Patent Publication Number: US-2013232761-A1

Title: Method of Manufacturing a Dressing for an Insertion Site of an Intravascular Infusate

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of U.S. Provisional Application No. 61/609,865, filed 12 Mar. 2012, which is hereby incorporated by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
       FIG. 10  shows a typical arrangement for intravascular infusion. The term intravascular preferably refers to being situated in, occurring in, or being administered by entry into a blood vessel, thus “intravascular infusion” preferably refers to introducing a fluid into a blood vessel. Intravascular infusion accordingly encompasses both intravenous infusion (administering a fluid into a vein) and intra-arterial infusion (administering a fluid into an artery). 
     A cannula  20  is typically used for administering fluid via a subcutaneous blood vessel. Typically, cannula  20  is inserted through epidermis E at an insertion site S and punctures, for example, the cephalic vein, basilica vein, median cubital vein, or any suitable vein for an intravenous infusion. Similarly, any suitable artery may be used for an intra-arterial infusion. 
     Cannula  20  typically is in fluid communication with a fluid source  22 . Typically, cannula  20  includes a hub  20   a  or another extracorporeal connector and fluid source  22  includes one or more sterile containers that hold the fluid(s) to be administered. Examples of typical sterile containers include plastic bags, glass bottles or plastic bottles. 
     An administration set  30  typically provides a sterile conduit for fluid to flow from fluid source  22  to cannula  20 . Typically, administration set  30  includes tubing  32 , a drip chamber  34 , a flow control device  36 , and a cannula connector  38 . Tubing  32  is typically made of polypropylene, nylon, or another flexible, strong and inert material. Drip chamber  34  typically permits the fluid to flow one drop at a time for reducing air bubbles in the flow. Tubing  32  and drip chamber  34  are typically transparent or translucent to provide a visual indication of the flow. Typically, flow control device  36  is positioned upstream from drip chamber  34  for controlling fluid flow in tubing  34 . Roller clamps and Dial-A-Flo®, manufactured by Hospira, Inc. (Lake Forest, Ill., USA), are examples of typical flow control devices. Typically, cannula connector  38  and hub  20   a  provide a leak-proof coupling through which the fluid may flow. Luer-Lok™, manufactured by Becton, Dickinson and Company (Franklin Lakes, N.J., USA), is an example of a typical leak-proof coupling. 
     Administration set  30  may also include at least one of a clamp  40 , an injection port  42 , a filter  44 , or other devices. Typically, clamp  40  pinches tubing  34  to cut-off fluid flow. Injection port  42  typically provides an access port for administering medicine or another fluid via cannula  20 . Filter  44  typically purifies and/or treats the fluid flowing through administration set  30 . For example, filter  44  may strain contaminants from the fluid. 
     An infusion pump  50  may be coupled with administration set  30  for controlling the quantity or the rate of fluid flow to cannula  20 . The Alaris® System manufactured by CareFusion Corporation (San Diego, Calif., USA) and Flo-Gard® Volumetric Infusion Pumps manufactured by Baxter International Inc. (Deerfield, Ill., USA) are examples of typical infusion pumps. 
     Unintended infusing typically occurs when fluid from cannula  20  escapes from its intended vein/artery. Typically, unintended infusing causes an abnormal amount of a substance to diffuse or accumulate in perivascular tissue or cells and may occur, for example, when (i) cannula  20  causes a brittle vein/artery to rupture; (ii) cannula  20  improperly punctures the vein/artery; (iii) cannula  20  is improperly sized; or (iv) infusion pump  50  administers fluid at an excessive flow rate. Unintended infusing of a non-vesicant fluid is typically referred to as “infiltration,” whereas unintended infusing of a vesicant fluid is typically referred to as “extravasation.” 
     The symptoms of infiltration or extravasation typically include blanching or discoloration of the epidermis E, edema, pain, or numbness. The consequences of infiltration or extravasation typically include skin reactions such as blisters, nerve compression, acute limb compartment syndrome, or necrosis. Typical care for infiltration or extravasation includes applying warm compresses, administering hyaluronidase or phentolamine, fasciotomy, or amputation. 
     BRIEF SUMMARY OF THE INVENTION 
     Embodiments according to the present invention include a method of manufacturing a dressing for an insertion site of an intravascular infusion. The method includes forming a fitting and coupling the fitting and a frame. The fitting has (i) a first arrangement configured to retain a near-infrared sensor for monitoring the intravascular infusion and (ii) a second arrangement configured to release the near-infrared sensor from the first arrangement. The frame has a lower resistance to deformation than the fitting. The fitting is configured to overlay a first area of an epidermis in the first arrangement, the frame is configured to overlay a second area of an epidermis in the first arrangement, and the second area is larger than the first area. 
     Other embodiments according to the present invention include a method of manufacturing a dressing for an insertion site of an intravascular infusion. The method includes molding a frame and coupling a pane to the frame. The frame includes first and second portions. The first portion has a first arrangement configured to retain an electromagnetic spectrum sensor for monitoring the intravascular infusion and a second arrangement configured to release the electromagnetic spectrum sensor from the first arrangement. The pane is configured to overlie the insertion site, and the second portion of the frame cinctures at least a portion of the pane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features, principles, and methods of the invention. 
         FIG. 1  is a schematic view illustrating an embodiment of a dressing according to the present disclosure. 
         FIG. 2  is a partially exploded schematic cross-section view of the dressing shown in  FIG. 1 . 
         FIGS. 3A-3D  illustrate a fitting of the dressing shown in  FIG. 1 .  FIG. 3A  is a plan view,  FIG. 3B  is a cross-section view taken along line IIIB-IIIB in  FIG. 3A ,  FIG. 3C  is an enlarged view illustrating detail IIIC in  FIG. 3B , and  FIG. 3D  is an enlarged view illustrating detail  111 D in  FIG. 3B . 
         FIG. 4  is a schematic view illustrating an embodiment of a dressing according to the present disclosure. 
         FIGS. 5A-5D  are schematic views illustrating details of the dressing shown in  FIG. 4 . 
         FIG. 5A  is a cross-section view taken along line VA-VA in  FIG. 4  with an electromagnetic spectrum sensor shown in dash-dot line,  FIG. 5B  is a detail view showing features of the electromagnetic spectrum sensor in  FIG. 5A ,  FIG. 5C  is a cross-section view taken along line VC-VC in  FIG. 4 , and  FIG. 5D  is a cross-section view taken along line VD-VD in  FIG. 4 . 
         FIGS. 6A and 6B  are schematic views illustrating alternate dressings of an embodiment according to the present disclosure. 
         FIGS. 7A-7D  illustrate an embodiment of a dressing according to the present disclosure.  FIG. 7A  is a schematic plan view showing an assembly including a contamination barrier and a frame,  FIG. 7B  is a schematic plan view showing the contamination barrier prior to assembly,  FIG. 7C  is a schematic plan view showing the frame and a lead management system prior to assembly, and  FIG. 7D  is a schematic plan view showing an implementation of an assembly including the contamination barrier, the frame, and the lead management system. 
         FIGS. 8A-8D  illustrate alternate dressings of an embodiment according to the present disclosure.  FIG. 8A  is a schematic plan view illustrating a dressing including a fitting integrally molded with a frame,  FIG. 8B  is a cross-section view taken along line VIIIB-VIIIB in  FIG. 8A ,  FIG. 8C  is a schematic plan view illustrating a dressing including a fitting over-molded with a frame, and  FIG. 8D  is a cross-section view taken along line VIIID-VIIID in  FIG. 8C . 
         FIG. 9  is a schematic view illustrating an embodiment of a dressing according to the present disclosure. 
         FIG. 10  is a schematic view illustrating a typical set-up for infusion administration. 
     
    
    
     In the figures, the thickness and configuration of components may be exaggerated for clarity. The same reference numerals in different figures represent the same component. The broken lines in the figures are for illustrative purposes only and form no part of the claimed invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. 
     Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various features are described which may be included in some embodiments but not other embodiments. 
     The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Certain terms in this specification may be used to provide additional guidance regarding the description of the disclosure. It will be appreciated that a feature may be described more than one-way. 
     Alternative language and synonyms may be used for any one or more of the terms discussed herein. No special significance is to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any exemplified term. 
       FIGS. 1 and 2  show an embodiment of a dressing  100  that includes (i) a contamination barrier overlying the insertion site S; and (ii) a fitting for coupling an electromagnetic spectrum sensor  1000  that senses if fluid is infusing perivascular tissue around cannula  20 . Dressing  100  preferably provides a contamination barrier that is substantially impervious to solids, liquids, microorganisms and/or viruses. Preferably, dressing  100  may be semi-permeable to allow air or vapor to pass, thus permitting the epidermis E to breathe. 
     Electromagnetic spectrum sensor  1000  preferably aids in diagnosing infiltration or extravasation. Preferably, electromagnetic radiation  1002  is emitted via a sensor surface  1000   a  of electromagnetic spectrum sensor  1000  and electromagnetic radiation  1004  is received via sensor surface  1000   a . Emitted electromagnetic radiation  1002  passes through the epidermis E into the perivascular tissue P. Referring to  FIG. 2 , the perivascular tissue P in the vicinity of a blood vessel V preferably includes the cells or interstitial compartments that may become unintentionally infused, e.g., infiltrated or extravasated by fluid from cannula  20 . Received electromagnetic radiation  1004  is at least a portion of emitted electromagnetic radiation  1002  that is reflected, scattered, diffused, or otherwise redirected from the perivascular tissue P through the epidermis E to sensor surface  1000   a.    
     Emitted and received electromagnetic radiations  1002  and  1004  are preferably in the near-infrared portion of the electromagnetic spectrum. The term “near infrared” refers to electromagnetic radiation having wavelengths between approximately 1,400 nanometers and approximately 700 nanometers—proximate the nominal edge of red light in the visible light portion of the electromagnetic spectrum. These wavelengths correspond to a frequency range of approximately 215 terahertz to approximately 430 terahertz. 
     Electromagnetic spectrum sensor  1000  may be coupled to a processor (not shown) via a lead  1010 . Preferably, the processor or another suitable device analyzes changes over time in received electromagnetic radiation  1004  for providing an indication of fluid infusing the perivascular tissue P. According to other embodiments, electromagnetic spectrum sensor  1000  and the processor may be coupled wirelessly rather than via lead  1010 , or electromagnetic spectrum sensor  1000  may incorporate the processor. 
     Dressing  100  preferably includes a pane  110  for viewing the insertion site S. Preferably, pane  110  is transparent or translucent to light in the visible portion of the electromagnetic spectrum, for example, light having wavelengths between approximately 380 nanometers and approximately 760 nanometers. These wavelengths correspond to a frequency range of approximately 400 terahertz to approximately 790 terahertz. Pane  110  preferably includes polyurethane film or another suitable material and/or construction for providing a contamination barrier that may be transparent or translucent. 
     An adhesive  112  preferably bonds pane  110  to the epidermis E around the insertion site S. Preferably, adhesive  112  includes an acrylic adhesive that is suitable for contact with the epidermis E or another medical grade adhesive that is biocompatible according to Standard 10993 promulgated by the International Organization for Standardization (ISO 10993) and/or Class VI promulgated by The United States Pharmacopeial Convention (USP Class VI). Adhesive  112  may be applied to pane  110  on the entire surface that confronts the epidermis E, or adhesive  112  may be omitted from one or more portions of the surface. Also, the strength of the bond between pane  110  and the epidermis E may vary according to different embodiments of dressing  100 . For example, stronger or more adhesive  112  may be used for coupling dressing  100  to relatively robust skin, e.g., adult skin, and weaker or less adhesive  112  may be used for coupling dressing  100  to relatively delicate skin, e.g., pediatric skin. 
     Pane  110  may also include a diagnostic tool  114  to assist in visually analyzing symptoms of infiltration or extravasation. For example, diagnostic tool  114  may include a set of concentric arcs, a geometric shape, a set of parallel lines, a color gradient, or another suitable reticle for evaluating conditions at the epidermis E that may be symptomatic of infiltration or extravasation. According to one embodiment, the appearance of a set of concentric arcs or a geometric shape may become distorted when the epidermis E, and thus pane  110 , is distended due to edema. According to another embodiment, changes in the coloration of the epidermis E may be evaluated by periodic comparison with a color gradient included on pane  110 . 
     Dressing  100  is preferably located or oriented with respect to at least one of cannula  20 , the insertion site S, or an anatomical feature. According to one embodiment, dressing  100  may include a notch  116   a  or another suitable guide that is sized or shaped for cooperating with at least a portion of cannula  20 . According to another embodiment, pane  110  may include crosshairs  116   b  or another suitable guide for locating dressing  100  relative to the insertion site S. According to another embodiment, indicia, symbols, and/or other markings may provide a guide for relatively orienting dressing  100  with resect to an anatomical feature. For example, guide  116   c  includes an arrow and a symbol that suggests orienting dressing  100  upstream from the heart. 
     Dressing  100  preferably includes a frame  120  coupled to pane  110 . Frame  120  preferably has greater resistance to deformation than does pane  110 . Accordingly, frame  120  may maintain the general shape of pane  110  while dressing  100  is laid over the insertion site S. According to one embodiment, frame  120  entirely cinctures pane  110 . According to other embodiments, frame  120  may (i) partially cincture pane  110 ; (ii) extend from a peripheral portion of pane  110  toward an interior portion of pane  110 ; (iii) extend from the interior portion toward the peripheral portion; (iv) be spaced from the peripheral portion; or (v) include a combination of (i)-(iv). Frame  120  preferably includes polyvinyl chloride, polyethylene, polypropylene, or another suitable material that is relatively rigid with respect to pane  110 . According to one embodiment, frame  120  may include polyethylene tape  120   a  being relatively associated with or disposed on a pad of polyvinyl chloride foam  120   b.    
     Frame  120  is preferably transparent or translucent to visible light for viewing the epidermis E in the vicinity of the insertion site S. Preferably, frame  120  absorbs or blocks the transmission of radiation having the same wavelength as emitted electromagnetic radiation  1002 , e.g., near infrared radiation. Thus, according to one embodiment, the epidermis E that underlies frame  120  may be optically visible and shielded from ambient near-infrared radiation. 
     Frame  120  is preferably coupled to pane  110  by an adhesive  122  or another suitable coupling. According to one embodiment, adhesive  122  preferably provides a coupling between pane  110  and frame  120  that is relatively stronger than the bond between pane  110  and the epidermis E. Accordingly, pane  110  remains attached to frame  120  when separating dressing  100  from the epidermis E. Adhesive  122  according to another embodiment of dressing  100  preferably provides a coupling between pane  110  and frame  120  that is relatively weaker than the bond between pane  110  and the epidermis E. Accordingly, frame  120  may be released from pane  110  after dressing  100  is laid over the insertion site S. 
     Dressing  100  preferably includes a fitting  130  for coupling an anatomic sensor with the epidermis E. As the terminology is used herein, “anatomic” preferably refers to the structure of a body and an “anatomic sensor” preferably is concerned with sensing a change over time of the structure of the body. By comparison, a physiological sensor is concerned with sensing the functions and activities of a body, e.g., pulse, at a point in time. 
     There are preferably two arrangements of fitting  130  with respect to electromagnetic spectrum sensor  1000 . The term “arrangement” as it is used herein preferably refers to a relative configuration, formation, layout or disposition of fitting  130  and electromagnetic spectrum sensor  1000 . A first arrangement of fitting  130  preferably retains electromagnetic spectrum sensor  1000  relative to dressing  100  for monitoring infiltration or extravasation during an infusion with cannula  20 . Accordingly, the first arrangement of fitting  130  with respect to electromagnetic spectrum sensor  1000  preferably senses over time if fluid from cannula  20  is infusing the perivascular tissue P. A second arrangement of fitting  130  preferably releases electromagnetic spectrum sensor  1000  from the first arrangement. The first arrangement preferably includes one or more first surfaces  1006  on electromagnetic spectrum sensor  1000  being snapped under a second surface  132   a  (see  FIGS. 3B and 3C ) on fitting  130 . Accordingly, the second arrangement preferably includes snapping the first surface  1006  over the second surface  132   a  to release electromagnetic spectrum sensor  1000  from the first arrangement. Other embodiments may use a latch, a cap, a resilient element, or another suitable device that, in the first arrangement, retains electromagnetic spectrum sensor  1000  in fitting  130  and preferably biases sensor surface  1000   a  toward the epidermis E and, in the second arrangement, releases electromagnetic spectrum sensor  1000  from fitting  130 , e.g., allowing electromagnetic spectrum sensor  1000  to separate from fitting  130 . Accordingly, the first and second arrangements permit electromagnetic spectrum sensor  1000  to be reused with a plurality of dressings  100  that are individually applied to patients&#39; epidermises. 
     Fitting  130  may be indirectly or directly coupled to pane  110 . According to one embodiment of dressing  100 , frame  120  preferably couples fitting  130  to pane  110 . According to another embodiment of dressing  100 , fitting  130  and pane  110  are preferably directly coupled. Fitting  130  is preferably fixed to dressing  100  using an adhesive  130   a  or another suitable coupling that is relatively stronger than the bond between pane  110  and the epidermis E. Moreover, adhesive  130   a  preferably couples fitting  130  to frame  120  and provides a coupling that is at least as strong as the coupling between frame  120  and pane  110 . 
     Details according to one embodiment of fitting  130  are shown in  FIGS. 3A-3D . Preferably, fitting  130  includes a wall  132  that defines a pocket  134  for receiving electromagnetic spectrum sensor  1000 . In the first arrangement of fitting  130 , wall  132  may (i) entirely surround electromagnetic spectrum sensor  1000 ; (ii) include a plurality of individual segments or posts intermittently disposed around electromagnetic spectrum sensor  1000 ; or (iii) have any suitable configuration for locating electromagnetic spectrum sensor  1000  with respect to dressing  100 . Wall  132  preferably includes one or more second surfaces  132   a —three are shown in FIG.  3 B—that cooperate with first surface(s)  1006  for retaining electromagnetic spectrum sensor  1000  in pocket  134  in the first arrangement of fitting  130 . Preferably, fitting  130  maintains electromagnetic spectrum sensor  1000  in a desired orientation with respect to dressing  100 . According to one embodiment, fitting  130  includes a recess  132   b  that, in the first arrangement, cooperatively receives a projection  1008  (see  FIG. 2 ) on electromagnetic spectrum sensor  1000 . According to other embodiments, fitting  130  and electromagnetic spectrum sensor  1000  may include any suitable mating features for eliminating or at least minimizing rotation of electromagnetic spectrum sensor  1000  in pocket  134 . 
     Fitting  130  and dressing  100  are preferably coupled via an interface that permits dressing  100  to approximately conform to epidermis E. Preferably, a rim or flange  136  projects from wall  134  and provides a surface for adhesive  130   a  at the interface between fitting  130  and dressing  100 . According to one embodiment, flange  136  may include a plurality of segments  136   a -four are shown in  FIG. 3A-separated  by individual gaps  136   b -three are shown in  FIG. 3A . One or more lines of weakness  138  may be disposed on flange  136  to increase flexibility of the interface between fitting  130  and dressing  100 . Accordingly, fitting  130  may approximately conform to the contours of epidermis E to thereby facilitate, in the first arrangement, maintaining and orienting electromagnetic spectrum sensor  1000  relative to insertion site S. 
     Dressing  100  preferably combines in a single unit an occlusive barrier and a retainer for an anatomical sensor. According to one embodiment, the anatomical sensor may include electromagnetic spectrum sensor  1000  or another sensor for sensing over time a change of body structure, e.g., infiltration and extravasation. Preferably, the occlusive barrier includes pane  110  for protecting the insertion site S and the retainer includes fitting  130  for positioning electromagnetic spectrum sensor  1000  to sense if fluid is infusing the perivascular tissue P. Fitting  130  preferably permits electromagnetic spectrum sensor  1000  to be decoupled and recoupled with dressing  100 , or decoupled from a first dressing and coupled to a second dressing. Dressing  100  preferably also includes frame  120  for distributing forces over a larger area of the epidermis E. For example, forces due to pulling or snagging lead  1010  may be distributed by pane  110 , frame  120  and fitting  130  over an area of the epidermis E that is larger than that overlaid by sensor surface  1000   a . Dressing  100  therefore preferably enhances an approximately consistent positional relationship between electromagnetic spectrum sensor  1000  and the perivascular tissue P when sensing infiltration or extravasation. Dressing  100  is advantageous at least because applying an occlusive dressing for an intravascular infusion concurrently establishes an approximately consistent location for an infiltration/extravasation sensor. 
     FIGS.  4  and  5 A- 5 D show an embodiment of a dressing  200  that includes (i) a contamination barrier overlying the insertion site S; and (ii) a plurality of location options for coupling electromagnetic spectrum sensor  1000  to sense if fluid is infusing the perivascular tissue P around cannula  20 . The contamination barrier preferably is substantially impervious to solids, liquids, microorganisms and/or viruses. Preferably, dressing  200  may be semi-permeable to allow air or vapor to pass, thus permitting the epidermis E to breathe. 
     The contamination barrier of dressing  200  preferably includes a pane  210  for viewing the insertion site S. Preferably, pane  210  is transparent or translucent to light in the visible portion of the electromagnetic spectrum. Pane  210  preferably includes a polyurethane film or another suitable material and/or construction for providing a contamination barrier that may be transparent or translucent. 
     An adhesive  212  preferably bonds pane  210  to the epidermis E (not indicated in  FIG. 4 ) around the insertion site S. Preferably, adhesive  212  includes an acrylic adhesive that is suitable for contact with the epidermis E or another medical grade adhesive that is biocompatible according ISO 10993 and/or USP Class VI. Adhesive  212  may be applied to pane  210  on the entire surface that confronts the epidermis E, or adhesive  212  may be omitted from one or more portions of the surface. Also, the strength of the bond between pane  210  and the epidermis E may vary according to different embodiments of dressing  200 . For example, stronger or more adhesive  212  may be used for coupling dressing  200  to relatively robust skin, e.g., adult skin, and weaker or less adhesive  212  may be used for coupling dressing  200  to relatively delicate skin, e.g., pediatric skin. 
     Pane  210  may also include a diagnostic tool  214  to assist in visually analyzing symptoms of infiltration or extravasation. For example, diagnostic tool  214  may include a set of concentric arcs, a geometric shape, a set of parallel lines, a color gradient, or another suitable reticle for evaluating conditions at the epidermis E that may be symptomatic of infiltration or extravasation. According to one embodiment, the appearance of a set of concentric arcs or a geometric shape may become distorted when the epidermis E, and thus pane  210 , is distended due to edema. According to another embodiment, changes in the coloration of the epidermis E may be evaluated by periodic comparison with a color gradient included on pane  210 . 
     Pane  210  may include one or more guides for positioning or orienting dressing  200  on the epidermis E. According to one embodiment, guide  216  preferably includes a notch or some other feature of dressing  200  that may be sized or shaped to receive a portion of cannula  20 . 
     Dressing  200  preferably includes a frame  220  coupled to pane  210 . According to one embodiment of dressing  200 , a coupling between pane  210  and frame  220  is preferably relatively stronger than the bond between pane  210  and the epidermis E. Accordingly, pane  210  remains attached to frame  220  when separating dressing  200  from the epidermis E. 
     Frame  220  preferably has greater resistance to deformation than does pane  210 . Accordingly, frame  220  may maintain the shape of pane  210  while dressing  200  is laid over the insertion site S. According to one embodiment, frame  220  entirely cinctures pane  210 . According to other embodiments, frame  220  may (i) partially cincture pane  210 ; (ii) extend from a peripheral portion of pane  210  toward an interior portion of pane  210 ; (iii) extend from the interior portion toward the peripheral portion; (iv) be spaced from the peripheral portion; or (v) include a combination of (i)-(iv). Frame  220  preferably includes polyvinyl chloride, polyethylene, polypropylene, or another suitable material that is relatively rigid with respect to pane  210 . For example, frame  220  may include a pad of polyvinyl chloride foam. Frame  220  may be opaque, but is preferably transparent or translucent to visible light for viewing the epidermis E in the vicinity of the insertion site S. Preferably, frame  220  absorbs or blocks the transmission of radiation having the same wavelength as emitted electromagnetic radiation  1002 , e.g., near infrared radiation. Thus, according to one embodiment, the epidermis E that underlies frame  220  may be optically visible and shielded from ambient near-infrared radiation. 
     Dressing  200  preferably includes a plurality of fittings to provide alternate location options for coupling with electromagnetic spectrum sensor  1000  to dressing  200 . Preferably, first fitting  230   a  and second fitting  230   b  are disposed at locations on opposite sides of guide  216 . Accordingly, the first arrangements of first and second fittings  230   a  and  230   b  preferably include location options for retaining electromagnetic spectrum sensor  1000  on either side of guide  216  for monitoring infiltration or extravasation during an infusion with cannula  20 . Second arrangements of first fitting  230   a  and second fitting  230   b  preferably release electromagnetic spectrum sensor  1000  from the first arrangements for the respective fittings. 
     Dressing  200  preferably includes multiple fittings to permit multiple options for locating electromagnetic spectrum sensor  1000  relative to the insertion site S. Preferably, electromagnetic spectrum sensor  1000  may be disposed in one of first and second fittings  230   a  and  230   b  with the other of first and second fittings  230   a  and  230   b  may be used for controlling tubing  32  and/or lead  1010 . Permutations of the arrangements of first and second fittings  230   a  and  230   b  with respect to electromagnetic spectrum sensor  1000  may be characterized as “conditions” of dressing  200 . For example, a first condition of dressing  200  may be characterized by the second arrangements of first and second fittings  230   a  and  230   b . Accordingly, electromagnetic spectrum sensor  1000  is not coupled to dressing  200  in the first condition. Electromagnetic spectrum sensor  1000  may be moved from the first condition to a second condition of dressing  200  so as to be in the first arrangement of the first fitting  230   a  and in the second arrangement of second fitting  230   b . Accordingly, electromagnetic spectrum sensor  1000  would be retained in first fitting  230   a  on the left-hand side of guide  216  as viewed in  FIG. 4 . Electromagnetic spectrum sensor  1000  may also be moved from the first condition to a third condition of dressing  200  so as to be in the first arrangement of the second fitting  230   b  and in the second arrangement of first fitting  230   a . Accordingly, electromagnetic spectrum sensor  1000  would be retained in second fitting  230   b  on the right-hand side of guide  216  as viewed in  FIG. 4 . Dressing  200  may also be changed between the second and third conditions—moving electromagnetic spectrum sensor  1000  to the other side of guide  216 —and may also be changed from either of the second or third conditions to the first condition—decoupling electromagnetic spectrum sensor  1000 . Accordingly, electromagnetic spectrum sensor  1000  may be used and reused with a plurality of individual dressings  200  and on whichever side of guide  216  is advantageous for a particular patient or a particular insertion site S. Factors for evaluating which of first and second fittings  230   a  and  230   b  may be advantageous to use for retaining electromagnetic spectrum sensor  1000  preferably include reducing the likelihood of pulling or snagging lead  1010 , properly placing electromagnetic spectrum sensor  1000  relative to the insertion site  2 , or patient comfort. 
     Referring additionally to  FIG. 5A , individual fittings preferably are each capable of retaining electromagnetic spectrum sensor  1000 . Preferably, individual fittings, e.g., first fitting  230   a  or second fitting  230   b , each include a pocket  232  that is defined by a wall  234 . Pocket  232  preferably receives electromagnetic spectrum sensor  1000  (shown in dash-dot line in  FIG. 5A ) in the first arrangement. Preferably, pane  210  extends across pocket  232  and is interposed between sensor surface  1000   a  and the epidermis E in the first arrangement, as shown in, e.g.,  FIG. 5A . According to one embodiment, wall  234  preferably includes a plurality of individual segments disposed partially around pocket  232 . Preferably, at least one tab  236  projects from wall  234  and overlies a portion of electromagnetic spectrum sensor  1000  in the first arrangement. Elastic deformation of wall  234  or tab  236  preferably permits electromagnetic spectrum sensor  1000  to snap-in to pocket  232  in the first arrangement and to snap-out from pocket  232  in the second arrangement. According to one embodiment, tab  236  preferably includes a raised portion or bump  238  for biasing sensor surface  1000   a  toward the epidermis E by contiguously engaging electromagnetic spectrum sensor  1000  in the first arrangement. According to other embodiments, individual fittings may include a latch, a cap, a resilient element, or another suitable device which, in a first arrangement, retains electromagnetic spectrum sensor  1000  in pocket  232  and preferably biases sensor surface  1000   a  toward the epidermis E, and in a second arrangement, releases electromagnetic spectrum sensor  1000  to move out of pocket  232 . 
     Referring additionally to  FIG. 5B , electromagnetic spectrum sensor  1000  and individual fittings in the first arrangement preferably are coupled in a desired manner. Preferably, a portion of electromagnetic spectrum sensor  1000  has a first feature that cooperates with a second feature of pocket  232 . According to one embodiment, electromagnetic spectrum sensor  1000  includes a front-side cylindrical portion  1000   b  having a first cross-section shape and pocket  232  has a second cross-section shape that matingly receives front-side cylindrical portion  1000   b . Preferably, the first and second cross-sectional shapes are approximately congruent circles or other suitable mating shapes. Portions of electromagnetic spectrum sensor  1000  other than front-side cylindrical portion  1000   b  preferably do not fit in pocket  232 . According to one embodiment, electromagnetic spectrum sensor  1000  preferably includes a backside cylindrical portion  1000   c  having a third cross-section shape, e.g., a tear drop shape, that does not matingly cooperate with the second feature of pocket  232 . Accordingly, electromagnetic spectrum sensor  1000  preferably can matingly engage individual fittings in only one manner. 
     Referring additionally to  FIG. 5C , strain relief devices preferably redirect forces from lead  1010  to dressing  200 . Preferably, individual fittings, e.g., first fitting  230   a  or second fitting  230   b , each include a set of strain relief devices that contiguously engage lead  1010  in the first arrangement. According to one embodiment, each set of strain relief devices preferably includes a first fixture  240   a  and a second fixture  240   b . Individual fixtures  240   a  or  240   b  preferably each include a pair of posts separated by a gap that is smaller than the diameter of lead  1010 . Accordingly, lead  1010  may be retained by an interference fit between a pair of posts that preferably limit lateral and/or axial movement of lead  1010  relative to frame  220 . 
     Preferably, first and second fixtures  240   a  and  240   b  are disposed on opposite sides of guide  216 . In the first arrangement, first fixture  240   a  preferably retains lead  1010  proximate a first one of the first and second fittings  230   a  and  230   b , and second fixture  240   b  preferably retains lead  1010  and tubing  32  proximate a second one of the first and second fittings  230   a  and  230   b . First fixture  240   a  of second fitting  230   b  is shown on the right-hand side of guide  216  as viewed in  FIG. 4  and second fixture  240   b  of second fitting  230   b  is shown on the left-hand side of guide  216  as viewed in  FIG. 4 . According to one embodiment, first fixture  240   a  preferably cooperates with lead  1010  to eliminate or at least minimize rotation of electromagnetic spectrum sensor  1000  in pocket  232 , and second fixture  240   b  preferably establishes a first bight  1010   a  and a second bight  32   a  for lead  1010  and tubing  32 , respectively. 
     Dressing  200  includes substantially identical features at different location options to increase compatibility of a single dressing for individual patients&#39; cases. Preferably, multiple fittings and fixtures permit selecting the best available option for positioning electromagnetic spectrum sensor  1000  relative to the insertion site S and for controlling lead  1010  and/or tubing  32 . Selecting either first fitting  230   a  or second fitting  230   b  preferably reduces the likelihood of pulling or snagging lead  1010  and/or tubing  32 , positions electromagnetic spectrum sensor  1000  proximate to the insertion site S, and increases patient comfort. 
     A clip  242  preferably couples tubing  32  and lead  1010 . Preferably, clip  242  may be fixed to lead  1010  at a selected distance from electromagnetic spectrum sensor  1000 . The distance is preferably selected to cooperate with second fixture  240   b  for consistently establishing an approximate size and radius of first bight  1010   a . According to one embodiment, clip  242  abuts against second fixture  240   b . Clip  240  preferably includes a first portion cincturing lead  1010  and a second portion having an opening for receiving and retaining, e.g., by interference fit, tubing  32 . Thus, first fixture  240   a , second fixture  240   b , and clip  242  preferably redirect to dressing  200  rather than electromagnetic spectrum sensor  1000  or cannula  20  any forces due to pulling or snagging lead  1010  and/or tube  32 . Accordingly, in the first arrangement, electromagnetic spectrum sensor  1000  may be retained in an approximately consistent positional relationship with respect to the perivascular tissue P around cannula  20  when sensing infiltration or extravasation. 
     Referring additionally to  FIG. 5D , frame  220  preferably is sufficiently flexible to conform to the approximate contours of epidermis E. Preferably, frame  220  includes one or more lines of weakness  242  disposed about frame  220  at various positions including, for example, in the general vicinity of corners for pane  210  and parallel to the longitudinal axis of cannula  20 . According to one embodiment, individual lines of weakness  242  preferably include living hinges or other suitable features for increasing the flexibility of frame  220 . 
     Dressing  200  preferably is a single unit that includes plural location options for retaining an anatomical sensor. According to one embodiment, the anatomical sensor may include electromagnetic spectrum sensor  1000  or another sensor for sensing over time a change of body structure, e.g., infiltration and extravasation. Preferably, individual fittings, e.g., first fitting  230   a  or second fitting  230   b , provide alternate location options for coupling electromagnetic spectrum sensor  1000  to dressing  200 . The location option that is most suitable is preferably selected based on one or more factors including: (i) location of the insertion site S; (ii) orientation of cannula  20 ; (iii) avoiding movement of cannula  20  or electromagnetic spectrum sensor  100  due to pulling or snagging tubing  32  or lead  1010 ; and (iv) comfort of the patient. Dressing  200  is advantageous at least because the most suitable of plural location options for coupling electromagnetic spectrum sensor  1000  is preferably selected. 
       FIGS. 6A and 6B  show embodiments of a dressing that include (i) a contamination barrier overlying the insertion site S; and (ii) different dressings  300   a  ( FIG. 6A) and 300   b  ( FIG. 6B ) for locating electromagnetic spectrum sensor  1000  (not shown in  FIG. 6A  or  6 B) to sense if fluid is infusing the perivascular tissue P around cannula  20 . As compared to dressing  200 , which includes a plurality of individual fittings at alternate location options on frame  220 , dressings  300   a  and  300   b  separately provide different locations for a fitting  330  relative to a guide  314 . Accordingly, one or the other of dressings  300   a  and  300   b , rather than one or the other of first and second fitting  230   a  and  230   b  on dressing  200 , may be selected for coupling electromagnetic spectrum sensor  1000  at the most suitable location option. 
     Dressings  300   a  and  300   b  preferably each include a pane  310 , a frame  320  and fitting  330  that are functionally similar to, respectively, pane  210 , frame  220  and first or second fitting  230   a  and  230   b . Accordingly, dressings  300   a  and  300   b  preferably each provide a contamination barrier that is substantially impervious to solids, liquids, microorganisms and/or viruses, but which may be semi-permeable to allow air or vapor to pass, thus permitting the epidermis E to breathe. Pane  310  is preferably transparent or translucent to visible light for viewing the insertion site S. Frame  320  preferably maintains the shape of pane  310  while dressing  300   a  or dressing  300   b  is laid over the insertion site S. And a first arrangement of fitting  330  preferably retains electromagnetic spectrum sensor  1000  relative to dressing  300   a  or dressing  300   b  for monitoring an intravascular infusion by cannula  20 , and a second arrangement of fitting  330  preferably releases electromagnetic spectrum sensor  1000  from the first arrangement. 
     Frame  320  preferably has greater resistance to deformation than does pane  310 . Accordingly, frame  320  may maintain the shape of pane  310  while dressing  300   a  or dressing  300   b  is laid over the insertion site S. According to one embodiment, frame  320  entirely cinctures pane  310 . According to other embodiments, frame  320  may (i) partially cincture pane  310 ; (ii) extend from a peripheral portion of pane  310  toward an interior portion of pane  310 ; (iii) extend from the interior portion toward the peripheral portion; (iv) be spaced from the peripheral portion; or (v) include a combination of (i)-(iv). Frame  320  preferably includes polyvinyl chloride, polyethylene, polypropylene, or another suitable material that is relatively rigid with respect to pane  310 . For example, frame  320  may include a pad of polyvinyl chloride foam. Frame  320  may be opaque, but is preferably transparent or translucent to visible light for viewing the epidermis E in the vicinity of the insertion site S. Preferably, frame  320  absorbs or blocks the transmission of radiation having the same wavelength as emitted electromagnetic radiation  1002 , e.g., near infrared radiation. Thus, according to one embodiment, the epidermis E that underlies frame  320  may be optically visible and shielded from ambient near-infrared radiation. 
     Dressing  300   a  and dressing  300   b  preferably are independent units that separately include different locations for retaining an anatomical sensor. Preferably, dressing  300   a  includes fitting  330  at a first location relative to guide  314 , e.g., on the right-hand side of guide  314 , and dressing  300   b  includes fitting  330  at a second location relative to guide  314 , e.g., on the left-hand side of guide  314 . Accordingly, the most suitable one of dressing  300   a  or dressing  300   b  preferably is selected based on one or more factors including: (i) location of the insertion site S; (ii) orientation of cannula  20 ; (iii) avoiding movement of cannula  20  or electromagnetic spectrum sensor  100  due to pulling or snagging tubing  32  or lead  1010 ; and (iv) comfort of the patient. Independent dressings  300   a  and  300   b  are advantageous at least because a choice is available for how an anatomical sensor is located relative to cannula  20 . 
       FIGS. 7A-7D  show an embodiment of a dressing  400  that includes (i) a frame  420  that relatively positions electromagnetic spectrum sensor  1000  and cannula  20 ; and (ii) a contamination barrier that overlies the insertion site S and frame  420 . The contamination barrier preferably is substantially impervious to solids, liquids, microorganisms and/or viruses, and may be semi-permeable to allow air or vapor to pass for permitting the epidermis E to breathe. The contamination barrier also preferably includes a pane  410  that is transparent or translucent to light in the visible portion of the electromagnetic spectrum for viewing the insertion site S. Pane  410  preferably includes a polyurethane film or another suitable material and/or construction for providing a contamination barrier that may be transparent or translucent. 
     An adhesive  412  preferably bonds the contamination barrier to the epidermis E (not indicated in  FIGS. 7A-7D ). Preferably, adhesive  412  includes an acrylic adhesive that is suitable for contact with the epidermis E or another medical grade adhesive that is biocompatible according ISO 10993 and/or USP Class VI. Adhesive  412  may be applied to the contamination barrier on the entire surface that confronts the epidermis E, or adhesive  412  may be omitted from one or more portions of the surface. For example, adhesive  412  may be omitted from a first area  412   a  on pane  410  in the vicinity of the insertion site S or from a second area  412   b  on pane  410  that may facilitate pulling pane  410  from the epidermis E. Preferably, the first or second areas  412   a  and  412   b  may be identified, e.g., with printing on pane  410 . Also, the strength of the bond between pane  410  and the epidermis E may vary according to different embodiments of dressing  400 . For example, stronger or more adhesive  412  may be used for coupling dressing  400  to relatively robust skin, e.g., adult skin, and weaker or less adhesive  412  may be used for coupling dressing  400  to relatively delicate skin, e.g., pediatric skin. Preferably, a removable backing sheet (not shown) preserves adhesive  412  until the contamination barrier is ready to be laid over the insertion site S and frame  420 . 
     Referring particularly to  FIG. 7B , a framework  414  preferably supports pane  410  while being laid over the insertion site S. Preferably, framework  414  includes paper or another suitable material that has greater resistance to deformation than does pane  410  but is flexible enough to conform to the contours of the epidermis E. Accordingly, framework  414  preferably maintains the approximate shape of the outer peripheral edge of pane  410  and of any apertures  410   a  (two are shown in  FIGS. 7A ,  7 B and  7 D) while the contamination barrier is being laid over the insertion site S and frame  420 . According to one embodiment of dressing  400 , a coupling between pane  410  and framework  414  is preferably relatively weaker than the bond between pane  410  and the epidermis E. Accordingly, framework  414  may be released after pane  410  bonds to the epidermis E. Preferably, a tab  414   a  facilitates pulling framework  414  from pane  410 . 
     Frame  420  preferably has greater resistance to deformation than does pane  410 . Preferably, frame  420  preferably includes polyvinyl chloride, polyethylene, polypropylene, or another suitable material that is relatively rigid with respect to pane  410 . For example, frame  420  may include a pad of polyvinyl chloride foam. Frame  420  preferably distributes forces, e.g., due to pulling or snagging lead  1010 , over an area of the epidermis E that is larger than that overlaid by sensor surface  1000   a.    
     Frame  420  preferably links cannula  20  and electromagnetic spectrum sensor  1000 . Preferably, frame  420  includes (i) a mount  422  for cooperatively engaging cannula  20 ; and (ii) at least one fitting—a first fitting  430   a  and a second fitting  430   b  are shown in  FIGS. 7A ,  7 C and  7 D—for coupling with electromagnetic spectrum sensor  1000 . Accordingly, frame  420  preferably includes a link for establishing and maintaining a positional relationship between cannula  20  and electromagnetic spectrum sensor  1000 . According to one embodiment, mount  422  preferably includes a base  422   a  and one or more resilient projections  422   b  extending from base  422   a . Preferably, base  422   a  includes an interface for coupling mount  422  with frame  420 , e.g., via an adhesive, and projection(s)  422   b  resiliently capture a portion of cannula  20 . Therefore, mount  422  preferably establishes and maintains a positional relationship between cannula  20  and frame  420 . Preferably, individual fittings, e.g., first fitting  430   a  or second fitting  430   b , may be comparable to the fittings discussed above regarding dressing  200  and therefore each may retain electromagnetic spectrum sensor  1000 . Therefore, each individual fitting preferably establishes and maintains a positional relationship between electromagnetic spectrum sensor  1000  and frame  420 . Thus, according to one embodiment, frame  420 , mount  422 , and first fitting  430   a  or second fitting  430   b  preferably link cannula  20  and electromagnetic spectrum sensor  1000  by establishing and maintaining their relative positional relationship. 
     Referring particularly to  FIG. 7C , frame  420  preferably prevents contiguous engagement between electromagnetic spectrum sensor  1000  and the epidermis E. Preferably, a barrier layer  420   a  extends across the pocket of individual fittings, e.g., first fitting  430   a  and second fitting  430   b , and is interposed between sensor surface  1000   a  and the epidermis E in the first arrangements of the individual fittings. Barrier layer  420   a  may be the same material as pane  410  or another material that is substantially impervious to solids, liquids, microorganisms and/or viruses, and substantially transparent to emitted and received electromagnetic radiation  1002  and  1004 . 
     Strain relief devices preferably redirect forces from electromagnetic spectrum sensor  1000  to dressing  400 . Preferably, individual fittings, e.g., first fitting  430   a  or second fitting  430   b , each include a set of strain relief devices that contiguously engage lead  1010  in the first arrangement. According to one embodiment, each set of strain relief devices preferably includes a first fixture  440   a  and a second fixture  440   b . Individual fixtures  440   a  or  440   b  preferably each include a plurality of posts separated by a gap that is smaller than the diameter of lead  1010  and/or the diameter of tubing  32 . Accordingly, lead  1010  and/or tubing  32  may be retained by a resilient interference fit between a pair of posts that preferably limit lateral and/or axial movement of lead  1010  or tubing  32  relative to frame  420 . 
     Preferably, first and second fixtures  440   a  and  440   b  are disposed on opposite sides of mount  422 . Each of  FIGS. 7A ,  7 C and  7 D indicate only one of two pairs of fixtures that are shown. In the first arrangement, first fixture  440   a  preferably retains lead  1010  proximate a first one of the first and second fittings  430   a  and  430   b , and second fixture  440   b  preferably retains lead  1010  and tubing  32  proximate a second one of the first and second fittings  430   a  and  430   b . First fixture  440   a  of first fitting  430   a  is shown on the left-hand side of mount  422  as viewed in  FIG. 7D  and second fixture  440   b  of first fitting  430   a  is shown on the right-hand side of mount  422  as viewed in  FIG. 7D . According to one embodiment, first fixture  440   a  preferably cooperates with lead  1010  to eliminate or at least minimize rotation of electromagnetic spectrum sensor  1000  with respect to first fitting  430   a , and second fixture  440   b  preferably establishes a first bight  1010   a  and a second bight  32   a  for lead  1010  and tubing  32 , respectively. 
     A method of implementing dressing  400  will now be discussed with reference to  FIG. 7D . Cannula  20  is inserted at insertion site S in a typical manner. Preferably, frame  420  is bonded to the epidermis E (not indicated) with projection(s)  422   b  of mount  422  engaging a portion of cannula  20 . Pane  410  and framework  414  preferably are overlaid on frame  420  with apertures  410   a  cincturing first fitting  430   a , second fitting  430   b , and first and second fixtures  440   a  and  440   b . Preferably, adhesive  412  bonds pane  410  to the epidermis E and framework  414  is separated from pane  410 . Adhesive  412  preferably also adheres pane  410  over the portion of cannula  20  that is engaged by mount  422  so that cannula  20  is coupled to frame  420 . Tubing  32  is coupled with cannula  20  in a typical manner and preferably also engages second fixture  440   b  to form bight  32   a . Preferably, electromagnetic spectrum sensor  1000  is coupled to an individual fitting, e.g., the fitting on the left-hand side of mount  422  as viewed in  FIG. 7D , with lead  1010  engaging first fixture  440   a . Lead  1010  preferably also engages second fixture  440   b  to form bight  1010   a . Electromagnetic spectrum sensor  1000  is thereby coupled to frame  420 . Preferably, a lead management system  450  limits the forces that may be transmitted to dressing  400  as a result of pulling or snagging tubing  32  or lead  1010 . Lead management system  450  preferably bonds to the epidermis E, e.g., with an adhesive, and includes a patch  450   a  and a board  450   b . According to one embodiment, patch  450   a  preferably is shaped and sized to overlay bights  32   a  and  1010   a , and board  450   b  preferably includes at least one fixture  450   c  that is similar to second fixture  440   b  in construction and function. Preferably, board  450   b  is spaced from bights  32   a  and  1010   a  along the lengths of tubing  32  and lead  1010 . According to one embodiment, frame  420 , patch  450   a  and board  450   b  preferably share a similar construction and may be manufactured concurrently as a unit, which may then be separated when implementing dressing  400 . 
     Removing dressing  400  preferably occurs after releasing electromagnetic spectrum sensor  1000  from the first and second fittings  430   a  and  430   b . Preferably, pane  410  is peeled off beginning with second area  412   b  while wings  420   b  (two are indicated on  FIG. 7A ) are held to separate pane  410  from frame  420 . Cannula  20  preferably is disengaged from mount  422  and extracted from the insertion site S, and frame  420  is peeled off the epidermis E. A barrier film such as Cavilon™, manufactured by 3M (St. Paul, Minn., USA), or another topical agent may be used when implementing dressing  400  for protecting the epidermis E from adhesive trauma due to peeling off pane  410  and/or frame  420 . 
     Dressing  400  is advantageous at least because there is a link between cannula  20  and electromagnetic spectrum sensor  1000  when sensing if fluid is infusing the perivascular tissue P around cannula  20 . Preferably, frame  420 , mount  422 , and individual fittings, e.g., first fitting  430   a  or second fitting  430   b , establish and maintain a relative positional relationship that links cannula  20  and electromagnetic spectrum sensor  1000 . Dressing  400  is also advantageous because a contamination barrier is implemented in a typical manner, e.g., overlying the insertion site S, and concurrently cooperates with the link between cannula  20  and electromagnetic spectrum sensor  1000 . 
       FIGS. 8A-8D  show embodiments of dressings that include (i) a contamination barrier that overlies the insertion site S for cannula  20 ; (ii) a molded frame that locates electromagnetic spectrum sensor  1000  (not shown in  FIGS. 8A-8D ) to sense if fluid is infusing the perivascular tissue P around cannula  20 ; and (iii) a plurality of options for relatively locating electromagnetic spectrum sensor  1000  and cannula  20 . Preferably, dressing  500   a  ( FIGS. 8A and 8B ) includes a first frame  520   a  that is integrally molded with a first fitting  530   a , and dressing  500   b  ( FIGS. 8C and 8D ) includes a second frame  520   b  over-molding a second fitting  530   b . The contamination barrier preferably is substantially impervious to solids, liquids, microorganisms and/or viruses, and may be semi-permeable to allow air or vapor to pass for permitting the epidermis E to breathe. 
     Employing molding to manufacture dressings  500   a  and  500   b  preferably reduces the number of independent components included in dressings  500   a  and  500   b  as compared to, for example, dressings  100 ,  200 ,  300   a / 300   b  and  400 . Preferably, the phrase “independent component” as it is used herein refers to a single part that (a) has a substantially uniform composition; and (b) is coupled with other parts in an assemblage. Dressing  500   a  preferably reduces the number of independent components by at least two as compared to, for example, dressings  100 ,  200 ,  300   a / 300   b  or  400  because (i) first frame  520   a  and first fitting  530   a  may be formed as a single independent component, e.g., integrally molded with a homogeneous chemical compound, before assembling dressing  500   a ; and (ii) an adhesive for coupling first frame  520   a  with first fitting  530   a  may be eliminated. Dressing  500   b  preferably reduces the number of independent components by at least one as compared to, for example, dressings  100 ,  200 ,  300   a / 300   b  or  400  because an adhesive for coupling first frame  520   a  with first fitting  530   a  is eliminated. Preferably, further reductions are possible in the number of independent components included in dressings  500   a  and  500   b  as compared to dressings  200  or  400 . For example, as compared to dressings  200  and  400 , a further reduction of at least one additional independent component may be possible because first or second frames  520   a  or  520   b  and strain relief device(s) for lead  1010  may be formed as a single independent component, e.g., integrally molded with a homogeneous chemical compound, before assembling dressing  500   a  or  500   b . And as compared to dressing  400 , a yet further reduction of at least two additional independent components may be possible because (i) first or second frames  520   a  or  520   b  and a mount for cannula  20  may be formed as a single independent component, e.g., integrally molded with a homogeneous chemical compound, before assembling the dressing; and (ii) an adhesive for coupling the mount with first or second frames  520   a  or  520   b  may be eliminated. Thus, employing molding may reduce the number of independent components that preferably are included in dressings  500   a  and  500   b.    
     Dressing  500   a  (or dressing  500   b ) preferably includes a pane  510 , frame  520   a  (or frame  520   b ), and fitting  530   a  (or fitting  530   b ) that function similar to, for example, pane  310 , frame  320  and fitting  330 , respectively. Accordingly, pane  510  preferably is transparent or translucent to visible light for viewing the insertion site S; frame  520   a  (or frame  520   b ) preferably maintains the shape of pane  510  while dressing  500   a  (or dressing  500   b ) is laid over the insertion site S; and a first arrangement of fitting  530   a  (or fitting  530   b ) preferably retains electromagnetic spectrum sensor  1000  relative to dressing  500   a  (or dressing  500   b ) for monitoring an intravascular infusion by cannula  20  and a second arrangement of fitting  530   a  (or fitting  530   b ) preferably releases electromagnetic spectrum sensor  1000  from the first arrangement. 
     Pane  510  preferably uses an adhesive  512  to bond with the epidermis E in the vicinity of the insertion site S. Preferably, pane  510  includes a polyurethane film or another suitable material for providing a contamination barrier that may be transparent or translucent. Adhesive  512  preferably couples pane  510  to the epidermis E. Preferably, adhesive  512  includes an acrylic adhesive that is suitable for contact with the epidermis E or another medical grade adhesive that is biocompatible according ISO 10993 and/or USP Class VI. Adhesive  512  may be applied to pane  510  on the entire surface that confronts the epidermis E, or adhesive  512  may be omitted from one or more portions of the surface. Also, the strength of the bond between pane  510  and the epidermis E may vary according to different embodiments of the dressing. For example, stronger or more adhesive  512  may be used for coupling dressing  500   a  or dressing  500   b  to relatively robust skin and weaker or less adhesive  512  may be used for coupling dressing  500   a  or dressing  500   b  to relatively delicate skin. 
     Dressings  500   a  and  500   b  each preferably include a plurality of options for positioning or orienting the dressings on the epidermis E. Preferably, dressing  500   a  includes a first guide  514   a  at a first location relative to fitting  530   a , e.g., on the right-hand side of fitting  530   a  as viewed in  FIG. 8A , and a second guide  514   b  at a second location relative to fitting  530   a , e.g., on the left-hand side of fitting  530   a  as viewed in  FIG. 8A . Similarly, dressing  500   b  includes first guide  514   a  located on the right-hand side of fitting  530   b  as viewed in  FIG. 8C , and second guide  514   b  located on the left-hand side of fitting  530   b  as viewed in  FIG. 8C . The most suitable one of first guide  514   a  or second guide  514   b  preferably is selected based on one or more factors including: (i) location of the insertion site  5 ; (ii) orientation of cannula  20 ; (iii) avoiding movement of cannula  20  or electromagnetic spectrum sensor  1000  due to pulling or snagging tubing  32  or lead  1010 ; and (iv) comfort of the patient. According to one embodiment, individual guides  514   a  and  514   b  preferably include a notch or some other feature of dressing  500   a  or  500   b  that may be sized or shaped to receive a portion of cannula  20  (not shown in  FIGS. 8A-8D ). According to another embodiment, individual guides  514   a  and  514   b  preferably include a mount (not shown) for cooperatively engaging cannula  20 . Alternate first and second guides  514   a  and  514   b  are advantageous at least because a choice is available for how electromagnetic spectrum sensor  1000  is located relative to cannula  20 . 
     First and second frames  520   a  and  520   b  preferably have greater resistance to deformation than does pane  510 . Accordingly, individual frames, e.g., first frame  520   a  or second frame  520   b , may maintain the shape of pane  510  while dressing  500   a  or dressing  500   b  is laid over the insertion site S. First and second frames  520   a  and  520   b  preferably are formed as single independent components, e.g., integrally molded with a homogenous chemical compound, rather than being built-up as a laminate. Preferably, individual frames, e.g., first frame  520   a  or second frame  520   b , include polydimethylsiloxanes or another suitable material for molding the frames. Advantageously, dressings  500   a  and  500   b  preferably resist absorbing fluids as compared to typical woven or fabric dressings. 
     First and second fittings  530   a  and  530   b  preferably are capable of retaining electromagnetic spectrum sensor  1000 . Preferably, individual fittings, e.g., first fitting  530   a  or second fitting  530   b , each include a pocket  532 , a wall  534 , and a tab  536 . Pocket  532  preferably receives electromagnetic spectrum sensor  1000  (not shown in  FIGS. 8A-8D ) in the first arrangement. Preferably, pane  510  extends across pocket  532  and is interposed between sensor surface  1000   a  and the epidermis E in the first arrangement of the individual fittings. According to one embodiment, wall  534  preferably includes a plurality of individual segments disposed partially around pocket  532 . Preferably, at least one tab  536  projects from wall  534  and overlies a portion of electromagnetic spectrum sensor  1000  in the first arrangement. Elastic deformation of wall  534  or tab  536  preferably permits electromagnetic spectrum sensor  1000  to snap-in to pocket  532  in the first arrangement and to snap-out from pocket  532  in the second arrangement. According to one embodiment, tab  536  preferably biases sensor surface  1000   a  toward the epidermis E by contiguously engaging electromagnetic spectrum sensor  1000  in the first arrangement. According to other embodiments, individual fittings may include a latch, a cap, a resilient element, or another suitable device which, in a first arrangement, retains electromagnetic spectrum sensor  1000  in pocket  532  and preferably biases sensor surface  1000   a  toward the epidermis E, and in a second arrangement, releases electromagnetic spectrum sensor  1000  from the first arrangement so as to permit movement out of pocket  532 . 
     Dressings  500   a  and  500   b  preferably maintain an approximately consistent positional relationship between electromagnetic spectrum sensor  1000  and the perivascular tissue P. According to an embodiment of dressing  500   a , frame  520   a  preferably distributes forces acting on electromagnetic spectrum sensor  1000  due to, e.g., pulling or snagging lead  1010 , over an area of the epidermis E that is larger than that overlaid by sensor surface  1000   a . Preferably, one or more arms  538  (four are shown in  FIG. 8C ) are coupled with wall  534  according to an embodiment of dressing  500   b . Arm(s)  538  preferably extend away from pocket  532 , e.g., beyond an area of the epidermis E that is overlaid by sensor surface  1000   a  in the first arrangement of fitting  530   b . Accordingly, forces acting on electromagnetic spectrum sensor  1000  due to, e.g., pulling or snagging lead  1010 , may be distributed by arm(s)  538  and frame  520   b  over an area of the epidermis E that is larger than that overlaid by sensor surface  1000   a . Dressings  500   a  and  500   b  therefore preferably enhance an approximately consistent positional relationship between electromagnetic spectrum sensor  1000  and the perivascular tissue P when sensing infiltration or extravasation. 
     Strain relief devices preferably redirect forces from lead  1010  to dressing  500   a  or dressing  500   b . Preferably, first frame  520   a  or second fitting  530   b  include at least one strain relief device that contiguously engages lead  1010  in the first arrangement. First frame  520   a  and a strain relief device  540  ( FIGS. 8A and 8B ) preferably are formed as a single independent component, e.g., integrally molded with a homogeneous chemical compound, before assembling dressing  500   a . Second fitting  530   b  and first and second fixtures  540   a  and  540   b  ( FIGS. 8C and 8D ) preferably are formed as a single independent component, e.g., integrally molded with a homogeneous chemical compound, before assembling dressing  500   b . According to an embodiment of dressing  500   b , portions of first and second fixtures  540   a  and  540   b  preferably are exposed with respect to frame  520   b . Preferably, strain relief device  540 , first fixture  540   a , and second fixture  540   b  each include a plurality of posts separated by a gap that is smaller than the diameter of lead  1010 . Accordingly, lead  1010  may be retained by a resilient interference fit between a pair of posts that preferably limit lateral and/or axial movement of lead  1010  relative to frame  520   a  or frame  520   b.    
     Molding during manufacturing of dressing  500   a  and  500   b  preferably includes at least one of (i) integrally molding a single independent component that fulfills more than one role in an assemblage; or (ii) over-molding a first independent component with another independent component in an assemblage. Preferably, first frame  520   a  is integrally molded with wall  534  and tab  536  as an independent component included in dressing  500   a . Roles including maintaining the shape of pane  510  and retaining/releasing electromagnetic spectrum sensor  1000  are therefore fulfilled by a single independent component in dressing  500   a . According to an embodiment of dressing  500   a , strain relief device  540  preferably also is integrally molded with first frame  520   a  as an independent component included in dressing  500   a . Accordingly, the additional role of limiting relative movement of lead  1010  is also fulfilled by a single independent component in dressing  500   a . According to an embodiment of dressing  500   b , preferably an initial shot in a multi-shot mold forms a first independent component and a subsequent shot in the multi-shot mold assembles dressing  500   b , including the independent component formed with the initial shot. Preferably, second frame  520   b  over-molds second fitting  530   b  in dressing  500   b . For example, wall  534  and tab  536  preferably are integrally molded with second fitting  530   b  as an independent component before being over-molded with second frame  520   b . According to embodiments of dressing  500   b , first fixture  540   a  and/or second fixture  540   b  preferably also are integrally molded with second fitting  530   b  as an independent component before being over-molded with second frame  520   b . Employing molding in manufacturing dressings  500   a  and  500   b  is advantageous at least because fewer independent components are preferably assembled as compared to, for example, dressings  100 ,  200 ,  300   a / 300   b  or  400 . 
       FIG. 9  shows an embodiment of a dressing  600  that includes (i) a contamination barrier that overlies the insertion site S for cannula  20 ; (ii) a frame that locates electromagnetic spectrum sensor  1000  (not shown in  FIG. 9 ) to sense if fluid is infusing the perivascular tissue P around cannula  20 ; and (iii) a resilient band coupling the barrier and the frame with the epidermis E. The contamination barrier preferably is substantially impervious to solids, liquids, microorganisms and/or viruses, and may be semi-permeable to allow air or vapor to pass for permitting the epidermis E to breathe. 
     Preferably, dressing  600  includes a pane  610 , a frame  620 , and a fitting  630  that function similar to, for example, pane  310 , frame  320  and fitting  330 , respectively. Accordingly, pane  610  is preferably transparent or translucent to visible light for viewing the insertion site S. Frame  620  preferably maintains the shape of pane  610  while dressing  600  is laid over the insertion site S. A first arrangement of fitting  630  preferably retains electromagnetic spectrum sensor  1000  relative to dressing  600  for monitoring an intravascular infusion by cannula  20 , and a second arrangement of fitting  630  preferably releases electromagnetic spectrum sensor  1000  from the first arrangement. 
     As compared to dressings  100 ,  200 ,  300   a / 300   b ,  400  and  500   a / 500   b , which include an adhesive coupling with the epidermis E, dressing  600  preferably includes a non-adhesive coupling with the epidermis E. Preferably, a mesh band  612  is coupled to the peripheral edge of frame  620  so as to form a loop or band for cincturing a patient&#39;s limb. Mesh band  612  is preferably resilient for maintaining contiguous engagement of dressing  600  with the epidermis E. Accordingly, dressing  600  may be advantageous when it is preferable that the contamination barrier and/or fitting  630  not adhere to the epidermis E in the vicinity of the insertion site S. 
     While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. For example, embodiments of dressings that couple electromagnetic spectrum sensor  1000  and the epidermis E may be separate from a barrier film that may also be coupled to the epidermis E. Advantageously, such dressings may be applicable with a variety of independent contamination barriers and/or cannula mounts. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.