5 of the mattress 1. The first and the second turning bladder 9, 10 are arranged on a part of the mattress 1 which is arranged to mainly receive a patient upper body when the patient is lying on the mattress 1. During use, the first or the second turning bladder 9, 10 is inflated with air whereby its volume increases whereby the patient is pushed, or partly lifted, by the turning bladder 9, 10 for facilitating the patient to change their position on the mattress 1. The turning bladders 9, 10 are in communication with the air source. Beneath the mentioned first and second turning bladder 9, 10 a base pad 11 is arranged. The base pad 11 extend from the head part 2 to the feet part 3, and between the first and the second long side of the mattress 1. The base pad 11 may be pneumatic. The base pad is arranged with a pre-defined softness. In case something would happen with the mattress 1 while a patient is lying on it, for example if there would be a loss of the air pressure leading to the air cells 14a-o would lose its air pressure. Avoiding that the patient would lie flat on a hard surface, the base pad will thus function as a soft mattress whereby the patient may be lying fairly soft until the pressure in the air cells 14a-p is restored. Beneath the base pad 11 is a sensor layer 12 arranged. The sensor layer 12 may be arranged over a major area of the mattress 1 lying area. The sensor layer 12 is arranged with a first sensor pad 17. The first sensor pad 17 has an arrangement to obtain and sense pressure and / or pressure differences caused by movements form a patient upper body when the patient is lying on the top cover 6 of the mattress 1. The sensor layer 12 is arranged with a second sensor pad 25. The second sensor pad 25 has an arrangement to obtain and sense pressure and / or pressure differences caused by movements from a patient leg when the patient is lying on the top cover 6 of the mattress 1. The first sensor pad 17 is in the mattress arranged over a larger area then the second sensor pad 25. This because a patient upper body normally is larger and more heavy than the legs of the patient. Therefore, the first sensor pad 17 has a larger cover area of the mattress 1 than the second sensor pad 25. The first and the second sensor pad 17, 25 may be encapsulated between an upper protective layer 34 and a lower protective layer 35, together forming one unit. The upper protective layer 34 comprises a first safety opening 36a. The upper protective layer 34 may further comprise a second safety opening 36b. The sensor pads 17, 25 operate under pressure. In case of a possible accident causing a breakage or internal leakage of pressurised air, the pressurised air in the sensor pad 17, 25 may exit out through the safety openings 36a, 36b reducing risk the sensor pads 17, 25 would inflate to uncontrollable balloons causing a patient to fall of the mattress 1. According to one embodiment, the sensor layer 12 may be arranged between the cell holding element 8 and the base pad 11 (not shown in figure). Beneath the sensor layer 12 is a base cover 13 arranged. The base cover 13 has a rigid frame structure and supports and carries the described elements, which builds up the mattress 1. The base cover 13 may be arranged in a mechanical bed structure comprising wheels whereby the mattress 1 may be transported.

[0030] Fig 2 illustrates a schematic view of a system comprising the first and the second sensor pad 17, 25 and how they are connected and arranged with other components. The first and the second sensor pad 17, 25 are in Fig 2 only schematically illustrated whereby there may be visual differences in size between components with same reference numbers illustrated in Fig 1 and Fig 3. The first sensor pad 17 is arranged with a first air conduit 18. The first air conduit 18 is arranged in a serpentine pattern over a cover area of the first sensor pad 17. The first air conduit 18 comprises a first air inlet 20 and a first air outlet 21. To the first air conduit 18 is a first air feed 22 arranged. The first air feed 22 communicates with an air source 16. Along the first air feed 22 is a first valve 23 arranged. The first valve 23 may be a non-return valve. To the first air outlet 21 is a first sensor 19 arranged. The first sensor 19 may be a so-called input sensor. The first sensor 19 is arranged to register air pressure inside the first air conduit 18. The register of the air pressure by the first sensor 19 may be happening continuously. The first sensor 19 is in communication with a processor to which processor the registered values are sent as a signal from the first sensor 19. In the processor, during a pre-set time interval, the registered values from the first sensor 19 are registered. Depending on how the registered values from the first sensor 19 varies over the pre-set time interval, period, it may be determined if the patient is moving sufficiently or is moving too little whereby assisting personnel may be alerted to check on the patient. Along the first air feed 22, arranged between the air source 16 and the first valve 23, an air feed sensor 24 is arranged. The air feed sensor 24 may connect to the first air feed 22 via a connecting point 31 arranged along the first air feed 22. The air feed sensor 24 is arranged to register pressure of the air in the first air feed 22. The air feed sensor 24 is communicating with the processor whereby the pressure value registered by the air feed sensor 24 is sent as a signal to the processor. In the processor, the processor may comprise an algorithm, which may be arranged to take in the registered values from the first sensor 19 and from the air feed sensor 24. In one embodiment the registered values from the first sensor 19 and from the air feed sensor 24 may be processed and compared to each other to identify pressure differences and variations between the two sensors. During a pre-set time or period, if the differences don't vary it may indicate the patient is not moving whereby the processor may trigger an alert signal for attention. The first sensor pad 17, the first valve 23 and the air source 16 are arranged to cooperate and form together a system. In this system, the mentioned components are arranged to cooperate with each other.

[0031] Fig 2 illustrates the second sensor pad 25. The second sensor pad 25 is arranged as a further component to the mentioned system. The second sensor pad 25 comprises a second air conduit 26. The second air conduit 26 is arranged in a serpentine pattern in the second sensor pad 25. The serpentine pattern of the second air conduit 26 is arranged to extend over a cover area of the second sensor pad 26. Cover area of the first and the second sensor area is defined as an area of the sensor pad, which is facing upwards towards the top cover 6 of the mattress 1. The cover area is arranged to be the area, which is used for obtaining, and measure any pressure value from a patient weight lying on the mattress 1. The second air conduit 26 is arranged with a second inlet 28 and a second outlet 29. To the second inlet 28 is a second air feed 30 arranged. The second air feed 30 is arranged with the first air feed 22 via the connecting point 31. In one embodiment, the second air feed 30 may be arranged to the first air feed 22 via a second connecting point being separated from the mentioned connecting point 31 (not shown in figure). Along the second air feed 30, between the connecting point 31 and the second inlet 28 a second valve 32 is arranged. The second valve 32 may be a non-return valve. On the other end of the second air conduit 26, opposite the second inlet 28, a second outlet 29 is arranged. To the second outlet 29 a second sensor T1 is arranged. The second sensor T1 may be an input sensor, which may be a same type of sensor as the first sensor 19. The second sensor 27 is arranged to register air pressure inside the second air conduit 26. The second sensor T1 is in communication with the processor. Measurement values registered by the second sensor T1 is sent as input signals to the processor. The second sensor T1 may be arranged to register pressure inside the second air conduit 26 continuously whereby the processor continuously may be provided with data about the air pressure inside the second air conduit 26. During a pre-defined time frequency, pre-set time interval or period, measured register values may be communicated to the processor. In the processor, the values may be introduced into an algorithm whereby it is possible to determine pressure variations in the second air conduit 26 over the predefined time. Depending on the pressure variations, it may be determined how much or how little the patient has been moving while lying on the mattress 1. For example, if the patient is moving too little, it will show as being too little variations between the measured values whereby an alert or alarm notification signal will be generated by the processor for attention to personnel, for example hospital personnel, to arrive to the patient for providing the necessary help the patient might need.

[0032] Fig 2 illustrates the system comprising three sensors. The three sensors may be the first sensor 19, the second sensor 1 , and the air feed sensor 24. All the three sensors 19, T1 , 24 may communicate with the processor providing information about the air pressure from their respective measure points in the system to the processor. The information from the sensors 19, 1 , 24, which may be signals, to the processor are processed therein whereby it may be possible to determine how the pressure varies in the respective air conduit 18, 26. The processor may be arranged to combine the information from the first and the second sensor 19, 1 whereby movements by the patient full body may be determined and evaluated. In one embodiment, the processor may be arranged to process information from the first sensor 19 and the second sensor 1 independently from each other. Such an independently processing would make it possible to determine level of activity or movement of the upper body and the legs independently of each other.

[0033] Air source 16, processor, and possibly valves may be elements, which may be arranged outside the mattress 1 and may be in communication with the different elements of the mattress via wires and / or conduits. A reason why it may be preferably to have the air source 16 and the processor arranged outside the mattress 1 may be that they are electrical components. In a mattress for patients, it may be desirable to reduce possible risk of electrical shock to a patient lying on the mattress because of malfunction electrical components in the mattress 1. Therefore, the air source 16 and the processer may be placed outside the mattress 1.

[0034] Fig 3 illustrates a schematic view of the mattress 1 with an illustrated patient 33 placed in a horizontal position on the mattress 1. The patient 33 is arranged on the mattress 1 with their head towards the head part 2 and with their feet towards the feet part 3 of the mattress 1. Fig 3 further illustrates the first and the second sensor pad 17, 25 being part of the mattress 1. The elements in Fig 3, including the patient 33, are illustrates as see through elements with purpose to facilitate visualisation, reading and understanding of the mattress 1. The first and the second sensor pad 17, 25 are schematically illustrated whereby its respective size may differ compared to how they may be displayed in Fig 1 and Fig 2. During use, the patient 33 is positioned in a horizontal position against upper part of the mattress 1. In the mattress 1, over an area, which substantially is represented by upper body of the patient lying flat on the mattress 1, the first air pad 17 is arranged. Over an area, which substantially, or partly, is represented by the legs of the patient while the patient is lying flat on the mattress 1, the second air pad 25 is arranged. The first sensor pad 17 has a larger area, cover area, than the second sensor pad. This because the first sensor pad 17 is arranged to register change in activity from the patients 33 upper body, which normally is larger than the legs part being the patients 33 lower body. Width of the first and second sensor pad 17, 25 may substantially by the width of a patient shoulder.

[0035] Fig 4 illustrates flowchart for a method being applied during use of the embodiment. The method is arranged for monitoring the patient activity or level of movements on the mattress 1 where pressure signals are registered by the first and the second sensor 19, T1 and which signals are processed to provide indication of a patient movement. The method includes several steps between a start and end of the method, and which steps are:

[0036] I) The patient is arranged on the mattress 1 and applies a pressure against the mattress 1. II) The pressure is registered as pressure signals from the first and / or the second sensors 19, 1 and are sampled at a pre-determined rate. The pressure signals are registered by the sensors 19, T1 during a pre-determined period of time. The period may be a pre-defined time-frequency.

[0037] III) The registered pressure signals, pressures, are communicated as input signals to the processor. In the processor the pressure signals are inputs into an algorithm arranged in the processor.

[0038] IV) Each registered pressure signal is a sample, which is differentiated to compute a rate of change.

[0039] V) Each result of the differentiation function is inserted, processed, into an accumulator.

[0040] VI) After process of the result in the accumulator, a decision step is generated for determine if the pressure signal sampling period time has been reached.

[0041] VII) If the pressure signal sampling period time has not been reached or met, the method, process, is arranged to loop back for the pressure signal inputs to be sent as sample input to the algorithm in the processor, see step II.

[0042] VIII) If the sampling period time has been reached, the patient weight, which is known to the system, is provided as input to the algorithm in the processor. During start, or before start, information about the patient weight may be computed into the system by a user.

[0043] IX) The accumulator value is added to a rolling buffer array with a decaying multiplier.

[0044] X) A sum of the accumulated value is generated whereby the sum are processed into a plurality of digital closed loop filters of varying responsiveness and which output of these filters are compared being fast or slow with respect to each other.

[0045] XI) If the faster responsive filters' output is proportionally greater than the output of the slower responsive filters by a pre-determined amount, then the output delivers an increasing movement trend of the patient. On the contrary, if the slower responsive filters' output is proportionally greater than the output of the faster responsive filter by a predetermined amount, then the output delivers a decreasing movement trend of the patient. If neither of the above conditions are true, then the output delivers a no change in movement trend. No change in movement trends indicates the patient hasn't, substantially, changed their movement. The outputs may be presented as an indication of trend to a user interface, either increasing movement, decreasing movement or no significant change in trend.

[0046] XII) A normalization value may be calculated by utilizing a time period option value which may be selected by the user and in the processor combine the selected time period with the patient weight. The time period may be automatically selected or may be inputted by a user into the system.

[0047] XIII) The input from the selected time period and the patient weight is then processed through a range map converting the output of normalization into a numeric range depicted by a generated value between a zero value and maximum value which then may be output information to determine either increasing movement, decreasing movement or no significant change in movement. The normalisation value calculates the movement level of the patient, while the varying responsiveness calculates the movement trends. As provided from above steps, the output information as a normalised numeric range (for example 0-10) may be used in conjunction to determine total patient movement both current and recent historic.

[0048] XIV) After the calculations, either being movement level or movement trends, the method may be finalised by resetting of the the accumulator and resetting of the sampling period.

[0049] Movement detection by register of the input signals from the sensors in the mattress to the processor may trigger alert signals as explained. A further effect, or purpose, is that after the signals have been processed in the processor, the result of the processed signals may be displayed on a display or screen for visualisation to show numerically and / or graphically the movements of the patient over time. The visualisations enable the user to determine the patient activity on the mattress and identify trends of the patient activity. For example, how the level of movement is increasing or decreasing over time while the patient is lying on the mattress. The obtained knowledge of the trends can then be utilized in decisions how to possibly treat the patient, for example by medical professionals or other personnel within patient care.

[0050] Hereinbefore it has been described that the mattress may be arranged for patients for monitoring the patient activity while being arranged on the mattress. It will be appreciated that the principles and the method described above may be applied to other mattresses or other types of arrangements for supporting a patient.

[0051] Reference signs

[0052] 1. inflatable pressure controlled mattress

[0053] 2. head part

[0054] 3. feet part

[0055] 4. first long side

[0056] 5. second long side

[0057] 6. top cover

[0058] 7. air cell layer

[0059] 8. cell holding element

[0060] 9. first turning bladder

[0061] 10. second turning bladder

[0062] 11. pneumatic base pad

[0063] 12. sensor layer

[0064] 13. base cover

[0065] 14. air cells (a-o)

[0066] 15. connecting elements (a-o)

[0067] 16. air source

[0068] 17. first sensor pad

[0069] 18. first air conduit

[0070] 19. first sensor

[0071] 20. first inlet

[0072] 21. first outlet

[0073] 22. first air feed

[0074] 23. first valve

[0075] 24. air feed sensor

[0076] 25. second sensor pad

[0077] 26. second air conduit

[0078] 27. second sensor

[0079] 28. second inlet 29. second outlet

[0080] 30. second air feed

[0081] 31. connection point

[0082] 32. second valve 33. patient

[0083] 34. upper protective layer

[0084] 35. lower protective layer

[0085] 36. safety opening

Claims

Claims1. An inflatable pressure controlled mattress (1) for supporting and monitoring a patient activity while being arranged on the mattress (1), the mattress (1) comprises a head part (2), a feet part (3), a first and second long side (4, 5), a top cover (6), an air cell layer (7), a sensor layer (12), and a base cover (13), the air cell layer (7) is arranged with air cells (14a-o) which collaborate with an air source (16) arranged to provide pressurised air to the air cells (14a-o), the air source (16) is in communication with a processor which regulates amount of pressurised air from the air source (16) to the air cells (14a-o), the sensor layer (12) is arranged with a first sensor pad (17) that via a first air feed (22) is in communication with the air source (16), and with a first valve (23) arranged between the first sensor pad (17) and the air source (16), the first sensor pad (17) comprising a first air conduit (18) arranged in a serpentine pattern and connected to a first sensor (19), which first sensor (19) is in communication with the processor, whereby during a pre-defined time-frequency the first sensor (19) is adopted to repeatedly register pressure of air in the air conduit (18) and generates an output signal for each repeated register and communicates the output signal to the processor, characterized in that, the first valve (23) is a non-return valve, and the sensor layer (12) is arranged with a second sensor pad (25) comprising a second air conduit (26).

2. A mattress (1) according to claim 1, wherein the sensor layer (12) is positioned in the mattress (1) between a base pad (11) and the base cover (13).

3. A mattress (1) according to claim 1, wherein the first air conduit (18) is arranged with a first inlet (20) arranged at one edge part of the sensor pad (17), and the first airconduit (18) is arranged with a first outlet (21) arranged at one edge part of the sensor pad (17).

4. A mattress (1) according to claim 3, wherein the first sensor (19) is in cooperative connection with the first outlet (21).

5. A mattress (1) according to claim 1, wherein the first air feed (22), between the air source (16) and the first valve (23) communicates with an air feed sensor (24) which is communicating with the processor.

6. A mattress (1) according to claim 1, wherein the second air conduit (26) is in cooperative connection with a second sensor (27).

7. A mattress (1) according to claim 1, wherein the second air conduit (26) is arranged in a serpentine pattern in the second sensor pad (25).

8. A mattress (1) according to claim 1, wherein the second air conduit (26) is arranged with a second inlet (28) arranged at one edge part of the second sensor pad (25), and the second air conduit (26) is arranged with a second outlet (29) arranged at one edge part of the second sensor pad (25).

9. A mattress (1) according to claim 1, wherein the second air conduit (26) has an extension within the second sensor pad (25) which is shorter than the first air conduit (18) arranged within the first sensor pad (17).

10. A mattress (1) according to claim 8, wherein a second air feed (30) with a first end is arranged to the second inlet (28) of the second sensor pad (25) and with a second end is connected to a connecting point (31) arranged on the first air feed (22), and to which connecting point (31) an air feed sensor (24) is arranged.

11. A mattress (1) according to claim 8, wherein the second air feed (30), between the connection point (31) and the second inlet (28) is arranged with a second valve (32).

12. A method to monitor a patient activity with an inflatable pressure controlled mattress (1) according to claim 1 - 11, the method comprising the following steps: arranging a patient in horizontal position on the mattress (1) comprising a sensor layer (12) with a first sensor pad (17) having a first air conduit (18), indicating the patient's weight into a processor, starting a period of a pre-defined time frequency, at start of the pre-defined time frequency, a first sensor (19) registering a first pressure of air arranged in the first air conduit (18) which pressure is affected by the patient weight and position on the mattress (1), the first sensor (19) communicating the registered first pressure to a processor, after the start during the pre-defined time-frequency, the first sensor (19) repeatedly registering pressures of the air arranged in the first air conduit (18) and which pressures are affected and varied by the patient weight, position, and movements on the mattress (1), the first sensor (19) communicating the repeated registered pressures to the processor, in the processor, determining rate of change of the repeated registered pressures having been registered during the pre-defined number of times at a pre-defined frequency with respect to the first registered pressure, in the processor, if the rate of change exceeds a pre-defined difference between the previous rate of change, in the processor, add the rate of change of each registered pressure to an accumulator, in the processor, when the predetermined number of time is met add the accumulator to a rolling buffer with a pre-determined multiplier.

13. A method to measure a patient activity according to claim 12, the method comprises: at the start of the pre-defined time frequency, a second sensor (27) registering a second pressure of air arranged in a second air conduit (26) the second sensor (19) communicating the registered second pressure to the processor, after the start during the pre-defined time-frequency, the second sensor (27) repeatedly registering pressures of the air arranged in the second air conduit (26) and which pressures are affected and varied by the patient weight, position, and movements on the mattress (1), the second sensor (27) communicating the repeated registered pressures to the processor, in the processor, determining rate of change of the repeated registered pressures having been registered during the pre-defined number of times at a pre-defined difference frequency with respect to the first registered pressure, in the processor, if the rate of change exceeds a pre-defined difference between the previous rate of change, in the processor, add the rate of change of each registered pressure to an accumulator, in the processor, when the predetermined number of time is met add the accumulator to a rolling buffer with a pre-determined multiplier.