Medical dressing with thermochromic indicator

Abstract

The invention discloses a medical dressing. The medical dressing comprises a backing layer, wherein the backing layer comprises a first main surface and a second main surface opposite to the first main surface; an adhesive on the second major surface of the backing layer; a release liner; and a thermochromic indicator having a color change sensitivity at a temperature in the range of about 20.0 DEG C to about 45 DEG C.

Description

Technical Field

[0001] The present disclosure relates to a medical dressing having a thermochromic indicator. Background Art

[0002] Intravenous (IV) infusion is a common clinical procedure in medical settings as a means of delivering biological fluids to patients. In the United States, approximately 80% of hospitalized patients receive IV therapy. Generally, a needle or cannula is inserted into a peripheral vein and connected to an IV bag containing the biological fluid via flexible connecting tubing. The biological fluid can be simply a saline solution and / or contain any of a variety of therapeutic agents and / or nutrients that can be administered via IV infusion.

[0003] Transparent film dressings are widely used as a protective layer on wounds because they promote healing in a moist environment while acting as a barrier to contaminating fluids and bacteria. The films are also used as surgical drapes due to their barrier properties. Dressings and drapes meeting the above description are available under various trade names, such as TEGADERM ™ (3M Company, St. Paul, Minn.) and OP-SITE ™ (Smith & Nephew, Hull, England). The polymer films used in these dressings and drapes are conformable, i.e., the films are very thin, flexible, and soft. They are typically provided with a releasable protective liner covering the adhesive-coated surface of the film.

[0004] The use of a removable carrier avoids the above problems by not requiring the film to be removed after placement on the patient. The carrier also aids in accurate placement of the dressing on the patient. There is a need for better medical dressings and non-clinical methods to detect infiltration. Summary of the Invention

[0005] Sometimes, and for a variety of reasons, a smart dressing is needed to detect temperature changes in the skin or subcutaneous tissue of a mammalian body. For example, IV fluid can infiltrate nonvascular tissue near the injection or infusion site, adversely affecting surrounding tissue and disrupting the treatment regimen. Furthermore, infiltration or extravasation can penetrate tissue distal to the IV infusion site, such as near the IV drainage system of an IV infusion. IV solutions can accumulate in the skin and subcutaneous tissue, potentially damaging the skin and tissue and preventing critical medications and / or nutrients from reaching the venous system.

[0006] Thus, in one aspect, the present disclosure provides a medical dressing comprising: a backing layer comprising a first major surface and a second major surface opposite the first major surface; an adhesive located on the second major surface of the backing layer; a release liner; and a thermochromic indicator having a color change sensitivity at a temperature in the range of about 20.0°C to about 45°C.

[0007] In another aspect, the present disclosure provides a method comprising providing a medical dressing of the present disclosure; applying the medical dressing to a mammalian body; and detecting a color change resulting from injection into the mammalian body.

[0008] Various aspects and advantages of the exemplary embodiments of the present disclosure have been summarized. The above summary of the invention is not intended to describe every illustrated embodiment or every specific implementation of the present disclosure. Additional features and advantages are disclosed in the following embodiments. The following figures and detailed description more specifically illustrate certain embodiments using the principles disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a side cross-sectional view of an exemplary embodiment of a medical dressing as described herein. DETAILED DESCRIPTION

[0010] Before explaining any embodiment of the present disclosure in detail, it should be understood that the present invention is not limited in its application to the details of the use, construction and arrangement of the components set forth in the following description. The present invention can have other embodiments and can be practiced or performed in various ways that will become apparent to those of ordinary skill in the art after reading this disclosure. In addition, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered restrictive. The use of "including," "comprising," or "having" and variations thereof herein is meant to cover the items listed thereafter and their equivalents and additional items. It should be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope of the present disclosure.

[0011] There is a need for smart dressings that detect temperature changes in the skin or subcutaneous tissue of a mammalian body. For example, various non-clinical methods have been proposed to detect infiltration. To date, these non-clinical methods have been largely unsuccessful. The flow resistance and / or increased pressure within the IV connection tubing is monitored by a detector that issues an alarm when the flow resistance or pressure increase exceeds a threshold. The medical dressing of the present disclosure (in which a thermochromic indicator is incorporated into the medical dressing) can provide a new device system that can be used to indicate temperature changes in the skin or subcutaneous tissue of a mammalian body to detect the occurrence of infiltration or extravasation during IV administration of a biological fluid to a mammalian body (such as a patient's body) or phlebitis, or to inform a user how to properly apply a medical dressing or detect edge ridges of a medical dressing indicator.

[0012] Figure 1 An exemplary embodiment of a medical dressing 100 as described herein is depicted. In one or more embodiments, the medical dressing 100 can be described as including a backing layer 120 having a first major surface 121 and a second major surface 122 opposite the first major surface 121. The medical dressing 100 also includes an adhesive 124 located on the second major surface of the backing layer 120, and a support material 130 secured to the second major surface 122 of the backing layer 120. In one or more embodiments, the medical dressing 100 can include an adhesive 134 located on a surface of the support material 130 facing away from the backing layer 120, so that both the backing layer 120 and the support material 130 can adhere to the patient's skin. In one or more embodiments, the medical dressing 100 can also include a release liner 112 releasably attached to the first major surface of the backing layer and the carrier 110. In one or more embodiments, the medical dressing 100 can also include a hydrogel island pad (not shown) adjacent to the second major surface of the backing. In some embodiments, the hydrogel island pads can be secured to the second major surface 122 of the backing layer 120 by an adhesive 124 located on the second major surface of the backing layer 120. In some embodiments, the hydrogel island pads can be secured to the second major surface 122 of the backing layer 120 by an adhesive 134 located on the surface of the support material 130 facing away from the backing layer 120. In one or more embodiments, the medical dressing 100 can also include a thermochromic indicator having color change sensitivity at a temperature in the range of about 20°C to about 45°C or about 25°C to about 35°C.

[0013] In one or more embodiments, the thermochromic indicator can be a dye, a colorant, an ink, or a pigment. In some embodiments, the dye can be a colored substance whose color can be detected by the human eye and / or by a colorimetric sensor. Examples of suitable thermochromic indicators can include any dye that changes color at temperatures between 20° C. and 45° C., such as blue-purple with a transition temperature of 22° C.; green-yellow, black-yellow, red-yellow, black-colorless, black-pink, black-blue, black-green, pink-colorless, yellow-colorless, black-purple with a transition temperature of 25° C.; black-colorless or red-colorless with a transition temperature of 28° C.; blue-purple, red-yellow, black-pink, black-yellow, red-colorless, blue-colorless, black-colorless with a transition temperature of 31° C.; red-colorless with a transition temperature of 29° C.; black-colorless, black-yellow, black-green, black-pink, black-purple with a transition temperature of 35° C.; black-colorless with a transition temperature of 38° C.; and red-colorless with a transition temperature of 45° C. In some embodiments, the thermochromic indicator can be a powder or dissolved or suspended in a solution. For example, leuco dyes are powdered pigments that can be mixed into a liquid material (water, uncured adhesive, clear paint, release coating solution, etc.) and then applied to a medical dressing.

[0014] The medical dressings described herein can be prepared using conventional techniques familiar to those skilled in the art (e.g., extrusion, solvent casting, calendaring, lamination, adhesive coating, etc.). U.S. Patent No. 6,685,682 (the disclosure of which is incorporated herein by reference) discloses some possible configurations and methods for preparing medical dressings having a backing layer and support material as described herein. In one or more embodiments, the thermochromic indicator can be incorporated into or located on any portion of the medical dressing, such as the backing layer, adhesive, release liner, support material, hydrogel island pad, or carrier of the medical dressing. In some embodiments, the thermochromic indicator can be transferred from the carrier to the backing layer upon removal of the carrier. In some embodiments, the thermochromic indicator can be printed on the medical dressing, such as on the backing layer, adhesive, release liner, support material, hydrogel island pad, or carrier of the medical dressing. In some embodiments, the thermochromic indicator may partially or completely cover or form a pattern on a backing layer, adhesive, release liner, support material, hydrogel island pad, or carrier of a medical dressing.

[0015] The thermochromic indicator can indicate a change in temperature from a temperature representative of normal skin to a temperature representative of IV fluid infiltration. Thus, the medical dressings of the present disclosure can detect temperature changes caused by cold fluid entering the tissue subcutaneously, for example, in the case of infiltration at an IV site. The transition temperature of the thermochromic indicator can be selected to be lower than the surface skin temperature, for example, in the range of about 20.0°C to about 35°C, so that when the fluid cools the tissue, the skin surface temperature drops below the transition temperature, thereby changing the color of the thermochromic indicator. In some embodiments, the medical dressing can be a primary or secondary medical dressing, such as those used for IV site dressings (e.g., IV catheter dressings), surgical dressings, general wound dressings, dressings that may or may not absorb fluids, dressings that may or may not contain gels or hydrogels, dressings used to prevent skin damage (such as abrasions), dressings that may or may not contain antimicrobial agents, dressings that may or may not contain hemostats, and dressings that are transparent or opaque.

[0016] The present disclosure also provides a method for detecting the occurrence of infiltration or extravasation. The method may include providing a medical dressing of the present disclosure, applying the medical dressing to a mammalian body, and detecting a color change resulting from an injection into the mammalian body. The method may also include inserting a hypodermic needle or cannula through the skin of the mammalian body, or into a blood vessel of the mammalian body covered by the medical dressing. The color change can be detected by the human eye and / or by a colorimetric detection device (e.g., a colorimetric sensor or an RGB-IR camera). The present disclosure provides a simple solution that requires no additional tools or equipment beyond the thermochromic indicator incorporated into the medical dressing. The medical dressing of the present disclosure can allow for non-invasive, constant passive temperature monitoring, which facilitates real-time identification of the location and magnitude of infiltration or extravasation using a visible color change. While existing techniques for detecting infiltration, such as electrical impedance and changes in light absorption, require separate devices, the medical dressing of the present disclosure can be used as a fixation dressing for catheter fixation and as a means of detecting IV-related complications, infiltration, and extravasation. The medical dressings of the present disclosure can also be used to detect phlebitis, thrombophlebitis, infection, patient temperature, changes in patient temperature, local injury, inflammation, changes in wound healing, dressing adhesion, bulging of the dressing edge, and air gaps in the dressing. In some embodiments, the medical dressings of the present disclosure can provide a thermal insulation effect for the thermochromic indicator within the dressing, so that the thermochromic indicator will be more affected by changes in skin / tissue temperature and less affected by ambient temperature or changes in ambient temperature.

[0017] Backing layer

[0018] The backing layer of one or more embodiments of the medical dressings described herein can provide an impermeable barrier to the passage of liquids and at least some gases. Representative backing layers can include nonwoven and woven webs, knitted fabrics, films, foams, polymer films, and other familiar backing materials. In some embodiments, a transparent backing layer is desired to allow observation of the skin or medical device below.

[0019] In one embodiment, the backing layer has a high water vapor permeability but is generally impermeable to liquid water, so that microorganisms and other contaminants are sealed out of the area below the backing layer. An example of a suitable material is a highly water vapor permeable membrane, such as described in U.S. Patent Nos. 3,645,835 and 4,595,001, the disclosures of which are incorporated herein by reference. In a highly water vapor permeable membrane / adhesive composite, the composite should absorb water at a rate equal to or greater than human skin, e.g., at least 200 g / m at 37°C / 100%-10% RH, using the inverted cup method as described in U.S. Patent No. 4,595,001. 2 / 24 hours rate, or at least 700g / m2 at 37℃ / 100%-10% RH 2 / 24 hours rate, or at least 2000g / m2 at 37℃ / 100%-10% RH 2 The backing layer can transmit water vapor at a rate of 1 / 24 hours. The adhesive of perforated substrate or film or pattern coating can be used to increase water vapor transmission rate. In one embodiment, the backing layer is an elastomeric polyurethane, polyester or polyether block amide film. These films combine the required properties of resilience, elasticity, high water vapor permeability and transparency. The description of this characteristic of the backing layer can be found in the US Patents No. 5,088,483 and No. 5,160,315 of the announcement, and the disclosures of these US Patents are incorporated by reference accordingly.

[0020] Commercially available examples of potentially suitable backing layers may include thin polymer film backings sold under the trade names TEGADERM (3M Company), OPSITE (Smith & Nephew Company), etc. Many other backing layers may also be used, including those commonly used to manufacture surgical incise drapes (e.g., incise drapes manufactured by 3M Company under the trade names STERIDRAPE and IOBAN), etc.

[0021] Because fluids can be actively removed from the sealed environment defined by the medical dressing, a relatively high water vapor permeable backing layer may not be required.Thus, some other potentially useful backing materials may include, for example, metallocene polyolefins, and SBS and SIS block copolymer materials may be used.

[0022] However, it may be desirable to keep the backing layer relatively thin, for example to improve conformability. For example, the backing layer may be formed from a polymer film having a thickness of 200 microns or less, or 100 microns or less, possibly 50 microns or less, or even 25 microns or less.

[0023] Support materials

[0024] The supporting material used in one or more embodiments of the medical dressing as described herein can provide strength for the backing layer. Therefore, the supporting material has greater rigidity and less elasticity than the backing layer. The supporting material can be a coating, such as an adhesive, or can be a self-supporting substrate, such as another film, woven fabric, knitted fabric or nonwoven fabric. For example, U.S. Patent No. 5,088,483 discloses a permanent adhesive as a reinforcing material, which can be used as a supporting material.

[0025] An example of a nonwoven material for the support material is a high-strength nonwoven fabric available from E.I. Dupont de Nemours & Company of Wilmington, Del. under the Sontara trademark, including Sontara 8010, a hydroentangled polyester fabric. Other suitable nonwoven webs include hydroentangled polyester fabrics available from Veratec, a division of International Paper of Walpole, Mass. Another suitable nonwoven web is the nonwoven elastomeric web described in U.S. Patent No. 5,230,701.

[0026] Adhesives

[0027] Suitable adhesives for use in one or more embodiments of medical dressings as herein described include any adhesive that provides acceptable adhesion to the skin and is acceptable for use on the skin (for example, adhesive should preferably be non-irritating and non-sensitizing). Suitable adhesives are pressure-sensitive and, in certain embodiments, have a relatively high water vapor transmission rate to allow water to evaporate. Suitable pressure-sensitive adhesives include those based on acrylates, polyurethanes, hydrogels, hydrophilic colloids, block copolymers, silicones, rubber-based adhesives (including natural rubber, polyisoprene, polyisobutylene, butyl rubber etc.) and the combination of these adhesives. Adhesive components can include tackifiers, plasticizers, rheology modifiers and active ingredients, including, for example, antimicrobial agents.

[0028] Pressure-sensitive adhesives useful in medical dressings may include adhesives typically applied to the skin, such as the acrylate copolymers described in U.S. Patent No. RE 24,906, particularly a 97:3 isooctyl acrylate:acrylamide copolymer. Another example may include a 70:15:15 isooctyl acrylate:ethylene oxide acrylate:acrylic acid terpolymer, as described in U.S. Patent No. 4,737,410 (Example 31). Other potentially useful adhesives are described in U.S. Patent Nos. 3,389,827; 4,112,213; 4,310,509; and 4,323,557. The inclusion of drugs or antimicrobial agents in adhesives is also contemplated, as described in U.S. Patent Nos. 4,310,509 and 4,323,557.

[0029] Silicone adhesives may also be used. Typically, silicone adhesives can provide suitable adhesion to the skin while being gently removed from the skin. Suitable silicone adhesives are disclosed in PCT publications WO 2010 / 056541 and WO 2010 / 056543.

[0030] In some embodiments, the pressure-sensitive adhesive can transmit water vapor at a rate greater than or equal to that of human skin. While this property can be achieved by selecting an appropriate adhesive, other methods of achieving high relative water vapor transmission rates are also contemplated, such as pattern coating the adhesive onto a backing, as described in U.S. Patent No. 4,595,001. Other potentially suitable pressure-sensitive adhesives may include blown microfiber (BMF) adhesives, such as those described, for example, in U.S. Patent No. 6,994,904. Pressure-sensitive adhesives used in wound dressings may also include one or more regions where the adhesive itself includes structures, such as, for example, the microreplicated structures described in U.S. Patent No. 6,893,655.

[0031] Issued U.S. Patents 3,645,835 and 4,595,001 describe methods for preparing such films and methods for testing their permeability. Preferably, the film / adhesive composite should transmit water vapor at a rate equal to or greater than that of human skin. Preferably, the adhesive-coated film should transmit water vapor at a rate of at least 200 g / m² using the inverted cup method as described in U.S. Patent 4,595,001. 2 / 24 hours / 37°C / 100%-10% RH, more preferably at least 700g / m 2 / 24 hours / 37°C / 100%-10% RH, and most preferably at least 2000g / m 2 / 24 hours / 37℃ / 100%-10% RH rate of water vapor transmission.

[0032] Different portions of the medical dressings described herein can include different adhesives, such as disclosed in US 2015 / 0141949, entitled "Medical Dressing with Multiple Adhesives." For example, one portion can include an acrylate adhesive, while another portion can include a silicone adhesive. In one embodiment, to prevent edge separation, the adhesive is present near the periphery, while the adhesive is present near the center. In one embodiment, to securely hold a device or tubing near the center, the adhesive is present near the periphery, while the adhesive is present near the skin-contacting periphery. In some embodiments, the medical dressings described can include multiple layers of adhesive. For example, one layer can be a continuously applied silicone adhesive, and another layer can be a pattern-applied acrylate adhesive.

[0033] hydrogel

[0034] Hydrogels can be cross-linked polymer gels. Hydrogels are typically very flexible. Hydrogels provide and maintain a moist environment at the point of contact on the skin by increasing the moisture content. Typically, hydrogels can be removed without causing trauma to the wound. Common ingredients include, for example, polyvinyl alcohol, sodium polyacrylate, acrylate polymers, and copolymers with hydrophilic groups. Commercially available examples of hydrogels are Flexigel hydrogel sheets available from Smith & Nephew and Tegaderm CHG dressings available from 3M in St. Paul, Minnesota.

[0035] Hydrocolloids are similar to hydrogels, but have the ability to absorb water. It should be understood that for the purposes of this disclosure, either hydrogels or hydrocolloids can be used. Hydrocolloids typically comprise a blend of a polymer matrix (such as a rubbery elastomer, e.g., polyisobutylene) combined with one or more water-soluble or water-swellable hydrocolloids (such as a dry powder mixture of pectin, gelatin, and carboxymethyl cellulose). Upon absorbing liquid, the hydrocolloid forms a gel-like substance. In some embodiments, the hydrogel can be UV-curable, wherein a photoinitiator is included in the formulation and the monomers are cured upon exposure to UV light.

[0036] Optional components

[0037] Absorbent materials can also be used in conjunction with the medical dressings described herein. The absorbent material can be the same as the wound dressing material (described below) or can be a separate component. The absorbent material can be made from any of a variety of materials, including but not limited to woven or non-woven cotton or rayon. The absorbent pad can be used to contain a variety of substances, optionally including antimicrobial agents, drugs for transdermal drug delivery, chemical indicators for monitoring hormones or other substances in the patient's body, and the like.

[0038] The absorbent may include a hydrocolloid composition, including those described in U.S. Pat. Nos. 5,622,711 and 5,633,010, the disclosures of which are hereby incorporated by reference. The hydrocolloid absorbent may include, for example, natural hydrocolloids such as pectin, gelatin, or carboxymethyl cellulose (CMC) (Aqualon Corp., Wilmington, Del.); semisynthetic hydrocolloids such as cross-linked carboxymethyl cellulose (CMC) (e.g., Ac-Di-Sol; FMC Corp., Philadelphia, Pa.); synthetic hydrocolloids such as cross-linked polyacrylic acid (PAA) (e.g., CARBOPOL; ™ No. 974P; BFGoodrich, Brecksville, Ohio), or a combination thereof. The absorbent material may also be selected from other synthetic and natural hydrophilic materials, including polymer gels and foams.

[0039] And may include an optional release liner, which covers all or part of the adhesive to prevent adhesive contamination. In one embodiment, the packaging containing the adhesive dressing can be used as a release liner. Suitable release liners can be made of a composite material of kraft paper, polyethylene, polypropylene, polyester or any of these materials. In one embodiment, the liner is coated with a release agent, such as a fluorochemical or silicone. For example, U.S. Patent No. 4,472,480 describes a perfluorochemical liner with low surface energy, the disclosure of which is hereby incorporated by reference. In one embodiment, the liner is a paper, polyolefin film or polyester film coated with a silicone release material.

[0040] An optional carrier may be included that covers all or a portion of the first major surface of the substrate to provide structural support if the dressing is thin and highly flexible. Once the adhesive dressing is placed on the skin, the carrier may be removed from the first major surface. The carrier may be constructed of a variety of materials, such as woven or knitted fabrics, nonwovens, papers, or films. In one embodiment, the carrier is disposed along the perimeter of the first major surface of the dressing and is removable from the first major surface, similar to the 3M Tegaderm® available from 3M Company in St. Paul, Minnesota. ™ Carrier used in transparent film dressings.

[0041] An optional antimicrobial agent may be included, either separate from the adhesive dressing or integral to the dressing. The antimicrobial component is placed near or adjacent to the insertion site of the medical device to inhibit the growth of microorganisms in and around the insertion site. The antimicrobial component may be an absorbent foam or gel, such as that available in 3M Tegaderm® from 3M Company. ™ The antimicrobial agent may be selected from the group consisting of parachlorometaxylenol, triclosan, chlorhexidine and its salts, polyhexamethylene biguanide and its salts, iodine, iodophors, silver oxide, silver and its salts, octenidine, olanexidine, peroxides, antibiotics, and combinations thereof.

[0042] The following embodiments are intended to illustrate the present disclosure rather than to limit the present disclosure.

[0043] Implementation Plan

[0044] Embodiment 1 is a medical dressing comprising: a backing layer comprising a first major surface and a second major surface opposite the first major surface; an adhesive located on the second major surface of the backing layer; a release liner; and a thermochromic indicator having color change sensitivity at a temperature in the range of about 20.0°C to about 45°C.

[0045] Embodiment 2 is the medical dressing of embodiment 1, wherein the thermochromic indicator is a dye, a colorant, an ink, or a pigment.

[0046] Embodiment 3 is the medical dressing of any one of embodiments 1 to 2, wherein the thermochromic indicator is a dye.

[0047] Embodiment 4 is the medical dressing of any one of embodiments 1 to 3, wherein the medical dressing is an IV site dressing.

[0048] Embodiment 5 is the medical dressing according to any one of embodiments 1 to 4, further comprising a support material fixed to the backing layer, wherein the elasticity of the support material is less than the elasticity of the backing layer.

[0049] Embodiment 6 is the medical dressing of any one of embodiments 1 to 5, further comprising an island pad of hydrogel adjacent the second major surface of the backing.

[0050] Embodiment 7 is the medical dressing of any one of embodiments 1 to 6, further comprising a carrier releasably attached to the first major surface of the backing layer.

[0051] Embodiment 8 is the medical dressing of any one of embodiments 1 to 7, further comprising an antimicrobial agent.

[0052] Embodiment 9 is a medical dressing according to embodiment 8, wherein the antimicrobial agent is selected from the group consisting of: parachlorometaxylenol; triclosan; chlorhexidine and its salts; polyhexamethylene biguanide and its salts; iodine; iodophors; silver oxide; silver and its salts; octenidine; olanexidine; peroxides; antibiotics; and combinations thereof.

[0053] Embodiment 10 is the medical dressing of any one of embodiments 1 to 9, wherein the thermochromic indicator is incorporated into or located on the backing layer, the adhesive, the release liner, the support material, the hydrogel island pad, or the carrier.

[0054] Embodiment 11 is the medical dressing of embodiment 10, wherein upon removal of the carrier, the thermochromic indicator is transferred from the carrier to the backing layer.

[0055] Embodiment 12 is the medical dressing of embodiment 10, wherein the thermochromic indicator is printed on the medical dressing.

[0056] Embodiment 13 is the medical dressing of any one of embodiments 1 to 12, wherein the thermochromic indicator indicates a change in temperature from a temperature indicative of normal skin to a temperature indicative of IV fluid infiltration.

[0057] Embodiment 14 is a method comprising providing the medical dressing of any one of embodiments 1 to 13; applying the medical dressing to a mammalian body; and detecting a color change resulting from injection into the mammalian body.

[0058] Embodiment 15 is a method according to embodiment 14, wherein the color change indicates IV fluid infiltration.

[0059] Embodiment 16 is a method according to any one of embodiments 14 to 15, further comprising inserting a hypodermic needle or cannula through the skin of the mammalian body, or into a blood vessel of the mammalian body covered by the medical dressing.

[0060] The following working examples are intended to illustrate the present disclosure but not to limit it.

[0061] Example

[0062] Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention.

[0063] Example 1

[0064] Thermochromic fabric coating solutions with a blue to colorless color transition at 31°C, a black to colorless color transition at 28°C, and a green to yellow color transition at 25°C are available from Atlanta Chemical Engineering LLC, Tampa, FL. Each solution was coated with a No. 28 Meyer rod onto the polyurethane film side of a 10-inch wide adhesive laminate (3M Company, St. Paul, Minnesota) consisting of polyurethane film, adhesive, and release liner and allowed to dry overnight. Each dye-coated sample was then cut into a 2-inch x 2-inch dressing sample. Two dressing samples of each applied dye-coated sample were prepared for a total of six dressing samples.

[0065] Freshly euthanized, untreated young adult female mixed breed farm pigs (Yorkshire X from Midwest Research Swine, Gibbon, MN) with minimal skin pigmentation and weighing 10-40 kg were used. To minimize complications, hair and dirt were removed from the pig skin at the intended application site prior to the study. A thermal blanket (3M, St. Paul, MN) was used to maintain pig body temperature throughout the study. Prior to euthanasia, pairs of each applied dressing were applied to the pig's abdomen.

[0066] After euthanasia of the pigs, room temperature 0.9% sodium chloride injection solution (Patterson Veterinary Services, Loveland, CO) was injected intravenously and subcutaneously into the vein beneath each dressing pair through an 18-gauge or 20-gauge needle (Becton-Dickinson, Franklin Lakes, NJ). The saline solution was injected in 2 mL increments every 10 seconds until 12 mL was reached. The dressing began to change from blue to colorless after 2-4 mL of subcutaneous injection. The dressing also changed from black to colorless after 2-4 mL of saline injection. Each dressing was initially colorless after application, and the cooler saline temperature induced localized changes from colorless to blue and black, respectively. Subcutaneous injection produced a diffuse, elliptical color change. Intravenous injection produced a narrow, linear color band. The remaining dressings, coated with a dye that changes from green to yellow at 25°C, remained unchanged during the experiment. Temperature data were collected with an IR camera (Teledyne FLIR, Wilsonville, OR), and the observed color changes were shown to correlate with changes in surface temperature.

[0067] Example 2

[0068] Thermochromic fabric coating solution (blue to colorless at 31°C, Atlanta Chemical Engineering, LLC, Tampa, Florida) was applied to the polyurethane film side of an 8-inch-wide adhesive laminate consisting of polyurethane film, adhesive, and release liner (3M Company, St. Paul, Minnesota) using a Meyer rod (No. 8) and then dried in a 150°F oven for two minutes. The dye-coated sample was then cut into 5.5-inch by 5.5-inch squares to provide experimental dressing samples.

[0069] Freshly euthanized, untreated, young adult female, mixed breed farm pigs (Yorkshire X, Midwest Laboratory Swine Producers, Gibbon, Minnesota), with minimal skin pigmentation and weighing 10-40 kg, were used for this study. To minimize complications, hair and dirt were removed from the pig skin at the intended application site prior to the study. A warming blanket (3M, St. Paul, Minnesota) was used to maintain pig body temperature throughout the study. A 20-gauge x 1¼” INTROCAN safety catheter (B. Braun, Bethlehem, PA) was inserted subcutaneously into the right abdominal region of the pig for injection, and the dye-coated dressing sample was applied to cover the catheter. The dressing turned colorless upon application to the skin surface. Sodium chloride injection solution (0.9%) (Patterson Veterinary Services, Loveland, CO) was infused subcutaneously into the pig using an infusion pump (Baxter, Deerfield, IL) at a flow rate of 100 ml / hour to simulate infiltration. When approximately 2 ml–3 ml of saline was infused near the catheter tip, the dressing began to turn blue, forming a diffuse oval shape originating from the catheter tip.

[0070] Example 3

[0071] Polyvinylpyrrolidone K90, supplied by Ashland Chemical (Wilmington, Del.), with a molecular weight of approximately 1,570,000 g / mol, was added to purified water to prepare a 2 wt% aqueous solution. A thermochromic black-leuco dye powder (Atlanta Chemical Engineering, LLC, Tampa, Florida) with a thermal transition at 28°C was added to a previously prepared 2 wt% aqueous solution of polyvinylpyrrolidine to a dye concentration ranging from 0.6 wt% to 3 wt%. A white SONTARA nonwoven (supplied by Glatfelter Paper, Charlotte, NC) was soaked in the dye-polyvinylpyrrolidine solution for 5 minutes, then removed and air-dried. This dye-containing SONTARA was then combined with an adhesive laminate (3M Company, St. Paul, Minnesota) consisting of a polyurethane film and an acrylate adhesive to form an experimental dressing prototype.

[0072] Freshly euthanized, untreated young adult female mixed-breed farm pigs (Yorkshire X from the Midwest Laboratory Swine Producers Center in Gibbon, Minnesota) with minimal skin pigmentation and weighing 10-40 kg were used in this study. To minimize complications, hair and dirt were removed from the pigs' skin at the intended application site prior to the study. A warming blanket (3M, St. Paul, Minnesota) was used to maintain body temperature throughout the study. A 20-gauge x 1 1 / 4-inch Introcan safety catheter (B. Braun, Bethlehem, Pennsylvania) was inserted subcutaneously into the right abdominal region of the pigs for injection, and then the experimental dressing sample was applied to cover the insertion site. During application, the dressing turned SONTARA white, and 0.9% sodium chloride injection solution (Patterson Veterinary Services, Loveland, Colorado) was infused subcutaneously into the pigs at a flow rate of 100 ml / hour to simulate infiltration. The dressing began to turn gray-black when approximately 3-4 ml of saline was infused near the catheter tip.

[0073] Example 4

[0074] Thermochromic dye powder (Atlanta Chemical Engineering, LLC, Tampa, Florida) was added to a 1:1 ratio of ethyl acetate and heptane (3M, St. Paul, Minnesota) containing an acrylic pressure-sensitive adhesive at the concentrations shown in Table 1, mixed, and then coated onto a primed 1-mil PET film (3M, St. Paul, Minnesota). The coated film was then dried at 70°C for 10 minutes to obtain a dry, dye-containing pressure-sensitive adhesive having a thickness of approximately 1 mil. The adhesive was then laminated to a PELLETHANE 5863-86A-VG film backing (Lubrizol, Wickliffe, Ohio) to provide an adhesive-film construction with a thermochromic dye in the adhesive.

[0075] Test specimens measuring 2.54 cm x 12.7 cm were cut from each adhesive film construction. The PET liner was removed from the adhesive and each test specimen was laminated to a test panel by placing the adhesive side of each specimen on the panel and laminating using two 5-pound rollers in each direction. The test panels were #320 stainless steel. Peel tests were conducted using a Zwick tensile tester (Z005) equipped with a 50 kg load cell at room temperature with a separation rate of 30.5 cm / min. Each test was performed in triplicate. The reported results are the average of the three measurements reported in ounces / inch and are summarized in Table 1.

[0076] Example 5

[0077] Thermochromic dye powder (Atlanta Chemical Engineering, LLC, Tampa, Florida) was added to water along with polyglycerol, hydroxypropyl guar gum (Solvay, Princeton, NJ), and gamma-irradiated polyvinylpyrrolidone K90 (Ashland Chemical, Wilmington, Delaware). The mixture was then hot-pressed into 30-mil-thick gel sheets containing 0.85% dye by weight. The gels exhibited a temperature-dependent color change from dark blue to light blue or from black to light gray.

[0078] Example 6

[0079] A thermochromic coating solution containing a thermochromic dye (Atlanta Chemical Engineering, LLC, Tampa, Florida) with a black-to-colorless transition at 28°C was coated onto the polyurethane film side (ESTANE 58237 TPU, Lubrizol, Wycliffe, Ohio) of an eight-inch-wide adhesive laminate (3M Company, St. Paul, Minnesota) consisting of a polyurethane film, adhesive, and release liner using a No. 20 Meyer rod and then dried in a 150°F oven for two minutes. The black-dyed adhesive laminate was then coated with a second thermochromic coating solution using a No. 20 Meyer rod and dried in a 150°F oven for two minutes. The dye in the second thermochromic coating solution has a blue-to-colorless transition at 31°C. The two-dye-coated sample was cut into 1-inch by 1-inch pieces and used to generate a color change versus temperature curve.

[0080] A 1-inch x 1-inch sample was placed on a hot plate and the temperature was increased from 25°C to 40°C. Two videos were captured simultaneously: one recorded with a digital camera to capture the color changes, and one recorded with a thermal camera to capture the temperature changes. For each video, a box selection was made of the background (corner of the plate) and the middle of each sample square in the sample block. The color values ​​within this selection were then averaged. Each video pair was synchronized.

[0081] To obtain a measure of perceived color variation, the Euclidean distance between the dressing color and the background was calculated in the CIELAB color space. The CIELAB color space was designed to be perceptibly uniform to the human eye, with various modifications and weightings added over the years to handle various color applications and new corrections. Distance in this color space is a useful quantitative measure for determining the amount of color variation in a dressing, how different the dressing color is from a constant background, and informing how easily an observer can detect a change in dressing color.

[0082] Color change was calculated using the following method. Visible and thermal images of warm and cool dressings were recorded. A region of interest was selected in the video frame that included a portion of the sample dressing and a white background. The frames captured from the visible camera were converted to CIELAB color space using the OpenCV Python package, and each region of interest was averaged. Once in CIELAB color space, the Euclidean distance between the background color and the sample dressing color was calculated and correlated with the associated temperature obtained from the IR camera video frame. The Euclidean distance between the dressing color and the background color was plotted on the y-axis, and the associated temperature was plotted on the x-axis. Using this information, we can quantify the perceived color change of the dressing as the temperature changes, and compare between dressings with different transition temperatures and different color schemes.

[0083] The experimental dressing had two transition temperatures, one near 29°C and the other near 33°C.

[0084] Example 7: UV curing gel

[0085] A mixture of 8.1 g of 480 average molecular weight poly(ethylene glycol) methyl ether acrylate (Sigma-Aldrich, St. Louis, MO), 5.9 g of 4-hydroxybutyl acrylate (BASF, Palmyra, MO), 4.0 g of a mixed lauryl acrylate blend, 0.027 g of Irgacure 2959 photoinitiator, 0.009 g of Irgacure 819 photoinitiator, and 0.18 g of a thermochromic pigment that turns from black to a colorless powder at 28° C. (Atlanta Chemical Engineering, LLC, Tampa, FL) was mixed on a shaker for at least 24 hours. The mixed lauryl acrylate blend was prepared according to Example 9 of U.S. Patent No. 9,102,774 (Clapper et al.). The mixture was then coated between two silicone-coated polyester release liners and cured to provide a cured adhesive film with a thickness of approximately 0.25 mm. Curing was performed using ultraviolet (UV) irradiation for approximately 30 minutes under a closed set of six 350 Blacklight F15TB / 350BL 15W bulbs (SYLVANIA brand). The cured sample was mostly opaque and black at room temperature. When heated in an oven at 60°C for 10 minutes, the sample became translucent white. The translucent sample had sufficient transparency to allow printed text to be visible through the gel.

[0086] Example 8 :

[0087] A mixture of 8.1 g of 480-average molecular weight poly(ethylene glycol) methyl ether acrylate (Sigma-Aldrich, St. Louis, MO), 5.9 g of 4-hydroxybutyl acrylate (BASF, Palmyra, MO), 4.0 g of a mixed lauryl acrylate blend, 0.027 g of Irgacure 2959 photoinitiator, and 0.009 g of Irgacure 819 photoinitiator was mixed on a shaker for at least 24 hours before coating between two silicone-coated polyester release liners and curing using ultraviolet (UV) irradiation for approximately 30 minutes under a closed set of six 350 Blacklight F15TB / 350BL 15W bulbs (SYLVANIA brand).

[0088] Two layers of gel were prepared following the above procedure, one with a thickness of 0.075 mm and the other with a thickness of 0.25 mm. The thick gel layer was then pattern coated with a thermochromic coating solution (black to colorless at 28°C, Atlanta Chemical Engineering, LLC, Tampa, Florida) by screen printing. The screen was a 50-micron thick polyester release liner with 20% openings and multiple 2.2-mm diameter holes. After coating, the samples were dried in an oven at 60°C for 60 minutes. The thin layer of gel was then laminated to the screen-printed side of the thick gel sample to produce a multilayer gel with a dry pigment layer between the two layers of gel. ESTANE 58237 was then applied to the screen at a thickness of 0.9 mils. ® A polyurethane film of TPU (Lubrizol, Wycliffe, Ohio) was laminated to the back of the thicker gel layer. At room temperature, the sample was transparent with black dots. When heated in an oven at 60°C for 10 minutes, the dried paint dots turned translucent white.

[0089] All references and publications cited herein are expressly incorporated herein by reference in their entirety. Exemplary embodiments of the present invention have been discussed, and reference has been made to possible variations within the scope of the present invention. For example, features described in conjunction with an exemplary embodiment may be used in conjunction with other embodiments of the present invention. These and other variations and modifications in the present invention will be apparent to those skilled in the art without departing from the scope of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments set forth herein. Therefore, the present invention is limited only by the claims provided below and their equivalents.

Claims

1. A medical dressing, comprising: a backing layer comprising a first major surface and a second major surface opposite the first major surface; an adhesive disposed on the second major surface of the backing layer; release liner; and A thermochromic indicator having color change sensitivity at a temperature in the range of about 20.0°C to about 45°C.

2. The medical dressing according to claim 1, wherein the thermochromic indicator is a dye, a colorant, an ink or a pigment.

3. The medical dressing according to any one of claims 1 to 2, wherein the thermochromic indicator is a dye.

4. The medical dressing according to any one of claims 1 to 3, wherein the medical dressing is an IV site dressing. 5 . The medical dressing according to claim 1 , further comprising a support material fixed to the backing layer, wherein the elasticity of the support material is less than that of the backing layer.

6. The medical dressing of any one of claims 1 to 5, further comprising an island pad of hydrogel adjacent the second major surface of the backing.

7. The medical dressing of any one of claims 1 to 6, further comprising a carrier releasably attached to the first major surface of the backing layer.

8. The medical dressing according to any one of claims 1 to 7, further comprising an antimicrobial agent.

9. The medical dressing of claim 8, wherein the antimicrobial agent is selected from the group consisting of: parachlorometaxylenol; triclosan; chlorhexidine and its salts; polyhexamethylene biguanide and its salts; iodine; iodophors; silver oxide; silver and its salts; octenidine; olanexidine; peroxides; antibiotics; and combinations thereof.

10. The medical dressing of any one of claims 1 to 9, wherein the thermochromic indicator is incorporated into or located on the backing layer, the adhesive, the release liner, the support material, the hydrogel island pad, or the carrier.

11. The medical dressing of claim 10, wherein upon removal of the carrier, the thermochromic indicator is transferred from the carrier to the backing layer.

12. The medical dressing of claim 10, wherein the thermochromic indicator is printed on the medical dressing.

13. The medical dressing of any one of claims 1 to 12, wherein the thermochromic indicator indicates a change in temperature from a temperature indicative of normal skin to a temperature indicative of IV fluid infiltration.

14. A method comprising: Providing a medical dressing according to any one of claims 1 to 13; applying the medical dressing to a mammalian body; A color change resulting from the injection into the body of said mammal is detected.

15. The method of claim 14, wherein the color change indicates IV fluid infiltration.

16. The method of any one of claims 14 to 15, further comprising inserting a hypodermic needle or cannula through the skin of the mammalian body, or into a blood vessel of the mammalian body covered by the medical dressing.

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