US 20100137775 A1
Disclosed herein is a device which is intended to deliver and maintain reduced pressure to body surfaces for application of reduced pressure wound therapy (RPWT) also known as negative pressure wound therapy (NPWT). During application of this type of therapy, a substantially airtight seal is formed around a section of tissue to be treated. This seal is formed by a dressing which provides fluid communication from a section of tissue to a reduced pressure source. Disclosed herein is a dressing system which is configured to enhance usability and functionality of this dressing. First, the system may be configured to allow full rotation of the fluid communication conduit to the reduced pressure source along the axis substantially normal to the dressing. Second, the system may be configured to include a one-way valve to prevent backflow of any drainage fluids. Third, the system may be configured with transparent windows covered by opaque flaps to allow inspection through the dressing. Fourth, the system may be configured to include an indicator which visually makes clear whether reduced pressure is being applied or not. Fifth, the system is configured to minimize the profile of the dressing system.
1. A reduced pressure treatment system, comprising:
a cover structure comprising an outer edge, an upper surface, a lower surface, and at least one opening;
a flowable adhesive layer attached to the lower surface of the cover structure, wherein the flowable adhesive layer has a thickness of at least about 0.2 mm; and
a non-electrically powered, self-generating vacuum source.
2. The reduced pressure treatment system of
3. The reduced pressure treatment system of
4. The reduced pressure treatment system of
5. The reduced pressure treatment system of
6. The reduced pressure treatment system of
7. The reduced pressure treatment system of
8. The reduced pressure treatment system of
9. The reduced pressure treatment system of
10. The reduced pressure treatment system of
11. The reduced pressure treatment system of
12. The reduced pressure treatment system of
13. The reduced pressure treatment system of
14. The reduced pressure treatment system of
15. The reduced pressure treatment system of
16. The reduced pressure treatment system of
17. A method for performing reduced pressure treatment of a skin location, comprising:
applying a dressing to a skin location;
applying a mask to the skin location, the mask comprising an inner edge and an outer edge;
applying a liquid sealant to the dressing and the skin location; and
removing the mask from the skin location.
18. The method of
selecting the mask to space the inner edge of the mask from the edge of the skin location.
19. The method of
20. The method of
placing a mesh material onto the liquid sealant after applying the liquid sealant to the dressing.
21. The method of
placing the mesh material onto the liquid sealant after removing the mask from the skin location.
22. The method of
placing a mesh material onto the dressing before applying the liquid sealant.
This application claims benefit under 35 U.S.C. §119(e) to U.S. Provisional Ser. No. 61/117,921, filed on Nov. 25, 2008, and to U.S. Provisional Ser. No. 61/117,920, filed on Nov. 25, 2008, which are hereby incorporated by reference in their entirety.
The use of sub-atmospheric pressure to treat wounds can be traced back to ancient civilizations. For example, the ancient Chinese used “Cupping,” a technique that creates reduced pressure environment by flaming then applying to the skin a glass chamber to draw out bad humors from the body. Modern research has revealed that applying reduced pressure to damaged tissue may have several beneficial effects: 1) a reduced pressure level may lead to retraction of the damaged tissue edges and thus may reduce the defect size and may expedite healing by facilitating wound contraction; 2) the reduced pressure may provide mechanical stimulation to the damaged tissue which may release growth factors at the wound bed to promote healing; 3) the reduced pressure may create suction in the damaged tissue cavity which may remove necrotic tissue from the damaged tissue cavity and may reduce bacterial load; 4) the application of reduced pressure may increase blood flow to the damaged tissue which may expedite healing; 5) reduced pressure may remove granulation inhibiting metalloproteinase enzymes which may enhance tissue remodeling and healing.
Disclosed herein is a device which is intended to deliver and maintain reduced pressure to body surfaces for application of reduced pressure wound therapy (RPWT) also known as negative pressure wound therapy (NPWT). During application of this type of therapy, a substantially airtight seal is formed around a section of tissue to be treated. This seal is formed by a dressing which provides fluid communication from a section of tissue to a reduced pressure source. The dressing system may be configured to enhance usability and functionality of this dressing, or to otherwise be configured with more optimal sealing characteristics, improved peri-wound skin protection, and with easier application than traditional RPWT dressing systems. In some examples, the dressing may comprise an adhesive layer comprising a flowable adhesive having a sufficient volume or thickness to fill micro-cracks and fissures in the skin surface to reduce dressing leakage rates, as well as gaps in the dressing that may form when the dressing buckles or wrinkles. The adhesive may also have moisture absorbent characteristics to reduce tissue maceration.
The dressing system may be configured with any of a variety of other features. First, the system may be configured to allow full rotation of the fluid communication conduit to the reduced pressure source along the axis substantially normal to the dressing. Second, the system may be configured to include a one-way valve to prevent backflow of any drainage fluids. Third, the system may be configured with transparent windows covered by opaque flaps to allow inspection through the dressing. Fourth, the system may be configured to include an indicator which visually makes clear whether reduced pressure is being applied or not. Fifth, the system is configured to minimize the profile of the dressing system.
In one embodiment, a reduced pressure treatment system is provided, comprising a cover structure comprising an outer edge, an upper surface a lower surface, and at least one opening, a flowable adhesive layer attached to the lower surface of the cover structure, wherein the flowable adhesive layer has a thickness of at least about 0.2 mm, and a non-electrically powered, self-generating vacuum source. The system may further comprise tubing configured to attach to the vacuum source. The vacuum source may be integrally formed with the cover structure. The cover structure may further comprise a port member attached to at least the upper surface of the cover structure. The flowable adhesive layer may comprise a moisture absorbent flowable adhesive layer. In some variations, the adhesive layer may have a water absorbency rate of at least 900 g/m2/day, 1000 g/m2/day, 1100 g/m2/day or 1200 g/m2/day or more. In some other examples, the flowable adhesive layer may have a thickness of at least about 0.3 mm, about 0.5 mm, about 0.7 mm, about 1 mm or at least about 1.5 mm. In some instances, the flowable adhesive layer may have a viscosity in the range of about 20,000 to about 50,000 centipoise, or about 10,000 to about 100,000 centipoise.
In another embodiment, a reduced pressure treatment system is provided, comprising a cover structure comprising an outer edge, an upper surface a lower surface, and at least one opening, a port member attached to the upper surface of the cover structure and comprising at least one port lumen in communication with the at least one opening of the cover structure, and a hydrocolloid layer attached to the lower surface of the cover structure, wherein the hydrocolloid layer has a thickness of at least about 0.2 mm. The hydrocolloid layer may comprise a reduced thickness region about the outer edge of the cover structure. In some examples, the reduced thickness region may comprise an embossed or compressed region, and/or may comprise an increased density relative to an interior region of the hydrocolloid layer. In some examples, the system may further comprise visual grid markings on the cover structure. In further examples, the port member may further comprise a base and a body configured to rotate with respect to the base. The base of the port member may be adhered to the upper surface of the cover structure. The system may further comprise tubing, the tubing comprising an outer wall, a proximal end, a distal end, at least one lumen therebetween, a longitudinal lumen axis, a first dimension transverse to the longitudinal lumen axis and a second dimension transverse to the first dimension and the longitudinal lumen axis. The tubing may also be configured to attach to the port member, or may be integrally formed with the port member. In some variations, the first dimension of the tubing may be greater in size than the second dimension, and in some variations, may be at least twice the size of than the second dimension, three times the size or four times the size or more. The tubing may also comprise a plurality of lumens in a generally planar configuration. In some examples, the at least one port lumen has a non-circular cross-sectional configuration, and may also comprise at least one lumen projection, which may be a plurality of longitudinal ridges. The tubing may also further comprise at least one side passageway providing communication between at least one lumen of the tubing and the outer wall. The system may also further comprise an elastomeric structure sealed to the outer surface of the tubing and covering the at least one side passageway, wherein the elastomeric structure may be a sleeve structure. In other examples, the elastomeric structure may be configured with an interior surface that is spaced a first distance from the outer wall of the tubing when the interior surface is exposed to atmospheric pressure and a second distance less than the first distance when the interior surface is exposed to a reduced pressure. In still other examples, the port member may comprise an elastomeric material. Sometimes, at least a portion of the elastomeric material may be configured to deform into the at least one port lumen when an internal pressure level within the at least one port lumen is at least about −50 mm Hg, about −75 mm Hg, about −100 mm Hg, or −125 mm Hg lower than atmospheric pressure. The cover structure may further comprise a reinforcement structure, which may be integrally formed with the cover structure. In some examples, the reinforcement structure comprises a first ridge structure on the upper surface of the cover structure and surrounding the port member. The system may also further comprise a second ridge structure surrounding the first ridge structure. The first ridge structure may be a segmented ridge structure. In some examples, the reinforcement structure may be embedded within cover structure.
The cover structure may also comprise a cover material and the reinforcement structure comprises a reinforcement material with an increased durometer than the cover material. The reinforcement structure may comprise a grid reinforcement structure, or a radial spoke structure. In some variations, the system may further comprise a release layer releasably adhered to at least a portion of the hydrocolloid layer. In some specific variations, the release layer may be releasably adhered to a central portion of the hydrocolloid layer, and the system may further comprise at least one or two handle layer(s) releasably adhered to at least a peripheral portion of the hydrocolloid layer and located between the hydrocolloid layer and the release layer. The system may also further comprise an adhesive carrier structure detachably attached to the upper surface of the cover structure. The adhesive carrier structure may comprise a first carrier layer and a second carrier layer and a non-linear interface therebetween. The adhesive carrier may also comprise a central opening surrounding the port member. The central opening may be spaced apart from the port member, and in some variations, may be spaced at least 1 cm from the port member. In some examples, the hydrocolloid layer may have a greater probe tack force about the outer edge of the cover structure than about an interior region of the cover structure. The hydrocolloid layer may also have a greater release force about the outer edge of the cover structure than about an interior region of the cover structure. In some instances, the maximum perpendicular dimension of the port member to the cover structure may be less than the maximum transverse dimension of the port member that is transverse to the maximum perpendicular dimension, or may be less than the maximum transverse dimension of the port member that is transverse to the maximum perpendicular dimension. The tubing may also further comprise a one-way check valve.
In another embodiment, a method for performing reduced pressure treatment of a skin location is provided, comprising applying a dressing to a skin location, applying a mask to the skin location, the mask comprising an inner edge and an outer edge, applying a liquid sealant to the dressing and the skin location, and removing the mask from the skin location. The method may also further comprise selecting the mask to space the inner edge of the mask from the edge of the skin location. It may also further comprise placing a contact material onto the skin location, wherein the skin location is an open wound, placing a mesh material onto the liquid sealant after applying the liquid sealant to the dressing, placing the mesh material onto the liquid sealant after removing the mask from the skin location, or placing a mesh material onto the dressing before applying the liquid sealant.
Application of reduced pressure to body sites has been shown to be therapeutically beneficial in several applications. One such area is the application of reduced pressure to damaged tissue such as chronic wounds in order to accelerate or promote healing. Regardless of the specific application area, application of reduced pressure requires formation of a substantially airtight seal.
In reduced pressure wound therapy (RPWT), a cover structure or dressing comprising an occlusive cover sheet with an adhesive layer is applied over the wound, which may be filled with a contact material such as gauze, foam or other porous materials, to provide cushioning and distribute the reduced pressure throughout the wound bed. The adhesive sheet may serve as a dressing and create a substantially airtight enclosure which encompasses the wound. This enclosure is in fluid communication with a reduced pressure source. The reduced pressure source may comprise an electric vacuum pump, in-wall suction, or a non-electrically powered suction device. The fluid communication between the vacuum source and the occlusive sheet is provided by a conduit which communicates with an opening in the occlusive sheet, or which passes through the dressing.
One of the major challenges in delivering RPWT is the application of the dressing and maintenance of a robust seal during treatment. Current techniques utilize thin polyurethane adhesive films that can easily wrinkle and fold onto themselves. These films frequently fail to remain airtight for a number of reasons, including mechanical deformation caused by patient movement and by the reduced pressure itself. The nature of the films, related to their mechanical characteristics and adhesive properties, make application difficult and time consuming. In addition, traditional dressings can be traumatic on removal to the delicate peri-wound skin and are not configured to treat smaller satellite wound lesions in the immediate peri-wound region of the main RPWT treated wound. Furthermore, there are locations with particular geometries that make application of a pre-fabricated dressing difficult and sometimes impractical, such as the bottom of toes.
For example, during the course of operation, reduced pressure applied to the dressing can lead to buckling of the dressing layer as it is drawn down over the contours to which it is adhered. For example a suction element attached to a dressing pulls on the surrounding dressing with application of reduced pressure and the contractile forces placed on the dressing can cause the dressing to buckle creating channels that radiate outward from the suction element attachment area. If these channels breach the dressing border, a leak path can form and compromise the desired seal. Dressing application can also lead to formation of wrinkles during handling and accommodation of anatomic curvatures. Healthcare practitioners frequently attempt to smooth out these wrinkles, but the properties of commonly used thin film dressing adhesives do not allow for sufficient filling of channels to close off leak paths that form and can be cumbersome to use. Therefore a need exists for an improved device and method of creating an airtight seal the wound site to which RPWT is to be applied.
In other general examples in wound care, transdermal drug delivery, and signal monitoring (i.e. EKGs), among other areas, the effective application of a dressing-type device or adhesive material to a body site may be complicated by the very aspects that lead to a high performance dressing once it is applied. Namely, pliable materials allow for a high degree of conformability to various body curvatures. Similarly, dressings that permit a fair amount of stretch accommodate natural body movement and flexion/extension motions. In combination with an appropriately adherent adhesive, these dressings can successfully stay on the body site for desired durations even under significant variations in external environmental conditions. Certain transdermal drug delivery patches, such as that by ORTHO EVRA®, are indicated to stay on for seven day durations while allowing normal daily activities as well as exercise including swimming. Successful application of these dressing systems can be confounded by the pliability that allows dressings to wrinkle and fold, particularly when the adhesive surfaces are exposed. Adhesive surfaces can often be difficult to separate once attached. Furthermore, highly stretchable materials may further exacerbate the situation because efforts to pull and separate material folds often leads to stretching of the dressing itself instead of the desired separation of self-adhered regions of the dressing. The quality of the adhesive can make it difficult to apply the desired surface to the body site as one's fingers may become stuck to the dressing surface.
On the other hand, while the adhesive strength of the dressing may be strong enough to prevent wrinkling or air channel leaks with movement, if the bond to the underlying skin is too strong, this can result in damage to the underlying skin upon dressing removal. This is especially true for patients with highly friable peri-wound skin which is common in many wound disorders such as venous stasis ulcers, traumatic wounds, diabetic ulcers, and pressure ulcers. Thus there exists a need to develop a RPWT dressing that optimizes adhesion for prevention of air leaks, but minimizes trauma from dressing removal to the underlying skin.
In some embodiments, the adhesive dressing material possesses improved crevice and leak channel filling and sealing properties as well as properties that protect and promote wound healing in the region around the treated wound. The dressing itself may have one or more specific properties that improve its ability to hold and maintain a seal and protect the peri-wound skin. Among these properties are (1) increased thickness of the dressing to facilitate placement and resist wrinkling that may lead to dressing wrinkling and seal leaks, (2) adhesion gradients on the undersurface of the dressing that allow for maximum sealing while maintaining minimum trauma to the peri-wound skin during removal, (3) adhesion strength characteristics that decrease over time to allow for strong sealing characteristics between dressing changes and easier and less traumatic removal of the dressing at the time period of dressing change, (4) a dual seal system with a thicker primary dressing and thinner peripheral dressing and backing system for simplified application, (5) a breathable dressing that prevents maceration of the underlying skin, (6) an absorptive dressing that prevents maceration of the underlying skin and promotes a moist wound healing environment for skin wounds around the central wound treated with RPWT, (7) support structures and thickness design elements that optimize rigidity and wrinkle protection while allowing for dressing conformation to a wound site, (8) a dressing configured such that upon activation the dressing flows and deforms to the body surface/skin contours to fill in potential leak channels, (9) a formulation such that the dressing can deform plastically such that stretching the dressing leads to a permanent deformation in the dressing enabling contouring of complex anatomical protrusions and intrusions with minimal elastic energy stored in the dressing layer, (10) a dressing system further configured to have sufficient rigidity to maintain its shape during application while remaining flexible enough to conform once applied to desired body topographies.
In some further examples, the dressing may be configured such that on activation the dressing flows and deforms to the body surface/skin contours to fill in potential leak channels. The adhesive layer of the dressing may comprise a semi-solid or flowable adhesive material. Some examples of such adhesives include but are not limited to hydrocolloid or hydrogel materials, silicone, pressure sensitive adhesives, and the like. In some specific embodiments, the adhesive material may be selected to have a glass transition temperature (Tg) that is at or near body core temperature (about 98.6° F.), room, temperature (anywhere from about 60° F. to about 90° F.) or body surface temperature (anywhere from about 70° F. to about 98° F., for example). In some variations, the Tg may be in the range of about ±1° F., about ±2° F., ±3° F., about ±4° F., about ±5° F., about ±6° F., about ±7° F., about ±8° F., about ±9° F., about ±10° F., about ±15° F., or about ±20° F. within body core temperature or a surface temperature about 60° F., about 65° F., about 70° F., about 75° F., about 80° F., about 85° F., about 90° F. or about 95° F. The adhesive dressing in one embodiment is also formulated to possess mechanical properties that allow it to flow and deform to fill paths or channels that may form during application and subsequent therapeutic use on a patient. This adhesive material may comprise a thicker acrylic adhesive, a hydrocolloid, a hydrogel or other such adhesive material without limitation. In some examples, the adhesive material may have a viscosity in the range of about 5,000 centipoise (cP) to about 500,000 cP, sometimes about 10,000 cP to about 100,000 cP, or other times about 20,000 cP to about 50,000 cP. In other examples, the adhesive material when subjected to low-frequency mechanical input (about <1 Hz) is selected to exhibit deformation properties and wear performance that may be characterized by a loss angle (tan δ) which equals the ratio of the loss modulus (viscous component) to the storage modulus (elastic component) of the tested material may be in the range of about 0.5 to about 2, sometimes about 0.5 to about 1, and other times about 0.5 to about 0.7.
In one configuration of the device the dressing is made of a hydrocolloid dressing that has some or all of the properties mentioned above, and/or one or more breathability, moisture absorbent abilities, skin protective properties, and wound healing characteristics. This dressing may also provide for a moist wound healing environment and is an appropriate dressing for satellite wound lesions. In one embodiment, the adhesive dressing may be formulated such that it flows on application of body heat and/or pressure to the dressing surface to eliminate potential leak channels that may form during application. In other embodiments, the application of light energy may also initiate a softening phenomenon to allow the adhesive to flow more readily and fill gaps.
In some embodiments of the sealant system, the film backing on which the adhesive layer resides is formulated to have desirable mechanical properties including elastic modulus and maximum elongation and stretch such that it is more compliant than the body site tissue it is adhered to in order to mitigate peeling and delamination of the dressing from the body surface. Having mechanical properties of the backing and adhesive layer tuned to be less stiff than that of the skin also leads to improved user comfort as the dressing material will not restrict movement. It is recognized that skin covering different areas of the body may have different mechanical properties, and the dressing's elasticity would be such that it would be able to accommodate the maximum possible stretch without applying excessive mechanical force on the underlying skin during normal distension. The dressing would also be flexible enough to conform to different geometries on the surface of the body. Some embodiments may be pre-shaped to provide optimal seal around irregular geometries such as around the toes or the sacral area.
In some embodiments, the dressing may be formulated to deform plastically such that stretching the dressing leads to a permanent deformation in the dressing enabling contouring of complex anatomical protrusions and intrusions with minimal elastic energy stored in the dressing layer. This stored elastic energy may tend to cause delamination of the dressing; so, its reduction may lead to better adherence of the dressing. This type of deformational plasticity might be highly useful in tailoring the dressing to regions like the foot or sacrum.
While some of the dressing application hurdles have been dealt with by others, in many cases, application of dressings is desired on different body sites. In some instances it is possible to make specific dressings for particular body sites to accommodate specific anatomy. However, even then, these dressings may not accommodate all anatomic variability and sometimes it is not practical to produce a dressing that will work for each possible anatomic location. Healthcare practitioners routinely find that certain dressings as received may not fit the needs of the patient and therefore proceed to cut or shape the dressing to fit the specific contours and body site requirements of the patient. This need for customization becomes particularly apparent with large dressings or body surface features with high curvature where folds and wrinkles can make good adhesion difficult. For transdermal drug delivery, proper adhesion dictates proper therapeutic drug dosing. In the case of signal monitoring, proper surface contact is critical. For RPWT, the quality of the seal around a wound site may be beneficial for maintenance of the reduced pressure, and leak paths can compromise therapeutic efficacy. The sealing properties of this dressing may be especially beneficial for RPWT devices that do not use a continuous electric pump or similar reduced pressure generation system, or otherwise have a limited suction capacity, as the tolerances for significant leaks is much lower than traditional RPWT devices. In many dressing systems, the dressing structures, such as release liners or handling flaps that permit easier application lose their functionality if the dressing must be shaped to fit a certain contour. Disclosed herein is a sealant system and method that mitigates formation of leak paths during and after application of said dressing by reducing folding of the dressing and adhesion of the dressing to itself or user while allowing simple dressing application to fit the needs of the individual after being cut to shape while possessing characteristics that permit the dressing adhesive to subsequently fill and close off channels that may form during or after the dressing application.
In addition, many wounds that may be treated by RPWT may have surrounding satellite wounds that are smaller and distinct from the central wound treated with RPWT. For example, patients with venous stasis ulcers often present with clusters of open skin areas. In addition, some wounds heal by skin bridging from epidermal migration across the wound. When this occurs, smaller proximal wounds can develop that are more near healing than other regions of the original wound. These types of satellite wounds may be too small to treat with RPWT, but may lie within the boundaries of where the dressing must cover to create a seal. Furthermore, many wounds are surrounded by highly friable and delicate skin that can be injured during frequent adhesive dressing removal. Traditional RPWT dressings do not address the needs of this peri-wound skin and satellite lesions, and there exists a need to develop a dressing that is both gentler to the peri-wound skin and may treat these satellite lesions with an appropriate dressing that promotes wound healing.
Furthermore, there are wounds that are located in regions of the body that using any type of pre-fabricated film would be difficult to apply. These regions might include wounds on the toes or fingers. Thus, there needs to be a dressing that can provide adequate sealing in these regions that can be tailored to the specific geometries of these locations.
The passage through the dressing is often times facilitated by a port feature on the top surface of the dressing. In the prior art, this port feature is fixed relative to dressing, which fixes the directional orientation of the fluid communication conduit once the dressing is adhered. In many applications, it may be advantageous to re-orient the fluid communication conduit direction after application of the dressing, since the user needs to account for the position and direction of the fluid communication conduit prior to and during application of the dressing. There exists a need for a port which allows re-orientation of the fluid communication conduit after application of the dressing without disrupting the dressing.
Wound drainage (e.g. exudates) is often times evacuated from the wound towards the reduced pressure source during the course of treatment of RPWT. If reduced pressure is interrupted or terminated, this drainage potentially may flow back into the wound, especially if the interrupted or terminated reduced pressure source is located at a higher elevation than the wound. Wound drainage may be contaminated with infectious microbes or compounds which are deleterious towards wound healing. Therefore, there exists a need to prevent wound drainage from flowing back to the wound in case of terminated or interrupted reduced pressure.
Use of a substantially opaque or aesthetically appealing dressing for RPWT may be advantageous, since it hides the wound and wound contact material from sight and may increase the psychological comfort of the patient and others. In some instances, it may also be advantageous to use a substantially transparent dressing, since clinicians may wish to inspect the wound, wound contact material or peri-wound skin without removing the dressing. Disclosed herein is a dressing which shields the wound from view normally, but also allows inspection under the dressing.
RPWT traditionally requires maintenance of reduced pressure at the wound bed for extended periods of time. It may be advantageous to have an indicator to show whether reduced pressure is present in the system or has been compromised, for example by a leak in the dressing. This may be particularly beneficial with closed system vacuum sources. Pressure indicators may include instrumentation such as dial indicators and pressure transducers. Often times, these may be large, bulky, require electricity or are expensive. Furthermore, often times, these indicators are located at the reduced pressure source and do not provide indication of the pressure at the site of the wound bed where its pressure information may be more useful. In case of disruption or clogging of the fluid communication conduit between the reduced pressure source and the dressing, these indicators may not detect that reduced pressure may be lost at the wound site but still present at the reduced pressure supply. There exists a need for a simple, inexpensive indicator to inform clinicians or patients whether reduced pressure is present at the wound or not.
Some of the wounds being treated with RPWT may be present due to tissue ischemia from pressure applied to a body site, e.g. decubitus wounds or pressure sores. To prevent or otherwise reduce the risk of continued degradation of the wound region and surrounding tissue, a low profile reduced pressure conduit that reduces concentration of force on the wound or surrounding tissue may be beneficial for proper therapeutic delivery of reduced pressure and for better wound healing. Current RPWT conduits often contain elements that can create additional pressure points over a wound if a load were to be applied onto the port component of the conduit. Disclosed herein is a negative pressure conduit that is low profile as to reduce the development of pressure points on the wound or surrounding tissues.
Disclosed herein are some embodiments of a device which enhance the functionality and/or usability of delivery of reduced pressure to body surfaces. One embodiment comprises a dressing, a fluid communication conduit and a port which allows passage of the fluid communication conduit from one side of the dressing to the other. The dressing may comprise at least one adhesive side which in practice may be adhered to a body surface to create a substantially airtight seal. The dressing and dressing adhesive may comprised polyurethane, hydrocolloid, hydrogel, silicone, acrylic, any other material or any combination thereof known in the art.
In some embodiments, the port is configured to allow at least some freedom of rotation around the axis substantially parallel to the plane of the dressing. In some embodiments, the freedom of rotation is provided by an o-ring seal and flange and groove system. In some embodiments, the port body comprises a substantially compliant elastomeric material bonded to substantially rigid elements which interact with substantially rigid elements on the dressing which together provide for substantially airtight seal of the rotational elements of the port. The port member may further comprise a connector configured to facilitate coupling to a fluid communication conduit that is then attached to the vacuum source. In other embodiments, at least a portion of the conduit may be integrally formed with the port member.
In some embodiments, the fluid communication conduit and/or port member passes through or transects the dressing and connects a sealed enclosure formed by the dressing with a reduced pressure source. In some embodiments, the fluid communication conduit comprises the port and tubing. In some embodiments, the tubing comprises a single lumen, while in other embodiments, the tubing may comprise multiple lumens.
In some embodiments, a one way flow mechanism may be interposed along the length of the fluid communication pathway between the dressing and the vacuum source. In some mechanisms, the one way flow mechanism is located in or integrated into the body of the port member, while in some embodiments, the one way flow mechanism may be integrated into the dressing or port-dressing interface. In still other embodiments, the one way flow mechanism may be located in or integrated into the tubing. In some embodiments, the one way flow mechanism may prevent or reduce the degree or risk of backflow of wound drainage collected by the reduced pressure source back to the wound. In some embodiments, the one way flow mechanism may be a one way valve, such as a duckbill valve, a slit valve, a spring valve, an umbrella valve or any other suitable one way valve known in the art. In some embodiments, a plurality of one way flow mechanisms may be interspersed throughout the fluid communication conduit. In further embodiments, the one way flow mechanisms may have non-uniform opening or cracking pressures to account for fluid pressure differentials from pressure head or flow rate.
In some embodiments of the device, the load concentration of the reduced pressure conduit and/or port member may be reduced during load bearing situations by reducing the height of the port and increasing its width. Reduction of load concentrations or pressure points may be further provided by the use of softer materials such as silicones or other materials known in the art to be able to deform under load. These materials may further be configured to possess similar mechanical properties as the skin such as durometer and elastic modulus. In some embodiments, the conduit in the port between the wound site and the tubing or reduced pressure source is reinforced with supports that prevent collapse of the conduit. In some embodiments, these supports are further configured to distribute loads applied to the device surface to reduce pressure concentrations. In some configurations of the device, the total cross-sectional surface area may be maintained relative to a round tube, but the height of the tubing (and thus nozzle) may be reduced by making the diameter wider and flatter to distribute loads more evenly. In addition, in certain configurations a multi-lumen conduit may be used to further reduce the external diameter and lower the profile of the nozzle and tubing.
In further configurations, the reduced pressure conduit may be integrated and potentially molded directly into the dressing material. In further embodiments, the reduced pressure conduit may be position through one or more openings or fenestrations of the dressing. In a further embodiment, the fenestration provides an insertion opening for an attachment port to connect a source of reduced pressure, or to connect an extension tube located on the outer surface of the dressing. In one embodiment, the reduced pressure conduit comprises a plurality of such fenestrations.
In one embodiment, the reduced pressure conduit or tubing comprises a hollow tubular structure which flares into and joins with the dressing material, enabling fluid communication between the volume beneath the bottom surface of the dressing and interior of the tubular structure. In one embodiment, the reduced pressure conduit is a resilient conduit embedded within the dressing with terminals connecting the bottom surface of the dressing and an attachment port on a side edge of the dressing. In one embodiment, the reduced pressure conduit is a series of such conduits.
In some embodiments, the reduced pressure conduit comprises a mechanism which allows quick attachment and detachment of the tube or reduced pressure source in an airtight manner.
In one configuration of the dressing, the dressing is integrated directly with the reduced pressure source and wound enclosure, e.g. a vacuum source attached directly to a port without an extension tube, and may also comprise further attachment of other portions of the vacuum source directly to the dressing to resist swinging or other motions of the vacuum source relative to the dressing. This eliminates may also reduce the need to puncture a hole and attach the vacuum source to the dressing, as required in some dressings, thereby mitigating application complexity, enabling successful application by non healthcare professionals and eliminating another potential source of air leak. In this configuration, the vacuum source does not employ tubing, but directly integrates into the dressing.
In some embodiments of the disclosed invention, the fluid communication conduit and/or the port member comprises a reduced pressure indicator. In some embodiments, the reduced pressure indicator is located in or along the conduit tubing. In some embodiments, the reduced pressure indicator is located within the port. In some embodiments, the reduced pressure indicator is integrated into the body of the port. In some embodiments, the reduced pressure indicator is comprised of a compliant material which visibly deforms when a pressure gradient is applied across it. In some embodiments, the pressure gradient leads a color change to indicate that the proper level of pressure application is achieved. For example, a sufficiently translucent or transparent blue element in proximity to a yellow material with the application of reduced pressure can effect a color change and appear green to indicate application or non-application of reduced pressure.
Various examples of the above embodiments are provided in greater detail below.
The dressing 101 also further comprises an adhesive layer located on the lower surface 107 of the dressing 101. In some embodiments, the thickness of the adhesive may be increased to facilitate placement and resist wrinkling that may lead to dressing wrinkling and seal leaks. In one embodiment of the dressing, the adhesive dressing thickness is increased to thicknesses substantially in the range of about 300 microns to about 10,000 microns or more, sometimes about 500 microns to about 2000 microns, and other times about 500 microns to about 1000 microns. Typical dressings used for RPWT may utilize thin relatively inelastic polyurethane film backings or facestock on the order of about 25 microns to about 50 microns in thickness with acrylic adhesive layers on the order of about 25 microns to about 125 microns in thickness. These thicknesses are demonstrably not sufficient in practice to easily create air-tight seals that last for about 4 to about 7 days. These thinner dressing may produce air leaks more often than when dressings with thicker adhesives were utilized. In addition, wrinkling with application of the thicker dressing was also reduced due to the increased rigidity afforded by the dressing thickness.
In some further examples, the adhesive layer material may be selected to provide an initial 90°-peel release force in the range of about 5N to 18N for a about 25 mm wide specimen. In some variations, the release force may be in the range of about 0.2N/mm to about 1.5N/mm, sometimes about 0.4N/mm to about 1N/mm, and other times about 0.5N/mm to about 1.2N/mm. The procedure for measuring the release force may be a standardized procedure, such as ASTM D3330, or other appropriate procedure. The adhesive layer may also be selected to provide a probe tack force property in the range of about 2.75N to about 5N with an initial loading of about 100 kPa, or other times in the range of about 2N to about 6N. The probe tack force may also be measured using standardize procedure, such as ASTM D2979, or other appropriate procedure. In some further embodiments, the adhesive layer may be selected to exhibit a decreased release force of about 20%, about 30%, about 40%, or about 50% or higher over a period of about 24 hours, about 48 hours, about 72 hours, or about 96 hours. In some instances, a reduced adhesive force over time may facilitate periodic dressing removal while reducing adhesive related damage to the surrounding skin.
In additional embodiments, fluid absorption of the dressing may be increased with adhesive material selection and thickness. For example, in some embodiments the dressing is composed of a hydrocolloid. In some examples, a different skin adhesive is provided around the edge or periphery of the dressing, while a hydrocolloid layer is provided on the interior region of the lower surface of the dressing. In other examples, however, the hydrocolloid may function both as a fluid absorption layer and an adhesive layer. The compositional properties and increased thickness of the dressing adhesive element allow for more capacity to handle fluid absorption, which may be beneficial in having a dressing that is functional in the presence of wound exudates and additionally promotes wound healing by maintaining a moist environment.
The dressing system may also comprise adhesion strength gradients on the undersurface of the dressing. In some examples, adhesive with higher bonding strength at the periphery of the dressing is provided compared to the central portion of the dressing. This is particularly important for RPWT treated wounds with fragile surrounding skin or smaller peripheral satellite wounds. Since the central portion of the dressing may be closest to the RPWT treated wound, the lower adhesive bonding properties of the central portion of the dressing may be less traumatic upon removal to the more delicate peri-wound skin and satellite lesions. The increased adhesive strength along the periphery may serve to maintain the integrity of a seal in a non-limiting manner by mitigating lifting of dressing edges, disruption from moisture (i.e. sweat, bathing, etc).
In further embodiments, a dressing with adhesion strength characteristics that decrease over time is disclosed to allow for sufficient sealing characteristics between dressing changes and easier and less traumatic removal of the dressing at the desired time of dressing change. In some embodiments, the dressing adhesive may have decreased bonding strength over time to allow for maximum adhesion during the period of treatment with RPWT between dressing changes, but weakened adhesion at the time of dressing change (typically in about 3 to about 7 days). This again allows for lesser trauma to the peri-wound skin during treatment. In some embodiments, the dressing is a hydrocolloid dressing that has weakening bond to the underlying skin with water absorption overtime. An indicator in the dressing may further indicate when the dressing should be removed and/or replaced. In additional configurations, the adhesive element may be deactivated or weakened with temperature, moisture, light, solution or other related modality that can weaken adhesive bonding.
A dressing with a thicker central dressing and a thinner peripheral dressing and backing system for simplified application is also disclosed. In this embodiment, a two seal system may be implemented to mitigate air leaks that may occur from the dressing to the wound bed in which a thicker dressing is bordered by a thinner dressing that extends around the edges of the dressing to create a secondary seal. In some embodiments, the central dressing may be made of a thicker hydrocolloid dressing and the peripheral dressing is a thinner polyurethane border with a stronger adhesive profile than the central hydrocolloid portion. The thinner peripheral second seal may help create a more resilient seal because the thinner portion of the dressing is less likely to curl or become mechanically disrupted than the thicker central portion. By combining the thicker and thinner dressings into a single dressing, the disclosed dressing captures the advantages of the thicker dressing as described above without the disadvantage of dressing edge curling and increased susceptibility to mechanical disruption. In addition, the second peripheral thinner dressing creates a second seal around the dressing that further mitigates the risk of air leaks in the dressing system. The use of adhesion gradients with the two seal system allows for robust seal at the edges with less traumatic removal to the peri-wound skin as well. In some embodiments, the dual-sealant system may possess two adhesive release liners. First, the central adhesive release liner is removed, and the dressing is placed on the patient. Next, the second release liner for the outer layer dressing, in some configurations a strip of liner along the dressing border, is removed after the central portion is adhered to create a secondary seal. In some embodiments, the double dressing has a peripheral portion of the dressing having a higher adhesive property than the central portion of the dressing to prevent the edges of the thicker central layer from curling up while minimizing trauma to the peri-wound skin.
An absorptive dressing is further disclosed that prevents maceration of the underlying skin and promotes a moist wound healing environment for skin wounds around the primary wound treated with RPWT. Disclosed herein is a RPWT dressing with moisture absorbent properties that augments wound healing conditions by reducing moisture build-up at the peri-wound skin and satellite lesions around the main lesion being treated with RPWT. This dressing in some embodiments is a hydrocolloid dressing or dressing with similar characteristics as a hydrocolloid. In some variations, the hydrocolloid layer (or other moisture absorbent material) may have an absorbency rate of about 900 grams/m2/day, about 1000 grams/m2/day, about 1100 grams/m2/day, about 1200 grams/m2/day, or about 1500 grams/m2/day or higher. The advantages of using an absorptive dressing as a dressing are that it can prevent maceration of the underlying skin, it is in contact with, and it can act as a good wound dressing for satellite lesions without the need for other secondary dressings underneath the dressing. In this embodiment the dressing itself may serve as the dressing for the peri-wound skin and peri-wound satellite lesions. The adhesive dressing disclosed in some embodiments may also contain therapeutic agents including drugs that facilitate healing or antimicrobial agents such as silver. One of the principles of modern wound therapy is the benefit of maintaining a moist wound healing environment. Thus, dressings for wounds that maintain a moist wound healing environment have become the mainstay of treatment for many types of wounds. Dressing such as alginates, hydrocolloids, and foams, all have absorptive properties that optimize the moisture levels of the underlying tissue for healing. Traditional RPWT dressings are not optimized for promoting healing of fragile peri-wound skin and satellite lesions. If the environment under the dressing near the underlying skin or satellite wounds is wet, it can lead to maceration of the underlying skin and wound edges. If the wound environment is dry, it can lead to suboptimal wound healing. A moist wound environment may be provided by moist gauze or other moist wound contact material. In some examples, the moist gauze is used in combination with a hydrocolloid dressing to provide a moist wound environment while wicking away moisture from the peri-wound skin.
A breathable dressing is disclosed that prevents maceration of the underlying skin. In some embodiments, the dressing will be configured to have a high enough moisture vapor transfer rate (MVTR) to allow for vapor loss that minimizes fluid collection over the peri-wound skin and the development of maceration of the underlying skin while at the same time maintaining a sufficiently strong seal to deliver RPWT. In one embodiment, the dressing comprises a hydrocolloid layer with an incorporated breathable component or construction. The hydrocolloid layer may be paired with a cover material that is also configured to wick away moisture, and in some variations, may have a MVTR of about 900 grams/m2/day, about 1000 grams/m2/day, about 1100 grams/m2/day, about 1200 grams/m2/day, or about 1500 grams/m2/day or higher. In some embodiments, the combination of moisture absorption and MVTR afford the dressing the ability to maintain desirable moisture content at the wound bed while reducing maceration and damage of peri-wound skin. In other examples, the dressing may comprise a single layer of hydrocolloid or hydrogel.
In some examples, the adhesive layer may be configured to mitigate pain and discomfort encountered by patients during the placement and replacement of reduced pressure therapy dressings. Damage to underlying tissue may also be reduced. The dressing may comprise an adhesive coating that creates bonding that is amenable to softening through a chemical reaction caused by application of a removal solution or hot air. In another embodiment, the adhesive coating may comprise a resin that softens when irradiated with ultraviolet (UV) radiation. Examples of a UV-softening adhesive include adhesives that have a bond which is broken by irradiation of an ultraviolet ray, such as CH, CO(ketone), CONH(amide), NH(imide), COO(ester), N═N(azo), CH═N(Schiff) and the like. An adhesive predominantly containing such a bond may be employed, for example a polyolefin adhesive such as a polyethylene adhesive or a polypropylene adhesive, a polyimide adhesive, a polyester adhesive, a polymethylmethacrylate (PMMA) adhesive and on the like. Also, an adhesive containing aromatic hydrocarbons (one or a plurality of benzene rings, or a fused ring thereof) in its structural formula may be employed. For example, some examples may employ an adhesive of a polyphenylenesulfide (PPS) adhesive, or of a polyethersulfone (PES) adhesive. Also, one or a combination of two or more of these materials may be employed. These adhesives may improve patients' quality of life as pain and re-injury during dressing changes would be mitigated and treatment time may be shortened. Finally, the adhesive coating may be pressure sensitive or otherwise formulated to permit long term robust adhesion to skin.
The treatment system 100 may further comprise a port 102 coupled to tubing 103 that provides a fluid communication conduit from underneath the dressing 101 towards a reduced pressure source (not shown). Port 102 may comprise compliant materials and a low vertical profile. In some examples, the low vertical profile comprises a maximum perpendicular dimension to the sheet material 101 that is smaller than a maximum transverse dimension to the maximum perpendicular dimension, an optionally transverse to the longitudinal axis of the tubing 103. In some examples, the maximum transverse dimension may be twice, three times, four times, five times, or six times or more greater than the maximum perpendicular dimension of the port 102. In examples wherein the port is integrally formed with the dressing materials, these dimensions may be measured from the plane aligned with the upper surface of the dressing.
In some examples, tubing may be attached or separated from the port using a connector fitting located on the port. The fitting may be configured to accept a cut tubing end, or may be configured to attach to a complementary end connector fitting that is attached to the tubing. In still other examples, the tubing may be integrally formed with the port. In still other examples, all or a portion of the port may further be configured to be detached and reattached to the dressing.
As depicted in
In the example depicted in
The flexible multilumen tubing 902 is shown to be lower profile and to permit alternate channels of reduced pressure communication with the wound and removal of exudates. The port material and tubing may be made of one or more compliant materials such as silicone or other thermoplastics elastomers (TPEs) known to those in the art that are moldable, extrudable or otherwise formable. In some variations, due to the smaller lumen diameters, capillary resistance may significantly impact the movement of liquid materials through the port and/or tubing. To reduce these surface interactions, the port and/or tubing may be treated with a lubricious coating, and/or may undergo surface modification procedures to alter the hydrophilicity or hydrophobicity of the native port or tubing materials. Such procedures are well known in the microfluidics area. To facilitate standardized connections to various vacuum sources, a multiple lumen to single lumen adapter or connector 908 may be provided to attach to regular tubing 909. The connector 908 may also be integrally formed with the multiple lumens 905 and/or the regular tubing 909.
In some embodiments, the dressing comprises transparent material in at least a partial section of the surface to allow inspection of the wound, wound contact material or peri-wound skin under the dressing. In some embodiments, the dressing further comprises flaps which may be reversibly adhered to transparent sections of the dressing. These flaps may be substantially opaque or appropriately colored to cover and hide the underlying dressing and general wound region. In some embodiments, the dressing comprises a singular flap. In some embodiments, the dressing comprises a plurality of said flaps.
In some further embodiments, a dressing application system or reduced pressure treatment system further comprises one or more applicator elements located above and/or below the dressing to support and facilitate the application of the dressing to the desired body site, and may also improve air-tight sealing of the dressing to the body surface. One potential function of these applicator elements is to ease application by providing sufficient rigidity to the dressing such that it does not easily fold and buckle and consequently stick to itself when the adhesive layer is exposed. Secondly, when the dressing is applied, the dressing system may be held and grasped while avoiding contact with the adhesive elements of the dressing to permit simpler application to the desired surface. Third, the dressing system is customizable to accommodate specific anatomical contours. When the dressing system is shaped, for example, by cutting the dressing system, the functional elements that permit simple application of the dressing to a wound site are preserved.
In some embodiments of the dressing system, the dressing system includes at least one support layer that maintains sufficient system rigidity once an adhesive surface is exposed while a secondary element to the dressing system comprises a layer or series of layers that shield the user from inadvertent contact with the adhesive components of the dressing prior and/or during application. These elements serve to alleviate the existing problems with dressing application that lead to poor dressing seating characteristics such as the presence of wrinkles due to buckling and resultant channels in the dressing. The embodiments described herein are directed toward more effective adhesion of a dressing to a desired body site.
In one exemplary configuration, the support layer is releasably attached or adhered to the facestock of the dressing and can be detached from the dressing once the user deems appropriate such as after the dressing has been secured to the body site. This support layer may comprise a stiff carrier element that may be configured to include break lines or folds that facilitate easier lifting up of an edge of the material for simple removal. The positioning and design of the break line is also such that cutting of the dressing to a smaller size allows the break lines to remain accessible. This carrier element may be clear or translucent to facilitate visualization of underlying components of the dressing system and the body site to which it is attached provided the dressing is sufficiently clear or translucent. A polyurethane or other similarly conceived material with sufficient rigidity may be used as a carrier element. In another exemplary configuration, a paper stock may be used with a weak adhesive to provide support to the dressing. The break line may be introduced by kiss-cutting an already adhered carrier film on top of the dressing or cut prior to application to the dressing. The carrier may also comprise at least one opening, or window, that allows direct access to the dressing, and may be configured such that a conduit (e.g. a port and/or tubing) can pass through it to permit communication of reduced pressure to the volume below the dressing. The location of the break line in the carrier film may also configured to allow for ease of removal when a reduced pressure conduit such as a port and attached tubing are present on the dressing.
In another embodiment, separate or in combination to the support layer are elements attached to the adhesive element of the dressing are release handles that mitigate user interaction with the adhesive during application to prevent inadvertent adherence of the dressing to the individual applying the dressing. These handles can take the form of coated polymeric sheets folded back on themselves to allow simple removal after initial adherence of the dressing to the body site. The release handles may be transparent or translucent to permit visualization through a clear or translucent dressing and carrier or opaque. The handles may be formed from a laminated sheet such as a silicone treated paper, fluorosilicone, or fluoropolymer treated film for example. The folds of the handles may be spaced sufficiently close to the center of the dressing such that the fold that is not adhered to the dressing remains present even when the dressing is cut to a smaller size for customization. At least one of these release handles is oriented along the dressing surface, typically along the perimeter of the dressing. For example, two sets of opposing release handles may be positioned in such a manner to cover the edges of a rectangular dressing. Another element may also be present to cover and protect the adhesive between the release handles prior to dressing application. This layer similar to the release handles may be transparent or translucent to permit visualization through a clear or translucent dressing and carrier or opaque. The release liner may be formed from a laminated sheet such as a silicone treated paper, fluorosilicone, or fluoropolymer treated film for example. With the upper support layer and lower release handles elements in place, the stiffening and adhesive shielding aspects of the two elements are preserved even with dressing shape customization.
Referring back to
For simplification purposes,
In further configurations of the device, reinforcements such as embedded rings or ridges may be incorporated into the dressing system. These structures or elements may streamline the application of reduced pressure dressings by mitigating buckling of the dressing and self-adherence of the dressing, and may also improve the ability of the dressing to form and maintain an airtight seal once it has been applied by reducing the wrinkling that may occur otherwise during application. In addition to dressing adhesive thickness, these elements may permit longer term delivery of reduced pressure to an area of tissue damage by providing a more robust seal with less ability to leak. Furthermore, the use of continuously running powered pumps to create reduced pressure may be obviated because the seal may be more robust than traditional RPWT dressings and may exhibit reduced or substantially no leakage. This type of treatment is less feasible using traditional reduced pressure sealant dressings.
To further augment the leak resistance characteristics of the reduced pressure treatment system, a spray-on, paint-on or otherwise initially fluid-based dressing may be utilized. In some embodiments a flexible and/or adjustable dam, stencil, mask or containment apparatus that may be placed around the treatment site. The dam may be configured in multiple sizes and/or shapes for specific anatomic locations and in certain configurations has a soft, bottom edge that can conform to multiple body location sites to form a near fluid resistant seal. In certain embodiments, the dam is further equipped with a mechanism to hold a RPWT conduit. In some embodiments, the dam may be further equipped with a holder for a RPWT dressing (foam or gauze, or other). Upon positioning the dam around the wound, the dressing, which may comprise any of variety of fast curing polymers or other similarly behaving materials, is sprayed or otherwise applied over the treatment site to create an airtight seal and enclosure around the site, the dressing, and portion of the conduit in fluid communication with the site. In certain embodiments, the applied substance may be a fast setting silicone or latex. In some embodiments, a RPWT conduit may be applied after forming the airtight enclosure with the applied dressing. In such an embodiment, the user may create an opening in the applied dressing in order to attach the conduit. The opening may be pre-formed during spraying or formed after spraying. In some embodiments, the conduit is attached to the airtight enclosure with an adhesive. In some embodiments, the applied dressing may shrink about 1% to about 10% or more in size as it cures to draw the wound edges inward to promote faster wound closure/wound healing. In other examples, a liquid dressing may be applied by brush, roller, or simply spread or squeezed over the treatment site.
It is to be understood that this invention is not limited to particular exemplary embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, some potential and preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. It is understood that the present disclosure supersedes any disclosure of an incorporated publication to the extent there is a contradiction.
It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a blade” includes a plurality of such blades and reference to “the energy source” includes reference to one or more sources of energy and equivalents thereof known to those skilled in the art, and so forth.
The publications discussed herein are provided solely for their disclosure. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided, if any, may be different from the actual publication dates which may need to be independently confirmed.
The preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims. For all the embodiments described herein, the steps of the method need not be performed sequentially.