WO2014051685A1

WO2014051685A1 - Apparatus and method for mitigating noise affecting a transcutaneous signal

Info

Publication number: WO2014051685A1
Application number: PCT/US2013/031101
Authority: WO
Inventors: Gary P. WARREN; Matthew S. Alley
Original assignee: Ivwatch, Llc
Priority date: 2012-09-27
Filing date: 2013-03-13
Publication date: 2014-04-03

Abstract

A system and method include a sensor overlying a target area of skin to aid in diagnosing subcutaneous fluid leakage. The sensor includes an absorbent that minimizes noise in detected electromagnetic radiation to make it easier to analyze a signal that is indicative of subcutaneous fluid leakage.

Description

APPARATUS AND METHOD FOR MITIGATING NOISE AFFECTING A TRANSCUTANEOUS SIGNAL

TECHNICAL FIELD

The invention relates to, for example, a sensor to aid in diagnosing at least one of infiltration and extravasation in Animalia tissue.

BACKGROUND ART

Figures 4 and 4A show a typical arrangement for intravascular infusion. As the terminology is used herein, "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 or infusate 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 V. Typically, cannula 20 is inserted through skin S at a cannulation or cannula insertion site N and punctures the blood vessel V, 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 an extracorporeal connector, e.g., a hub 20a, and a transcutaneous sleeve 20b. Fluid source 22 typically 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, Illinois, USA), are examples of typical flow control devices. Typically, cannula connector 38 and hub 20a provide a leak-proof coupling through which the fluid may flow. Luer-Lok™, manufactured by Becton, Dickinson and Company (Franklin Lakes, New Jersey, 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 32 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, California, USA) and Flo-Gard^® Volumetric Infusion Pumps manufactured by Baxter International Inc. (Deerfield, Illinois, USA) are examples of typical infusion pumps.

Intravenous infusion or therapy typically uses a fluid (e.g., infusate, whole blood, or blood product) to correct an electrolyte imbalance, to deliver a medication, or to elevate a fluid level. Typical infusates predominately consist of sterile water with electrolytes (e.g., sodium, potassium, or chloride), calories (e.g., dextrose or total parenteral nutrition), or medications (e.g., anti-infectives, anticonvulsants,

antihyperuricemic agents, cardiovascular agents, central nervous system agents, chemotherapy drugs, coagulation modifiers, gastrointestinal agents, or respiratory agents). Examples of medications that are typically administered during intravenous therapy include acyclovir, allopurinol, amikacin, aminophylline, amiodarone,

amphotericin B, ampicillin, carboplatin, cefazolin, cefotaxime, cefuroxime, ciprofloxacin, cisplatin, clindamycin, cyclophosphamide, diazepam, docetaxel, dopamine, doxorubicin, doxycycline, erythromycin, etoposide, fentanyl, fluorouracil, furosemide, ganciclovir, gemcitabine, gentamicin, heparin, imipenem, irinotecan, lorazepam, magnesium sulfate, meropenem, methotrexate, methylprednisolone, midazolam, morphine, nafcillin, ondansetron, paclitaxel, pentamidine, phenobarbital, phenytoin, piperacillin,

promethazine, sodium bicarbonate, ticarcillin, tobramycin, topotecan, vancomycin, vinblastine and vincristine. Transfusions and other processes for donating and receiving whole blood or blood products (e.g., albumin and immunoglobulin) also typically use intravenous infusion.

Unintended infusing typically occurs when fluid from cannula 20 escapes from its intended vein/artery. Typically, unintended infusing causes an abnormal amount of the fluid to diffuse or accumulate in perivascular tissue and may occur, for example, when (i) cannula 20 causes a vein/artery to rupture; (ii) cannula 20 improperly punctures the vein/artery; (iii) cannula 20 backs out of the vein/artery; (iv) cannula 20 is improperly sized; (v) infusion pump 50 administers fluid at an excessive flow rate; or (vi) the infusate increases permeability of the vein/artery. As the terminology is used herein, "tissue" preferably refers to an association of cells, intercellular material and/or interstitial compartments, and "perivascular tissue" preferably refers to cells, intercellular material and/or interstitial compartments that are in the general vicinity of a blood vessel and may become unintentionally infused with fluid from cannula 20. 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 skin S, edema, pain, or numbness. The consequences of infiltration or extravasation typically include skin reactions such as blisters, nerve compression, compartment syndrome, or necrosis. Typical treatment for infiltration or extravasation includes applying warm or cold compresses, elevating an affected limb, administering hyaluronidase, phentolamine, sodium thiosulfate or dexrazoxane, fasciotomy, or amputation.

DISCLOSURE OF INVENTION

Embodiments according to the present invention include a sensor to aid in diagnosing at least one of infiltration and extravasation in Animalia tissue. The sensor includes a first optical fiber, a second optical fiber, and a housing. The first optical fiber includes a first end face that is configured to emit a first near-infrared signal into the Animalia tissue. The second optical fiber includes a second end face that is configured to detect a second near-infrared signal from the Animalia tissue. The second near-infrared signal includes a first portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the Animalia tissue. The housing includes a near- infrared energy absorber and a surface configured to overlie the Animalia tissue. The surface cinctures the first and second end faces. The near-infrared energy absorber is configured to generally absorb a third near-infrared signal from the Animalia tissue. The third near-infrared signal includes a second portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the Animalia tissue. The third near- infrared signal impinges on the surface.

Other embodiments according to the present invention include a sensor for evaluating an anatomical change over time in subcutaneous tissue. The sensor includes a transmitter, a receiver, and a housing. The transmitter includes a first face configured to emit electromagnetic radiation toward the subcutaneous tissue. The receiver includes a second face configured to detect at least one of a first portion of transcutaneous electromagnetic radiation and a first portion of extracorporeal electromagnetic radiation. The transcutaneous electromagnetic radiation includes a portion of the electromagnetic radiation emitted from the first face that is at least one of reflected, scattered and redirected by the subcutaneous tissue. The extracorporeal electromagnetic radiation includes a portion of the electromagnetic radiation emitted from the first face that is at least one of reflected, scattered and redirected by an epidermis covering the

subcutaneous tissue. The housing includes a surface and an absorber. The surface cinctures the first and second faces and is configured to overlie the epidermis. The absorber is configured to absorb at least one of a second portion of the transcutaneous electromagnetic radiation and a second portion of the extracorporeal electromagnetic radiation. The second portions of the transcutaneous and extracorporeal

electromagnetic radiations impinge on the surface.

Other embodiments according to the present invention include a sensor for evaluating an anatomical change over time in perivascular tissue. The sensor includes an emitter face, a detector face, and an absorber. The emitter face is configured to emit a first electromagnetic radiation signal. The detector face is configured to detect a second electromagnetic radiation signal. The second electromagnetic radiation signal is at least one of a reflection, scattering and redirection of the first electromagnetic radiation signal by the perivascular tissue. The absorber is configured to absorb a third electromagnetic radiation signal. The third electromagnetic radiation signal is at least one of a reflection, scattering and redirection of the first electromagnetic radiation signal by an epidermis overlying the perivascular tissue.

Other embodiments according to the present invention include an apparatus that includes a surface configured to overlie a target area of skin, and an electromagnetic radiation absorber coupled with the surface and configured to absorb a first

electromagnetic radiation signal. The first electromagnetic radiation signal is at least one of reflected, scattered and redirected from the target area of the skin to the surface.

Other embodiments according to the present invention include a method of aiding in diagnosing at least one of infiltration and extravasation. The method includes emitting a first near-infrared signal through an epidermis, detecting a second near-infrared signal through the epidermis, and absorbing a third near-infrared signal. The second

near-infrared signal is a portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by perivascular tissue underlying the epidermis. The third near-infrared signal is a portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the epidermis.

Other embodiments according to the present invention include a method of evaluating an anatomical change over time in perivascular tissue. The method includes emitting a first electromagnetic radiation signal through an epidermis, and absorbing a second electromagnetic radiation signal. The second electromagnetic radiation signal is a first portion of the first electromagnetic radiation signal that is at least one of reflected, scattered and redirected by the epidermis.

Other embodiments according to the present invention include a method of analyzing a transcutaneous electromagnetic signal. The transcutaneous electromagnetic signal is at least one of reflected, scattered and redirected by perivascular tissue underlying an epidermis. The method includes detecting the transcutaneous

electromagnetic signal with a receiver, and absorbing an extracorporeal electromagnetic signal with the housing. The receiver is at least partially disposed in a housing that overlies the epidermis. The extracorporeal electromagnetic signal being at least one of reflected, scattered and redirected in a cavity between the housing and the epidermis. BRIEF DESCRIPTION OF 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.

Figure 1 is a schematic cross-section view illustrating an electromagnetic energy sensor.

Figure 2 is a schematic cross-section view illustrating separation of the

electromagnetic energy sensor shown in Figure 1.

Figures 2A and 2B are schematic cross-section views illustrating alternative details of area II shown in Figure 2.

Figure 3 is a schematic cross-section view illustrating an embodiment of an electromagnetic energy sensor according to the present disclosure.

Figure 3A is a plan view illustrating a superficies of the electromagnetic energy sensor shown in Figure 3.

Figure 4 is a schematic view illustrating a typical set-up for infusion administration.

Figure 4A is a schematic view illustrating a subcutaneous detail of area IVA shown in Figure 4.

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.

BEST MODE(S) FOR CARRYING OUT 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 according to the disclosure. The appearances of the phrases "one embodiment" or "other embodiments" 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.

Figure 1 shows an electromagnetic energy sensor 1000 preferably coupled with the skin S. According to one embodiment, electromagnetic energy sensor 1000 preferably operates in portions of the electromagnetic spectrum that include

wavelengths generally not harmful to tissue, e.g., wavelengths longer than at least approximately 400 nanometers. Preferably, electromagnetic energy sensor 1000 operates in the visible radiation (light) or infrared radiation portions of the

electromagnetic spectrum. According to other embodiments, electromagnetic energy sensor 1000 may operate in shorter wavelength portions of the electromagnetic spectrum, e.g., ultraviolet light, X-ray or gamma ray portions of the electromagnetic spectrum, preferably when radiation intensity and/or radiation duration are such that tissue harm is minimized.

Preferably, electromagnetic energy sensor 1000 includes an anatomic sensor. As the terminology is used herein, "anatomic" preferably refers to the structure of an Animalia body and an "anatomic sensor" preferably is concerned with sensing a change over time of the structure of the Animalia body. By comparison, a physiological sensor is concerned with sensing the functions and activities of an Animalia body, e.g., pulse, at a point in time.

Electromagnetic energy sensor 1000 preferably is arranged to overlie a target area of the skin S. As the terminology is used herein, "target area" preferably refers to a portion of a patient's skin that is generally proximal to where an infusate is being administered and frequently proximal to the cannulation site N. Preferably, the target area overlies the perivascular tissue P.

Electromagnetic energy sensor 1000 preferably uses electromagnetic radiation to aid in diagnosing infiltration or extravasation. Preferably, electromagnetic energy sensor 1000 includes an electromagnetic radiation signal transmitter 1002 and an

electromagnetic radiation signal receiver 1004. Electromagnetic radiation signal transmitter 1002 preferably includes an emitter face 1002a for emitting electromagnetic radiation 1002b and electromagnetic radiation signal receiver 1004 preferably includes a detector face 1004a for detecting electromagnetic radiation 1004b. According to one embodiment, electromagnetic radiation signal transmitter 1002 preferably includes a set of first optical fibers and electromagnetic radiation signal receiver 1004 preferably includes a set of second optical fibers. Individual optical fibers in the first or second sets preferably each have end faces that form the emitter or detector faces, respectively. Preferably, emitted electromagnetic radiation 1002b from emitter face 1002a passes through the target area of the skin S toward the perivascular tissue P. Detected electromagnetic radiation 1004b preferably includes at least a portion of emitted electromagnetic radiation 1002b that is at least one of specularly reflected, diffusely reflected (e.g., due to scattering), fluoresced (e.g., due to endogenous or exogenous factors), or otherwise redirected from the perivascular tissue P before passing through the target area of the skin S to detector face 1004a. Preferably, an accumulation of fluid in the perivascular tissue P affects the absorption and/or scattering of emitted electromagnetic radiation 1002b and accordingly affects detected electromagnetic radiation 1004b. Accordingly, electromagnetic energy sensor 1000 preferably senses changes in detected electromagnetic radiation 1004b that correspond with anatomic changes over time, such as infiltration or extravasation of the perivascular tissue P.

Emitted and detected electromagnetic radiations 1002b and 1004b preferably are in the near-infrared portion of the electromagnetic spectrum. As the terminology is used herein, "near infrared" preferably refers to electromagnetic radiation having wavelengths between approximately 600 nanometers and approximately 1,800 nanometers. These wavelengths correspond to a frequency range of approximately 500 terahertz to approximately 165 terahertz. Preferably, a desirable range in the near-infrared portion of the electromagnetic spectrum includes wavelengths between approximately 800 nanometers and approximately 1,050 nanometers. These wavelengths correspond to a frequency range of approximately 375 terahertz to approximately 285 terahertz. Emitted and detected electromagnetic radiations 1002b and 1004b preferably are tuned to a common peak wavelength. According to one embodiment, emitted and detected electromagnetic radiations 1002b and 1004b each have a peak centered about a single wavelength, e.g., approximately 970 nanometers (approximately 309 terahertz).

According to other embodiments, emitted electromagnetic radiation 1002b includes a set of wavelengths in a band between a relatively short wavelength and a relatively long wavelength, and detected electromagnetic radiation 1004b encompasses at least the band between the relatively short and long wavelengths. According to still other embodiments, detected electromagnetic radiation 1004b is tuned to a set of wavelengths in a band between a relatively short wavelength and a relatively long wavelength, and emitted electromagnetic radiation 1002b encompasses at least the band between the relatively short and long wavelengths.

Electromagnetic energy sensor 1000 preferably includes a superficies 1000a that confronts the skin S. Preferably, superficies 1000a is generally smooth and includes emitter and detector faces 1002a and 1004a. As the terminology is used herein,

"smooth" preferably refers to being substantially free from perceptible projections or indentations.

Electromagnetic energy sensor 1000 preferably is positioned in close proximity to the skin S. As the terminology is used herein, "close proximity" of electromagnetic energy sensor 1000 with respect to the skin S preferably refers to a relative arrangement that minimizes gaps between superficies 1000a and the epidermis of the skin S. Preferably, electromagnetic energy sensor 1000 contiguously engages the skin S as shown in Figure 1.

The inventors discovered a problem regarding accurately identifying the occurrence of infiltration or extravasation because of a relatively low signal-to-noise ratio of detected electromagnetic radiation 1004b. In particular, the inventors discovered a problem regarding a relatively large amount of noise in detected electromagnetic radiation 1004b that obscures signals indicative of infiltration/extravasation events. Another discovery by the inventors is that the amount of noise in detected

electromagnetic radiation 1004b tends to correspond with the degree of patient activity. In particular, the inventors discovered that detected electromagnetic radiation 1004b tends to have a relatively lower signal-to-noise ratio among patients that are more active, e.g., restless, fidgety, etc., and that detected electromagnetic radiation 1004b tends to have a relatively higher signal-to-noise ratio among patients that were less active, e.g., calm, sleeping, etc.

The inventors also discovered that a source of the problem is an imperfect cavity that may unavoidably and/or intermittently occur between superficies 1000a and the skin S. As the terminology is used herein, "imperfect cavity" preferably refers to a generally confined space that at least partially reflects electromagnetic radiation. In particular, the inventors discovered that the source of the problem is the imperfect cavity reflects portions of emitted electromagnetic radiation 1002b and/or detected electromagnetic radiation 1004b that are detected by electromagnetic radiation signal receiver 1004. Accordingly, detected electromagnetic radiation 1004b includes reflected extracorporeal electromagnetic radiation in addition to transcutaneous electromagnetic radiation. As the terminology is used herein, "extracorporeal electromagnetic radiation" generally refers to portions of emitted electromagnetic radiation 1002b and/or detected electromagnetic radiation 1004b that are reflected in the imperfect cavity, and

"transcutaneous electromagnetic radiation" preferably refers to portions of emitted electromagnetic radiation 1002b that penetrate through the skin S and are reflected, scattered or otherwise redirected from the perivascular tissue P. Preferably,

transcutaneous electromagnetic radiation includes a signal that indicates an

infiltration/extravasation event whereas extracorporeal electromagnetic radiation predominately includes noise that tends to obscure the signal. Thus, the inventors discovered, inter alia, that a cavity between superficies 1000a and the skin S affects the signal-to-noise ratio of detected electromagnetic radiation 1004b.

Figure 2 illustrates the source of the problem discovered by the inventors.

Specifically, Figure 2 shows a cavity C disposed between electromagnetic energy sensor 1000 and the skin S. The size, shape, proportions, etc. of cavity C are generally overemphasized in Figure 2 to facilitate describing the source of the problem discovered by the inventors. Preferably, emitted electromagnetic radiation 1002b includes a transcutaneous portion 1002bl that passes through the cavity C and passes through the target area of the skin S toward the perivascular tissue P. Emitted electromagnetic radiation 1002b also includes an extracorporeal portion 1002b2 that is reflected in the cavity C. Detected electromagnetic radiation 1004b preferably includes signal 1004bl as well as noise 1004b2. Preferably, signal 1004bl includes at least a portion of

transcutaneous portion 1002bl that is at least one of reflected, scattered or otherwise redirected from the perivascular tissue P before passing through the target area of the skin S, passing through the cavity C, and being received by electromagnetic radiation signal receiver 1004. Noise 1004b2 includes at least a portion of extracorporeal portion 1002b2 that is reflected in the cavity C before being received by electromagnetic radiation signal receiver 1004.

Figures 2A and 2B illustrate that the cavity C preferably includes one or an aggregation of individual gaps. Figure 2A shows individual gaps between superficies 1000a and the skin S that, taken in the aggregate, preferably make up the cavity C.

Preferably, the individual gaps may range in size between approximately microscopic gaps Gl (three are indicated in Figure 2A) and approximately macroscopic gaps G2 (two are indicated in Figure 2A). It is believed that approximately microscopic gaps Gl may be due at least in part to epidermal contours of the skin S and/or hair on the skin S, and approximately macroscopic gaps G2 may be due at least in part to relative movement between superficies 1000a and the skin S. Patient activity is an example of an occurrence that may cause the relative movement that results in approximately macroscopic gaps G2 between superficies 1000a and the skin S.

Figure 2B shows electromagnetic energy sensor 1000 preferably isolated from the skin S by a foundation 1010. Preferably, foundation 1010 contiguously engages superficies 1000a and contiguously engages the skin S. Accordingly, the cavity C between foundation 1010 and the skin S preferably includes an aggregation of (1) approximately microscopic gaps Gl (two are indicated in Figure 2A); and (2) approximately macroscopic gaps G2 (two are indicated in Figure 2A). Foundation 1010 preferably is coupled with respect to electromagnetic energy sensor 1000 and includes a panel 1012 and/or adhesive 1014. Preferably, panel 1012 includes a layer disposed between electromagnetic energy sensor 1000 and the skin S. Panel 1012 preferably includes Tegaderm™, manufactured by 3M (St. Paul, Minnesota, USA), REACTIC™, manufactured by Smith & Nephew (London, UK), or another polymer film, e.g., polyurethane film, that is substantially impervious to solids, liquids, microorganisms and/or viruses. Preferably, panel 1012 is transparent or translucent with respect to visible light, breathable, and/or biocompatible. As the terminology is used herein, "biocompatible" preferably refers to compliance with 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). Other regulatory entities, e.g., National Institute of Standards and Technology, may also promulgate standards that may additionally or alternatively be applicable regarding biocompatibility. Panel 1012 preferably is generally transparent with respect to emitted and detected electromagnetic radiations 1002b and 1004b. Preferably, adhesive 1014 bonds at least one of panel 1012 and electromagnetic energy sensor 1000 to the skin S. Adhesive 1014 preferably includes an acrylic adhesive, a synthetic rubber adhesive, or another biocompatible, medical grade adhesive. Preferably, adhesive 1014 minimally affects emitted and detected

electromagnetic radiations 1002b and 1004b. According to one embodiment, as shown in Figure 2B, adhesive 1014 preferably is omitted where emitted and detected

electromagnetic radiations 1002b and 1004b penetrate foundation 1010, e.g., underlying emitter and detector faces 1002a and 1004a.

Figure 3 shows an electromagnetic energy sensor 1100 according to the present disclosure that preferably includes a housing 1110 with an electromagnetic radiation absorber 1130. According to one embodiment, housing 1110 preferably includes a first housing portion 1112 coupled with a second housing portion 1114. Preferably, electromagnetic radiation signal transmitter 1002 and electromagnetic radiation signal receiver 1004 extend through a space 1116 generally defined by housing 1110. Housing 1110 preferably includes a biocompatible material, e.g., polycarbonate, polypropylene, polyethylene, acrylonitrile butadiene styrene, or another polymer material. A potting material 1120, e.g., epoxy, preferably fills space 1116 around electromagnetic radiation signal transmitter 1002 and electromagnetic radiation signal receiver 1004. According to one embodiment, potting material 1120 preferably cinctures transmitting and receiving optical fibers disposed in space 1116. Preferably, housing 1110 includes a surface 1118 that confronts the skin S and cinctures emitter and detector faces 1002a and 1004a. Accordingly, as shown in Figure 3A, a superficies 1102 of electromagnetic energy sensor 1100 preferably includes emitter face 1002a, detector face 1004a and surface 1118.

Absorber 1130 preferably absorbs electromagnetic radiation that impinges on surface 1118. As the terminology is used herein, "absorb" or "absorption" preferably refer to transforming electromagnetic radiation to another form of energy, such as heat, while propagating in a material. Preferably, absorber 1130 absorbs wavelengths of electromagnetic radiation that generally correspond to the wavelengths of emitted and detected electromagnetic radiations 1002b and 1004b. According to one embodiment, absorber 1130 preferably absorbs electromagnetic radiation in the near-infrared portion of the electromagnetic spectrum. Absorber 1130 may additionally or alternatively absorb wavelengths in other parts of the electromagnetic radiation spectrum, e.g., visible light, short-wavelength infrared, mid-wavelength infrared, long-wavelength infrared, or far infrared. Preferably, absorber 1130 absorbs at least 50% to 90% or more of the electromagnetic radiation that impinges on surface 1118.

Absorber 1130 preferably includes a variety of form factors for inclusion with housing 1110. Preferably, absorber 1130 includes at least one of a film, a powder, a pigment, a dye, or ink. Film or ink preferably are applied on surface 1118, and powder, pigment or dye preferably are incorporated, e.g., dispersed, in the composition of housing 1110. Figure 3 shows absorber 1130 preferably is included in first housing portion 1112; however, absorber 1130 or another electromagnetic radiation absorbing material may also be included in second housing portion 1114 and/or potting material 1120. Examples of absorbers 1130 that are suitable for absorbing near-infrared electromagnetic radiation preferably include at least one of antimony-tin oxide, carbon black, copper phosphate, copper pyrophosphate, illite, indium-tin oxide, kaolin, lanthanum hexaboride, montmorillonite, nickel dithiolene dye, palladium dithiolene dye, platinum dithiolene dye, tungsten oxide, and tungsten trioxide.

Absorber 1130 preferably improves the signal-to-noise ratio of received electromagnetic radiation 1004 by reducing noise 1004b2. Compared to electromagnetic energy sensor 1000 (Figure 2), the propagation of extracorporeal portion 1002b2 preferably is substantially attenuated by absorber 1130 in electromagnetic energy sensor 1100. Preferably, extracorporeal portion 1002b2 that impinges on surface 1118 is absorbed rather than being reflected in the cavity C and therefore does not propagate further, e.g., toward electromagnetic radiation signal receiver 1004. Other

electromagnetic radiation that impinges on surface 1118 preferably is also absorbed rather than being reflected in the cavity C. For example, absorber 130 may also absorb a portion of transcutaneous portion 1002bl that is at least one of reflected, scattered or otherwise redirected from the perivascular tissue P, then passes through the target area of the skin S and through the cavity C, but impinges on surface 1118 rather than being received by electromagnetic radiation signal receiver 1004.

Electromagnetic energy sensor 1100 preferably may be used, for example, (1) as an aid in detecting at least one of infiltration and extravasation; (2) to identify an anatomical change in perivascular tissue; or (3) to analyze a transcutaneous

electromagnetic signal. Preferably, electromagnetic radiation signal transmitter 1002 transmits emitted electromagnetic radiation 1002b via emitter face 1002a. Emitted electromagnetic radiation 1002b preferably propagates through foundation 1010 and/or cavity C, if either of these is disposed in the path of emitted electromagnetic radiation 1002b toward the target area of the skin S. According to one embodiment, emitted electromagnetic radiation 1002b divides into transcutaneous portion 1002bl and extracorporeal portion 1002b2 in the cavity C.

Transcutaneous portion 1002bl of emitted electromagnetic radiation 1002b preferably propagates through the skin S toward the perivascular tissue P. Preferably, at least a portion of transcutaneous portion 1002bl is at least one of reflected, scattered or otherwise redirected from the perivascular tissue P toward the target area of the skin S as signal 1004bl. After propagating through the target area of the skin S, signal 1004bl preferably further propagates through the cavity C and foundation 1010, if either of these is disposed in the path of signal 1004bl toward electromagnetic radiation signal receiver 1004. Preferably, electromagnetic radiation signal receiver 1004 receives signal 1004bl via detector face 1004a. Signal 1004bl preferably includes a transcutaneous

electromagnetic signal that may be analyzed to, for example, identify anatomical changes in perivascular tissue and/or aid in detecting an infiltration/extravasation event.

Extracorporeal portion 1002b2 of emitted electromagnetic radiation 1002b is reflected in cavity C, but preferably is generally absorbed by absorber 1130. Preferably, absorber 1130 absorbs at least 50% to 90% or more of extracorporeal portion 1002b2 that impinges on surface 1118. Accordingly, a first portion of noise 1004b2 due to extracorporeal portion 1002b2 preferably is substantially eliminated or at least reduced by absorber 1130.

Absorber 1130 preferably also absorbs a second portion of noise 1004b2 due to electromagnetic radiation other than extracorporeal portion 1002b2 in cavity C. For example, absorber 1130 preferably also absorbs a portion of signal 1004bl that impinges on surface 1118 rather than being received by electromagnetic radiation signal receiver 1004 via detector face 1004a.

Thus, absorber 1130 preferably improves the signal-to-noise ratio of detected electromagnetic radiation 1004b by absorbing noise 1004b2. Preferably, reducing noise 1004b2 in detected electromagnetic radiation 1004b makes it easier to analyze signal 1004bl in detected electromagnetic radiation 1004b.

Changes in the size and/or volume of cavity C preferably may also be used to monitor patient activity and/or verify inspections by caregivers. Preferably, information regarding the frequency and degree of patient motion may be detected by

electromagnetic energy sensor 1100. Accordingly, this information may aid a caregiver in evaluating if a patient is obsessed with or distracted by cannula 20 and therefore at greater risk of disrupting the patient's infusion therapy. Similarly, electromagnetic energy sensor 1100 preferably may be used to detect caregiver inspections of the target area of the skin and/or the insertion site N. Preferably, a caregiver periodically inspects the patient during infusion therapy for indications of infiltration/extravasation events. These inspections preferably include touching and/or palpitating the target area of the patient's skin; which tends to cause relative movement between electromagnetic energy sensor 1100 and the skin. Accordingly, a record of detected electromagnetic radiation 1004b preferably includes the occurrences over time of caregiver inspections.

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. 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. INDUSTRIAL APPLICABILITY

Administering fluids, medications and parenteral nutrition by intravenous infusion therapy is one of the most common procedures in health care. In the United States, approximately 80 percent of patients admitted to hospitals receive intravenous infusion therapy and up to 330,000,000 or more peripheral intravenous administration sets are sold annually. Sensors according to the present disclosure may be used to aid in detecting infusate infiltration and/or extravasation during intravenous infusion therapy. Sensors according to the present disclosure may also be used to monitor blood transfusions or in connection with intravenous infusion therapy for Animalia in addition to human patients.

SEQUENCE LISTING

Not Applicable

Claims

CLAIM OR CLAIMS What is claimed is:

1. A sensor to aid in diagnosing at least one of infiltration and extravasation in Animalia tissue, the sensor comprising:

a first optical fiber including a first end face configured to emit a first near-infrared signal into the Animalia tissue;

a second optical fiber including a second end face configured to detect a second near-infrared signal from the Animalia tissue, the second near-infrared signal including a first portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the Animalia tissue; and

a housing including:

a surface configured to overlie the Animalia tissue, the surface cincturing the first and second end faces; and

a near-infrared energy absorber configured to generally absorb a third near-infrared signal from the Animalia tissue, the third near-infrared signal including a second portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the Animalia tissue; wherein the third near-infrared signal impinges on the surface.

2. The sensor of claim 1 wherein the first and second optical fibers extend through the housing.

3. The sensor of claim 2, comprising a potting material being disposed in the housing and cincturing the first and second optical fibers.

4. The sensor of claim 1 wherein a generally smooth superficies comprises the first end face, the second end face and the surface.

5. The sensor of claim 1 wherein the near-infrared energy absorber comprises at least one of a film, a powder, a pigment, a dye, and ink.

6. The sensor of claim 5 wherein at least one of the film and ink are disposed on the surface.

7. The sensor of claim 5 wherein the housing includes at least one of the powder, the pigment and the dye.

8. The sensor of claim 1 wherein the near-infrared energy absorber comprises at least one of antimony-tin oxide, carbon black, copper phosphate, copper pyrophosphate, illite, indium-tin oxide, kaolin, lanthanum hexaboride, montmorillonite, nickel dithiolene dye, palladium dithiolene dye, platinum dithiolene dye, tungsten oxide, and tungsten trioxide.

9. A sensor for evaluating an anatomical change over time in subcutaneous tissue, the sensor comprising:

a transmitter including a first face configured to emit electromagnetic radiation toward the subcutaneous tissue;

a receiver including a second face configured to detect at least one of a first portion of transcutaneous electromagnetic radiation and a first portion of extracorporeal electromagnetic radiation, the transcutaneous electromagnetic radiation including a portion of the electromagnetic radiation emitted from the first face that is at least one of reflected, scattered and redirected by the subcutaneous tissue, and the extracorporeal electromagnetic radiation including a portion of the electromagnetic radiation emitted from the first face that is at least one of reflected, scattered and redirected by an epidermis overlying the subcutaneous tissue; and

a housing including a surface and an absorber, the surface cincturing the first and second faces and being configured to overlie the epidermis, and the absorber being configured to absorb at least one of a second portion of the transcutaneous

electromagnetic radiation and a second portion of the extracorporeal electromagnetic radiation, wherein the second portions of the transcutaneous and extracorporeal electromagnetic radiations impinge on the surface.

10. The sensor of claim 9 wherein the transmitter comprises a plurality of optical fibers, and the first face includes individual faces of the plurality of first optical fibers.

11. The sensor of claim 9 wherein the receiver comprises a plurality of optical fibers, and the second face includes individual faces of the plurality of second optical fibers.

12. The sensor of claim 9, comprising a generally smooth superficies including the first end face of the transmitter, the second end face of the receiver, and the surface of the housing.

13. The sensor of claim 9 wherein the housing comprises first and second housing portions, the first housing portion includes the surface, and the second housing portion is coupled to the first housing portion.

14. The sensor of claim 13 wherein the first and second housing portions generally define a space in the housing, and the transmitter and receiver are at least partially disposed in the space.

15. The sensor of claim 9 wherein the housing comprises a polymer and the absorber is generally dispersed in the polymer.

16. The sensor of claim 15 wherein the polymer consists of at least one of

polycarbonate, polypropylene, polyethylene and acrylonitrile butadiene styrene.

17. The sensor of claim 9 wherein the absorber is configured to absorb at least approximately 50% of the second portions of the transcutaneous and extracorporeal electromagnetic radiations.

18. The sensor of claim 9 wherein the absorber is configured to absorb at least approximately 90% of the second portions of the transcutaneous and extracorporeal electromagnetic radiations.

19. The sensor of claim 9 wherein the absorber comprises a near-infrared energy absorber configured to absorb a band of wavelengths between approximately 600 nanometers and approximately 1,800 nanometers.

20. The sensor of claim 19 wherein the band of wavelengths is between

approximately 800 nanometers and approximately 1,050 nanometers.

21. The sensor of claim 9, comprising a foundation coupled to the surface, the foundation being configured to generally contiguously engage the epidermis.

22. The sensor of claim 21 wherein the foundation is configured to be substantially transparent to (i) the electromagnetic radiation emitted from the first face; (ii) the first portion of transcutaneous electromagnetic radiation; and (iii) the first portion of extracorporeal electromagnetic radiation.

23. The sensor of claim 9 wherein the surface is configured to generally contiguously engage the epidermis.

24. A sensor for evaluating an anatomical change over time in perivascular tissue, the sensor comprising:

an emitter face configured to emit a first electromagnetic radiation signal;

a detector face configured to detect a second electromagnetic radiation signal, the second electromagnetic radiation signal being at least one of a reflection, scattering and redirection of the first electromagnetic radiation signal by the perivascular tissue; and an absorber configured to absorb a third electromagnetic radiation signal, the third electromagnetic radiation signal being at least one of a reflection, scattering and redirection of the first electromagnetic radiation signal by epidermis overlying the perivascular tissue.

25. The sensor of claim 24, comprising a superficies configured to confront the epidermis, the superficies includes the emitter face, the detector face, and a surface of the absorber.

26. The sensor of claim 25 wherein the surface cinctures the emitter and detector faces.

27. The sensor of claim 24 wherein the first, second and third electromagnetic radiation signals comprise near-infrared signals.

28. The sensor of claim 27 wherein the absorber comprises a near-infrared absorber configured to absorb a band of electromagnetic radiation signals having wavelengths between approximately 600 nanometers and approximately 1,800 nanometers.

29. The sensor of claim 28 wherein the band of electromagnetic radiation signals have wavelengths between approximately 800 nanometers and approximately 1,050 nanometers.

30. An apparatus comprising:

a surface configured to overlie a target area of skin; and

an electromagnetic radiation absorber coupled with the surface and configured to absorb a first electromagnetic radiation signal that is at least one of reflected, scattered and redirected from the target area of the skin to the surface.

31. The apparatus of claim 30 wherein the surface is configured to confront the target area of the skin.

32. The apparatus of claim 31 wherein the surface is configured to be spaced from the target area of the skin.

33. The apparatus of claim 31 wherein the surface is configured to be partially contiguous with the target area of the skin.

34. The apparatus of claim 30 wherein the electromagnetic energy absorber is disbursed in a body including the surface.

35. The apparatus of claim 30 wherein the electromagnetic radiation absorber comprises a near-infrared radiation absorber configured to absorb a band of

electromagnetic radiation signals having wavelengths between approximately 800 nanometers and approximately 1,050 nanometers.

36. The apparatus of claim 30 wherein the electromagnetic radiation absorber comprises a near-infrared radiation absorber consisting of at least one of a film, a powder, a pigment, a dye, and ink.

37. The apparatus of claim 30, comprising:

a detector face cinctured by the surface and configured to detect a second electromagnetic radiation signal that is at least one of reflected, scattered and redirected by perivascular tissue underlying the target area of the skin; and an emitter face cinctured by the surface and configured to emit a third electromagnetic radiation signal through the target area of the skin toward the perivascular tissue;

wherein the first electromagnetic radiation signal includes a first portion of the third electromagnetic radiation signal and the second electromagnetic radiation signal includes a second portion of the third electromagnetic radiation signal.

38. The apparatus of claim 37, comprising:

a first optical fiber including the detector face; and

a second optical fiber including the emitter face.

39. The apparatus of claim 37 wherein the second electromagnetic radiation signal is configured to aide in diagnosing at least one of infiltration and extravasation.

40. A method of aiding in diagnosing at least one of infiltration and extravasation, the method comprising:

emitting a first near-infrared signal through an epidermis;

detecting a second near-infrared signal through the epidermis, the second near-infrared signal being a portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by perivascular tissue underlying the epidermis; and absorbing a third near-infrared signal, the third near-infrared signal being a portion of the first near-infrared signal that is at least one of reflected, scattered and redirected by the epidermis.

41. The method of claim 40 wherein signal peaks of the first, second and third near- infrared signals are centered about a common wavelength.

42. The method of claim 41 wherein the common wavelength of the signal peaks of the first, second and third near-infrared signals is centered between approximately 600 nanometers and approximately 1,800 nanometers.

43. The method of claim 41 wherein the common wavelength of the signal peaks of the first, second and third near-infrared signals is centered between approximately 800 nanometers and approximately 1,050 nanometers.

44. The method of claim 40 wherein absorbing the third near-infrared signal comprises absorbing the third near-infrared signal through a first portion of a superficies overlying the target area.

45. The method of claim 44 wherein emitting the first near-infrared signal comprises emitting the first near-infrared signal through a second portion of the superficies, the first portion of the superficies cincturing the second portion of the superficies.

46. The method of claim 44 wherein detecting the second near-infrared signal comprises detecting the second near-infrared signal through a third portion of the superficies, the first portion of the superficies cincturing the third portion of the superficies.

47. The method of claim 44 wherein absorbing the third near-infrared signal comprises absorbing at least approximately 50% of the third near-infrared signal that impinges on the first portion of the superficies.

48. The method of claim 44 wherein absorbing the third near-infrared signal comprises absorbing at least approximately 90% of the third near-infrared signal that impinges on the first portion of the superficies.

49. The method of claim 44, comprising absorbing a fourth near-infrared signal, the fourth near-infrared signal being a portion of the first near-infrared signal that is reflected, scattered and redirected by the perivascular tissue.

50. The method of claim 49 wherein absorbing the fourth near-infrared signal comprises absorbing at least approximately 50% of the fourth near-infrared signal that impinges on the first portion of the superficies.

51. The method of claim 49 wherein absorbing the fourth near-infrared signal comprises absorbing at least approximately 90% of the fourth near-infrared signal that impinges on the first portion of the superficies.

52. A method of evaluating an anatomical change over time in perivascular tissue, the method comprising: emitting a first electromagnetic radiation signal through an epidermis; and absorbing a second electromagnetic radiation signal, the second electromagnetic radiation signal being a first portion of the first electromagnetic radiation signal that is at least one of reflected, scattered and redirected by the epidermis.

53. The method of claim 52 wherein the second electromagnetic radiation signal impinges on a surface of a housing, and absorbing the second electromagnetic radiation signal includes the housing absorbing the second electromagnetic radiation signal.

54. The method of claim 53 wherein emitting the first electromagnetic radiation signal comprises a first end face of a first optical fiber emitting the first electromagnetic radiation signal.

55. The method of claim 54 wherein the surface cinctures the first end face, and the housing cinctures at least a portion of the first optical fiber.

56. The method of claim 55 wherein a superficies configured to confront the epidermis includes the first end face and the surface.

57. The method of claim 53, comprising detecting a third electromagnetic radiation signal through the epidermis, the third electromagnetic radiation signal being a second portion of the first electromagnetic radiation signal that is at least one of reflected, scattered and redirected by perivascular tissue underlying the epidermis.

58. The method of claim 57 wherein emitting the first electromagnetic radiation signal includes a first end face of a first optical fiber emitting the first electromagnetic radiation signal, and detecting the third electromagnetic radiation signal includes a second end face of a second optical fiber detecting the third electromagnetic radiation signal, the surface cinctures the first and second end faces, and the housing cinctures at least a portion of the first optical fiber and at least a portion of the second optical fiber.

59. The method of claim 58 wherein a superficies configured to confront the epidermis includes the first end face, the second end face, and the surface.

60. A method of analyzing a transcutaneous electromagnetic signal, the

transcutaneous electromagnetic signal being at least one of reflected, scattered and redirected by perivascular tissue underlying an epidermis, the method comprising: detecting the transcutaneous electromagnetic signal with a receiver, the receiver being at least partially disposed in a housing overlying the epidermis; and

absorbing an extracorporeal electromagnetic signal with the housing, the extracorporeal electromagnetic signal being at least one of reflected, scattered and redirected in a cavity between the housing and the epidermis.

61. The method of claim 60 wherein the receiver includes a detector face, and the housing includes a surface cincturing the detector face.

62. The method of claim 61 wherein a generally smooth superficies confronting the epidermis includes the detector face and the surface.

63. The method of claim 61 wherein at least one of the detector face and the surface partially contiguously engage the epidermis.

64. The method of claim 60, comprising emitting an electromagnetic signal with a transmitter, the transcutaneous electromagnetic signal including a first portion of the electromagnetic signal that is at least one of reflected, scattered and redirected by perivascular tissue, and the extracorporeal electromagnetic signal including a second portion of the electromagnetic signal that is at least one of reflected, scattered and redirected in the cavity.

65. The method of claim 64 wherein the receiver includes a detector face, the transmitter includes an emitter face, and the housing includes a surface cincturing the detector and emitter faces.

66. The method of claim 65 wherein a generally smooth superficies confronting the epidermis includes the detector face, the emitter face, and the surface.

67. The method of claim 66 wherein at least one of the detector face, the emitter face, and the surface partially contiguously engage the epidermis.

68. The method of claim 60 wherein absorbing the extracorporeal electromagnetic signal improves a signal-to-noise ratio of the transcutaneous electromagnetic signal.

69. The method of claim 60, comprising cavity changes in response to relative movement of the housing and the epidermis, the cavity changes include at least one of cavity shape change and cavity volume change.

70. The method of clam 69, comprising monitoring patient motion based on at least one of the cavity changes.

71. The method of claim 69, comprising monitoring epidermis inspection frequency based on at least one of the cavity changes.