Process and apparatus for sterilizing surgical instruments DESCRIPTION

The present invention relates to a process and an apparatus for sterilizing surgical instruments. In particular, the apparatus and the process of the invention allow to carry out the sterilization, by means of saturated steam and vacuum-drying, often with the alternation of the introduction of external air (the succession of air/vacuum pulsations is called washing in technical jargon), of surgical instruments packed inside containers or packaging and placed on an internal trolley.

It is known that the use of surgical instruments requires washing and disinfection / sterilization operations due to the use on multiple patients.

Traditional multi-stage procedures are known which involve carrying out washing, disinfection and sterilization in different phases and / or operating stations.

In procedures that include sterilization, the saturated steam transmits heat to the instruments and their packaging, which are at a lower temperature, generating condensation on them. The sterilization process normally begins with an initial vacuum phase and continues with a conditioning phase where vacuum and steam are alternated inside the chamber in order to eliminate the presence of air pockets as much as possible. After conditioning, the introduction of steam is maintained up to the value of the sterilization temperature (which commonly takes the name of "plateau") when the conditions reached are maintained for a certain period of time. At the end of the sterilization plateau, the condensation generated on the materials inside the chamber must be completely eliminated, causing a possible bacteriological regrowth. In practice, the sterilization process of surgical instruments determines the need for careful drying of the same instruments once washed.

A first drawback of known type sterilization systems is that the duration and intensity of the drying / washing phase are determined in a predetermined manner and usually these are the same for all the sterilization operations performed. In other words, with the techniques used up to now it is necessary to perform even excessive drying (resulting in an unjustified waste of resources) to ensure drying in all load conditions.

Another drawback that is encountered in such known types of equipment is that even for the sterilization phase, the duration and intensity are determined in a predetermined manner and usually are the same for all the operations performed. In other words, with the techniques used up to now it is possible that the resources necessary to sterilize the maximum load (which is commonly called "critical load") are used for all the different load conditions, but are oversized for lower loads, with consequent unjustified waste of resources even in this phase.

CN108524985A describes a disinfection control method which includes the steps of acquiring an image and a weight of an item to be disinfected placed in a disinfection chamber. According to CN108524985A, the disinfection procedure can be programmed on the basis of the image data and the weight of the item to be disinfected.

The present invention relates to an apparatus and a method intended for surgical instruments, which can be contained in containers of various types such as, for example, a container or other types of packaging or even positioned on trays, providing considerable advantages both from the point of view of the safety provided both by that relating to the optimization of the drying and washing process.

This result has been achieved, in accordance with the present invention, by adopting the idea of providing a process and an apparatus having the characteristics indicated in the independent claims. Other characteristics of the present invention are in the dependent claims.

A method and an apparatus di sterilizzazioneof surgical instruments in accordance with the present invention have improved characteristics of use, that is, they allow the most effective execution of the washing and drying steps, while guaranteeing in any case the achievement of an extremely high degree of safety.

Among the advantages of the present invention the following can be listed by way of non-limitative: the process and the apparatus allow to program and therefore optimize the final washing and drying process of the instruments before unloading from the sterilizer; the optimization of the washing and drying processes thus available determine a decrease in the times and resources used compared to the known technique, thus providing the possibility of directing the time and resources saved to other production and / or control activities, consequently increasing productivity and / or safety of the treatments performed; the use of the apparatus and the implementation of the process simultaneously increase the safety of sterilization and the productivity of the systems without entailing any additional difficulties on the part of the operators; the instruments treated with the apparatus and the process of the invention provide safety standards no lower than those guaranteed by the known technique. These and further advantages and features of the present invention will be better understood by every person skilled in the art thanks to the following description and the attached drawings, provided by way of example but not to be considered in a limiting sense, in which:

- Figs.l and 2 relate to a possible embodiment of an apparatus for the sterilization of containers or packages containing instruments to be processed, represented respectively in a front view (Fig.l) and in an enlarged detail (Fig.2) of the front view;

- Figs. 3, 4, 5, 6 show a possible embodiment of a mobile structure, or internal trolley, which is positioned inside the sterilization chamber to support the containers or packaging of the surgical instruments during the phases of vacuum, conditioning, sterilization and washing/drying, shown, respectively, in a front view (Fig. 3), in a side view (Fig. 4), in a top plan view (Fig. 5) and in a perspective view (Fig.6);

- Figs. 7, 8, 9, 10, 11 show a possible embodiment of a device for weighing the internal trolley according to the present invention, represented, respectively, in a plan view from below (Fig. 7) , in a perspective view from below (Fig.8), in a front view (Fig. 9), in a side view (Fig.10), in a plan view from above (Fig.11); and

- Fig. 12 is a block diagram illustrating a possible example of embodiment of a complete sterilization process carried out in accordance with the present invention;

- Fig. 13 is a diagram relating to the pressure trend over time of a possible example of implementation of a sterilization cycle;

- la Fig. 14 e uno schema in cui e rappresentata una camera di sterilizzazione con un relativo dispositivo per il vuoto.

- Fig. 14 is a schematic drawing in which a sterilization chamber is represented with a relevant vacuum device.

In this description the sterilization phases will be mentioned to represent the treatment performed on the surgical instruments, without indicating any additional phases of disinfection, sterilization, etc.

The surgical instruments to be sterilized, suitably packaged inside containers, packaging or as required by the state of the art, are arranged on a containment structure (2) which can be constituted, for example, by a trolley (2) with a series of adjustable levels for the support of the above objects as the one represented in the attached drawings.

Although in the present description and in some of the attached drawings it is assumed to support the instruments to be sterilized by means of the trolley (2), the present invention also finds application in sterilizers in which the instruments are inserted in trolleys of different conformation, on trays, or on any suitable means to support the instruments during sterilization.

The trolley (2) inside the sterilizer (1) represented in the drawings of the attached figures is formed by a series of shelves (20) adjustable in height and fixed to four uprights (21). For fixing to the uprights (21), the upper shelf is provided with four pins (23) intended to be received in corresponding seats (22) provided on the uprights (21). In particular, the pins (23) have a free end or head which has a larger section than the stem of the pin (23) and each of the uprights (21) is provided with a plurality of slotted holes (22) arranged in vertical succession in in order to allow the fixing of the upper shelf at different heights, also according to the size of the surgical instruments to be treated. The slotted holes (22) have a greater section placed above and shaped so as to allow the passage of the head of the pins (23) and a smaller section located at the bottom and shaped in such a way as to allow the passage of the stem of the pins (23) but not of the head. In its lower part the trolley has a series of wheels (33) that allow the translation of the same from a structure external support (or external trolley, not shown in the drawings), towards the inside of the chamber, where there is a weighing device

(3).

During the sterilization treatment, the trolley (2) is placed inside the sterilization chamber (10) provided in a sterilization apparatus (1) in which the various phases of the process are carried out, from the initial pre-vacuum up to drying. The attached figures schematically represent an example of an implementation of the sterilizer (1) in which two doors (11) and (12) for access and a command and control panel (13) are provided. The sterilizer can be made with single or double door.

Inside the chamber (10) the trolley (2) is placed on a platform (30) which is part of a weighing device or is otherwise connected to the same device. In particular, with reference to the drawings, the platform (30) has a substantially rectangular shape in plan and is equipped with at least one sensor (3) suitable for providing a value relating to the weight of the tray or basket (2) placed on the same platform (30).

The platform (30) of the illustrated example is formed by two side portions (31) which extend parallel to each other along the longitudinal edges of the platform (30) and which are joined by a central portion (32) raised with respect to the two side portions (31) so as to define a lower cavity in which the weight sensors (3) are arranged and acted, sensors which in the example illustrated are two in number.

The sensors (3) can consist of load cells or other convenient sensor suitable for providing a signal relating to the weight of a trolley (2) resting on the platform (30).

On the trolley (2), for example in correspondence with the lateral portions (31) of the platform (30), there can be provided support or translation elements, for example wheels (33), suitable for determining a correct positioning of the trolley (2) on the platform (30), that is, suitable for allowing the correct detection of the weight of the trolley (2) and of the instruments placed on it.

The sterilizer (1), which is the operating station in which the sterilization process takes place, is provided, in a manner known per se and therefore not described in detail, with means suitable for: exerting a suction in order to produce the vacuum inside the sterilization chamber, introducing steam into the sterilization chamber, introducing and sucking air into the same chamber. These means are not illustrated in Figs. 1-11, are represented by blocks in the diagram of Fig. 12 and represented only partially and schematically in Fig. 14.

Fig. 14 schematically shows a possible example of embodiment of the means (4) suitable for exerting a suction to produce the vacuum inside the chamber (10), chamber which is delimited by a jacket or external casing (14). These means comprise a vacuum pump (4) which is arranged and acts on a first duct (40) which is connected to the sterilization chamber (10) in an upstream end (41) and in the opposite end (42) placed downstream is provided with a drain outlet. On the duct (40) there are one or more means for interrupting the flow (43), consisting of or comprising electrically controlled valves.

In the example of Fig. 14 the pump (4) also acts on a second duct (44), which is connected at one end (45) to the sterilization chamber (10) and at the opposite end (46) to the first duct (40), in a point upstream with respect to the pump (4), i.e. in a point (46) such as to allow the pump (4) to suck into the second duct (44). On the second duct (44) there is a flow meter (5) capable of measuring the volume of the fluid that passes through the second duct (44). Also on the second duct (44) there are means for interrupting the flow (43), consisting of or comprising electrically controlled valves.

As will be described below, the pump (4) can suck from the chamber (10) through the first duct (40) or through the second duct (44) depending on the opening of the valves (43). When the fluid (air) is extracted through the second duct (44) the flow meter (5) can provide a value of its quantity, that is a value relative to the volume of air extracted from the chamber (10).

With reference to the diagram of Fig. 12, a possible embodiment of a process according to the present invention provides that initially (block A of Fig. 12) a trolley or other container (2) that supports the instruments to be sterilized is placed in the sterilizer (1), in particular inside the chamber (10) on the platform (30).

The process foresees that a weighing of the trolley (2) and of the instruments it contains is carried out, as indicated by block (B) of Fig. 12. The detection performed by the sensor (s) (3) provides a first value (P0) relating to the weight of all contents and the trolley (2).

At the same time as measuring the weight of the instruments and the trolley (2), the apparatus measures the volume (V0) occupied by the trolley (2) and instruments inside the chamber (10). For this purpose, the apparatus (1) uses the value of the volume of the air extracted from the chamber (10) after the introduction of the instruments, comparing it with the value of the volume of the empty chamber.

To determine the volume of the empty chamber (10), ie the volume of the chamber (10) without instruments inside, the air is sucked in until a predetermined value or “set point” is reached. The detection of the volume (V0) occupied by the trolley (2) and by the instruments it supports is performed by extracting the air from the "full" chamber until the same predetermined value used to determine the volume of the "empty" chamber is reached.

The detection of the volume (V0) occupied by the trolley (2) and instruments, is carried out at the beginning of the sterilization treatment, before the beginning of the alternating vacuum-steam pulsation phases which constitute the phase indicated with (D), i.e. washing.

The measurement of the volume occupied by instruments and trolley is performed by calculating the difference between the volume of the empty chamber and the volume of the extracted air when instruments and trolley are arranged in the chamber.

Preferably, the measurement is carried out using a line dedicated to this purpose (the second duct 44) because during the alternating vacuum-steam pulsation phases that characterize the washing phase (block D of Fig. 12) the flow meter (5) it could be damaged by the presence of saturated steam, i.e. provide data that are not sufficiently reliable. For this reason, it is preferable to use the second duct (44) which is dedicated to making the first vacuum, when measuring the volume.

The diagram of Fig. 14 is exemplicative and not exhaustive in the sense that it shows only the parts necessary to make the present invention understood and not all the other components that are known in the state of the art and provided in steam sterilizers are represented.

As previously indicated, to establish the volume value of the entire chamber, the system is calibrated by carrying out a measurement with an empty chamber, measuring the volume of air sucked in until a "set point" is reached, normally dictated by the characteristics of the vacuum pump and of the circuit (normally included, for example, between 30 and 40 mbar absolute). This represents a sort of reference “0” value with which the obtained measurements will be compared.

It is known that all sterilizers or autoclaves provide for an "empty" cycle that is carried out on a frequent basis (usually daily in the morning at the start of processing) to check the integrity of the same machine before it begins to perform treatment cycles. In the present case, the set value of the empty chamber volume can be linked to this cycle in order to always keep this reference value updated, which in this way will also take into account possible conditions of decay of the vacuum pump.

In accordance with the invention, when a sterilization cycle is started and the instruments and the relative trolley (2) or other container are placed inside the chamber (10), the pre-vacuum phase is carried out when the value up to the set pressure of the pump, beyond which it cannot go. The value, calculated precisely with the material inside the chamber (consisting of packaged medical instruments and trolley) is compared with the reference value obtaining the volume occupied by all materials, indicated with (V0) in Fig. 12.

The volume measurement value (V0) of the material in the sterilization chamber, combined with the weight value (P0) of the same material, allows to calculate the average density of the loaded material (indicated with p). In other words, at each sterilization cycle, the equipment (1) is able to use a "density" value, for example equal to p = P0 / V0. With this value it will be possible to identify some ranges to adapt the most correct cycle to the specific sterilization functions. By way of example, the management of the steam injection and vacuum creation ramps, the work thresholds of the various components (steam pressure available from the generator or cavity) and the duration of the cycles can be optimized. With reference to the block diagram of Fig. 12, the two measurements performed in phase (B) allow to obtain the density value (value p in phase C) to program the subsequent washing (block D) and drying (block E) phases according to the value obtained.

In the block diagram of Fig. 12, in which the initial start-up phase is indicated with (A) and the end of sterilization with (F), blocks (D) and (E) generally represent the washing and drying which are programmed on the basis of the density value (p) obtained (the condition of dependence of the programming on the detected density value is schematically represented by the arrow in a discontinuous line); it is necessary to specify that in detail the setting of these phases involves the programming of various parameters such as, for example, those indicated previously and schematically represented in the graph of Fig. 13, where an example of the pressure trend is shown (represented by the value of ordinate) with respect to time (represented by the abscissa value) for a further description of the sterilization process object of the invention. The temperature value has not been shown in the graph since it is not essential for the purposes of this description; in general, it is possible to state that the temperature trend is comparable to that of pressure, i.e. it follows an initial phase of sudden changes (corresponding to the pre - vacuum phase) until a plateau value is reached (indicated by the double arrow PL) in which it remains constant as well as the pressure. In practice, the “programming” of the sterilization cycle determines a variation in the steam injection and vacuum creation ramps, in the work thresholds of the various components, in the duration of the cycles, etc..

With reference to Figs. 12 and 13, when the sterilization cycle is started, once the trolley (2) has been positioned inside the sterilization chamber (10), the weight is measured (block B of Fig. 12 and circle B (P) of Fig. 13) in order to obtain the weight value (P0) of instruments and trolley (2).

At the same time, is executed the measurement of the volume (block B of Fig. 12 and circle B (V) of Fig. 13) in order to obtain the value of the volume (V0) occupied by instruments and trolley.

Obtaining the weight (P0) and volume (V0) values makes it possible to calculate the density (p) (phase C of Fig. 12), the latter value which allows to identify with good approximation the nature of the instruments to be sterilized and the most appropriate sterilization treatment. By way of example, a relatively high density value can identify the presence of instruments with a relatively high specific weight and therefore suitable for undergoing a more intense sterilization treatment, while a relatively low density value can identify the presence of instruments with a relatively low specific weight and therefore suitable for being subjected to a more delicate sterilization treatment. In other words, based on the calculated density value (p), the quantities of steam introduced into the chamber, the temperatures and pressures used for the washing and drying phases, the duration times of the entire treatment and its phases may vary, etc.

In practice, the subsequent phases identified by the blocks (D) and (E) of Fig. 12 and by the trend of the graph of Fig. 13 can be set according to the density value (p) presented by the instruments located in the chamber of sterilization, determining a sort of "adaptation" of the treatment according to the materials to be sterilized.

Subsequently, on the basis of the detected density values, the various phases foreseen by the sterilization treatment are carried out, i.e. an initial pre - vacuum phase, followed by an alternating series of steam injection, heating, up to the plateau (represented by the horizontal section indicated by the double arrow PF in Fig. 13), and the last phase which is the drying phase, which involves washing (vacuum-external air) to also cool the inside of the material (consisting of instruments and relative packaging wrapping) and bringing dry air.

Therefore, according to the process in question, or with the relative apparatus, it is possible to carry out a programming of all the sterilization phases at each treatment cycle specifically dedicated to the real characteristics of the material being treated, thus determining an optimization of the sterilization, with duration and intensity of the operative phases of the treatment calibrated in such a way as to be efficient and effective, i.e. able to limit as much as possible the consumption and the times necessary for the sterilization cycle while guaranteeing a high degree of sterility of the treated instruments.

As previously expressed, in the attached drawings some details have not been shown in detail, such as, for example, the connection and control devices between the aforementioned components; by way of example, the measurements made by the weighing means (3) or by the volume measuring means (5) of the chamber (10) are sent to a central unit (not described or illustrated) which, being connected at least to the means that compose the sterilization apparatus, can be delegated to the activation and control of the washing and drying phases in order to perform these operations automatically. Means for manual entry of commands may also be provided (for example a keyboard, a PC or control panel) for programming the weighing, washing, drying and central control unit means.

The details of execution can in any case vary in an equivalent manner in the shape, dimensions, arrangement of the elements, nature of the materials used, without however departing from the scope of the idea of the solution adopted or of the inventive concept and therefore remaining within the limits of the protection granted by the claims.