GB2364622A

GB2364622A - Sterilising apparatus and method using UV lights and filtered air flow

Info

Publication number: GB2364622A
Application number: GB0105995A
Authority: GB
Inventors: Leonard Wilson
Original assignee: Afos Ltd
Current assignee: Afos Ltd
Priority date: 2000-03-20
Filing date: 2001-03-12
Publication date: 2002-01-30
Anticipated expiration: 2021-03-12
Also published as: IE20010247A1; GB0006616D0; GB2364622B; GB0105995D0

Abstract

Apparatus and a method for sterilising endoscopes are described. The apparatus includes a cabinet having a pair of swing doors which position is sensed so that when the doors are closed, filtered air is driven by a fan into the interior of the cabinet at a slight positive pressure to prevent the ingress of ambient air from outside the cabinet. While the cabinet is closed, a series of bactericidal ultra-violet lights are activated intermittently to ensure not only that bacteria do not proliferate during operation but also that such bacteria are actively destroyed. The cabinet ideally is provided with hooks for suspending the endoscopes and a number of connectors which may optionally be integral with the hooks by which filtered air can be driven through the interior of the endoscope as well as over their exterior surfaces.

Description

2364622 Sterilisation Apparatus and Method This invention relates to a

sterilisation apparatus and method, and more particularly to apparatus ideally adapted for the sterilisation of medical equipment.

Although the following description is provided with exclusive reference to the provision of apparatus for the sterilisation of medical equipment in general, and in particular endoscopes, it will be appreciated by those skilled in the art that the apparatus and method proposed by the invention can be used for any particular apparatus which is required to be sterile before use, and in particular substantially free from bacteria which proliferate in moist warm environments. Examples include biological apparatus used in experimentation and testing, surgical and medical implements, and possibly fabric and cloth items which are required to be rendered sterile to a particularly high degree. Hereinafter the term "sterile" is to be read as meaning that the bacteria population present within or on a particular item is reduced below a predetermined level which is regarded as acceptable to the medical profession and essentially removes any possibility that use of the item in a medical procedure may infect a patient.

In all modern hospitals and many modern clinics endoscopes are widely used for the surgical inspection of the interior of a human body, in particular the tracheal, rectal, and oesophagal pathways. In the light of the fact that these endoscopes have lengthy snake-like components which are insetted within human individuals, it is imperative that such components, and indeed the entire apparatus be rendered sterile to a predetermined degree to ensure that the risk of infection of said human is precluded.

Currently, endoscope storage cabinets are provided in hospitals and clinics, and after every operative or surgical procedure in which the endoscope is utilised it must be cleansed and disinfected in a bactericidal solution before being hung and stored in the cabinet. The cabinet may be locked and the time at which the disinfected endoscope deposited therein may be logged by the surgeon, his assistant or the clinician to enable quick assessment of the length of time that has elapsed since the previous use of the said endocscope.

As is well known, certain bacteria and other contaminant organisms proliferate in conditions of moisture and warmth, and the perennial difficulty with the simple cabinet storage arrangement described above is that there is no active sterillsation of the endoscope conducted while it is being stored in said cabinet. There is thus no means of establishing, other than be calculating the time elapsed since the previous cleaning and disinfection of the endoscope, whether said endoscope as a whole is sufficiently sterile to be used in an operative or inspection procedure. The rate of bacteria proliferation can vary significantly depending on the conditions within the cabinet, and in general surgeons and clinicians alike are instructed to clean and disinfect endoscopes which have been stored in the cabinet for periods of time exceeding four hours. In most case, and in the interests of safety, endoscopes are always cleaned and disinfected after and before any operative or inspection procedure. The cleansing and disinfecting process is time consuming and labour intensive, and there therefore exists a need for a means of ensuring that endoscopes are sufficiently sterile prior to use without the repetition of cleansing and disinfection thereof.

In sterile test laboratories and in some hospitals there are provided socalled "pass-through" chambers in which filtered air at an ambient pressure is delivered into the chamber and allowed to flow within the chamber before escaping to the ambient atmosphere. The air is filtered so as to remove any bacteria or other organisms which may be present and the resulting environment within the pass through chamber is considered to be sterile.

However, the mere passing of a filtered air source through the chamber only provides an environment which reduces the moisture in said chamber and therefor only reduces the propensity of the bacteria and other organisms to proliferate. Such chambers would be ineffective as regards the sterilisation of medical and surgical equipment such as endoscopes because there remains a possibility that the bacteria can still multiply in this environment. There is currently no storage apparatus or means for ensuring that the number of bacteria, pathogens, organisms and like contaminants is actually reduced while said equipment is stored therein.

It is an object of the invention therefore to provide a means for ensuring that equipment deposited therein is rendered sufficiently sterile for use in operative and/or inspection procedures.

It is a further object of this invention to provide apparatus which reduces the number of bacteria or organisms extant on a particular item during the time said item is stored within the apparatus.

According to the invention there is provided a cabinet defining an interior in which articles to be sterilised can be stored, said cabinet having access means which can be opened and closed to allow access to said interior, said cabinet being further provided with primary air flow creation means including filtration means by which the interior of the cabinet is supplied with filtered air substantially free from contaminants, said cabinet further allowing said air to escape from the interior to the ambient atmosphere, characterised in that the cabinet interior is provided with one or more bactericidal ultra-violet lights activatable when the access means are closed and in that the air flow creation means creates a positive pressure differential within the cabinet interior while the access means are closed such that there is substantially continuous flow of filtered air from the interior of the cabinet through the escape means and ambient air is prevented from ingress into said interior thereby during the operation of the air flow creation means.

Preferably the pressure differential between the interior of the cabinet and the ambient surrounding atmosphere is approximately +15 Pascals.

Preferably the activation of the air flow creation means is dependent on the closure of the access means, and further preferably the air flow creation means is activated continuously while the access means are closed.

Preferably the cabinet is provided with hanging means from which endoscopes can be suspended and is of a sufficient height to receive said endoscopes when hung from one of their ends.

Preferably the cabinet is provided a plurality of UV lights within the interior.

Preferably the access means constitute hinged doors provided in one of the walls defining the cabinet interior.

Most preferably the pressurised air within the cabinet escapes through the gaps between the hinged doors and the cabinet wall in which they are provided.

Preferably the air flow creation means and filtration means is provided in an upper portion of the cabinet and delivery of filtered air is effected downwardly into the interior of said cabinet.

It is further preferable that the cabinet further comprises means for generating a secondary flow of filtered air delivered to a plurality of connectors which allow for connection of apparatus having hollow tubular portions and through which air can be driven by said secondary air flow creation means when said apparatus is connected thereto.

Preferably the secondary air flow generation means communicates with the primary air flow creation means and derives its air therefrom.

Alternatively the secondary air flow generation means comprises a secondary air compressor including filtration means which drives filtered air through the connectors into the apparatus connected thereto.

Preferably the connectors are adapted for connection to distal ends of endoscopes.

Preferably the surfaces of the cabinet interior at least partially reflect the UV light shone within said interior.

Preferably the interior walls of the cabinet and the access means are manufactured in a stainless steel.

Preferably sensor means are provided in the cabinet to detect the closure of the access means, said sensor means communicating with the air flow creation means to activate same when said access means are closed.

Preferably the UV lights are activated for short periods of time while the access means are closed, most preferably for 15 minutes.

Preferably the cabinet is provided with internal sensors which detect the operation of the UV lights and communicate with a validation system which further includes indication means visible externally of the cabinet which indicate to a user that the UV lights have been operative while the access means are closed, and thus that sterilisation of the apparatus within the cabinet has been effectively sterilised.

Preferably the access means is capable of being locked.

Preferably the filtration means includes a High Efficiency Particle Air (HEPA) filter.

Preferably the cabinet is provided in a trolley configuration so that it is mobile.

In a second aspect of the invention, there is provided a method of sterilising apparatus stored within a cabinet having access means which allow access to the interior of the cabinet and permit the apparatus to be deposited and removed therefrom comprising the steps of driving air filtered of bacteria and contaminants into the cabinet interior and simultaneously shining bactericidal ultra-violet light in said interior while the access means are closed.

The invention arises from the realisation of the inventor that active sterilisation can be achieved by combining a HEPA filtered air flow with the shining of UV light within the cabinet. On the one hand, the creation of a positive pressure differential within the cabinet prevents the ingress of any potentially contaminated or bacteria laden air into the cabinet, and on the other hand the bactericidal UV lights not only destroy the bacteria extant on the apparatus stored within the cabinet but also give rise to the creation of Ozone within the cabinet. It is well known that Ozone is a powerful disinfectant, and the movement of air and ozone within the cabinet provides an extremely effective means of sterilisation.

It is also to be noted that the slight positive pressure within the cabinet further enhances the production of Ozone and furthermore the movement of dry filtered through the cabinet removes moisture from within the cabinet and also from the apparatus stored therein. Bactericidal action is therefore further enhanced, and any bacteria which are not destroy are effectively inhibited from proliferating on account of the absence of moisture within the cabinet.

The injection of pressurised filtered air directly into the tubular passages or channels of the endoscope further enhance their sterilisation, , and efficacy tests conducted on the cabinet of the invention have shown surprisingly good results. Indeed unsterile endoscopes stored in the cabinet according to the invention overnight have been sterilised to such a degree that they would be sufficiently sterile for use in operative and inspection procedures without any requirement for cleansing or disinfection. Such degree of sterilisation in a storage cabinet is heretofore unprecedented.

A specific embodiment of the invention is now given by way of example with reference to the accompanying drawings wherein:

Figure 1 shows a schematic view of a modern endoscope, and Figure 2 shows a schematic view of the cabinet according to the invention.

Referring firstly to Figure 1 there is shown -an endoscope 2 having an eyepiece 4 integrally provided within a control section 6 from which extends an insertion tube 8 terminating at a distal end 10.

Proximate the distal end 10 is a bending section 12 which can be manipulated and caused to assume an arcuate condition as shown in the Figure by means of control knobs 14. The insertion tube 8, bending section 12 and distal end 10 are all provided with a plurality of passages through which fluid can be extracted from the human whose innerds are being inspected. Fluid passes through these socalled channels and is expelled through a semi-disposable biopsy valve 16. The control section 6 includes a suction valve 18 and an air/water valve 20 which enables fluid extraction, and in certain circumstances an umbilical cord 22 may also be connected to the control section 6. Said umbilical cord can be used to provide a variety of additional features whose description is beyond the scope of this application.

The above description is provided merely to highlight the fact that potentially bacteria laden fluids may be drawn through the endoscope during an inspection or operative procedure, and it is therefore imperative that said endoscope is subjected to rigorous cleansing and disinfecting procedures.

A sterilising cabinet according to the invention is shown in Figure 2 by reference 30 and consists of a steel shell having a pair of side walls 32, 34 and a solid rear wall 36. A pair of steel doors (not shown in the interests of clarity) is hinged to the side walls and may be provided with a lock to secure the cabinet in a locked condition. Within the interior of the cabinet which is generally designated at 38 a number of endoscopes 40 are shown suspended by their control sections from support members (also not shown) which are ideally brazed onto or otherwise secured to the inner surface of the rear wall 36.

The interior 38 of the cabinet 30 is additionally defined by a base 41 an intermediate roof section 42 above which the cabinet extends to define a cavity 44 in which there is located an air filter 46 upstream of a fan 48 which draws ambient air into the cabinet through a grille 50 disposed in the uppermost region of the side wall of the cabinet. The fan has a sufficient power rating to both overcome the resistance to air passing through the filter unit and also to force air into the interior 38 of the cabinet through a conduit 52, which opens in the intermediate roof section 42, at a slight positive pressure differential with the ambient pressure externally of the cabinet. The doors of the cabinet are not manufactured to any specific tolerances nor provided with hermetic seals so that air can escape through the gaps between the doors and the side walls, the base, and the intermediate roof section. These gaps are however quite narrow so that they do present moderate resistance to the escape of air from the interior of the cabinet and allow a slight pressure differential to build up within the cabinet.

A compressor 54 is also provided in the cavity 44 which supplies filtered air directly through a manifold to a plurality of connectors 56. This compressor may be provided with its own air filtration system or may be draw filtered air downstream of the filter 46, but in any event the effect of the compressor is to drive filtered air through the channels within the insertion tubes of the endoscopes which are ideally connected thereto. There may also be provision for the connection of the umbilical cords of the endoscopes to connectors 56. This pressurised air effectively sterilises the channels by both depriving any extant bacteria in the channels of moisture.

The cabinet is additionally provided with four bactericidal or germicidal lamps 58 which ideally radiate ultra-violet energy within the cabinet interior when the doors are closed. The cabinet inner walls are either manufactured from a material such as stainless steel which reflects the UV radiation within the interior, or alternatively the inner surfaces of the cabinet interior may be painted or coated with a reflective substance. The reflection of the UV radiation within the cabinet reduces the shadow effects and aids the dispersion of the radiation, and thus the bactericidal action thereof on the air moving within the cabinet and also the surfaces of the endoscopes on which bacteria and other contaminants may proliferate.

In use, endoscopes are deposited in the cabinet interior and the doors are closed. Ideally a proximity sensor on the doors communicates with a control module (not shown) provided in the cavity 44 which on receipt of the alert activates the fan 48 and the compressor 54, and filtered air is thus driven into the cabinet and the channels of the endoscopes, if such are connected to the connectors 56. The air volumetric flow rate into the cabinet through the conduit 52 is greater than of the air exiting the chamber and therefore a slight positive pressure differential builds up within the cabinet. This substantially prevents the ingress of ambient air from outside the cabinet, and therefore the sterility of the atmosphere within said cabinet is ensured as only filtered air is present therein.

Additionally, after the doors are closed and a sterile atmosphere is created inside the cabinet, the UV lamps 58 are activated for a period of approx. 15 minutes, as this period has been calculated as optimum to achieve sterilisation without substantial energy consumption or significant degradation of any of the materials used in the construction of the endoscopes. During this period, the pressure within the cabinet and the UV illumination therein result in the conversion of a very small percentage of the oxygen present to ozone, which is a well known and powerful sterilising and disinfecting agent. Ozone is also a toxic gas, but the concentration levels reached within the cabinet never approach toxic levels, or can be controlled by exhausting the gases within the cabinet externally of the building in which the cabinet is located.

In addition to the control circuitry, there may be provided a validation system including sensors suitably disposed within the interior of the cabinet which detect whether filtered air has been continuously circulating within the interior, whether the compressed air has been delivered into the channels of the endoscopes, and whether the interior was illuminated successively a predetermined number of times with the UV radiation. If all the various sensed conditions were fulfilled, then the validation system may illuminate an indication means such as a green LED disposed on the external surface of the cabinet, and viewable by a user of said cabinet. In the event that all the relevant sterilisation procedures were not effected, then a red LED could be illuminated by the validation system.

Claims

1. A cabinet defining an interior in which articles to be sterilised can be stored, said cabinet having access means which can be opened and closed to allow access to said interior and being further provided with primary air flow creation means including filtration means by which the interior of the cabinet is supplied with filtered air substantially free from contaminants, said cabinet further allowing said air to escape from the interior to the ambient atmosphere, characterised in that the cabinet interior is provided with one or more bactericidal ultra-violet lights activatable when the access means are closed and in that the air flow creation means creates a positive pressure differential between the cabinet interior and the ambient atmosphere while the access means are closed such that there is substantially continuous flow of filtered air from the interior of the cabinet through the escape means and ambient air is prevented from ingress into said interior thereby during the operation of the air flow creation means.

2. A cabinet according to claim 1 wherein the activation of the air flow creation means is dependent on the closure of the access means.

3. A cabinet according to either claim 1 or 2 wherein the air flow creation means is activated continuously while the access means are closed.

4. A cabinet according to any preceding claim wherein the cabinet is provided with hanging means from which endoscopes can be suspended and is of a sufficient height to receive said endoscopes when hung from one of their ends.

5. A cabinet according to any preceding claim wherein the cabinet is provided a plurality of UV lights within the interior.

6. A cabinet according to any preceding claim wherein the access means constitute hinged doors provided in one of the walls defining the cabinet interior.

7. A cabinet according to claim 6 wherein the pressurised air within the cabinet escapes through the gaps between the hinged doors and the cabinet wall in which they are provided.

8. A cabinet according to any preceding claim wherein the pressure differential between the interior of the cabinet and the ambient surrounding atmosphere is approximately +15 Pascals.

9. A cabinet according to any preceding claim wherein the air flow creation means and filtration means is provided in an upper portion of the cabinet and delivery of filtered air is effected downwardly into the interior of said cabinet.

10. A cabinet according to any preceding claim wherein the cabinet further comprises means for generating a secondary flow of filtered air delivered to a plurality of connectors which allow for connection of apparatus having hollow tubular portions and through which air can be driven by said secondary air flow creation means when said apparatus is connected thereto.

11. A cabinet according to claim 10 wherein the secondary air flow generation means communicates with the primary air flow creation means and derives its air therefrom.

12. A cabinet according to claim 10 wherein the secondary air flow generation means comprises a secondary air compressor including filtration means which drives filtered air through the connectors into the apparatus connected thereto.

13. A cabinet according to any of claims 10, 11 or 12 wherein the connectors are adapted for connection to distal ends of endoscopes.

14. A cabinet according to any preceding claim wherein the surfaces of the cabinet interior at least partially reflect the UV light shone within said interior.

15. A cabinet according to any preceding claim wherein the interior walls of the cabinet and the access means are manufactured in a stainless steel.

16. A cabinet according to claim 2 and any claim dependent thereon wherein sensor means are provided in the cabinet to detect the closure of the access means, said sensor means communicating with the air flow creation means to activate same when said access means are closed.

17. A cabinet according to any preceding claim wherein the UV light or lights are activated intermittently while the access means are closed.

18. A cabinet according to claim 17 wherein the UV light or lights are activated intermittently for periods of 15 minutes.

19. A cabinet according to any preceding claim wherein the cabinet is provided with internal sensors which detect the operation of the UV lights and communicate with a validation system which further includes indication means visible externally of the cabinet by which a user can immediately determine whether the UV light of lights were operative while the access means were closed, and thus whether the apparatus within the cabinet has been effectively sterillsed.

20. A cabinet according to any preceding claim wherein the access means is capable of being locked.

21. A cabinet according to any preceding claim wherein the filtration means includes a High Efficiency Particle Air (HEPA) filter.

22. A cabinet according to any preceding claim wherein the cabinet is provided in a trolley configuration so that it is mobile.

23. A method of sterilising apparatus stored within a cabinet having access means which allow access to the interior of the cabinet and permit the apparatus to be deposited and removed therefrom comprising the steps of driving air filtered of bacteria and contaminants into the cabinet interior and simultaneously shining bactericidal ultra-violet light in said interior while the access means are closed.

24. A method according to claim 23 wherein the air is driven into the cabinet so as to establish a positive pressure differential between the cabinet interior and the ambient pressure.

25. A method according to either of claims 23, 24 wherein the UV lights within the cabinet are operated intermittently.

26. A method according to any of claims 23-25 wherein the method further includes the step of sensing the operation of the UV lights and performing a validation based on the time said UV lights were activated and the time since the cabinet was previously open to the ambient atmosphere, said cabinet having indication means exteriorly thereof differently activated depending on the success or failure of the validation by which a user can assess whether apparatus within the cabinet has been effectively sterilised.

27. A method according to any of claims 23-26 including the further step of driving air filtered of bacteria and contaminants through the interior of apparatus within the cabinet as well as over the exterior of said apparatus.