FR2842740A1 - METHOD AND DEVICE FOR STERILIZING OBJECTS OF COMPLEX SHAPES - Google Patents

Abstract

Process for sterilizing at room temperature at least one object of complex shape (15) placed in a sealed treatment chamber (14) subjected to substantially atmospheric pressure and into which is introduced a biocidal gas mixture, process in which the introduction of this biocidal gas mixture in the treatment enclosure is preceded by a step of suctioning the non-biocidal gas mixture initially present in this enclosure, so as to reduce the duration of filling the enclosure with the biocidal gas mixture.

Description

The invention relates to the general field of sterilization of

  complex forms from active biocidal gas mixtures at a temperature close to ambient and at a pressure close to atmospheric pressure. PRIOR ART Application WO 0054819, filed in the name of the applicant, discloses atmospheric pressure plasma objects and surface sterilization devices in which one or more

  treat are arranged in treatment chambers.

  In the case of objects of complex shapes, variables and large size, the design of the treatment enclosure however poses special problems. Indeed, it is not always possible for economic reasons to design enclosures dedicated to each type of equipment and adjusted to their shapes. Consequently, the objects to be treated having the largest dimensions generally determine the size of the treatment chamber and the internal volume of the chamber can then be very large compared to that of the object to be treated. As a result, the total treatment time, including the filling of the chamber, the contacting of the active chemical species and the purge of the chamber,

  is thus unnecessarily lengthened.

  During the filling of the treatment chamber, the active chemical species generated by the plasma are diluted in the volume of the treatment chamber. Moreover, the complex shape of certain objects represents an additional difficulty for obtaining a uniform treatment over the entire surface of the object, especially in the access zones.

the most difficult.

  During the treatment, it is necessary to improve the homogeneity of the gaseous mixture, to promote its introduction into these most difficult access zones and to limit the points of contact between the object to be treated and

the treatment chamber.

  Finally, during the purge phase, the active chemical species generated by the plasma must be replaced by a nonbiocidal gas mixture. However, this one tends to be diluted in the volume of the enclosure of

  treatment, which increases the time of this purge phase.

  These problems are particularly present on objects with complex shapes and containing areas of difficult access, such as nondebouchant and open cavities, such as endoscopes which in addition one of its dimensions, its length, is large in front of others. Indeed, the treatment of endoscopes must take into account both: - particularly complex forms of treatment devices, - a wide variety of dimensions of endoscope insertion sheaths (from 25 cm to 250 cm), a need for treatment as short as possible to optimize the time of use of the instruments, and - an absolute guarantee of the quality of the treatment in the least

nooks of the object.

  OBJECT AND DEFINITION OF THE INVENTION The invention proposes to overcome these disadvantages with an improved sterilization process allowing rapid processing of objects of complex or large shapes. An object of the invention is also to propose an improvement to a sterilization process whose

  biocidal gas mixture is developed or not from a plasma.

  These objects are achieved by a method of sterilization at ambient temperature of at least one object of complex shape placed in a sealed treatment chamber subjected substantially to atmospheric pressure and into which a biocidal gas mixture is introduced, characterized in that the introduction of this biocidal gas mixture into the treatment chamber is preceded by a step of suction of the nonbiocidal gas mixture present initially in this chamber, so as to reduce the duration of filling of the chamber with the biocidal gas mixture. The biocidal gas mixture can be obtained by creating a plasma from a non-biocidal gas mixture preferably comprising at least% oxygen and 10% nitrogen (advantageously ambient air) and by

humidification.

  When the treatment chamber is rigid (that is to say, little or no deformable), the suction of the non-biogenic gas mixture present in this chamber creates a reduction in its internal pressure. This aspiration of the non-biocidal gas mixture is sufficiently strong to make a partial vacuum in the treatment chamber and thus allow the biocidal gas mixture to reach cavities that are difficult to access.

the object to be treated.

  When the treatment chamber is flexible, the aspiration of the non-biogenic gas mixture present in this chamber creates a reduction in its volume. Applied to the treatment of objects having through channels, this aspiration is preferably carried out locally for

  to allow treatment of these difficult to access channels.

  Advantageously, the suction step is also performed during a purge phase of the treatment chamber, so as to reduce the duration. Similarly, one or more suction steps can be performed during the treatment to promote circulation and homogenization of the biocidal gas mixture around the object, each suction step being followed immediately by an injection step of a determined volume of

biocidal gas mixture.

  The invention also relates to the sterilization device implementing the aforementioned method and comprising a first suction means connected at the outlet of the treatment chamber for selectively aspirating the gaseous mixture present in this chamber, so as to reduce the duration of sterilization and increase its effectiveness. Depending on the type of enclosure, rigid or flexible, the first suction means comprises a vacuum pump or a venturi effect system. When the object to be treated comprises through channels, it is furthermore advantageously provided a second suction means, comprising a venturi effect system, connected to these through channels to suck the gaseous mixture circulating in these difficult to access channels. Preferably, the through channels of the object to be treated are connected to the second suction means via transport ducts.

  crossing the treatment chamber.

Brief description of the drawings

  Other features and advantages of the present invention

  better from the following description given as an indication and not

  FIG. 1A is a block diagram of a plasma sterilization device to which the improved method of the invention is applicable. FIG. 1B is a block diagram of a sterilization device. FIG. By a biocidal gas to which the improved process of the invention is applicable, FIGS. 2A to 2D illustrate the successive stages of aspirations and injections of the improved process of the invention in the case of a non-deformable or very non-deformable enclosure. 3A to 3E illustrate the successive steps of aspirations and injections of the improved method of the invention in the case of a deformable enclosure.

  Detailed description of preferred embodiments

  The invention relates to an improvement in sterilization processes, and in particular plasma sterilization processes using one or more non-biocidal gas mixtures from which are created one or more low temperature plasmas whose chemical species have a sterilizing action on the object to be treated in the presence of moisture. The object to be treated is placed outside the space where the electric discharge takes place and the treatment is done substantially at atmospheric pressure. Applications WO 00/54819 and WO 02/22180 filed in the name of

  Applicant illustrate this type of process.

  Plasma is a gas partially activated by an electromagnetic energy source adapted to the desired level of sterilization

  (A simple disinfection can thus also be obtained by this process).

  The species created in plasma are ionized species (molecules or atoms), neutral (such as radicals) or excited. These gaseous species have an increased reactivity that allows them to interact with

  surfaces of the object (s) to be treated and thus destroy the microorganisms or bacteria present on these surfaces.

  According to the invention, it is proposed to modify the basic processing cycle as described in WO 00/54819 so that it has a shorter processing time and is better suited to the processing of shape objects. complexes and especially the objects of

  elongated form such as endoscopes.

  To do this, it is proposed to rapidly exchange a gaseous mixture with another gaseous mixture, generally in the treatment chamber or locally on the object to be treated, by means of one or more suctions and / or successive injections of these gas mixtures. This exchange can take place during the filling phase of the enclosure and its phase of

  purge but also during the treatment phase.

  Thus, during the filling phase, it is necessary to quickly replace the non-biocidal gas mixture with a biocidal gas mixture and the opposite during the purge phase. During the treatment phase, the homogenization of the biocidal gas mixture can be obtained by one or more suctions and / or successive injections. In the case where the treatment chamber is formed of a rigid envelope, that is to say non-deformable or slightly deformable, the overall suction of the gas present in the treatment chamber during the filling phase must be large enough to create a pressure reduction in the treatment chamber that will depend on the mechanical strength of the enclosure and the object to be treated. The reduction of pressure and the injection of biocidal gas mixture into the treatment chamber prevent its dilution and promote its penetration into the non-emergent cavities of the object to be treated. During the treatment, suction and injection cycles can also be applied to ensure homogeneity of treatment around the object. And, during the purge phase, the evacuation of the biocidal gas mixture and its replacement by a non-biocidal gas mixture are accelerated by one or more successive suction and injection stages. For the open cavities, a local depression is applied which contributes to the reduction of pressure in the enclosure and which allows their irrigation by the biocidal gas mixture throughout the treatment. In the case where the treatment chamber is a flexible enclosure, and therefore deformable, the overall suction of the gaseous mixture of the treatment chamber during the filling phase leads to the reduction of its volume around the object to be treated. When the biocidal gas mixture is introduced into the chamber, it gradually refills the chamber but it is not diluted and therefore acts more efficiently and quickly, this

  promotes the homogenization of the biocidal gas mixture in the chamber.

  These variations in shape of the flexible enclosure may further promote the elimination of existing contact points between the treatment chamber and the object to be treated. If necessary, during the treatment phase, a local suction can be applied to favor the particular irrigation of the opening cavities of the object to be treated. During the purge phase, the evacuation of the biocidal gas mixture and its replacement with a non-biocidal gas mixture can also be accelerated by one or

  several aspirations and injections.

  A schematic diagram of a first example of a plasma sterilization device 10 implementing the improved method of the invention is illustrated in FIG. 1A. This device is organized around a treatment chamber formed of a plasma production chamber 12, inside which an electric discharge between two electrodes is created a plasma, and a sealed sterilization chamber 14. is placed the object to be treated 15 (these two speakers can be independent or form a single sealed envelope 16). The electric discharge (preferably a corona discharge) is produced from a non-biocidal gas mixture supplied by a gas source 18 via a humidification chamber 20 (alternatively it will be appreciated that moisture can also be introduced directly in the sterilization chamber 14). The gaseous residues from the discharge are then discharged to a recovery system 22. The control of the treatment cycle is provided by a control unit 24 which centralizes various measurements and regulations of electrical characteristics of the plasma, temperature, humidity, ozone, etc. taken at different measuring points of the device and adjusts the rate of introduction (speed, flow) of the biocidal mixture into the chamber 14 (for example by a variable flow valve 23) and the duration of the different phases (filling, treatment , purge) of the process

sterilization.

  The moisture content and the composition of the non-biocidal gas mixture depend on the nature of the object to be sterilized and the type of micro organisms or bacteria to be destroyed. For example, the application WO 02/22180 gives examples of gaseous mixtures containing oxygen and nitrogen (typically ambient air) providing an effect

  acceptable sporicide on bacterial bacillus / ussubtilis spores.

  FIG. 1B illustrates a second example of a sterilization device at ambient temperature and atmospheric pressure at which the improvement of the invention can also be applied. In this second device, the biocidal gas mixture comes (through the restriction 23) from a reservoir 25 placed at the inlet of the treatment chamber formed of the single sterilization chamber 14. The other components of the device are unchanged with the recovery system 22 and the unit of

control 24.

  According to the invention, the sterilization device 10 further comprises, upstream of the recovery system 22, first and second suction means 26, 28 connected at the outlet of the sterilization chamber 14, via an evacuation pipe with a large diameter 30 and a small diameter drain pipe 32. The first suction means 26 creates intermittently a pressure reduction (case of rigid speakers) or a reduction in volume (case of flexible speakers) in this chamber sterilization. The second suction means 28 creates a

  local depression in open cavities.

  The small diameter evacuation pipe 32 is connected in the sterilization chamber 14 by transport ducts (for example 34, 36) to the ends of each of the open channels of the endoscope 15 (with the exception, however, of the insertion sheath that is fragile and only has

no connectors).

  In the case of a flexible (deformable) enclosure, the first suction means 26 comprises a venturi system. By cons, in the case of a rigid enclosure (non-deformable or slightly deformable), the vacuum in the chamber requires a larger suction means, preferably a vacuum pump. In contrast, the second suction means can in the case of a flexible enclosure as a speaker

  rigid be made of a simple venturi effect system.

  The implementation of the method according to the invention applied to the sterilization of an endoscope is now described with reference to FIGS. 2 and 3. But, first of all, the following parameters are defined: Patm the atmospheric pressure Pl the pressure in the enclosure P2 the local pressure at the opening cavities of the object P3 the inlet pressure of the enclosure P4 the outlet pressure of the enclosure in the high-diameter circuit Pdef the pressure from which the endoscope starts to deform locally

  Take the pressure of rupture of the enclosure.

  The case where the enclosure is not deformable or very little deformable is

illustrated in Figures 2A to 2D.

  Before the injection of the biocidal gas mixture into the sterilization chamber (FIG. 2A), the method consists in applying a suction of the gas already present in this chamber. To do this, the inlet of the biocidal gas mixture is cut by the valve 23 and to allow evacuation, the low-flow evacuation pipe 32 is closed (for example at the level of the system 28). The suction means 26 formed of a vacuum pump is then activated. The gas already present in the enclosure is then sucked into the pipe 30 by this first suction means 26, until a

defined pressure threshold.

  This action has the effect of displacing the gas already present in the chamber out of it by removing all or part of the gas mass, thus creating a partial vacuum, the level of which will depend, among other things, on the mechanical strength of the gas. enclosure and resistance to deformation of the endoscope. The goal is to remove as much gas as possible from the enclosure, without damaging it or deforming the endoscope. A compromise on the adjustment of the suction vacuum must therefore be achieved. Before the aspiration Pl, P2, P3 and P4 = Patm After the suction, Pl <P3 and P1 <P4, with P1 <Pcrit and P1 <Pdef P1 = P2 and P2 <Pdef The filling phase takes place then (figure 2B), during which the biocidal gas mixture is introduced into the sterilization chamber with possibly a slight pressurization of the chamber. During the injection, the suction system 26 is stopped. The biocidal gas mixture therefore enters the chamber and is sucked by the suction system 28, via the internal channels of the endoscope and the circuits 34 and 36. The suction flow rate of 28 may be less than the flow rate. Inlet, the biocidal gas mixture can also flow freely in the

pipe 30.

  After the injection, P1> or = Patm, with P1 <Pcrit and P1 <Pdef

  Pl = P3, Pl> or = P4 and P2 <or = Pl.

  This implementation greatly reduces the dilution of the biocidal gas mixture as it is introduced into the sterilization chamber and promotes the penetration of the biocidal gas mixture into the non-emerging cavities. Irrigation of the opening cavities is facilitated by the operation of the second suction means 28 in connection with these channels through the ducts.

transport 34, 36.

  During the treatment phase (FIG. 2C), one can advantageously

  perform one or more successive phases of aspiration and injection.

  Possibly light pressurization can be applied

during the injection phases.

  During this phase, and as long as there is no aspiration-injection, the first suction means 26 is not in operation (it is bypassed) and the gaseous mixture present in the treatment chamber can flow freely to the outside (the recovery system 22), via the large-diameter discharge circuit 30. However, during all this phase, the second suction means 28 can advantageously be in operation.

  operation for irrigation of the internal channels of the endoscope 15.

  During an aspiration-injection, the first suction means 26 is put into operation, with a flow rate such that the flow rate in the pipe 30 is greater than the inlet flow rate. The biocidal gas mixture contained in the sterilization chamber 14 can then be evacuated very quickly, depending on the imposed flow rates at the outlet of the latter. To finish the suction, it is then sufficient to cut the operation of the first suction means 26. This operation, which can be repeated several times during the treatment phase, allows, firstly, to dynamically renew the gas mixture biocide in the sterilization chamber and,

  on the other hand, to homogenize the treatment on the surfaces of the endoscope.

  At the end of the cycle (FIG. 2D), before the purge phase, it is also possible to apply a new aspiration phase of the biocidal gas mixture before the injection of a purge gas. As previously in the filling phase, the injection of the biocidal mixture is cut off, the first suction means 26 is activated and the second suction means 28 is cut. The biocide mixture contained in the enclosure is then sucked into the pipe 30 by the first suction means 26. This action has the effect of moving the sterilizing gas mixture out of the enclosure by removing all or part of the mass of the gas , thus creating a partial vacuum, the level of which depends, among other things, on the mechanical strength of the enclosure and the endoscope. The goal is to remove as much gas as possible from the enclosure, without damaging the enclosure, nor deforming the endoscope whose opening channels will also be emptied by activation of the second suction means once the first suction means. chopped off. A compromise on the adjustment of the suction vacuum must of course be achieved. The process then makes it possible to reduce the dilution of the purge gas in the biocidal gas mixture. It thus reduces the purge time.

  The case where the enclosure is deformable is illustrated in FIGS. 3A to 3E.

  Before the injection of the biocidal gas mixture into the chamber (FIGS. 3A and 3B), the process consists of an aspiration having the effect of reducing the volume of the flexible enclosure around the object to be treated, in this case l endoscope and, in addition, to create local suction in the internal channels of the endoscope. However, because of the flexible nature of the enclosure the first suction means 26 is no longer made of a

  vacuum pump but simply a venturi effect system, for example.

  The second suction means 28 is, on the other hand, as before,

  always a venturi effect system.

  To do this, the inlet of the biocidal gas mixture is cut by the restriction 23 and the two suction means 26 and 28 are activated. The gas already present in the enclosure is then sucked into the pipe 30 by the first suction means 26 and into the pipe 32, via the internal channels of the endoscope 5 and the transport pipes 34 and 36, by the second suction means 28. The suction by the two suction means 26 and 28 is carried out until a predefined reduction of the

volume of the treatment enclosure.

  Before aspiration P1, P2, P3 and P4 = Patm After aspiration Pl = P3 = P4 with Pl <Pcrit and Pl <Pdef

  P2 <Pl, and P2 <Pdef with a variation of volume.

  When the biocidal gas mixture is introduced into the chamber (FIG. 3C), it gradually inflates the chamber but is not diluted and therefore acts more efficiently and more rapidly. During the injection, the suction system 26 is stopped. The biocidal gas mixture therefore enters the chamber and is sucked by the suction system 28, via the internal channels of the endoscope and the circuits 34 and 36. The suction flow rate of 28 may be less than the flow rate. "entry, the biocidal gas mixture may

  also flow freely in line 30.

  After the injection, P1> or = Patm, Pl = P3 = P4 with P1 <Pcrit and Pl <Pdef P2 <P1, and P2 <Pdef with a variation of volume During the treatment (Figure 3D), one or more successive steps suction and injection as described above can also

to be carried out.

  These variations in shape of the flexible enclosure may further promote the elimination of possible points of contact between the sterilization enclosure

and the endoscope to be treated.

  At the end of the cycle (FIG. 3E), as in the preceding embodiment, an aspiration is carried out which will promote the evacuation of the biocidal gas mixture by decreasing the dilution of the purge gas therein. The injection of the biocidal mixture is cut off, and the suction means 26 and 28 are activated. The biocide mixture contained in the enclosure is then sucked into the pipe 30 by the first suction means 26 and into the pipe 32, via the internal channels of the endoscope 5, by the second suction means 28. This action has the effect of moving the biocidal gas mixture out of the enclosure by removing all or part of the mass of the gas, thereby creating a reduction in the volume of the treatment chamber. The process then makes it possible to reduce the dilution of the purge gas in the biocidal gas mixture. he

thus decreases the purge time.

  The improved method of the invention has been described more particularly in the context of the sterilization of an endoscope, in a rigid or flexible enclosure. But, of course, this embodiment can not be limiting and the invention can be implemented in other areas that the medical field, for example the agricultural or agri-food, industrial or military. In the military field, for example, there is a possible application for the decontamination of weapons

  contaminated by bacteriological species.

Claims (16)

claims   1. A method for sterilizing at ambient temperature at least one complex-shaped object (15) placed in a sealed treatment chamber (14) substantially subjected to atmospheric pressure and into which a biocidal gas mixture is introduced, characterized in that the introduction of this biocidal gas mixture into the treatment chamber is preceded by a step of suctioning the non-biocidal gas mixture initially present in this chamber, so as to reduce the duration of   filling the chamber with the biocidal gas mixture.   2. Method according to claim 1 wherein the biocidal gas mixture is obtained by creating a plasma from a non-gaseous mixture. biocide and by humidification.   3. The method of claim 2 wherein the nonbiocidal gas mixture contains at least 10% oxygen and 10% nitrogen.   4. A process according to any one of claims 1 to 3 wherein the   Non-biocidal gas mixture is the ambient air.   The method of any one of claims 1 to 4 wherein   the treatment chamber is rigid and where the aspiration of the non-biocidal gas mixture present in this chamber creates a reduction in its internal pressure. 6. The method of claim 5 wherein the suction of the non-biocidal gas mixture is strong enough to make a partial vacuum in the treatment chamber and thus allow the biocidal gas mixture   to reach inaccessible cavities of the object to be treated.   The method of any one of claims 1 to 4 wherein   the treatment chamber is flexible and o aspiration of the non-biogenic gas mixture present in this chamber creates a reduction in its volume. 8. The method of claim 7 applied to the treatment of objects having through channels, wherein the suction is further performed locally to allow treatment of these channels. difficult to access.   9. Process according to any one of claims 1 to 8 in which   also applies the suction step during a purge phase of   the treatment chamber, so as to reduce the duration.   The method of any one of claims 1 to 5 wherein   one or more suction steps are also applied during the treatment to promote circulation and homogenization of the biocidal gas mixture around the object, each suction step being followed immediately by a step of injecting a volume determined from biocidal gas mixture.   11. Device for sterilization at ambient temperature and in the presence of moisture of at least one complex-shaped object (15) placed in a sealed treatment chamber (14) substantially subjected to atmospheric pressure and into which a gas mixture is introduced biocide, characterized in that it comprises a first suction means (26) connected at the outlet of the treatment chamber for selectively aspirating the gaseous mixture present in this chamber, so as to reduce the duration   sterilization and increase its effectiveness.   12. Sterilization device according to claim 11 wherein the treatment chamber is rigid, characterized in that said first   suction means comprises a vacuum pump.   13. Sterilization device according to claim 11 wherein the treatment chamber is flexible, characterized in that said first   suction means comprises a venturi effect system.   14. sterilization device according to claim 12 or claim 13 wherein the object to be treated comprises through channels, characterized in that it further comprises a second suction means (28) connected to the through channels to suck the gas mixture circulating in these channels difficult to access. 15. Sterilization device according to claim 14, characterized in that   said second suction means comprises a venturi system.   16. Sterilization device according to claim 14 or claim, characterized in that said through channels of the object to be treated are connected to the second suction means via air ducts.   transport (34, 36) passing through the treatment chamber.