U.S. patent application number 10/641894 was filed with the patent office on 2004-02-19 for method and apparatus for sterilizing or disinfecting a region through a bandage.
This patent application is currently assigned to UV-Solutions, LLC. Invention is credited to Eckhardt, Richard, Jenkins, Geoffrey H., Kimball, Sandra.
Application Number | 20040034398 10/641894 |
Document ID | / |
Family ID | 27501748 |
Filed Date | 2004-02-19 |
United States Patent
Application |
20040034398 |
Kind Code |
A1 |
Eckhardt, Richard ; et
al. |
February 19, 2004 |
Method and apparatus for sterilizing or disinfecting a region
through a bandage
Abstract
Methods and apparatus for sterilizing or disinfecting a region
through a bandage. One embodiment of the invention is directed to a
method, comprising acts of determining the transmissivity of at
least a portion of a bandage to ultraviolet light, and selecting an
intensity of ultraviolet light to be applied through at least a
portion of the bandage. Another embodiment of the invention is
directed to a method of sterilizing or disinfecting a region
underneath a bandage on a patient. A further embodiment of the
invention is directed to an apparatus for sterilizing or
disinfecting a region of tissue of a patient. The apparatus
comprises an ultraviolet light-emitting lamp and a bandage adapted
to transmit at least some of the ultraviolet light emitted by the
lamp. Another embodiment of the invention is directed to a bandage,
comprising an ultraviolet light-transmissive film, and a
color-changing material coupled to the film to indicate an exposure
of the film to ultraviolet light.
Inventors: |
Eckhardt, Richard;
(Arlington, MA) ; Jenkins, Geoffrey H.; (Wellesley
Hills, MA) ; Kimball, Sandra; (Boston, MA) |
Correspondence
Address: |
Randy J. Pritzker
Wolf, Greenfield & Sacks, P.C.
Federal Reserve Plaza
600 Atlantic Avenue
Boston
MA
02210
US
|
Assignee: |
UV-Solutions, LLC
Wellesley Hills
MA
|
Family ID: |
27501748 |
Appl. No.: |
10/641894 |
Filed: |
August 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10641894 |
Aug 15, 2003 |
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10173129 |
Jun 17, 2002 |
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60298790 |
Jun 15, 2001 |
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60300803 |
Jun 25, 2001 |
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60316744 |
Aug 31, 2001 |
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60334722 |
Oct 31, 2001 |
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Current U.S.
Class: |
607/94 |
Current CPC
Class: |
A61N 2005/0645 20130101;
A61M 39/16 20130101; A61M 2039/167 20130101; A61L 2/0047 20130101;
A61B 90/50 20160201; A61M 25/00 20130101; A61N 5/0624 20130101;
A61L 2/10 20130101; A61M 2025/0019 20130101; A61N 2005/0661
20130101 |
Class at
Publication: |
607/94 |
International
Class: |
A61N 001/00 |
Claims
What is claimed is:
1. A method of sterilizing or disinfecting a region underneath a
bandage on a patient, comprising an act of: applying ultraviolet
light to the region through the bandage.
Description
PRIORITY CLAIM
[0001] This application is a continuation of U.S. Ser. No.
10/173,129 entitled "Method and Apparatus for Sterilizing or
Disinfecting a Region Through a Bandage," filed Jun. 17, 2002,
which claims the benefit, under 35 U.S.C. .sctn.119(e), of the
filing date of: U.S. provisional application serial No. 60/298,790
entitled "Method and Apparatus for Disinfecting Catheters and
Entrance Sites," filed Jun. 15, 2001; U.S. provisional application
serial No. 60/300,803 entitled "Method and Apparatus for
Disinfecting Catheters and Entrance Sites," filed Jun. 25, 2001;
U.S. provisional application serial No. 60/316,744 entitled "Method
and Apparatus for Disinfecting Wound Sites," filed Aug. 31, 2001;
and U.S. provisional application serial No. 60/334,722 entitled
"Method and Apparatus for Disinfecting Catheter Entrance Sites with
a Dressing," filed Oct. 31, 2001; which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
sterilization or disinfection systems and methods.
BACKGROUND OF THE INVENTION
[0003] Infection is a primary concern in health care settings.
Bacteria and other potentially harmful microbes can generate
infections when they enter the body through wounds, catheter
entrance sites, and other openings in the body, thereby bypassing
the body's natural defenses. Infections, often absent at the time
of admission to a hospital, are a serious source of morbidity,
mortality, and excess cost in health care settings.
[0004] Catheters, a frequent conduit into the body for
microorganisms, are typically sterilized before insertion into the
body. Further, regions of skin that are or will be breached are
typically treated with antiseptic or germicidal chemicals. As
evidenced by the continued high rate of infection of catheter
entrance sites and/or wounds, it is clear that the present
techniques for sterilizing these regions are inadequate.
[0005] While ultraviolet radiation has been used for the
sterilization of disinfection of objects in some applications,
ultraviolet light has long been associated with skin cancer,
sunburns, and other harmful skin effects. Common wisdom and
practice has encouraged the non-exposure of skin to ultraviolet
radiation.
SUMMARY OF THE INVENTION
[0006] One embodiment of the invention is directed to a method of
sterilizing or disinfecting a region underneath a bandage on a
patient. The method comprises an act of applying ultraviolet light
to the region through the bandage.
[0007] Another embodiment of the invention is directed to an
apparatus for sterilizing or disinfecting a region of tissue of a
patient. The apparatus comprises an ultraviolet light-emitting lamp
and a bandage adapted to transmit at least some of the ultraviolet
light emitted by the lamp. The bandage covers at least a portion of
the region of tissue.
[0008] A further embodiment of the invention is directed to a
method, comprising acts of determining the transmissivity of at
least a portion of a bandage to ultraviolet light, and selecting an
intensity of ultraviolet light to be applied through at least a
portion of the bandage. Another embodiment of the invention is
directed to a bandage, comprising an ultraviolet light-transmissive
film and a color-changing material coupled to the film to indicate
an exposure of the film to ultraviolet light.
[0009] A further embodiment of the invention is directed to a
device for use with a catheter inserted at an entrance site through
skin of a patient. The device comprises a component having a
conduit to retain the catheter and space the catheter from the skin
of the patient near the entrance site, wherein the component is
located and shaped such that the component assists in forming a
substantially air-tight seal between the skin and a bandage adhered
to at least a part of the component.
[0010] Another embodiment of the invention is directed to a device
for use with a catheter inserted at an entrance site through skin
of a patient. The device comprises a component having a conduit to
retain the catheter and space the catheter from the skin of the
patient near the entrance site, wherein the component is located
and shaped such that the component assists in forming a
substantially light-tight seal between the skin and a bandage
adhered to at least a part of the component. A further embodiment
of the invention is directed to a method of using an
ultraviolet-transmissive bandage. The method comprises acts of
applying the bandage over skin of a patient, and applying
ultraviolet light through the bandage to the skin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates a method for sterilizing or disinfecting
a region of skin or tissue with a light source;
[0012] FIG. 2 illustrates a method for sterilizing or disinfecting
a catheter entrance site with a light source;
[0013] FIGS. 3 and 4A-4E illustrate an instantaneous
sterilization/disinfection unit;
[0014] FIGS. 5A-5C illustrate a continuous process
sterilization/disinfect- ion unit;
[0015] FIGS. 6A-6B illustrate a light directing component for use
with a sterilization/disinfection unit;
[0016] FIGS. 7A-7C illustrate the light directing component of
FIGS. 6A-6B used with the instantaneous sterilization/disinfection
unit of FIGS. 3 and 4A-4E;
[0017] FIG. 8 illustrates a first embodiment of a UV-transmissive
bandage;
[0018] FIGS. 9A-9B illustrate another embodiment of a
UV-transmissive bandage;
[0019] FIGS. 10A-9C illustrate a further embodiment of a
UV-transmissive bandage;
[0020] FIGS. 11A-11B illustrate another embodiment of a
UV-transmissive bandage;
[0021] FIG. 12 illustrates the instantaneous
sterilization/disinfection unit of FIGS. 3 and 4A-4E used with a
UV-transmissive bandage;
[0022] FIG. 13 illustrates the continuous process
sterilization/disinfecti- on unit of FIGS. 5A-5C used with a
UV-transmissive bandage;
[0023] FIGS. 14A-14C illustrate the instantaneous
sterilization/disinfecti- on unit of FIGS. 3 and 4A-4E used with
the light directing component of FIGS. 6A-6B and a UV transmissive
bandage;
[0024] FIG. 15 illustrates a self-sterilizing attachment coupled to
the instantaneous sterilization/disinfection unit of FIGS. 3 and
4A-4E;
[0025] FIG. 16 illustrates a block diagram of exemplary circuitry
for use in the instantaneous sterilization/disinfection unit of
FIGS. 3 and 4A-4E; and
[0026] FIG. 17 illustrates a schematic diagram of exemplary
circuitry for use in the instantaneous sterilization/disinfection
unit of FIGS. 3 and 4A-4E.
DETAILED DESCRIPTION
[0027] As mentioned above, ultraviolet light is potentially harmful
to the skin. Consequently, many individuals take precautions
against exposure. Because of its perceived dangerous nature,
ultraviolet light has not been contemplated for the sterilization
or disinfection of skin, including wounded skin and healthy skin,
or catheter entrance sites.
[0028] In view of the foregoing, one aspect of the present
invention is directed to a method and apparatus for sterilizing or
disinfecting a region of tissue and/or a catheter entrance site of
a patient using ultraviolet (UV) light. A region of tissue to be
sterilized or disinfected may include unbreached skin, such as a
region where a surgical incision is to be made, or breached skin,
such as a wound site or a catheter entrance site. In the case where
a catheter entrance site is being sterilized or disinfected, a
portion of the catheter in the vicinity of the entrance site may
also be sterilized. Another aspect of the invention is directed to
a method and apparatus for sterilizing or disinfecting a region of
tissue and/or a catheter entrance site of a patient using UV light
transmitted through a bandage.
[0029] It should be appreciated that while the terms "sterilize"
and "disinfect" are used generally herein, the methods and
apparatus described may be used to achieve a desired level (e.g.,
low or high) of sterilization or disinfection. The sterilization or
disinfection may occur by killing microorganisms, inactivating
microorganisms (i.e., rendering the microorganisms unable to
reproduce), or any combination thereof. It should further be
appreciated that, according to the present invention, a region of
tissue or a catheter entrance site to be sterilized or disinfected
may be that of either a person or an animal.
[0030] Sterilization or Disinfection of Tissue and/or an Inserted
Catheter
[0031] FIG. 1 illustrates a method for sterilizing or disinfecting
a region of skin or tissue of a patient using sterilizing or
disinfecting light, in accordance with one embodiment of the
invention. Sterilizing or disinfecting light is emitted by a light
source 7 and exposed to wound 1 and/or surrounding tissue 5. Tissue
5 includes skin 3 and tissue below the surface of skin 3. While
skin 3 is highly attenuating to sterilizing or disinfecting light,
some light may permeate to the tissue below skin 3, for example
exposing pores of skin 3. A reflector 9 is disposed near light
source 7 to aid in directing light emitted by light source 7
towards wound 1 and surrounding skin 3. While reflector 9 is shown
as disposed above light source 7, it may be located on either side
of the light source 7 or may be eliminated entirely. Further,
additional reflectors may be included around light source 7 in
accordance with the invention. Light source 7 may be any light
source that emits light capable of sterilization or disinfection.
For example, light source 7 may be an ultraviolet (UV) light source
such as a mercury vapor lamp, a xenon flash lamp, a continuous arc
lamp, UV light emitting diodes (LEDs), a UV laser, or any other
solid state or non-solid state UV light-emitting device. The lamp
may emit narrow spectrum light (e.g., a line spectrum) or broad
spectrum light. Broad spectrum light may include, e.g., UVA, UVB,
and UVC light, or UV light accompanied by light from another
portion of the electromagnetic spectrum. For example, the emission
of both UV and visible light from light source 7 may enhance the
effectiveness of the light source, as the sensitivity of different
microorganisms to light varies with the wavelength of the light. It
should be appreciated that though a single light source 7 is
described and illustrated, one or more light sources may be
used.
[0032] Light may be generated by light source 7 in one or more
flashes. If multiple flashes are generated, the flashes may be
applied at specified intervals that may occur, for example, one or
more times per day. A flash lamp or other non-continuous lamp may
be used to generate light in one or more flashes. The lamp may be a
high intensity source of sterilizing or disinfecting light where
the sterilization dosage may be applied in less than a few minutes
or seconds. The energy of a single flash may be sufficient to
deliver a sterilizing or disinfecting dosage, e.g., greater than 10
mJ/cm.sup.2 of UVC, to all surfaces to be sterilized or
disinfected.
[0033] Light may also be generated by light source 7 as continuous
radiation over a period of time. To generate continuous radiation,
a lower intensity source capable of emitting sterilizing or
disinfecting light continuously over a period of time may be used.
The intensity of the light emitted by light source 7 may be
adjusted for use on skin of varying sensitivity to ultraviolet
light. For example, the light emitted by light source 7 may be
controlled at a lower intensity if the sterilization of
disinfection method is performed on an infant, for whom a lower
intensity may be more appropriate.
[0034] Wound 1 may be a lesion, cut, abrasion, or sore sustained by
the patient. Alternatively, wound 1 may be an incision or puncture
created by a healthcare professional. The method described above
may also be applied to unbreached skin, in accordance with the
invention. For example, the method for sterilizing skin 3 and/or
tissue 5 of a patient using sterilizing or disinfecting light may
be used to sterilize or disinfect the skin at a penetration site
prior to a medical procedure that breaches the skin. Thus, the
method described in connection with FIG. 1 may be employed by
medical professionals prior to or after medical procedures that
breach the skin. The method may also be employed by consumers or
medical professionals to treat the skin after accidental breach of
the skin.
[0035] FIG. 2 illustrates a method for sterilizing an installed
catheter and/or surrounding skin of a patient using sterilizing or
disinfecting light. Sterilizing or disinfecting light is emitted by
a light source 7, which directs light towards an entrance site 11
of a catheter 15 and/or the catheter itself in the vicinity of
entrance site 11. Entrance site 11 includes the opening in skin 3
through which the catheter passes. Entrance site 11 may also
include skin 3 and tissue 5 surrounding the opening. Reflector 9
may have any of the configurations described in connection with
FIG. 1. Further, light source 7 may have any of the configurations
described in connection with FIG. 1, and may be operated in any of
the described modes.
[0036] As shown in FIG. 2, catheter 15 includes a hub 13 and a
connector 14. Hub 13, which is external to the patient, may be any
junction where two or more lumens, each having separate tubing,
merge into a single multi-lumen tube. Connector 14 may be a
mechanism for attaching and detaching catheter 15 from external
catheter equipment (e.g., a bag containing intravenous fluid). It
should be appreciated that the catheter illustrated in FIG. 2 is
just one example of a catheter that may be sterilized or
disinfected in accordance with the invention. As described herein,
a catheter may include any conduit through which fluids or
mechanical devices pass into or out of the body. For example, a
standard injection needle, a blood sample needle, a cannula, a
trocar sheath, an introducer, or a shunt may be considered a
catheter. A device that breaches the skin may also be considered a
catheter. For example, a heart catheter, an endoscope, or a
laparoscope may be considered a catheter. The catheter need not
pass through an opening in the skin; instead the catheter may pass
through a natural opening, as is the case with Foley catheters or
other urinary catheters. In the above cases, the catheter passes
through the body's natural barrier to microorganisms, and thus
renders it susceptible to infection.
[0037] Instantaneous Sterilization or Disinfection
[0038] FIGS. 3 and 4A-4E illustrate an instantaneous
sterilization/disinfection unit 16a adapted to generate one or more
light flashes, in accordance with one embodiment of the invention.
As shown in FIG. 3, a housing 17 encloses a flash light source 7a
and reflector 9. Reflector 9, disposed about flash light source 7a,
causes light emitted by flash light source 7a to be reflected at
range of angles, thereby minimizing shadowing of the skin under
catheter 15.
[0039] Flash light source 7a and reflector 9 are optionally
protected by a UV transmissive window or screen (not shown) in an
opening 26 at the bottom of the unit. The window may be made from
quartz, fused silica, a UV transmissive glass or a screen, or a
perforated sheet of metal or other material. In some applications,
it is desirable to limit the amount of UVA, UVB, visible, infrared
light, and/or portions of the UVC spectrum emitted, for example for
use on sensitive skin or on infants susceptible to sunburn or local
overheating. In this case, an optical filter may be incorporated
into the window or the light source envelope to absorb or block
undesired wavelengths. Alternatively, a dichroic mirror, which
passes, rather than reflects the undesired wavelengths, may be
used. A window or mirror may also include a textured surface or
other diffusing mechanism to alter the exit angle of light and
thereby reduce shadowing.
[0040] A light seal 19 is disposed around opening 26 in
instantaneous sterilization/disinfection unit 16a. When light seal
19 is pressed against a patient or an object, it creates a
substantially light-tight chamber to contain the light emitted by
flash light source 7a and prevent injury or discomfort to the user
or others nearby. Thus, the light emitted by flash light source 7a
is substantially confined to housing 17 and the region on the
patient surrounded by light seal 19. This region may include a
region of skin 3 or tissue 5 and a region of catheter 15 near
entrance site 11.
[0041] Light seal 19 may be formed from a complaint material. For
example, light seal 19 may be formed from a convoluted and/or
foamed opaque elastomeric material such as neoprene, natural
rubber, silicone rubber, or a thermoplastic elastomer (TPE). The
use of a compliant material allows a substantially light-tight
chamber to be formed when light seal 19 of instantaneous
sterilization/disinfection unit 16a is placed over an irregularly
shaped surface. For example, light seal 19 may conform to a body, a
bandage, tape, or a catheter and its components. In FIG. 3, a
portion of light seal 19 conforms to the shape of hub 13 of
catheter 15. The compliance of light seal 19 also allows
instantaneous sterilization/disinfection unit 16a to be placed over
catheter 15 for sterilization/disinfection without disconnecting
catheter 15 at connector 14 from external catheter equipment.
However, the external catheter equipment may be disconnected at
connector 14 to allow hub 13 and connector 14 of catheter 15 to fit
under instantaneous sterilization/disinfection unit 16a, within the
confines of light seal 19, during sterilization or
disinfection.
[0042] Instantaneous sterilization/disinfection unit 16a may be
used to sterilize or disinfect entrance site 11 prior to insertion
of catheter 15 to prevent the transport of microorganisms from skin
3 to tissue 5 during insertion of the catheter, or may be used
while catheter 15 is in place. Instantaneous
sterilization/disinfection unit 16a may also be used prior to
penetration of skin 3 at the location of entrance site 11.
Instantaneous sterilization/disinfection unit 16a may be used in
addition to, or instead of, chemical treatment of skin 3 with a
chemical sterilizer or disinfectant, e.g., prior to incision of
skin 3 at entrance site 11. Sterilization or disinfectant chemicals
may include germicidal or antiseptic chemicals such as alcohol,
iodine, or betadine.
[0043] Instantaneous sterilization/disinfection unit 16a may
contain safety interlock actuators 21 coupled to light seal 19 to
prevent accidental activation of flash light source 7a when the
unit is not properly positioned. Safety interlock actuators 21
detect the compression of light seal 19 at one or more locations
(e.g., six as shown in FIG. 4C) to verify that light seal 19 is
placed against a surface before flash light source 7a is allowed to
trigger. An alternate or additional safety interlock may be
included to prevent flash light source 7a from triggering unless
the interior of housing 17 contains substantially no light,
indicating that the light seal between the interior and exterior of
housing 17 is substantially complete. A photodetector (not shown)
in housing 17 may be used to detect the presence of light in
housing 17.
[0044] As noted previously, instantaneous
sterilization/disinfection unit 16a is adapted to generate light
flashes. To generate light flashes, light source 7 may be a xenon
flash lamp, and may be made with an envelope of quartz, fused
silica, or UV transparent glass to maximize the output of UV light
in the flash. Flash light source 7a may be driven with a high
current density, e.g., 3,000 to 6,000 amps/cm.sup.2, and a short
flash duration, e.g., less than 200 microseconds for a small flash
unit, for maximum UVC light production. The energy required by
flash light source 7a to generate a flash sufficient for
sterilization or disinfection is determined by the amount of area
to be illuminated, the minimum sterilizing light dosage desired,
the uniformity of the illumination, and the spectrum of flash light
source 7a. For example, a flash light source made from UV glass
used to illuminate 25 square centimeters (about 4 square inches)
produces a UVC energy intensity of about 20 mJ/cm.sup.2 and a total
flash input energy of about 20 joules. Flash light source 7a may
also generate UVA, UVB, infrared, and visible light.
[0045] Instantaneous sterilization/disinfection unit 16a includes a
circuit board 29 enclosed within housing 17. Circuit board 29 may
include a capacitor 31 for storing a charge used by flash light
source 7a to generate a flash, and circuitry to charge the
capacitor and control the charging and flashing. Circuit board 29
is also coupled to a power source and safety interlock circuitry to
prevent accidental triggering at inappropriate times. The circuitry
required to charge the capacitor and trigger the flash may be the
same as that used in typical photographic flash units, which is
well known in the industry. One example of circuitry that may be
included on circuit board 29 will be discussed in connection with
FIGS. 16 and 17.
[0046] Housing 17 includes a power switch 23 to initiate the
charging of capacitor 31. Power switch 23 may be a simple on-off
power switch or pushbutton to control the power to circuit board 29
to charge capacitor 31. Power switch 23 is coupled to a power
source, which is shown as batteries 33 in FIGS. 4A, 4B, and 4E.
Batteries advantageously allow instantaneous
sterilization/disinfection unit 16a to be portable and hand-held.
Further, the power requirement for a typical
sterilization/disinfection unit is such that several hundred of
more sterilization/disinfection operations may be performed using a
single set of batteries. However, external power from an AC power
source may also be used. Housing 17 also includes a trigger switch
27 to control activation of flash light source 7a when safety
interlock actuators, when present, are activated. Power switch 23
and/or trigger switch 27 may be manipulated manually (e.g., by
pressing a button), or may be coupled to one or more actuators 21
in light seal 19 to trigger upon depression of light seal 19. The
inclusion of power switch 23 and trigger switch 27 enhances the
safety of instantaneous sterilization/disinfection unit 16a and
reduces its power consumption. However, either of power switch 23
or trigger switch 27 may be eliminated, as they are not necessary
to the operation of the unit.
[0047] A UV dosage control mechanism may also be included to vary
the intensity of the UV light generated by flash light source 7a.
For example, the UV light intensity may be varied to compensate for
the application of UV light through a bandage, which will be
discussed in connection with FIG. 12, or to account for the
sensitivity of the patient's skin. The UV dosage control may be
continuously variable or variable in discrete steps determined by a
switch. The sterilizing light output is controlled by altering the
energy stored in capacitor 31 by changing the voltage to which
capacitor 31 is charged, or by switching one or more capacitors
into the circuit to change the total capacitance value.
[0048] A ready indicator 25, such as a light emitting diode (LED)
may be included on the external surface of housing 17 to alert an
operator when the charging of capacitor 31 is complete, and hence
when a flash may be generated by flash light source 7a. A second
indicator (not shown), or a color change or flashing of a light of
indicator 25, may be included to alert an operator that safety
interlock actuators 21 have been activated, and hence that
instantaneous sterilization/disinfection unit 16a unit may be
operated. A third indicator (not shown), or a change in color or
flashing of other indicators, may be used to indicate that a
successful flash has occurred.
[0049] Instantaneous sterilization/disinfection unit 16a, described
above, is just one exemplary apparatus for sterilizing or
disinfecting a catheter, a catheter entrance site, a wound, and/or
a region of skin using one or more light flashes. Those skilled in
the art will readily see many possible variations on the physical
configuration, electronic circuitry, and controls of instantaneous
sterilization/disinfection unit 16a described above, which are
intended to fall within the scope of the invention.
[0050] Continuous Process Sterilization or Disinfection
[0051] FIGS. 5A-5C illustrate a continuous process
sterilization/disinfect- ion unit 16b adapted to generate
continuous radiation for a period of time, in accordance with one
embodiment of the invention. Continuous process
sterilization/disinfection unit 16b operates on the same principles
as instantaneous sterilization/disinfection unit 16a, except that
light is generated by a continuous light source 7b at a lower
intensity and over a longer period of time.
[0052] As shown in FIG. 5A, continuous process
sterilization/disinfection unit 16b operates by positioning the
unit over catheter 15 near entrance site 11, such that it
illuminates entrance site 11 and surrounding skin 3 and/or tissue
5, as well as a portion of catheter 15 near entrance site 11.
Continuous process sterilization/disinfection unit 16b is
maintained in this position for a time sufficient to provide a
sterilizing or disinfecting dosage of UV light. The sterilization
may be completely continuous, or it may be intermittent and
repeated at regular intervals as desired.
[0053] For convenience, continuous process
sterilization/disinfection unit 16b may include a mechanism for
attaching the unit to a site to be sterilized/disinfected or a
location near to the site, although the unit may be hand-held. For
example, adhesive tape or straps with fasteners such as
hook-and-loop fasteners (i.e., Velcro) may be used. The straps with
fasteners may be looped around a portion of the body or fastened to
bandages, etc. that are already attached to the body. Housing 17
may include receptacles or fastening points for the straps.
Alternatively, adhesive tape, straps, or another attachment
mechanism may be used to attach continuous process
sterilization/disinfection unit 16b to catheter 15. Since the light
seal for continuous process sterilization/disinfectio- n unit 16b
is not critical, a primary advantage of attaching the unit is to
hold the unit in the proper position for sterilization or
disinfection.
[0054] If tape or bandages are used over entrance site 11, they may
be removed before sterilization or disinfection. If UV-transmissive
tape and bandages are used, they may be left in place with the
sterilization/disinfection unit placed over them, as will be
discussed in connection with FIG. 13. Continuous process
sterilization/disinfection unit 16b is designed to allow for its
use over catheter 15 without disconnecting the catheter from the
external circuit. Alternatively, the external catheter circuit may
be disconnected to allow hub 13 and connector 14 of catheter 15 to
fit beneath continuous process sterilization/disinfection unit
16b.
[0055] As shown, a housing 17 of continuous process
sterilization/disinfection unit 16b encloses continuous light
source 7b and reflector 9, and is coupled to a power cord 35.
Reflector 9 reflects light from continuous light source 7b to the
surfaces and objects to be sterilized or disinfected. Reflector 9
also serves to redirect the light so that it strikes the surfaces
and objects from a multitude of angles, thereby minimizing shadows
and providing more uniform illumination.
[0056] Because the overall power requirement for continuous process
sterilization/disinfection unit 16b tends to be higher than for
instantaneous sterilization/disinfection unit 16a, it is preferable
to power the unit using AC power transmitted via a power cord 35,
although in some applications batteries may be appropriate. To
minimize the size and weight of the unit when batteries are used,
it is preferable, but not necessary, to locate the batteries in a
remote location connected by a power cord. Operator controls, such
as an on-off switch and controls for a timer are preferably small
and light-weight enough to be included in housing 17, although they
may be remotely located at the other end of the power cord.
Further, in the example of FIGS. 5A-5C, continuous process
sterilization/disinfection unit 16b includes a base 36 rather than
a compliant light seal because the lower intensity of the light
generated by instantaneous sterilization/disinfection unit 16a does
not present as much of a safety concern, although precautions may
still be appropriate to minimize exposure of the eyes to the UV
light.
[0057] Because a lower intensity of sterilizing or disinfecting
light is required for continuous process sterilization/disinfection
unit 16b, as discussed above, continuous light source 7b may be a
standard germicidal mercury vapor lamp. These lamps produce most of
their energy at a wavelength of approximately 253.7 nanometers, in
the middle of the UVC sterilizing band. With a mercury vapor lamp,
continuous process sterilization/disinfection unit 16b may require
several minutes or more for sterilization or disinfection. Mercury
vapor lamps produce a small amount of energy at UV wavelengths
outside of the UVC band, as well as energy in the visible spectrum.
The intensity of UVA and UVB light produced by these lamps is low
and typically does not present a hazard for others nearby at the
dosage level required for periodic sterilizations or low-level,
longterm, continuous sterilization.
[0058] If the intensity of the UV light at skin 3 is low enough,
continuous light source 7b may be illuminated for long periods of
time (e.g., hours or days) without damage to skin 3. Commonly
available mercury vapor lamps typically produce an intensity
incompatible with continuous operation, unless the light level is
attenuated with an optical filter or the electrical drive to
continuous light source 7b is controlled to reduce the intensity of
the emitted light. A reduction in the intensity of the light output
may be accomplished by turning continuous light source 7b
alternately on and off. The alternation may be performed at a low
frequency (e.g., with a period of a few seconds or minutes), or at
a high frequency (e.g., with a period of less than a second). The
alternation may also be performed at a low (less than 50%) or high
(greater than 50%) duty cycle. The switching of power to continuous
light source 7b may be performed with an electronic circuit, a
mechanical timer, or electromechanically, all of which are well
known to those skilled in the art.
[0059] Alternatively, sterilization or disinfection operations may
be performed once a day or a few times a day, and continuous light
source 7b may be turned on for long enough to perform a complete
sterilization or disinfection operation for each instance. The
timing for each operation may be preformed by a standard timer or
with a light sensor that measures light exposure and turns
continuous light source 7b off when a desired dosage is reached.
Continuous process sterilization/disinfection unit 16b may also be
turned on and off manually by an operator.
[0060] A UV dosage control may be included in continuous process
sterilization/disinfection unit 16b, to compensate for the
application of UV light through a bandage, which will be discussed
in connection with FIG. 13, or to account for the sensitivity of
the patient's skin. The UV dosage control may be continuously
variable or variable in discrete steps determined by a switch. As
discussed above, the sterilizing light output is controlled by
altering the intensity of light emitted by continuous light source
7b, the duty cycle of continuous light source 7b, or the total
on-time for each sterilization or disinfection.
[0061] A UV transparent window (not shown), made of a material such
as quartz, fused silica, or UV transparent glass, may be included
at opening 26 to protect continuous light source 7b while allowing
light to reach the target surfaces. The window could include an
optical filter to alter the spectrum of the emitted light. This may
result in a spectrum having greater efficacy and/or less damaging
light. The window could also include a textured surface or other
diffusing mechanism to alter the exit angle of the emitted light
and thereby reduce shadowing of the targets.
[0062] The drive circuitry for continuous light source 7b of
continuous process sterilization/disinfection unit 16b is included
in housing 17. The circuitry is not shown here, as it is typically
the same as that used for standard visible fluorescent lamps and is
well known to those skilled in the art.
[0063] Continuous process sterilization/disinfection unit 16b,
described above, is just one exemplary apparatus for sterilizing or
disinfecting a catheter, a catheter entrance site, a wound, or a
region of skin using a continuous application of radiation. Those
skilled in the art will readily see many possible variations on the
physical configuration, electronic circuitry, and controls of
continuous process sterilization/disinfection unit 16b described
above, which are intended to fall within the scope of the
invention. For example, continuous light source 7 may be replaced
by a pulse light source that requires a number of pulses over a
period of time to provide the required dosage. Continuous light
source 7 may be replaced by a broad-spectrum light source to
provide other wavelengths of light along with UV light. Optical
filters or dichroic mirrors may be incorporated into continuous
process sterilization/disinfection unit 16b to alter the spectrum
of the outputted light by reducing the intensity of damaging
wavelengths of light.
[0064] Sterilization or Disinfection Using a Light Directing
Component
[0065] For complete sterilization of catheter 15 near entrance site
11, it is desirable for all points on catheter 15 near entrance
site 11 to be exposed to the appropriate dosage of sterilizing
light. Further, to prevent microorganisms from entering the body at
entrance site 11, it is desirable that entrance site 11 and
surrounding skin 3 be sterilized or disinfected. The shape of some
of the catheter components makes it difficult for light to reach
all points on the surface of catheter 15 and skin 3 near entrance
site 11, where the catheter is placed against the skin. The
catheter may create a partially shadowed area that receives less
light than other areas. The effects of shadowing may be mitigated
if the total dosage of sterilizing light is high enough. However, a
higher dosage requires a more powerful UV light source and/or a
greater exposure time, which may cause a greater UV exposure to the
skin than desired. Accordingly, in one embodiment of the invention,
the components of the catheter are shaped to reduce shadowing
and/or include light reflecting or refracting components to direct
light to areas that might otherwise be partially or fully
shadowed.
[0066] Referring again to FIG. 2, catheter 15 is shown illuminated
with light source 7. As shown, an area 38 of skin 3 under the
portion of catheter 15 is ordinarily not exposed to light from
light source 7 due to shadowing by catheter 15. Reflector 9 causes
light emitted by light source 7 to approach the target surfaces and
objects from a multitude of different angles. Thus, some light will
reach partially shadowed area 38, but the total intensity of the
light striking area 38 will be less than that of the surrounding
areas. Additional reflectors or diffusers may be used to further
increase the intensity of the light striking area 38.
[0067] FIG. 6B illustrates an example of how catheter components
may be shaped to direct light to partially shadowed area 38 for
more uniform light distribution. In this example, a reflective
surface 37 is included on a light directing component 41 to reflect
light from light source 7 to partially shadowed area 38. Light
directing component 41 may be the hub of catheter 15, as shown in
FIG. 6B, or may be an additional component, as will be described in
connection with FIG. 7A. Thus, light directing component 41 may be
an existing portion of catheter 15 or a component added to catheter
15. Reflective surface 37 may be a sloped and/or mirrored, as shown
in FIGS. 6A and 6B. Although a curved mirror is shown, one or more
planar mirrors or refractive optics such as a cylindrical lens made
of a UV transparent material, may be used to direct the light from
light source 7 to area 38 under catheter 15.
[0068] Tabs 39 may be provided on either side of light directing
component 41 to provide a mechanism for attaching light directing
component 41 to the patient. For example, tabs may be affixed to
tissue 5 using sutures or an adhesive. The upper surface of light
directing component 41 may be shaped in a smooth arch to provide a
better light seal with instantaneous sterilization/disinfection
unit 16a, as shown in FIGS. 7A, 7B, and 7C.
[0069] FIGS. 7A, 7B, and 7C illustrate light directing component 41
used with instantaneous sterilization/disinfection unit 16a. It
should be appreciated that while instantaneous
sterilization/disinfection unit 16a is illustrated, other
sterilization/disinfection devices such as continuous process
sterilization/disinfection unit 16b may alternatively be used in
this embodiment. In some catheter installations, hub 13 is not
positioned close enough to entrance site 11 for reflective surface
37 to perform the desired function of directing light to area 38 if
reflective surface 37 is attached to hub 13. Thus, in this
embodiment, light directing component 41 is separate from hub 13.
Lightdirecting component 14 may attach to tube 12 of catheter 15
and may be movable along tube 12 so that it may be positioned near
entrance site 11 after catheter 15 is installed. Further, light
directing component 41 may have adhesive to hold light directing
component 41 in place once it is positioned on skin 3. Preferably,
light directing component 41 holds tube 12 of catheter 15 slightly
above the surface of skin 3 to allow sterilizing light to reach the
skin under tube 12. FIGS. 7A, 7B, and 7C show catheter 15 passing
through a hole 40 in light directing component 41, but
alternatively the component could have a groove to accommodate tube
12 of catheter 15. Light directing component 41 may be molded from
plastic, an elastomer, or a photochromic plastic or elastomer.
Alternatively, light directing component 41 may include a
color-changing additive that changes color upon exposure to UV
light. A color-changing effect may provide verification to an
operator that the target site has been exposed to UV light.
[0070] Light directing component 41 may not include reflective
surface 37. In this case, the light directing component 41 may
still hold tube 12 of catheter 15 away from skin 3 to allow
sterilizing light to reach area 38. If the dispersion of the light
from instantaneous sterilization/disinfect- ion unit 16a is high
enough, partially shadowed area 38 may receive enough sterilizing
light from the unit without the use of a specific reflective
surface. As above, light directing component 41 without reflective
surface 37 may include photochromic indicators to indicate an
exposure to UV light.
[0071] Sterilization/disinfection units 16a and 16b are designed to
have a beneficial effect when used with the standard catheters and
installation techniques currently in common use. However,
alterations to the physical configuration of the catheter and the
positioning of external catheter components may improve the ease of
use and efficacy of sterilization/disinfection units 16. These
alterations include adding to or changing the shape of the external
catheter components to minimize shadowing and/or to enhance the
light seal of the sterilization/disinfect- ion unit, or adding
color-changing materials to indicate UV light exposure.
[0072] UV-Transmissive Bandage
[0073] The sterilization/disinfection units previously described
are also designed to have a beneficial effect when used on bare
skin, and they may be used with traditional bandages if the bandage
is temporarily removed for the exposure to the sterilizing light.
However, in accordance with an embodiment of the invention, the
method for sterilization or disinfection described herein may be
implemented with a UV-transmissive bandage in place over the region
to be sterilized/disinfected. The term bandage is intended to
include any dressing, medical tape, pad, gauze, film, ointment, or
paint-on wound covering, or any combination of features
thereof.
[0074] Bandages that transmit sterilizing or disinfecting light may
be made by choosing appropriate materials and configurations. For
example, materials that are typically considered opaque to UVC
light may transmit a significant percentage of UVC light when
fabricated as a thin film. For example, a thin film of polyethylene
(a common material used for medical applications) having a
thickness of 0.002 inches (0.05 mm) transmits up to 80% of
sterilizing light from a xenon flash having a wavelength in the
range of 220 to 310 nm. Even films up to 0.01 inches (0.25 mm)
thick may transmit over 50% of the sterilizing light. Adhesive
tapes including a structural film and adhesive with a total
thickness of 0.006 inches (0.15 mm) may have a transmission of
sterilizing light of greater than 60%. A typical eight-layer thick
medical gauze pad transmits about 30% of the sterilizing light.
[0075] Medical bandages for use with catheters often consist only
of a layer of visually transparent tape with a layer of adhesive
added. Many of the visually transparent films currently used are
nearly opaque to light with a wavelength shorter than 310 nm and
are unsuitable for UV light transmission. However, bandages may be
fabricated from a specific material in an appropriate thickness to
enhance UV transmission. For example, bandages fabricated from
hydrophilic polyurethane sheet material with a thickness of
approximately 0.001 inch (0.025 mm) and with a film of acrylic
based adhesive with a thickness of approximately 0.001 inch (0.025
mm), as described in U.S. Pat. No. 4,595,001, may have a
transmission of sterilizing light that is greater than 50%. This
transmissivity is acceptable for sterilization of disinfection
through the bandage. A bandage for use with a
sterilization/disinfection unit may be manufactured to have a known
and controlled transmissivity to UV light. Thus, the light output
of the sterilization/disinfection unit may be adjusted to deliver
the correct dosage of sterilizing light to the skin and catheter
components to be sterilized or disinfected.
[0076] FIG. 8 illustrates a first configuration of a bandage 51
designed for use with a sterilization/disinfection unit, as
described herein. As shown, bandage 51 has an adhesive 53 coupled
to the periphery of a film 55 of bandage 51. Adhesive 53 may
attenuate UV light and therefore reduce the amount of light that
reaches the skin. To minimize this attenuation, adhesive 53 in
bandage 51 of FIG. 8 is selectively applied such that the portion
of film 55 that is placed above the entrance site of the catheter
is free of adhesive 53. Adhesive 53 forms a seal around the
periphery of bandage 51, which will provide a barrier to microbes.
Since UV light applied to the bandage may pass through region 57 of
bandage 51, which does not contain adhesive 53, the UV transmission
characteristics of adhesive 53 are not critical and do not need to
be controlled in manufacture.
[0077] All of the bandages described herein may be enhanced with
additional features to facilitate their use with a
sterilization/disinfection unit. In one example, a radiant heat
attenuating material may be added to film 55 of bandage 51 to
attenuate any heat generated by the UV light source. In another
example, a color-changing material, such as a photochromic or
fluorescent ink or dye may be added to adhesive 53 or film 55 of
bandage 51. The color-changing material may change color or emit
light when exposed to UV light. Alternatively, the color-changing
material may change color or emit light when exposed to light from
another portion of the spectrum. A color change resulting from
light from another portion of the spectrum may still provide an
indication of UV light exposure if the proportion of UV light to
the light from the other portion of the spectrum is known.
[0078] Since color-changing material may absorb some of the UV
light applied, and therefore reduce UV transmission, color-changing
material may be included only in a portion or portions of bandage
51, as desired. For example, color-changing material may be applied
to adhesive 53 or film 55 discontinuously, e.g., in a pattern. The
pattern may be an array of lines, dots, or other small shapes, to
allow the UV light to sterilize or disinfect the areas between the
color-changing material. Alternatively, color-changing material may
be applied along the edge of bandage 51 so as to not interfere with
the application of UV light. In yet another alternative, for
bandages that are larger than the illuminated area of the
sterilization/disinfection unit, a small amount of color-changing
material may be added to the entire bandage. While the addition of
the color-changing material to the entire bandage may decrease the
UV light transmission of bandage 51 by a small amount, the bandage
will transmit a sufficient amount of UV light as long as the total
transmission of the bandage is known and the light output is
adjusted accordingly.
[0079] As discussed above, color-changing material may be added to
adhesive 53. For example, color-changing material may be included
in adhesive 53 to make adhesive-free region 57 more obvious and,
hence, easier to position. Another additive, other than a
color-changing material, may alternatively be included to achieve
easier positioning. Color-changing material may also be included in
adhesive 53 to indicate that a sterilization/disinfection operation
has successfully occurred.
[0080] Also as discussed above, color-changing material may be
added to film 55. For example, color-changing material may also be
included in or printed onto film 55 of bandage 51 to indicate a
region or level of exposure of bandage 51 to UV light. In another
example, color-changing material may be included in or printed onto
film 55 of bandage 51 in a meaningful pattern to convey
information. As shown in FIG. 8, color-changing material may be
printed to form a logo 58, or other word or icon, or a barcode 60.
Color-changing material may also be printed to provide additional
information or instructions to a user or indicate a manufacturer of
the product.
[0081] A color-changing material having a long time constant (i.e.,
a slow color response) may also be added to film 55 of bandage 51.
The relaxation time constant for the color-changing material may be
chosen to match the desired time between doses of UV light from a
sterilization/disinfection unit. For example, when exposed to a UV
light dose, the color-changing material may change to match a
background color, making the color-changing material nearly
invisible. As the color-changing material changes back to its
original color, the material becomes more visible. When a user is
able to detect the color-changing material, or a pattern formed by
the material, the user may determine that reapplication of UV light
is appropriate. Alternatively, an optical detection device (e.g., a
photodetector) may be included in a sterilization/disinfection unit
to detect a pattern or hue of the color-changing material, where a
hue detected may include a color, brightness, saturation, or
presence or absence of coloration of the color-changing material.
For example, a pattern of color-changing material may form barcode
60, detectable by an optical detection device. The
sterilization/disinfection unit may be designed to operate only
when the barcode, or other pattern or hue, is readable.
[0082] Sterilization/disinfection unit may include a sensor to
detect if it is being used on bare skin or a bandage. One way of
sensing the material is to measure the electrical conductivity of
its surface by making electrical connection with two or more
contact points of the surface and measuring the resistance between
the points. Human skin will typically have a resistance of less
than a few megaohms, whereas the materials used for a bandage will
typically be hundreds of times higher. The conductivity may also be
measured using capacitive coupling and an alternating current sense
signal to measure the coupling between the contact points. If a
sterilization/disinfection unit detects that it is applied to bare
skin, the output level of its light source may be adjusted to a
level appropriate for bare skin.
[0083] The bandage detection feature may be used alone, or in
combination with a feature that automatically detects and adjusts
the output of the light source for different bandage types. For
example, if the unit detects the presence of a bandage, a
photosensor or other sensor may be activated to detect a code that
appears on the bandage. The code may be, for example, a barcode
printed on the edge of the bandage. The barcode may indicate the UV
light transmission characteristics of the bandage so that the
sterilization/disinfection unit may adjust its output accordingly.
A sterilization/disinfection unit with this feature would need to
be positioned properly to be operated, which would encourage proper
use. The sterilization/disinfection unit may include operator
indicators to inform the operator when the unit is properly
positioned and the code may be read. Indicators may also be
provided to inform the operator as to what intensity is being
selected, or if more than one application is required for proper
sterilization or disinfection through the bandage. This feature may
be combined with the long time constant color-changing material
used for the barcode to prevent the application of UV light more
frequently than is required.
[0084] Bandages that include pads (like those sold commercially
under the tradename "Band-Aid," and larger varieties used in
professional medicine) may also be constructed in a manner that
allows sufficient sterilizing light transmission for use with a
sterilization/disinfection unit. The pad provides greater
flexibility, which results in more comfortable bandages and
improved adhesion to the body. The pad may be made from a foamed
polyethylene or similar material with significant transmission of
UV light. For best transmission of UV light, the material would not
have colorants added, but would be a clear or milky color. However,
colorants that do not significantly degrade the transmission of UV
light, versus visible light, may be used.
[0085] FIGS. 9A and 9B illustrate another configuration of a
bandage designed for use with a sterilization/disinfection unit, as
described herein. In this configuration, bandage 51 has a pad 59
coupled to film 55 of the bandage, and a pad liner 61 coupled to
pad 59. Pad 59 and pad liner 61 are sufficiently transmissive to UV
light. The adhesive on film 55 also preferably is sufficiently
transmissive to UV light in the thickness used. A variety of
adhesives meet this condition, including some currently used for
medical bandages and dressings. The adhesive on pad liner 61 holds
pad 59 in position and adheres film 55 to the user's skin.
[0086] For sufficient UV light transmission, pad 59 should be made
from an appropriate UV transmissive material and be made in an
appropriate thickness. The pads of typical prefabricated bandages
are in the range of 0.02 inch (0.5 mm) to 0.06 inch (1.5 mm) thick
and are fabricated of medical gauze or a non-woven (felt-like)
fabric. Some bandages include a perforated polymeric sheet liner on
the pad, as shown in FIG. 9B.
[0087] A UV transmissive bandage may be made with traditional
materials if no colorants are used in the film (as is typical). For
example, the pad may be made from 8 layers of medical gauze
(approximately 0.04 inch (1 mm) thick), and the pad liner may be
made from a 0.002 inch (0.05 mm) thick polyethylene sheet. In an
exemplary bandage, the film with adhesive may have a sterilizing
light transmission of 75%, the pad may have a sterilizing light
transmission of 30%, and the liner may have a sterilizing light
transmission of about 80%. This would result in a total sterilizing
light transmission of about 18%. Although a higher transmission of
sterilizing light is desirable, it is still possible to use a
bandage of this construction in connection with the sterilization
and disinfection methods described herein. Sterilizing or
disinfecting the surface of the skin through this bandage would
require a total sterilizing/disinfecting light dosage of about 5.5
times that required for bare skin.
[0088] One exemplary alternative for the bandage described above is
to substitute a foamed polyethylene pad for a gauze pad. A foamed
polyethylene pad with a thickness of 0.04 inch (1 mm) may have a
sterilizing light transmission of 70%. The foamed pad presents a
polymeric surface to the wound, so a pad liner is not required. A
bandage made in this configuration has a total sterilizing light
transmission of about 50%, requiring only twice the sterilizing
light intensity required by bare skin. This configuration has the
to advantage of requiring less energy from the
sterilization/disinfection unit, though there may be medical
reasons why a configuration with a fabric pad is preferable. Both
configurations may be used with an appropriately designed
sterilization/disinfection unit.
[0089] FIGS. 10A, 10B, and 10C illustrate a further configuration
of a bandage designed for use with a sterilization/disinfection
unit, as described herein. In this configuration, film 55 is used
in place of pad liner 61 of the configuration of FIG. 9B. Film 55
may be perforated at the position of pad 59 if it is desired for
fluids to flow into the pad. Pad 59 is attached to film 55 with a
movable fastening 63. The fastening may be an adhesive fastener or
hook and loop fasteners, commonly know as "Velcro." Pad 59 may be
completely removed or folded to one side. Thus, UV light from a
sterilization/disinfection unit may reach the skin of the user
without traversing pad 59. Since the UV transmission
characteristics of pad 59 are not critical in this configuration,
the pad thickness and material may be determined based on medical
considerations. Hence, thick gauze pads are possible. Further, in
this configuration, the underside of pad 59 may be sterilized or
disinfected when the pad is totally or partially disengaged from
film 55. Thus, pad 59 may be sterilized or disinfected during use
to created a sterile surface.
[0090] The materials and/or colorants used in the bandages
described herein may be chosen and positioned such that the
attenuation of the sterilizing light through the bandage is similar
for all portions of the bandage. This allows a sterilizing dose of
UV light to be applied to the bandage without having some areas of
the skin underneath the bandage overdosed, which could cause damage
to the skin. For example, to achieve uniform attenuation of the
sterilizing light, the section of film 55 of bandage 51 that does
not cover pad 59 may be made to provide greater attenuation of the
sterilizing light than film 55 covering pad 59 to compensate for
the extra attenuation of pad 59. The light attenuation of the film
may be controlled by printing film 55 with a colored ink or dye
that absorbs, blocks or reflects the sterilizing light.
Alternatively, the adhesive will normally provide some attenuation
to the sterilizing light and its thickness and/or composition may
be controlled so the attenuation matches that of the pad. If the
pad is as large or larger than the illuminated area of the wound
sterilizer/disinfector, then the UV transmission characteristics of
the adhesive tape beyond the extent of the pad may not be
relevant.
[0091] Since one of the side effects of the application of UV light
to the skin is a suntan, it may be desirable to fabricate the
bandage to make the tanned spot less obvious by feathering the
edges. This may be done by grading the UV transmissivity of the
bandage to successively lower values towards the edges of the
illuminated area. This would cause any suntan to have a gradual
edge, rather that a shape edge that would be more noticeable and
displeasing. The plastic film in the tape or bandage could also
include an additive that selectively absorbs or blocks the
transmission of some wavelengths of light to alter the spectrum of
light that reaches the skin to filter out harmful or undesired
wavelengths. This filter could also reduce the suntan effect.
[0092] The bandages described herein may be used for many different
professional and consumer health care applications. FIGS. 11A and
11B illustrate another configuration of a bandage designed for use
with a sterilization/disinfection unit, as described herein. The
bandage of this configuration is typically a larger bandage for use
in professional applications. Bandage 51 includes a substantially
square film 55 with a substantially square pad 59 attached thereto.
This configuration has the advantage that a secure airtight seal
may be formed on the complete periphery of bandage 51, which may
create a complete barrier to external infection by microorganisms.
Bandages with this property may be manufactured in a variety of
sizes and shapes for professional medical use, consumer use, and
veterinary medical use. Catheters and regions of skin may be
sterilized or disinfected with one of the described
sterilization/disinfection units before and/or after the bandage is
applied, and periodically with the bandage in place, either by
medical professionals or by consumers.
[0093] Sterilization or Disinfection Using a UV-Transmissive
Bandage
[0094] FIG. 12 illustrates the instantaneous
sterilization/disinfection unit 16a of FIGS. 3-4 used with a
UV-transmissive bandage 51. For illustrative purposes, bandage 51
is shown covering wound 1. However, bandage 51 may alternatively or
additionally cover a catheter, a catheter entrance site, or healthy
skin. FIG. 13 illustrates the continuous process
sterilization/disinfection unit 16b of FIGS. 5A, 5B, and 5C used
with bandage 51. Similarly, while bandage 51 is shown covering
wound 1, it may alternatively or additionally cover a catheter, a
catheter entrance site, or healthy skin. Bandage 51 of FIGS. 12 and
13 may include any of the features or materials described herein,
and is not limited to any of the particular configurations
described. As discussed, sterilization/disinfection units 16a and
16b may generate UV light at an intensity matched to the UV
transmissivity of bandage 51. The light intensity generated by
sterilization/disinfection units 16a and 16b may be variable by
means of a knob, switch, or other mechanism on the units. The UV
transmissivity of bandage 51 may be measured by a user or may be
indicated, e.g., on the bandage itself. An indication on bandage 51
may be detectable by a sensor, e.g., a photosensor, within
sterilization/disinfection units 16a and 16b. Color-changing
material coupled to the underside of bandage 51 may indicate an
absorption of UV light and, hence, a transmissivity of bandage
51.
[0095] Although it is not necessary, bandage 51 may form a seal to
prevent contamination of the bandaged site. For example, the
bandage may be formed of a continuous film that is impervious to
microorganisms, such as bacteria and viruses. Existing commercially
available bandages may have UV-transmissive properties, although
they are not intended to be used in sterilization or disinfection
operations that use ultraviolet light. Thus, this incidental
property of commercially available bandages makes them suitable for
use with the described sterilization/disinfection units 16a and
16b.
[0096] It is preferable to use bandages with controlled UV
transmission characteristics so as to achieve consistent results.
Bandages with controlled UV transmission characteristics may be
made using conventional manufacturing processes with additional
quality control of the materials and thickness used. As discussed
previously, additives may be used on or in the film, pad, or
adhesive of the bandage used with sterilization/disinfection units
16a and 16b to control UV transmission or block harmful or
undesirable wavelengths of light.
[0097] Sterilization or Disinfection Using a Light Directing
Component and a Bandage
[0098] FIGS. 14A, 14B, and 14C illustrate light directing component
41 and instantaneous sterilization/disinfection unit 16a of FIGS.
7A, 7B, and 7C used with bandage 51. It should be appreciated that
while instantaneous sterilization/disinfection unit 16a is
illustrated, other sterilization/disinfection devices such as
continuous process sterilization/disinfection unit 16b may
alternatively be used in this embodiment. When used with bandage
51, light directing component 41 may form an air seal with tube 12
of catheter 15 and bandage 51 to prevent contamination of entrance
site 11 by external microbes carried by air. Light directing
component 41 may assist in forming this air seal by providing a
smooth convex curved surface over catheter 15, as shown in FIG.
14C, to which bandage 51 is easily adhered. Without light directing
component 41, it would be difficult for bandage 51 to form a
complete seal between skin 3 and the underside of tube 12 of
catheter 15.
[0099] FIG. 14B illustrates a bandage 51 having a film 55 partially
coated with an adhesive 53. A region 57 of film 55 above catheter
entrance site 11 is not coated with adhesive 53. Region 57 without
adhesive 53 is used to secure catheter 15 while providing an
ability to sterilize or disinfect entrance site 11 and the
surrounding region by transmitting UV light through bandage 51. In
the example of FIG. 14B, region 57 without adhesive 53 is large
enough to allow the UV light to sterilize or disinfect an area
around entrance site 11 and allow the UV light to reach light
directing component 41 to assure proper illumination under tube 12
of catheter 15. Adhesive 53 forms a seal with skin 3 and light
directing component 41 to prevent entrance site 11 from being
infected from external microbes.
[0100] It should be appreciated that adhesive 53 need not be
applied to bandage 51 of FIG. 14B in the illustrated way, according
to the invention. For example, region 57, which does not contain
adhesive 53, may be larger or smaller, or shaped differently.
Further, region 57 may be eliminated altogether so that adhesive 53
is applied continuously, intermittently, in rows, in dots, or in
any other type of pattern.
[0101] To form a complete air seal, light directing component 41 is
designed to have intimate contact with tube 12 of catheter 15. This
may be achieved in a variety of ways, such as molding the light
directing component 41 from an elastomer so that it forms a tight
fit over tube 12, forming a groove in light directing component 41
that has a hinged or separate piece to fill at least part of the
groove, using a rigid light directing component 41 with an inserted
elastomeric seal, using the elastomeric properties of the catheter
15 to seal against a rigid light directing component 41, or forming
a seal with the addition of an adhesive material around tube 12 of
catheter 15.
[0102] Reflective surface 37 of light directing component 41 may be
a separate attached component or it may be integral with light
directing component 41. The light directing function of light
directing component 41 may be separated from the light and/or air
sealing function of light directing component 41 and one or more
separate components may be used. It should be appreciated that
while a number of example configurations are described to perform
the functions of light directing, light sealing and air sealing,
those skilled in the art will readily see a variety of other
configurations that may perform these function in various
combinations.
[0103] Because the underside of hub 13 and/or light-directing
component 41 is not exposed to light, it is not sterilized once in
position. However, is not necessary to repeatedly sterilize this
area as the skin under hub 13 and/or light directing component 41
is intact and provides an appropriate barrier to microorganisms.
Skin 3 and tube 12 of catheter 15 in the vicinity of entrance site
11 need to be periodically sterilized/disinfected to prevent
microorganisms from entering the body at entrance site 11. If the
area around entrance site 11 is periodically sterilized or
disinfected, and non-sterile objects or air do not come in contact
with this area, the body is protected from infection entering
through the entrance site 11.
[0104] Sterilization or Disinfection of a
Sterilization/Disinfection Unit
[0105] The sterilization/disinfection units described herein may be
used for multiple patients in a professional medical environment.
The sterilization/disinfection unit itself could become a vector to
transmit microorganisms for one patient to another. In particular,
a bottom surface 48 of light seal 19, which is not normally exposed
to UV light, may come in contact with a patient, a catheter, or a
bandage.
[0106] FIG. 15 illustrates an example embodiment of a
self-sterilizer attachment 42 for instantaneous
sterilization/disinfection unit 16a. Self-sterilizer attachment 42
includes a housing 43, into which instantaneous
sterilization/disinfection unit 16a may be placed. A light seal 47,
disposed on the inner rim of housing 43, forms a seal with
instantaneous sterilization/disinfection unit 16a when the unit is
positioned within housing 43. Light seal 47 may be compliant, and
substantially prevents light from escaping from housing 43 when
instantaneous sterilization/disinfection unit 16a is in use.
Self-sterilizer attachment 42 includes pins 45 at the base of
housing 43. Pins 45 may be UV-transmissive to allow the region on
light seal 19 that contacts the pins to be sterilized or
disinfected. When light seal 19 of instantaneous
sterilization/disinfection unit 16a contacts and/or depresses pins
19, safety interlock actuators in light seal 19 of instantaneous
sterilization/disinfection unit 16a are activated. The activation
may engage instantaneous sterilization/disinfection unit 16a in a
"ready mode," which allows an operator to trigger generation of
light by light source 7, e.g., by pressing a trigger switch on the
unit. Alternatively, activation of the actuators may automatically
cause instantaneous sterilization/disinfection unit 16a to emit
light.
[0107] Housing 43 includes one ore more reflective surfaces 49.
Reflective surfaces 49 direct light to bottom surface 48 of light
seal 19, the underside of unit 16a, and/or the exterior of housing
17 of unit 16a. Reflective surfaces 49 may be formed of aluminum,
mirrors, or another UV-light reflective surface. When light is
emitted by instantaneous sterilization/disinfection unit 16a,
reflective surfaces 49 direct light back towards the unit to cause
sterilization or disinfection of its surfaces. More than one flash
or dose may be applied for an increased UV light dosage to ensure
complete sterilization, as there are typically no objects present
within housing 43 that would be damaged by a higher exposure.
[0108] It should be appreciated that although instantaneous
sterilization/disinfection unit 16a is shown, self-sterilizer may
be used with any of the sterilization/disinfection units described
herein. Further, although self-sterilizer attachment 42 is shown as
an attachment to the sterilization/disinfection unit, alternatively
it may be integrated therewith. Although pins 45 are shown and
described as activating the actuators, a number of alternative
configurations may be used to perform the same function (e.g., a
light detector, a mechanical lever, a magnetic field detector, or a
pressure sensor).
[0109] Electrical Configuration of an Instantaneous
Sterilization/Disinfection Unit
[0110] According to one embodiment of the invention, electrical
circuitry associated with a flash lamp of an instantaneous
sterilization/disinfecti- on unit 16a may be implemented as shown
by electrical circuit 65 in FIG. 16. Electrical circuit 65 may be
used in a sterilization/disinfection unit according to any of the
embodiments described above. Electrical circuit 65 uses a high
voltage power supply 69 that contains a capacitor to store the
energy necessary to power a flash lamp 67. A power source 71, which
may be an AC line or a battery, typically supplies a voltage in the
range of 200V to 1000V depending characteristics of the flash lamp
used, although the voltage supplied may be smaller than 200V or
greater than 1000V. Small linear flash lamps typically operate with
voltages of 200V to 500V; small short-arc flash lamps may require
1000V or more. The voltage is selected based on the flash lamp
specifications: the total energy desired per flash and the maximum
flash current desired. A higher voltage will provide a higher flash
current for the same energy, resulting in a greater percentage of
the flash light output in the ultraviolet spectrum. The energy per
flash is determined by Equation 1:
E=1/2 CV.sup.2 [1]
[0111] where E is the energy per flash in Joules, C is the value of
the energy storage capacitor in Farads and V is the voltage in
volts. For a sterilizer/disinfector application, the selected
voltage should be as high as possible so that the flash lamp
produces the greatest amount of ultraviolet light. The value of the
capacitor is then chosen to provide the desired amount of energy
per flash. The energy required by the flash to perform the
sterilization/disinfection is determined by the amount of area to
be illuminated, the minimum sterilizing light dosage desired, the
uniformity of the illumination, and the spectrum of flash lamp 67.
For example, a flash lamp made from UV glass used to illuminate 25
square centimeters (about 4 square inches) produces a UVC energy
intensity of about 20 mJ/cm.sup.2 with a total flash input energy
of about 20 joules.
[0112] The sterilizer/disinfector circuitry also includes a flash
lamp trigger 73 which is very similar to the trigger circuit in a
camera flash. The flash lamp trigger provides a very high voltage
pulse, typically in the range of 4 kV to 15 kV depending on the
specifications of the flash lamp, to initiate the flash. According
to one embodiment of the sterilizer/disinfector, a charge storage
capacitor is kept charged to the appropriate voltage whenever the
unit is powered on. Safety interlock switch 75 may prevent
triggering of flash lamp 67 when the a light seal formed by
sterilization/disinfection unit 16a is incomplete. Thus, flash lamp
trigger 73 may be initiated when a trigger switch and a safety
interlock switch 75 have been activated. Alternatively, either
trigger switch (e.g., a pushbutton) or safety interlock switch 75
(e.g., mechanical actuators) may individually initiate flash lamp
trigger 73.
[0113] FIG. 17 shows one example of a typical battery powered xenon
flash lamp driver circuit with trigger circuitry for activating
flash lamp 67. Circuits of this nature are commonly used in camera
flash units. For simplicity, the diagram does not show the details
of an AC power supply or user indicators. A power transistor 77 and
its related components form a low voltage oscillator, typically in
the range of 15 to 20 kHz. Current from a high voltage transformer
79 passes through a high voltage diode 81 and charges an energy
storage capacitor 83 to a voltage that will drive flash lamp 67. A
resistor 85 charges a trigger capacitor 87 to the flash lamp
voltage. When a diac 92 and a safety interlock switch 93 are
turned-on, trigger capacitor 87 is discharged through a trigger
transformer 89 which creates a very high voltage pulse to a trigger
electrode 91 on flash lamp 67 This causes flash lamp 67 to flash
using the stored energy in energy storage capacitor 83.
[0114] It should be appreciated that the above-described circuitry
is merely intended to illustrate one possible implementation, and
many such circuits are possible and known in the art. For example,
there exists in the art many circuits for driving flash lamps that
may be suitably applied to the sterilizers/disinfectors described
herein. Thus, the invention is not limited in this respect.
[0115] Having described several embodiments of the invention in
detail, various modifications and improvements will readily occur
to those skilled in the art. Such modifications and improvements
are intended to be within the spirit and scope of the invention.
Accordingly, the foregoing description is by way of example only,
and is not intended as limiting. The invention is limited only as
defined by the following claims and equivalents thereto.
* * * * *