Patent Application
20130035629
Many medical disorders are treated with light energy. Tissue may be exposed to light energy to bond, coagulate, debride, sclerose or sterilize it. In addition, tissue may be irradiated with light to stimulate a variety of biological responses including accelerated healing. In addition monochromatic coherent light, monochromatic or polychromatic noncoherent can be therapeutically useful. Applications for exposure span beyond the medical field, with needs for light energy in many areas of industrial manufacturing, food processing, biological research and laboratory testing and analysis. Traditional light delivery systems include optical lenses or fiberoptics which transmit light to provide exposure to a target tissue area. Many medical delivery systems illuminate a circumferential area with a radius of 200 microns to 1 centimeter. Shaped fiber tips can alter the size or shape of the exposed area. Alternatively, light can be delivered to a lens or collimation system to alter the size or shape of delivered energy. All of these devices function in a non-contact mode. Contact fiberoptic tips (e.g. sapphire tips) exist which are heated by light and have a variety of tip contours. The hot tip is then brought in contact with the target tissue to produce the therapeutic effects desired. These existing delivery devices expose a fixed shape (usually circular) to light. Spot sizes vary but they are usually between 0.5 mm and 5 mm.
Areas of tissue that have been wounded are often quite large. Moreover, areas of tissue requiring exposure to light therapy, may be irregular in contour (i.e. mountainous rather than flat). Further, areas of tissue requiring exposure to light may have a contour other than basically flat—i.e. circumferential exposure of tubular structures. When treating such areas it is often difficult to expose the entire area without omitting parts of the area creating “skip zones” that are not adequately treated. This can result in therapeutic failure particularly in the case of light treatment of infected wounds. An excessive amount of time may be required to expose the entire treatment area.
The ability to sterilize open wounds or various types of surgical repairs, especially prior to evidence of infection, is another valuable medical application. Various types of dressings are typically used to seal such surfaces using adhesives or mechanically bandaged in place. These can be mechanically removed or can spontaneously delaminate after a period of time exposing the wounded surface to a series of lethal pathogens. Alternatively, the dressing may be absorbed by the body or hydrated and loosened. The dressings may be impregnated with medications, pharmaceuticals, drugs, growth factors, hormones, enzymes or cells to promote healing, prevent inflammation or thrombosis or other pharmacologic or biological effects. These medications must be re-administered periodically and typically become less effective over time.
Consistent with the present disclosure, a delivery system (device, apparatus) is provided for delivering electromagnetic radiation, such as light. The delivery system may include a light activated antimicrobial dressing and a method for using the same. Preferably, the system or device simultaneously exposes an area of target material to a uniform or nearly uniform power density of light. Alternatively, the device may expose an area of target material to a range of power densities which will produce a similar effect or a predictable effect in the target material. In addition, the device may alternatively expose an area of target material to electromagnetic radiation, or coherent monochromatic light or monochromatic light or polychromatic light. Alternatively, the device may deliver or generate electromagnetic radiation for exposure of a diffusing material of the device to generate reactive oxygen ions so that, for example, antimicrobial therapy may be applied to a target tissue.
The device may include several components: 1) an energy transmitting or producing shielding element; 2) a dispersing or diffusing element; 3) a collagen composite mat containing a photosensitizer element, 4) a status sensor element. Some variations of the device may also include: a reflecting element or support.
An energy transmitting element may take energy from a source to which it was coupled and bring this energy to the dispersing or diffusing element, directly to the target material or directly or indirectly to the reflecting element. This component may effect such transportation of energy with a minimum of change in the amount, intensity, and spatial and temporal conformation of the energy. An example of such a transmitting element may include a lens assembly having a collecting or focusing lens. With standard optical coupling to a light emitting device, the lens assembly may transmit the energy, preferably substantially unattenuated, to the dispersing or diffusing element, directly to the target material, or directly or indirectly to the reflecting element.
An energy producing, generating or emitting element may be a component which produces or emits energy which may be, but is not limited to, electromagnetic radiation, polychromatic light, monochromatic non-coherent light, monochromatic coherent light. Examples of this include lasers, diode lasers, light emitting diodes and incandescent bulbs. These may be positioned in such a way as to provide exposure to all or part of the target material or to have an additive effect in conjunction with other cooperatively positioned energy producing elements. Multiple types of energy producing elements may be included for simultaneous or sequential exposure of the target material to produce the desired effects.
The dispersing or diffusing element may be composed of a material which absorbs the input energy at an interface or junction with the transmitting element or energy producing element. This energy is then radiated from the dispersing or diffusing element across its entire surface area, for example, to provide exposure of the target material. This element may be flexible so that it conforms to the target material. In some cases the device may be shaped or formed to produce a cavity, with or without an aperture, which is air filled, the air acting as the dispersing or diffusing element.
The reflecting element typically does not absorb the incident energy but reflects it. The reflecting element may redirect the incident energy, prevent scatter, concentrate the intensity of the energy, and/or redirect or return energy back-scattered, emitted or reflected from the target material or for integrating, smoothing or otherwise modifying the incident energy. Such directing or redirecting may be to or towards the dispersing or diffusing element or a focusing element or the target material. Such integrating or smoothing may produce a more uniform power density, or a non-uniform power density with a specific spatial conformation or a range of power densities with essentially the same or with a predictable or known effect.
A composite material mat may be added on the surface of the diffuser and contacts the tissue. The composite material may be bioresorbable or permanent. This may include material that, when exposed to the incident energy, releases reactive oxygen ions (or reactive oxygen species) that destroy or kill pathogens that cause infection in the tissue. The composition may include a collagen layer with incorporated photosensitive chromophores such as riboflavin, lumichrome or lumiflavin. In another aspect of this disclosure, the collagen composition may be chemically reacted with the chromophore. Once the chromophore is dissolved or incorporated into the collagen composition, the layer or thin film is removed from solution and purified dried to remove any excess chromophore.
A status sensor element that monitors a specific endpoint of exposure may also be provided. This element may alternatively monitor the depletion of the photosensitive chromophore.
The shielding device may be configured as a rectangle, square or other geometric shape. Possible compositions of the shielding component include polyvinyl chloride (PVG), polyethylene (PE), polypropylene (PP), polycarbonate and thermoplastic polyesters, and elastomers and copolymers. Polyvinyl chloride backbone polymers can be formulated with a variety of additives to produce a compound as hard as glass or as soft as gum rubber. To improve tensile strength, resins with higher molecular weights are selected. These polymers are processed by extrusion or injection molding processes. The selection of a plasticizer or processing with elastomers can increase the material flexibility. Autoclaving can be used to change device shape. PVC is a plastic that may be used for short-term, external contact to the body. This material can be extruded into sheets or thin films for additional variation in the conformation of this element of the invention. Four different ethylene based polymer types, with distinct properties, processing characteristics and applications are achievable with varying material density. Typically, the higher the density, the higher the strength, chemical resistance,softening point, stiffness and the lower the optical clarity. In comparison, decreasing density will improve flexibility, impact and tear resistance, sealability and clarity. Therefore, different formulations of this material may be suitable for the shielding and the diffusing element. PVC may be processed by extrusion, injection molding and blow molding methods. In one example, high density polyethylene formulations will be appropriate where a sterile breathable bandage or wound shield is required while low density PE materials will be used as a wound cover, sealant and light trap because of excellent tensile and puncture resistance and flexibility.
Polycarbonate exhibits ductility, dimensional stability, clarity, temperature resistance and biocompatibility. All common molding techniques are currently in use to produce a variety of product shapes. Polycarbonate can be bonded to itself or to other materials by means of a variety of agents and techniques including solvents, adhesives, ultrasonic welding, thermal and vibrational welding. This material may be used as the shielding element especially where there is need to join the shielding element to the diffusing element as part of this invention.
A light source or an array of sources may be assembled with a reflective component that adheres to the inside surface of the rectangle shielding device. The exit face of the rectangle may have affixed to it an additional skirt to prevent leakage of any light from within the exposure chamber. This skirt may be shielding but may also be flexible, stretchable and conformal to the surface of the composite material to insure good seal.
The source of light may be a laser, a diode laser or light emitting diode (LED). As one specific example, one or more emitter/generators may be embedded in the interior (light reflecting) surface of the rectangle. These emitter/generators may produce identical or different power levels. In this case the light device is either mechanically affixed to the shield at a specific point of entry or alternatively can become an integral part of the shield body. The latter example is particularly feasible for semiconductor light emitting diodes. Each diode is embedded into the polymeric material at some processing step such as in the molding process. The diodes may be positioned exactly such that each emitting area is projecting light on the underside of the shield and toward the diffuser element surface. The electrical leads for powering the diodes will also be encapsulated but will have terminal connectors for external connection to a power supply or battery. Further control of the emitting light can be accomplished by including optical elements such as collimating and focusing lens assemblies. The focal length of the focusing lens can be selected to vary spot size (power density) and distance to collagen composite surface. These elements could be incorporated with the diode at the molding processing step of the plastic shield element.
The shape of the shielding device need not be rectangular. It may be alternatively be hemicylindrical, irregular or another geometric shape depending on the size and shape of the area to be exposed depending on the application as well as the desired distribution of energy over that area. It is sometimes necessary to achieve specific therapeutic, manufacturing or processing ends to expose the composite material to a non-uniform density of energy. For example scattering of light within a tissue tends to cause deposit of a higher overall amount of energy in the center of the composite material. It therefore could be necessary for uniform tissue effect to increase the amount of exposure at the periphery of the target site. Other variations in distribution are necessary because of variations in tissue contour, type and other factors. Shape of the reflecting surface or position, intensity or number of light emitters could produce the necessary variation in exposure powers.
Consistent with a further aspect of the present disclosure, the collagen composite layer may be formulated to produce a flexible conformal mat which could be draped over or wrapped around the wound. An outer layer of shielding material would cover the mat. This would be pierced at one or more locations by a transmitting element. Alternatively, energy generating or emitting elements could be embedded on the undersurface (exposure surface) of the mat. These energy generating or emitting elements could be powered by an external or internal power supply. An external power supply could be transmitted by wire or by induction of current in transforming coils within the generating element. Internal power supplies could include batteries and/or capacitors.
The undersurface of the dispersing medium would be in contact with the collagen composite material. This material could include collagen, derivatized collagen, gelatin and a mixture of collagen and gelatin. The material could be imbued with riboflavin, lumichrome, lumiflavin and medications.
The conformation of the mat can be variable. It can be oval rectangular, square or round. It can have single or multiple energy inputs or emitters/generators. It can be spatulate and ribbon-like. It can be cylindrical shaped or produce an inner lumen. The cylinder can have a slit along its length to allow application around circumferential structures. The size and thickness of the device can vary depending on requirements of the applications and the power density/distribution desired.
Consistent with an additional aspect of the present disclosure, a layer may be provided to treat infected tissue or a wound which comprises a composition of collagen and a chromophore, such as riboflavin, lumichrome, lumiflavin, as well as combinations including two or more of the foregoing, and applying that layer on a surface of the infected tissue or wound. The invention also includes directing a beam of photoradiation toward the collagen composition that includes riboflavin provided on the surface of the tissue or wound such that the beam exposes the composition to the photoradiation, the photoradiation including light having a wavelength in a range of 360-375 nm or 440-480 nm with power densities ranging from 0.1 W/cm2 to 2 W/cm2. In one example, the radiation is light having a wavelength of 455 nm.
The sensor may measure pressure, strain, flow of the collagen composition, and/or the property of light (e.g., wavelength or intensity) reflected, emitted, and/or absorbed by the collagen composition. The sensor may be incorporated within the light shield. Electronics or control circuitry may be included on the control unit circuit card and may be electrically connected to the sensor via a cable. Once the photosensitizer has been depleted, the sensor signal may output change or signal indicating that the exposure is completed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one (several) embodiment(s) of the invention and together with the description, serve to explain the principles of the invention.
a is a plan view showing the pad illustrated in
b is a cross-sectional view of the pad shown in
a, 10b, 11, and 12 illustrate examples of the operation of exemplary pads consistent with the present disclosure.
Reference will now be made in detail to the present exemplary embodiments, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Consistent with an additional aspect of the present disclosure, a concentration of the riboflavin in the composite layer 102 is within a range of 0.1% to 2.0% (w/w). Consistent with a further aspect of the present disclosure, the concentration of the riboflavin in the composite layer is substantially equal to 1.0%. Further, the chromophore may include lumichrome, and the collagen may be gelatinized.
The diffused light may next pass through an optional plastic sheet 204, which includes a material that is substantially transparent to the light emitted by sources 208.
As further shown in
In one example, composite layer 102 may be provided on intermediate layer 104, as noted above. In particular, in the example shown in
Alternatively, composite layer 102 and intermediate layer 104, including Tegaderm®, may be provided separate from the rest of the components of pad 106 shown in
It is noted that the present disclosure is not limited to the number of batteries shown in 5. Rather any appropriate number of batteries may be provided based on the electrical power requirements of sources 208 and current and/or voltage ratings of the batteries or battery.
In the examples discussed above, the power supply (e.g., batteries) and control circuitry 506 is housed within frame 202 of pad 106. Consistent with an additional aspect of the present disclosure, however, the power supply, e.g. battery or batteries may be provided remote from the apparatus 100. For example, as shown in
a illustrates a plan view of apparatus or pad 801. Apparatus 801 includes a waveguide 902 which connects to fiber 812. In the example shown in
b illustrates a cross-sectional view of apparatus or pad 801 taken along line B-B shown in
Operation of apparatus 100 and 801 will next be described with reference to
b illustrates another example in which composite layer 102 is bonded or attached to intermediate layer 104. The unattached or unbounded side of composite layer 102 may be placed in contact with wound 1010. Then pad 106, i.e., a surface of optical diffuser 206, may be brought into contact with the unbonded or unattached side of intermediate layer 104, as indicated by arrows 1020. Optical sources 208 may then be activated as noted above to generate light that passes though optical diffuser 206 and intermediate layer 104 to expose composite layer 104.
Accordingly, consistent with the present disclosure, a method is provided in which the composite layer (102) is applied to a biological tissue, e.g. wound portion or layer 1010 of tissue 1012. Then, in one example, composite layer 102 is exposed with light transmitted through intermediate layer 104, the light having a wavelength in a range of 440 nm to 480 nm, such as 455 nm.
Upon exposure to the emitted light, the chromophore in composite layer 102 may generate or provide a reactive oxygen species that destroys or kills pathogens present in wound or tissue 1010. Significant reductions in bacterial or pathogen counts have been observed consistent with the present disclosure. In one example, a bacterial count of a known MRSA bacteria was reduced 99.88% relative to a control bacterial count without the application of the composite layer and exposure of such layer.
After exposure, apparatus 100 may be removed, leaving composite layer 102 on the treated wound 1010 (see
An advantage associated with composite layer 102 is that it is believed to be non-toxic to the surrounding tissue, e.g., tissue surrounding wound 101. Conventional silver ion dressings, as noted above, however, may be toxic to the treated tissues, as well as surrounding tissue.
It is understood that apparatus 801 may be applied to wound 1010 in a manner similar to that described above in connection with apparatus 100, and that apparatus 801 may similarly be removed from wound subsequent to exposure of light from waveguide 902. Also, it is understood, that apparatus 801 may be reused by providing a new, unexposed composite layer on intermediate layer 104.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example, a sensor may be provided in apparatus 100 or 801 to sense an amount of light absorbed by composite layer 102, for example, to determine an exposure end point. Control circuitry discussed above may be coupled or in communication with the sensor to receive a sense signal supplied by the sensor, and, in response to the sense signal, the control circuitry may control the power (voltage or current) supplied to the optical sources. For example, an appropriate sense signal may be generated by the sensor after the chromophore has completed its release of reactive oxygen, and, in response to that sense signal, the control circuitry may deactivate the optical sources.
It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This application claims the benefit of provisional application No. 61/515,315 filed Aug. 4, 2011, the entire content of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61515315 | Aug 2011 | US |
