WO2014024118A1

WO2014024118A1 - Device, assembly and method for maintaining sterility

Info

Publication number: WO2014024118A1
Application number: PCT/IB2013/056408
Authority: WO
Inventors: Katiusa Da Ros; Claudio Tonon; Luigino Granziera; Alessandro DONADON
Original assignee: Irinox S.P.A.
Priority date: 2012-08-06
Filing date: 2013-08-05
Publication date: 2014-02-13
Also published as: ITPD20120241A1

Abstract

The present invention relates to a device (1) for maintaining sterility of medical substrates, such as surgical/dental systems or implements. Such device delimits a treatment compartment (2) for receiving the sterilised medical substrate and comprises, functionally connected to said compartment (2), freezing means (4) and air ionisation means (6) for preserving the asepsis. The invention further relates to a method for maintaining the asepsis.

Description

DESCRIPTION

"DEVICE, ASSEMBLY AND METHOD FOR MAINTAINING STERILITY"

FIELD OF APPLICATION

[0001] The present invention relates to a device and a method for maintaining sterility of a medical substrate, and to an assembly comprising such a device.

PRIOR ART

[0002] By definition, a substrate is considered "sterile" when it is substantially 100% free of vital microbial agents. In particular, the technical standard UNI EN 556- 1:2002 establishes that, in order to state that the substrates can legitimately be regarded as sterile, the probability that one of these substrates is not so in practice must be of a single event in a million.

[0003] The primary goal of a sterilization process is therefore to inactivate microbiological contaminants on certain substrates, for example on instruments for surgical use.

[0004] A further problem, however, concerns the subsequent maintenance of the sterilization.

[0005] The systems used to date, which for example provide for enveloping the substrate to be maintained sterile, are far from producing satisfactory results; in fact, the permanence of condensation in the enclosures, the formation of air pockets, the accidental tearing of the envelopes, the inadequate microclimate and microbial conditions in the storage environments are just a few examples of the most frequent drawbacks that strongly affect the preservation of asepsis. In addition, for an object to be enveloped, it must fall within predefined size ranges.

DISCLOSURE OF THE INVENTION

[0006] The present invention therefore falls within this context, aiming to provide a substantially automated device and process able to greatly simplify the maintenance of the sterilization of a substrate.

[0007] In fact, the device described, and the method implemented by it, are proposed as ancillary instrumentation for traditional sterilization equipment (e.g. autoclaves), so that the actual sterilization should not be repeated daily, for example on the whole Instrumentation. This results in a significant energy, operational and logistical saving.

[0008] According to a further advantage of the' present invention, the device and the method described are suitable for ensuring, in all possible conditions in which the sterilization activity - which involves intrinsic criticality - must be carried out, an adequate level of organizational management that can this make use of technological and structural aids matching the assistance needs of health facilities users in an environment that does not expose workers to occupational hazards, and that of course safeguards the health and safety of each patient.

[0009] According to a further advantageous aspect, the device and the method object of the present invention allow to drastically simplify the complex phases of a correct sterilization, allowing these phases to also be carried out by unskilled personnel or personnel specially trained for the purpose.

[0010] The traditional sterilization process in fact includes a series of consecutive tasks of varying complexity, so there is no doubt that the rotation of tasks and activities that occur in health' facilities is one of the most frequent causes of failure. The best way to reduce mistakes is to encode and mechanize the execution of many of these activities.

[0011] According to a further aspect of great advantage, the device and the method above have been clinically tested to ensure 100% maintenance of the sterility of substrates up to clinical use, in compliance with UNI EN ISO 11607 and EN ISO 11607 -1 - 2.

[0012] Furthermore, since the maintenance of the sterilization is not regulated in detail from a regulatory point of view, if not in relation to_ the technical effect that must be reached, the device and method described are proposed in full as a reference standard for maintaining the asepsis.

[0013] Advantageously, the cryogenic preservation (below - 15°C, preferably less than or equal to -20°C and in particular less than or equal to -30°C, advantageously greater than or equal to -50°C) for a potentially indefinite period of time, at least in principle, allows an accurate control of bioburden, understood as determination of the population of vital microorganisms present on a substrate subjected to sterilization.

[0014] Furthermore, the investment cost for the purchase of the present instrumentation is amortized in a short time by virtue of the drastic reduction of the cycles in the autoclave, which can be run at full load thanks to the possibility of sterile storage and which does not need further sterilization at the time of use of the substrate, for example to have greater safety at the time of use of the materials. Moreover, the ease of management of the sterilized articles is also added, as they are no longer handled and can be managed more simply even by paramedics .

[0015] According to a further advantageous aspect, with the invention described the water present or retained by the medical substrates (for example organic materials) does not form macro-crystals but crystal structures of reduced or in any case contained dimensions.

[0016] In fact, the presence of macro-crystals would impair the functionality and the molecular stability of the substrate, especially by virtue of the structural alterations that would reduce the quality irreparably.

[0017] Therefore, the protocol described allows the preservation of the morphological properties of materials subjected to the process or introduced in the equipment described below.

[0018] The above objects are achieved by a device according to claim 1, by an assembly according to claim 12, and by a method according to claim 16. The dependent claims describe preferred embodiment variations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The technical features of the invention, according to the above objects, are clearly found in the contents of the claims below and the advantages of the same will appear more clearly from the following detailed description, made with reference to the annexed drawings, which show one or more purely exemplifying and non- limiting embodiments thereof, in which:

[0020] - Figure 1 shows a device of the present invention, according to a possible embodiment, in which the door for closing the compartment of the treatment is in an .open- position; and

[0021] - Figure 2 shows a simplified diagram of a steam compression refrigeration circuit of the freezing means of a device according to a preferred embodiment of the invention.

DETAILED DESCRIPTION

[0022] The object of the present invention shall now be described in detail, with the aid of the annexed drawings .

[0023] With reference to the figures above, reference numeral 1 denotes, in its entirety, a device for maintaining the sterility of medical substrates.

[0024] According to an embodiment of particular advantage, such a device 1 forms an assembly with a device for the sterilization of a medical substrate.

[0025] In other words, device 1 described below constitutes a complement to the apparatuses which, on the contrary, are suitable to cause the actual sterilization of the medical substrate, but which are unsuitable to maintain it for long periods.

[0026] According to a particular embodiment, the sterilization device works with wet heat, and is preferably an autoclave.

[0027] According to a further particular embodiment, the sterilization device works with plasma gas, and is preferably a plasma gas autoclave.

[0028] By way of a non limiting example, in the present description the term "medical substrate" shall mean one or more of the entities selected from biological tissues ( cryobiology) or prosthesis implantable in a sub ect/patient , surgical or operating room instruments such as knife or scalpel handles, scissors, curettes, forceps, needle holders, mirrors, suture needles, retractors, catheters or any of the implements that make up surgical or dental instruments, and in general medical-surgical aids.

[0029] According to an embodiment, the medical substrate can be a dental impression, especially of the type comprising alginate and water, which inherently undergoes volumetric deformation due to thermal variations, but that nevertheless proves to be particularly convenient with the system described.

[0030] The maintaining device 1 delimits a treatment compartment 2 for receiving the sterilized medical substrate.

[0031] Therefore, the treatment compartment forms a sufficiently large cavity for housing the substrate, and preferably a plurality of such substrates.

[0032] According to the embodiment shown in Figure 1, the medical substrates can be rested on a bottom wall 16 of device 1 which inferiorly delimits the treatment compartment 2, and/or on a support or tray 18 placed in the compartment at a certain height from the bottom wall.

[0033] According to an advantageous embodiment, the support comprises a plurality of strips or rods 46 reciprocally spaced apart so as to delimit spaces 48 suitable to ensure air circulation and/or an even distribution of cold and, optionally, heat.

[0034] Advantageously, the support or tray 18 can be reversibly engaged in the treatment compartment 2, whereby it can be fitted/removed from the compartment as needed .

[0035] Such a compartment 2 is optionally accessible through an access opening 28, through which the medical substrates are placed in device 1, or extracted from the latter .

[0036] According to a preferred embodiment, such a tray 18 can be placed at different heights in the treatment compartment .

[0037] In particular, the side edges 20, 22 of the treatment compartment can be provided with a plurality of vertically spaced fixed supports 24, or provided with guides that can be moved close to/away from the bottom wall 16, for example, to diversify the distribution of the medical substrates in the treatment compartment depending on the steric dimensions thereof.

[0038] According to the embodiment shown in Figure 1, device 1 comprises a device enclosure 26 which encloses the treatment compartment 2 and which preferably frontally delimits the access opening 28. Preferably, such an enclosure is at least partially insulated so as to isolate the treatment compartment.

[0039] For example, the device enclosure 26 is associated with a support base 42, which in the embodiment shown is a base that can be rested on a support surface which^' then therefore acts as a base.

[0040] Advantageously, connected and movable relative to the device enclosure 26 there may be provided a closing door 30 suitable to at least partially overlap the access opening, preferably so as to hermetically or sealingly close the treatment compartment. For example, the closing door is rotatable relative to a vertical rotation axis X.

[0041] According to a preferred embodiment, interposed between the abutment surfaces of the door and of the device enclosure there are preferably provided sealing means 32, such as a seal, suitable to be pressed when the door is moved towards a closed position. This ensures the above seal of the compartment.

[0042] For example, the sealing means 32 may be placed peripherally to an inspection window 34 of the. treatment. compartment 2, inserted in the closing door 30.

[0043] Optionally, device 1 is provided with magnetic closing means arranged in a position opposite to the hinge zone of the closing door 30 so as to keep it in a closed position and, where provided, so as to compress the sealing means 32.

[0044] Functionally connected to the treatment compartment 2, device 1 comprises freezing means 4 and air ionisation means 3 for preserving the asepsis.

[0045] The freezing means are adapted to remove heat from the treatment compartment 2. The ionisation means 6 are adapted to sanitise the treatment compartment 2.

[0046] In other words, the freezing means 4 and the ionisation means 6 cooperate with each other and interact with the treatment compartment 2 to maintain sterility, and thus preserve the microbiological purity of the medical substrate.

[0047] From a careful experimental analysis, in fact, it has been found that the ionisation means are not per se sufficient to maintain the cavity of device 1 sterile since the maximum efficiency attainable by such means does not ensure the total 100% elimination of vital microbial agents.

[0048] Therefore, it has been seen that the ionisation means 6 synergically interact with the freezing means 4 to obtain a sterile environment, permanent in principle, from which material or implements can be taken if necessary.

[0049] In the present description, the terms "ionisation" , "sanitization" and "ozonation" will be used in a substantially interchangeable manner, by such terms meaning the elimination or reduction of the spreading of bacterial agents and allergens by air.

[0050] In fact, the term "ionisation" usually means an alteration of the connectivity or of electronic charges of molecules that make up air, in order to generate ions and radicals which carry out a sanitising action. During such an operation, through the recombination of the radicals there can be "ozonation", i.e. the formation of ozone, by virtue of the creation of covalent bonds, between atoms or molecular oxygen radicals. The "sanitization" of air can be achieved both by virtue of the above ozonation/ionisation and thanks to a mist of liquid disinfectant compounds into the air which allows the reduction or the elimination of bacterial colonies and their proliferation.

[0051] The present invention comprises an ionisation according to any of the preceding definitions.

[0052] Preferably, the freezing means 4 are sized to maintain in the treatment compartment 2 a temperature— below -15°C, preferably equal to or below -20°C, even more preferably equal to or below -30°C. According to an advantageous alternative embodiment, the above temperature value is equal to or above -50°C.

[0053] For such temperature values, in fact, it has been possible to find the optimum between energy use and asepsis. In fact, the above temperatures are low enough to provide an environment in which bacterial agents cannot survive or proliferate, but high enough not to require a continuous operation of the freezing means.

[0054] Advantageously, the freezing means are of the latest generation, as they have a sufficiently high cooling power to allow rapid cooling of the medical substrate at least at one of the above temperatures, and preferably in the range between -20°C and -50°C, preferably between - 20°C and -40°C, advantageously between -15°C and -40°C.

[0055] In other words, the freezing means 4 are sized so that device 1 for maintaining sterility can operate in cooling as a quick temperature reducer.

[0056] In the present description, the term "rapid cooling" is understood to mean a lowering of the temperature of the medical substrate which occurs, depending on the starting temperature and/or on the heat capacity of such a substrate, in sufficiently short times to prevent a rise of the temperature in the treatment compartment 2 above -15°C (and preferably above -20°C) .

[0057] For example, the cooling is considered "rapid" if it occurs in less than 45 minutes since the introduction of the medical substrate in the treatment compartment (such as a starting from a starting temperature of the substrate of about 90-100°C, if the substrate is sterilised in a wet heat autoclave) , preferably less than 30 minutes, advantageously less than 20 minutes, optionally higher than 5 minutes from said introduction.

[0058] According to a preferred embodiment, the freezing means 4 consist of at least one steam compression refrigeration . circuit which comprises at least one evaporator 8, one compressor 9 and one condenser 11 for performing a refrigeration cycle of a heat exchange gas. A simplified diagram of this circuit is shown in Figure 2, where reference numeral 13 designates a lamination valve placed between condenser 11 and evaporator 8.

[0059] Advantageously, the evaporator is in thermal contact with the treatment compartment.

[0060] For example, referring to the embodiment in figure 1, such an evaporator 8 is placed at the bottom wall 16. A further embodiment (not shown) provides for its placement at a back wall 36 of the treatment compartment, opposite to the access opening 28.

[0061] Advantageously, as shown ^'in Figure 2, the steam compression refrigeration circuit which constitutes the freezing means 4 comprises a by-pass branch 19 to short- circuit the output of compressor 9 at the inlet to evaporator 8. The passage of the heat exchange fluid in the by-pass branch 19 is permitted by closing a first valve 15 and opening a second valve 17, arranged upstream of the by-pass branch and in the by-pass branch, respectively. By opening the by-pass branch 19, the hot gas in output from the compressor is sent to the evaporator. This is used to perform quick defrosting of the evaporator. The speed of the defrosting operation is intended to minimise the time periods in which the treatment compartment 2 cannot be cooled, thus avoiding significant temperature increases inside the treatment compartment.

[0062] According to a particularly advantageous embodiment, device 1 comprises management and control means 10 operatively connected to the freezing means 4 and optionally to the ionisation means 6. Preferably, the management and control means comprise at least one programmable logic controller PLC or a microprocessor.

[0063] In this way, the operation of the device is substantially automated, and with an extremely high level of accuracy.

[0064] Preferably, the management and control means 10 comprise safety means set to prevent a rise in the temperature in the treatment compartment 2 to more than - 15°C, preferably more than -20°C.

[0065] In fact, since a rise in the temperature above such values would imply a risk of losing the sterility of the medical substrate, the present device was specially designed to avoid this condition.

[0066] According to a preferred embodiment, if an abnormal rise in the temperature could not be avoided due to a malfunctioning of the freezing means or due to the closing door left ajar/opened, the above device 1 might also report the situation of potential danger.

[0067] In this regard, an alternative embodiment may provide that the safety means may be functionally connected to alarm means, such as acoustic or visual, to send an alarm signal in case of anomalies. Preferably, the alarm devices comprise a light source, such as LEDs, and/or a siren.

[0068] According to an advantageous embodiment, the management and control means 10 are operatively connected to thermometric detection means 12 of the treatment compartment 2, e.g. a thermocouple, only schematised in the figure. Preferably, the freezing means 4 are controlled on the basis of the values acquired by the thermometric detection means 12. [0069] In particular, since the freezing means are advantageously connected to the management and control means (such as shown by the dashed line 38), as thermometric detection means 12 are (dashed line 40), the verification of temperature values takes place in real time, and the activation of the freezing 4 occurs accordingly in a controlled manner to maintain safe conditions. For example, the above operations can be carried out by a thermostat, preferably integrated into the management and control means.

[0070] Making a practical example, if sterilised instruments are taken from an autoclave when still warm, and inserted into the treatment compartment, with the verification system described above the present device is able to avoid the rising of the temperature above the threshold.

[0071] According to a further embodiment, the management and control means 10 comprise activation means of the freezing means, with which the personnel in charge can interact in order to subtract heat from the treatment compartment .

[0072] Making a further practical example, this embodiment provides for the activation of the freezing means to be controlled by the user/employee, such as by means of a button, preferably following the introduction of new medical substrate inside device 1.

[0073] Preferably, the activation means are timed, so that the subtraction of heat from the compartment ends after a predefined time and the temperature can then be maintained steady up to the withdrawal of the substrate.

[0074] According to an embodiment (not shown), the ionisation means 6 are inserted into the treatment compartment 2.

[0075] According to a further embodiment, device 1 delimits a separate technical compartment 14, which communicates fluidically with the treatment compartment 2, in which the ionisation means 6 are at last partially housed.

[0076] In this way, the ionisation means 6 are housed in an environment other than that in which the medical substrates are located and taken, although the ionised air may nevertheless flow towards the latter.

[0077] For example, the separation between the above compartments is via a partition wall 44, preferably joined at the side edges 20, 22. Optionally, such a partition wall 44 can be provided with slots (not shown) to ensure the fluid connection.

[0078] Preferably, device 1 comprises ventilation means for the creation of a forced air circulation between the technical compartment 14 and the treatment compartment 2. Optionally, the ventilation means are suitable to create a forced air circulation only in the treatment compartment 2, in order to affect the freezing, means with the created air flow.

[0079] While the ventilation means are not shown in the figure, the air flow caused by them is schematised by the four arrows mutually arranged head-to-tail at reference numeral 50. Preferably, the ventilation means create an air flow in a clockwise direction, for example in view of the access opening 28 (as shown in the figure) or in a direction orthogonal to such a view.

[0080] In particular, the ventilation means comprise at least one centrifugal fan placed in communication with the treatment compartment.

[0081] According to an alternative embodiment, device 1 comprises heating means of the treatment compartment 2 suitable for being activated to raise the temperature of the substrate to a desired value, preferably to a value of about 35-39°C, according to a controlled timeline. Even more preferably, the desired temperature value is substantially 37 °C, corresponding to the body temperature .

[0082] By way of example only, by controlled timing it is meant that the heating of the compartment and of the items contained therein does not occur by simply reaching the thermal balance with the surrounding environment, but so as to make the substrate available at its use, for example at the beginning of a surgery or a step thereof.

[0083] In other words, the heating means are connectable to the management and control means to perform a predetermined temperature ramp, and advantageously to provide the instrumentation at a temperature value significantly higher than the environmental value, already suitable for performing a surgery or a medical procedure.

[0084] In fact, while surgical instruments can be used at room temperature (about 20 °C), this temperature may be variable depending on the season, even in indoor environments such as an hospital or a surgery, by virtue of air-conditioning or heating systems acting thereon. This leads to a non-optimal use of the medical substrate, which would create a thermal shock to the patient.

[0085] The present invention further relates to a method for maintaining sterility; preferably, but not necessarily, such a method is implemented by device 1 and the assembly described above.

[0086] As a result, even where this is not explicitly indicated, some embodiments of the method comprise all steps described, in structural or functional terms, in relation to device 1 or to the related asepsis assembly. 10087] 7t is however possible to. implement such a method with other devices having all the essential features of the procedure.

[0088] Such method comprises the steps of:

[0089] - providing one or more sterilised medical substrates;

[0090] - arranging a treatment compartment 2, suitable to be isolated from the outer environment;

[0091] - arranging said one or more sterilised medical substrates in the treatment compartment 2 and isolating said compartment from the outer environment;

[0092] - maintaining the sterility of the substrate (or plurality of them) inside the treatment compartment through a lowering of the temperature of the compartment and an ionisation of the air in the compartment.

[0093] Accordingly, as discussed above, the maintaining step comprises a preservation of the sterilisation of the medical substrate. Such a method is based on the synergic interaction between ionisation and low/very low temperatures to preserve sterility.

[0094] Preferably, the sterility maintaining step comprises a rapid cooling step of the medical substrate to a temperature below -15°C, preferably equal to or under below -20°C, advantageously equal to or below -30°C, optionally equal to or over -50°C.

[0095] Advantageously, the rapid cooling step is conducted whenever one or more sterilised medical substrates with temperatures above 0°C are inserted in the treatment compartment .

[0096] Advantageously, the sterility maintaining step comprises a step of maintaining the substrate to a temperature below -15°C, preferably equal to or below - 20°C, advantageously equal to or below -30°C, optionally equal to or over -50°C. In this temperature maintaining step, a cooling power is required which is lower than that required in the rapid cooling step.

[0097] Preferably, the step of maintaining the substrate to a temperature below -15°C is carried out after a rapid cooling step of the medical substrate.

[0098] According to an alternative embodiment, the sterility maintaining step comprises a step of thermometric detection of the temperature inside the treatment compartment and a step of adjusting the cooling power according to the temperature values detected for maintaining the temperature within the treatment compartment below -15 °C.

[0099] According to a further embodiment, the sterility maintaining step comprises a step- of forced circulation of a flow of ionised air within the treatment compartment 2.

[00100] Preferably, the step of forced circulation of a flow of ionised air within the treatment compartment 2 is carried out at predefined time intervals concurrently with the other operating steps of the method. In particular, such a step of forced circulation of ionised air - which corresponds to the ionisation step of the treatment compartment 2 - can be carried out continuously to ensure an ongoing sanitisation of the treatment compartment 2.

[00101] Advantageously, the method can comprise a heating step of the substrate to predefined temperature values according to a controlled timeline. For example, the heating step can take place at a temperature of about 25-29°C. In particular, the heating is conducted to bring the medical substrates to room temperature, and preferably to the body temperature of the patient upon which these substrates are used, for example, to 37 °C.

[00102] Advantageously, during the step of heating the substrate, a flow of ionised air is forcedly circulated within the treatment compartment 2.

[00103] According to a particular embodiment of the invention, the method comprises at least one step of disinfection of the treatment compartment^' 2 to make the compartment aseptic and sanitised. Preferably, such a disinfection step is conducted before inserting the medical substrates inside the compartment and optionally at predefined time intervals.

[00104] Advantageously, the sterilised medical substrates can be placed in the treatment compartment 2 within one or more closed protection enclosures or without protection enclosures. By protection enclosures it. is meant, for example, the envelopes inside which sterilised medical substrates are traditionally placed'.

[00105] The effectiveness of the device and method according to the invention for maintaining sterility was confirmed through verification tests. The tests run have allowed the effectiveness to be certified at least for a period of 3 months .

[00106] The tests were conducted by measuring the bioburden on metal surfaces subjected to artificial contamination, subsequent sterilisation in autoclave and finally, maintenance of sterility through the device and the method according to the invention. The tests were conducted on both enveloped surfaces and on non enveloped surfaces.

[00107] The sterilisation of metal surfaces was conducted in . autoclave with a validated procedure using a chemical and biological sterilisation indicator.

[00108] The treatment compartment 2 of device 1 was subjected to disinfection using a disinfectant for surfaces at time 0 and subsequently every seventh day from the beginning of the test. The surfaces were kept at a temperature equal to -30°C and with a ionisation system of the inside air activated according to the following time scheme: operating time of 50 minutes, pause time of 310 minutes. To simulate normal use conditions, every 48 hours the treatment compartment 2 was opened for 30 seconds. The microbiological tests were performed at times 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84 days. The surfaces examined (enveloped and non enveloped) were randomly taken from the compartment, immersed in a known volume of eluent, and finally mechanically agitated to facilitate the suspension of any microorganisms present. The growth of any microorganisms was evaluated both through direct culture of the eluent in liquid medium, and by vacuum filtration and subsequent culture of solid medium of the filter. The bacteriological tests were conducted both at 37 °C and at 20 °C, in order to highlight both the growth of mesophilic bacteria, indicating anthropic contamination, and of psychrophilic bacteria, indicating environmental contamination. For each sampling point, swabs of the surfaces of the treatment compartment were collected before subjecting them to disinfection again.

[00109] The microbiological tests were performed at times 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84 days. The bacteriological tests were conducted both at 37 °C and at 21°C. For evaluating the growth, the bacterial cultures were observed at 3 and 5 days of growth, the fungi cultures at 5 and 9 days of growth, the mycobacteria cultures at 21 days of growth in a CO₂ incubator .

[00110] In all points examined, the evaluations performed were negative, in the growth and incubation conditions provided. The parallel control tests gave positive results. The tests conducted have therefore fully confirmed the effectiveness of the device and method according to the invention in maintaining sterility at least for a period of 3 months.

[00111] A man skilled in the art may make several changes or replacements of elements with other functionally equivalent ones to the embodiments of theabove device, assembly and method in order to meet specific needs.

[00112] Also such embodiments are included within the scope of protection as defined by the following claims.

[00113] Moreover, each alternative embodiment described as belonging to a possible embodiment may be implemented independently of the other alternative embodiments described .

Claims

1. Device (1) for maintaining ^" the sterility of medical substrates, such as surgical/dental systems or implements, which delimits a treatment compartment (2) for receiving at least one sterilised medical substrate and which comprises, functionally connected to said compartment (2), freezing means (4) and air ionisation means (6) to preserve the asepsis, said freezing means being adapted to subtract heat from said treatment compartment (2), said ionisation means (6) being adapted to sanitize said treatment compartment (2) .

2. Device according to claim 1, wherein the freezing means (4) are sized to maintain a temperature in the treatment compartment (2) below -15°C, preferably equal to or below -20°C, advantageously equal to or below - 30°C, optionally equal to or higher than -50°C.

3. Device according to claim 1 or 2, wherein the freezing means (4) consist of at least one steam compression refrigeration circuit which comprises at least one evaporator (8), one compressor and one condenser for performing a refrigeration cycle of a heat exchange gas .

4. Device according to claim 3, wherein said ^' evaporator (8) is in thermal contact with the treatment compartment (2) .

5. Device according to claims 2 and 3, wherein the freezing means (4) are sized to supply a sufficiently high cooling power to allow a quick cooling of the medical substrate at said temperature.

6. Device according to one or more of claims 2 to 5, wherein the freezing means (4) are sized so that the device (1) for maintaining sterility can operate in cooling as a blast chiller.

7. Device according to any of the previous claims, comprising control and management means (10) operatively connected to the freezing means (4), said control and management means (10) comprising safety means suitable for preventing a raising of the temperature in the treatment compartment (2) to over -15°C, preferably over -20°C,

8. Device according to claim 7, wherein the control and management means (10) · are operatively connected to thermometric detection means (12) of the treatment compartment (2), said freezing means (4) being controllable on the basis of values acquired by the thermometric detection means (12).

9. Device according to any of the previous claims, which delimits a separate technical compartment (14), which communicates fluidically with the treatment compartment (2), in which the air ionisation means (6) are at last partially housed.

10. Device according to claim 9, comprising ventilation means, for the creation of a forced air circulation between the technical compartment (14) and the treatment compartment (2) .

11. Device according to any of the previous claims, comprising heating means of the treatment compartment (2) suitable, for being activated to raise the temperature of the substrate to a predefined temperature value according to a controlled timeline.

12. Asepsis assembly comprising a device for the sterilisation of a medical substrate and a device (1), accessory thereto, for maintaining sterility according to any of the previous claims.

13. Assembly according to claim 12, wherein said sterilisation device is an autoclave.

14. Assembly according to claim 13, wherein said sterilisation device is with wet heat and preferably is a steam autoclave.

15. Assembly according to claim 13, wherein said sterilisation device is with plasma gas and preferably is a plasma gas autoclave.

16. Method for maintaining sterility of medical substrates comprising the steps of:

- providing one or more sterilised medical substrates, such as surgical/dental systems or implements;

- arranging a treatment compartment (2), suitable to be isolated from the outer environment;

arranging said one or more sterilised medical substrates in said treatment compartment (2) and isolating said compartment (2) from the outer environment;

- maintaining sterility of said substrate within said treatment compartment by decreasing the temperature of said compartment and ionising the air in said compartment .

17. Method according to claim 16, wherein the sterility maintenance step comprises a rapid cooling step of the medical substrate to a temperature below -15°C, preferably equal to or under below -20 °C, advantageously equal to or below -30°C, optionally equal to or over - 50°C.

18. Method according to claim 17, wherein the sterility maintenance step comprises a step of maintaining the substrate at a temperature below -15°C, preferably equal to or below -20°C, advantageously equal to or below - 30°C, optionally equal to or over -50°C, said step of maintaining the substrate to a temperature below -15°C being carried out after said step of quick cooling of the medical substrate.

19. Method according to one or more of claims 16 to 18, wherein the sterility maintaining step comprises a step of thermometric detection of the temperature inside the treatment compartment (2) and a step of adjusting the cooling power according to the temperature values detected for maintaining the temperature within the treatment compartment below -15 °C.

20. Method according to any of claims 16 to 19, wherein the sterility maintaining step comprises a step of forced circulation of a flow of ionised air within the treatment compartment (2) .

21. Method according to claim 20, wherein said step of forced circulation of a flow of ionised air within the treatment compartment (2) is carried out at predefined ti-me intervals concurrently with the other operating steps of the method.

22. Method according to any of claims 16 to 21, comprising a heating step of the substrate to a predefined temperature value according to a controlled timeline.

23. Method according to claim 22, wherein during said step of heating the substrate, a flow of ionised air is forcedly circulated within the treatment compartment (2).

24. Method according to one or more of claims 16 to 23, comprising at least one step of disinfecting the treatment compartment (2) adapted to make the treatment compartment (2) aseptic and sanitized.

25. Method according to one or more of claims 16 to 24, wherein said one or more sterilised medical substrates are placed in the treatment compartment (2) inside one or more closed protection enclosures.

26. Method according to one or more of claims 16 to 24, wherein said one or more sterilised medical substrates are placed in the treatment compartment (2) without protection enclosures.