U.S. patent application number 11/743227 was filed with the patent office on 2007-11-08 for lumen sterilization device and method.
Invention is credited to Nancy S. Chu, Leslie A. Feldman, Henry K. Hui, Szu-Min Lin, Hans Strobel, Harold R. Williams, Su-Syin S. Wu.
Application Number | 20070258873 11/743227 |
Document ID | / |
Family ID | 27503241 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070258873 |
Kind Code |
A1 |
Wu; Su-Syin S. ; et
al. |
November 8, 2007 |
LUMEN STERILIZATION DEVICE AND METHOD
Abstract
Devices and methods for sterilizing lumens involve a booster
that is attached to the lumen. In preferred embodiments, the
contact area between the lumen and the booster enhances the
penetration of an antimicrobial agent to the contact area.
Inventors: |
Wu; Su-Syin S.; (Irvine,
CA) ; Williams; Harold R.; (San Clemente, CA)
; Chu; Nancy S.; (Laguna Niguel, CA) ; Strobel;
Hans; (Zurich, CH) ; Lin; Szu-Min; (Laguna
Hills, CA) ; Hui; Henry K.; (Laguna Niguel, CA)
; Feldman; Leslie A.; (Calabasas Hills, CA) |
Correspondence
Address: |
PHILIP S. JOHNSON;JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
27503241 |
Appl. No.: |
11/743227 |
Filed: |
May 2, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10160869 |
May 31, 2002 |
7229591 |
|
|
11743227 |
May 2, 2007 |
|
|
|
09746990 |
Dec 22, 2000 |
|
|
|
10160869 |
May 31, 2002 |
|
|
|
09384761 |
Aug 27, 1999 |
6187265 |
|
|
09746990 |
Dec 22, 2000 |
|
|
|
08992131 |
Dec 17, 1997 |
|
|
|
09384761 |
Aug 27, 1999 |
|
|
|
09472319 |
Dec 23, 1999 |
6451255 |
|
|
11743227 |
May 2, 2007 |
|
|
|
08915922 |
Aug 21, 1997 |
6066294 |
|
|
09472319 |
Dec 23, 1999 |
|
|
|
Current U.S.
Class: |
422/243 |
Current CPC
Class: |
A61L 2/186 20130101;
A61L 2202/24 20130101; A61L 2/208 20130101 |
Class at
Publication: |
422/243 |
International
Class: |
A61L 2/20 20060101
A61L002/20 |
Claims
1-10. (canceled)
11. A system for sterilizing a lumen, comprising: a vacuum chamber;
a pump to evacuate the chamber; a dry booster attachable to and
detachable from a lumen; and a source of germicide.
12. The system of claim 11, wherein the dry booster comprises an
adaptor and wherein the lumen contacts the adaptor in a contact
area.
13. The system of claim 12, wherein the adaptor is constructed from
a material, at least in the contact area, that is permeable to the
antimicrobial vapor or gas.
14. The system of claim 12, wherein the adaptor comprises a surface
that is textured or uneven in the contact area.
15. The system of claim 11, wherein the dry booster encloses an
internal volume that is greater than the internal volume of the
lumen.
16. The system of claim 11, wherein the dry booster comprises a
flow restrictor.
17. The system of claim 11, wherein the dry booster comprises a
check valve.
18-28. (canceled)
Description
RELATED APPLICATION INFORMATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 09/746,990, filed Dec. 22, 2000, which is a
continuation-in-part of U.S. application Ser. No. 09/384,761, filed
Aug. 27, 1999, now U.S. Pat. No. 6,187,265; which is a continuation
of U.S. application Ser. No. 08/992,131, filed Dec. 17, 1997, now
abandoned, all of which are hereby incorporated by reference in
their entireties. This application is also a continuation-in-part
of U.S. application Ser. No. 09,472,319, filed Dec. 23, 1999, which
is a continuation-in-part of U.S. application Ser. No. 08/915,922,
filed Aug. 21, 1997, now U.S. Pat. No. 6,066,294, all of which are
hereby incorporated by reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to the sterilization of medical
devices. In particular, this invention relates to systems, methods
and devices for sterilizing lumens.
[0004] 2. Description of the Related Art
[0005] Articles such as medical instruments are normally sterilized
before use. There are many methods of sterilizing medical
equipment, including heat treatment and chemical methods. Heat
sterilization is normally performed with steam. Some equipment
cannot withstand either the heat or the moisture from steam
treatment. As a result, chemical sterilization is now commonly
used.
[0006] Chemical sterilization uses a sterilizing fluid such as
hydrogen peroxide, ethylene oxide, chlorine dioxide, peracetic
acid, formaldehyde, or a combination thereof. A plasma may be
induced to enhance the sterilization process. Although chemical
sterilization is normally highly effective, it may not be as
effective with medical devices having long, narrow tubes, or
lumens. It is difficult for the sterilizing agent to completely
penetrate and sterilize these long narrow tubes. In order to
enhance the penetration of the sterilizing agent down the entire
length of the lumen, several methods and several forms of apparatus
have been developed to flow sterilizing agent through the length of
the lumen, enhancing the effectiveness of the sterilizing
treatment.
[0007] For example, U.S. Pat. Nos. 4,410,492 and 4,337,223 describe
an apparatus and a method for sterilizing lumens in which the lumen
is placed in a socket connected to a circulating pump. The pump
circulates the sterilizing gas through the lumen. Although the
method is effective in sterilizing the lumen, the commercial
apparatus uses ethylene oxide as a sterilant, and sterilization
requires times of about 2-3 hours. Ethylene oxide is toxic.
Additional aeration time is needed to remove the residual.
[0008] U.S. Pat. No. 5,580,530 describes a method for delivering
sterilizing agent through long, narrow lumens. The lumen is
inserted into an adaptor connected to a vessel containing hydrogen
peroxide. The vessel is called a booster. The lumen, adaptor, and
booster are placed in a sterilization chamber. When the
sterilization chamber is evacuated during the sterilization
procedure, the hydrogen peroxide in the booster vaporizes and
passes through the lumen, sterilizing the interior of the
lumen.
[0009] An apparatus and a method for delivering sterilizing agent
directly into long, narrow lumens is described in U.S. Pat. Nos.
4,943,414, 5,580,530 and 5,733,503. The lumen is inserted into an
adaptor connected to a small vessel containing hydrogen peroxide.
The adaptor and the vessel which contains the hydrogen peroxide are
called the booster. The lumen, vessel, and adaptor are placed into
a sterilization chamber. When the sterilization chamber is
evacuated, the hydrogen peroxide vaporizes and passes through the
lumen, providing the necessary hydrogen peroxide to the interior of
the lumen. Although effective, the method has some disadvantages.
First, in some forms of the apparatus, the booster must be
"activated" manually by piercing a septum to make the hydrogen
peroxide liquid accessible. Second, the booster is used only once
before it is discarded. Third, the product has a limited shelf
life. The storage and shipping conditions may affect the shelf life
of the product.
[0010] In each of these sterilization methods, the lumen is held by
a connecting device, a socket in the case of U.S. Pat. Nos.
4,410,492 and 4,337,223 or a truncated cone adaptor when using the
method of U.S. Pat. No. 5,580,530. In all of these methods, there
are areas of contact between the device and the lumen in the area
where the lumen attaches to the connecting device. It is difficult
for the sterilizing agent to penetrate into these contact areas.
There is a need for an apparatus and a method of enhancing the
penetration of sterilizing gas or vapor into these contact areas
more effectively to allay any potential concerns about incomplete
sterilization.
[0011] There are also contact areas between the parts of medical
devices having two or more pieces. It is difficult to sterilize the
contact areas between the parts which make up the medical device.
There is a need for a method and an apparatus for enhancing the
penetration of sterilant into the contact areas between the pieces
which make up the medical device.
[0012] There is also a need for a method of sterilizing lumens
which does not require the use of a booster with limited shelf
life. Further, there is a need for a method which utilizes an
apparatus which is reusable, to reduce costs.
SUMMARY OF THE INVENTION
[0013] In accordance with one aspect of the invention, an apparatus
for sterilizing a lumen comprises a booster and a connecting device
between the booster and the lumen, wherein the connecting device
comprises a silicone material. Preferably, the connecting device
comprises textured or uneven surfaces. In alternative preferred
embodiments, the booster comprises a vessel containing an
antimicrobial fluid, or the booster is a dry booster.
[0014] In accordance with another aspect of the invention, an
apparatus for sterilizing a lumen comprises a dry booster and a
connecting device between the dry booster and the lumen, wherein
the lumen contacts the connecting device at a contact area and
wherein the contact area is adapted to enhance penetration of an
antimicrobial vapor or gas to the contact area. Preferably, the
connecting device is constructed from a material, at least in the
contact area, that is permeable to the antimicrobial vapor or gas,
and/or the surface of the connecting device in the contact area is
textured or uneven. Preferably, the dry booster encloses an
internal volume that is greater than the internal volume of the
lumen. Preferably, the dry booster comprises a flow restrictor
and/or a check valve.
[0015] In accordance with another aspect of the invention, a system
for sterilizing a lumen comprises: a vacuum chamber; a pump to
evacuate the chamber; a dry booster attachable to and detachable
from a lumen; and a source of germicide. Preferably, the dry
booster comprises an adaptor that contacts the lumen in a contact
area; more preferably, the adaptor is constructed from a material,
at least in the contact area, that is permeable to a germicide.
Preferably, the adaptor comprises a surface that is textured or
uneven in the contact area. Preferably, the dry booster encloses an
internal volume that is greater than the internal volume of the
lumen. Preferably, the dry booster comprises a flow restrictor
and/or a check valve.
[0016] In accordance with another aspect of the invention, a method
for sterilizing a lumen comprises providing a dry booster, a
connecting device, and a lumen; connecting a first end of the lumen
to the dry booster with the connecting device, wherein the lumen
contacts the connecting device at a contact area; placing the dry
booster, the connecting device, and the lumen into a chamber,
wherein the chamber is at a pressure; introducing an antimicrobial
vapor or gas into the chamber; causing the antimicrobial vapor or
gas to penetrate the contact area and the lumen; and sterilizing
the lumen. Preferably, the connecting device, at least in the
contact area, is permeable to a germicide, and/or the surface of
the connecting device in the contact area is textured or uneven.
Preferably, the dry booster encloses an internal volume that is
greater than the internal volume of the lumen. In one embodiment,
the method further comprises reducing the pressure in the chamber,
thereby at least partially evacuating the dry booster. In another
embodiment, the method further comprises creating a higher pressure
outside the dry booster than inside the dry booster; and flowing
the antimicrobial vapor or gas from the chamber into the dry
booster through the lumen. In another embodiment, the method
further comprises reducing the pressure in the chamber after the
flowing of the antimicrobial vapor or gas from the chamber into the
dry booster through the lumen, thereby causing at least a portion
of the antimicrobial vapor or gas in the dry booster to flow from
the dry booster through the lumen and into the chamber.
[0017] In accordance with another aspect of the invention, an
apparatus for sterilizing a lumen comprises a booster and a
connecting device between the booster and the lumen, wherein the
lumen contacts the connecting device at a contact area and wherein
the connecting device comprises an uneven or textured surface in
the contact area. Preferably, the connecting device is constructed
from a material, at least in the contact area, that is permeable to
the antimicrobial vapor or gas. In alternative preferred
embodiments, the booster comprises a vessel containing an
antimicrobial fluid, or the booster is a dry booster.
[0018] These and other embodiments are described in greater detail
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective drawing of an assembled booster and
adaptor with a lumen inserted in the opening of the adaptor;
[0020] FIG. 2 is an exploded perspective drawing of the booster,
adaptor, and lumen of FIG. 1;
[0021] FIG. 3A is a sectional view of the adaptor and lumen,
showing how the lumen fits into the opening of the adaptor;
[0022] FIG. 3B is a sectional view of the adaptor and lumen, with
the lumen inserted into the opening of the adaptor;
[0023] FIG. 4 is a blow-up of FIG. 3B showing a sectional view of
the area of contact between the adaptor and the lumen, where the
flow of sterilant vapor through the textured area of the adaptor
and through the material of the adaptor is shown with arrows;
[0024] FIG. 5 is a schematic drawing of a pair of scissors having
contact areas between the two parts of the scissors;
[0025] FIG. 6A is a sectional view of the contact area of the
scissors of FIG. 5 with the scissors in a closed position, where
one of the pieces making up the scissors is textured, according to
an embodiment of the invention;
[0026] FIG. 6B is a sectional view of the contact area of the
scissors of FIG. 5 with the scissors in an open position, where one
of the pieces making up the scissors is textured, according to an
embodiment of the invention;
[0027] FIG. 7 is a schematic drawing of a pair of scissors having
contact areas between the two parts of the scissors;
[0028] FIG. 8A is a sectional view of the contact area of the
scissors of FIG. 7 with the scissors in a closed position, where
both pieces of the scissors are textured, according to an
embodiment of the invention;
[0029] FIG. 8B is a sectional view of the contact area of the
scissors of FIG. 7 with the scissors in an open position, where
both pieces of the scissors are textured, according to an
embodiment of the invention;
[0030] FIG. 8C is a sectional view of the contact area of the
scissors of FIG. 7 with the scissors in a closed position, where
both pieces of the scissors are textured, according to an
embodiment of the invention;
[0031] FIG. 8D is a sectional view of the contact area of the
scissors of FIG. 7 in an open position, where both pieces of the
scissors are textured, according to an embodiment of the
invention;
[0032] FIG. 9 is a perspective view of a contact area between two
parts of a medical device, where both parts are textured and where
the two parts are in a closed position;
[0033] FIG. 10 is a perspective view of a contact area between two
parts of a medical device, where both parts are textured and where
the two parts are in an open position;
[0034] FIG. 11 is a schematic drawing of a pair of scissors having
contact areas between the two parts of the scissors;
[0035] FIG. 12A is a perspective view of texturing according to an
embodiment of the invention, where the texturing is in the form of
projections placed randomly on the contact surface;
[0036] FIG. 12B is a perspective view texturing according to an
embodiment of the invention, where the texturing is in the form of
projections placed in rows on the contact surface; and
[0037] FIG. 12C is a perspective view of texturing according to an
embodiment of the invention, where the texturing is in the form of
grooves.
[0038] FIG. 13 is a schematic diagram of a lumen attached to an
adaptor which is connected to a vessel according to a preferred
embodiment of the invention.
[0039] FIG. 14 is a schematic diagram of a lumen attached to an
adaptor which is connected to a flow restrictor and a vessel
according to a preferred embodiment of the invention, where the
vessel has a check valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0040] The embodiments of the method and the apparatus of the
present invention relate to the sterilization, disinfection,
rinsing, drying, or cleaning of articles such as medical
instruments having contact surfaces. Although certain embodiments
of the apparatus and the method are discussed with the example of
sterilizing areas of contact between a lumen and an adaptor, the
apparatus and the method have broad applicability to a variety of
forms of apparatus and methods. For example, the embodiments of the
apparatus and the method of the present invention can be applied to
disinfection, rinsing, or cleaning as well as sterilization.
[0041] The embodiments of the method and the apparatus apply to any
situation in which there are contact areas between an article to be
sterilized, disinfected, rinsed, dried, or cleaned and a device,
part, adaptor, external housing, or connector. The embodiments of
the method and the apparatus also apply to medical devices having
two or more parts, where there are points of contact between the
two parts. The embodiments of the method and the apparatus can be
applied wherever contact areas exist on a device. The terms
"sterilize", "sterilant", and other forms of this word throughout
the specification and claims are to be construed broadly and are to
be understood to include disinfection and other antimicrobial
processes.
[0042] Embodiments of the method and the apparatus of the present
invention are applicable to, for example, sterilization, rinsing,
disinfection, drying, or cleaning of lumens or medical instruments
having one or more lumens. The term "instruments having one or more
lumens" as used herein applies to medical or surgical devices such
as endoscopes, catheters, tubing, or similar instruments or
articles having one or more internal lumens. In this embodiment of
the device and the method of the present invention, antimicrobial
fluid may be supplied directly to the lumen or interior of the tube
of the instrument during the sterilization process. In general, the
lumen is held by an adaptor which is connected to a source of
antimicrobial agent or germicide. There are contact surfaces
between the adaptor and the lumen.
[0043] To enhance the sterilization, rinsing, disinfection, or
cleaning of the contact surfaces, one or a combination of the
following properties may be utilized in the adaptor, medical
device, or connector design and material selection: first, applying
texture or uneven surfaces to the contact area so as to reduce
surface contact and enhance axial diffusion of sterilant; second,
constructing the adaptor, medical device, or connector, at least in
the contact area, from a material which has minimal chemical and
physical interaction with the sterilant; and third, using a
material of construction, at least in the contact area, which is
permeable to the sterilant so that the sterilizing agent can
penetrate the material, enhancing radial diffusion of the
sterilant.
[0044] The texture or uneven surfaces are designed so that more
sterilant, disinfectant, rinsing fluid, or cleaning fluid can flow
around the textured or the uneven surfaces on the adaptor or
connector than flows though the material of the adaptor or
connector.
[0045] FIGS. 1 and 2 illustrate an embodiment of an apparatus
suitable for use in an embodiment of sterilizing or disinfecting a
lumen. FIG. 1 shows the assembled apparatus, and FIG. 2 is an
exploded view, showing the various parts of the apparatus. A
booster 20 is attached to an adaptor 30. A lumen 50 is inserted
into an opening 32 of the adaptor 30. The opening 32 is normally of
slightly smaller diameter than the outer diameter of the lumen 50
so that there is a snug fit between the inside of the opening 32
and the outside of the lumen 50.
[0046] Two forms of the booster 20 are described in detail in col.
9 line 11 to col. 12, line 19 and FIGS. 5 to 13 of U.S. Pat. No.
5,580,530, hereby incorporated herein by reference in its entirety.
Briefly, the booster 20 includes a vessel for containing hydrogen
peroxide, a membrane wall capping the vessel containing the
hydrogen peroxide, and an opener with a hollow spike which is used
to breach the membrane wall, activating the booster so that the
hydrogen peroxide can escape from the vessel. One form of the
booster is shown as 100 on FIGS. 5 to 9 and an alternative form as
200 on FIGS. 10 and 11 of U.S. Pat. No. 5,580,530. Those skilled in
the art will appreciate that a booster need not contain hydrogen
peroxide and thus can be a dry booster, and that the adaptor
described hereinbelow can be used with the booster, whether or not
the booster contains an antimicrobial agent, e.g., hydrogen
peroxide. Those skilled in the art will also appreciate that the
booster and the adaptor can be parts of a single unit.
[0047] The adaptor 30 is shown in more detail in FIG. 3A herein.
The adaptor 30 includes a cylindrical tubular body 34, an inwardly
facing annular flange 36 for firmly attaching the cylindrical
tubular body 34 to the booster 20, a truncated cone 38, the opening
32, and texturing 40 on the contact surface of the truncated cone
38 surrounding the opening 32. The adaptor has one or a combination
of the following properties.
[0048] First, texturing can be added to the contact surface. The
texturing can take various forms such as ridges, concentric rings,
uneven surfaces, projections having equal heights, projections with
varying heights, etc. Whatever form of texturing is used, there can
be a plurality of the ridges, rings, or projections of equal or
varying heights. The height of the texturing varies and is
generally related to the viscosity of the antimicrobial or cleaning
fluid. The height of the texture varies from approximately 0.0001
millimeters to approximately 50 millimeters. The height of the
texture for an antimicrobial fluid which is a gas will generally be
less than for an antimicrobial fluid which is a liquid, because a
gas has a lower viscosity than a liquid. Although the height of the
texturing can be determined by one skilled in the art, in general,
a height of approximately 0.001 millimeters to approximately 5
millimeters is preferred for an antimicrobial agent which is a gas.
The height of the texturing for a gas is more preferably in the
range of approximately 0.01 millimeters to approximately 2.0
millimeter, and most preferably in the range of approximately 0.1
millimeters to approximately 1.0 millimeters. The height of the
texturing which is preferred for a liquid is normally in the range
of approximately 0.01 to approximately 5 millimeters, depending on
the viscosity of the liquid. The height of the texturing for a
liquid is more preferably in the range of approximately 0.1
millimeters to approximately 4 millimeters, and most preferably in
the range of approximately 0.2 to approximately 2 millimeters.
[0049] The texturing preferably extends to the inside of the
opening 32, so that the area directly facing the lumen 50 as well
as the outer surface of the truncated cone 38 surrounding the
opening 32 is textured. The portion of the truncated cone 38 which
is textured is preferably in the range of approximately 0.001 to 50
millimeters, more preferably in the range of approximately 0.01
millimeters to approximately 20 millimeters, and most preferably in
the range of approximately 0.1 millimeters to approximately 10
millimeters, radically extending from the edge of the opening 32.
The amount of the contact area to be covered with texture may
depend on the length of the occluded area. The total length of the
textured surface is preferably approximately 5 times the length of
the occluded area, more preferably approximately 3 times the length
of the occluded area, and most preferably approximately 1.5 times
the length of the occluded area. The inwardly facing annular flange
36 fits into a shallow annular groove on the booster 20 when the
adaptor 30 is fitted into place on the booster, firmly attaching
the adaptor 30 to the booster 20. Those of skill in the art will
appreciate that the dimensions of the truncated cone 38 and the
opening 32 can be varied to accommodate various types of
instruments to be sterilized.
[0050] Second, the material, at least in the contact area,
preferably is compatible with the sterilant or sterilization agent,
that is, has minimum chemical and physical interaction with the
sterilant or sterilizing agent. Chemical interaction includes
chemical reaction or catalytic decomposition of the sterilant.
Physical interaction includes absorption or adsorption of the
sterilant by the material. Third, the material, at least in the
contact area, can be permeable to the sterilant so that the
antimicrobial fluid can penetrate through the material.
[0051] Suitable materials for fabricating the adaptor, at least in
the contact area, can include, but are not limited to, polyolefins
(including thermoplastic elastomers), fluorinated and/or
chlorinated polyolefins (including thermoplastic elastomers),
fluorovinylidene, chlorovinylidene, liquid crystal polymers such as
wholly aromatic polyester or polyester-amide, silicone rubber,
fluorinated silicone rubber, or polyester. These materials can be
mixed with one or more fillers which have minimum chemical/physical
interactions with the chemical sterilant. Fillers can be added to
enhance mechanical, electrical, or thermomechanical properties.
[0052] The following procedure may be used when sterilizing
equipment with the booster 20 and the adaptor 30. An appropriately
sized adaptor 30 is selected for the particular lumen 50 or other
equipment to be sterilized. The adaptor 30 is attached to the
booster 20, and the lumen 50 or other instrument to be sterilized
is inserted into the opening 32. The booster 20 is activated by
puncturing the membrane wall, and the hydrogen peroxide or other
sterilizing agent is free to enter the adaptor 30 and the interior
of the lumen 50 or instrument. In general practice, the activated
booster 20, adaptor 30, and lumen 50 are placed into a
sterilization chamber, the chamber is sealed, and the chamber is
evacuated, preferably to a pressure of approximately 100 torr or
less, more preferably to a pressure of approximately 50 torr or
less, and most preferably to a pressure of approximately 10 torr or
less. An antimicrobial fluid is then injected into the chamber,
where it vaporizes and contacts the exposed surface of the
equipment. For example, in the case of a lumen, it will be apparent
from the foregoing to those skilled in the art that the lumen may
be sterilized by the passage of antimicrobial vapor or gas from the
chamber and through the lumen, and/or by the passage from a booster
attached to the lumen, through the lumen and into the chamber,
depending on the respective pressures in the booster and chamber.
In either case, sterilization in the contact area takes place.
Various factors known to those skilled in the art can be used to
enhance sterilization such as heat, plasma, or high frequency
radiation.
[0053] The hydrogen peroxide or other antimicrobial fluid in the
booster 20 volatilizes when the chamber is evacuated. The germicide
vapor enters the adaptor 30 and the lumen 50, sterilizing the
interior of the lumen. The exterior of the lumen is sterilized by
the antimicrobial agent which is injected into the chamber.
[0054] FIGS. 3A and 3B illustrate the use of the adaptor 30 with a
lumen 50. One skilled in the art can appreciate that the size of
the opening 32 on the adaptor 30 can be varied, depending on the
size of the lumen 50 or other equipment connected to the adaptor
30. The body of the adaptor 30 can have shapes other than a
cylinder, depending on the shape of the booster 20. For example, a
rectangular adaptor 30 would be used if the booster 20 were
rectangular. Similar modifications would be obvious to those
skilled in the art.
[0055] The adaptor 30 can have several features which make the
sterilization of the lumen 50 even more effective than previous
devices. Some of these features are illustrated in FIG. 4, which is
a blowup of FIG. 3B, showing the area of contact between the lumen
50 and the adaptor 30. First, the areas of contact between the
adaptor 30 and the lumen 50 or other medical device can be reduced
by using textured surfaces on the adaptor 30. Thus, the opening 32
and the part of the truncated cone 38 which contact the lumen 50
can be textured, as shown in FIG. 4. Only the tips of the texturing
devices remain as areas of contact between the adaptor 30 and the
lumen 50. The contact area is far less than if the texturing were
not present. In addition, there are small gaps between the ridges
or "bumps" of the texturing which create an uneven surface. The
uneven surface allows fluid penetration in both longitudinal and
transverse directions. Therefore, the antimicrobial agent, rinsing
fluid, or cleaning fluid can enter these gaps and reach areas which
would otherwise be inaccessible.
[0056] Finally, if the material used to construct the adaptor 30 is
permeable to the antimicrobial agent, typically hydrogen peroxide,
peracetic acid, or chlorine dioxide, further enhancement of the
sterilization effectiveness can be achieved. The antimicrobial
agent can penetrate the adaptor 30 to reach any areas of contact
between the adaptor 30 and the lumen 50 or other instrument which
remain after the contact areas are minimized through surface
texturing. FIG. 4 shows arrows illustrating the penetration of the
sterilant vapor to the contact areas both through the gaps between
the unevenness of the texturing and through the permeable material
from which the adaptor 30 can be fabricated.
[0057] The effectiveness of penetration of the antimicrobial agent
through the material of the adaptor 30 to the contact areas can be
even further enhanced by making the adaptor 30 thinner in the
contact areas than in the remainder of the adaptor 30. For example,
in FIGS. 3A and 4, the wall thickness of the truncated cone 38 of
the adaptor 30 decreases from the outer end 42 to the opening 32.
The portion of the truncated cone 38 which is in contact with the
lumen 50 is the thinnest part of the truncated cone 38, and the
antimicrobial agent can penetrate to the contact area between the
adaptor 30 and the lumen 50 more effectively than if the adaptor 30
in this area were thicker. Making the adaptor 30 thinner in the
contact areas than in the remainder of the adaptor 30 is a way to
further enhance the penetration of the antimicrobial agent through
the material of the adaptor 30 into the contact area. Although this
is a preferred embodiment, it is not a required feature.
[0058] By using one or a combination of these features in the
adaptor 30, the contact area can be adapted so that the
antimicrobial agent can penetrate the areas of contact between the
adaptor 30 and the lumen 50 more effectively than in previous
designs. These features include: applying texture or uneven
surfaces to the contact area so as to reduce surface contact and
enhance bidirectional diffusion of sterilant; using a material
which has minimal chemical and physical interaction with the
sterilant; and forming the adaptor 30 from a material that is
permeable to the sterilant so that the sterilizing agent can
penetrate the material.
[0059] The embodiments of the method and the apparatus of the
present invention can be used whenever there are areas of contact
between an article to be sterilized through sterilization and a
connecting device for the article. Often, the connecting device
will have an aperture through which the article is inserted. Those
skilled in the art will appreciate that the various adaptors
described herein are examples of connecting devices. There are
areas of contact between the aperture of the connecting device and
the article to be sterilized. The article to be sterilized can
include a lumen, rod, or other device. The methods of the present
invention can be used in the connecting device and/or the article
to be sterilized. These methods include the use of texturing on the
areas of the connecting device which contact the device to be
sterilized in order to reduce the contact area between the article
and the connecting device. Second, the connecting device can be
made of a material which is permeable to the antimicrobial agent so
that any remaining contact surfaces can be sterilized by
penetration of the antimicrobial agent through the material of the
adaptor. Those skilled in the art are aware that silicone is one of
the polymers which is most permeable to gases and vapors. Third,
the selected material can be a material which has minimal physical
and chemical interaction with the antimicrobial agent. Ways to
optimize these design modifications will be apparent to those
skilled in the art. Generally, the height of the texturing is
selected to match the viscosity of the sterilant or sterilizing
agent so that more sterilant or cleaning fluid flows around the
texturing than through the material of the adaptor, connector, or
device. The embodiments of the method and the apparatus are
applicable to sterilization, rinsing, disinfection, and cleaning of
devices with contact areas.
[0060] Embodiments of the method and the apparatus of the present
invention can also be used to enhance the penetration of
antimicrobial agents, disinfection fluids, rinsing fluids, or
cleaning fluids to contact areas within a medical device during
cleaning, rinsing, disinfecting, and sterilization processes. The
embodiments of the method and the apparatus have broad
applicability.
[0061] Often a medical device is made of two or more pieces. There
are likely to be contact areas between the pieces from which the
medical device is formed. FIG. 5 shows one example of a medical
device made up of two or more pieces and having contact areas, a
pair of scissors 60. The pair of scissors 60 is made up of two
cutting blades 64 joined at the center by a pin 68 which forms a
pivot point. The portion of the cutting blades 64 in the area of
the pin 68 form a contact area which is difficult to clean,
disinfect, rinse, or sterilize.
[0062] FIG. 6A shows a cross section of the two blades 64 and the
pin 68 of the scissors 60 of FIG. 5, where the pair of scissors 60
is in a closed position. In the embodiment shown in FIG. 6A, a
plurality of grooves 70 are present in the contact area around the
pin 68 in one of the blades 64. The grooves 70 allow cleaning
fluid, disinfecting fluid, rinsing fluid, or germicide to flow into
the contact area, cleaning, disinfecting, rinsing, or sterilizing
the contact area. FIG. 6B shows the two blades 64 of the scissors
60 in an open position. The contact area between the two blades 64
when the pair of scissors 60 is in the open position shown in FIG.
6B is less than the contact area between the two blades 64 when the
scissors 60 are in the closed position, as shown in FIG. 6A. The
grooves 70 allow cleaning fluid, disinfectant, rinsing fluid, or
sterilant to flow into the contact areas, whether the pair of
scissors 60 is in the open position or in the closed position.
Because the contact area of the pair of scissors 60 is reduced when
the pair is scissors 60 is in the open position, it is preferred
that the cleaning, disinfecting, rinsing, or sterilizing be
performed when the pair of scissors 60 is in the open position,
though the grooves 70 or other texturing devices in the contact
area increase the effectiveness of the cleaning, disinfecting,
rinsing, or sterilizing whether the pair of scissors 60 is in the
open position or in the closed position.
[0063] FIG. 8A shows a cross section of an embodiment of the
scissors 60 of FIG. 7 in which both blades 64 making up the
scissors 60 have a plurality of grooves 70 in the contact area in
the region of the pin 68 which joins the two blades 64 at a pivot
point. In FIG. 8A, the scissors 60 are in a closed position. FIG.
8B shows a cross section of the scissors 60 of FIG. 7 in an open
position. The amount of contact area between the blades 64 in the
open position shown in FIG. 8B is reduced from the contact area
between the blades 64 in the closed position shown in FIG. 8A.
Cleaning fluid, disinfectant, rinsing fluid, or germicide can flow
through the grooves 70 into the contact area, cleaning,
disinfecting, rinsing, or sterilizing the remaining contact
area.
[0064] In the embodiment shown in FIG. 8A, the grooves 70 in the
two blades 64 are in a staggered arrangement, that is, a point 72
of the groove 70 in an upper blade 64 is aligned with a valley 74
in a lower blade 64. As seen in FIG. 8A, there are no points of
contact between the top blade 64 and the bottom blade 64 in the
portion of blades 64 with grooves 70 when the blades 64 are in the
closed position in the embodiment where the grooves 70 in the two
blades 64 are in a staggered arrangement.
[0065] FIGS. 8C and 8D show an alternate embodiment of the scissors
60 in which the points 72 in the upper blade 64 are aligned with
the points 72 in the lower blade 64, and the valleys 74 in the
upper blade 64 are aligned with the valleys 74 in the lower blade
64.
[0066] FIGS. 9 and 10 show two alternative perspective views of the
blades 64 of the embodiments shown in FIGS. 8C and 8D. The points
72 of the grooves 70 in a the top blade 70 are aligned with the
points 72 of the grooves 70 in the bottom blade 70. In the closed
position shown in FIG. 9, the contact areas between the two blades
64 are a plurality of parallel lines formed by the contact between
the points 72 in the upper blade 64 and the points 72 in the lower
blade 64.
[0067] FIG. 10 shows the two blades 64 in an open position. When
the blades 64 are in the open position shown in FIG. 10, the areas
of contact between the points 72 of the grooves 70 in the top blade
64 and the points 72 of the grooves 70 on the lower blade 64 are a
plurality of points. The grooves 70 on the blades 64 thus greatly
reduce the amount of contact area between the two blades 64,
whether the blades 64 are in an open position or in a closed
position. Because the contact areas between the blades 64 are a
plurality of points when the blades 64 are in an open position
versus a series of lines when the blades 64 are in a closed
position, it is preferred that the blades 64 be in an open position
when the cleaning, disinfecting, rinsing, or sterilization is
performed. Regardless of whether the blades 64 are in an open
position or in a closed position, cleaning fluid, rinsing fluid,
disinfectant, or germicide can flow through the grooves 70 to
clean, rinse, disinfect, or sterilize the blades 64, even the
contact areas between the blades 64.
[0068] FIGS. 12A, 12B, and 12C show various embodiments of
texturing that may be used to reduce the contact area between two
or more parts of a medical device, for example the pair of scissors
60 shown in FIG. 11. In the embodiment shown in FIG. 12A, the
texturing on the contact surface is in the form of a plurality of
projections 78 in random positions on the contact surface. In the
embodiment shown in FIG. 12B, the texturing on the contact surface
is in the form of projections 78 aligned in regular rows on the
contact surface. In the embodiment shown in FIG. 12C, the texturing
on the contact surface is in the form of grooves 70. Although the
projections 78 and grooves 70 of FIGS. 12A, 12B, and 12C are shown
as having equal heights, in other embodiments, the projections 78
and grooves 70 can have unequal heights. Other forms of texturing
on the contact surfaces are suitable for use in the embodiments of
the apparatus and the method of the invention, and the embodiments
of texturing shown in FIGS. 12A, 12B and 12C are not meant to be
limiting.
[0069] In other embodiments, the plurality of projections 78 can
have the shapes of points, lines, or a combination of points and
lines. In some embodiments, the plurality of projections 78 can be
combinations of the random arrangement of projections 78 of FIG.
12A, the arrangement of projections 78 in rows of FIG. 12B, and/or
the grooves 70 of FIG. 12C.
[0070] The plurality of projections or texturing on the contact
areas between the two or more parts surfaces provide a pathway for
the cleaning fluid, rinsing fluid, scrubbing fluid, or germicide to
contact the contact surfaces. The projections 78 are adapted so
that when fluid is applied to the medical device, more fluid flows
around the projections or texturing than through the material of
which the medical device is made. The fluids can be liquid, vapor,
or gas.
[0071] When medical devices are made of two or more parts with
contact areas between the parts, the parts are often movable. As
shown in the example of the scissors 60 of FIGS. 5, 7, and 11, the
two parts are often movable around a pivot. The pivot in the
example of the scissors 60 of FIGS. 5, 7, and 11 is the pin 68.
[0072] The medical device with two or more parts can be made from a
variety of materials such as metal or nonmetals, including, but not
limited to, TEFLON.TM., a tradename for polytetrafluoroethylene,
nylon, a generic name for polyamide, polyolefins (including
polyethylene, polypropylene, and thermoplastic elastomers),
stainless steel, titanium alloy, aluminum alloy, nickel-chrome
alloy, liquid crystal polymer, polyester, silicon rubbers, and
styrenic thermoplastic, including thermoplastic elastomers.
Further, the materials from which the two or more parts are formed
need not be the same. For example, one part of the medical device
can be made of metal and another part from a non-metal.
[0073] The medical device with two or more parts can be disposable
or reusable. The contact areas on the medical device can be due to
a joint, a hinge, a box lock, or a mated surface. Devices with
hinged surfaces include scissors, forceps, and clips. Typical
medical devices with two or more parts having contact surfaces
include scissors, forceps, holders, hemostats, or rongeurs. The
embodiments of the apparatus and the method of the present
invention can also be applied to luer locks, connector housings, or
any connectors that join two devices, for example, venting caps for
flexible endoscopes or connectors on flexible endoscope heads for
all-channel irrigators.
[0074] Fluids which may be used with the embodiments of the
apparatus and the method of the invention include cleaning fluids,
rinsing fluids, scrubbing fluids, or germicides. The germicide may
be a liquid, a gas, or a vapor. The germicide can be a disinfectant
or a sterilant.
[0075] One or more of the pieces forming the medical device can
incorporate the features of the embodiments of the method or the
apparatus of the present invention to enhance the penetration of
the fluid to the contact areas. These features include the use of
texturing or uneven surfaces on one or more of the pieces forming
the medical device in the contact areas between the two or more
pieces. The texturing helps to reduce the contact area. between the
pieces forming the medical device. Second, one or more of the
pieces forming the medical device, at least in the contact area,
can be made of a material which is permeable to the antimicrobial
agent. Third, the material selected to form one or more of the
pieces forming the medical device, at least in the contact area,
can be a material which has minimal physical and chemical
interaction with the antimicrobial agent. Any one or a combination
of these features can be used to enhance the penetration of the
cleaning fluid, rinsing fluid, scrubbing fluid, disinfecting fluid,
or sterilizing fluid to the contact areas between the two or more
pieces forming a medical device.
[0076] The antimicrobials used with the embodiments of the method
and devices of the various embodiments of the present invention
include solutions of glutaraldehyde, hydrogen peroxide, chlorine
dioxide, peracetic acid, or other antimicrobials, either in a pure
form or in an inert medium. Although high concentrations of the
antimicrobial agents are more effective, material compatibility and
handling problems may arise at high concentrations.
[0077] When a medical device with two or more parts having
embodiments of the apparatus of the present invention is cleaned,
rinsed, scrubbed, disinfected, or sterilized with a liquid, the
medical device is contacted with the cleaning, rinsing, scrubbing,
disinfecting, or sterilizing liquid. Advantageously, the medical
device is contacted with the liquid in a vessel. If the contacting
is in a vessel, the liquid may be circulated in the vessel. The
cleaning, rinsing, scrubbing, disinfecting, or sterilizing liquid
penetrates to the contact areas of the medical device. More liquid
flows around the plurality of projections on the contact surface
than through the material of the medical device, thus cleaning,
rinsing, scrubbing, disinfecting, or sterilizing the medical device
and the contact areas between the two or more parts of the medical
device. The effectiveness of the cleaning, rinsing, scrubbing,
disinfecting, or sterilizing can be enhanced even further by moving
the two or more parts of the medical device during the cleaning,
rinsing, scrubbing, disinfecting, or sterilizing. Moving the parts
of the medical device changes the contact areas between the two or
more parts.
[0078] If the medical device with two or more parts having
embodiments of the apparatus of the present invention is to be
cleaned, rinsed, scrubbed, disinfected, or sterilized with a vapor
or gas, the medical device is placed in a chamber, the chamber is
sealed, and the cleaning, rinsing, scrubbing, disinfecting, or
sterilizing fluid is introduced into the chamber. The pressure in
the chamber may optionally be reduced to vaporize the fluid. More
fluid flows around the projections on the contact area than flows
though the material of the medical device to clean, rinse, scrub,
disinfect, or sterilize the contact area between the two or more
parts of the medical device. Contacting the medical device also
cleans, rinses, scrubs, disinfects, or sterilizes the remainder of
the medical device which does not have contact areas.
[0079] In a preferred embodiment, the method and device of the
present invention relate to the sterilization of articles, such as
medical devices containing long, narrow lumens, using a dry
booster. The medical devices are devices such as endoscopes,
catheters, tubing, or other instruments having lumens, where the
device is preferably sterilized before use. Typical applications
include surgery, medical applications, and the agricultural and
fermentation industries.
[0080] The preferred embodiment has particular advantage in
applications for sterilizing lumens having internal diameters of 3
mm or less or having a length of 27 cm or more, though the method
is also applicable to lumens having wider diameters or shorter
lengths. The germicides used with the method of the present
invention are varied. Suitable germicides include, without
limitation, glutaraldehyde, hydrogen peroxide, chlorine dioxide, or
ethylene oxide. Unlike the other methods which use boosters, the
germicide is not limited to being liquid at atmospheric pressure
and a vapor at the temperature and pressure utilized in the
sterilization process. Both vapor and liquid processes are
applicable to the embodiments of the present method utilizing a dry
booster. With the use of the device of the present invention,
antimicrobial vapor is drawn through the lumen or interior of the
tube of the instrument during the vapor sterilization process
without the need to supply a separate vial of liquid germicide on
the end of the lumen, as with the wet boosters previously used.
[0081] The procedure for vapor sterilization using a dry booster is
generally as follows. The article to be sterilized is placed into
the sterilization chamber, the chamber is sealed, and the chamber
is evacuated to a pressure of less than about 50 torr, more
preferably to 20 torr or less. An antimicrobial solution is then
injected into the chamber, where it vaporizes and contacts the
exposed surfaces of the article. The time necessary for total kill
of specific microbial agents varies with the type and concentration
of antimicrobials present and with the degree of exposure to the
microbial agent. Microbials in cracks, crevices, mating surfaces,
or diffusion restricted areas are somewhat protected from the
antimicrobial agent and require more time for total kill than
microbials on the external surface of the article. Heat or high
frequency radiation such as plasma may be used to increase the
effectiveness of the antimicrobial and its penetration into remote
areas of the instrument.
[0082] The device of the preferred embodiment comprises a vessel
and a means for connecting the vessel directly to the lumen or the
end of the tube of the article to be sterilized. Unlike the prior
vessels, the vessel of the dry booster of the present invention
does not contain antimicrobial solution. The prior boosters
contained antimicrobial liquid which vaporized when exposed to
vacuum. The antimicrobial vapor traveled from the vessel into the
lumen.
[0083] In the preferred embodiment, the vessel attached to the
lumen does not contain antimicrobial liquid. When the chamber is
evacuated, the vessel, the lumen, and the means for connecting the
vessel to the lumen are also at least partially evacuated. When
antimicrobial vapor is injected into the chamber, the antimicrobial
vapor is drawn into the lumen because of the vacuum from the large
evacuated volume of the vessel attached to the lumen. Those skilled
in the art will appreciate that injection of the antimicrobial
vapor is injected into the chamber causes the pressure in the
chamber to be higher than in the booster, thereby enhancing flow of
the antimicrobial vapor from the chamber into the dry booster
through the lumen. Unlike the prior boosters, the antimicrobial
vapor is drawn inward into the vessel from the sterilization
chamber rather than being drawn out of the vessel into the
sterilization chamber. Although in both cases, the antimicrobial
vapor is drawn through the lumen, with the dry booster of the
present invention, there is no need to have a vessel containing
antimicrobial liquid. Those skilled in the art will appreciate that
the pressure in the chamber can be reduced after the flowing of the
antimicrobial vapor or gas from the chamber in the dry booster
through the lumen (such as by venting the chamber to the
atmosphere), causing at least a portion of the antimicrobial vapor
or gas in the dry booster to flow from the dry booster through the
lumen and into the chamber.
[0084] A form of "dry booster" suitable for use in the method of
the present invention is shown in FIG. 13. A lumen 100 is attached
by a first end to an adaptor 200. The second end of the lumen is
open to the interior of the sterilization chamber. The adaptor 200
shown in FIG. 13 is described in U.S. Pat. No. 5,580,530, herein
incorporated by reference. The adaptor is shown as item 170 in FIG.
6 of U.S. Pat. No. 5,580,530. The adaptor 200 comprises a
cylindrical tubular body 220 formed of a soft thermoplastic
elastomer, such as Schafer, GmbH THEKA-FLEX, S 2030M or silicone.
Those skilled in the art will appreciate that the use of these
materials is not limited to the adaptor 200, and that other
connecting devices may also comprise these materials. For the
adaptor 200 in FIG. 13, a truncated cone 240 extends inwardly,
proximally, from a distal end 260 of the adaptor body and
terminates in a central opening 280. The lumen 100 is inserted into
the central opening 280 of the adaptor 200. The end of the adaptor
200 not having the truncated cone 240 is attached to a vial
300.
[0085] The vial 300 is a receptacle of any shape which encloses a
substantial empty volume. Although the vial 300 of FIG. 13 is a
cylinder, other shapes are suitable, including round, rectangular,
square, elliptical, or any other suitable shape. All that is
important is that the vial 300 and the adaptor 200 enclose a
substantial volume of space which can be evacuated when the vial
300 is attached to the adaptor 200 and the lumen 100.
[0086] Other forms of adaptor 200 and vial 300 are suitable for use
with the method of the invention, including the various adaptors
described herein. For example, those skilled in the art are aware
that silicone is one of the polymers which is most permeable to
gases and vapors, and thus also realize that an antimicrobial gas
or vapor can penetrate the contact area between the adaptor and
lumen when the adaptor, at least in the contact area, comprises a
material such as silicone. All that is necessary is that the
adaptor 200 provide a fluid link between the lumen 100 and the vial
300 and that the vial 300 and adaptor 200 enclose sufficient volume
relative to the volume of the lumen 100 to be sterilized. As will
be shown below, the required ratio of the volume of the vial 300
and adaptor 200 relative to the volume of the lumen 100 depend on
the process conditions in the sterilization. Some suitable forms of
adaptor 200 and vial 300 for use in the method of the present
invention are shown, for example, in FIGS. 1, 2, 2A, 3, and 3A of
U.S. Pat. No. 5,580,530. The embodiments of the adaptor shown in
U.S. Pat. No. 5,580,530 include an expandable sheath, a bushing
comprising a series of rings of inwardly extending plastic flaps, a
bushing with an aperture for attaching disposable cartridges, a
drawstring on a pouch, and a "zip-lock" closure on a pouch. These
forms of the adaptor 200 are illustrative only, and the method of
the invention is not limited to these forms of adaptor 200.
[0087] The vial 300 can comprise any three dimensional container
preferably of semi-rigid or rigid material, having an opening
therein. The vial 300 may be made of, e.g., polyethylene,
polypropylene, glass, or any other material which is compatible
with the antimicrobial vapor. In the embodiments shown in FIGS. 3
and 3A of U.S. Pat. No. 5,580,530, the vial 300 comprises a pouch.
In the embodiments shown in FIGS. 1 and 2A of U.S. Pat. No.
5,580,530, the vial 300 comprises a vial. Any shape of vial 300 may
be used in the method of the present invention. The major
restriction on the vial 300 is that the vial 300 and adaptor 200
together have a volume larger than the volume of the lumen 100.
Those skilled in the art will appreciate that, when the adaptor 200
is not present, the vial 300 should have an internal volume that is
greater than the internal volume of the lumen. The required ratio
of the volume of the vial 300 and adaptor 200 relative to the lumen
100 depend on the process conditions, and the required ratios will
be described in the Examples below.
[0088] Experiments were performed to compare the sterilization
efficiency with and without a dry booster. In both sets of
experiments, a biological indicator of 1.6.times.10.sup.6 Bacillus
stearothermophilus spores on a stainless steel wire was placed in
the center of a stainless steel lumen 100. For the experiments in
Example 1, both ends of the lumen 100 were left open. For the
experiments with the dry booster in Example 2, the apparatus shown
in FIG. 13 was used. A first end of the lumen 100 was attached to a
first end of the adaptor 200 described in FIG. 6 of U.S. Pat. No.
5,580,530. The second end of the adaptor 200 was attached to an
empty polyethylene scintillation vial 300 with 17 mm outside
diameter. Vials 300 having varying lengths were tested to provide a
range of volumes of adaptor 200 and vial 300 relative to the volume
of the lumen 100. The sterilization results for the lumen without
the dry booster are given in Example 1. The sterilization results
for the experiments when the dry booster was attached to the lumen
are given in Example 2.
EXAMPLE 1
Sterilization Results with No Dry Booster on the Lumen
[0089] In Example 1, biological indicators of 1.6.times.10.sup.6 B.
stearothermophilus spores were placed in the center of lumens of
various lengths. The lumens were placed in a 72.5-liter STERRAD 50
sterilizer with a standard STERRAD 50 load double wrapped with CSR
wraps. The chamber was evacuated to 0.4 torr, and 740 mg of 59
weight % hydrogen peroxide were injected for 5 minutes to provide 6
mg/L of hydrogen peroxide vapor in the chamber. After 5 minutes of
injection and diffusion, the chamber was vented to atmospheric
pressure, the lumens were removed, and the sterility results of the
biological indicators were determined. The results are shown in
Table 1 below. TABLE-US-00001 TABLE 1 Sterility Results From Tests
with No Dry Booster (No. of Positives/No. of Samples) Lumen Size
Sterility Results 1 mm .times. 250 mm 0/3 1 mm .times. 300 mm 0/3 1
mm .times. 350 mm 0/3 1 mm .times. 400 mm 1/2 1 mm .times. 450 mm
3/3 1 mm .times. 500 mm 2/2
[0090] As shown by the results in Table 1 above, under the test
conditions, the interiors of the 1 mm ID lumens longer than 350 mm
were not sterilized by exposure to hydrogen peroxide vapor.
[0091] In Example 2, a "dry booster" comprising an adaptor 200 and
a vial 300 containing no liquid sterilant was attached to one end
of the lumen 100. All of the other test conditions were the same as
in Example 1. The results in Example 2 demonstrate the improvement
in sterilization efficiency of the interiors of long lumens when
the "dry booster" according to an embodiment of the method of the
present invention was attached to the end of the lumen 100 to be
sterilized.
EXAMPLE 2
Sterilization of Lumens With A "Dry Booster"
[0092] In the experiments of Example 2, one end of an adaptor 200
as described in U.S. Pat. No. 5,580,530 was attached to an end of a
1 mm.times.400 mm stainless steel lumen to be sterilized. A
biological indicator as described in Example 1 was placed in the
center of each lumen. The second end of the adaptor 200 was
attached to a 17 mm ID polyethylene scintillation vial 300 having
varying lengths and therefore varying volumes, as shown in FIG. 13.
The lumens 100 with the attached boosters comprising an adaptor 200
and vial 300 were exposed to hydrogen peroxide vapor under the
conditions described in Example 1, the chamber was vented, and the
sterility tests were measured. The results are shown in Table 2
below. TABLE-US-00002 TABLE 2 Sterility Results From Tests with a
Dry Booster (No. of Positives/No. of Samples) Ratio of Dry Booster
Volume/Internal Volume of 1 mm .times. 400 mm Lumen Sterility
Results 20:1 0/3 15:1 0/3 14:1 0/3 13:1 0/3 12:1 0/3 11:1 1/3 10:1
1/3 5:1 1/2
[0093] A 1 mm.times.400 mm stainless steel lumen was chosen for the
tests in Example 2, because the 400 mm lumen was the shortest lumen
which was not sterilized without the need for a dry booster in
Example 1.
[0094] There are two conclusions which can be drawn from the
results shown in Table 2. First, use of a "dry booster" can enhance
the sterilization of the interior of lumens. The interior of the
1.times.400 mm lumen in Example 1 was not sterilized. By contrast,
the interior of the 1.times.400 mm lumen was sterilized in the
majority of the examples shown in Example 2, where a dry booster
was attached to the end of the 1.times.400 mm lumen.
[0095] Second, the interior of the 1.times.400 mm lumen was not
sterilized unless the ratio of the dry booster volume (the volume
of the adaptor 20 and the vial 30) was at least 12 times as large
as the internal volume of the 1 mm.times.400 mm stainless steel
lumen. In cases where the ratio of the volume was less than 12:1,
not all of the samples were sterilized. A volume of dry booster to
the volume of the lumen of 12:1 or more is therefore required for
the dry booster to be effective in enhancing the sterilization of
the interior of the lumen, under the conditions of Example 2.
[0096] The comparative results from Examples 1 and 2 demonstrate
the improvement in sterilization efficiency for long lumens when a
dry booster having a volume of 12 or more times the volume of the
lumen is attached to the end of the lumen to be sterilized and the
chamber was evacuated to a pressure of 0.4 torr before the hydrogen
peroxide was injected into the chamber.
[0097] A series of experiments were performed to determine the
sterilization efficiency at various initial vacuum pressures. The
length of time for which the vacuum was maintained before injection
of the hydrogen peroxide was also varied. The effects of pressure
and length of the evacuation time are shown in Example 3 below.
EXAMPLE 3
Effects of Varying Evacuation Pressure and Evacuation Time
[0098] A plurality of 1 mm.times.500 mm stainless steel lumens 100,
each containing a biological indicator, were placed in a 72.5 liter
sterilization chamber as in Example 1. Dry boosters having various
volumes were attached to the ends of certain of the lumens, as
shown in FIG. 13. The remainder of the lumens were placed into the
chamber without a dry booster. The chamber was evacuated to a
pressure of either 0.4 torr or 0.1 torr and was maintained at the
pressure of 0.4 torr or 0.1 torr for a time period of between 0 and
20 minutes, as noted in Table 3 below. A total of 740 mg of 59
weight % hydrogen peroxide was injected for 5 minutes to provide 6
mg/L of hydrogen peroxide vapor in the chamber. After 5 minutes of
injection and diffusion, the chamber was vented to atmospheric
pressure, the lumens were removed, and the sterility results of the
biological indicators were determined. The results are shown in
Table 3 below. TABLE-US-00003 TABLE 3 Dependence of Sterility
Results on Evacuation Pressure, Evacuation Time, Presence of a Dry
Booster, and Volume Ratio of Dry Booster to Lumen (No. of
Positives/No. of Samples) Sterility Results Evacuation Conditions
Volume Ratio of Dry Evacuation Evacuation No Booster to Lumen
Pressure Time Booster 10:1 5:1 3:1 0.4 torr 0 minutes 2/2 1/2 2/2
-- 0.4 torr 5 minutes 2/2 0/2 2/2 -- 0.1 torr 0 minutes 2/2 0/2 2/2
-- 0.1 torr 10 minutes 2/2 0/2 1/2 2/2 0.1 torr 20 minutes 1/2 --
0/2 0/2
[0099] There are several conclusions that can be drawn from the
data in Table 3. First, the sterilization efficiency of the lumen
improves with lower evacuation pressures and longer evacuation
times. For example, sterilization with a 10:1 booster was not
effective at 0.4 torr with no vacuum hold time. The sterilization
was effective when the vacuum was maintained at a pressure of 0.4
torr for 5 minutes, however. Similarly, sterilization with a 10:1
booster was not effective with a sterilization pressure of 0.4 torr
with no hold time, but the sterilization was effective at a
pressure of 0.1 torr with no hold time.
[0100] Second, the sterilization efficiency with a dry booster was
at least as high as with no dry booster in all cases.
[0101] Third, the sterilization efficiency improved with higher
ratios of dry booster volume: lumen volume. All but 1 of the
coupons were sterilized when a dry booster with 10 times the volume
of the lumen was used. The sterilization efficiency steadily
decreased as the ratio of the dry booster volume to the volume of
the lumen decreased from a ratio of 10:1 to 5:1 and even further
when the ratio decreased to 3:1.
[0102] Fourth, the ratio of the volume of the dry booster to volume
of the lumen required to sterilize the interior of the lumen can be
decreased by using lower evacuation pressures and longer evacuation
times. In Example 2, ratios of dry booster volume/lumen volume of
12:1 were required to sterilize the interior of the lumens with
evacuation pressures of 0.4 torr with no hold on the evacuation
time.
[0103] In Example 3, the interior of the lumens could be sterilized
when the volume of the dry booster (adaptor and vial):volume of
lumen was 5:1 or even 3:1 when the pressure was reduced to 0.1 torr
and the chamber was evacuated to 0.1 torr for 20 minutes.
Evacuating the chamber to lower pressures for longer times
therefore allows dry boosters with lower volumes relative to the
volume of the lumen to be effective in sterilizing the lumens.
[0104] It is believed that the reason that the sterilization
efficiency improves with longer evacuation times is because the
increased exposure time to the vacuum removes more moisture from
the lumen. When less moisture is present, more hydrogen peroxide
can be drawn into the dry booster through the lumen.
[0105] In Example 4 below, a 1 mm.times.2000 mm TEFLON.TM. lumen
was used rather than the 1 mm.times.500 mm stainless steel lumen of
Example 3. The dependence of sterilization efficiency with
evacuation pressure and evacuation time was studied. TABLE-US-00004
EXAMPLE 4 Dependence of Sterility Results on Evacuation Pressure,
Evacuation Time, Presence of a Dry Booster, and Volume Ratio of Dry
Booster to Lumen With a TEFLON .TM. Lumen (No. of Positives/No. of
Samples) Sterility Results Evacuation Conditions Volume Ratio of
Dry Evacuation Evacuation No Booster to Lumen Pressure Time Booster
3:1 2:1 1:1 0.4 torr 0 minutes 3/3 0/3 1/3 -- 0.1 torr 20 minutes
1/2 0/2 0/2 2/2
[0106] Even with a dry booster volume:lumen volume of 3:1, all of
the biological indicators in the 1 mm.times.2000 mm TEFLON.TM.
lumens were sterilized with evacuation pressures of 0.4 and 0.1
torr. By contrast, when a 1 mm.times.500 mm stainless steel lumen
was sterilized in Example 3, not all of the biological indicators
were sterilized even with dry booster having a volume 5 times
larger than the lumen. The stainless steel lumen was shorter than
the TEFLON.TM. lumen, and the dry booster in the stainless steel
lumen experiments had a higher volume relative to the volume of the
lumen. Both the shorter length of the stainless steel lumen and the
larger volume of the dry booster in the experiments in Example 2
should have improved the sterilization efficiency. Instead, the
sterilization efficiency with the longer TEFLON.TM. lumen and the
smaller dry booster of Example 4 was higher than with the stainless
steel lumen in Example 3.
[0107] Further, when the chamber was evacuated to 0.1 torr for 20
minutes, sterilization of the TEFLON.TM. lumen was effective even
when the ratio of the volume of the dry booster (adaptor 20 and
vial 30) relative to the lumen 10 was as low as 2:1.
[0108] It is believed that the improved sterilization efficiency
with the TEFLON.TM. lumen in Example 4 is due to the TEFLON.TM.
lumen being less reactive with the hydrogen peroxide vapor. The
comparative results of Examples 3 and 4 demonstrate that TEFLON.TM.
lumens are easier to sterilize than stainless steel lumens.
[0109] The results of Examples 1-4 demonstrate that use of the "dry
booster" can enhance the sterilization of the interior of lumens.
Further, the ratio of the volume of the "dry booster" relative to
the volume of the lumen required for sterilization of the interior
of the lumen varies depending on the process conditions and the
type of lumen to be sterilized. A volume ratio of 12:1 was required
with evacuation pressures of 0.4 torr with no hold time with a
stainless steel lumen, as shown in Example 2. When the pressure was
reduced to 0.1 torr and the evacuation time was increased to 20
minutes, a volume ratio of 3:1 was required, as shown in Example 3.
Sterilization of a TEFLON.TM. lumen at 0.1 torr and 20 minutes
evacuation time was effective with a dry booster volume:lumen
volume of 2:1, as shown in Example 4. The sterilization efficiency
with a "dry booster" therefore depends on both the process
conditions and the type of lumen to be sterilized. Plasma may
optionally be introduced to enhance the sterilization.
[0110] FIG. 14 shows an alternative form of the "dry booster" with
some enhancements over the "dry booster" of FIG. 13. The "dry
booster" of FIG. 14 comprises an adaptor 200 and a vial 300 as does
the "dry booster" of FIG. 13. The "dry booster" shown in FIG. 14
additionally comprises a flow restrictor 400 between the adaptor
200 and the vial 300. The flow restrictor 400 limits the flow of
the antimicrobial vapor through the lumen 100, helping to maintain
the pressure difference between the vial 300 and the lumen 100.
[0111] Further, the "dry booster" shown in FIG. 14 further
comprises a check valve 500 on the vial 300. The check valve 500
allows the gas inside the vial 300 to be released from the vial 400
directly into the sterilization chamber rather than having to be
evacuated through the lumen 100. The check valve 500 therefore
reduces the length of time required to evacuate the vial 300.
[0112] The embodiments of the dry booster and the methods of
sterilizing devices with the embodiments of the dry booster provide
enhanced methods of sterilizing the interior of lumens without the
need to attach boosters containing antimicrobial solutions.
[0113] The enhanced sterilization efficiency with the dry booster
is probably due to the internal volume of the dry booster and the
initial pressure difference between the inside and outside of the
dry booster. The volume and the pressure act as a driving force to
cause the flow of germicide into the booster through the lumen. The
dry booster can also be applied to a liquid phase process or a
process at a pressure higher than atmospheric pressure by creating
a higher pressure outside the booster than inside the booster. The
amount of germicide flow into the booster can be controlled by the
volume of the booster. The liquid, gas, or vapor process can be
enhanced by reducing the pressure in the booster and the lumen
before introducing the germicide.
[0114] Another aspect of the invention involves a system for
sterilizing a lumen, where the system includes a vacuum chamber, a
pump to evacuate the chamber, a dry booster, where the dry booster
is attachable to and detachable from the lumen, and a source of
germicide. Preferably, the dry booster comprises an adaptor that
contacts the lumen in a contact area. Preferably, the dry booster
encloses an internal volume that is greater than the internal
volume of the lumen. More preferably, the internal volume of the
dry booster is at least 2 times the volume of the lumen.
[0115] Various modifications and alterations of this invention will
be apparent to those skilled in the art without departing from the
scope and spirit of this invention. It should be understood that
the invention is not limited to the embodiments disclosed therein,
and that the claims should be interpreted as broadly as the prior
art allows.
* * * * *