Patent Application
20110208101
This disclosure relates to a compression dressing designed to provide moisture transport properties to a contact surface and compression therapy for patients with swelling due to various medical conditions. The compression dressing is minimally comprised of at least one layer of moisture transport fabric comprised of elastic fiber that exhibits a sufficient amount of elasticity to apply a compressive force to a body part when applied thereto. The compression dressing further provides one-way, active fluid management which can move fluid away from the skin. The compression dressing may also include at least one absorptive reservoir layer that is applied to the outer surface of the moisture transport fabric. This absorptive reservoir layer may be removed as needed without substantially disrupting the compressive force applied to a body part. The method for using the compression dressing to manage fluid movement and edema is also provided.
Current compression dressing systems frequently employ a skin-contacting absorptive layer or substrate which is capable of absorbing wound exudate or other fluids. The use of absorbent layers beneath compression dressings is well known and has been standard practice in the medical field for some time. A number of different absorptive systems can be employed based on the particular wound or medical condition or preference of a health care professional. For example, hydrogels, hydrocolloids, super absorbent polymers, ABD pads, gauze, cotton batting, foam and the like, have been employed for this purpose.
However, over the course of a single treatment as defined by the time between initial application of the compression dressing and the need for rewrapping (frequently seven days), the absorbent material may become saturated, leading to areas of maceration and damage of healthy skin tissue. Also, the retention of fluids within the dressing for such a long period of time can lead to unpleasant odors. Current compression systems also tend to become bulky or sag as they absorb fluid.
As one example, U.S. Pat. No. 5,939,339 to Delmore et al. teaches an absorbent, self-adhering elastic bandage with an integral absorptive component. The bandage is designed for use such that the absorptive layer of the bandage is in direct contact with a person's skin. The absorptive layer is integrally attached to the bandage and cannot be replaced when saturated with fluid. Rather, the entire bandage must be removed in order to replace the absorptive layer.
Similarly, U.S. Pat. No. 6,573,419 to Naimer discloses a compression dressing comprising a self-adhering elastic bandage strip designed for exerting a compressive force when wrapped around a body part. The compressive force is sufficient to hold the compression dressing in place for a period of time to provide a therapeutic effect to the patient. An absorbent pad is affixed to the skin-contact surface of the bandage. Thus, the absorbent pad cannot be replaced without removing the entire bandage and disrupting the compressive force previously applied to the body part.
Accordingly, there is a need in the medical field for a compression dressing which allows for an absorptive layer to be replaceable without disrupting the compressive force applied to a body part and, at the same time, manages the movement of fluid away from the skin surface which results in less surface wetness at the skin-to-compression dressing interface. Less surface wetness results in less skin maceration and/or better skin health. Additionally, swelling of the absorptive reservoir layer, which may occur as it absorbs fluids, would not detrimentally affect the overall shape of the compression system since the absorptive reservoir layer is located exterior to the moisture transport layer.
Thus, the present invention provides an improvement over the current compression dressing systems by allowing the patient and/or medical professional to replace the absorptive portion of a compression dressing system without substantially disrupting the compressive force applied to the body part wrapped with the dressing. In some cases, by allowing the patient to easily remove the outer absorptive reservoir layer when needed, without disrupting the moisture transport layer, time and expense associated with medical care for replacing soaked dressings may be desirably reduced. In some cases, as needed, more frequent changes of the absorptive media may occur, which may be beneficial for healing and/or for skin health at the skin-to-compression dressing interface. More frequent dressing changes may also lead to less odor build-up at the skin-to-compression dressing interface. For these reasons and others that will be described herein, the present compression dressing represents a useful advance over the prior art.
Provided herein is a compression dressing comprising the following sequential layers: (a) optionally, a skin-contacting layer; (b) at least one layer of moisture transport fabric comprised of elastic fiber, wherein the moisture transport fabric exhibits a sufficient amount of elasticity to apply a compressive force to a body part when applied thereto; (c) at least one absorptive reservoir layer; and (d) optionally, at least one layer of elastic fabric comprising the outermost layer of the compression dressing; wherein the compression dressing is at least 2 inches wide and 36 inches in length; and wherein the compression dressing provides one-way, active fluid management of fluid away from the skin and into the absorptive reservoir layer.
Also provided herein is a compression dressing comprising: at least one layer of moisture transport fabric comprised of elastic fiber, wherein the moisture transport fabric exhibits a sufficient amount of elasticity to apply a compressive force to a body part when applied thereto; wherein the moisture transport fabric is wrapped circumferentially and successively around a body part; wherein the compression dressing is at least 2 inches wide and 36 inches in length; and wherein the compression dressing provides one-way, active fluid management of fluid away from the body part and into the moisture transport fabric.
Also provided herein is a method for using a compression dressing in association with a body part, said method comprising the sequential steps of: (a) optionally, applying a skin-contacting layer onto or around a body part; (b) circumferentially and successively wrapping at least one layer of moisture transport fabric comprised of elastic fiber around the body part, wherein the fabric has a first skin-facing surface that is primarily hydrophobic in nature and a second non skin-facing surface that is primarily hydrophilic in nature; (c) successively wrapping at least one absorptive reservoir layer onto or around the body part; and (d) optionally, circumferentially and successively wrapping at least one layer of elastic fabric around the body part; wherein the layers of the compression dressing are at least 2 inches wide and 36 inches in length, and wherein the compression dressing provides one-way, active fluid management of fluid away from the skin and into the absorptive reservoir layer.
At various stages of venous diseases, such as varicose veins, chronic venous insufficiency, venous stasis, and venous reflux, different levels of compression ranging from 8-60 mm Hg are clinically indicated. According to Laplace's law, sub-bandage pressure is directly proportional to bandage tension, the number of layers applied, and inversely proportional to the radius of curvature of the limb to which it is applied. Laplace's law can be expressed as following equation,
wherein F is the tension of bandage, n is the number of layers applied, w is the bandage width, and R is the leg radius. Assuming that a bandage of standard width is applied in the form of a spiral with a 50% overlap to a patient with a leg (or other body part) of relatively fixed dimensions, bandage tension is the only variable in this equation, which illustrates the importance of this factor in the determination of sub-bandage pressure. The ability of a bandage to sustain a specific degree of tension is directly related with its elastomeric properties, as determined by fabric construction and finishing. The ability of a bandage to increase in length in response to an applied force is described as its extensibility, also known as percent strain or percent elongation.
As such, the Force of the bandage divided by the width of the bandage (F/w) is significant in applying the correct amount of pressure to the wrapped body part. This force is a function of the bandage extension or elongation and is tested using a tensile tester.
The next layer in the multi-layer compression dressing 100 is an absorptive reservoir layer 104 that exhibits high absorptive properties and acts as a fluid reservoir. Absorptive reservoir layer 104 may be comprised of any type of material capable of providing absorbent properties to the compression dressing 100. These absorptive materials include textile substrates (e.g., woven or knit fabrics, nonwovens, etc.), foam, hydrogel, hydrocolloid, superabsorbent polymers, silica gel, water swelling polymers, polysaccharides (e.g., chitosan, carboxymethylcellulose, hydroxylmethylcellulose, hyaluronic acid, alginates, pectin, etc.), proteinaceous materials (glycoproteins, gelatins, etc.) and the like, and combinations thereof.
The absorptive reservoir layer 104 of the compression dressing can exhibit any suitable absorptive capacity. For example, absorptive reservoir layer 104 may exhibit a fluid absorption of about 100 wt % or more based on the weight of the absorptive reservoir layer. In a specific embodiment, the absorptive reservoir layer may exhibit a fluid absorption of about 200 wt % or more, about 300 wt % or more, about 400 wt % or more, about 500 wt % or more, about 600 wt % or more, about 700 wt % or more, about 800 wt % or more, about 900 wt % or more, or about 1000 wt % or more based on the weight of the absorptive reservoir layer. The absorptive capacity of the absorptive reservoir layer may be measured by any suitable means. For example, the absorptive capacity of the absorptive reservoir layer may be determined by comparing the weight of the layer before and after immersing the absorptive reservoir layer in an aqueous solution of phosphate-buffered saline that contains 0.9 wt % sodium chloride at 37° C. until saturation is achieved.
The next layer in the compression dressing 100 is a moisture transport fabric layer 106 that exhibits the ability to move fluid, uni-directionally, away from the fluid source and into the absorptive reservoir layer 104. Moisture transport fabric layer 106 is comprised of any type of textile substrate capable of providing high wicking properties to the compression dressing 100.
Layers 104 and 106 may be independently comprised of textile substrates, such as fabrics, having a woven, nonwoven, or knit construction. Suitable knit textiles include, but are not limited to, weft-knit textiles, such as flat-knit textiles and circular-knit textiles. Fiber types comprising the textile substrate include synthetic fibers, natural fibers, and mixtures thereof. Synthetic fibers include, for example, polyester, acrylic, polyamide, polyolefin, polyaramid, polyurethane, regenerated cellulose (i.e., rayon), cellulose derivatives, and blends thereof. The term “polyamide” is intended to describe any long-chain polymer having recurring amide groups as an integral part of the polymer chain. Examples of polyamides include nylon 6; nylon 6, 6; nylon 1, 1; and nylon 6, 10. The term “polyester” is intended to describe any long-chain polymer having recurring ester groups. Examples of polyesters include aromatic polyesters, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), and polytriphenylene terephthalate, and aliphatic polyesters, such as polylactic acid (PLA). “Polyolefin” includes, for example, polypropylene, polyethylene, and combinations thereof. “Polyaramid” includes, for example, poly-p-phenyleneteraphthalamid (i.e., Kevlar®), poly-m-phenyleneteraphthalamid (i.e., Nomex®), and combinations thereof. Natural fibers include, for example, wool, cotton, flax, bamboo, and blends thereof.
The textile substrate may be formed from fibers or yarns of any size, including microdenier fibers and yarns (fibers or yarns having less than one denier per filament). The fibers or yarns may have deniers that range from less than about 1 denier per filament to about 2000 denier per filament or more preferably, from less than about 1 denier per filament to about 500 denier per filament, or even more preferably, from less than about 1 denier per filament to about 300 denier per filament.
Furthermore, the textile substrate may be partially or wholly comprised of multi-component or bi-component fibers or yarns, which may be splittable, or which have been partially or fully split, along their length by chemical or mechanical action. The fabric may be comprised of fibers such as staple fiber, filament fiber, spun fiber, or combinations thereof.
The textile substrate may optionally be colored by a variety of dyeing techniques, such as jet dyeing, vat dyeing, thermosol dyeing, pad dyeing, transfer printing, screen printing, flexigraphic printing or any other technique that is common in the art for comparable textile products.
A skin-contacting layer 110 is the next layer in the compression dressing 100 and forms the innermost layer of the compression dressing 100. The presence of skin-contacting layer 110 in the compression dressing 100 is optional. The skin-contacting layer 110 may provide anti-stick properties to the compression dressing such that its presence prevents the compression dressing from sticking to the skin and/or wound site. The skin-contacting layer 110 may also contain medicinal agents which aid in wound healing. Exemplary medicinal agents include, without limitation creams, ointments, balms, biologic scaffolds (e.g. collagen, modified collagen, extra cellular matrices, porcine sub-intestinal mucosa, and the like), skin grafts, and the like, and combinations thereof. Suitable materials for use as the skin-contacting layer 110 include textile substrates (e.g. fabric), foam, alginate, hydrogel, hydrocolloid, polymeric film (e.g. perforated polymeric film), and the like, and combinations thereof. Preferably, the optional skin contact layer 110 will not substantially impede or restrict the movement of moisture (e.g. wound fluid, sweat, and the like) into the successive layers of the compression dressing 100. In one embodiment, the skin-contacting layer 110 may be attached to the moisture fabric transport layer 106. For example, layer 110 may be laminated to layer 106 prior to application to a body part.
As depicted in
In certain embodiments, the surface energy of the first surface 112 of the moisture transport fabric layer 106 and the surface energy of the second surface 114 of the moisture transport fabric layer 106 can be substantially the same. In a specific embodiment, the surface energy of the second surface 114 of the moisture transport fabric layer 106 is greater than the surface energy of the first surface 112 of the moisture transport fabric layer 106. This difference in surface energies between the two surfaces means that the second surface 114 of the moisture transport fabric layer 106 exhibits a greater affinity for aqueous fluids (e.g., perspiration or wound exudates) than the first surface 112 of the moisture transport fabric layer 106. Thus, any aqueous fluids absorbed by the moisture transport fabric layer 106 will be transported or pumped from the first surface 112 to the second surface 114 of the moisture transport fabric layer 106. This active transportation or pumping of the fluids ensures that excess moisture does not accumulate at the interface of moisture transport fabric layer 106 and a moisture or fluid exuding surface, such as the skin or an exuding wound.
When the fluid transport layer comprises first and second surfaces having different surface energies, the difference between the two surface energies can be of any suitable magnitude. In a specific embodiment, the surface energy of the second surface 114 of the moisture transport fabric layer 106 can be about 101% or more of the surface energy of the first surface 112 of the moisture transport fabric layer 106. In more specific embodiments, the surface energy of the second surface 114 can be about 102% or more, about 103% or more, or about 104% or more of the surface energy of the first surface 112.
In addition to differences in surface energy, differences in capillarity can also yield desired fluid transport properties. As utilized herein, the term “capillarity” refers to the ability of a material to retain or expel fluid. In this regard, the capillarity of a material is determined by the pore size of the material as well as the contact angle with the fluid in question. Capillarity is measured by the ability of a material to either resist pressure when submerged to a given depth in an aqueous fluid or to draw aqueous fluid to a given height. Thus, the capillarity is the height of fluid drawn up (if positive) or height immersed (if negative) times the fluid density. The capillarity is defined by the following equation:
In this regard, the effective pore radius for a fabric with multiple pore sizes is generally dependent upon the character of the fabric. For materials that draw fluid inwardly, the effective radius tends to be dominated by the smaller pore sizes. For materials that expel fluid, the effective radius tends to be dominated by the larger pore sizes. As will be appreciated, in general, a positive capillarity will be associated with a generally fluid absorptive material while a negative capillarity will be associated with a material that expels fluid. As will be recognized by those of skill in the art, capillarity levels may be measured directly by using known techniques including wetting tests such as wicking and dewetting tests such as liquid extrusion porosimetry or porometry.
In one example, a jersey knit fabric comprised of predominantly polyester fiber on one side and nylon fiber on the opposite side may be utilized. The jersey knit fabric may be arranged such that the polyester side of the fabric contacts the moisture exuding surface (e.g. skin and/or wound), and the nylon side of the fabric contacts the absorptive reservoir layer 104. It may be generally known to those skilled in the art that a knit polyester fabric tends to be hydrophobic, slow to absorb liquids, and generally exhibits little or no wicking of moisture. Since polyester is hydrophobic in nature, conventional wisdom would lead one to choose a hydrophilic natural fiber, such as cotton, or a hydrophilic synthetic fiber, such as nylon, as the skin contacting side of the compression dressing. However, by placing a hydrophobic polyester containing surface toward the skin and a hydrophilic nylon containing surface away from the skin, a unique one-way, directional flow of fluid away from the skin was achieved.
As depicted in
In a specific embodiment of the moisture transport fabric layer 200 depicted in
An optional feature of the compression dressing of the present invention is that it may contain a topical coating of an antimicrobial agent, such as silver. It is known that placing surface-available silver in contact with a wound allows the silver to become absorbed by undesirable bacteria and fungi that grow and prosper in the warm, moist environment of the wound site. Once absorbed, the silver ions kill microbes, resulting in treatment of infected wounds or the prevention of infection in at-risk wounds.
The antimicrobial agent may include at least one silver-ion containing compound selected from the group consisting of silver ion exchange materials (e.g. silver zirconium phosphates, silver calcium phosphates and silver zeolites), silver particles (e.g. silver metal, nanosilver, colloidal silver), silver salts (e.g. AgCl, Ag2CO3), silver glass, and mixtures thereof. One preferred silver ion-containing compound is an antimicrobial silver sodium hydrogen zirconium phosphate compound available from Milliken & Company of Spartanburg, S.C., sold under the tradename AlphaSan® silver antimicrobial. Other potentially preferred silver-containing antimicrobials suitable for use herein—including silver zeolites, such as a silver ion-loaded zeolite available from Sinanen Co., Ltd. of Tokyo, Japan under the tradename Zeomic®, and silver glass, such as those available from Ishizuka Glass Co., Ltd. of Japan under the tradename lonpure®—may be utilized either in addition to, or as a substitute for, the preferred species listed above. Various combinations of these silver-containing materials may also be utilized.
Total add-on levels of silver to the target substrate may be in the range of 5 ppm to 20,000 ppm, more preferably 20 ppm to 20,000 ppm, and even more preferably 200 ppm to 20,000 ppm. Although these ranges are provided, an upper boundary limit of silver add-on levels to the target substrate may be limited only by consideration of the manufacturing economics of the product and by the potential to irritate a sensitive wound site, such that one would want to avoid excessive silver levels.
Preferably, the amount of silver-ion containing antimicrobial agent added to the moisture transport fabric layer should be such that moisture transport fabric layer is non-electrically conductive. “Non-electrically conductive” is defined as having a resistance in ohms per square inch of fabric of greater than about 10,000 ohms, preferably greater than about 100,000 ohms and most preferably greater than about 1×109 ohms, when measured in accordance with AATCC Test Method 76-1978.
The antimicrobial agent applied to the moisture transport fabric layer may also comprise non-silver compounds. These include, for example, compounds that contain copper, zinc, iodine, triclosan, polyhexamethylene biguanide (PHMB), N-halamines, chlorhexidine, quaternary ammonium complexes, and mixtures thereof, as well as common antibiotic pharmaceutical compounds. It is also contemplated that non-silver ion containing compounds may be combined with silver-ion containing compounds to form the antimicrobial agent.
Generally, the antimicrobial agent is added to the compression dressing in an amount from about 0.01% to about 60% by total weight of the particular finish composition; more preferably, from about 0.05% to about 40%; and most preferably, from about 0.1% to about 30%. The antimicrobial finish may include other components such as binder materials, wetting agents, odor absorbing agents, leveling agents, adherents, thickeners, and the like.
The inclusion of a binder material with the antimicrobial agent has been found useful in preventing the antimicrobial agent from flaking onto and/or into the wound that is being treated. Preferably, this component is a polyurethane-based binder material, although a wide variety of cationic, anionic, and non-ionic binders may also be used, either alone or in combination. Specific examples include nonionic permanent press binders (e.g., cross-linked adhesion promotion compounds, including, without limitation, cross-linked imidazolidinones available from Sequa under the tradename Permafresh®) or slightly anionic binders (including, without limitation, acrylics such as Rhoplex® TR3082 from Rohm & Haas). Other nonionics and slightly anionics are also suitable, including melamine formaldehyde, melamine urea, ethoxylated polyesters (such as Lubril QCX™, available from Rhodia), and the like. Preferably, the binder material is biocompatible such that it does not cause negative reactions in the wound. In essence, the binder materials assist in adhering the antimicrobial agent to the surface of the target substrate, such as fibers or fabrics, without negatively affecting the release of silver ions to the wound.
One exemplary acceptable method of providing an antimicrobial silver-treated fabric surface includes the application of a silver ion-containing compound and polyurethane-based binder resin from a bath mixture. This mixture of antimicrobial compound and binder resin may be applied through any technique as is known in the art, including spraying, dipping, padding, foaming, printing, and the like. By using one or more of these application techniques, a fabric may be treated with the antimicrobial compound and binder resin on only one side of the fabric, or it may be treated on both sides of the fabric. Methods of topically applying a silver-based antimicrobial finish to textile substrates are described, for example, in commonly assigned U.S. Pat. Nos. 6,584,668; 6,821,936; and 6,946,433 and in commonly assigned U.S. Patent Application Publication Nos. 2004/0106340 and 2004/0106341. All of these patents and patent applications are hereby incorporated by reference.
In
The production process for making the compression dressing of the present invention may include bringing together the various layers of the pad, such as from rolled goods; cutting the layers into the desired shape; and combining the layers together for use, such as by sewing or thermal sealing of the edges, to yield a finished, properly dimensionalized product.
Alternatively, the layers could be laminated together at wide widths, as the layers are taken from the rolled goods, and then the laminated layers may be cut into the properly dimensionalized product. For instance, the compression dressing may be characterized by having dimensions that are at least 2 inches in width, at least 3 inches in width, at least 4 inches in width, or at least 5 inches in width. Further, the compression dressing may be characterized by having dimensions that are at least 36 inches in length or at least 48 inches in length. These dimensions may be mixed and matched in any manner to achieve a compression dressing that is characterized by having dimensions of width and length most suitable for treating a given medical condition. It may be preferable that the compression dressing is characterized by having dimensions that are at least 2 inches wide and 36 inches in length. The compression dressing may further be characterized by having dimensions that are at least 4 inches wide and 48 inches in length. It is contemplated that each finished product will be individually packaged in standard medical packaging material and then sterilized, such as by gamma irradiation.
Each of the layers comprising the compression dressing of the present invention is arranged substantially coextensive with each another. The layers of the compression dressing may be affixed to each other, or joined together, by any conventional process. For example, the layers may be joined by using adhesives, by sewing the layers together, via thermal sealing of the edges, by spot lamination, by ultrasonic lamination, and the like, and combinations thereof.
The compression dressing may also be secured in place during use (e.g. in association with a body part) by a variety of attachment means. Suitable attachment means include any implement that is capable of securing the compression dressing in place, when in association with a body part. Exemplary attachment means include clips, pins, adhesives (e.g. tape, liquid adhesives, etc.), loop and hook closures, zippers, buttons, snaps, self-adhering coatings, and the like, and combinations thereof.
The compression dressing may also be utilized as a drug delivery apparatus by incorporating certain compounds into one or more layers of the compression dressing which may be released for use in or on a patient. For instance, these compounds may include antibiotics, pain relievers, peptides, growth factors, anti-inflammatory agents, enzymatic or other debriding agents, and the like, and mixtures thereof.
Other additives may be present on and/or within the fabric or yarn comprising the compression dressing, including antistatic agents, optical brightening compounds, opacifiers (such as titanium dioxide), nucleating agents, antioxidants, UV stabilizers, fillers, permanent press finishes, softeners, lubricants, curing accelerators, adhesives, and the like. The layers comprising the compression dressing may also be coated or printed or otherwise aesthetically modified. Printing may be achieved, for example, by screenprinting or flexographic printing techniques.
The compression dressing itself may further include additional additives as needed for desirable end-use attributes. One exemplary additive includes superabsorbing polymers such as polyacrylic acid, polyacrylamide-containing polymers, polyvinyl alcohol, and the like, and mixtures thereof.
The compression dressing may be of any thickness, depending on the construction of the fabric and the desired level of padding and/or absorbency needed. It may, however, be preferred that the thickness of the compression dressing is between about 0.0625 inches and about 2 inches, more preferably between about 0.125 inches and about 0.5 inches.
An additional advantageous feature of the compression dressing of the present invention is its ability to substantially maintain its original color when effective amounts of a silver-ion containing antimicrobial agent are included in the dressing. The elimination of color normally associated with the inclusion of silver-based antimicrobials is highly beneficial and desirable. The compression dressing (preferably, white-colored) allows users thereof and their health care providers to monitor the exudates from a wound. Further, the compression dressing generally exhibits long-term color stability (that is, the color does not change significantly over time while in production, transit, or storage). Finally, because the compression dressing is not discolored by the addition of the silver-ion containing antimicrobial agent, a variety of substrate colors may be utilized. Colored substrates may be achieved by dyeing or coloring to any desired shade or hue with any type of colorant, such as, for example, pigments, dyes, tints, polymeric colorants, and the like.
Methods for use of the compression dressing of the present invention in association with a body part dressing include the steps of (a) applying a skin-contacting layer onto or around a body part; (b) circumferentially and successively wrapping at least one layer of moisture transport fabric comprised of elastic fiber around the body part, wherein the fabric has a first skin-facing surface that is primarily hydrophobic in nature and a second non skin-facing surface that is primarily hydrophilic in nature; (c) successively wrapping at least one absorptive reservoir layer onto or around the body part; and (d) circumferentially and successively wrapping at least one layer of elastic fabric around the body part. Steps “a” and “d” are optional. The layers of the compression dressing should be at least 2 inches wide and 36 inches in length. Additionally, the compression dressing should provide one-way, active fluid management of fluid away from the skin and into the absorptive reservoir layer. The layers comprising the compression dressing are preferably applied sequentially as described above. This method may be ideal for use in reducing edema in a body part. Each layer present in the compression dressing may be wrapped circumferentially and/or successively around the body part as desired for the specific medical condition to be treated.
The amount of compressive force provided by the compression dressing, when applied to a body part, is directly related to the resistive force of the material at a given strain and can be expressed in units of pounds force (lbf) per inch width of material. Typically, compression layers are applied at approximately 50% strain. In order to achieve acceptable levels of compression, the material will preferably exhibit a resistive force from 0.05 to 2.0 lbf per inch width at 50% strain, more preferably 0.07 to 1.0 lbf per inch width at 50% strain, and even more preferably 0.1 to 0.6 lbf per inch width at 50% strain. However, the exact amount of compressive force applied to a body part by the dressing of the present invention may depend on the body part being wrapped, the specific medical condition being treated, and application technique.
Additionally, when the absorptive reservoir layer is removed from the compression dressing, the moisture transport layer will preferably continue to provide a compressive force to the body part. Thus, removal of the absorptive reservoir layer can occur without substantially disrupting the compressive force provided by the compression dressing. As used herein, “without substantially disrupting the compressive force” may include a change in compressive force of between 0% and 10%, more preferably between 0% and 5%. Accordingly, when the absorptive reservoir layer is removed, due to fluid saturation or other reasons that it may need replacing, the remaining layers of the compressive dressing will continue to provide at least 90% of the compressive force to the body part that it had provided prior to removal of the absorptive reservoir layer.
In one embodiment, the compression dressing of the present invention comprises at least one layer of moisture transport fabric comprised of elastic fiber, wherein the moisture transport fabric exhibits a sufficient amount of elasticity to apply a compressive force to a body part when applied thereto; wherein the moisture transport fabric is wrapped circumferentially and successively around a body part; wherein the compression dressing is at least 2 inches wide and 36 inches in length; and wherein the compression dressing provides one-way, active fluid management of fluid away from the body part and into the moisture transport fabric.
The moisture transport fabric of the compression dressing may be further characterized by having a first skin-facing surface which is primarily hydrophobic in nature and a second non skin-facing surface which is primarily hydrophilic in nature, wherein the hydrophobic and hydrophilic surfaces partially overlap each other when wrapped circumferentially and successively around a body part such that fluid transport occurs between sequential layers of hydrophilic and hydrophobic fabric.
In one embodiment, the skin-contacting layer may be attached to the moisture fabric transport layer. For example, the skin-contacting layer may be laminated to the moisture fabric transport layer prior to application to a body part. In this instance, the combined layers may then be wrapped circumferentially and successively around a body part.
The following examples further illustrate the present compression dressing but are not to be construed as limiting the invention as defined in the claims appended hereto. All parts and percents given in these examples are by weight unless otherwise indicated.
Example 1, an example of a moisture transport fabric layer as described herein, was a double jersey knit (circular knit), multi-polymer fabric sold by Milliken & Company. The fabric was single layer of fabric comprised of approximately 65% continuous filament polyamide yarn (nylon 6,6), 20% continuous filament polyester yarn, and 15% continuous filament spandex yarn. The polyamide yarn was comprised of 2 plies of 40 denier/34 filament count nylon 6 fiber that was exposed to a texturing process prior to knitting. The polyester yarn was comprised of single ply 70 denier/34 filament count fiber that was exposed to a texturing process prior to knitting. The spandex yarn was comprised of 55 denier/1 filament count fiber. The fabric was knitted in such as manner as to give a distinct nylon side and a distinct polyester side. The polyester side of the fabric was exposed to a face-finishing process known as sanding.
The fabric was passed through an aqueous bath containing an antimicrobial formulation comprised of 15% AlphaSan® RC 2000 (antimicrobial agent, 10% Ag) and 4% Witcobond® UCX-281F (polyurethane binder). The coated fabric was subsequently passed through squeeze rollers to achieve a wet pick-up of about 85%. The fabric was then dried in a tenter frame to remove excess liquid.
Example 1 was evaluated for surface energy characteristics and for tensile and elongation/compression properties, according to the test procedures described herein.
Example 1A was the same as Example 1, except that the spandex fiber of Example 1A was 140/1 yarn (rather than 55/1 yarn).
Example 2A was comprised of hydrophilic polyurethane foam, available from Rynel® of Wiscasset, Me.
Example 2B was comprised of 30W hydrophilic polyurethane foam, available from Filtrona of Richmond, Va.
Surface energy was determined by t/he Fowkes method using water and diiodomethane as probe liquids. The surface properties of these liquids are as follows:
Contact angles were determined by the sessile drop method. In order to obtain proper surface energy values on the surfaces, care was taken to measure initial spreading angles and not angles which were influenced (diminished) by the liquids soaking into the samples. To achieve this goal, high speed image analysis was utilized whereby images were taken of drops of liquids placed on the surface of each material at a rate of 360 times per second. Using small drops (e.g. 1.0 microliter), it was determined that the drops did in fact spread to characteristic angles, before soaking into the sample significantly, in the time frame of 0.1 seconds after droplet placement for these liquids. Thus, the contact angle was used that measured at 0.1 seconds for each probe liquid on each surface as the characteristic contact angle for surface energy determination. By 0.2 seconds and beyond, some drops (particularly of diiodomethane were not only spread, but were also significantly soaking into the samples).
The effective pressure of compression bandages was quantified by measuring the tension of bandages using a tensile test. Tension is used to quantify compression instead of pressure since the pressure exerted on a body part (e.g. a leg or other limb) is a function of body part radius (EQ1.2). Textile samples were prepared in 1″ to 4″ widths and 8″ lengths using a punch where needed. The samples were tested in either the machine direction or transverse direction of the textile.
Samples were mechanically tested for tensile strength, modulus, and recovery using a MTS Sintech 10/G mechanical tester with an MTS 25 kN load cell. The samples were held in 3″ wide hydraulic grips. Steel plates were used to hold samples wider than the 3″ hydraulic grips. No slippage was observed during testing. Thus, the samples experienced uniform stress across their width. A 5″ sample span between the grips was used. The MTS mechanical testing machine separated the hydraulic grips at a rate of 8 inches/minute, thereby stretching the samples. Samples were elongated multiple times and the force supported by the textile was measured in both extensional and relaxational directions.
Examples 1 and Examples 2A and 2B were tested for surface energy properties. The results are provided in Table 1A and 1B below.
Example 1 was tested using tensile testing after being stretched once. As seen in Tables 2A, 2B and 2C and in
Test results are provided in Tables 2A, 2B and 2C below.
The spandex content of the moisture transport fabric layer of the present invention was varied. Example 1, described in detail above, contained 55/1 ROICA® spandex/elastane fiber in the jersey knit portion of the construction. Example 1A was the same as Example 1, except that it contained more spandex content. In order to this increase in spandex content for Example 1A, a 140/1 ROICA® spandex/elastane fiber was used to replace every third feed of 55/1 ROICA® spandex/elastane fiber. Inserting this larger denier spandex in a portion of the jersey knit construction increased the total spandex content of the fabric by 51%. Alternate means of altering the elastic resistive force of the fabric under elongation include changing the number or size of spandex yarns in a portion of the jersey knit fabric, decreasing the portion of the jersey knit loops (feeds) which contain spandex fiber, changing the loop size and construction of the fabric, and/or using a different elastomeric material in the final fabric construction.
The increased spandex content fabric (Example 1A) was compared to the normal spandex fabric (Example 1) under 30% transverse heatset in the greige form.
Both fabrics were stretched to 100% elongation as described above. Test results are provided in Table 3 below.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the scope of the invention described in the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 61/306,629, entitled “Compression Dressing” which was filed on Feb. 22, 2010.
| Number | Date | Country | |
|---|---|---|---|
| 61306629 | Feb 2010 | US |
