Medical dressing having a thermochromic indicator

Abstract

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

Description

[Technical Field]

[0001] The present disclosure relates to medical dressings having thermochromic indicators. [Background technology]

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

[0003] Transparent film dressings are widely used as a protective layer over wounds because they promote healing in a moist environment while acting as a barrier against contaminating fluids and bacteria. Films are also used as surgical drapes due to their barrier properties. Dressings and drapes that fit the above description are available under several 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 extremely thin, flexible, and pliable. They are typically supplied with a removable protective liner that covers the adhesive-coated surface of the film.

[0004] The use of a removable carrier that does not require tearing of the film after placement on the patient avoids the above-mentioned problems. The carrier also aids in accurate placement of the dressing on the patient. There is a need for better medical dressings and non-clinical approaches to detecting infiltration. Summary of the Invention

[0005] A variety of causes sometimes require a smart dressing to detect temperature changes in the skin or subcutaneous tissue of a mammalian body. For example, IV fluids can infiltrate non-vascular tissues adjacent to the injection or infusion site, adversely affecting surrounding tissues and disrupting treatment schedules. Furthermore, infiltration or extravasation can penetrate tissues distal to the IV infusion site, such as near the venous drainage system of an IV infusion. IV solutions can accumulate in the skin and subcutaneous tissues, potentially damaging the skin and tissues and preventing important drugs and / or nutrients from reaching the venous system.

[0006] Accordingly, in one aspect, the present disclosure provides a medical dressing comprising a backing layer having a first major surface and a second major surface opposite the first major surface, an adhesive on the second major surface of the backing layer, a release liner, and a thermochromic indicator having color change sensitivity at temperatures ranging from 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 an injection into the mammalian body.

[0008] Various aspects and advantages of exemplary embodiments of the present disclosure have been summarized. The above summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure. Additional features and advantages are disclosed in the following embodiments. The following drawings and detailed description more particularly exemplify specific embodiments that utilize the principles disclosed herein. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side cross-sectional view of one exemplary embodiment of a medical dressing described herein. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing any embodiment of the present disclosure in detail, it is to be understood that the invention is not limited in its application to the details of use, structure, and arrangement of components set forth in the following description. The invention is capable of other embodiments and of being practiced or carried out in various ways that will become apparent to those skilled in the art upon reading this disclosure. It is also to be understood that the phraseology and terminology used herein are for purposes of description and should not be regarded as limiting. The use of "including," "comprising," or "having," and variations thereof, herein is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

[0011] A smart dressing is needed to detect temperature changes in the skin or subcutaneous tissue of a mammalian body. For example, various non-clinical approaches have been proposed for detecting infiltration. To date, these non-clinical methods have been largely unsuccessful. Increases in resistance to flow and / or pressure in IV connector tubing are monitored by a detector that issues an alarm when the flow resistance or pressure increases beyond 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 useful for indicating temperature changes in the skin or subcutaneous tissue of a mammalian body to detect infiltration or extravasation, or the occurrence of phlebitis, during IV administration of biological fluids to a mammalian body, such as a patient's body, to instruct the user on how to properly apply the medical dressing, or to detect lifting of the edges of the medical dressing.

[0012] FIG. 1 shows one exemplary embodiment of a medical dressing 100 described herein. In one or more embodiments, the medical dressing 100 may 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 backing material 130 secured to the second major surface 122 of the backing layer 120. In one or more embodiments, the medical dressing 100 may include an adhesive 134 on a surface of the backing material 130 facing away from the backing layer 120 such that both the backing layer 120 and the backing material 130 may be adhered to a patient's skin. In one or more embodiments, the medical dressing 100 may also include a release liner 112 and a carrier 110 releasably attached to the first major surface of the backing layer. In one or more embodiments, the medical dressing 100 may also include a hydrogel island pad (not shown) proximate the second major surface of the backing. In some embodiments, the hydrogel island pad may 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 pad may be secured to the second major surface 122 of the backing layer 120 by an adhesive 134 on the surface of the backing material 130 facing away from the backing layer 120. In one or more embodiments, the medical dressing 100 may also include a thermochromic indicator having a color change sensitivity at temperatures ranging from about 20°C to about 45°C, or from about 25°C to about 35°C.

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

[0014] The medical dressings described herein can be made by conventional techniques familiar to those skilled in the art (e.g., extrusion, solvent casting, calendaring, lamination, adhesive coating, etc.). U.S. Pat. No. 6,685,682 (the disclosure of which is incorporated herein by reference) discloses several potentially useful structures and methods for making medical dressings having a backing layer and a 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 migrate 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 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 the backing layer, adhesive, release liner, support material, hydrogel island pad, or carrier of the medical dressing.

[0015] The thermochromic indicator can indicate a change in temperature from a temperature indicative of normal skin to a temperature indicative of IV fluid infiltration. Thus, the medical dressing of the present disclosure can pick up temperature changes induced 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 below the skin surface temperature, for example, within a range of about 20.0°C to about 35°C, so that as the fluid cools the tissue, the skin surface temperature drops below the transition temperature, causing the thermochromic indicator to change color. In some embodiments, the medical dressing may be one used for primary or secondary medical dressings, such as 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 injuries such as abrasions, dressings that may or may not contain antimicrobial agents, dressings that may or may not contain hemostatic agents, clear or opaque dressings.

[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 injection into the mammalian body. The method may also include inserting a hypodermic needle or cannula through the skin of the mammalian body covered by the medical dressing or into a blood vessel of the mammalian body. The color change can be detected by the human eye and / or by a colorimetric detection device, such as a colorimetric sensor or an RGB-IR camera. The present disclosure provides a convenient solution that does not require additional tools or devices other than a thermochromic indicator incorporated into the medical dressing. The medical dressing of the present disclosure may enable noninvasive and constant passive temperature monitoring, which helps identify the location and size of infiltration or extravasation in real time using visible color changes. While existing technologies for detecting infiltration, such as electrical impedance and light absorption changes, require separate devices, the medical dressings of the present disclosure can function as a securement dressing to provide catheter fixation and as a means for 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, patient temperature changes, local injury, inflammation, changes in wound healing, dressing adhesion, dressing edge lifting, and dressing voids. In some embodiments, the medical dressings of the present disclosure can provide an insulating effect for the thermochromic indicator within the dressing, so that the thermochromic indicator is more affected by changes in skin / tissue temperature and less affected by changes in ambient or ambient temperature.

[0017] Backing layer 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. Exemplary backing layers can include nonwoven and woven fibrous webs, knits, films, foams, polymeric films, and other well-known backing materials. In some embodiments, a transparent backing layer is desirable to allow visualization of the underlying skin or medical device.

[0018] In one embodiment, the backing layer has high water vapor permeability but is generally impermeable to liquid water, so that microorganisms and other contaminants are sealed off from the area below the backing layer. One example of a suitable material is a highly water vapor permeable film such as those 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 film / adhesive composite, the composite should have a water vapor permeability of at least 200 g / m2 at 37°C / 100-10% RH, for example, using the inverted cup method as described in U.S. Patent No. 4,595,001. 2 / 24 hours or at least 700g / m at 37℃ / 100-10%RH 2 / 24 hours or at least 2000g / m at 37℃ / 100-10%RH 2 The backing layer should transmit water vapor at a rate equal to or greater than that of human skin, such as a 1 / 24 hour rate. Perforated substrates or films or pattern-coated adhesives can be used to increase water vapor permeability. In one embodiment, the backing layer is an elastomeric polyurethane, polyester, or polyether block amide film. These films combine desirable properties, including resilience, elasticity, high water vapor permeability, and transparency. A description of this feature of the backing layer can be found in issued U.S. Patent Nos. 5,088,483 and 5,160,315, the disclosures of which are incorporated herein by reference.

[0019] Commercially available examples of potentially suitable backing layers may include thin polymeric film backings sold under the trade names TEGADERM (3M Company), OPSITE (Smith & Nephew), etc. Many other backing layers may also be used, including those commonly used in the manufacture of surgical incise drapes (e.g., incise drapes manufactured by 3M Company under the trade names STERIDRAPE and IOBAN).

[0020] Because fluids can be actively removed from the sealed environment defined by the medical dressing, a relatively highly moisture vapor permeable backing layer may not be required. As a result, several other potentially useful backing materials may include, for example, metallocene polyolefins, and SBS and SIS block copolymer materials can be used.

[0021] However, it may nevertheless be desirable to keep the backing layer relatively thin, for example to improve conformability, For example, the backing layer may be formed of a polymer film having a thickness of 200 micrometers or less, or 100 micrometers or less, potentially 50 micrometers or less, or even 25 micrometers or less.

[0022] supporting material The support material used in one or more embodiments of the medical dressing described herein can provide strength to the backing layer. Thus, the support material is more rigid and less elastic than the backing layer. The support material can be a coating such as an adhesive, or 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 that can be used as the support material.

[0023] An example of a nonwoven fabric for the support material is a high-strength nonwoven available under the Sontara trademark from EI Dupont de Nemours & Company of Wilmington, Delaware, 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, Massachusetts. Another suitable nonwoven web is the nonwoven elastomeric web described in U.S. Pat. No. 5,230,701.

[0024] adhesive Suitable adhesives for use in one or more embodiments of the medical dressings described herein include any adhesive that provides acceptable adhesion to the skin and is acceptable for use on the skin (e.g., the adhesive should preferably be non-irritating and non-sensitizing). Suitable adhesives are pressure-sensitive and, in certain embodiments, may have a relatively high water vapor transmission rate to allow for moisture evaporation. Suitable pressure-sensitive adhesives include those based on acrylates, urethanes, hydrogels, hydrocolloids, block copolymers, silicones, rubber-based adhesives (including natural rubber, polyisoprene, polyisobutylene, butyl rubber, etc.), and combinations of these adhesives. The adhesive components may contain tackifiers, plasticizers, rheology modifiers, and active ingredients, including, for example, antimicrobial agents.

[0025] Pressure-sensitive adhesives that can be used in medical dressings include adhesives typically applied to the skin, such as the acrylate copolymers described in U.S. Reissue Patent No. 24,906, particularly the copolymer of isooctyl acrylate and acrylamide 97:3. Another example is the isooctyl acrylate:ethylene oxide acrylate:acrylic acid terpolymer 70:15:15 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. It is also contemplated to include medicinal or antibacterial agents in the adhesive, as described in U.S. Patent Nos. 4,310,509 and 4,323,557.

[0026] Silicone adhesives can also be used. Generally, 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.

[0027] In some embodiments, pressure-sensitive adhesives can transmit water vapor at a rate equal to or greater than that of human skin. While this property can be achieved by selecting an appropriate adhesive, it is also contemplated that other methods for achieving a high relative water vapor transmission rate may be used, such as pattern-coating an adhesive onto a backing, as described in U.S. Patent No. 4,595,001. Other potentially suitable pressure-sensitive adhesives include blown-microfiber (BMF) adhesives, such as those described in U.S. Patent No. 6,994,904. Pressure-sensitive adhesives used in wound dressings may also include one or more regions in which the adhesive itself contains a structure, such as the microreplicated structure described in U.S. Patent No. 6,893,655.

[0028] Issued U.S. Patent Nos. 3,645,835 and 4,595,001 describe methods for making such films and 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 has a permeability of at least 200 g / m using the inverted cup method as described in U.S. Patent No. 4,595,001. 2 / 24 hours / 37℃ / 100-10%RH, preferably at least 700g / m 2 / 24 hours / 37℃ / 100-10%RH, most preferably at least 2000g / m 2 / 24 hours / 37℃ / 100-10%RH permeates water vapor at a rate of

[0029] Different portions of the medical dressings described herein may contain different adhesives, such as those disclosed in U.S. Patent Application Publication No. 2015 / 0141949, entitled "Medical Dressing with Multiple Adhesives." For example, one portion may contain an acrylate adhesive and another portion may contain a silicone adhesive. In one embodiment, there is an acrylate adhesive adjacent to the periphery and a silicone adhesive near the center to prevent edge separation. In one embodiment, there is an acrylate adhesive near the center to provide strong fixation with a device or tube, and a silicone adhesive near the periphery that contacts the skin. In some embodiments, the described medical dressings may contain multiple layers of adhesives. For example, one layer may be a continuous-coated silicone adhesive and another layer may be a pattern-coated acrylate adhesive.

[0030] hydrogel Hydrogels can be crosslinked polymer gels. Hydrogels are typically very flexible. By increasing their water content, hydrogels provide and maintain a moist environment at the point of contact on the skin. Generally, hydrogels can be removed without trauma to the wound. Common components include polyvinyl alcohol, sodium polyacrylate, acrylate polymers, and copolymers with hydrophilic groups. Commercially available examples of hydrogels include Flexigel Hydrogel Sheet, available from Smith & Nephew, and Tegaderm CHG dressing, available from 3M Company (St. Paul, Minn.).

[0031] Hydrocolloids are similar to hydrogels, but have the ability to absorb water. For purposes of this disclosure, it is understood that either hydrogels or hydrocolloids may be used. Hydrocolloids typically comprise a blend of a polymer matrix, such as a rubbery elastomer like polyisobutylene, combined with one or more water-soluble or water-swellable hydrocolloids, such as a dry powder mixture of pectin, gelatin, and carboxymethylcellulose. Upon absorbing liquid, the hydrocolloid forms a gel-like substance. In some embodiments, the hydrogel may be UV-curable, where a photoinitiator is included in the formulation and the monomer is cured upon exposure to UV light.

[0032] Optional ingredients Absorbent materials can also be used with the medical dressings described herein. The absorbent material can be the same as the wound packing material (described below) or can be a separate element. The absorbent material can be made of any of a variety of materials, including, but not limited to, woven or nonwoven cotton or rayon. Absorbent pads are useful for containing multiple substances, optionally including antimicrobial agents, drugs for transdermal drug delivery, chemical indicators for monitoring hormones or other substances in a patient, and the like.

[0033] The absorbent may comprise a hydrocolloid composition, including those described in U.S. Patent Nos. 5,622,711 and 5,633,010, the disclosures of which are incorporated herein by reference. Hydrocolloid absorbents can include, for example, natural hydrocolloids such as pectin, gelatin, or carboxymethylcellulose (CMC) (Aqualon Corp., Wilmington, Del.), semi-synthetic hydrocolloids such as cross-linked carboxymethylcellulose (X4ink 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 combinations thereof. Absorbent materials can also be selected from other synthetic and natural hydrophilic materials, including polymer gels and foams.

[0034] An optional release liner may be included to cover all or part of the adhesive to prevent contamination of the adhesive. In one embodiment, the package containing the adhesive dressing can function as the release liner. Suitable release liners can be made from kraft paper, polyethylene, polypropylene, polyester, or a composite of 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, the disclosure of which is incorporated herein by reference, describes a low surface energy perfluorochemical liner. In one embodiment, the liner is paper, a polyolefin film, or a polyester film coated with a silicone release material.

[0035] An optional carrier may be included that covers all or part of the first major surface of the substrate and provides structural support when the dressing is thin and highly flexible. The carrier may be removable from the first major surface once the adhesive dressing is placed on the skin. The carrier may be composed of a variety of materials, such as woven or knitted fabrics, nonwoven materials, paper, or films. In one embodiment, the carrier follows the periphery of the first major surface of the dressing and is removable from the first major surface, similar to the carrier used in 3M Tegaderm™ transparent film dressings available from 3M Company (St. Paul, Minnesota).

[0036] The optional antimicrobial agent may be included separately from the adhesive dressing or may be integral to the dressing. The antimicrobial component is placed near or adjacent to the insertion site of the medical device to inhibit microbial growth in and around the insertion site. The antimicrobial component may be an absorbent foam or gel, such as that used in 3M Tegaderm™ CHG IV Fixative Dressing, available 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, peroxide, antibiotics, and combinations of the foregoing.

[0037] The following embodiments are intended to illustrate, but not limit, the present disclosure.

[0038] Embodiment Embodiment 1 is a medical dressing material comprising a backing layer having a first major surface and a second major surface opposite the first major surface, an adhesive on the second major surface of the backing layer, a release liner, and a thermochromic indicator having color change sensitivity at temperatures ranging from about 20.0°C to about 45°C.

[0039] Embodiment 2 is the medical dressing of embodiment 1, wherein the thermochromic indicator is a dye, colorant, ink, or pigment.

[0040] Embodiment 3 is the medical dressing of embodiment 1 or 2, wherein the thermochromic indicator is a dye.

[0041] Embodiment 4 is a medical dressing material according to any one of embodiments 1 to 3, which is an IV site dressing material.

[0042] Embodiment 5 is a medical dressing according to any one of embodiments 1 to 4, further comprising a support material secured to the backing layer, the support material being less elastic than the backing layer.

[0043] Embodiment 6 is the medical dressing of any of Embodiments 1-5, further comprising a hydrogel island pad adjacent the second major surface of the backing.

[0044] Embodiment 7 is the medical dressing of any of Embodiments 1-6, further comprising a carrier releasably attached to the first major surface of the backing layer.

[0045] Embodiment 8 is the medical dressing according to any one of embodiments 1 to 7, further comprising an antibacterial agent.

[0046] Embodiment 9 is the medical dressing of 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, peroxide, antibiotics, and combinations of the foregoing.

[0047] Embodiment 10 is a medical dressing according to any one of embodiments 1 to 9, wherein the thermochromic indicator is incorporated into or located on a backing layer, adhesive, release liner, support material, hydrogel island pad, or carrier.

[0048] Embodiment 11 is a medical dressing according to embodiment 10, wherein the thermochromic indicator migrates from the carrier to the backing layer upon removal of the carrier.

[0049] Embodiment 12 is a medical dressing according to embodiment 10, wherein the thermochromic indicator is printed on the medical dressing.

[0050] Embodiment 13 is a medical dressing according to 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.

[0051] Embodiment 14 is a method comprising providing the medical dressing of any of Embodiments 1-13, applying the medical dressing to a mammalian body, and detecting a color change resulting from an injection into the mammalian body.

[0052] Embodiment 15 is the method of embodiment 14, wherein a color change indicates IV fluid infiltration.

[0053] Embodiment 16 is the method of either embodiment 14 or 15, further comprising inserting a hypodermic needle or cannula through the skin of the mammalian body covered by the medical dressing or into a blood vessel of the mammalian body.

[0054] The following examples are intended to illustrate, but not limit, the present disclosure. [Example]

[0055] The 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.

[0056] Example 1 Thermochromic fabric coating solutions with a color transition from blue to colorless at 31°C, black to colorless at 28°C, and green to yellow at 25°C were obtained from Atlanta Chemical Engineering LLC (Tampa, FL). Each solution was coated onto the polyurethane film side of a 10-inch wide adhesive laminate consisting of polyurethane film, adhesive, and a release liner (3M Company, St. Paul, MN) using a Mayer rod (size 28) and allowed to dry overnight. Each dye-coated sample was then cut into 2-inch x 2-inch dressing samples. Two dressing samples were made for each coated dye-coated sample, for a total of six dressing samples.

[0057] Freshly euthanized, young adult female cross-breed farm pigs (Yorkshire X from Midwest Research Swine, Gibbon, MN) weighing 10 kg to 40 kg with minimal skin pigmentation and no previous experimental treatment were used. To minimize complications, hair and dirt on the pig's skin at the intended application site were removed prior to the study. A heating blanket (3M Company, St. Paul, MN) was used to maintain the pig's body temperature throughout the study. A pair of each coated dressing was applied to the pig's abdomen prior to euthanasia.

[0058] After euthanasia, the pigs were injected with room-temperature 0.9% sodium chloride injection (Patterson Veterinary, Loveland, CO) intravenously and subcutaneously through either an 18-gauge or 20-gauge needle (Becton-Dickinson, Franklin Lakes, NJ) under each pair of dressings. Saline was injected at 2 mL increments every 10 seconds up to 12 mL. The blue-to-colorless dressings began to change color after 2 mL to 4 mL of subcutaneous injection. The black-to-colorless dressings also changed color after 2 mL to 4 mL of saline injection. Each dressing was initially colorless after application, but the lower temperature saline solution caused a localized change from colorless to blue and black, respectively. Subcutaneous injections produced a diffuse, oval-shaped color change. Intravenous injections produced a narrow, linear band of color. The remaining dressing, which was coated from green to yellow with the dye at 25°C, did not change during the experiment. Temperature data were collected using an IR camera (Teledyne FLIR, Wilsonville, OR) and showed that the observed color change correlated with changes in surface temperature.

[0059] Example 2 A thermochromic fabric coating solution (transition from blue to colorless at 31°C, Atlanta Chemical Engineering LLC, Tampa, FL) was coated onto the polyurethane film side of an 8-inch wide adhesive laminate consisting of polyurethane film, adhesive, and a release liner (3M Company, St. Paul, MN) using a Mayer rod (size 8), then dried in an oven at 150°F for 2 minutes. The dye-coated sample was then cut into 5.5 inch x 5.5 inch squares to obtain experimental dressing samples.

[0060] Freshly euthanized, young adult female cross-breed farm pigs (Yorkshire X from Midwest Research Swine, Gibbon, MN) with minimal skin pigmentation, weighing 10 kg to 40 kg, and no previous experimental treatments were used in this study. To minimize complications, hair and dirt on the pig's skin at the intended application site were removed prior to the study. A heating blanket (3M Company, St. Paul, MN) was used to maintain the pig's body temperature throughout the study. A 20-gauge x 1 (1 / 4)" INTROCAN Safety catheter (B. Braun, Bethlehem, PA) was inserted into the right abdominal region of the pig for subcutaneous injection, and then a dye-coated dressing sample was applied to cover the catheter. Upon application of the dressing to the skin surface, the dressing became colorless. Sodium chloride injection (0.9%) (Patterson Veterinary, Loveland, CO) was infused subcutaneously into the pig using an infusion pump (Baxter, Deerfield, IL) at a flow rate of 100 ml / hr to simulate infiltration. The dressing began to turn blue with approximately 2 ml to 3 ml of saline injection near the tip of the catheter, forming a diffuse ovoid area beginning at the site of the catheter tip.

[0061] Example 3 Polyvinylpyrrolidone K90, with a molecular weight of approximately 1,570,000 g / mol, supplied by Ashland Chemical (Wilmington, Delaware), was added to purified water to prepare a 2 wt% aqueous solution. A thermochromic black-to-colorless dye powder with a thermal transition at 28°C (Atlanta Chemical Engineering LLC, Tampa, FL) was added to a pre-prepared 2 wt% aqueous polyvinylpyrrolidine solution to produce dye concentrations ranging from 0.6 wt% to 3 wt%. White SONTARA nonwoven fabric, supplied by Glatfelte (Charlotte, NC), was immersed in the dye-polyvinylpyrrolidine solution for 5 minutes, then removed and air-dried. This SONTARA, containing a dye and adhesive laminate (3M Company, St. Paul, MN), consisting of a polyurethane film and an acrylate adhesive, was fabricated into experimental dressing prototypes.

[0062] Freshly euthanized, young adult female cross-breed farm pigs (Yorkshire X from Midwest Research Swine, Gibbon, MN) with minimal skin pigmentation, weighing 10 kg to 40 kg, and no previous experimental treatments were used in this study. To minimize complications, hair and dirt on the pig's skin at the intended application site were removed prior to the study. A heating blanket (3M Company, St. Paul, MN) was used to maintain the pig's body temperature throughout the study. A 20-gauge x 1 (1 / 4)" Introcan Safety Catheter (B. Braun, Bethlehem, PA) was inserted into the right abdominal region of the pig for subcutaneous injection, and then the experimental dressing sample was applied to cover the insertion site. The dressing turned white when the dressing was applied, and 0.9% sodium chloride injection (Patterson Veterinary, Loveland, CO) was infused subcutaneously into the pig at a flow rate of 100 ml / hr to simulate infiltration. Approximately 3 ml to 4 ml of saline solution was injected near the tip of the catheter, and the dressing began to turn from gray to black.

[0063] Example 4 Thermochromic dye powder (Atlanta Chemical Engineering LLC, Tampa, FL) was added to an acrylic pressure-sensitive adhesive in a 1:1 ratio of ethyl acetate and heptane (3M Company, St. Paul, MN) at the concentrations shown in Table 1, mixed, and then coated onto a primed 1 mil PET film (3M Company, St. Paul, MN). The coated film was then dried at 70°C for 10 minutes to yield a dry pressure-sensitive adhesive containing the dye approximately 1 mil thick. The adhesive was then laminated to a PELLETHANE 5863-86A-VG film backing (Lubrizol, Wickliffe, OH) to provide an adhesive film construction with the thermochromic dye in the adhesive.

[0064] Test specimens measuring 2.54 centimeters by 12.7 centimeters were cut from each adhesive film construction. The PET liner was removed from the adhesive, and each specimen was laminated to a test panel by placing the adhesive side of the specimen on the test panel and laminating with two passes of a 5-pound roller in each direction. The test panel was #320 stainless steel. Peel tests were performed at room temperature using a Zwick tensile tester (Z005) equipped with a 50 kg load cell at a separation rate of 30.5 centimeters per minute. Each test was performed in triplicate. Reported results are the average of three measurements, reported as oz / inch, and are summarized in Table 1.

[0065] [Table 1]

[0066] Example 5 Thermochromic dye powder (Atlanta Chemical Engineering LLC, Tampa, FL) was added to water along with polyglycerol, hydroxypropyl guar (Solvay, Princeton, NJ), and gamma-irradiated polyvinylpyrrolidone K90 (Ashland, Wilmington, DE). This mixture was then hot-pressed into a 30-mil thick gel sheet containing 0.85 wt% dye. The gels exhibited a color change with temperature, from dark blue to light blue or black to light gray.

[0067] Example 6 A thermochromic coating solution (Atlanta Chemical Engineering LLC, Tampa, FL) containing a thermochromic dye with a black-to-colorless transition at 28°C was Mayer rod (size 20) coated onto the polyurethane film side (ESTANE 58237 TPU, Lubrizol, Wickliffe, OH) of an 8-inch-wide adhesive laminate consisting of polyurethane film, adhesive, and a release liner (3M Company, St. Paul, MN), and then dried in an oven at 150°F for 2 minutes. This black dye-coated adhesive laminate was then Mayer rod (size 20) coated with a second thermochromic coating solution and dried in an oven at 150°F for 2 minutes. The dye in the second thermochromic coating solution had a blue-to-colorless transition at 31°C. This two-layer dye-coated sample was cut into 1-inch by 1-inch pieces and used to obtain a color change vs. temperature curve.

[0068] A 1" x 1" sample was placed on a hot plate and the temperature was increased from 25°C to 40°C. Two videos were taken simultaneously, one recorded with a digital camera to capture color changes and one with a thermal camera to capture temperature changes. For each video, a box selection was made for the background (corner of the plate) and the center of each sample square. Color values ​​were then averaged within that selection. Each video pair was synchronized.

[0069] To obtain a metric of perceived color change, the Euclidean distance of the dressing color from the background is calculated in the CIELAB color space. The CIELAB color space was designed to be perceptibly uniform to the human eye and has undergone various modifications and weightings over the years to handle various color applications and new corrections. The distance in this color space is a useful quantitative measure for determining the amount of dressing color change, how different the dressing color is from a steady background, and for informing how easily the dressing color change can be detected by an observer.

[0070] Color change was calculated in the following manner. Both visible and thermal images were recorded for the heated and cooled dressings. Regions of interest were selected within the video frames, including sections of the dressing sample and the white background. Captured frames from the visible camera were converted to CIELAB color space using the OpenCV Python package and averaged for each region of interest. In CIELAB color space, the Euclidean distance between the background color and the dressing sample 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 is plotted on the y-axis, and the associated temperature is plotted on the x-axis. This information can be used to quantify the perceptible color change as the dressing temperature changes and to compare between dressings with different transition temperatures and different color schemes.

[0071] The experimental dressing has two transition temperatures, one near 29°C and the other near 33°C.

[0072] Example 7: UV-cured gel A mixture of 8.1 g of poly(ethylene glycol) methyl ether acrylate having an average molecular weight of 480 (SIGMA-ALDRICH, St. Louis, MO), 5.9 g of 4-hydroxybutyl acrylate (BASF, Palmyra, MO), 4.0 g of a mixed dodecyl acrylate blend, 0.027 g of Irgacure 2959 photoinitiator, 0.009 g of Irgacure 819 photoinitiator, and 0.18 g of a thermochromic pigment (transition from black to colorless at 28°C) powder (Atlanta Chemical Engineering LLC, Tampa, FL) was mixed on a vibrating table for at least 24 hours. The mixed dodecyl acrylate blend was prepared according to Example 9 of U.S. Pat. No. 9,102,774 (Clapper et al.). The mixture was then coated between two silicone-coated polyester release liners and cured to yield a cured adhesive film approximately 0.25 mm thick. Curing was performed for approximately 30 minutes using ultraviolet (UV) radiation under a sealed bank of six bulbs from a 350-type Blacklight F15TB / 350BL 15W (SYLVANIA brand). The cured samples were nearly opaque and black at room temperature. After heating in a 60°C oven for 10 minutes, the samples turned translucent white. The translucent samples were sufficiently transparent that printed text could be seen through the gel.

[0073] Example 8: A mixture of 8.1 g of poly(ethylene glycol) methyl ether acrylate having an average molecular weight of 480 (SIGMA-ALDRICH, St. Louis, MO), 5.9 g of 4-hydroxybutyl acrylate (BASF, Palmyra, MO), 4.0 g of a mixed dodecyl acrylate blend, 0.027 g of Irgacure 2959 photoinitiator, and 0.009 g of Irgacure 819 photoinitiator was mixed on a vibrating table for at least 24 hours, then coated between two silicone-coated polyester release liners and cured. Curing was carried out for approximately 30 minutes using ultraviolet (UV) radiation under a sealed bank of six bulbs from a 350-type F15TB / 350BL 15W (SYLVANIA brand) black light.

[0074] Two gel layers were prepared using the above procedure: one 0.075 mm thick and the other 0.25 mm thick. The thick layer of gel was then pattern-coated with a thermochromic paint solution (black to colorless at 28°C, Atlanta Chemical Engineering LLC, Tampa, FL) by screening. The screen was a 50-micron-thick polyester release liner with a 20% open area and multiple 2.2 mm diameter holes. After coating, the sample was dried in an oven at 60°C for 60 minutes. The thin gel layer was then laminated to the screen-printed side of the thick gel sample to create a multilayer gel with a dry pigment layer between the two gel layers. A 0.9-mil thick polyurethane film of ESTANE 58237® TPU (Lubrizol, Wickliffe, OH) was then laminated to the back of the thicker gel layer. At room temperature, the sample was transparent with black dots within it. After heating in an oven at 60°C for 10 minutes, the dried paint dots turned translucent white.

[0075] All references and publications cited herein are expressly incorporated by reference in their entirety into this disclosure. 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 illustrated in connection with one exemplary embodiment may be used in connection with other embodiments of the present invention. These and other variations and modifications of 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 described herein. Therefore, the present invention should be limited only by the claims provided below and their equivalents.

Claims

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

2. 10. The medical dressing of claim 1, wherein the thermochromic indicator is a dye, colorant, ink, or pigment.

3. 3. The medical dressing of claim 1, wherein the thermochromic indicator is a dye.

4. The medical dressing according to any one of claims 1 to 3, which is an IV site dressing.

5. 5. The medical dressing of claim 1, further comprising a support material secured to the backing layer, the support material being less elastic than the backing layer.

6. The medical dressing of any one of claims 1 to 5, further comprising a hydrogel island pad 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 antibacterial agent.

9. 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 of the foregoing.

10. 10. The medical dressing of claim 1, 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. 11. The medical dressing of claim 10, wherein the thermochromic indicator migrates from the carrier to the backing layer upon removal of the carrier.

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

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

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

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

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