Patent Grant
8980174
This invention generally relates to methods and systems for reducing the risk of patient bloodstream infection by microorganisms during administration of various medications and fluids through lines. In particular, the invention relates to methods and systems for reducing the count of infectious agents and inhibiting the growth of microorganisms in the vicinity of the point of entry of a catheter into a patient's body.
It is a common practice in medicine to administer various medications and fluids into and withdraw blood from a patient's vascular system. For these purposes, various intravenous access devices exist. Such a device typically has a hollow needle, the tip of which is inserted into a patient's blood vessel for variable periods of time—from seconds (for example, injections and blood sampling) to a year (for example, total parenteral nutrition, chemo-therapy and dialysis). All such devices bypass several natural anti-infection defense barriers and introduce a risk of direct bloodstream contamination. The general terms for these devices is “lines.” The type of infection that arises from the use of such “lines” is called “line sepsis.” Elaborate and complicated precautions and prevention techniques are in use, and include use of one or more of the following means: sterile equipment, sterile insertion technique, aseptic handling techniques, replacement of the “lines” as indicated by various protocols, antibiotics, and antibacterial substances impregnated into catheters.
One of the unsolved problems that is especially relevant to intravascular catheters with longer time of use is colonization by microorganisms of the area in the immediate vicinity of the point of entry of the catheter into the body. Various means are presently used to maintain sterility of a catheter insertion site. For example, once an intravenous access device is inserted into a blood vessel, a dressing is applied to the area around the insertion site. The dressing provides a physical barrier to prevent contamination of the site by infectious agents.
Dressings are periodically changed. Care is needed to ensure that infectious agents do not contaminate the site. For example, during a dressing change, an antiseptic wipe may be used to sterilize the insertion site. Other materials used for changing a dressing, such as gloves and wipes, must also be sterile.
These methods of cleaning and disinfecting the area around the point of insertion of a catheter into a patient's body are of low efficacy. Decontamination of indwelling devices may also be problematic because the patient, his blood, and the administered medicine are potentially exposed to all of the physical, chemical and pharmacological effects of such decontamination.
There is a need for improved apparatus and improved methods for reducing the risk of patient bloodstream infection by microorganisms which may contaminate the catheter insertion area.
The present invention is directed to methods, systems and devices for reducing catheter-related bloodstream infections. The technology disclosed herein starts fighting the bacteria immediately, at the point of insertion of a catheter into a human body, thereby stopping bacteria proliferation at an early stage.
Recent photobiology research has shown that various types of microorganisms can be eradicated by irradiation with visible light, especially in the “violet/blue spectral region.” As used herein, the term “violet/blue spectral region” refers to blue light comprising wavelengths in the range of 455-492 nm and violet light comprising wavelengths in the range of 390-455 nm, consistent with the definitions of “blue” and “violet” given in the Academic Press Dictionary of Science and Technology, Harcourt Brace Jovanovich, New York (1992). The various bactericidal devices disclosed herein each comprise a light source that preferably emits light having wavelengths in the violet/blue spectral region.
The apparatus and methods disclosed herein can prevent patient bloodstream infection by microorganisms during administration of various medications or fluids via a catheter. In particular, the invention reduces contamination by microorganisms by means of irradiation with violet and/or blue light. Each of the embodiments disclosed herein comprises a source of violet and/or blue light installed such that light from the light source is directed toward a point of entry of a catheter into a human body. Preferably, a light-emitting diode or a laser diode that emits light in the desired wavelength (i.e., in the violet/blue spectral region) can be used.
One aspect of the invention is a method for reducing the count of infectious agents at a catheter entry point, comprising the following steps: (a) placing an optical element so that any transmitted light will be directed toward the point of catheter entry; (b) optically coupling the optical element to a source of light; and (c) causing the light source to emit light, the emitted light being transmitted by the optical element toward the catheter entry point, wherein the emitted light has a bactericidal effect.
Another aspect of the invention is a system for reducing the count of infectious agents at a catheter entry point, comprising: an optical element placed so that transmitted light will be directed toward the catheter entry point; and a source of light optically coupled to the optical element, wherein when the light source emits light, the emitted light is transmitted by the optical element toward the catheter entry point, wherein the emitted light has a bactericidal effect.
A further aspect of the invention is a system comprising a device consisting of a holder or housing having light sources emitting light having wavelengths in the range of 390-492 nm. The device is affixed to or supported near the catheter insertion site and is positioned such that light from the light sources is incident on the area of the skin in the immediate vicinity of the area of catheter insertion.
The device disclosed herein may be affixed over a transparent dressing overlying the catheter entry point, or may be used independent of such a dressing. The device may be affixed to the catheter insertion site using an adhesive or fastening band, or through other methods. Depending on context, the device may be used continuously or periodically, and may be affixed such that it is directly abutting a transparent dressing or directly adjacent to the skin surface, or it may be spaced a certain distance from the skin. If spaced from the skin, light may be directed from the light sources, either directly or indirectly through optical conduits. Preferably the light sources will be positioned such that light from the light sources overlaps at one or more areas on the skin, especially the catheter entry point.
Other aspects of the invention are disclosed below.
Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.
Recent photobiology research has showed that various types of microorganisms can be eradicated by irradiation of visible light, especially light in the violet/blue spectral region. The photo-contamination reduction effect has been shown for both in vivo and in vitro setups.
Elman et al. [see Elman, M., et al., “The effective treatment of acne vulgaris by a high-intensity, narrow band 405-420 nm light source,” J. Cosmetic and Laser Therapy, 5(2), pp. 111-117 (June 2003)] applied narrow-band light at 405-420 nm for treatment of acne vulgaris. Recently the FDA approved narrow-band, high-intensity light therapy for treating acne. Light works by killing the acne-causing bacteria, P. acnes, and is being used to treat inflammatory acne vulgaris that has not responded to other acne therapies. Current light products do not contain ultraviolet (UV) light, which was a staple of former light therapy used to treat acne. UV light can damage skin and is no longer used to treat acne.
Enwemeka et al. [see Enwemeka, C. S., Williams, D., Hollosi, S., Yens, D., and Enwemeka, S. K., “Visible 405 nm SLD light photo-destroys methicillin-resistant Staphylococcus aureus (MRSA) in vitro,” Lasers Surg. Med., 40(10), pp. 734-737 (December 2008)] studied the photo-sterilization effect of light at 405 nm on methicillin-resistant Staphylococcus aureus (MRSA) in vitro. According to Enwemeka et al., maximum eradication of the US-300 (92.1%) and the IS-853 colonies (93.5%) was achieved within 9.2 and 8.4 minutes of exposure, respectively. According to the authors, the effect was non-linear as increases of energy densities between 1.0 and 15 J/cm2 resulted in more bacteria death than similar increases between 15 and 60 J/cm2.
Fukui et al. [see Fukui, M., Yoshioka, M., Satomura, K., Nakanishi, H., and Nagayama, M., “Specific-wavelength visible light irradiation inhibits bacterial growth of Porphyromonas gingivalis,” J. Periodontal Res., 43(2), pp. 174-178 (April 2008)] showed that the growth of Porphyromonas gingivalis bacteria irradiated at 400 and 410 nm was significantly suppressed compared with a nonirradiated control, whereas wavelengths of 430 nm and longer produced no significant inhibition. A constant energy density of 15 J/cm2 was found to be enough to show an inhibitory effect. Significant inhibition of bacterial growth was found after only 1 min at 50 mW/cm2 irradiation.
Guffey et al. [see Guffey, J. S., and Wilbom, J., “In vitro bactericidal effects of 405-nm and 470-nm blue light,” Photomed. Laser Surg., 24(6), pp. 684-688 (December 2006)] showed that both 405-nm and 470-nm irradiation have a bactericidal effect on Staphylococcus aureus and Pseudomonas aeruginosa bacteria in vitro. The 405-nm light produced a dose-dependent bactericidal effect on Pseudomonas aeruginosa and Staphylococcus aureus (p<0.05), achieving a kill rate of 95.1% and nearly 90%, respectively. The 470-nm light effectively killed Pseudomonas aeruginosa at all dose levels, but only killed Staphylococcus aureus at 10 and 15 J/cm2. With this wavelength, as much as 96.5% and 62% reduction of Pseudomonas aeruginosa and Staphylococcus aureus was achieved, respectively. Neither of the two wavelengths proved to be bactericidal with respect to anaerobic Propionibacterim acnes.
Guffey et al. [see Guffey, J. S., and Wilborn, J., “Effects of combined 405-nm and 880-nm light on Staphylococcus aureus and Pseudomonas aeruginosa in vitro,” Photomed. Laser Surg., 24(6), pp. 680-683 (December 2006)] showed that combined irradiation of Staphylococcus aureus by 405 and 800 nm has a bactericidal effect.
The mechanisms involved in the photo-contamination reduction effect of blue/violet light are still a subject for numerous research efforts. The violet light in the 400-420 nm wavelength range interacts with the Soret absorption band of porphyrins. The higher wavelength blue light around 440-480 nm interacts with absorption band of flavins and riboflavine. The longer wavelength white light and near infra-red (NIR) light interact with cytochromes and higher absorption bands of porphyrins. The absorbed light excites these photosensitizers while subsequent relaxation from the excited state occurs by transferring electrons to O2, thereby generating reactive oxygen species (ROS). When the ROS reach some increased value, they destroy the cell. The phenomenon is known as phototoxicity.
The present invention enables the provision of systems and methods for continuous (during use) contamination reduction of the area around the point of insertion of a catheter into a human body. The various embodiments of the invention are designed to illuminate this area with light having wavelengths in the range of 390-492 nm and emitted by low-cost light sources such as light-emitting diodes (LEDs) or laser diodes.
As used herein, the terms “light-emitting diode” and “laser diode” refer to devices comprising a semiconductor diode and an optical element optically coupled to that diode for shaping the radiation pattern of the light emitted by the diode. As used herein, the terms “light-emitting diode assembly” (or “LED assembly”) and “laser diode assembly” refer to assemblies comprising either an LED or a laser diode mounted on or embedded within control circuitry.
The absorption band of flavins [i.e., flavin-adenine dinucleotide (FAD)] is shown in
A typical catheter 300 is shown in
Risks associated with catheters include infection, due to continued presence of a foreign body in a blood vessel, and due to continued presence of an opening in the skin. To reduce these risks, a dressing is typically placed over the catheter insertion site. The dressing may be a traditional dressing, or may be a transparent, semipermeable dressing, such as Tegaderm™ brand dressings from 3M of St. Paul, Minn., USA.
Embodiments of the invention described herein utilize a housing having light-emitting elements for irradiating a catheter insertion site with light having wavelengths in a specific anti-microbial range. The transparency of the transparent dressing described above in the visible part of the spectrum allows violet and/or blue light to be transmitted through these materials from a LED or laser chip to the location of potential microorganism contamination. Although some attenuation of the violet and/or blue light in the elastomer material occurs, such attenuation is not so great (since the optical path is a few millimeters in most cases) as to interfere with delivery of the level of irradiation with violet and/or blue light required to effectively target the contamination reduction site.
Similar transmission cannot be achieved with UV light, which is highly absorbed in the plastics, so the same contamination reduction effect cannot be achieved using UV LEDs: UV light propagating into transparent window material will be immediately attenuated and therefore be practically ineffective. On the other side of the spectrum, the green, red or NIR LEDs will be much less effective since, as shown in
An additional advantage of contamination reduction of human skin in the vicinity of the catheter needle insertion point through a transparent dressing window is human safety. The violet and/or blue light is safe to medical personnel and patients, whereas a similar device based on UV irradiation would be unsafe for the users.
As shown in
According to an embodiment of the present invention shown in
As shown in
The device 500 may have power and control electronics to provide power to light-emitting elements 504 and to allow control of the device, including switching the light-emitting elements 504 on, timing controls for the light-emitting elements 504, and other necessary control functions. The device 500 may have attachment hooks 522 for holding straps 624 (omitted from
As shown in an alternative embodiment 600 depicted in
The device 600 may have power and control electronics to provide power to light-emitting elements 604 and to allow control of the device, including switching the light-emitting elements 604 on, timing controls for the light-emitting elements 604, and other necessary control functions. The device 600 may have attachment hooks 622 for holding straps 624 (omitted from
In
In
An alternate installed configuration 802 is depicted in
An alternate installed configuration 902 is depicted in
In any of these embodiments, light may be transmitted from the contamination reduction device to a patient's skin either directly through the air, or via optical conduits. An example of a configuration utilizing a contamination reduction device in conjunction with an optical conduit is shown in
In
First, the optical conduit enhances optical coupling by allowing for efficient transmission of light from light emitting elements to a patient's skin. Because the material used for the transparent window in a transparent window dressing may have a refractive index which differs greatly from that of air, lack of an optical conduit may lead to a high amount of back reflection of emitted light. Use of optical conduits as described above provides a smoother transition in refractive indices from the point at which the light is emitted to the patient's skin.
Second, having the optical conduit may serve as a thermal insulator, which significantly hinders the transfer of heat from the light-emitting elements. Illumination of a patient's skin for long periods of time may cause an uncomfortable buildup of heat, which can be prevented with appropriate use of a thermal insulator. The optical conduit can therefore serve the double purpose of efficient light transfer and blockage of heat transfer. The device, in any of the embodiments presented herein, may also be used with a heat sink, to draw heat away from the light emitting elements.
Operational parameters for the contamination reduction devices disclosed above may be varied to suit different needs. The timing and duration of irradiation, the length of time for which the device is installed, and other timing parameters may be varied depending on the setting in which the irradiation device is to be used. For example, in a hospital setting, the device may be attached continuously, and include a timer for automatic activation. For out-patient use, the device may be used much less frequently, and may be applied to a catheter insertion site only when required, such as several times a day for a short period of only several minutes. The device may include a timer with an alarm or reminder which reminds a patient or caretaker to install and activate the device at pre-scheduled times and for pre-determined periods. Also, the device may include control circuitry configured to control activation timing and activation duration of the light-emitting elements. For example, the control circuitry may be capable of activating the light-emitting elements in one of a variety of timing patterns, including a constant timing pattern, a pulsed timing pattern, a time limited timing pattern, and the like.
The light-emitting diodes used in any of the embodiments disclosed herein may be configured to emit light at roughly the same wavelength as each other, or may be configured such that all lights do not emit roughly the same wavelength as each other.
Additional features may be provided for added convenience. A cradle shaped to conform to the device's geometry may be provided and may act as a charger. The cradle may contain wiring to plug into a wall socket, and may have electrical terminals for connection with and recharging of the device. The cradle may be powered by standard electrical power supply, i.e. 90-240 V and 50-60 Hz. Recharging may start automatically when the device is placed into the cradle and the electrical terminals make contact with the corresponding terminals on the device. The cradle may also use a contact-less recharging mechanism, such as an electrical induction circuit, to recharge the batteries or otherwise provide power to the device. Batteries or other on-board power supply may be rechargeable, and may preferably have at least 96 hours of charge time.
The cradle may also have a port for connection to a computing device. Such a port may be any port capable of providing power and/or data to said housing, such as, for example, a USB port. The device may be controlled through said port, for example, by ordering light-emitting elements on the device on or off. The device may also be monitored, for example, by collecting data regarding how long the device has been on or off, by recording the history of activation of the device (i.e., a history of device usage, including times and durations during which the device has been on or off), and the like.
Preferably, the device is comprised of materials that are lightweight, spill-proof, and that allow the device to be wiped by disinfecting medical fluids such as alcohol and chlorohexidine. The device may have some permanent and some disposable parts. For example, the optical conduit may be disposable. Further, adhesive tape or adhesive components, clamps, or straps/bands used to secure the device to its intended location may be disposable as well.
The device may have buttons and/or indicator lights for power, control and various indications. A single on/off push-button, or on button and off button may be provided on the device. Indicators lights indicating that the device is currently providing illumination, that the device is currently charging, and that battery or other on-board power is low may also be provided. The device may also include displays indicating the time elapsed from last illuminating sequence, an illumination sequence selector for selecting a pre-set or pre-programmed illumination sequence, and a small switch for turning light emitting elements off when the door 606 is in a disengaged position.
The structures disclosed herein also have application in systems wherein the bactericidal radiation is light having a wavelength outside the violet/blue spectral region.
Although described as used in the context of a peripheral venous catheter, due to the fact that items which penetrate the body and remain in such a position for a prolonged period of time may present a risk of infection, it is contemplated that the contamination reduction device disclosed herein may be used with any element that projects into a human body, including other types of catheters, orthopedic pins, or other types of needles, pins or tubes that are inserted into a patient's skin, or any other like device.
While the invention has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention.
This application is a U.S. National Stage of International Application No. PCT/US2012/037533 filed May 11, 2012, which claims priority to U.S. Provisional Application No. 61/485,926 filed May 13, 2011, both applications of which are incorporated by reference herein in their entireties.
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| PCT/US2012/037533 | 5/11/2012 | WO | 00 | 6/5/2012 |
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