MEDICAL ARTICLE FOR THE PROPHYLAXIS OF DECUBITUS ULCERS
20230049297 · 2023-02-16
Inventors
Cpc classification
A61F13/0206
HUMAN NECESSITIES
International classification
Abstract
The present invention relates to a medical article (10) for the prophylaxis of the formation and/or worsening of decubitus ulcers, containing a compress (12) and a skin contact layer (13), which skin contact layer can adhere to skin to be treated, wherein the compress (12) has a proximal surface and a distal surface and comprises a core (15) and a shell (14) surrounding the core (15); wherein the core (15) has a proximal surface and a distal surface and comprises a nonwoven material, which is composed of fibers and absorbent particles, wherein the compress (12) has a longitudinal direction having a first modulus of elasticity and a transverse direction having a second modulus of elasticity and the first modulus of elasticity is greater than the second modulus of elasticity.
Claims
1. A medical article (10) for prophylaxis of the development and/or worsening of decubitus ulcers, comprising a compress (12) and a skin-contact layer (13) adhesive to skin to be treated, wherein the compress (12) has a proximal surface and a distal surface and comprises a core (15) and a shell (14) surrounding the core (15), wherein the core (15) has a proximal surface and a distal surface and comprises a nonwoven material composed of fibers and absorbent particles, wherein the compress (12) has a longitudinal direction having a first modulus of elasticity and a transverse direction having a second modulus of elasticity and the first modulus of elasticity is greater than the second modulus of elasticity.
2. The medical article (10) of claim 1, wherein the shell (14) comprises a first ply composed of a liquid-permeable material arranged on the proximal surface of the core (15) and a second ply composed of a material different from the material of the first ply of the shell (14) arranged on the distal surface of the core (15), wherein the first ply of the shell (14) projects beyond the proximal surface of the core (15) on all sides and the second ply of the shell (14) projects beyond the distal surface of the core (15) on all sides, and wherein the first ply of the shell (14) and the second ply of the shell (14) each form an edge region (16) which surrounds the core (15) on all sides, wherein the first ply of the shell (14) and the second ply of the shell (14) are joined to one another in said edge region (16).
3. The medical article (10) of claim 1, wherein the core (15) has an absorption capacity of from 100 g/100 cm.sup.2 to 5000 g/100 cm.sup.2.
4. The medical article (10) of claim 2, wherein the first ply of the shell (14) comprises a first material having hydrophilic properties and in that the second ply of the shell (14) comprises a second material having hydrophobic properties.
5. The medical article (10) claim 2, wherein both the first ply and the second ply of the shell (14) each comprise a material having thermoplastic properties.
6. The medical article (10) of claim 5, wherein the second ply of the shell (14) comprises a thermoplastic material having hydrophobic properties and the first ply of the shell (14) comprises a thermoplastic material which is the same material as that of the second ply of the shell (14) and has been treated in a chemical and/or physical process such that it has hydrophilic properties.
7. The medical article (10) of claim 5, wherein the first ply of the shell (14) and the second ply of the shell have been joined to one another in a thermal process and therefore have a weld connection (18) to one another.
8. The medical article (10) of claim 7, wherein the weld connection (18) comprises at least one discontinuous weld line (19).
9. The medical article (10) of claim 8, wherein the weld connection (18) comprises four to six parallel discontinuous weld lines (19).
10. The medical article (10) of claim 8, wherein the at least one discontinuous weld line (19) is oriented parallel to the machine direction in the production process.
11. The medical article (10) of claim 1, wherein the skin-contact layer (13) adhesive to skin to be treated comprises a ply of a skin-friendly silicone adhesive (13b).
12. The medical article (10) of claim 1, wherein the skin-contact layer (13) has openings, the total open area of which is between 10% and 25% of the total surface area of the skin-contact layer (13).
13. The medical article (10) of claim 1, wherein the skin-contact layer (13) has openings (13c) having a substantially circular shape, the average diameter of which is between 0.2 mm to 3.0 mm.
14. The medical article (10) of claim 1, wherein the article comprises an additional outer ply (11) having a proximal and a distal surface, wherein the additional outer ply (11) comprises a water vapor-permeable and substantially liquid-impermeable film material.
15. The medical article (10) of claim 1, wherein the proximal surface of the additional outer ply (11) comprises a coating containing a pressure-sensitive adhesive and the additional outer ply (11) projects beyond the distal surface of the compress (12) on all sides, so that it forms an adhesive edge region (17) which surrounds the compress (12) on all sides.
16. The medical article (10) of claim 1, wherein the additional outer ply (11) projects beyond the distal surface of the compress (12) on all sides and the skin-contact layer (13) is coextensive with the outer ply (11).
17. The medical article (10) of claim 1, wherein the article (10) comprises an element suitable for marking the material direction having a higher modulus of elasticity.
18. A method for the prophylaxis of the development and/or worsening of decubitus ulcers comprising employing the medical article (10) of claim 1.
19. A method for production of a medical device for prophylaxis of the development and/or worsening of decubitus ulcers comprising employing the medical article (10) of claim 1.
Description
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EXAMPLES
Example 1 Medical Article
[0096] The medical article comprises a compress, an additional outer ply, and a skin-contact layer adhesive to skin to be treated. The compress comprises a core and a shell. The shell is formed by a proximal ply and a distal ply. The skin-contact layer is formed from a perforated sheet material and a ply of a skin-friendly silicone adhesive. The outer ply is formed from a water vapor-permeable and liquid-impermeable polyurethane film material having low frictional properties and a thickness of 30 .Math.m.The core comprises a blend of cellulose fibers and superabsorbent sodium polyacrylate particles in a prefabricated airlaid material. The core also comprises a diffusion layer in the form of a ply of a cellulose paper wrapped around the airlaid blend of cellulose fibers and polyacrylate particles. The proximal ply of the shell is a nonwoven material composed of a blend of viscose fibers and polyamide fibers. The distal ply of the shell is a nonwoven material composed of polypropylene fibers. The perforated sheet material of the skin-contact layer consists of a polyurethane film which has openings having a circular shape. Said openings have a uniform shape having an average diameter of 2.4 mm and are arranged in a regular pattern such that the proportion of open area is 15%. The skin-contact layer additionally comprises a ply of a skin-friendly silicone adhesive without closing the openings of the perforated sheet material at the same time.
Example 2 Test Solutions Used for Characterization of Medical Dressings
[0097] Solution A (saline solution) [0098] 2 L of deionized water [0099] 0.74 g of calcium chloride dihydrate (CaCl.sub.2 .Math.2 H.sub.2O, CAS: 10035-04-5) [0100] 16.6 g of sodium chloride (NaCl, CAS: 7647-14-5)
[0101] Solution B (exudate solution) [0102] 1 L of deionized water [0103] 70 g of albumin from chicken egg white (CAS: 9006-59-1) [0104] 0.2 g of Allura Red AC (CAS: 25956-17-6) [0105] 9 g of sodium chloride (NaCl, CAS: 7647-14-5) [0106] 0.37 g of calcium chloride dihydrate (CaCl.sub.2 .Math.2 H.sub.2O, CAS: 10035-04-5) [0107] 2 g of methyl 4-hydroxybenzoate (CAS: 99-76-3) [0108] 1 g of propyl 4-hydroxybenzoate (CAS: 94-13-3)
Example 3 Rate of Absorption
[0109] The rate of absorption of an article is determined by the time required for complete absorption of a test liquid. Test solutions can be either saline solution (solution A) or exudate solution (solution B). Both the solutions and the test specimens must be preconditioned at room temperature before the test by storage of the test specimens and the solutions at 22° C. for two hours.
[0110] A 50 mL burette is filled with test solution. The liquid level is set at 15 mL. A test specimen is placed under the burette, the surface facing the burette being that which faces the skin when using the article. The distance between burette and test specimen is set at 1 cm. The burette tap is opened, while a stopwatch is simultaneously started. 2 mL of the test solution are allowed to flow out of the burette. The stopwatch is stopped once 2 mL of the test solution have been completely absorbed by the article, i.e., when there is no longer a drop of the test solution remaining on the perforation of the skin-contact layer. If the test specimen is sufficiently large, 1 to 3 measurements can be made on the same article. In this case, the test positions are in the center and two more points along a diagonal toward the corners of the article; they correspond to the positions of the spots of number 3 on a standard dice. At least five samples are tested.
[0111] Each value is classified in the following way:
TABLE-US-00001 Time (s) [0 to 4.9] [5.0 to 10.9] [11.0 to 30.9] [31.0 to 60.0] >60 Category Immediately Very rapid Rapid Average Slow
[0112] An article according to the present invention was compared with the commercially available dressings Biatain® silicone, Allevyn® Life and Mepilex® border.
[0113] Rate of absorption
TABLE-US-00002 Article Rate of Absorption Rate [proportion of samples] Immediately Very rapid Rapid Average Slow Example 1 20% 80% 0% 0% 0% Biatain® silicone 0% 0% 0% 20% 80% Allevyn® Life 0% 0% 100% 0% 0% Mepilex® border 0% 0% 0% 100% 0%
Example 4 Absorption Capacity
[0114] Both the solutions used (saline solution or exudate solution) and the test specimens must be preconditioned at room temperature before the test by storage thereof at a temperature of 22° C. for two hours.
[0115] The basic mass m.sub.1 of an article is determined after removal of the protective layer covering the skin-contact layer. The length and width of the core of the compress is determined, so that the surface area S of the core of the compress can be determined. A bowl is filled with test liquid. The mass of the test solution should be at least 40 times greater than that of the article. The article is dipped into the bowl, while a stopwatch is simultaneously started. The side of the article that faces the skin in use should face the bottom of the bowl, and the reverse side of the article should be at the top. The article should not adhere to the bottom of the bowl. The article is left in the bowl for 30 min +/- 1 min. The dressings should only be touched at their edges and not at the core of the compress itself. The dressings are fixed in a clip at one corner and left hanging at room temperature for 20 min. The wet mass m.sub.2 of the article is determined. The amount of absorbed test solution m.sub.liquid is calculated as follows: m.sub.liquid = m.sub.2 - m.sub.1
[0116] The absorption capacity is the quotient from the amount of absorbed test solution divided by the surface area S of the core of the compress, having the unit g/100 cm.sup.2.
[0117] Absorption capacity = (m.sub.2-m.sub.1/S)*100
[0118] An article according to the present invention was with the commercially available dressings Biatain® silicone, Allevyn® Life and Mepilex® border.
[0119] Comparison of absorption capacities:
TABLE-US-00003 Article Absorption Capacity in g/100 cm.sup.2 Example 1 147 Biatain® silicone 116 Allevyn® Life 87 Mepilex® border 54
Example 5 Adherence Power
[0120] Test subjects were informed about the purpose of the test and gave their written consent. Test products were applied to the back of each individual test subject (two samples per test product): One sample of each test product was secured on the top half of the back. The second sample was secured on the bottom half of the back.
[0121] The bottom end of each sample was folded over at a distance of 0.5 cm from the bottom edge in order to provide a starting point for pulling off the sample from bottom to top using a universal testing machine. The samples were applied by trained personnel and pressed onto the subject’s skin with the aid of a metal roller (1 kg, rolling back and forth five times).
[0122] The test subjects arrived at the study site 3 hours and 50 minutes after sample application and stayed in an air-conditioned room for at least 10 minutes. A check was made to determine that the subjects were not sweating. 4 hours after application of the samples, the samples were pulled off by means of a universal testing machine to determine the adherence power.
[0123] Universal testing machine: Zwick 1120 (Zwick GmbH, Ulm, Germany). The universal testing machine measures the force required to detach the samples from a test subject’s skin. To detach the samples, the test subjects were placed in a sitting position. The samples were pulled off at an angle of approximately 135°. One measurement was made for each sample, and two samples were tested from each product.
Example 6 Weld Strength
[0124] Weld strength is determined using an MTS C42.503E tensile tester instrument (MTS Systems Corporation, Eden Prairie, USA) at a cell strength of 50 N.
[0125] Samples were prepared by punching out a portion of the core of the compress that contains a weld line and has a rectangular shape 15 mm wide and 25 mm long, the 15 mm side corresponding to the weld line. The sample must be taken at least 2 mm from the corner of the product. After the punch-out procedure was carried out, the core material was removed, leaving only a piece composed of two nonwoven materials joined to one another. The grips of the tester were set such that the distance between them was 2 cm. The two nonwoven pieces were clamped in separate grips. The tester was started at a speed of 200 mm/min until the two nonwoven pieces were separated from one another.
[0126] The weld strength is the average strength over the test period. It is reported in N/15 mm.
Example 7 Tensile Strength
Sampling
[0127] Test specimens corresponding to type 5a in accordance with DIN ISO 527, the shape of which is reproduced in
[0127] TABLE-US-00004 l.sub.1 Length of narrow parallel portion 25 ± 1 l.sub.3 Overall length ≥ 75 b.sub.1 Width of narrow portion 4 ± 0.1 b.sub.2 Width at ends 12.5 ± 1 r.sub.1 Small radius 8 ± 1 r.sub.2 Large radius 12.5 ± 1 L Initial distance between grips 50 ± 2 L.sub.0 Gauge length 20 ± 0.5
[0128] Test specimens were taken both in a direction parallel to the machine direction of the production process and in a direction perpendicular to the machine direction of the production process.
Cyclic Tensile Testing
[0129] The mechanical properties of the punched samples were tested in a cyclic tensile test at a test temperature of 35° C. by means of a Z005 universal testing machine from Zwick/Roell with a temperature chamber. The samples were strained twice up to a nominal strain of 15% and then unloaded and subsequently tested to break.
Test Procedure
[0130] Measuring device: Zwick/Roell Z005 (max. 5 kN) [0131] Load cell: 500 N [0132] Displacement transducer: Crosshead [0133] Free clamping length of the sample: lo = 50 mm [0134] Preload: 0.1 N (measurement begins after the preload has been reached (load = 0; displacement = 0)) [0135] Test speed until the preload is reached: 5 mm/min [0136] Test speed: 50 mm/min [0137] Number of loading and unloading cycles: 2 Ls [0138] Cyclic loading: Up to 15% nominal strain s.sub.0 [0139] Holding time at 15% nominal strain: 1 second [0140] Measured values: Force F and crosshead displacement Δs [0141] Test temperature: 35° C. [0142] Test atmosphere: Air
Preparation of the Test Specimens by Stamping
[0143] Sample: Waisted tensile sample type 5A (DIN EN ISO 527-2:2012-06) Sample width: 4.1 mm
Measuring Device For
[0144] measuring thickness: HEIDENHAIN N221 measurement sensor
[0145] In the tensile test, the forces and deformation displacements were measured and presented as force-displacement graphs for the various samples tested.
[0146] The modulus of elasticity is defined as the slope of the graph in the stress-strain graph:
[0147] Modulus of elasticity E = σ / ε
[0148] with stress σ and strain ε.
[0149] Here, σ = F / A refers to the mechanical stress force per cross-sectional area of the test specimen.
[0150] Here, ε = Δl/ l.sub.0 with change in length Δl = l - l.sub.0 refers to the strain, I referring to the length of the test specimen after the tensile test and l.sub.0 referring to the initial length of the test specimen.
[0151] What were tested were both test specimens that were taken in a direction parallel to the machine direction of the production process and test specimens that were taken in a direction perpendicular to the machine direction of the production process. The moduli of elasticity thereof were ratioed with one another to calculate the anisotropy of the respective materials.
[0152] The following table lists the thus determined anisotropies with respect to the moduli of elasticity of the individual components of a medical article according to example 1:
TABLE-US-00005 Ply Anisotropy Outer ply 1.1 Compress 2.5 Nonwoven material 3.7 Distal ply of the shell 2.4 Skin-contact layer 0.9
Example 8 Compression
Cyclic Compression Test
[0153] The mechanical properties of the products were tested in the dry state and in the waterwetted state in a cyclic compression test at a test temperature of 35° C. by means of a Z005 universal testing machine from Zwick/Roell with a temperature chamber. The samples were compressed twice up to a load of 150 N and then unloaded and subsequently tested up to a maximum of 450 N.
Test Procedure
[0154] Measuring device: Zwick/Roell ZOOS (max. 5 kN) [0155] Load cell: 500 N [0156] Displacement transducer: Crosshead [0157] Preload: 0.1 N (measurement begins after the preload has been reached (load = 0; displacement = 0)) [0158] Test speed until the preload is reached: 2 mm/min [0159] Test speed: 2 mm/min [0160] Number of loading and unloading cycles: 2 [0161] Cyclic loading: Up to 150 N load [0162] Holding time at 150 N: None [0163] Measured values: Force F and crosshead displacement Ds Distance between the compression platens at preload (= initial gauge length) [0164] Compression platens: Steel, dry (diameter = 60 mm) [0165] Test temperature: 35° C. [0166] Test atmosphere: Air
Preparation of the Test Specimens
[0167] Sample: Patch was adhesively bonded on lower compression platen at the center and in a dry or wet (wetted with water) state Wetting: Distilled water (0.15 mL/cm.sup.2) - an amount of water corresponding to the sample area was applied to the product surface facing away from the skin using a pipette and allowed to soak in for one hour, after which the test was carried out.
Example 9 Coefficient of Friction
Friction Tests
[0168] Using a rotary tribometer, the samples were tested in the dry and wetted state for their frictional behavior in relation to a cotton surface. Wetted means that the sample has been wetted at the surface on the top layer using 0.15 ml/cm.sup.2 distilled water. An amount of water corresponding to the sample area was applied to the patch surface using a pipette and allowed to soak in for one hour, after which the test was carried out. To this end, the sample is adhesively bonded to a stationary, flat steel surface (diameter 60 mm). The rotating counter partner is a cotton fabric which has been adhesively bonded to a steel stamp (diameter 60 mm) by means of double-sided adhesive tape. The sample and the counter surface are pressed against one another with a contact force of 50 N, and then the coefficient of friction between sample and rotating counter surface is measured at different sliding speeds.
[0169] The drive motor rotates at different defined rotational speeds corresponding to a sliding speed of from 1 mm/s to 100 mm/s. The sliding speed is calculated on the basis of the average diameter of 30 mm.
Test Procedure
[0170] Measuring device: Self-made rotary tribometer [0171] Force-torque sensor: Max. 100 N [0172] Preload: 50 N (static) corresponds to normal load [0173] Stamp diameter of the friction contact surfaces: 60 mm [0174] Counter partner: Cotton [0175] Sliding speed v for average stamp diameter d = 30 mm: Variable, 1 mm/s to 100 mm/s [0176] Rotational speed n: Variable depending on sliding speed, [0177] Speed profile: 15 levels, see table [0178] Number of samples: 3 each [0179] Test temperature: 23° C. (room temperature) [0180] Test atmosphere: Air
TABLE-US-00006 Test conditions of the friction tests Level Sliding speed v for 30 mm diameter [mm/s] Rotational speed n [rpm] Time span Δt [s] Time t [s] 1 0.0 0.00 5 5 2 0.2 0.13 5 10 3 0.0 0.00 5 15 4 1.0 0.64 100 115 5 5.0 3.18 20 135 6 10 6.37 10 145 7 20 12.74 10 155 8 30 19.11 10 165 9 40 25.48 10 175 10 50 31.85 10 185 11 60 38.22 10 195 12 70 44.59 10 205 13 80 50.96 10 215 14 90 57.32 10 225 15 100 63.69 10 235
[0181] The medical dressings tested had the following coefficients of friction (COF): Adhesive friction (dry) COF.sub.dry = 0.36 Adhesive friction (wetted) COF.sub.wetted = 0.41 Sliding friction (dry) COF.sub.dry = 0.28 Sliding friction (wetted) COF.sub.wet = 0.36
Example 10 Finite Element Method (FEM)
[0182] The FEM is a general and computer-aided numerical method used for different physical problems. The FEM is logically based on numerically solving a complex system of differential equations. The FEM divides large problems into a multitude of smaller parts called finite elements. Analysis is carried out with each of these elements and, taken as a whole, results in a solution for the entire problem.
[0183] The work steps of an FEM can be described as follows: [0184] 1. creation of a 2D or 3D model consisting of finite elements; [0185] 2. definition of the material properties of the model; [0186] 3. definition of the boundary conditions and loads for application of the model to the problem; [0187] 4. computer-aided solving of the problem; and [0188] 5. analysis of the results through visualization and calculation.
[0189] The FEM calculation underlying the invention was done according to the method described in the following article: Levy A, Schwartz D, Gefen A. The contribution of a directional preference of stiffness to the efficacy of prophylactic sacral dressings in protecting healthy and diabetic tissues from pressure injury: computational modelling studies. Int Wound J 2017; doi: 10.111/iwj.12821
[0190] To understand the effects of medical dressings according to the present invention, FE models of a human pelvis and the dressings were created. The influences of pressure and stress on the skin and deeper tissues were analyzed.
[0191] The pelvic model was based on MRI scans of a voluntary female test subject in order to ensure the greatest possible anatomical accuracy of the model.
[0192] The FE models comprise 3 900 000 nodes.
[0193] Soft tissues were represented as nonlinear materials, with muscles being amalgamated to form one material and fat and skin each being amalgamated as compressible materials. The bones were amalgamated as a rigid body.
[0194] Modeling was based on the following material properties:
[0195] Bed: Linear modulus of elasticity E = 50 kPa Bone: Linear modulus of elasticity E = 7000 MPa Adipose tissue: Hyperelasticity (neo-Hooke) C10 = 0.0004 Muscle tissue: Hyperelasticity (neo-Hooke) C10 = 0.000225 Skin: Hyperelasticity (neo-Hooke) C10 = 0.004
[0196] A relevant model volume (volume of interest, VOI) having dimensions of 6.7 cm x 2.0 cm x 5.1 cm (x-direction x y-direction x z-direction) was formed, containing the sacrum (os sacrum) and the surrounding soft tissue including skin.
[0197] Von Mises stress refers to a fictitious uniaxial stress which, on the basis of a specific material-mechanical or mathematical criterion, represents a hypothetically equivalent material stress, such as a real multiaxial state of stress.
[0198] On the basis of the von Mises stress, the real, generally three-dimensional state of stress in the component in the strength or yield condition can be compared with the characteristics from the uniaxial tensile test (material characteristics, for example yield point or tensile strength).
[0199] The von Mises stresses can be calculated according to the following formula:
[0200] Here, σ.sub.l, σ.sub.ll, and σ.sub.lll are the principal stresses occurring in the three spatial directions.
[0201] What are of particular importance are the stresses occurring on the skin within the relevant model volume, because what occur here are not only the pressures responsible for the development and worsening of decubitus ulcers, but also shearing forces.
[0202] A comparison was made in each case between calculations in which a medical article according to the invention was placed on a skin area with the same skin area without an applied medical article.
[0203] What is of significant interest is the 10% value. This value indicates what maximum stresses occur in not more than 10% of the relevant comparison volume. It corresponds to the curve point associated with the ordinate intercept at 10% VOI.
[0204] From the comparison of the von Mises stresses on the skin in the relevant model volume with and without an applied medical article, suitability for prevention of the development of decubitus ulcers can be postulated if the 10% value for the stresses that occur is reduced by more than 10%.
[0205] The curves shown in
TABLE-US-00007 Curve (A): 21.8239 kPa Article according to the invention Curve (B): 24.3311 kPa Competitor product 1 Curve (C): 24.2884 kPa Competitor product 2 Curve (D): 27.2725 kPa No article applied
[0206] As can be seen from