Patent Description:
Medical devices are typically sterilized before use in order to minimize the likelihood that a contaminated device might be used on a subject, which could cause an infection in the subject. Various sterilization techniques may be employed, such as steam, hydrogen peroxide, and vapor phase sterilization, either with or without a gas plasma and ethylene oxide (EtO). Each of these methods depends to a certain extent on the diffusion rates of the sterilization fluids, typically gases, upon the medical devices to be sterilized.

Before sterilization, medical devices are typically packaged within containers or pouches having a semi-permeable barrier that allows transmission of the sterilizing fluid-sometimes referred to as a sterilant-but prevents admission of contaminating organisms, particularly post-sterilization and until the package is opened by medical personnel. For the sterilization cycle to be efficacious, the contaminating organisms within the package must be killed because any organisms that survive the sterilization cycle could multiply and recontaminate the medical device.

Although the packaging helps prevent contamination of a sterile medical device, the packaging may increase the difficulty of achieving a successful sterilization cycle because the packaging impedes the sterilant from reaching the device or instrument contained therein. This is particularly problematic for devices and instruments that have diffusion-restricted spaces therein because these diffusion-restricted spaces reduce the likelihood that a sterilization cycle may be effective. For example, endoscopes typically have long narrow lumens into which the sterilant must diffuse in sufficient concentration for sufficient time to achieve a successful sterilization cycle.

Confirming that a sterilization cycle has been efficacious helps medical personnel avoid using a contaminated medical device on a subject. Typically, the sterilized medical device is not itself checked for contaminating organisms because such an activity would introduce other contaminating organisms to the medical device, thereby re-contaminating it. Thus, an indirect check has been developed in the form of a sterilization indicator.

A sterilization indicator is a device that may be placed alongside or in proximity to a medical device being subject to a sterilization cycle, such that the sterilization indicator is subject to the same sterilization cycle as the medical device. For instance, a biological indictor having a predetermined quantity of microorganisms possessing known resistance to the sterilant may be placed into a sterilization chamber alongside a medical device and subjected to a sterilization cycle. After the cycle is complete, the microorganisms in the biological indicator may be cultured to determine whether any of the microorganisms survived the cycle.

Certain biological indicators are referred to as being "self-contained. " These biological indicators typically include a housing that contains a quantity of microorganisms and a source of growth media in a frangible container that is located near the microorganisms. Like other biological indicators, the "self-contained" biological indicator ("SCBI") may be subject to a sterilization cycle alongside medical devices. Following the cycle, the frangible container may be broken to release the growth media and culture any surviving microorganisms in situ. The SCBI may be incubated at elevated temperatures, typically around <NUM> to <NUM>, which encourages outgrowth of the surviving microorganisms. Incubation using commercially available products typically lasts for about twenty-four hours. During this time, while the effectiveness of the sterilization remains unconfirmed, it is desirable that medical personnel do not use the medical devices. This may cause inventory management inefficiencies for a health care provider, such as a hospital, because, for example, the medical devices should be stored while they cannot be used, perhaps requiring the health care provider to keep more medical devices in its inventory than it otherwise would to ensure a sufficient supply of medical devices. Alternatively, health care providers may use the medical devices before the incubation is completed and sterilization efficacy confirmed. However, using the medical devices before sterilization efficacy has been confirmed may expose a subject of a medical procedure to risk of infection from the medical devices.

After incubation, the SCBI is analyzed to detect the presence of microorganisms. Should any microorganisms be detected, some SCBIs are designed to incorporate a growth medium that changes color in the presence of microorganisms. If a color change is detected, the sterilization cycle may be considered to have been ineffective. Should no microorganisms be detected, the sterilization cycle may be considered to have been effective. This color change may be due to a shift in pH that occurs due to acid production by live microorganisms that metabolize a growth medium, which also contains a pH indicating dye. Other SCBIs are designed to incorporate a growth medium that includes a fluorophore whose fluorescence depends on the amount of viable microorganisms contained in the medium. For these SCBIs, a color change or change in the amount of fluorescence indicates that surviving microorganisms may have multiplied during incubation.

The frangible container of the SCBI that contains the liquid growth medium is often fabricated from glass. The glass must be sufficiently robust to avoid breakage during transportation, e.g., from the manufacturer of the SCBI to a health care provider. Such robustness, however, corresponds to a greater force required to break the ampule at the desired time by medical personnel. Accordingly, some SCBI manufacturers provide activation devices to hospital personnel to assist them in breaking the ampule. <CIT> relates to a biological sterilization indicator, BI, and a method of using same for assaying the lethality of a sterilization process. The BI can include a housing, which can include a first portion, and a second portion, which can be movable with respect to the first portion between a first and second position. The BI can further include a frangible container comprising a liquid. The BI can further include a spore reservoir and a projection positioned in the housing. The projection can be configured to fracture the container when the second portion of the housing is moved from the first position to the second position. The method can include maintaining a minimal cross-sectional area of space around the container when the second portion of the housing is in the first position, and fracturing the container in response to moving the second portion between the first and second positions. <CIT> relate a biological sterilization indicator, BI, and method of using same. The BI can include a housing, and a container positioned in the housing. The container can contain a liquid and at least a portion of the container can be frangible. The BI can further include a first chamber and a second chamber. The second chamber can include at least one source of biological activity. The BI can further include a first fluid path positioned to fluidly couple the first chamber and the second chamber, and a second fluid path positioned to allow displaced gas to move out of the second chamber. The method can include moving displaced gas out of the second chamber via the second fluid path as a sterilant is moved into the second chamber via the first fluid path and/or as the liquid is moved into the second chamber via the first fluid path. <CIT> relates to a device for opening an ampoule, said device comprising a substantially hollow cylindrical housing having an interior for accommodating an ampoule. The device also comprises a rotary element having a proximal section, to which a break-off section extending in the distal direction is connected. The break-off section is flexible in the radial direction and/or is pivotably connected to the proximal section in the radial direction. The rotary element can be rotated relative to the housing about the longitudinal axis in an actuating direction from an initial position to an intermediate position. ; In the area of the side wall, the housing has a first guiding structure, which is designed in such a way that the first guiding structure presses the break-off section inward during a rotation from the initial position to the intermediate position so that the break-off section exerts a radial shear force on the ampoule head of an ampoule accommodated in the interior in order to break the ampoule head off of the ampoule body. <CIT> relates to a biological indicator is made of a vial which contains a spore dot, a nutrient solution in a frangible ampoule, and means for positioning the spore dot and for breaking the ampoule to release the nutrient solution when the cap of the vial is fully pressed on. The nutrient solution may contain a pH indicator to determine whether all active spores on the strip were killed by a sterilization process which takes place prior to breaking the ampoule.

In a first aspect of the invention there is provided a self-contained biological sterilization indicator that includes a housing and an ampule disposed within the housing, the ampule having a first dome, a second dome and a sidewall. A cap is coupled to the housing. The cap includes a projection that is coupled to the ampule by a friction fit such that a central longitudinal axis of the ampule and a central longitudinal axis of the housing are aligned. An insert is disposed within the housing. The insert includes a well within which at least a portion of the bottom dome of the ampule is disposed. The insert also includes a ramp that is angled at least <NUM> degrees relative to the central longitudinal axis of the ampule and in contact with the second dome of the ampule, the ramp being configured to apply a first reaction force at the point of contact with the second dome of the ampule when a compressive force is applied between the cap and the housing along the direction of the central longitudinal axis of the housing. The insert also includes a stress concentrator disposed adjacent to the sidewall of the ampule, the stress concentrator being configured to apply a second reaction force against the sidewall of the ampule when the first reaction force is applied, thereby facilitating breakage of the ampule.

In some embodiments, the ramp and the stress concentrator are configured to restrict movement of the ampule away from the cap along the central longitudinal axis of the ampule. In some embodiments the stress concentrator has a pointed tip. In some embodiments the stress concentrator has a rounded tip. In some embodiments the stress concentrator may be disposed at least approximately <NUM> above the second dome. In some embodiments the stress concentrator may be disposed at least approximately <NUM> above the second dome. In some embodiments the stress concentrator spans an arc of at least approximately <NUM> degrees. In some embodiments the stress concentrator spans an arc of at least <NUM> degrees. In some embodiments the ramp spans an arc of at least approximately <NUM> degrees. In some embodiments the ramp spans an arc of at least approximately <NUM> degrees. In some embodiments the insert has a circular shape such that a midpoint of an arc spanned by the ramp and a midpoint of an arc spanned by the stress concentrator are collinear with a diameter of the insert. In some embodiments the ampule does not contact the housing. In some embodiments the stress concentrator contacts the sidewall of the ampule.

Also disclosed herein are steps that may be performed to activate the self-contained biological sterilization indicator. These steps include: a) generating a first reaction force between the second dome of the ampule and the ramp wherein a component of the first reaction force is directed transverse to a central longitudinal axis of the ampule; b) generating a second reaction force between the sidewall of the ampule and a tip of the stress concentrator in response to the component of the first reaction force; and c) breaking the ampule. The step of breaking the ampule may include initiating a crack at a point of contact between the stress concentrator and the sidewall of the ampule. Further, the first reaction force may be generated by applying a compressive force between the cap and the housing of the self-contained biological sterilization indicator.

The insert of the self-contained biological sterilization indicator may include no more than one stress concentrator. The angled surface of the self-contained biological sterilization indicator may be a feature of the insert. The insert may be disposed within the housing of the self-contained biological sterilization indicator. The ampule may rest upon the angled surface before the reaction force is generated. The cap may be coupled to the housing and it may also be coupled to the ampule by a friction fit. The ampule cannot contact the housing.

As used herein, the term "surface" should be understood as a feature of an object that forms a boundary of the object.

As used herein, the term "wall" should be understood as a feature of an object that forms at least a portion of a side, top, or bottom, of that object. A wall is an example of a surface.

As used herein, the term "insert" should be understood as an object that is disposed within a space or cavity defined by another object.

As used herein, the terms "arm," "finger," "leg," and "projection" should each be understood as an elongate member of an object that originates at and extends away from another feature of that object.

As used herein, the term "carrier" should be understood as an object upon which microorganisms and/or enzymes have been disposed.

As used herein, the term "reaction force" should be understood as a force generated by an object in response to another force on the object, where at least a component of the reaction force points in a direction opposite to the direction of the another force.

As used herein, the term "stress concentrator" should be understood as a feature that includes a surface area configured to exert a reaction force against an object, where the surface area configured to exert the reaction force is less than a surface area of the object upon which another force is exerted.

As used herein, the term "friction fit" should be understood as a coupled relationship between two or more surfaces that is achieved by friction.

While the specification concludes with claims which particularly point out and distinctly claim the subject matter described herein, it is believed the subject matter will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:.

The following description sets forth certain illustrative examples of the claimed subject matter. Other examples, features, aspects, embodiments, and advantages of the technology should become apparent to those skilled in the art from the following description. Accordingly, the drawings and descriptions should be regarded as illustrative in nature.

Referring to <FIG> and <FIG>, a self-contained biological indicator ("SCBI") <NUM> is shown. SCBI <NUM> includes a housing <NUM> and a cap <NUM> coupled thereto. Cap <NUM> includes a projection <NUM> that has a planar, angled, arcuate, annular, or conical shape, or some combination thereof. Cap <NUM> may further include a chemical indicator <NUM> that changes color when exposed to, e.g., a chemical sterilant such as hydrogen peroxide. Cap <NUM> may also include one or more through-holes <NUM>, to assist in the passage of gasses (e.g., air or sterilant) into or out from the SCBI. Cap <NUM> is coupled relative to housing <NUM> in a first position and is movable from the first position to a second position. In the first position (shown in <FIG> and <FIG>), Cap <NUM> is coupled to housing <NUM> in a manner in which gases (e.g., air or sterilant) may move from the surrounding environment and into the SCBI, or vice versa. In this position, any through-holes in cap <NUM> are disposed above housing <NUM> such that the inside of housing <NUM> is in fluid communication with the surrounding environment, which permits introduction and withdrawal of sterilant into and from SCBI <NUM>. Cap <NUM> may be depressed to move it into the second position relative to housing <NUM>. In this second position, through-holes <NUM> are disposed below a top end of housing <NUM>, which causes a tight fitting relationship between housing <NUM> and cap <NUM>, and blocks the through holes, effectively sealing off the inside of the SCBI <NUM> from the surrounding environment.

SCBI <NUM> also includes a source of microorganisms or active enzymes, such as carrier <NUM>, which is impregnated with bacterial spores, other forms of bacteria (e.g., vegetative), and/or active enzymes. Spores from Bacillus, Geobacillus, and Clostridia species are often used to monitor sterilization processes utilizing saturated steam, hydrogen peroxide, dry heat, gamma irradiation and ethylene oxide. Accordingly, carrier <NUM> may be impregnated with spores from Bacillus, Geobacillus, and/or Clostridia species. Carrier <NUM> may be water-absorbent and may be formed of filter paper. Sheet-like materials such as cloth, nonwoven polypropylene, rayon or nylon, and microporous polymeric materials may also be used. Non-water absorbent materials are also appropriate for use, such as metals (e.g., aluminum or stainless steel), glass (e.g., glass beads or glass fibers), porcelain, or plastic. Additionally, carrier <NUM> can be constructed of a combination of the aforementioned materials. In some embodiments, carrier <NUM> may have a thickness of approximately <NUM> to <NUM> millimeters.

SCBI <NUM> also includes an ampule <NUM>, having a first end <NUM>, a second end <NUM>, and a sidewall <NUM>. Sidewall <NUM> is substantially cylindrical and may have an elliptical or circular cross section. First end <NUM> and second end <NUM> dome are disposed at opposite ends of sidewall <NUM>, and may have the form of a hemiellipsoid or hemisphere. Accordingly, first end <NUM> may be referred to as first dome <NUM> and second end <NUM> may be referred to as second dome <NUM>. Ampule <NUM> contains a liquid growth medium. The growth medium should be capable of promoting growth of any viable microorganisms disposed on carrier <NUM>. Growth may be accelerated by incubation at elevated temperatures, e.g., between approximately <NUM> and <NUM>. Ampule <NUM> may be fabricated from a frangible or brittle material such as glass or plastic.

SCBI <NUM> may also include an insert <NUM>, which is shown in <FIG>. Insert <NUM> may include a platform <NUM> having a top surface <NUM> and a bottom surface <NUM>. Insert <NUM> also includes a sidewall <NUM>. Sidewall <NUM> of platform <NUM> may rest upon a support surface <NUM>, which may be integrally formed as part of housing <NUM>. Sidewall <NUM> and top surface <NUM> of platform <NUM> together define a well <NUM>, which is configured to receive second end <NUM> of ampule <NUM>. Platform <NUM> defines a bore <NUM> therethrough, through which the liquid growth medium may pass upon breakage of the ampule.

Insert <NUM> further includes a ramp <NUM>. Ramp <NUM> is disposed upon or formed as an integral feature of sidewall <NUM>. Ramp <NUM> includes an angled surface or ramp surface <NUM>. Ramp surface <NUM> and top surface <NUM> of platform <NUM> are disposed in an angular relationship. As shown in <FIG>, ramp surface <NUM> is disposed at θ degrees with respect to platform top surface <NUM>. θ may be equal to approximately <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, or less.

Insert <NUM> also includes a finger (arm) <NUM> that extends above well <NUM> of insert <NUM>. Finger <NUM> is disposed opposite ramp <NUM>. Disposed upon finger <NUM>, facing ramp <NUM>, is a stress concentrator <NUM>. Stress concentrator <NUM> may include a tip <NUM>. Tip <NUM> may be pointed. It may have a triangular configuration. Tip <NUM> may alternatively have a rounded configuration. Tip <NUM> is spaced a distance D above sidewall <NUM>. D may be equal to approximately between <NUM> and <NUM>, between approximately <NUM> and <NUM>, between approximately <NUM> and <NUM>, or it may be between approximately <NUM>-<NUM>.

Ramp <NUM> is disposed along sidewall <NUM> within well <NUM> while finger <NUM> extends upward from sidewall <NUM>. Accordingly, both ramp <NUM> and finger <NUM> may have arcuate configurations having curvatures similar to the curvature of sidewall <NUM>. In some embodiments, a midpoint of the arc of ramp <NUM> and a midpoint of the arc of finger <NUM> are collinear with a diameter of insert <NUM>. In some embodiments, the arc of ramp <NUM> spans at least approximately <NUM> degrees. In some embodiments, the arc of ramp <NUM> spans at least approximately <NUM> degrees. In some embodiments, the arc of finger <NUM> spans at least approximately <NUM> degrees. In some embodiments, the arc of finger <NUM> spans at least approximately <NUM> degrees.

Insert <NUM> may also include a leg (or legs) <NUM> that originates from bottom surface <NUM> of platform <NUM> and extends away therefrom. Leg <NUM> has a maximum length equal to the distance between support surface <NUM> and a bottom wall <NUM> of housing <NUM>. As shown in <FIG>, leg <NUM> has a length that is somewhat less than the distance between support surface128 and bottom wall <NUM>. Leg <NUM> may have a length that is approximately <NUM> to <NUM> millimeter less than the distance between support surface <NUM> and bottom wall <NUM>. Insert <NUM> may include multiple instances of leg <NUM>. For example, insert <NUM> may include three instances of leg <NUM>. Leg or legs <NUM> function to maintain carrier <NUM> against bottom wall <NUM> to help prevent carrier <NUM> from becoming damaged or dislodged during transportation.

SCBI <NUM> may be assembled according to the following steps. First, housing <NUM> is provided. Second, carrier <NUM> is placed into housing <NUM> such that it rests upon bottom wall <NUM> of housing <NUM>. Third, insert <NUM> is placed into housing <NUM> such that sidewall <NUM> of platform <NUM> rests upon support surface <NUM>. Alternatively, not shown, in some configurations lacking a support surface <NUM>, insert <NUM> may rest directly upon bottom wall <NUM> and may be in at least partial contact with carrier <NUM>. Fourth, ampule <NUM> is inserted into housing <NUM> such that second end <NUM> contacts ramp <NUM>. Finally, cap <NUM> is coupled to housing <NUM> and ampule <NUM>. Projection <NUM> has approximately the same diameter as ampule <NUM> such that a friction fit is formed between ampule <NUM> and projection <NUM>. So assembled, central longitudinal axes of ampule <NUM>, housing <NUM>, cap <NUM>, and insert <NUM> are coaxial or substantially coaxial. Other assembly procedures may be performed to achieve the same configuration of SCBI <NUM>.

The configuration of SCBI <NUM>, and in particular, the relationships between its various components, maintain ampule <NUM> in a stationary state, which helps prevent premature breakage of ampule <NUM>, e.g., during transportation from a manufacturing facility to a healthcare facility. For example, cap <NUM>, ramp <NUM> and stress concentrator <NUM> prevent ampule <NUM> from moving away from cap <NUM> or moving in a lateral direction within housing <NUM>. In some configurations, ampule <NUM> may contact tip <NUM>. In other configurations, there may be spacing between ampule <NUM> and tip <NUM>.

Because the central longitudinal axes of ampule <NUM> and insert <NUM> are coaxial, ramp <NUM> is disposed at an angle ϕ to ampule <NUM> where ϕ equals <NUM> degrees minus θ. Accordingly, ϕ may be equal to approximately <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, or more.

Following a sterilization procedure, an SCBI may be activated and monitored to determine whether a sterilization cycle was effective. To activate SCBI <NUM>, a compressive force <NUM> is applied between housing <NUM> and cap <NUM>. This compressive force is resisted by ampule <NUM> because ampule <NUM> is in contact with ramp <NUM> of insert <NUM> and insert <NUM> is in contact with, e.g., support <NUM> of housing <NUM>. When the compressive force applied to cap <NUM> is greater than a breakage force ampule <NUM> can withstand, ampule <NUM> will break. Once ampule <NUM> is broken, cap <NUM> moves to its second position and growth medium is released to immerse carrier <NUM>.

The specific breakage mechanism of ampule <NUM> provided by SCBI <NUM> lowers the magnitude of the compressive force that must be applied to cap <NUM> to break ampule <NUM>. Specifically, the compressive downward force applied to cap <NUM> causes a first reaction force at the point of contact between second end <NUM> of ampule <NUM> and ramp <NUM> of insert <NUM>. This reaction force is perpendicular to ramp surface <NUM>. Accordingly, this reaction force includes a component that is substantially parallel to the central longitudinal axis of ampule <NUM> and a component that is substantially perpendicular or transverse to the central longitudinal axis of ampule <NUM>. The transverse component causes sidewall <NUM> of ampule <NUM> to press against stress concentrator <NUM>, or more specifically tip <NUM> of stress concentrator <NUM>, which causes a second reaction force against sidewall <NUM> that is transverse to the central longitudinal axis of ampule <NUM>. The magnitude of this reaction force may be approximated as the magnitude of the force applied to the cap multiplied by tan(cp). As the magnitude of the compressive force applied to cap <NUM> increases, so too does the magnitude of the first reaction force and the second reaction force until the second reaction force becomes greater than the ampule can withstand, which causes the ampule to break. Because the second reaction force is applied laterally to sidewall <NUM>, the breakage is initiated at the point of contact between stress concentrator <NUM> and sidewall <NUM>. Initial cracks may be formed at or near this point of contact before the ampule breaks. When ampule <NUM> is fabricated from glass, formation of the initial crack or cracks is promptly followed by the glass shattering into many shards. These shards collect upon insert <NUM>, allowing the growth medium to flow through and alongside insert <NUM> to immerse carrier <NUM>.

Before activation of SCBI <NUM>, first end <NUM> of ampule <NUM> is maintained within projection <NUM> of cap <NUM> and second end <NUM> of ampule <NUM> is maintained within well <NUM>, between ramp <NUM> and stress concentrator <NUM>. This configuration has two beneficial purposes. First, this configuration minimizes the magnitude of the compressive force that must be applied to the cap to break the ampule because the compressive force presses ampule <NUM> against ramp <NUM>, which removes the collinear relationship between the longitudinal axis of ampule <NUM> and the longitudinal axis of insert <NUM>. Accordingly, stress concentrator <NUM> presses against sidewall <NUM> in an asymmetric manner, which increases the stresses in ampule <NUM>, in part by avoiding generation of internal stresses that cancel each other, thereby facilitating breakage of ampule <NUM>. Second, this configuration restricts movement of the ampule within the SCBI, which minimizes rattling and jostling of ampule <NUM> within SCBI <NUM> and helps avoid premature breakage of the ampule, e.g., during transportation.

It should be understood that any of the examples and/or embodiments described herein may include various other features in addition to or in lieu of those described above. The teachings, expressions, embodiments, examples, etc. described herein should not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined should be readily apparent to those of ordinary skill in the art in view of the teachings herein.

Claim 1:
A self-contained biological sterilization indicator (<NUM>) comprising:
(a) a housing (<NUM>);
(b) an ampule (<NUM>) disposed within the housing, the ampule having a first dome (<NUM>), a second dome (<NUM>), and a sidewall (<NUM>);
(c) a cap (<NUM>) coupled to the housing, the cap having a projection (<NUM>) coupled to the ampule by a friction fit such that a central longitudinal axis of the ampule and a central longitudinal axis of the housing are aligned; and
(d) an insert (<NUM>) disposed within the housing, the insert having
(i) a well (<NUM>) within which at least a portion of the second dome is disposed;
(ii) a ramp (<NUM>) angled at least <NUM> degrees relative to the central longitudinal axis of the ampule and in contact with the second dome of the ampule, the ramp being configured to apply a first reaction force at the point of contact with the second dome of the ampule when a compressive force is applied between the cap and the housing along the direction of the central longitudinal axis of the housing; and
(iii) a stress concentrator (<NUM>) disposed adjacent to the sidewall of the ampule, the stress concentrator being configured to apply a second reaction force against the sidewall (<NUM>) of the ampule when the first reaction force is applied, thereby facilitating breakage of the ampule (<NUM>).