Multi-layered patient support cover system

In various embodiments, a support system includes a cover sheet with a number of layers. In certain embodiments, a top layer and a bottom layer are bonded to a middle spacer layer.

FIELD OF THE INVENTION

The present disclosure relates generally to support surfaces for independent use and for use in association with beds and other support platforms, and more particularly but not by way of limitation to support surfaces that aid in the prevention, reduction, and/or treatment of decubitus ulcers and the transfer of moisture and/or heat from the body.

BACKGROUND

Patients and other persons restricted to bed for extended periods incur the risk of forming decubitus ulcers. Decubitus ulcers (commonly known as bed sores, pressure sores, pressure ulcers, etc.) can be formed when blood supplying the capillaries below the skin tissue is interrupted due to external pressure against the skin. This pressure can be greater than the internal blood pressure within a capillary, and thus occlude the capillary and prevent oxygen and nutrients from reaching the area of the skin in which the pressure is exerted. Moreover, moisture and heat on and around the person can exacerbate ulcers by causing skin maceration, among other associated problems.

We wish to be able to manage larger quantities of body fluids including sweat, urine, wound fluids, etc., by improving the moisture management efficiency of a patient support cover sheet system such as Skin IQ™ product (which incorporates an electrically-powered fan to move air within an open layer beneath the patient) manufactured by Kinetic Concepts Inc. of San Antonio, Tex.

In a hospital environment, if a patient urinates on a cover, this has to be firstly detected by the caregiver, and the mattress cover changed. User experience with the Skin IQ™ patient support cover sheet indicates that an occasional urine leak can and will be managed via evaporation through the Skin IQ™ cover; however, if a significant quantity of fluid is involved, the patient is exposed to moisture for an extended duration during which there is increased risk of skin breakdown, where the duration of the moisture exposure depends upon the evaporation rate through the cover sheet system. By improving the fluid management efficiency of the cover sheet system, we not only reduce this skin breakdown risk and make it a product attribute, but we can also render the system more electrically efficient by maximizing the surface area which is exposed to airflow and moisture dissipation.

SUMMARY

Exemplary embodiments of the present disclosure are directed to apparatus, systems and methods to aid in the prevention of decubitus ulcer formation and/or promote the healing of such ulcer formation by managing patient skin exposure to moisture at the support surface cover sheet interface.

In various embodiments, a patient support system includes a cover sheet with a number of layers. In certain embodiments, the layers have different hydrophobic or hydrophilic properties and establish a fluid gradient to preferentially move fluid away from areas that contact a patient. Exemplary embodiments can also improve the net efficiency of the system by ensuring that the fluids are maximally exposed to the airstreams within the structure, and reduce the likelihood of fluid being held in dense local regions. In addition, exemplary embodiments overcome the challenge of having the majority of fluid pool in the area where there is the most compression of the structure (e.g., underneath the patient at contact pressure points). Exemplary embodiments also provide the ability to evaporate a bolus of fluid over a longer period of time, which can reduce air flow requirements and electrical power consumption by the patient support cover sheet system.

Exemplary embodiments can also provide a safety mechanism in that event that if air flow is interrupted for a period of time, e.g., if power is temporarily unavailable due to a power failure or the patient being moved to an area where power is not available. By moving the fluid away from the patient contact areas, the system can reduce the likelihood that the patient's skin will suffer negative effects such as decubitus ulcers, even without the benefit of air flow through the cover sheet system. By considering the hydrophobic/hydrophilic nature of each material in the structure and ensuring that there is in all cases a hydrophilic gradient away from the patient, the system can be configured such that moisture does not remain on the skin contacting layers.

In existing systems with multiple layers having similar hydrophobicity levels, the fluid will not flow from one into the other layer unless under the influence of an external stimulus. One objective of the disclosed system is to move the fluid into a place where it is maximally exposed to airflow such that the evaporation layer is able to release water molecules from the boundary layer of a material. As such, this becomes one end of the moisture gradient and any internal layers should not be more hydrophilic than the boundary layer effects of the system; otherwise, they will saturate with fluids and stall the transfer of moisture.

Exemplary embodiments have therefore established the two extremes required for the system: a first, very hydrophobic layer which is disposed to be in contact with the patient such that all fluids are encouraged to move under osmotic pressure into the device structure away from the patient skin; and further that any materials in the structure may not have an osmotic pressure which exceeds that of boundary layer effects noted in the previous paragraph.

In various exemplary embodiments, systems are provided that can include a number of components that both aid in prevention of decubitus ulcer formation and to remove moisture and/or heat from the patient. For example, systems can include a multi-layer cover sheet that can be used in conjunction with a variety of support surfaces, such as an inflatable mattress, a foam mattress, a gel mattress, a water mattress, or a RIK® Fluid Mattress of a hospital bed. In such exemplary embodiments, features of the multi-layer cover sheet can help to remove moisture from the patient and to lower interface pressures between a patient and the surface of the multi-layer cover sheet, while features of the inflatable or foam mattress can aid in the prevention and/or healing of decubitus ulcers by further lowering interface pressures at areas of the skin in which external pressures are typically high, as for example, at bony prominences such as the heel and the hip area of the patient. In other exemplary embodiments, systems can include the multi-layer cover sheet used in conjunction with a chair or other support platform.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

Exemplary embodiments of the present disclosure are directed to apparatus, systems and methods to aid in the prevention of decubitus ulcer formation and/or promote the healing of such ulcer formation. For example, in various embodiments, preventing ulcer formation and/or healing decubitus ulcers can be accomplished through the use of a multi-layer cover sheet. Exemplary embodiments of the multi-layer cover sheet can be utilized to aid in the removal of liquid, moisture vapor, and heat adjacent and proximal to the patient surface interface and in the environment surrounding the patient by providing a surface that absorbs and/or disperses the liquid moisture, moisture vapor, and heat from the patient. In addition, the exemplary embodiments of the multi-layer cover sheet can be utilized in combination with a number of support surfaces or platforms to provide a reduced interface pressure between the patient and the cover sheet on which the patient is positioned. This reduced interface pressure can also help to prevent the formation of decubitus ulcers.

In various exemplary embodiments, the cover sheet may include a number of layers. Each layer may be formed of a number of different materials that exhibit various properties. These properties may include the hydrophobicity level, the level of friction or shear of a surface, the permeability of a vapor, a gas, a liquid, and/or a solid, and various phases of the vapor, the gas, the liquid, and the solid, and other properties.

Exemplary embodiments can also improve the fluid management capability of the system through careful selection of materials, and by establishing a fluid gradient across the structure such that fluids are moved away from the patient to an area where they may be efficaciously evaporated.

Exemplary embodiments disclosed herein are tailored to have a hydrophobicity/hydophilicity gradient which is directed to ensure that fluids are preferentially inclined to move away from the skin/contact area whether under the influence of flows or fluid, or air.

Referring now toFIGS. 1-3, an exemplary embodiment of a cover sheet500is disclosed.FIG. 1illustrates a side view of cover sheet500during use and located between a patient180and a supporting mattress560.FIG. 2provides a top view of exemplary embodiments of cover sheet500(without patient180for purposes of clarity), whileFIG. 3provides a section view of cover sheet500taken along line3-3inFIG. 2.

The exemplary embodiments shown comprise an air permeable, water vapor-permeable first layer510, a second layer520, and a third layer530comprising a spacer material. It is understood that any of the individual layers may comprise a composite or laminate of multiple materials. As shown inFIG. 2, in this exemplary embodiment cover sheet500comprises a perimeter517with a first end502, second end504, first side506and second side508. Exemplary embodiments of cover sheet500also comprise a central region515surrounded by a perimeter region516, as shown inFIG. 2. It is understood that the rectangular shape of perimeter517shown inFIG. 2is merely one example of numerous configurations that are possible. Other perimeter shapes, including for example, oval, square, or other polygonal shapes are possible and included within the scope of this description.

In this embodiment, central region515generally comprises an area in the central portion of cover sheet500as viewed from above, and includes an area that will be in contact with and beneath a patient laying on cover sheet500during normal use. Perimeter region516extends around central region515and within perimeter517, and includes an area that will typically not be in contact with a patient laying on cover sheet500during normal use.

The general principles of operation for this exemplary embodiment are provided initially, followed by a more detailed description of individual components and principles of operation. In general, fluid116is transferred from a patient180, through first layer510and into second layer520, which distributes fluid116toward perimeter517before fluid116passes into third layer530. Fluid116may comprise perspiration (including both liquid and moisture vapor) during typical use. In addition, fluid116may comprise other fluids, such as urine, from patient180. As described in more detail below, during use air mover540pushes or pulls air through third layer530to facilitate the evaporation of fluid116. The movement of air within the cover system by air mover540, as well as the evaporation of fluid116, also transfers heat away from patient180.

In specific exemplary embodiments, first layer510is comprised of a highly hydrophobic material, while second layer520is comprised of a material that is more hydrophilic than first layer510, and third layer530is comprised of a material that is more hydrophilic than second layer520. Such a configuration can provide a fluid distribution gradient that promotes the movement of liquid away from first layer510and patient180during use.

In particular exemplary embodiments second layer520comprises fluid directional wicking properties such that when fluid116enters second layer520, it is wicked laterally toward perimeter517and away from the interface of patient180and first layer510. Such fluid movement can increase the exposure area of fluid116to both ambient airflows on first layer510and third layer530. In addition, the movement of fluid116toward perimeter517can move fluid away from central region515and into perimeter region516, which can reduce the fluid contact with patient180. This can in turn decrease the likelihood that patient180will develop complications such as decubitus ulcers associated with prolonged fluid exposure at the interface between patient180and cover sheet500.

In specific exemplary embodiments, second layer520may comprise a material such as Libeltex® TDL2, manufactured by Libeltex Group. This material has a two sided construction such that it will acquire fluids when one surface is exposed and, as the fluids permeate the material, the second side will use capillary action to wick or transport the fluids in a given direction.

In particular exemplary embodiments, third layer530comprises a spacer material of highly hydrophilic open-celled foam structure which serves as a manifold for fluid116from second layer520above into the foam structure, through which air is pushed or drawn for the purpose of evaporation. In certain exemplary embodiments, third layer530may comprise a spacer material of sintered polymers which do not collapse under the weight of patient180and also allow air flow through the material. Providing increased exposure of the hydrophilic area exposed to fluid116can improve the evaporation efficiency of cover sheet500. In specific exemplary embodiments, the thickness of second and third layers520and530can be approximately 0.125 to 0.025 inches. In other exemplary embodiments, second and third layers520and530may be either thicker or thinner than this range.

In certain exemplary embodiments, the cover sheet may comprise layers in addition to those described above. For example, a breathable absorption layer (e.g., a non-woven fiber such as a Libeltex Aerofill or a thin non-woven material deposited with an absorber) could be included between second layer520and third layer530. Such a layer could remain open to cover system air flows during low-moisture operation, and also to act as a reservoir in the instance that a larger volume of fluid were delivered than the evaporation process within the third layer530could manage. Such an embodiment could lead to the fluid being slowed on its progression through the structure, but would nonetheless keep the fluid away from patient180. In addition, certain exemplary embodiments may comprise a fourth layer (not shown) between third layer530and supporting mattress560.

First, second and third layers510,520and530are capable of being fixed together during manufacture through a variety of methods known to one skilled in the art, such as with adhesives, welding, quilting etc. The laminated structure is readily amenable to volume manufacturing methods, and the materials and processes are currently used in the medical industry and for furnishings in compliance with global safety standards.

In certain embodiments, various sensors could be integrated into or between one or more of first, second or third layers510,520, or530. In particular embodiments, the sensors can detect the presence of fluid, and the location of the sensors can be chosen to improve sensor performance and fan control system response.

In certain exemplary embodiments, air mover540can be a centrifugal 12 volt (nominal) DC fan manufactured by Panasonic under the part number FAL5F12LL. This particular air mover is approximately 3 inches wide by 3 inches tall by 1.1 inches thick and weighs approximately 3.5 ounces. This air mover also produces a maximum air flow of approximately 8.8 cfm and maximum air pressure of approximately 6.2 mm H2O at a nominal 12 volts. During operation, the air flow will be reduced as the pressure across the air mover is increased. Exemplary embodiments using this air mover typically have an air flow of approximately 1.0 to 2.0 cubic feet per minute (cfm) during operation. A graph of air pressure, air flow, and nominal speed for various voltages is provided inFIG. 4. As shown inFIG. 4, this air mover provides less than 6 mm H2O differential pressure at flow rates of approximately 2.0 cfm. The Panasonic FAL5F12LL air mover also creates low noise levels (30.0 dB-A, according to the manufacturer's specifications).

In another exemplary embodiment, air mover540is a 12 volt DC, 40 mm box fan such as a Sunon KDE 1204 PKBX-8. By utilizing an air mover such as the Sunon model (or other similarly-sized devices), air mover540can be placed integral to cover sheet500, allowing for a more compact overall design.

In one exemplary embodiment, first layer510may be comprised of a material that is liquid impermeable and air impermeable, but is moisture vapor permeable. One example of such vapor permeable material is sold under the trade name GoreTex.™ GoreTex™ is vapor permeable and liquid impermeable, but may be air permeable or air impermeable.

As used in this disclosure, the term “spacer material” (and related terms) should be construed broadly to include any material that includes a volume of air within the material and allows air to move through the material. In exemplary embodiments, spacer materials allow air to flow through the material when a person is laying on the material while the material is supported by a mattress. Examples of such spacer materials include open cell foam, polymer particles, and a material sold by Tytex under the trade name AirX™ Additional examples and features of spacer materials are disclosed in the description of third layer530inFIG. 3.

Referring back toFIG. 1, supporting mattress560and cover sheet500system provide support for person180and aids in the removal of moisture, vapor and heat adjacent and proximal the interface between person180and support system100. In the exemplary embodiment ofFIG. 1, cover sheet500comprises an integral air mover540. In other exemplary embodiments, air mover540may be external to cover sheet500with appropriate coupling members such as tubing, piping or duct work, etc. In certain exemplary embodiments, air mover540may comprise a guard or other partition (not shown) to prevent material from cover sheet500or the surrounding environment from blocking the inlet or outlet of air mover540. During operation, air mover540shown inFIG. 1operates to increase pressure within cover sheet500and create an air flow541that is pushed or forced through second layer520and into the surrounding environment.

In the exemplary embodiments shown inFIGS. 1-3, fluid116is transferred from person180(and the air adjacent person180) through first layer510and second layer520to air pockets within the spacer material of third layer530. Fluid116will continue to transfer to air pockets within spacer material while the air pockets are at a lower relative humidity than the air adjacent person180. As the relative humidity of the air pockets increases and approaches the relative humidity of the air adjacent person180, the transfer rate of fluid116will decrease. It is therefore desirable to maintain a lower relative humidity of the air pockets within third layer530than the relative humidity of the air adjacent person180. As fluid116is transferred to air pockets within third layer530, it is desirable to remove moisture vapor from the air pockets and lower the relative humidity of the air within third layer530. By removing fluid116from the air within third layer530, the transfer rate of fluid116from person180can be maintained at a more uniform level.

In the exemplary embodiment shown inFIG. 3, air flow541flows through the air pockets within third layer530and assists in removing fluid116from the air pockets. This lowers the relative humidity of the air pockets and allows the transfer rate of fluid116to be maintained over time. As shown inFIG. 3, air flow541from air mover540can be drawn (or forced) through the air space within third layer530. By distributing fluid116into a larger area toward perimeter517prior to entering third layer530, the amount of air flow541required for an effective moisture vapor transfer rate can be reduced as compared to systems that allow fluid116to enter third layer530in an area directly under person180.

The reduction in the amount of air flow541for a given transfer rate of fluid116can also reduce the size required for the air mover540. A decrease in the required air flow541can also reduce the amount of energy required to operate air mover540, thereby reducing operating costs. Reduced energy requirements and air flow541from air mover540can also reduce the amount of noise and heat generated by air mover540. A reduction in noise and heat can provide a more comfortable environment for person180, who may use cover sheet500for extended periods of time.

A reduction in the size of air mover540may also lead to a reduction in the cost of air mover540. In certain embodiments, the cost of air mover540may be low enough for air mover540to be a disposable item.

Support mattress560can be any configuration known in the art for supporting person180. For example, in certain exemplary embodiments, support mattress560may be an alternating-pressure-pad-type mattress or other type of mattress utilizing air to inflate or pressurize a cell or chamber within the mattress. In other exemplary embodiments, support mattress160does not utilize air to support person180.

The cover system can be placed on the person180to move fluid away from the skin, including above the person and without the inclusion of a support surface160. It is not necessary for the cover system to remain flat as suggested byFIGS. 1 and 3, although performance may be compromised by folds or creases that reduce air flow541.

As one of ordinary skill in the art will appreciate, vapor and air can carry organisms such as bacteria, viruses, and other potentially harmful pathogens. As such, and as will be described in more detail herein, in some embodiments of the present disclosure, one or more antimicrobial devices, agents, etc., can be provided to prevent, destroy, mitigate, repel, trap, and/or contain potentially harmful pathogenic organisms including microbial organisms such as bacteria, viruses, mold, mildew, dust mites, fungi, microbial spores, bioslimes, protozoa, protozoan cysts, and the like, and thus, remove them from air and from vapor that is dispersed and removed from the patient and from the environment surrounding the patient. In addition, in various embodiments, the cover sheet500can include various layers having antimicrobial activity. In some embodiments, for example, first, second and third layers,510,520and530can include particles, fibers, threads, etc., formed of silver and/or other antimicrobial agents. Antimicrobial agents can also be introduced into the air stream941, although distribution within the cover system would not be uniform.

In various exemplary embodiments, third layer530can be formed of various materials, and can have a number of configurations and shapes, as described herein. In some embodiments, the material is flexible. In such exemplary embodiments, the flexible material can include properties that resist compression, such that when the flexible material is compressed, for example, by the weight of a patient lying on cover sheet500, the flexible material has a tendency to return toward its original shape, and thereby impart a supportive function to cover sheet500. The flexible material can also include a property that allows for lateral movement of air through the flexible material even under compression.

Examples of materials that can be used to form third layer530can include, but are not limited to, natural and synthetic polymers in the form of particles, filaments, strands, foam (e.g., open cell foam), among others, and natural and synthetic materials such as cotton fibers, polyester fibers, and the like. Other materials can include flexible metals and metal alloys, shape memory metals and metal alloys, and shape memory plastics. These materials can include elastic, super elastic, linear elastic, and/or shape memory properties that allow the flexible material to flex and bend and to form varying shapes under varying conditions (e.g., compression, strain, temperature, ph, moisture, etc.).

In various exemplary embodiments, cover sheet500can be a one-time use cover sheet or a multi-use cover sheet. As used herein, a one-time use cover sheet is a cover sheet for single-patient use applications that is formed of a vapor, air, and liquid permeable material that is disposable and/or inexpensive and/or manufactured and/or assembled in a low-cost manner and is intended to be used for a single patient over a brief period of time, such as an hour(s), a day, or multiple days. As used herein, a multi-use cover sheet is a cover sheet for multi-patient use that is generally formed of a vapor permeable, liquid impermeable and air permeable or air impermeable material that is re-usable, washable, can be disinfected using a variety of techniques (e.g., autoclaved, bleach, etc.) and generally of a higher quality and superior in workmanship than the one-time use cover sheet and is intended to be used by one or more patients over a period of time such as multiple days, weeks, months, and/or years. In various exemplary embodiments, manufacturing and/or assembly of a multi-use cover sheet can involve methods that are more complex and more expensive than one-time use coversheets. Examples of materials used to form one-time use cover sheets can include, but are not limited to, non-woven papers. Examples of materials used to form re-usable cover sheets can include, but are not limited to, Gore-Tex®, and urethane laminated to fabric.