A mattress having an automatic pressure adjustment

Abstract

This invention relates in general to medical patient support apparatuses having a mattress with air cells and a control unit adapted to adjust air pressure in the air cells of the mattress. Principal function of this invention described herein is an automatic pressure adjustment in the individual air cells depending on loading of these air cells developed by a patient being supported on a mattress.

Description

[0001] A Mattress Having an Automatic Pressure Adjustment

[0002] Technical Field

[0003] This invention relates in general to medical patient support apparatuses having a mattress with air cells and a control unit adapted to adjust air pressure in the air cells of the mattress. Principal function of this invention described herein is an automatic pressure adjustment in the individual air cells depending on loading of these air cells developed by a patient being supported on a mattress.

[0004] Prior Art

[0005] Prior art or state of the art in healthcare area recognizes known patient support apparatuses for medical or nursery care used with different types of therapeutic patient supports (or mattresses) being located on a support deck of patient support apparatuses. Such known therapeutic patient supports are active mattress and reactive mattresses adapted to provide passive and active therapy. In addition, active mattresses can be alternating pressure mattresses or non-alternating pressure mattress. Alternating pressure mattresses offer active therapy and are designed to periodically relieve the pressure on patients’ skin by changing pressure in air cells. These types of mattresses are typically targeted at patients at higher risk of pressure ulcers and are often used for patients with already full thickness pressure ulcers.

[0006] The other aforesaid type of active pressure mattresses are non-alternating pressure mattresses which have typically constantly low pressure. Mattress pressure is as low as possible, however, not as low or zero to prevent contact of a patient body with a support deck of a patient support apparatus when lying on mattress being supported on the deck. Advantage of having low pressure in a mattress is elimination of risk of decubitus or pressure ulcers occurrence. Pressure adjustment in these active nonalternating mattresses is provided manually, which is time demanding and uncomfortable for patients as well as caregivers, on the other side. In ideal case, mattress air pressure should be adjusted so that sensitive parts of human body being prone to decubitus or pressure ulcers cannot be in contact with rigid parts of support deck of the patient apparatus. A patient weight and distribution of the patient's weight on the mattress need to be considered when adjusting air pressure. Due to health condition and different positions of a patient, however, optimal adjustment is difficult and, also, time demanding. Very often is such air pressure adjustment provided manually and on higher pressure value than needed to keep patient in safety conditions, yet this might be inconvenient from the medical point of view. Predetermined higher air pressure may cause occurrence of decubitus or pressure ulcers if the mattress does not alternate or is not reconfigured in more frequent periods of time.

[0007] Another problem may appear in case the support deck of the patient support apparatus is divided into several parts, typically back rest part, leg part, foot part, which are pivotably coupled and enable e.g. raising of the back rest part into the lifted position in which the patient may be positioned in seating position. In such position the air cells in the part where patient sits are loaded with higher weight. Should a compressor be not activated to add air, the active mattress may bottom out and, depending on the weight and time period the patient's body is in contact with a solid part of the support deck, the patient is at risk of developing pressure ulcers. To prevent developing of pressure ulcers, many other complex mattress systems have been developed that use various types of sensors. Such sensors can be located in each supporting pressure-exposed area, or they can be located throughout the mattress in each of the inflatable air cells. Such mattresses respond to various changes in the patient’s positions and to different loads in a given area, where the patient more or less develops load on the given area or cell. These mattresses also evaluate and respond to signals and subsequently adjust the pressure automatically. However, even such sophisticated mattress systems pertain with certain disadvantages.

[0008] Significant disadvantage of the aforesaid highly sophisticated mattress systems is high purchase and, also, production price, in addition, in case of a malfunction or failure of any sensor it is necessary to repair, often at high costs, or even replace the entire mattress. Such mattress systems also require expensive servicing. Another disadvantage is that sensors are electronically connected, which is one of the risk factors in patient care, as in case electrical connection between the sensors fail, the patient may be unexpectedly and suddenly hit by electric voltage.

[0009] Prior art recognizes number of therapeutic mattresses which eliminate the above- mentioned risk of decrease of pre-adjusted (or predetermined) low pressure and consequent mattress bottoming out. For example, some mattresses have pre-adjusted higher pressure in the lower air cells and lower pressure in the upper air cells is controlled by one-way valves by releasing air in dependence on the load developed by a patient. The control unit of these mattresses coordinates inflation of the upper and iower ceii Sayers separately so that the lower layer has a higher pressure than the upper layer. An example of such a solution is, for example, disclosed in the patent US 6148461 by Huntleigh Technology. Another technical solution is disclosed in a patent application US2014059781 A1 by Stryker Corporation. To determine optimal pressure in a patient support, such as mattress, the application teaches depth sensors adapted to detect and measure the degree of penetration of a patient into the mattress. Used sensors are placed in the mattress cells and generate a signal sensing the degree of penetration into the mattress. An air pressure sensor is also included that measures the pressure inside at least one cell. A suitable inflation level of the mattress is determined by monitoring the rate of change of the depth with respect to air pressure as the bladder is either inflated or deflated. Evaluation of status sensed by sensors is controlled by control unit which consequently defines volume of inflation or deflation of air in the mattress cells. This technical solution is very sophisticated, however also very expensive. In case the control unit has no backup power source, such mattress is not functional without power supply and the patient is likely to be endangered by developing of pressure ulcers or decubitus. Should control unit evaluate sensing data improperly or a failure of device occur, the air pressure in the cells may be changed more frequently than desired and this can be very uncomfortable for the patient. Patient may feel like swinging or laying on waves which consequently may develop suffering from nausea.

[0010] Another technical solution is disclosed in a patent US8844079B2 by Hill-Rom company, which uses data uploaded by a user to adjust optimum pressure, also based on factor or a value known as “bottoming-out“. Bottoming-out value is a pressure value upon full immersion of a patient to which a certain constant value is added to avoid full immersion or bottoming out being a target status. Technical solution uses sensors and control unit to evaluate data and adjust volume of inflation or deflation of air in the mattress cells. Disadvantage of this solution is again dependency on power supply and electronic components which may become faulty, and again very high price of the system. Another disadvantage is improper selection of air pressure optimizing by the user.

[0011] Another technical solution is disclosed in a patent US10492619B2 by Paramount Bed company, which appears to be the closest prior art to the solution disclosed herein. Nevertheless, also this patented solution differs significantly as the control unit of mattress deflates and inflates air in mattress ceils based on reference value by means of change of conditions or statuses per a definite period of time. The control unit controls air pressure by means of comparing the set reference value and measuring of plurality of changes in status per time period. This control method is not precise, lengthy and is not automatic as the reference valued needs to be defined and set.

[0012] Due to certain aforesaid shortcomings, it was necessary to develop a matress having pressure optimizing system that would respond not only to a patient's weight but also to the position of the patient on a support deck or on a mattress supported such patient. A method and a special mattress have been developed which are able to automatically determine patient's weight based on minimum input information and to predict possible rate of immersion or bottoming-out with the fact that a compressor of such mattress will automatically inflate of deflate air volume based on pressure changes generated or developed by a patient being supported on a mattress. Summary of the Invention

[0013] Aforesaid challenges and disadvantages of known pressure air systems are overcome by below described patient support, or a mattress, adapted to be used on patient support apparatuses in healthcare or nursing facilities providing long term care or short-term care for patients. A mattress comprises plurality of air cells which are grouped in groups identified as A, B, C and S. The mattress may comprise one or two layers of air cells, or one or plurality of groups of air cells, or may combine a foam layer and plurality of air cells. Air cell assemblies may be a combination of different groups, such as combination of A and B groups, or A and B and C groups, or A and B and C and S groups, where S group (standing for „static") represents a plurality of air cells that have constant, i.e. static or unchanging pressure.

[0014] Air cells pertaining to one group, either A group, or B group, or C group, or S group, are mutually connected by pneumatic connection in the form of hoses or any similar material. Each group of air cells is coupled by pneumatic connection to a compressor via distributing unit which is a part of the compressor. The compressor further comprises an air pump, a control unit and a pressure sensor. The air pump is coupled to the distribution unit and the control unit. The control unit is connected to the pressure sensor. Pneumatic connection of air cells in one group may be provided by hoses, or combination of hoses and connection components and couplers that connect the individual hoses to the individual air cells, or the air cells are connected in a chain by couplers and connecting valves so that air can be inflated to air cells of the mattress properly and equally. Inflation and deflation of air cells is controlled by the control unit of the compressor. The pressure sensor located in the compressor measures pressure in the individual groups of air cells, the measured values are processed by the control unit which consequently controls the process of pressure air adjustment in the mattress.

[0015] Technical solution disclosed herein describes automatic pressure air adjustment in a mattress based on evaluation of weight of a patient being supported on a mattress, either when laying or sitting. Based on this evaluated weight of patient air pressure is adjusted in the mattress correspondingly for such a particular patient. Evaluation of patient's weight is calculated by measuring of pressure increase in one or more air cell groups during measuring procedure after placing the patient on any patient support, or mattress.

[0016] Technical solution of mattress assembly disclosed herein does not comprise any other additional or accessory sensors located inside the mattress, underneath the mattress, or anywhere else on the patient support apparatus or patient support deck. Nor the assembly needs any other measuring pressure mats or pads located on the patient support apparatus, measuring pillows or any other measuring devices, special sensors, or sensors. Also, no weighing or scale system being installed on a patient support apparatus or any other accessory system that would process patient's weight and thus evaluated patient's weight is used.

[0017] Process of automatic air pressure adjustment comprises several steps. First, all groups of air cells are inflated to predefined air pressure. When starting the process of inflation and deflation of air cells, these air cells need to be loaded with a patient, i.e. the patient needs to be supported on a mattress. Consequently, one or more groups of air cells are deflated to lower pressure, however not zero pressure. Following, second or other groups of air cells are deflated to the air pressure close to zero pressure. In case mattress comprises one group or more groups of static air cells S, i.e. ceils with constant unchanging pressure, these air cells stay away from the process of inflation and deflation of air cells, i.e. these air cells remain inflated all the time. This basic principle uses two methods of measuring and adjustment of air pressure in a mattress. First method of measuring and adjustment of air pressure in a mattress includes below described process of measuring and adjusting values. All groups of air cells are inflated to a certain predefined air pressure. When starting the process of inflation and deflation of air cells, these air cells need to be loaded with a patient, i.e. the patient needs to be supported on a mattress. One group of air cells is identified as measuring group of air cells, for example group A. Air pressure in this group A is consequently deflated to lower pressure, however not completely zero pressure. Inflation, as well as deflation, of the individual air cells is controlled by the control unit of the compressor. Upon following deflation of second group of air cells, or other group of air cells (B, C etc.) to nearly zero pressure, the loading developed by a patient being supported on a mattress generates change of pressure in the measuring group of air cells and this pressure increase in the measuring group of air cells is measured by control unit. Pressure increase value is Δ Pa(delta Pa). The resulting mattress air pressure Pvis formulated as:

[0018] Pv= f(Δ P3) The control unit may repeat this process more times in cyclic, or in case the control unit detects change of load in one group or plurality of groups of air cells, or always when a patient being supported on a mattress is changed.

[0019] Second method of measuring and adjustment of air pressure in a mattress includes below described process of measuring and adjusting values. All groups of air cells are inflated to a certain predefined air pressure. When starting the process of inflation and deflation of air cells, these air cells need to be loaded with a patient, i.e. the patient needs to be supported on a mattress. Two groups or more groups of air cells are identified as measuring groups of air cells, for example groups B, and C. Air pressure in these groups B and C is consequently deflated to lower pressure having different value for each group, however not completely zero pressure. Inflation, as well as deflation, of the individual air cells is controlled by the control unit of the compressor. Upon following deflation of third group of air cells, or any other group of air cells (A etc.) to nearly zero pressure, the loading developed by a patient being supported on a mattress generates change of pressure in the measuring groups of air cells. As each of these measuring groups of air cells was deflated to different low pressure value, resulting pressure increase is different in measuring group B (increase Δ Pb) and different in measuring group C (increase Δ Pc) based on loading of group A of air cells by a patient. The resulting mattress air pressure Pv is formulated as: Pv= f (Δ Pb + Δ Pc)

[0020] The control unit may repeat this process more times in cyclic according to patient's needs, or in compliance with the pressure change sensed by and processed by control unit, also in cases when a patient is supported on mattress for a long time (e.g. intensive care units) and weight of such patient changes in time due to weight loss and muscle loss, or fat gain and weight gain. The control unit of the compressor is capable also to detect change of a patient being supported on a mattress and respond properly and fast by adjusting air pressure accordingly.

[0021] The control unit defines weight of a patient being supported on a mattress based on measured value Δ Pa, Δ Pb or Δ Pc.

[0022] In another embodiment, each compressor may comprise a backup power source which is charged by integrated charger, or by using charging cable or docking station, if needed.

[0023] List of Drawings

[0024] Various features and attendant advantages of disclosed technical solution will become more fully appreciated when considered in a view of the accompanying drawings, in which like reference characters designate the same or similar parts and / or features throughout, wherein:

[0025] Fig. 1 shows scheme of mattress design comprising plurality of air cells and a compressor.

[0026] Fig. 2 shows different mattress designs comprising plurality of air cells.

[0027] Fig. 3 shows scheme of mattress design comprising smaller number of air cells and a compressor.

[0028] Fig. 4 shows different mattress designs comprising smaller number of air cells.

[0029] Fig. 5 shows graphic diagram of first method of measuring.

[0030] Fig. 6 shows graphic diagram of second method of measuring. List of References

[0031] 1) mattress

[0032] 2) group of air cells A

[0033] 3) group of air cells B 4) group of air cells C

[0034] 5) group of air cells S

[0035] 6) foam base (of a matress)

[0036] 7) pneumatic connection

[0037] 8) compressor 9) pressure sensor

[0038] 10) air distribution unit

[0039] 11) pump

[0040] 12) control unit

[0041] 13) layout design of air ceils (of a matress) 14) layout design of air cells (of a mattress)

[0042] 15) layout design of air cells (of a matress)

[0043] 16) layout design of air cells (of a mattress)

[0044] 17) layout design of air cells (of a mattress)

[0045] 18) layout design of air cells (of a mattress) 19) layout design of air cells (of a mattress)

[0046] 20) layout design of air cells (of a matress)

[0047] Exemplary Embodiments of the Invention

[0048] The technical solution disclosed herein is predominantly adapted to patient supports, or mattresses, used in healthcare and nursery facilities for long-term bedridden patients, or patients changing weight due to their disease character. The system of disclosed automatic air pressure adjustment can be, however used, with patient supports, or matresses, in healthcare facilities where patients are changed frequently on such matresses or when loading on the individual air cells is changed frequently due to changing of positions of patients. Should a patient lie on his back on a patient support, the weight is equally distributed over all individual air cells. In case a patient changes position to lie on one side or to be in a sitting position, the mattress is loaded unequally due to patient weight. Therefore, air pressure needs to be adjusted to avoid any undesired full immersion or bottoming-out of the patient, to avoid having too rigid or soft mattress which may cause undesired developing of pressure ulcers or decubitus, for which value of patient weight is of essential importance.

[0049] Fig. 1 shows scheme of design of a patient support, a matress 1. The mattress 1 comprises plurality of groups of air cells 2 to 5. Air cells 2 to 5 are made of plastic material or any other airtight and impermeable fabrics or other material. Air cells are grouped into groups that are hereinafter identified as a group of air cells A 2, a group of air cells B 3, a group of air cells C 4 and a group of air cells S 5 having static air pressure, i.e. constant pressure air. The individual figures show these groups under numbers 2, 3, 4 and 5. All air cells within each one air cell group 2 to 5 are mutually interconnected pneumatically by means of pneumatic connection 7 that can consist of hoses made of plastic material, rubber or any other material convenient for air blowing and inflation of air cells 2 to 5. The entire one group of air cells (A, B, C, S) 2 to 5 is pneumatically connected by pneumatic connection 7 to a compressor 8 via a distribution unit 10. The compressor 8 further comprises a pump 11 and a control unit 12, which is connected to a pressure sensor 9, which is further pneumatically connected to the distribution unit 10. The pump 11 is pneumatically connected to the distribution unit 10. said pump 11 is electrically connected to the control unit 12. The pressure air adjustment system comprises one pressure sensor 9, in preferred embodiment there can be plurality of pressure sensors 9.

[0050] Fig. 2 shows cross section views of different mattress 1 designs comprising plurality of air cells. Layout design of air cells 13 of a mattress 1 comprises one layer of air cells where, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3, which is next to a group of air cells C 4, and such changing pattern is engaged along the entire longitudinal side of the mattress 1 which supports the major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is located. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. All groups of air cells (A, B, C, S - 2 to 5) are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0051] Another embodiment of layout design of air cells 14 is shown with a mattress 1 comprising a foam base 6 positioned on the bottom part of the mattress 1 along the entire longitudinal side of the mattress 1- One layer of air cells resides on the foam base 6. Wherein, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3^ which is next to a group of air cells C 4, and such changing pattern of group of air cells A, B, C (2 to 4) is engaged along the entire longitudinal side of the mattress 1 which supports a major part of a body of a patient. At the head end part of the mattress X underneath a patient’s head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. The foam base 6 as well as all groups of air cells (A, B, C, S - 2 to 5) are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0052] Another embodiment of layout design of air cells 15 is shown with a mattress 1 comprising one layer of group of air cells S 5, which are inflated to predefined constant air pressure. These groups of air cells S 5 are engaged on the bottom part of the mattress 1 forming a continuous level along the entire longitudinal side of the mattress 1_. One layer of air cells resides on the layer of group of air cells S 5. Wherein, in reciprocate manner, a group of air ceils A 2 is next to a group of air cells B 3, which is next to a group of air cells C 4, and such changing pattern of group of air cells A, B, C (2 to 4) is engaged along the entire longitudinal side of the mattress 1. which supports a major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. The layer of group of air cells S 5 as well as al! groups of air cells (A, B, C, S - 2 to 5) of the second layer are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0053] Another embodiment of layout design of air cells 16 is shown in Fig. 2 with a mattress 1 comprising two layers of group of air ceils (A, B, C, S ~ 2 to 5). The first bottom layer of the mattress 1 comprising groups of air cells where, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3, which is next to a group of air cells C 4. and such changing pattern of group of air cells A, B, C (2 to 4) is engaged along the entire longitudinal side of the mattress 1 which supports a major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. Another layer of air cells resides on the first layer of group of air cells engaging the same design of changing the individual air groups of air cells (A, B, C, S - 2 to 5). The first layer of group of air cells A, B, C, S ~ 2 to 5) as well as another layer of groups of air cells (A, B, C, S - 2 to 5) residing on the first layer are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0054] Fig. 3 shows scheme of mattress 1_ design comprising smaller number of air cells A, B, C (2 to 4). Groups of air cells A, B, C (2 to 4) are made of plastic material or any other watertight and impermeable fabrics or material. Air cells are grouped into groups that are hereinafter identified as a group of air cells A 2, a group of air cells B 3, a group of air cells C 4 and a group of air cells S 5 having static air pressure, i.e. constant pressure air. The individual figures show these groups under numbers 2, 3, 4 and 5. All air cells within each one air cell group 2 to 5 are mutually interconnected pneumatically by means of pneumatic connection 7 that can consist of hoses made of plastic material, rubber or any other material convenient for air blowing and inflation of air cells 2 to 5. The entire one group of air cells (A, B, C, S) 2 to 5 is pneumatically connected by pneumatic connection 7 to a compressor 8 via a distribution unit 10. The compressor 8 further comprises a pump 11 and a control unit 12, which is connected to a pressure sensor 9, which is further pneumatically connected to the distribution unit 10, The pump 11 is pneumatically connected to the distribution unit 10, said pump 11 is electrically connected to the control unit 12. The pressure air adjustment system comprises one pressure sensor 9, in preferred embodiment there can be plurality of pressure sensors 9. The pressure sensor 9 may be located directly on the 11 in preferred embodiment, optionally the pressure sensor 9 con be connected directly in the distribution unit 10.

[0055] Fig. 4 shows different mattress 1_ designs comprising smaller number of air cells comparing to Fig. 2. Layout design of air cells 17 of a mattress 1. comprises one layer of air cells where, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3, and such changing pattern is engaged along the entire longitudinal side of the mattress 1 which supports the major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is located. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. All groups of air cells (A, B, S - 2, 3, 5) are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0056] Another embodiment of layout design of air cells 18 is shown with a mattress 1 comprising a foam base 6 positioned on the bottom part of the mattress 1 along the entire longitudinal side of the mattress L One layer of air ceils resides on the foam base 6. Wherein, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3 and such changing pattern of group of air cells A, B, (2, 3) is engaged along the entire longitudinal side of the mattress 1. which supports a major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. The foam base 6 as well as all groups of air ceils (A, B, S - 2, 3, 5) are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impemieabie material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0057] Another embodiment of layout design of air ceils 19 is shown with a mattress 1 comprising one layer of group of air cells S 5, which are inflated to predefined constant air pressure. These groups of air ceils S 5 are engaged on the bottom part of the mattress 1 forming a continuous level along the entire longitudinal side of the mattress 1 One iayer of air cells resides on the layer of group of air cells S 5. Wherein, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3, and such changing pattern of group of air cells A, B (2., 3) is engaged along the entire longitudinal side of the mattress 1 which supports a major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. The layer of group of air cells S 5 as well as all groups of air cells (A, B, S - 2, 3, 5) of the second layer are placed inside a mattress cover that creates an external upper surface of the mattress 1. made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0058] Another embodiment of layout design of air cells 20 is shown in Fig. 4 with a mattress 1 comprising two layers of group of air cells (A, B, S ~ 2, 3, 5). The first bottom layer of the mattress 1 comprising groups of air cells where, in reciprocate manner, a group of air cells A 2 is next to a group of air cells B 3, and such changing pattern of group of air ceils A, B (2, 3) is engaged along the entire longitudinal side of the mattress 1 which supports a major part of a body of a patient. At the head end part of the mattress 1, underneath a patient's head, only a group of air cells S 5 is positioned. This group comprises air cells that do not alternate and are permanently set for one constant air pressure. Another layer of air cells resides on the first layer of group of air cells engaging the same design of changing the individual air groups of air cells (A, B, S - 2, 3, 5). The first layer of group of air cells A, B, S - 2. 3. 5) as well as another layer of groups of air cells (A, B, S - 2, 3, 5) residing on the first layer are placed inside a mattress cover that creates an external upper surface of the mattress 1 made from impermeable material easy for maintaining and cleaning to remove any appropriate impurities and undesired liquids and provide necessary disinfection.

[0059] Fig. 5 shows graphic diagram of a first method of measuring of air pressure. First method of measuring and adjustment of air pressure in a mattress 1 includes below described process of measuring and adjusting values. All groups of air cells 2 to 5 (A, B, C, S) are inflated to a certain predefined air pressure. When starting the process of inflation and deflation of air cells 2 to 5 (A, B, C, S), these air cells 2 to 5 (A, B, C, S) need to be loaded with a patient, i.e. the patient needs to be supported on a mattress 1. Inflation of the air cells 2 to 5 (A, B, C, S), as well as deflation of these air cells 2 to 5 (A, B, C, S) is controlled by a control unit 12 of a compressor 8. One group of air cells is identified as measuring group of air cells, for example group A 2. Air pressure in this group A 2 is consequently deflated to lower pressure, however not completely zero pressure. Upon following deflation of second group of air cells B 3, or other group of air cells C 4 etc. to nearly zero pressure, the loading developed by a patient being supported on a mattress 1 generates change of pressure in the measuring group of air cells A 2. This pressure increase in the measuring group of air cells A 2 is measured by control unit 12 as a pressure increase in the measuring group of air cells A 2. The pressure increase value is identified in the graph as A Pa (delta Pa). The control unit 12 of the compressor 8 calculates resulting air pressure based on pressure increase Δ Pa in the measuring group of air cells A 2. The compressor 8 consequently adjust the resulting pressure in the T The control unit 12 may repeat this process more times in cyclic according to patient's needs, or in compliance with the pressure change in any of the group of air cells A, B, C (2, 3, 4) sensed by and processed by control unit 12, also in cases when a patient is supported on mattress 1 for a long time (e.g. intensive care units) and weight of such patient changes in time due to weight loss and muscle loss, or fat gain and weight gain. The control unit 12 of the compressor 8 is capable also to detect change of a patient being supported on a mattress 1 and respond properly and fast by adjusting air pressure accordingly.

[0060] Pressure profile in the individual groups of air cells A, B, C (2, 3, 4) is shown in the graph by curves A, B, C.

[0061] Fig. 6 shows graphic diagram depicting graphically how air pressure in the individual air cells A, B, C (2, 3, 4) changes throughout the measuring process.

[0062] Method of measuring of pressure differences in a mattress 1 shown in the graph in Fig. 6 comprises all groups of air cells 2 to 5 (A. B, C, S) that are inflated to certain higher pressure by a control unit 12 of a compressor 8. in another embodiment, such higher pressure is predefined in the control unit 12 or is manually set by a caregiver. At least two groups of air cells 2, 3, 4 (A, B, C) are identified as measuring air cells - it can be a combination of air cells 2, 3 (A, B), or 2, 4 (A, C), or 3, 4 (B, C). Yet in another embodiment, measuring air cells can be all groups of air cells 2, 3, 4 (A, B, C) providing that the mattress 1. comprises higher plurality of groups of air cells (e.g. D. E - not shown). The particular design shown in Fig. 6 shows groups of air cells 3, 4 (B, C) as measuring air cells. When starting the process of inflation and deflation of air cells, these air ceils need to be loaded with a patient, i.e. the patient needs to be supported on a mattress 1_. The measuring air cells 3, 4 (B, C) are deflated to lower pressure, however not a zero pressure. The third group of air cells 2 (A, or plurality of other air ceils, depending on design of the mattress 1) is deflated to even lower pressure, being closer to zero pressure. Loading developed by a patient being supported on a mattress 1 generates change of pressure in the measuring group of air cells 3, 4 (B, C). This pressure change in the measuring group of air cells 3, 4 (B, C) is measured by control unit 12 as a pressure increase in the measuring group of air cells 3 (B), which is shown in the graph as Δ Pt (delta Pb)sand as a pressure increase in the measuring group of air cells 4 (C), which is shown in the graph as Δ Pc (delta Pc). The control unit 12 of the compressor 8 calculates a resulting pressure by sum of the pressure increase Δ Pb and Δ Pcin the measuring groups 3, 4 (B, C). The compressor 8 consequently adjust the resulting pressure in the 1.. Pressure profile in the individual groups of air cells A, B, C (2, 3, 4) is shown in the graph by curves A, B, C. The control unit 12 may repeat this process more times in cyclic according to patient's needs, or in compliance with the pressure change in any of the group of air cells A, B, C (2, 3, 4) sensed by and processed by control unit 12. also in cases when a patient is supported on mattress 1 for a long time (e.g. intensive care units) and weight of such patient changes in time due to weight loss and muscle loss, or fat gain and weight gain. The control unit 12 of the compressor 8 is capable also to detect change of a patient being supported on a mattress 1 and respond properly and fast by adjusting air pressure accordingly.

[0063] It is to be appreciated that the terms “include”, “includes”, and “including” have the same meaning as the terms “comprise", “comprises”, and “comprising”.

[0064] Several embodiments have been discussed in the descriptions. The embodiments discussed herein are not intended to be exhaustive. The terminology which has been used is intended to be in the nature of words of description rather than limitations

[0065] Abstract

[0066] This invention relates in general to medical patient support apparatuses having a mattress with air cells and a control unit adapted to adjust air pressure in the air cells of the mattress. Principal function of this invention described herein is an automatic pressure adjustment in the individual air cells depending on loading of these air cells developed by a patient being supported on a mattress.

Claims

CLAIMS1 . A method of automatic air pressure adjustment in a mattress (1 ) comprising groups of air cells (2, 3, 4) and a group of static air cells (5), wherein the individual air cells In one group are mutually connected by a pneumatic connection (7) and further are connected to a compressor (8) by a distribution unit (10) connected to a pump (11) and a control unit (12) being connected to at least one pressure sensor (9) characterized in that the control unit (12) inflates all groups of air cells (2, 3, 4, 5) to a preliminary defined pressure and consequently deflates at least one group of air cells identified as a measuring group of air cells to preliminary defined pressure and consequently deflates other groups of air cells to a pressure being close to zero pressure, except the group of static air cells (5), wherein the control unit (12) consequently detects a pressure increase in at least one group of measuring air cells, and whereas the control unit (12) consequently automatically adjust resulting pressure in all groups of air cells (2, 3, 4) in the mattress (1) depending on loading developed on the mattress.

2. The method of automatic air pressure adjustment in a mattress (1) according to claim 1 characterized in that the control unit (12) inflates all groups of air cells (2, 3, 4, 5) to a preliminary defined pressure and consequently deflates at least two groups of air cells identified as measuring groups of air cells to preliminary defined pressure and consequently deflates other groups of air cells to a pressure being close to zero pressure, except the group of static air cells (5), wherein the control unit (12) consequently detects a pressure increase in at least two groups of measuring air cells, and whereas the control unit (12) consequently automatically adjust resulting pressure in all groups of air cells (2, 3, 4) in the mattress (1) depending on loading developed on the mattress.

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