Patent Publication Number: US-2021177662-A1

Title: Wound dressing with welded elastic structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application No. 62/577,556, filed on Oct. 26, 2017, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to a wound dressing. The present disclosure relates more particularly to a wound dressing having a welded elastic structure to promote substantial elastic deformation and recovery. 
     Substantial elastic recovery may be particularly important for treating tissue in areas of relatively high articulation or flexure, such as proximal to shoulder, elbow, knee, ankle, or hip joints (particularly knee or elbow joints). It may be desirable for a wound dressing to be able to undergo significant local flexure and substantially retain its shape, and its contact with the tissue site, upon significant articulation. Maintaining shape or tissue contact can reduce the frequency of necessitated dressing changes, reduce tissue blistering from improper contact, increase exudate absorption, reduce healing time, increase patient comfort, or combinations thereof. 
     Some wound dressings include an absorbent layer made of a hydrofiber material. Hydrofibers are typically non-woven fibrous materials that include an entanglement of gelling (i.e., absorbent) fibers and non-gelling (i.e., reinforcing) fibers. When a hydrofiber material is stretched, the non-woven fibers pull apart from each other, resulting in plastic deformation. It can be challenging to make a hydrofiber material exhibit elastic recovery, especially when the wound dressing is wet as a result of absorbing wound fluid. For example, any bond of the hydrofiber material to other layers of wound dressing (e.g., a colloid/silicone interface, a backing layer, etc.) may fail when the wound dressing is wet, causing the hydrofiber material to become disassociated with the other layers of the wound dressing. It would be desirable to provide a wound dressing that overcomes these and other limitations of conventional wound dressings. 
     SUMMARY 
     One implementation of the present disclosure is a wound dressing including an inelastic absorbent layer, an elastic film, and a plurality of welds. The inelastic absorbent layer is configured to absorb wound fluid and has a first side and a second, wound-facing side. The elastic film is configured to elastically stretch when a stretching force is applied to the wound dressing and elastically recover when the stretching force is removed. The plurality of welds fix the elastic film to the first side of the inelastic absorbent layer such that the elastic film and the inelastic absorbent layer elastically stretch and elastically recover as a unit. 
     In some embodiments, the elastic film is configured to apply an elastic recovery force to the inelastic absorbent layer via the plurality of welds when the stretching force is removed. The elastic recovery force may cause the inelastic absorbent layer to elastically recover. 
     In some embodiments, the inelastic absorbent layer includes a nonwoven hydrofiber material. In some embodiments, the inelastic absorbent layer includes an entanglement of nonwoven fibers configured to separate from each other when the stretching force is applied. In some embodiments, the inelastic absorbent layer includes an antimicrobial agent. The antimicrobial agent can include antimicrobial silver, silver oxidized regenerated cellulose (ORC) (e.g., approximately 25 wt % ionically bound silver), polyhexamethylene biguanide (PHMB), or other antimicrobial agents, in various embodiments. 
     In some embodiments, the inelastic absorbent layer includes a plurality of cellulosic gelling fibers including at least one of carboxymethyl cellulose, carboxylethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, or cellulose ethyl sulphonate. In some embodiments, the inelastic absorbent layer includes a plurality of reinforcing fibers including at least one of a polyurethane gel, an amide polymer, an olefin polymer, an ester polymer, or a modified acrylamide polymer. 
     In some embodiments, the inelastic absorbent layer includes a plurality of cellulosic gelling fibers and a plurality of reinforcing fibers. In some embodiments, the plurality of cellulosic gelling fibers form between 45% and 90% of the inelastic absorbent layer and the plurality of reinforcing fibers form between 10% and 55% of the inelastic absorbent layer. 
     In some embodiments, the elastic film includes at least one of a polyurethane film or a polyethylene film. In some embodiments, the elastic film has a thickness between 20 microns and 50 microns. 
     In some embodiments, the plurality of welds include radio frequency welds. In some embodiments, the plurality of welds are distributed across the elastic film and the inelastic absorbent layer. In some embodiments, the plurality of welds are distributed non-uniformly such that the plurality of welds cause the wound dressing to elastically stretch and elastically recover non-uniformly. In some embodiments, the plurality of welds comprise spot welds having diameters between 2 millimeters and 3 millimeters. 
     In some embodiments, the wound dressing includes a backing layer adhered to the elastic film layer opposite the inelastic absorbent layer. In some embodiments, the backing layer is substantially impermeable to liquid and substantially permeable to vapor. In some embodiments, the backing layer extends beyond a perimeter of the elastic film and the inelastic absorbent layer to provide an adhesive-coated margin configured to adhere the wound dressing to a surface. 
     In some embodiments, the wound dressing includes a non-adherent layer coupled to the second, wound-facing side of the inelastic absorbent layer. In some embodiments, the non-adherent layer includes a hydrophobic material. In some embodiments, the non-adherent layer includes at least one of an alkyl acrylate polymer, an alkacrylate polymer, or an alkyl alkacrylate polymer. In some embodiments, the non-adherent layer comprises a plurality of perforations distributed across a surface of the non-adherent layer. 
     In some embodiments, the elastic film is welded to the inelastic absorbent layer in a pre-stretched state such that the elastic film causes the inelastic absorbent layer to collapse when no external forces are applied to the wound dressing. In some embodiments, the elastic film is stretched by approximately 20% of its relaxed length when in the pre-stretched state. 
     In some embodiments, at least one of the elastic film or the inelastic absorbent layer includes a plurality of fenestrations configured to increase a distance that the wound dressing stretches per unit of the stretching force. In some embodiments, the plurality of fenestrations are distributed non-uniformly such that the plurality of fenestrations cause the wound dressing to elastically stretch and elastically recover non-uniformly. 
     In some embodiments, the wound dressing includes a length defining a size of the wound dressing along a first dimension and a width less than the length and defining a size of the wound dressing along a second dimension substantially perpendicular to the first dimension. In some embodiments, at least one of the elastic film or the inelastic absorbent layer includes a plurality of linear fenestrations aligned with the first dimension or the second dimension. 
     In some embodiments, the plurality of fenestrations are aligned with the first dimension and configured to increase a distance that the wound dressing stretches per unit of the stretching force when the stretching force is applied along the second dimension. In some embodiments, the plurality of fenestrations are aligned with the second dimension and configured to increase a distance that the wound dressing stretches per unit of the stretching force when the stretching force is applied along the first dimension. 
     Another implementation of the present disclosure is a wound dressing including a dressing layer and a backing layer. The dressing layer has a first side and a second, wound-facing side. The dressing layer includes an inelastic absorbent layer and an elastic film. The inelastic absorbent layer is configured to absorb wound fluid and has a first side and a second, wound-facing side. The elastic film is welded to the first side of the inelastic absorbent layer such that the dressing layer elastically stretches when a stretching force is applied to the wound dressing and elastically recovers when the stretching force is removed. The backing layer is adhered to the first side of the dressing layer. 
     In some embodiments, the elastic film is configured to apply an elastic recovery force to the inelastic absorbent layer when the stretching force is removed. The elastic recovery force may cause the dressing layer to elastically recover. 
     In some embodiments, the inelastic absorbent layer includes a nonwoven hydrofiber material. In some embodiments, the inelastic absorbent layer includes an entanglement of nonwoven fibers configured to separate from each other when the stretching force is applied. In some embodiments, the inelastic absorbent layer comprises an antimicrobial agent. The antimicrobial agent can include antimicrobial silver, silver oxidized regenerated cellulose (ORC) (e.g., approximately 25 wt % ionically bound silver), polyhexamethylene biguanide (PHMB), or other antimicrobial agents, in various embodiments. 
     In some embodiments, the inelastic absorbent layer includes a plurality of cellulosic gelling fibers including at least one of carboxymethyl cellulose, carboxylethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, or cellulose ethyl sulphonate. In some embodiments, the inelastic absorbent layer includes a plurality of reinforcing fibers including at least one of a polyurethane gel, an amide polymer, an olefin polymer, an ester polymer, or a modified acrylamide polymer. 
     In some embodiments, the inelastic absorbent layer includes a plurality of cellulosic gelling fibers and a plurality of reinforcing fibers. In some embodiments, the plurality of cellulosic gelling fibers form between 45% and 90% of the inelastic absorbent layer and the plurality of reinforcing fibers form between 10% and 55% of the inelastic absorbent layer. 
     In some embodiments, the elastic film includes at least one of a polyurethane film or a polyethylene film. In some embodiments, the elastic film has a thickness between 20 microns and 50 microns. 
     In some embodiments, the elastic film is welded to the inelastic absorbent layer with radio frequency welds. In some embodiments, the elastic film is welded to the inelastic absorbent layer at a plurality of locations distributed across the dressing layer. In some embodiments, the plurality of locations are distributed non-uniformly such that the dressing layer elastically stretches and elastically recovers non-uniformly. In some embodiments, the elastic film is welded to the inelastic absorbent layer with spot welds having diameters between 2 millimeters and 3 millimeters. 
     In some embodiments, the backing layer is substantially impermeable to liquid and substantially permeable to vapor. In some embodiments, the backing layer extends beyond a perimeter of the dressing layer to provide an adhesive-coated margin configured to adhere the wound dressing to a surface. 
     In some embodiments, the dressing layer includes a non-adherent layer coupled to the second, wound-facing side of the inelastic absorbent layer. In some embodiments, the non-adherent layer includes a includes material. In some embodiments, the non-adherent layer includes at least one of an alkyl acrylate polymer, an alkacrylate polymer, or an alkyl alkacrylate polymer. In some embodiments, the non-adherent layer includes a plurality of perforations distributed across a surface of the non-adherent layer. 
     In some embodiments, the elastic film is welded to the inelastic absorbent layer in a pre-stretched state such that the elastic film causes the inelastic absorbent layer to collapse when no external forces are applied to the wound dressing. In some embodiments, the elastic film is stretched by approximately 20% of its relaxed length when in the pre-stretched state. 
     In some embodiments, at least one of the elastic film or the inelastic absorbent layer includes a plurality of fenestrations configured to increase a distance that the wound dressing stretches per unit of the stretching force. In some embodiments, the plurality of fenestrations are distributed non-uniformly such that the plurality of fenestrations cause the wound dressing to elastically stretch and elastically recover non-uniformly. 
     In some embodiments, the wound dressing includes a length defining a size of the wound dressing along a first dimension and a width less than the length and defining a size of the wound dressing along a second dimension substantially perpendicular to the first dimension. In some embodiments, at least one of the elastic film or the inelastic absorbent layer includes a plurality of linear fenestrations aligned with the first dimension or the second dimension. 
     In some embodiments, the plurality of fenestrations are aligned with the first dimension and configured to increase a distance that the wound dressing stretches per unit of the stretching force when the stretching force is applied along the second dimension. In some embodiments, the plurality of fenestrations are aligned with the second dimension and configured to increase a distance that the wound dressing stretches per unit of the stretching force when the stretching force is applied along the first dimension 
     Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices and/or processes described herein, as defined solely by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a wound dressing with a welded elastic structure, according to an exemplary embodiment. 
         FIG. 2  is a cross-sectional view of the wound dressing of  FIG. 1 , according to an exemplary embodiment. 
         FIG. 3  is a top perspective view of a dressing layer of the wound dressing of  FIG. 1 , according to an exemplary embodiment. 
         FIG. 4  is a top plan view of the dressing layer of  FIG. 3 , according to an exemplary embodiment. 
         FIG. 5  is a side elevation view illustrating a pre-stretching of an elastic film when forming the dressing layer of  FIG. 3 , according to an exemplary embodiment. 
         FIG. 6  is a side elevation view illustrating the pre-stretched elastic film welded to an absorbent layer to form the dressing layer of  FIG. 3 , according to an exemplary embodiment. 
         FIG. 7  is a top perspective view of the dressing layer of  FIG. 3  after the pre-stretched elastic film is welded to the absorbent layer, according to an exemplary embodiment. 
         FIG. 8A  is a top plan view of the wound dressing of  FIG. 1  showing a plurality of fenestrations aligned with a width dimension of the wound dressing and a plurality of welds, according to an exemplary embodiment. 
         FIG. 8B  is a detail view of a portion of  FIG. 8A , according to an exemplary embodiment. 
         FIG. 9A  is a top plan view of the wound dressing of  FIG. 1  showing a plurality of fenestrations aligned with a length dimension of the wound dressing and a plurality of welds, according to an exemplary embodiment. 
         FIG. 9B  is a detail view of a portion of  FIG. 9A , according to an exemplary embodiment. 
         FIG. 10A  is a top plan view of the wound dressing of  FIG. 1  showing a plurality of fenestrations aligned with a width dimension of the wound dressing without the plurality of welds, according to an exemplary embodiment. 
         FIG. 10B  is a detail view of a portion of  FIG. 10A , according to an exemplary embodiment. 
         FIG. 11A  is a top plan view of the wound dressing of  FIG. 1  showing a plurality of fenestrations aligned with a length dimension of the wound dressing without the plurality of welds, according to an exemplary embodiment. 
         FIG. 11B  is a detail view of a portion of  FIG. 11A , according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     Referring generally to the FIGURES, a wound dressing with a welded elastic structure is shown, according to various exemplary embodiments. The wound dressing described herein can be configured to exhibit substantial elastic recovery under wound treatment conditions. Substantial elastic recovery may be particularly important for treating tissue in areas of relatively high articulation or flexure, such as proximal to shoulder, elbow, knee, ankle, or hip joints (particularly knee or elbow joints). It may be desirable for a wound dressing to be able to undergo significant local flexure and substantially retain its shape, and its contact with the tissue site, upon significant articulation. Maintaining shape or tissue contact can reduce the frequency of necessitated dressing changes, reduce tissue blistering from improper contact, increase exudate absorption, reduce healing time, increase patient comfort, or combinations thereof. 
     In some embodiments, the wound dressing includes a plurality of layers including at least an elastic film and an inelastic absorbent layer. The elastic film is welded to the inelastic absorbent layer to form a welded elastic structure. The inelastic absorbent layer is configured to absorb wound fluid and may include an entanglement of non-woven fibers. When subjected to a stretching force, the non-woven fibers of the absorbent layer may pull apart from each other, resulting in plastic deformation of the absorbent layer. The material of the absorbent layer is, in isolation, substantially inelastic, meaning that the absorbent layer does not return to its original shape after application of a stretching force. However, the elastic film is substantially elastic and configured to exhibit substantially elastic deformation and recovery. 
     Advantageously, the elastic film is welded to the absorbent layer, thereby fixing the elastic film to the absorbent layer and imbuing the elastic properties of the elastic film to the absorbent layer. For example, when a stretching force is applied to the wound dressing, both the elastic film and the absorbent layer may stretch together, as a unit. When the stretching force is removed, the elastic film may elastically recover and return to its original shape. Because the elastic film is secured to the absorbent layer, the elastic film may apply an elastic recovery force to the absorbent layer via the plurality of welds when returning to its original shape. The elastic recovery force causes the absorbent layer to elastically recover along with the elastic film. These and other features and advantages of the wound dressing are described in detail below. 
     Wound Dressing 
     Referring now to  FIGS. 1-2 , a wound dressing  100  is shown, according to an exemplary embodiment.  FIG. 1  is an exploded view of wound dressing  100 , whereas  FIG. 2  is a cross-sectional view of wound dressing  100  adhered to a surface  130 . Wound dressing  100  is shown to include a plurality of layers including a backing layer  102 , an elastic film  104 , an inelastic absorbent layer  106 , and a non-adherent layer  108 . Elastic film  104  is welded to absorbent layer  106  via welds  110  to form a welded elastic dressing layer  105 . In some embodiments, wound dressing  100  includes a removable cover sheet to cover absorbent layer  106  and/or non-adherent layer  108  before use. In some embodiments, one or more layers of wound dressing  100  can be omitted. Each layer of wound dressing  100  is described in detail below. 
     Wound dressing  100 , as a whole, can be configured to exhibit substantially elastic recovery under tissue treatment conditions. Absorbent layer  106 , in isolation, may be substantially inelastic and therefore may not exhibit elastic recovery. However, elastic film  104  is substantially elastic and fixed to absorbent layer via welds  110 , thereby imbuing absorbent layer  106  with elastic properties. In this way, elastic film  104  enables absorbent layer  106 , and thus wound dressing  100  as a whole, to exhibit substantially elastic recovery at tissue treatment conditions. This may be a desirable characteristic in combination with the ability to absorb wound fluid, especially when the ability to absorb wound fluid comes mainly from an absorbent layer  106  that does not exhibit substantial elastic recovery in isolation. 
     In various embodiments, wound dressing  100  can be formed as a substantially flat sheet for topical application to wounds or contoured for application to body surfaces having high curvature. The size of wound dressing  100  can vary depending on the size of the wound to be dressed. For example, it is contemplated that the size of wound dressing  100  can range from 1 cm 2  to 200 cm 2 , and more preferably from 4 cm 2  to 100 cm 2 . However, other shapes and sizes of wound dressing  100  are also possible depending on the intended use. 
     Backing Layer 
     Backing layer  102  is shown to include a first side  112  and a second, wound-facing side  114  opposite first side  112 . When wound dressing  100  is applied to a wound, first side  112  faces away from the wound whereas second side  114  faces toward the wound. Backing layer  102  supports elastic film  104 , absorbent layer  106 , and non-adherent layer  108  and provides a barrier to passage of microorganisms through wound dressing  100 . In some embodiments, backing layer  102  is a thin layer of polyurethane film. One example of a suitable material for backing layer  102  is the polyurethane film known as ESTANE 5714F. Other suitable polymers for forming backing layer  102  include poly alkoxyalkyl acrylates and methacrylates, such as those described in Great Britain Patent Application No. 1280631A filed Nov. 22, 2002, the entire disclosure of which is incorporated by reference herein. In some embodiments, backing layer  102  includes a continuous layer of a high-density blocked polyurethane foam that is predominantly closed-cell. Backing layer  102  may have a thickness in the range of 10 μm to 100 μm, preferably in the range of 50 μm to 70 μm. In some embodiments, backing layer  102  has a thickness of approximately 60 μm. 
     In some embodiments, backing layer  102  provides a barrier to microbes, a barrier to external contamination, and protection from physical trauma. For example, backing layer  102  may be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or two environments, such as between a therapeutic environment and a local external environment. Backing layer  102  may be formed of a suitable material, such as a polymer, for example, which may include an elastomeric film or membrane that can provide a seal at a tissue site. In some embodiments, backing layer  102  has a high moisture-vapor transmission rate (MVTR). For example, the MVTR of backing layer  102  may be at least 300 g/m 2  per twenty-four hours. 
     Backing layer  102  may be substantially impermeable to liquid and substantially permeable to moisture vapor. In other words, backing layer  102  may be permeable to water vapor, but not permeable to liquid water or wound exudate. This increases the total fluid handling capacity (TFHC) of wound dressing  100  while promoting a moist wound environment. In some embodiments, backing layer  102  is also impermeable to bacteria and other microorganisms. In some embodiments, backing layer  102  is configured to wick moisture from dressing layer  105  and distribute the moisture across first side  112 . 
     Side  114  of backing layer  102  may be coated with an acrylic or other adhesive. The adhesive applied to side  114  ensures that wound dressing  100  adheres to surface  130  and that wound dressing  100  remains in place throughout the wear time. In some embodiments, the perimeter of backing layer  102  extends beyond (e.g., circumscribes) the perimeters of dressing layer  105  (i.e., elastic film  104  and absorbent layer  106 ) and non-adherent layer  108  to provide an adhesive-coated margin for adhering wound dressing  100  to the skin of a patient adjacent to the wound being treated, shown in  FIG. 1  as surface  130 . The adhesive-coated margin may extend around all sides of dressing layer  105  and non-adherent layer  108  such that wound dressing  100  is a so-called island dressing. In other embodiments, the adhesive-coated margin can be eliminated and wound dressing  100  can be adhered to surface  130  using other techniques. 
     In some embodiments, side  114  of backing layer  102  contacts side  116  of elastic film  104 . Side  114  of backing layer  102  may be adhered to side  116  of elastic film  104  or may simply contact side  116  without the use of an adhesive. In some embodiments, the perimeter of non-adherent layer  108  extends beyond (i.e., circumscribes) the perimeter of dressing layer  105  to provide a margin around the perimeter of dressing layer  105 . Side  114  of backing layer  102  may extend beyond the perimeter of dressing layer  105  to contact side  124  of non-adherent layer  108 . Side  114  of backing layer  102  may adhere to side  124  of non-adherent layer  108  along the margin that extends beyond dressing layer  105 . In this way, backing layer  102  and non-adherent layer  108  may form a closed pocket, sealing dressing layer  105  between backing layer  102  and non-adherent layer  108 . 
     In some embodiments, the adhesive applied to side  114  of backing layer  102  is moisture vapor transmitting and/or patterned to allow passage of water vapor therethrough. The adhesive may include a continuous moisture vapor transmitting, pressure-sensitive adhesive layer of the type, conventionally used for island-type wound dressings (e.g., a polyurethane-based pressure sensitive adhesive). One example of an adhesive which can be used is a pressure sensitive adhesive based on acrylate ester copolymers, polyvinyl ethyl ether and polyurethane, as described in Great Britain Patent Application No.  1280631 A. The basis weight of the adhesive may be 20 to 250 g/m 2 , and more preferably 50 to 1.50 g/m 2 . 
     Elastic Film 
     Elastic film  104  is shown to include a first side  116  and a second, wound-facing side  118  opposite first side  116 . When wound dressing  100  is applied to a wound, first side  116  faces away from the wound whereas second side  118  faces toward the wound. Side  116  can be configured to contact side  114  of backing layer  102 , whereas side  118  can be configured to contact side  120  of absorbent layer  106 . Elastic film  104  is configured to elastically deform upon application of a stretching force to wound dressing  100 . For example, elastic film  104  can elastically stretch when the stretching force is applied and can elastically recover when the stretching force is removed. In other words, elastic film  104  is configured to exhibit substantially elastic deformation and recovery. 
     In this context, a material that exhibits substantially elastic recovery under tissue treatment conditions is termed “elastic,” whereas a material that does not exhibit substantially elastic recovery under tissue treatment conditions is termed “inelastic” or “not elastic.” In some embodiments, wound dressing  100  or any layer(s) thereof, having a width and a length perpendicular to the width, may be considered elastic if it exhibits at most about 10% (advantageously about 5% or less or about 2% or less) permanent deformation (i.e., plastic deformation) when subjected to about 50% strain, relative to the length, for about 3 days at that strain level. In some embodiments, wound dressing  100  or any layer(s) thereof may be considered elastic if it exhibits at most about 5%, advantageously about 2% or less or about 1 or less, permanent deformation when subjected to about 25% strain, relative to the length, for about 24 hours at that strain level. In some embodiments, wound dressing  100  or any layer(s) thereof may be considered elastic if it exhibits at most about 1% (advantageously about 0%) permanent deformation when subjected to about 10% strain, relative to the length, for about 10 minutes at that strain level. 
     Even though particular values are specified with respect to the strain test, materials, layers, or compositions may be considered elastic if optionally tested with one or more parametric deviations. Such parametric deviations may include conducting the strain test at a greater strain than specified (e.g., between about 50% strain and about 100% strain, between about 25% strain and about 75% strain, or between about 10% strain and about 50% strain), conducting the strain test for a longer time than specified (e.g., between about 10 minutes and about 120 hours, between about 24 hours and about 96 hours, or between about 3 days and about 7 days), and/or conducting the strain test at a greater strain rate (e.g., between about 1% elongation per minute and about 600% elongation per minute, between about 10% elongation per minute and about 1200% elongation per minute, or between about 1% elongation per second and about 40% elongation per second). 
     Elastic film  104  may be a thin elastic film made of any of a variety of elastic materials. For example, elastic film  104  may be a polyurethane film, a polyethylene film, or other thin elastic film. In some embodiments, elastic film  104  has a thickness between 20 μm and 50 μm. In some embodiments, elastic film  104  has a thickness of approximately 30 μm. It is contemplated that the thickness of elastic film can vary based on the elasticity and/or strength of the material used to form elastic film  104 . For example, elastic film  104  may be relatively thinner when the material used to form elastic film  104  has a high elasticity and/or strength, whereas elastic film  104  may be relatively thicker if the material used to form elastic film  104  has a lower elasticity and/or strength. The thickness of elastic film  104  can be selected to achieve a desired amount of force required to stretch elastic film  104 . 
     In some embodiments, elastic film  101  is fenestrated in one or more directions to reduce the amount of force required to stretch elastic film  104 . Several examples of fenestration patterns which can be used with elastic film  104  are described in greater detail with reference to  FIGS. 8A-11B . In some embodiments, elastic film  104  is substantially impermeable to liquid and substantially permeable to moisture vapor. In other words, elastic film  104  may be permeable to water vapor, but not permeable to liquid water or wound exudate. Elastic film  104  can be configured to transmit water vapor at any of a variety of transmission rates based on the desired breathability and/or moisture vapor transmission rate (MVTR) for wound dressing  100 . 
     Absorbent Layer 
     Absorbent layer  106  is configured to absorb wound fluid. Absorbent layer  106  is shown to include a first side  120  and a second, wound-facing side  122  opposite first side  120 . When wound dressing  100  is applied to a wound, first side  120  faces away from the wound whereas second side  120  faces toward the wound. Side  120  can be configured to contact side  118  of elastic film  104 , whereas side  122  can be configured to contact side  124  of non-adherent layer  108 . For embodiments in which non-adherent layer  108  is omitted, side  122  of absorbent layer  106  can be configured to contact the wound directly. 
     Absorbent layer  106  may be made of a material that is inelastic (i.e., does not exhibit elastic deformation and recovery). For example, absorbent layer  106  may plastically deform when a stretching force is applied. However, absorbent layer  106  may not substantially recover or return to its original size or shape when the stretching force is removed. For purposes of this disclosure, a material may be considered “inelastic” if it deforms when a stretching force is applied, but recovers by less than a threshold amount when the stretching force is removed. The threshold amount may be defined as a percentage of the deformation (i.e., the difference between the stretched length and non-stretched length). For example, a perfectly elastic material recovers by 100%, meaning that 100% of the deformation is recovered and the perfectly elastic material returns to its original length. However, an inelastic material may recover by substantially less than 100% such that some or all of the deformation is retained as permanent deformation. For example, an inelastic material may recover less than 50% of the deformation (advantageously less than 25% or less than 10% of the deformation). In some embodiments, an inelastic material recovers less than 5% or less than 2% of the deformation. It should be noted that an inelastic material can recover a portion of the deformation and still be considered inelastic as long as the recovery amount does not exceed the threshold amount (e.g., 50% of the deformation, 25% of the deformation, 10% of the deformation, 5% of the deformation, 2% of the deformation, etc.). Accordingly, inelastic absorbent layer  106  may recover some, but not all, of the deformation when the stretching force is removed. 
     In some embodiments absorbent layer  106  exhibits different elastic properties when dry and wet. For example, absorbent layer  106  may be relatively more inelastic when absorbent layer  106  is wet and relatively less inelastic when absorbent layer  106  is dry. In other words, the amount of deformation that absorbent layer  106  recovers when wet may be less than the amount of deformation that absorbent layer  106  recovers when dry. For purposes of this disclosure, “inelastic absorbent” refers to an absorbent material that is inelastic when wet. The criteria for classifying absorbent layer  106  as inelastic when wet may be the same as previously described. For example, absorbent layer  106  may recover less than 50% of the deformation (advantageously less than 25% or less than 10% of the deformation) when wet. In some embodiments, absorbent layer  106  recovers less than 5% or less than 2% of the deformation when wet. However, absorbent layer  106  may be imbued with elastic properties when welded to elastic film  104 , as described in greater detail below. In some embodiments, absorbent layer  106  includes a nonwoven hydrofiber material. For example, absorbent layer  106  may include comprises an entanglement of nonwoven fibers configured to separate from each other when the stretching force is applied. 
     Absorbent layer  106  may include a nonwoven material of predominantly nonwoven fibers. In some embodiments, absorbent layer  106  includes a combination of gelling (i.e., absorbent) fibers and non-gelling (i.e., reinforcing) fibers. The ratio of gelling fibers to non-gelling fibers can be varied to achieve different levels of force required to stretch absorbent layer  106 . For example, the percentage of non-gelling reinforcing fibers may vary from 0% to 20%. The density and/or entanglement of fibers can be varied to adjust the amount of force required to stretch absorbent layer  106 . In some embodiments, the density and/or entanglement of fibers within absorbent layer  106  is non-uniform such that some areas of absorbent layer  106  stretch more than others when a stretching force is applied to absorbent layer  106 . Absorbent layer  106  may have a range of material weights (e.g., from 100 GSM to 250 GSM). 
     In some embodiments, absorbent layer  106  includes a combination of cellulosic fibers and reinforcing fibers. For example, absorbent layer  106  may include from about 45 parts to about 95 parts by weight of cellulosic fibers (e.g., cellulose ether) and from about 5 parts to about 55 parts by weight of reinforcing fibers. In particular embodiments, absorbent layer  106  may include from about 50 parts to about 95 parts by weight of cellulosic fibers, from about 45 parts to about 90 parts by weight of cellulosic fibers, from about 50 parts to about 90 parts by weight of cellulosic fibers, from about 60 parts to about 90 parts by weight of cellulosic fibers, from about 65 parts to about 85 parts by weight of cellulosic fibers, or from about 70 parts to about 90 parts by weight of cellulosic fibers. The cellulosic fibers may be composed of at least one of carboxymethyl cellulose (CMC), carboxylethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and cellulose ethyl sulphonate (CES) (particularly carboxymethyl cellulose). 
     Absorbent layer  106  may include from about 50 parts to about 5 parts by weight of reinforcing fibers, from about 55 parts to about 10 parts by weight of reinforcing fibers, from about 50 parts to about 10 parts by weight of reinforcing fibers, from about 45 parts to about 10 parts by weight of reinforcing fibers, from about 40 parts to about 10 parts by weight of reinforcing fibers, from about 35 parts to about 15 parts by weight of reinforcing fibers, from about 30 parts to about 10 parts by weight of reinforcing fibers, from about 30 parts to about 15 parts by weight of reinforcing fibers, or from about 25 parts to about 10 parts by weight of reinforcing fibers. The reinforcing fibers may be composed of at least one of non-gelling cellulose, a polyurethane gel, an amide polymer such as Nylon 6,6, an olefin polymer such as HDPE, an ester polymer such as PET, and/or a modified acrylamide polymer. 
     In some optional embodiments, biodegradable components may additionally be present in absorbent layer  106 , for example in amounts from about 1 part to about 20 parts by weight (e.g., such as from about 1 part to about 20 parts by weight, from about 1 part to about 15 parts by weight or from about 1 part to about 10 parts by weight. The biodegradable components may be composed of, but not limited to, an alginic acid, an alginate salt, chitosan, chitin, a guar gum, a locust bean gum, a xanthan gum, a karaya gum, gelatin, pectin, a starch derivative, a glycosaminoglycan, a galactomannan, a chondroitin salt, heparin, a heparin salt, collagen, oxidized regenerated cellulose (ORC), hyaluronic acid, a hyaluronate salt, or a combination thereof. 
     In some embodiments, absorbent layer  106  is a single layer, whereas in other embodiments, absorbent layer  106  may include a multi-layer composite structure. For example, absorbent layer  106  may include at least two layers coupled to each other. Layers of the multi-layer composite structure may be coupled to each other using any appropriate technique. In some embodiments, a lamination process can be used to couple layers together, particularly where neither of the layers to be coupled are fibrous or only one of the two layers is fibrous. In some embodiments, an adhesive can be used to directly or indirectly couple layers together. In such embodiments, direct adhesion can be used particularly where neither of the layers to be coupled are fibrous, and indirect adhesion can be used particularly where at least one of the two layers is fibrous. 
     In some embodiments where at least one of the layers is fibrous, a needling apparatus, such as a needle loom machine, can be used to couple the fibrous layer to the other layer, whether fibrous or porous. Needling apparatuses may be used to knit together different types of fibrous materials, such as nonwoven materials. Typically, in needling apparatuses, a bottom layer can be coupled to a top layer by co-feeding the two layers through the apparatus to be simultaneously needled. By operation of such apparatuses, one or more barbed needles can be punctured into/through the fibrous material(s). Differences in strength or connectivity in coupling can arise in needling treatments from different numbers or arrays of barbed needles, from different barbed needle puncture speeds or frequencies, from different sizes of barbs or needles, from the like, or from some combination thereof. Repeated action of the barbed needles may effectively entangle or interweave the fibers of one or the layers with either the fibers or pore structure of the other layer, resulting in effective coupling. 
     In some embodiments, absorbent layer  106  includes multiple layers coupled by needling. For example, in a first step, coupling can be attained by co-feeding a top layer and a bottom layer through a needling apparatus to form a multi-layer composition. Then, by controlling the depth of needling, the top layer of the multi-layer composite, which represents the lower “layer” in this second step, can be coupled to a (fibrous) upper layer by co-feeding both to the needling apparatus and by ensuring that the needling depth does not exceed the thickness of the top layer of the composite, thereby forming a three-layer composite formed by two couplings via the needling apparatus. This process can be repeated with any desired number of layers to attain more highly layered composites. Additionally or alternatively, it is possible in multi-layered composites having at least two couplings for at least one of the couplings can be accomplished via needling, while at least one of the other couplings can be accomplished via a different coupling method, such as via lamination. 
     In some embodiments, absorbent layer  106  includes an antimicrobial agent or other active agents to promote effective wound healing. Non-limiting examples of such active materials may include antimicrobial silver, silver oxidized regenerated cellulose (ORC) (e.g., approximately 25 wt % ionically bound silver), polyhexamethylene biguanide (PHMB), non-steroidal anti-inflammatory drugs such as acetaminophen, steroids, anti-inflammatory cytokines, anesthetics, antimicrobial agents such as penicillin or streptomycin, antiseptics such as chlorhexidine, growth factors such as a fibroblast growth factor (FGF), a platelet derived growth factor (PDGF), or an epidermal growth factor (EGF), and other therapeutic agents, individually or in any combination. If present, such active materials may typically be included at any effective level that show therapeutic efficacy, while preferably not being at such a high level as to significantly counteract any critical or desired physical, chemical, or biological property of the dressing. Depending upon the therapeutic goal, any active material may be loaded at a level of from about 10 wppm to about 10 wt % of the layer in which it is present, for example, from about 50 wppm to about 5 wt % or from about 100 wppm to about 1 wt %. 
     Welds 
     Wound dressing  100  is shown to include a plurality of welds  110  that fix elastic film  104  to absorbent layer  106 . In some embodiments, welds  110  fix side  118  of elastic film  104  to side  120  of absorbent layer  106 . In various embodiments, welds  110  may be limited to the plane of contact between elastic film  104  and absorbent layer  106 , or may extend into at least one of elastic film  104  and/or absorbent layer  106 . For example,  FIG. 2  shows welds  110  extending entirely through elastic film  104  and absorbent layer  106  (i.e., from side  116  of elastic film  104  to side  122  of absorbent layer  106 ). In some embodiments, welds  110  are radio frequency (RF) welds. However, it is contemplated that other types of welds  110  can also be used to fix elastic film  104  to absorbent layer  106 . 
     Advantageously, welds  110  fix elastic film  104  to absorbent layer  106  such that elastic film  104  and absorbent layer  106  elastically deform (i.e., elastically stretch and elastically recover) as a unit. In some embodiments, the plurality of welds  110  are distributed uniformly across elastic film  104  and absorbent layer  106  (e.g., in a grid) to fix elastic film  104  to absorbent layer  106  at multiple locations evenly spaced across wound dressing  100 . A uniform distribution of welds  110  may cause wound dressing  100  to elastically stretch and elastically recover uniformly (e.g., all parts of wound dressing  100  stretch substantially equally). In other embodiments, welds  110  can be distributed non-uniformly across wound dressing  100 . A non-uniform distribution of welds  110  may cause wound dressing  100  to elastically stretch and elastically recover non-uniformly (e.g., some parts of wound dressing  100  stretch more than others). 
     Welds  110  can have any of a variety of shapes or sizes. For example, in some embodiments, welds  110  are spot welds having diameters between 2 mm and 3 mm. In other embodiments, welds  110  are bar welds, half-moons, or arcs spaced across elastic film  104  and absorbent layer  106 . The size, shape, angle, and/or positioning of welds  110  can be selected to optimize strain distribution and achieve a desired ease or resistance of the expansion and collapse of elastic film  104  and absorbent layer  106 . For example, the spacing between welds  110  can be increased in the central region of wound dressing  100  to cause wound dressing  100  to exhibit less strain in the central region. The spacing of welds  110  can be staggered such that an open area or rows between welds  110  in the central region of wound dressing is located between non-aligned welds  110 . This may result in a higher required force to stretch the central region of wound dressing  100 , which may be desirable for applications in which wound dressing  100  is placed over a wound on a highly flexible portion of a patient&#39;s body (e.g., knee, elbow, shoulder, etc.). In some embodiments, welds  110  can be arranged to form lettering or other symbols on wound dressing  100  (e.g., branding, directional instructions, etc.). 
     Advantageously, welds  110  secure elastic film  104  to absorbent layer  106  such that the elastic properties of elastic film  104  are imbued to absorbent layer  106 . For example, when a stretching force is applied to wound dressing  100 , both elastic film  104  and absorbent layer  106  may stretch together, as a unit. When the stretching force is removed, elastic film  104  may elastically recover and return to its original shape. Because elastic film  104  is secured to absorbent layer  106 , elastic film  104  may apply an elastic recovery force to absorbent layer  106  via the plurality of welds  110  when returning to its original shape. The elastic recovery force causes absorbent layer  106  to elastically recover along with elastic film  104 . 
     Non-Adherent Layer 
     In some embodiments, wound dressing  100  includes a non-adherent layer  108 . Non-adherent layer  108  is shown to include a first side  124  and a second, wound-facing side  126  opposite first side  124 . When wound dressing  100  is applied to a wound, first side  124  faces away from the wound whereas second side  126  faces toward the wound. Side  124  can be configured to contact side  122  of absorbent layer  106 , whereas side  126  can be configured to contact the wound or tissue site over which wound dressing  100  is applied. Accordingly, non-adherent layer  108  may function as a contact layer providing an interface between wound dressing  100  and the wound or tissue site. 
     Non-adherent layer  108  may be advantageous in fibrinous situations to reduce potential adherence of absorbent layer  106  to the wound or tissue site, to enable fluid to be effectively drawn away from the wound via non-adherent layer  108 , absorbent layer  106 , or both. In some embodiments, non-adherent layer  108  is made of a hydrophobic material such as polyethylene (PE) or other hydrophobic polymers. The use of a hydrophobic material for non-adherent layer  108  may be particularly advantageous to prevent the attachment of bacteria to the wound or tissue site. In some embodiments, non-adherent layer  108  is perforated for increased fluid flow. 
     In various embodiments, non-adherent layer  108  may include at least one of an alkyl acrylate polymer (e.g., a methyl acrylate polymer, an ethyl acrylate polymer, or the like) an alkacrylate polymer (e.g., a methacrylate polymer, an ethacrylate polymer, or the like) and/or an alkyl alkacrylate polymer (e.g., a methyl methacrylate polymer, an ethyl methacrylate polymer, a methyl ethacrylate polymer, an ethyl ethacrylate polymer, or the like). Such (alk)acrylate polymers may be homopolymers but are more often copolymers, for example, with olefin comonomers. In some embodiments, non-adherent layer  108  includes anethylene-methyl acrylate copolymer, such as used in TIELLE dressings and SILVERCEL non-adherent dressings available from Systagenix Wound Management, Limited. In various embodiments, non-adherent layer  108  may include a silicone or polysiloxane polymer or copolymer. 
     In some embodiments, the perimeter of non-adherent layer  108  extends beyond the perimeter of dressing layer  105  such that a portion of non-adherent layer  108  contacts the wound-facing side  114  of backing layer  102 . The perimeter of non-adherent layer  108  may contact the adhesive-coated margin of backing layer  102  to allow the perimeter of non-adherent layer  108  to adhere directly to backing layer  102 , thereby forming a closed pocket within which dressing layer  105  is contained. In some embodiments, non-adherent layer  108  includes perforations through which backing layer  102  can contact surface  130  surrounding the wound. Alternatively, backing layer  102  may extend beyond a perimeter of non-adherent layer  108  to adhere to surface  130  around the outer perimeter of non-adherent layer  108 . 
     Dressing Layer 
     Referring now to  FIGS. 3-7 , dressing layer  105  is shown, according to an exemplary embodiment.  FIG. 3  is a top plan view of dressing layer  105 , whereas  FIG. 4  is a top perspective view of dressing layer  105 . As described above, dressing layer  105  may include elastic film  104 , absorbent layer  106 , and a plurality of welds  110  that fix elastic film  104  to absorbent layer  106 . In some embodiments, dressing layer  105  also includes non-adherent layer  108  coupled to the wound-facing side  122  of absorbent layer  106 . As shown in  FIG. 3 , elastic film  104  and non-adherent layer  108  may encapsulate absorbent layer  106 . For example, the perimeters of elastic film  104  and non-adherent layer  108  may be sealed together or adhered to each other to form a closed container within which absorbent layer  106  is located. 
     In some embodiments, dressing layer  105  is formed by pre-stretching elastic film  104  (as shown in  FIG. 5 ) and welding the pre-stretched elastic film  104  to absorbent layer  106  (as shown in  FIG. 6 ). The amount elastic film  104  is pre-stretched may depend on the elastic requirements of dressing layer  105  and the limitations of the materials used. In various embodiments, elastic film  104  can be stretched by an amount ranging from 5% to 40% of its original length, 15% to 30% of its original length, 20% to 25% of its original length, or preferably by approximately 20% of its original length prior to welding elastic film  104  to absorbent layer  106 . 
     After welds  110  are added to secure the pre-stretched elastic film  104  to absorbent layer  106 , the stretching force can be removed. In the absence of the stretching force, elastic film  104  may elastically recover, returning substantially to its original length. This causes absorbent layer  106  to compress (i.e., bunch up, collapse, etc.) longitudinally (as shown in  FIG. 7 ), forming a plurality of waves or ridges  134  along the surface of absorbent layer  106 . As an alternative to pre-stretching elastic film  104 , absorbent layer  106  can be pre-compressed prior to adding welds  110 . The resultant dressing layer  105  may be substantially the same as produced by the pre-stretching approach (i.e., absorbent layer  106  in a compressed state). 
     If a stretching force is subsequently applied to dressing layer  105 , absorbent layer  106  can expand longitudinally (i.e., using the slack provided by ridges  134 ) without providing any resistance to stretching. The only resistance to stretching may come from elastic film  104 , at least until absorbent layer  106  has completely flattened. Advantageously, this allows dressing layer  105  to be stretched by an amount equal to the pre-stretching of elastic film  104  (e.g., approximately 20%) with a relatively low stretching force (e.g., less than 2 N) since only elastic film  104  is providing resistance to stretching within the initial pre-stretching range. This also helps prevent the non-woven fibers of absorbent layer  106  from separating from each other since any stretching of absorbent layer  106  that occurs within the initial pre-stretching range is achieved by flattening ridges  134  rather than pulling apart the fibers of absorbent layer  106 . 
     In some embodiments, elastic film  104  is welded to absorbent layer  106  without pre-stretching elastic film  104  and/or without pre-compressing absorbent layer  106 . The welded assembly (i.e., dressing layer  105 ) can be stretched after the welding is complete. Such stretching may occur while wound dressing  100  is in use and/or during further fabrication of wound dressing  100 . For example, dressing layer  105 , as a whole, can be pre-stretched before dressing layer  105  is combined with backing layer  102  and/or non-adherent layer  108  to form wound dressing  100 . The resultant wound dressing  100  may exhibit many of the same properties and advantages that result from pre-stretching elastic film  104 , as previously described. 
     Fenestrations 
     Referring now to  FIGS. 8A-11B , several patterns of welds  110  and fenestrations  132  which can be applied to wound dressing  100  are shown, according to various exemplary embodiments. Fenestrations  132  may be small cuts (e.g., slits, apertures, etc.) in one or more layers of wound dressing  100 . In some embodiments, each of fenestrations  132  has a length of approximately 2 mm to 3 mm and a width of approximately 0.5 mm. However, other sizes and shapes of fenestrations  132  can be used in alternative embodiments. In various embodiments, fenestrations  132  can be added to absorbent layer  106 , elastic film  104 , non-adherent layer  108 , and/or any combination thereof. Fenestrations  132  can be configured to increase the distance that wound dressing  100  stretches per unit of stretching force applied. In other words, fenestrations  132  may decrease the resistance to stretching provided by wound dressing  100 . 
     The orientation of fenestrations  132  may imbue wound dressing  100  with varying levels of stretching resistance along different dimensions (e.g., length, width, etc.) based on the alignment of fenestrations  132  with the dimensions of wound dressing  100 . In some embodiments, fenestrations  132  are substantially linear and oriented directionally such that fenestrations  132  reduce stretching resistance along only a single dimension of wound dressing  100 . For example, wound dressing  100  may have a length (L) defining a size of wound dressing  100  along a first dimension (e.g., up and down in  FIGS. 8A-11B ) and a width (W) defining a size of wound dressing along a second dimension substantially perpendicular to the first dimension (e.g., left and right in  FIGS. 8A-11B ). In some embodiments, the width (W) is less than the length (L). Fenestrations  132  can be aligned with the width dimension or the length dimension to reduce the stretching resistance of wound dressing along either the width dimension or the length dimension. 
       FIGS. 8A-8B  illustrate an embodiment in which wound dressing  100  includes several rows of substantially linear fenestrations  132  aligned with the width (W) dimension of wound dressing  100 . Each row of fenestrations  132  may include multiple fenestrations  132  arranged substantially linearly. Fenestrations  132  aligned with the width (W) dimension of wound dressing  100  may increase the distance that wound dressing  100  stretches along the length (L) dimension per unit of stretching force applied along the length (L) dimension. In other words, fenestrations  132  aligned with the width (W) dimension of wound dressing  100  may reduce the stretching resistance of wound dressing  100  along the length (L) dimension. 
     The embodiment shown in  FIGS. 8A-8B  also includes a substantially rectangular grid of welds  110  spaced uniformly along wound dressing  100 . In some embodiments, the rows of linear fenestrations  132  are located between rows of welds  110 . For example, rows of welds  110  and rows of fenestrations  132  may be arranged in an alternating pattern along the length (L) of wound dressing  100 . In some embodiments, fenestrations  132  are spaced uniformly between welds  110 . In other embodiments, fenestrations  132  may be spaced non-uniformly. A non-uniform spacing of fenestrations  132  can be used to achieve different levels of stretching resistance at different portions of wound dressing  100 . For example, a region of wound dressing  100  with few fenestrations  132  may have a relatively high stretching resistance, whereas a region of wound dressing  100  with more fenestrations  132  may have a relatively lower stretching resistance. 
       FIGS. 9A-9B  illustrate an embodiment in which wound dressing  100  includes several columns of substantially linear fenestrations  132  aligned with the length (L) dimension of wound dressing  100 . Each column of fenestrations  132  may include multiple fenestrations  132  arranged substantially linearly. Fenestrations  132  aligned with the length (L) dimension of wound dressing  100  may increase the distance that wound dressing  100  stretches along the width (W) dimension per unit of stretching force applied along the width (W) dimension. In other words, fenestrations  132  aligned with the length (L) dimension of wound dressing  100  may reduce the stretching resistance of wound dressing  100  along the width (W) dimension. 
     The embodiment shown in  FIGS. 9A-9B  also includes a substantially rectangular grid of welds  110  spaced uniformly along wound dressing  100 . In some embodiments, the rows of linear fenestrations  132  are located between rows of welds  110 . For example, rows of welds  110  and rows of fenestrations  132  may be arranged in an alternating pattern along the width (W) of wound dressing  100 . As with the embodiment shown in  FIGS. 8A-8B , fenestrations  132  can be spaced uniformly or non-uniformly between welds  110 . 
       FIGS. 10A-10B  illustrate another embodiment in which wound dressing  100  includes several rows of substantially linear fenestrations  132  aligned with the width (W) dimension of wound dressing  100 , but does not include any welds  110 . Each row of fenestrations  132  may include multiple fenestrations  132  arranged substantially linearly. Fenestrations  132  aligned with the width (W) dimension of wound dressing  100  may increase the distance that wound dressing  100  stretches along the length (L) dimension per unit of stretching force applied along the length (L) dimension. In other words, fenestrations  132  aligned with the width (W) dimension of wound dressing  100  may reduce the stretching resistance of wound dressing  100  along the length (L) dimension. Fenestrations  132  can be spaced uniformly or non-uniformly, as previously described. 
       FIGS. 11A-11B  illustrate an embodiment in which wound dressing  100  includes several columns of substantially linear fenestrations  132  aligned with the length (L) dimension of wound dressing  100 , but does not include any welds  110 . Each column of fenestrations  132  may include multiple fenestrations  132  arranged substantially linearly. Fenestrations  132  aligned with the length (L) dimension of wound dressing  100  may increase the distance that wound dressing  100  stretches along the width (W) dimension per unit of stretching force applied along the width (W) dimension. In other words, fenestrations  132  aligned with the length (L) dimension of wound dressing  100  may reduce the stretching resistance of wound dressing  100  along the width (W) dimension. Fenestrations  132  can be spaced uniformly or non-uniformly, as previously described. 
     Configuration of Exemplary Embodiments 
     The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements can be reversed or otherwise varied and the nature or number of discrete elements or positions can be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps can be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.