FI89868B - STOEDSYSTEM FOER MINSKANDE AV UPPKOMSTEN AV LIGGSAOR - Google Patents

Abstract

A support system such as a clinical mattress comprises two sheets of flexible material bonded together to provide a plurality of separate cells (1) that are capable of being alternately and repeatedly inflated and deflated by means of a fluid contained in the cells (1). The flexible material is impermeable to the fluid. The cells (1) are of a size and shape and with an intercellular spacing such that in the width or length, or both, of the system, the distance between centres of adjacent inflated cells (1) is less than the human two-point discrimination threshold and the clinical support system is capable of supporting a human body with bottoming out either of or between the inflated cells (1).

Description

! 89868

This invention relates to a support system and similar devices for use in reducing skin collapse, and in particular to reducing the likelihood of bed sores in persons who are tied to a bed, wheelchair or the like for some time or who are otherwise completely or partially incapacitated.

10 As used herein, "support system" means mattresses, pillows, pillows and other similar support devices, including support systems that may be used for therapeutic or other purposes; 15 "bottom contacting" refers to both the collapse of a cell in a support system such that the top of the cell comes into contact with the underlying cell or bottom portion by a weight, e.g., a person's weight, and the person's contact with the bottom 20 cells of the support system; the "human two-point separation threshold" is measured from a person's back and is the smallest distance at which the contact of two objects can be distinguished when the objects are placed on the skin, that distance is known in anatomy and is approximately 30 mm in the back of 25 persons.

People may be tied to a support platform, such as beds, wheelchairs, or other devices, for a variety of reasons, such as injury or illness, or as a result of work-related job requirements. Older people may be tied to a bed or other equipment for extended periods of time.

Sleep ulcers, also referred to as pressure ulcers, pressure sores, or bed sores, are a prevalent problem in the health care industry, and incur high costs both in the form of human suffering and financial costs to society. The incidence of menstrual ulcers in hospital patients ranges from about 3% to about 17% and may increase to 20-30% in older hospital patients (D. Norton et al. An Study of Geriatric Nursing Problems in Hospital 5). treatment problems in hospital), Chur Chill Livingstone, Edinburgh (1962)). In neurologically impaired patients, the incidence may range from 30-60% of patients (Richardson and Mayer, Gerontol., 19, 235-247 (1981); Taylor, J. Gerontol. Nurs., 6, 10389-391 (1980)).

Bed sores are local cell deaths and tend to develop when soft tissue is squeezed between the protruding bone and the hard surface for long periods of time. External pressure acts to block blood flow, leading to ischemic damage. When blood flow and therefore oxygen supply is interrupted, a series of intracellular events occur that progress to an irreversible degree if blood flow is not restored. Ischemic damage results in cell death, i.e., necrosis, and the accumulation of cell debris within tissues.

The most fatal factors in the development of bed sores are the intensity and duration of the pressure applied, and the relationship between these factors has generally been believed to be a parabolic intensity-duration curve. If the patient 25 remains immobile and in the same position for less than about two hours, the ischemia is reversible and there is usually no long-term or irreversible damage to the soft tissues on the protruding bones, i.e., skin, subcutaneous tissue, and muscle. However, if the immobility time exceeds about two hours, bed sores begin to develop, which is sometimes referred to as the formation of first-degree pressure sores. It is for this reason that the principle of many hospitals and institutions is to change the position of patients approximately every two hours. However, this practice is not fully effective. In addition, the aim is to treat 3,898,68 patients at home rather than in hospital, and in such circumstances, nursing care is not available twenty-four hours a day.

Both external and internal factors are considered to have a detrimental effect on tissue pressure resistance. External factors that affect soft tissue include abrasion friction, humidity, and temperature. Internal factors that determine the susceptibility of tissue to collapse include loss of consciousness, impaired motility, old age, malnutrition, vascular disease, anemia, incontinence, and infections.

Age-related skin changes that may predispose older people to bed sores include: a flattened skin-epidermis junction (Montagna 15 and Carlisle, Journal of Investigative Dermatology, 73, 47-53 (1979)), decreased number of islets in Langerhans (Kripke, Journal of the American Academy of Dermatology, 14, 149-155 (1986)), impaired skin tightness, making the skin somewhat cell-free and vascular (Mon-20 tagna and Carlisle, ibid.), changes in connective tissue and elastic fibers (Shuster et al., British Journal of Dermatology, 93, 639-643 (1975)), impaired sweat and sebaceous gland function (Foster et al., Age and Aging, 5, 91-101 (1976)); Plewig and Kligman, Journal of Investigative Dermatology, 70, 314-317 (1978)), and impaired immune response (Barret et al., Clinical Immunology and Immunopathology, 17, 203-211 (1980)).

Versluysen (British Medical Journal (Clin. Res.), 292, 1311-1313 (1985)) reported that 90% of hip fracture patients over the age of 70 developed bed sores. Sleep ulcer healing has been associated with an almost six-fold higher mortality rate in the elderly (Reed, MD State Med. J., 30, 45-50 (1981)). Bedtime complications include myelitis and sepsis, and the mortality rate for sepsis is close to 50% (Galpin et al., American Journal of Medicine, 61, 4; 398 6 6 346-350 (1976); Sugerman et al., Arch. Phys. Med. Rehabil., 66, 177-179 (1985); Bryan et al., Arch. Intern. Med., 143, 2093-2095 (1983)). Thus, sleep wounds are a very serious problem in the healthcare industry.

5 Numerous systems are available to reduce the development of bed sores. Most of them operate on one of two principles, namely static devices such as foam mattresses, air mattresses, water beds and sheepskins that tend to redistribute support away from protruding bones, and active devices such as alternating air mattresses that operate by varying support pressure alternately. Although such devices are improvements over the use of conventional mattresses, additional heads are needed in terms of efficiency and / or efficiency of use.

Many static devices have only a limited service life because they cannot be effectively cleaned for reuse by the same or another patient.

A critical problem with active devices, and some static devices 20, is that they may not be able to carry body weight at the protruding bones. Under such conditions, the support system collapses under the weight of the protruding bone, and the bone ends up resting on the mattress below, i.e., it "touches the bottom." 25 This is the case regardless of the shape of the chambers, as such devices often consist of one or more air-filled chambers of expandable plastic material. The force exerted by the protruding bone on a relatively small area of the support device causes the portion of the air chamber 30 to collapse at it, since the rest of the air chamber only needs to expand slightly to equalize the pressure in the chamber.

Another concern is the shape of the air chambers. In most cases, the chambers are drawn into interlaced finger patterns of tubular or diamond or other shaped sections or cells so that when one section is filled with air.

5 ϋ 9 O 6 3 are adjacent periods empty. Typical support devices with cell sizes of 5 cm or larger have been unable to lift the patient clear enough from the mattress under the device to provide effective alternating pressure, especially for protruding bones.

Although the larger cells of some devices have sufficient range of motion, i.e., height, to overcome this bottom-contact problem (Bliss et al., British Medical Journal, 1, 394-397, (1967)), they have had other problems, such as large body areas. have been left unsupported, leading to patient discomfort and restlessness. Not even 5 cm cell sizes are able to prevent the small protruding bones of the body from falling between the swollen cells and resting on the underlying mattress, i.e. from touching the bottom. Although higher pressures can be used in such tubes to prevent bottom contact, there would be a comfort problem for the patient and no effective alternating pressures would be achieved. Another limitation of these devices relates to the period frequency, and more specifically to the time required to inflate the beneficial cells and empty the adjacent cells. The long swelling and emptying time prevents a sufficiently long pressure absence phase, i.e. an intermediate pressure below the internal capillary pressure, to allow normal blood flow and tissue recovery.

A support system has now been found that reduces the tendency to develop lunar ulcers.

Accordingly, the present invention provides a support system comprising: a plurality of discrete cells of a selected size and shape in a single layer, said cells being made of a flexible material; wherein said material is sufficiently dense with respect to the medium in said cells such that each cell can be alternately and repeatedly swollen and emptied; wherein said support system is capable of supporting the human body without contacting the base of said expanded cells or the base between said cells.

The invention is characterized in that (i) each cell (27) can be alternately and repeatedly swollen and emptied relative to an adjacent cell (11, 12), said cells being of such size and shape and their intercellular distance (d) being such that the distance between the centers of adjacent expanded cells in either the width or length of said support system is less than the human two-point separation threshold; (ii) when the support system supports the human body, the depleted cell applies a pressure less than the human internal capillary threshold.

In one embodiment of the support system according to the present invention, said cells are shaped and Kool-20 such that a weight of 2.5 kg with a spherical surface with a diameter of 2.67 cm when placed on the support system does not cause bottom contact of the support system.

The present invention also provides a support system comprising: (a) a system having a plurality of discrete cells of a selected size and shape in a single layer, said cells being made of a flexible material; wherein said material is sufficiently dense with respect to the medium in said cells so that each cell can be alternately and repeatedly swollen and emptied; said cells are of such size and shape and the distance between the cells is such that the distance between the centers of the adjacent expanded cells in either the width or the longitudinal direction of said system is less than the separation threshold of the two human points and said system is able to support the human body without , that this contacts the bottom of said expanded cells or the base between said cells, and 5 (b) means for expanding and emptying the cells.

In a preferred embodiment of the support system according to the present invention, said cells are shaped and sized such that a weight of 2.5 kg with a spherical surface of 2.67 cm in diameter when placed on the support system does not cause basic contact of the support system.

In another embodiment of the support system, the means for expanding the cells is controlled so that when one of the cells is expanded, the adjacent cells are emptied.

In additional embodiments of the support system, the cells may be inflated and deflated independently.

In still further embodiments of the support system, the cell expansion means is a compressor or a liquid which can be evaporated for cell expansion, in particular by using electric heating elements or thermoelectric means.

In another embodiment of the support system, each cell is shaped so as to prevent the complete collapse of the 25 cells when empty.

In addition, the present invention provides a support system comprising, in order: (a) a system comprising a plurality of discrete cells of a selected size and shape in a single layer, said cells being made of a flexible material; wherein said material is sufficiently dense with respect to the medium in said cells so that each cell can be alternately and repeatedly swollen and emptied; 35 said cells are of such size and shape and their intercellular distance is such that the distance between the centers of the adjacent expanded cells in either the latitudinal or longitudinal direction of said system is less than the human two-point separation threshold and said system is capable of supporting the human-5 body; without touching the bottom of said expanded cells or the base between said cells, (b) means for inflating and emptying said cells, (c) a layer of padding material, and (d) a layer of material having a high coefficient of friction.

In a preferred embodiment of the support system according to the present invention, said cells are of such shape and size that a weight of 2.5 kg with a spherical surface diameter of 2.67 cm when placed on the support system does not cause bottom contact of the support system.

In another embodiment of the support system 20, a layer of fabric, in particular a removable layer of fabric, is located on top of the flexible material layer, which fabric layer is between the moisture absorbing layer and the flexible material layer. The moisture absorbing layer is preferably a microporous film layer, more preferably a disposable layer.

The present invention further provides a cell which can be alternately expanded and emptied, said cell being formed of a flexible, dense thermoplastic material and containing an inert liquid having a boiling point of 30 to 0-50 ° C, and said cell further comprising means for heating and / or cool.

In a preferred embodiment of the cell according to the invention, the liquid is one or more fluorinated hydrocarbons, or one or more liquids of the type developed for environmental reasons to replace fluorinated hydrocarbons, in particular fluorinated hydrocarbons and 9 89868 liquids boiling in the range of 10 to 40 ° C. especially 20-34 ° C.

Although the present invention has been described herein with particular reference to clinical support systems and mattress support systems, it is to be understood that, especially in some applications, the system may not be in a form commonly referred to as clinical support or mattresses, but rather seat or other supports, as described below. .

The present invention will be described with particular reference to the drawings, in which Figure 1 is a schematic representation of a portion of one row of cells in a support system, all cells are shown in an expanded state, Figure 2 is a schematic representation of the cells of Figure 1, some emptied, Figure 3 is a schematic representation of the present invention. Fig. 4 is a computer simulated drawing of a cell, Fig. 5 is a bar graph of the results obtained in Example I, Fig. 6 is a graph of the results obtained in Example II, Fig. 7 is a graph of the results obtained in Example III, Fig. 8 is a graph of the results obtained in Example IV. pressure profile curve, Figures 9A and 9B are schematic sectional views of the use of support systems with elongated expanded tubular cells and support systems of the invention; Figure 10 is a temperature-recovery time curve measured in Example V; and Figure 11 is an example; VI measured curve of tissue thermal sensitivity over time.

Figure 1 shows a single row of cells 1; 39863 ίο The outer surface of the cells 1 and the substrate 2 are flexible sheets of material, and these sheets form the outer and bottom surfaces of the cells. The cells 1 are separated by spaces 3 which are substantially smaller than the distance d, 5 between the centers of the cells and are denoted by reference numeral 4.

Cells 1 are shown as elongated, but it is to be understood that the cells may be of any suitable type; nevertheless, the size and shape of the cells should be such as to prevent bottom contact, i.e. to prevent collapse of the cell in which the top of the cell comes into contact with the bottom of the cell under the influence of weight, e.g. the weight of the patient. An example of a cell is a computer simulated drawing shown in Figure 4. In use, the cells 1 would be connected to a means 15 for expanding and emptying the cells in a controlled manner; no such instruments have been presented. The cells may be made in one or more parts, including foams, provided that the cells can be expanded and emptied.

The cells 1 of Figure 1 are capable of swelling and depletion, as shown in Figure 2. In the illustrated embodiment, the expanded cells 11 are separated by empty cells 12. The distance between the centers of the expanded cells is less than the separation threshold of the two human points 25, and thus the person resting on the cells will not be able to feel that the alternating cells have been expanded and emptied. In addition, the patient is usually unable to sense the depletion of cells 11 and the expansion of cells 12.

In Fig. 3, the mattress system, generally indicated by reference numeral 20, consists of a closed cell layer 21, a fibrous layer 23 and a high friction layer 24 on top of the heating element layer 22. The closed cell layer 21 has a fabric layer 35 and a microporous outer layer 26. The closed cell layer 21 has a plurality of cells 27, which may be as shown in Figure 1. Cells 27 are shown elongate and parallel in both the longitudinal and transverse directions of the cells. However, the cells could be variable in shape and / or more irregular in Figure 5.

Cells are referred to herein as if they were "separate cells"; however, it is to be understood that although the cells appear to be discrete cells in physical appearance, any of the cells may be combined with one or more other cells for the purpose of expanding or emptying the cells.

Cells 27 are able to swell and deflate. Numerous devices can be used to swell and deflate cells. For example, the cells may be connected by a hose 15 to a device which alternately supplies a pressurized gas, e.g. compressed air, at a pressure sufficient to inflate the cells 27 when in use and then draw vacuum into the cells 27 to the extent necessary to empty the cells 27. The amount of vacuum to be generated may be small, for example just sufficient to empty the cells 27 to the extent that the cells 27 no longer support a patient resting on the mattress system 20. Compressors supplying compressed air tend to be noisy, and the supply of compressed air could alternatively take place at a location far from the area of use of the mattress system, such as a compressor or other source of compressed air. Alternatively, alternating pressure on the cells could be provided by hydraulic means to the fluid in the cells. Such liquids 30 include, for example, water and silicone oils.

The preferred method of expanding and deflating the cells 27 is to introduce fluid into the cells. When such a liquid is used, the liquid is heated, in particular by thermoelectric means, in order to cause steam 35 and thus the cells 27 to swell; such heating can raise the temperature of the liquid above its boiling point.

12 89 868 but it may not be necessary to do so, provided that sufficient pressure is created to swell the cells 27. Upon cooling, the pressure in the cells 27 decreases and the cells become empty. The fluid must be selected so that sufficient steam can be generated to cause the cells to swell, while maintaining the desired or preselected temperature. In addition, the fluid may need to be selected for a particular end use. For example, in some locations, the ambient temperature around the patient may be as low as 18 ° C, while in other locations, the ambient temperature may be as high as about 40 ° C.

The fluid introduced into the cells 27 is preferably inert, non-toxic and non-flammable, and is not a concern for authorities with respect to patients or persons caring for patients, such as doctors and nurses. In addition, the cells 27 must be made of a material having sufficient barrier properties with respect to the liquid so that the supplied liquid can be kept in the cells for at least the expected life of the mattress system; such material is referred to herein as impermeable. As described herein, the material may be a multilayer structure, including a coated structure, to achieve an acceptable level of tightness. It is to be understood that the assumed lifetimes of the clinical support system could be 6 months, or as long as 25 two years.

Cellular fluids include, for example, fluorinated hydrocarbons, especially mixtures of chlorofluorocarbons that change in vapor pressure over the temperature range used to expand and deflate cells 27, and media of the type developed to replace chlorofluorocarbons for environmental reasons, e.g., hydrochlorofluorocarbons. Fluorocarbons and hydrochlorofluorocarbons are sold by Du Pont Canada Inc. under the trademark Freon, 35 sold under the tradenames 114, 113, 22, 11, 123, and 141B.

13 89868

The boiling point of the liquid should be between 0-50 ° C, preferably 10-40 ° C. Liquids with boiling points at the lower end of this interval should be used, for example, to cool limbs or other parts of the body.

In certain embodiments, the boiling point of the liquid is in a comfortable range for the patient, but below the normal human sweat threshold, for example, between 20 and 34 ° C.

The cells 27 shown in Figure 3 are similar in that they may contain liquid. Although the fluid could be heated solely by the patient's body temperature, it is desirable that electrical or especially thermoelectric means be provided for heating and cooling the fluid. In Figure 3, the heating and cooling layer (thermoelectric layer) 22 located below the closed cell layer 21 has heating and cooling means 28 and 29 which can be used to evaporate or liquefy the liquid. Although reference is made herein to a heating and cooling layer, it is to be understood that in some embodiments, the layer may be exclusively a heating or cooling layer.

The heating and cooling means 28 and 29 are separate electrical circuits connected to adjacent cells 27, and the heating and cooling means 28 are used to heat and cool one of the 25 cells, and the heating and cooling means 29 are used to heat and cool the adjacent cell. One of the heating and cooling means 28 and 29 is normally connected to each cell so that the expansion and deflation of the cell 30 can be easily adjusted. Only two heating and cooling means 28 and 29 could be used to control the whole mattress system, or several heating and cooling means could be used to control different parts of the mattress system in different ways, for example using a microprocessor. It is preferred that the heating and cooling means operate at a low harmless voltage, i.e.

14 89868 at a voltage substantially below the voltage of the equipment normally used for heating and cooling.

As noted above, the flexible material must be sufficiently tight to allow the use of the clinical support system for the expected periods of use. The ability of a flexible material to meet such tightness requirements depends in particular on the fluid in the cells of the clinical support system. For example, flexible materials suitable for use with an inert gaseous medium, e.g., a hydrochlorofluorocarbon, may not be suitable for use when water is used, and vice versa, as will be appreciated by those skilled in the art. The flexible material is preferably a poly-15 polymeric material and especially a laminated, heat-sealed and coated polymeric material. In embodiments, the flexible material is a thermoplastic polymer laminated or coated with a polymeric material having barrier properties to the fluid in the cells of the clinical support system. In one embodiment, the polymeric material is linear low density polyethylene coated with or laminated with polyvinylidene chloride (PVDC). Such a flexible material has both barrier properties and flexibility and toughness properties that are important for the life of the clinical support system. In other embodiments, to the flexible material may be polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polyamide, chlorosulfonated polyethylene, vinylidene: 30 nifluoridiheksafluoropropyleenikopolymeereja, polyurethane ni, etyleenipropyleenidieeniterpolymeereja, copolyether-esteripolymeereja, silicone rubber, butyl rubber and natural rubber, coated if necessary to obtain the required barrier properties .

"35 The closed cell layer 21 and the thermoelectric layer 22 are shown on top of the fiber layer 15 89868 23 in Figure 3. The purpose of the layer 23 is to provide cushioning and good pressure distribution in the mattress system and thus make the patient feel more comfortable. The layer 23 can be made of several different fibers or foamed materials including synthetic fibers such as polyamide, polyester and / or polypropylene, natural fibers such as cotton, cellulose or wool fibers, including sheepskins, etc. In most cases, the fiber layer is formed of a synthetic fiber that is sufficiently airy to provide cushioning effects. polyester fiber used in the manufacture of the cushions In another embodiment, the layer 23 may be an air mattress.

Figure 3 shows the location of the fibrous layer 23 on the friction layer 24. The friction layer 24 is involved for patient retention and safety, especially in preventing the mattress system from slipping off the bed or other structure on which it can be used. Several friction layer materials are known, including foamed thermoplastic polymers such as poly-styrene, woven textile structures, Velcro® materials, and the like.

In the mattress system shown in Figure 3, two layers are placed on top of the closed cell layer. The layer 25 shown immediately adjacent to the closed cells is a fabric layer 25 which is primarily intended to be a cover layer or sheet enclosing the mattress system of the invention in order to maintain the integrity of the mattress system, and for aesthetic reasons ,::: 30 as well as for reasons of cleanliness and sterility to prevent infections. The outer layer shown is a microporous layer 26, which is primarily intended to make the patient feel comfortable. In particular, the microporous layer 26 allows sweating or other moisture associated with the patient to move away: "35 for the patient and improves patient comfort. The microporous layer is intended to be a disposable layer. The fabric layer 25 and the microporous layer 26 must be so thick and made of such materials that the beneficial effects of the function of the closed cell layer 21 are not negated.In an alternative embodiment 5, the outermost layer could be a non-stick layer, especially one used with burned patients or in some therapeutic applications.

When using the mattress system of Figure 3, the patient is placed on top of the mattress system, in contact with a layer placed on a microporous layer or sheet or a similar microporous layer. It is preferred that the mattress system be configured such that the cells are aligned directly diagonally with respect to the axis of the patient's body, and in embodiments positioned directly aligned transversely to the body. The cells of the closed cell layer are then swollen and deflated alternately, for example by heating using a heating element layer, and then allowing the liquid to cool or actively cooling the liquid.

The inflation and deflation period can vary from one minute to more than one hour. However, the period should be shorter than once every two hours. Periods of different lengths could be used in different areas of the body, for example, those areas where the body applies more pressure could have a shorter period than areas where there is less pressure, or different periods could be used for therapeutic or other reasons; it must be assumed that there are different optimum period times, depending on the intended use of the mattress system or clinical support system.

Here we are talking about the cycle time of cell swelling and emptying. The cycle time actually comprises the period of time required to move the medium out of the cell 35 or into the cell to effect actual expansion and emptying of the cell, or to liquefy or vaporize the medium completely inside the cell 17 β 9 β 6 8, as well as the period during which the cell is swollen or when empty. Such a medium transfer time is limited and can be minutes. It is to be understood that the beneficial effects of 5 cell depletion, especially the restoration of normal microcirculation in the skin layers at the depleted cell, are mainly limited to the period when the cell does not support the patient, which may be significantly shorter than the cycle time. The time required to move the medium 10 relative to the cycle time becomes more significant at short cycle times, and may need to be considered in the operation of the systems of the invention.

Expansion and emptying of cells is described herein in the general sense that when one cell is expanded, the adjacent cell is emptied. It is to be understood that such swelling and emptying may occur simultaneously or sequentially, the latter meaning that a cell is expanded and is followed by emptying of an adjacent cell. In addition, swelling and deflation may occur in wavy across the entire clinical support system, including the peristaltic period; in some cases, such a wave or peristaltic event may be sensed by the patient, but the event may, for example, have beneficial therapeutic effects and could be used for this or other reasons. In embodiments of the invention, the cell to be expanded is usually surrounded by depleted cells, and vice versa, or a row of cells may be expanded and the immediately adjacent row of cells emptied or other entities of expanded and depleted cells may be used, provided that the pool of expanded and depleted cells patient as described herein.

The mattress system of the present invention provides variable support to a patient in such a way that the patient 18 has little or no familiarity with the alternating support provided by the mattress system, i.e., parts of the patient's body are alternately supported and left unsupported so that the patient feels little or no movement in bed. 5 sa where he lies. Even the slightest feeling could be very worrying for the patient. But placing the expanded cells in at least one direction at intervals less than the human two-point separation threshold substantially eliminates or overcomes all kinds of sensations and allows the mattress system to perform its intended function. In addition, the pressure applied to the patient's body at the empty cell is less than the intrinsic human capillary threshold, for example 20 to 32 mm Hg; if this were not the case, there would be no blood circulation in a certain area of the patient's skin above the empty cells 15 and the result would be bed sores. Internal capillary pressure varies from patient to patient and probably from one area of the patient to another. The capillary pressure threshold, for example the surface pressure above which the capillaries can be expected to collapse, is about 20 to 32 mm Hg, depending on the area in each case in contact with the patient and the patient's mattress system. Thus, in embodiments, it is important that the pressure applied to the patient by the depleted cell is less than about 20 mm Hg; a more general requirement is that the pressure exerted through the emptied cells be less than the capillary pressure threshold.

As noted above, the clinical support system is capable of supporting the human body without the inflated cells touching the base or the substrate between the inflated cells. In one embodiment, the body is simulated on a spherical surface. In particular, the following procedure can be used to determine whether the support system is capable of supporting the human body without contact with the base: the method uses a clutch with a spherical surface with a diameter of 2.67 cm, the actual diameter of 35 heads being 7.5 cm. The radiator also has an arm which is connected to the end in the axial direction from the side opposite to the palpation, and the arm is such that weights can be attached to it. In the experimental arrangement, the cooler is placed on the surface of the cells in such a way that the cooler is located in the middle of the emptied cell and is supported by two adjacent expanded cells. Weights with an axial hole are then added to the shaker, using a rod, until the surface of the shaker touches the bottom surface of the emptied cell; at that time the total weight of the -10 si refrigerator should be at least 2.5 kg. Under such conditions, the cells and size of the support system would be such that a weight of 2.5 kg placed on the support system with a spherical surface of 2.67 cm in diameter would not cause contact with the bottom-15 of the support system.

Fig. 9A shows a part of the human body, generally indicated by reference numeral 40, shown on a mattress or paddle system 41 having large expandable cells 42, only one of which is shown sectioned. The expandable cell 42 is shown in contact with the base in the region 43, which is the cell region directly at the sciatic bone 44 of the torso 40. The gas in the expanded cell 42 is shown forced out of the region 43 in the direction of the arrows 45 where the cell has touched the bottom.

In contrast, Figure 9B shows the torso on top of the mattress system of the present invention. The mattress system consists of a single layer cell layer 46, the cells of which are shown alternately as expanded cells 47 and depleted cells 48. This cell layer is connected 30 to a flexible thermoelectric layer 49. The flexible thermoelectric layer 49 houses a series of heating and cooling circuits 50, each circuit 50 located in either an expanded cell. 47 or below the emptied cell 48; in the illustrated embodiment, the heating and cooling circuits 50 below the expanded cell 47 heat the gas in the cells, while the heating and cooling circuits 50 below the emptied cell 48 cool the steam in the cells. The flexible layer 49 is shown located on top of the fibrous layer 51. As illustrated in Figure 9B, the torso rests on the expanded cells 47 and is not depressed and does not touch the surface of the emptied cells 48. Thus, no pressure is applied to the torso above the emptied cells 48. Activation of the heating circuits below the emptied cells 48 and activation of the cooling circuits below the inflated cells 47 causes a change so that the part of the torso now shown to be in contact with the expanded cells becomes detached from the cells, and vice versa.

The mattress systems of this invention operate below both the capillary pressure threshold and the two-point separation threshold, thus providing the patient with the benefit of improved blood circulation and a reduced tendency to develop bed sores, while making the patient feel comfortable. The mattress system is easy to use, especially when a fluid capable of undergoing a change of state is used to swell and deflate the cells, it can be easily cleaned, and it operates quietly. In its embodiments, the mattress system could operate on a microprocessor and be portable, i.e., it can be applied to portable use, such as wheelchairs, and other mobile systems, and is also applicable to limbs and other body parts, allowing the patient to move. In addition, the fluid in the cells could be cooled to allow cooling of all or part of the human body, for example as a cooling wrap in surgery, or for therapeutic purposes.

Although the support systems of the invention have been generally described herein with reference to medical uses, i.e., as mattress systems, it is to be understood that the support system can be used in a variety of forms 21 39868 and for a variety of applications; in many such applications, systems would most often be referred to by other names, such as support systems, seats, chairs, and the like. For example, the systems described herein can be used in healthcare, transportation, and recreational activities that include aircraft, car, office, home, forklift, and other seats.

The present invention is illustrated by the following examples:

10 Example I

Holes of different cross-sections and different diameters were cut into a series of metal plates of different thicknesses. The diameters of the holes were as follows: 31.5 mm, 39.0 mm, 45.0 mm, and 51.3 mm. The thicknesses of the plates were 4.2 15 mm, 5.4 mm, 6.6 mm and 7.8 mm.

The subject's pelvis was placed alternately over each hole; the person was a healthy male, 46 years of age, 173 cm tall, weighing approximately 84 kg, and of normal construction. The pressure sensor was placed in the hole or on the opposite side of the hole so as to achieve the desired deviation. The sensor was on a wooden surface so that the pressure, if any, from the person to the device, i.e. in the plane of the opposite surface of the hole, could be measured.

The results obtained are shown in Figure 5. In only three cases did the human pelvis fail to apply pressure, i.e. touch the base, namely 31.5 mm in the hole with deviations of 6.6 mm and 7.8 mm (measured as the distance from the plate surface to the pressure sensor in the hole) and 39.0 mm in the hole with a deviation of 7.8 mm. Thus, at such holes-30 diameters and deviations, no ground contact was observed. Cells of this size and smaller in diameter would not result in basal contact of the pelvis of the human subject used in this example.

In a series of similar experiments, the 35 cell dimensions that would support the body in different positions were determined, for example, the sciatic bone in a sitting position, the larger horns lying on the side, and the sacrum and scapula in the crescent.

Such experiments provide an indication of what cell dimensions are required to prevent basal contact in the clinical support systems of this invention. The results obtained are different in different body positions.

Example II

Using the procedures described in Example I, with the exception that the holes were rectangular in shape, a series of experiments were performed on the effect of cell geometry on bone clot pressure. In all experiments, the thickness of the plate, i.e. its deviation, was 8 mm. The holes were aligned directly in the front / rear direction and had widths of 18 to 34 mm and lengths of 20 to 100 mm. The results obtained 15 are shown in Fig. 6. The same figure also shows a capillary pressure threshold of 32 mm.

Example III

Example II was repeated and holes placed in a straight line in the transverse direction were used. The results obtained 20 are shown in Figure 7.

It is found that the results of Example II show that where the longitudinal axes of the holes were aligned directly in the front / rear direction, only short cell lengths of 20-36 mm, with widths of 18-34 mm, yielded pressures below the Kapil-25 fluid pressure threshold. In contrast, the results of Example III indicate that much longer cells could be considered.

Example IV

The pressure exerted by the male person in the supine position with the mattress used in hospitals and the synthetic fiber layer on top of the mattress was measured at several points on both the mattress and the layer to describe the patient's pressure profile.

The results obtained are shown in Figure 8. The three high areas of body pressure were, in descending order, the buttocks, shoulders, and head. The use of a synthetic fiber layer on the mattress resulted in a substantial reduction in the applied pressure in the above areas, and that reduction was as high as 60% in the shoulder area, but the pressure was still of the order of magnitude above the capillary threshold in all three positions.

Example V

Using a thermal camera, the normal temperature of the skin of a person’s buttocks was observed after sitting in 10 positions of varying lengths. The person was a healthy male, aged 46 years, length 173 cm, weight approximately 84 kg and normal in structure. The subject sat on a soft pad or mattress system of the present invention operating for 10 min intervals several times and then monitored the time it took for his skin temperature to return to normal using an Agema infrared thermal imager, Model 870 with image analysis.

The results obtained are shown in Figure 10. Since the skin temperature is directly proportional to the blood flow in the skin, the return of the skin temperature to normal values is an indication of the state of blood circulation in the skin.

The results show that the recovery time increased exponentially with the length of the sitting period. In addition, the results show that recovery from 30 minutes of sitting on a mattress system according to the present invention is almost as fast as 5 minutes of sitting on a soft bed and significantly better than 7 minutes of sitting on a bed; it is noted that for 3 and 5 min with the bed and the mattress system according to the present invention. . The regression lines of the results obtained from 30 sitting have or tend to coincide at about 6 min, while the regression lines of the results obtained for longer periods of time for the patches show substantially longer recovery times.

For optimal performance, the recovery time to normal circulation in the depressurization step above the depleted cells of the mattress system of this invention should be consistent with the pressure endurance period of the inflated cells. The results show that the appropriate periodic frequency of the mattress system of the present invention in use by the person described above in a sitting position would be approximately 10 minutes.

Example VI

The recovery of skin temperature in the sacral region of a person after two hours spent lying down was monitored with an infrared camera. The subject was a healthy male, 10 at age 46, height 173, weighing approximately 84 kg, and normal in structure. The subject was placed in a supine position on a conventional hospital bed or on top of a mattress system of the present invention that operated for 10 min periods. After a two-hour period in bed or mattress, the subject was placed on his or her right side to immediately observe the sacral region using the thermal camera of Example V. The mean temperature change as a function of time relative to the subject's control temperature was measured. The results obtained are shown in Figure 11.

20 A thermal reaction after two hours in a hospital bed indicates erythema paratrimma, as indicated by a prolonged temperature rise relative to the control. Erythema paratrima is characterized by immediate reddening of the skin and an increase in temperature following the blocking cycle at pressure point 25. In contrast, after two hours spent on the mattress system of the present invention, the thermal reaction approached normal temperature after 15 minutes without signs of erythema paratrima.

Claims (18)

A support system comprising a plurality of individual cells of a certain size and shape in a layer wherein the cells are made of resilient material which is sufficiently tight relative to the medium of said cells so that the cells can be repeatedly repeated and expanded. is emptied, said support system being able to support a human body without affecting the bottom of said expanded cells or the bottom between said cells, characterized in that (i) each cell (27) can alternatively be expanded and emptied relative to to a neighboring cell (11, 12), said cells are of the size and shape of such and their intercellular distance (d) is such that either in the width or longitudinal direction of the support system the distance between the centers of adjacent expanded cells is less than the two-point threshold value of the human (ii) when the support system carries a human body, the emptied cell exerts a pressure which is is lower than the human capillary's internal capillary threshold. Support system according to claim 1, characterized in that said cells are of the size and shape such that a weight of 2.5 kg and of which the shape is round and the diameter of which is 2.67 cm, and which is placed on the support system , does not cause the upper and lower surfaces of the support system to touch each other. Support system according to claim 1 or 2, characterized in that the cells (11, 12) can be expanded and emptied independently. 4. Support system according to any of claims 1-3, characterized in that the liquid kp. is in the range 10 - 40 ° C. Support system according to any of the preceding claims, characterized in that it further comprises means for expanding and emptying the cells. 'J 9 8 6 8 29 6. Support system according to claim 5, characterized in that the means for expanding and emptying the cells are heating and cooling agents. Support system according to any of the preceding claims, characterized in that the medium is a gas. Support system according to any of claims 1-6, characterized in that the medium is a liquid. Support system according to any of the preceding claims, characterized in that each cell in its structure is such that it prevents the cell from completely collapsing when it is emptied. 10. Support system according to claim 9, characterized in that the expansion means of the cells are set so that when a cell is expanded, the adjacent cell is emptied. Support system according to any of the preceding claims, characterized in that the cells 20 are made so that they can be expanded and emptied within a period of less than two hours. Support system according to any of the preceding claims, characterized in that the distance between adjacent expanded cells is below 25 mm. Support system according to any of the preceding claims, characterized in that it further comprises a padding material; and a layer of a material having a high coefficient of friction. Support system according to claim 13, characterized in that the fabric layer has a fabric layer and said fabric layer is between the moisture-absorbing layer and the elastic material layer. Support system according to claim 14, characterized in that the fabric layer is a removable fabric layer. ϋ 9 Β 6 8 30 Support system according to claim 14 or 15, characterized in that the moisture-absorbing layer is a microporous film layer. 17. Support system according to claim 14, 15 or 16, characterized in that the moisture-absorbing layer is a disposable layer. A support system according to any of claims 5 to 17, characterized in that the means of expansion and emptying of the cells have a period which is such that it promotes the restoration of the normal microcircuit of the human skin where the cells are emptied.