WO2022012757A1

WO2022012757A1 - Process challenge device (pcd) with variable sensitivity adaption

Info

Publication number: WO2022012757A1
Application number: PCT/EP2020/070313
Authority: WO
Inventors: Ulrich Kaiser
Original assignee: Gke Gmbh
Priority date: 2020-07-17
Filing date: 2020-07-17
Publication date: 2022-01-20

Abstract

PCD (2), comprising a housing (12+18) and an indicator chamber (20) containing an indicator (26), wherein the total indicator volume is a summary of the indicator chamber volume and the additional adjustable volume (24), And wherein the total indicator vol- ume can be modified according validation requirements, which is able to change the sensitivity of the PCD.

Description

Process Challenge Device (PCD) with variable sensitivity adaption

Background

In sterilization processes, process challenge devices (PCDs) are used to monitor the sterilization gas distribution in a sterilization chamber. Those PCDs must simulate the penetration characteristics of the instruments to be sterilized to assure that the steriliza tion gas is reaching the most difficult areas inside the instruments to get sterility there. Today more and more minimal-invasive operations are carried out where very complex arthroscopic instruments with tiny channels are used.

PCDs simulating those complex instruments must therefore provide adequate difficult gas penetration characteristics to be equal or better like the sterilized instruments in terms of the gas penetration to monitor that sterility is achieved. Today, those PCDs are designed using cotton or paper packs at different sizes with a biological or chemical indicator inside or PCDs with tubes of different length and diameter, whereby an indica tor chamber with the indicator inside is closing one end of the tube and the other end is open and connected to the sterilization chamber (see figure 5).

Multiple PCD versions are available on the market with simple or complex penetration characteristics necessary to simulate the different penetration characteristics of the in struments in use.

One of the main critical variables of a PCD construction is the volume of the chamber wherein a biological or a chemical indicator is located to check if sterilizing gas is reach ing the indicator to provide information that the sterilization process being successful in the most difficult sterilization areas into the PCD. The indicator chamber volume is heavily influencing the difficulty of the gas penetration. Only sterilization processes with initial pressure pulsing programs can remove the air inside the indicator chamber and can exchange the air inside against the sterilizer gas.

According to the gas law, as larger the chamber volume is, as easier the gas exchange between air and the sterilization gas is achieved during a pulsing sterilization process compressing or expanding the air in the indicator chamber volume. The sterilant gas reacts with chemical or biological indicators positioned inside the chamber. The smaller the indicator chamber volumes are, the more difficult is the sterilizing gas to penetrate with pressure pulsing of the sterilizer. Normally different PCDs are tested during valida tion of the sterilization process to find an adequate PCD simulating the difficult to pene trate instruments.

The document EP 1 308 175 A1 discloses a sterilization process challenge device with a sterilization indicator contained within a container and a variable diffusion restriction into said container.

The document US 5,801,010 discloses a self-contained biological indicator which is comprised of a plurality of generally cylindrical, telescoping vials being operable from an unsealed, sterilization test configuration to a sealed and activated configuration for in cubation.

Summary of the invention

The object of the invention is to provide only one PCD which allows performing valida tion of sterilization processes with different sensitivity in an economic way.

Preferred embodiments of the invention are described in the dependent claims and the figures 1 -4.

The invention therefore relates to a process challenge device (PCD), comprising a housing and an indicator chamber for receiving an indicator, whereby at least one vol ume adjusting element is provided for adjusting the volume of said indicator chamber, which automatically changes the sensitivity of the PCD. The invention is based on the consideration that currently, a company has to offer sev eral PCDs with different sensitivities to fulfil the customer requirements.

The applicant has found by providing a PCD with an indicator chamber which can be adjusted in volume size, only one PCD design can serve for all validation requirements where the sensitivity can be easily adjusted by changing the chamber volume.

The indicator chamber thereby comprises two volume connected parts, namely the in dicator chamber in which the indicator is provided, and the part of the channel reaching from the indicator chamber to the volume adjusting element which becomes now part of the indicator chamber. As the volume size of the supplemental indicator chamber is adjusted, the total volume of the indicator chamber is changed.

Preferably, a channel is provided in the housing which is connected to the indicator chamber, whereby the volume adjusting element is moveable arranged within the channel such that the volume of the indicator chamber extends in the channel up to the volume adjusting element.

The channel is advantageously built as a bore with an inner thread, whereby the vol ume adjusting element is built as a grub screw which can be turned in the bore in both rotational directions. By just turning the grub screw to increase or decrease the indicator chamber volume and therefore the sensitivity of the same PCD construction can be modified quickly during the validation procedure.

The bore with the inner thread preferably comprises a dead end located within the housing.

Preferably, the bore is connected to the indicator chamber and to the outside of the housing such that the grub screw for changing the volume can be operated from out side during operation of said PCD.

Advantageously, the grub screw inside the bore is made from metal or favourable from an elastic plastic or rubber material to get a 100 % seal inside the bore. The bore thread diameter preferably is M4, M6 or M8 with a matching grub screw in side.

The indicator chamber is alternatively connected with a channel, especially a bore hole, containing a plunger, whereby the plunger is moveable in both directions in the channel, thereby changing the total indicator chamber volume and the remaining channel volume (Fig. 3).

The plunger advantageously can be fixed on different positions from the outside of the channel.

The housing is made preferably made from metal, especially stainless steel, plastic, like PP.

The bore and the grub screw can advantageously be blocked and sealed with a special sealing wax such that the grub screw cannot be turned anymore and the volume re mains unchanged. After the validation, the grub screw and bore thread is sealed with sealing wax and the PCD can be used without any change of sensitivity because the screw adjustment is not visible to the user during routine monitoring and cannot any more be modified.

The PCD is preferably built with two housing parts and channels created between these two parts as described in the patent applicant WO 2020/038566 A2 filed by the appli cant of which the content is fully integrated hereby.

Besides the PCD invention of the applicant above any standard PCD where the indica tor capsule is closed with a seal, can be used alternatively with the described invention. The invention therefore relates a PCD with a housing and an indicator chamber which can be adjusted in its total volume.

Besides a chemical indicator used in the capsule of the invention any other chemical or biological indicator, self-contained biological indicator, self-contained biological indicator with enzyme reaction or self-contained biological indicator with chemical indicator re lease for all types of sterilization processes can be used.

The advantages of the invention are especially as follows. If a PCD is used with an indi cator chamber where the volume can be easily modified, according the invention, only one PCD is required where the optimal sensitivity can be adjusted during the validation procedure. Several PCDs with different sensitivities have always step differences be tween two PCDs. Using the PCD according to the invention in which the sensitivity can be adjusted, a sensitivity fine-tuning can be carried out optimally.

The indicator capsule volume adjustment can be changed in very tiny steps or also large differences during a validation procedure is carried out making small or large ad justments only using always the same PCD of the invention. The PCD can be adjusted to have a larger or smaller volume without changing the construction of the PCD.

The PCD according to the invention allows an easy adjustment and will save cost for the manufacturing company in making only one PCD version and to be able to produce larger quantities of the same PCD at lower cost. The add-on cost making a thread hole is lower in manufacturing cost than producing PCDs with different capsule volume or tube length or other design variations to create different PCD sensitivities.

Validating specialists don’t need to know in advance which PCD sensitivity has to be purchased because they can use the same PCD for all applications just validating the PCD sensitivity for their sterilization process they intend to validate. The PCD according to the invention can be used for all sterilization processes (steam, ethylene oxide, for maldehyde, hydrogen peroxide).

Brief description of the drawings

Further features and advantages of the present invention shall become clearer from the following detailed description of some of its preferred embodiments, made with refer ence to the attached schematic drawings and given as an indication and not for limiting purposes. ln particular, the attached drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings together with the description explain the principles of the invention. In the drawings, corresponding characteristics and/or components are identified by the same reference numbers. In these drawings:

FIG. 1a shows a PCD with an adjustable indicator chamber volume in a first preferred embodiment with a housing comprising an outer and an inner housing part;

FIG 1 b shows the outer and inner housing parts of the PCD of FIG. 1 a separated from each other, wherein the adjustment is carried out inside the PCD with a grub in a bore thread;

FIG. 2 shows a PCD with an adjustable indicator chamber volume in a second pre ferred embodiment; where the adjustment is carried out from outside grub in the bore thread

FIG. 3 shows a PCD with an adjustable indicator chamber volume in a third preferred embodiment, wherein the adjustment is carried out with an adjustable plunger; and

FIG. 4 shows a PCD with an adjustable indicator chamber volume, wherein the PCD is designed as tube.

Identical parts are labelled with the same reference numerals.

Detailed Description

In FIG. 1a, a PCD (process challenge device) 2 is shown which comprises a housing 12+18 which comprises an outer housing part 12 and a head of inner housing part 18 which is inserted into the outer housing part 12. The PCD 2 comprises an indicator chamber 20. In the indicator chamber 20, an indicator 26 is arranged which can be a chemical, physical, or biological indicator. Between the outer housing part 12 and head of inner housing part 18 a plurality of con nected gas channels 30 is built. Gas entering the housing 6 in an entering region 3,6 which is built adjacent to a head of inner housing part 18, travels in a zig-zag manner before reaching the indicator chamber 20.

Inside the head of inner housing part 18, a channel 24, 40 is formed which is built as a bore 44 with an inner bore thread 48. In the bore 44, a grub screw 50 is arranged which comprises an outer thread 54 which engages with the inner bore thread 48. The chan nel 24, 40 comprises a first channel 40 which is separated from the indicator chamber 20 by the grub screw 50 and a second channel 24 which is connected to the indicator chamber 20.

In FIG. 1b, the outer housing part 12 and the head of inner housing part 18 of housing 6 are displayed separated from each other. As indicated by an arrow 64 where a socket wrench can be used, by turning the grub screw 50, the size length and thereby size and volume of the channel 24 can be changed, i.e. increased or decreased. As can be seen in FIG. 1 b and denoted by the arrow 64, the grub screw 50 can only accessed when the head of inner housing part 18 is removed from the outer hosing part 12. The bore 44 is realized as a blind bore and ends in the head of inner housing part 18 at a dead end 28. By turning the grub screw 50, the volume of the channel 24 and therefore the total volume or effective volume of the indicator chamber 20 can be adjusted, i.e. increased or decreased. In this way, different sensitivities of the PCD 2 can be realized.

In FIG. 2, a second preferred embodiment of PCD 2 is shown which also comprises a two-part housing with a head of inner housing part 18 and an outer housing part 12. In this embodiment, the bore 44 is lead through the head of inner housing part 18 to an opening 70 at the outside of head of inner housing part 18. A tool, for instance a socket wrench, can be lead into the bore 44 in order to rotate the grub screw 50 for adjusting the indicator chamber volume in the mounted state of both housing parts 12, 18. The PCD 2 therefore does not have to be dissembled for adjusting the indicator chamber volume. A further preferred embodiment of a PCD according to the invention is shown in FIG. 3. Also in this embodiment, head of inner housing part 18 comprises a channel 40. The channel 40 reaches through head of inner housing part 18 to an opening. In this em bodiment, the channel 40 does not comprise an inner thread since no grub screw 50 is used. In the present embodiment shown, a plunger 76 is arranged at least partially in said channel 40. The plunger 76 comprises a plunger seal 78 facing the indicator chamber 20 which modifies the volume of the indicator chamber 20.

The plunger 76 is partly located outside of the head of inner housing part 18 and allows a convenient handling. The PCD 2 comprises a latching device 82 for adjusting the depth of plunger 76 in channel 40. The latching device 82 comprises a plurality of latch ing hooks of which three are indicated by reference numerals 84. A latching bar 86 is pivotable mounted to the head of inner housing part 18 and is built to engage with a latching hook 84. In this way, the axial position of the plunger 76 with respect to the channel 40 can be fixed, allowing precise measurements of the sterilization process.

Still a further preferred embodiment is shown in FIG. 4. The PCD 2 comprises a tube 90 connected to a housing 6 in which the indicator chamber 20 is arranged which compris es the indicator chamber 20 and the supplemental indicator chamber 24. In housing 6 a channel 40 is built as a bore 44 with an inner bore thread 48 in which a grub screw 50 with an outer thread 54 is arranged. The channel 40 reaches through housing 6 up to an opening 92 in housing 6 and the grub screw 50 can therefore be operated from the outside and without disassembling the PCD 2.

P200242P

List of reference numerals

2 Process challenge device (PCD)

6 housing

12 outer housing part

18 head of inner housing part

20 indicator chamber

24 channel

26 indicator

28 dead end

30 channels

36 entering region

40 channel

44 bore

48 inner bore thread

50 grub screw

54 outer thread

64 arrow = socket wrench

70 opening

76 plunger

78 plunger seal

82 latching device

84 latching hooks

86 latching bar

90 PCD designed with a tube

92 opening

Claims

1. PCD (2), comprising a housing (12+18) and an indicator chamber (20) with an indicator (26) inside, whereby a volume adjusting element (50+24; 76) is provid ed for being able to change the total indicator volume (20+24) without changing the construction of the PCD

2. PCD (2) according claim 1, whereby a channel (24, 40) in said housing (12+18) is provided which is connected to said indicator chamber (20), and whereby said volume adjusting element (50+24; 76) is moveable arranged within said channel (24, 40) such that the volume of indicator chamber (20+24) extends in said channel (24) up to said volume adjusting element (50, 76).

3. PCD (2) according to claim 2, whereby said channel (40) is built as a bore (44) with an inner thread (48) and whereby said volume adjusting element (50+76) is built as a grub screw which can be turned and moved in said bore (44) with the inner thread (48) in both rotational directions.

4. PCD (2) according to claim 3, whereby said bore (44) with said inner thread (48) comprises a dead end (28) located within the inner housing (18) where the grub screw can be operated through the indicator chamber with a socket wrench.

5. PCD (2) according claim 3, whereby said bore (44) is connected to said indica tor chamber (20) and to the outside of said inner housing part (18) such that said grub screw (50) for changing the volume can be operated from outside during operation of said PCD (2).

6. PCD (2) according to one of the claims 3 to 5, whereby said grub screw (50) in side said bore thread (44) is made from metal or favourable from an elastic plas tic or rubber material to get a 100 % seal inside the bore (44).

7. PCD (2) according to one of the claims 3 to 6, whereby said bore (44) and said grub screw (50) can be blocked and sealed with a special sealing wax such that the grub screw (50) cannot be turned anymore and the volume remains un changed.

8. PCD (2) according to one of the claims 1 to 6, whereby said bore (44) thread di ameter is for example M4, M6 or M8 with a matching grub screw (50).

9. PCD (2) according claim 1 , whereby said indicator chamber (20) is connected to a channel (40) containing a sealed plunger (76), whereby said plunger (76) is moveable in both directions in said channel (40), thereby changing the total indi cator chamber volume including the remaining channel volume (40).

10. PCD (2) according to claim 9, whereby said plunger (76) can be fixed on different positions from the outside of said channel (40).

11. PCD (2) according to one of the claims 1 to 10, whereby said inner and outer housing (12, 18) is made from metal, especially stainless steel, plastic, for ex ample PP.

12. PCD (2), wherein the indicator chamber (20) is connected according to one of the claims 1 to 11 to a tube (90) acting as a PCD.

13. PCD (2) according to claims 1 to 12, wherein the PCD type may be all types of conventional PCD using a seal for closing the indicator capsule.

14. PCD (2) according to claims 1 to 13, wherein the indicator may be any type of chemical indicator, biological indicator, self-contained biological indicator, self- contained biological indicator with enzyme reaction or self-contained biological indicator with chemical indicator release for all types of sterilization processes.