Sterilizing apparatus and method for medical instruments

Abstract: The present invention provides a sterilizing apparatus and a sterilizing method for medical instruments enabling easy sterilization of medical instruments in a short time. There are provided an electrolyzation device (2) which produces acidic electrolytic water (20a) as a sterilization liquid by electrolyzing electrolytic water (20) stored in an electrolytic cell (21), a sterilization bath (3) for storing medical instruments to be sterilized by the acidic electrolytic water, and a circulation device (4) which circulates the acidic electrolytic water between the electrolytic cell and sterilization bath thereby to sterilize the medical instruments.

Description: BACKGROUND OF THE INVENTION The present invention relates to a sterilizing apparatus and a sterilizing method for automatically sterilizing medical instruments such as endoscopes or the like with the use of oxidation water. The use of endoscopes has rapidly spread in recent years to inspect upper and lower alimentary canal such as the esophagus, stomach, etc. and the large intestine, etc., inviting an increase in the number of the endoscopic inspections carried out in each facility. In spite of this fact, however, every facility owns merely a few endoscopes due to the expensiveness. While the endoscopes finishing the day's service are cleaned and sterilized before kept in the depositary, the sterilization of the endoscopes cannot be said to be executed enough, because the number of inspections is increased, the facility possesses only a small number of endoscopes, in other words, the using number of times per one endoscope is increased, or due to time and labor problems. The endoscopes shared among patients are consequently not clean, resulting in a fear that germs and virus adhering to the endoscopes spread among the patients. The infection with the germs and virus has drawn particular attention lately in accordance with the increase of the inspecting number of times. JP-A-07116664 discloses a sterilizing apparatus comprising an electrolyzation device which has an electrolytic cell and produces acidic electrolytic water from brine. JP-A-07171101 discloses a sterilizing apparatus for endoscopes which produces and uses electrolytic water as a disinfectant. Any sterilizers for the endoscopes in the market use sterilization liquid or disinfectant including liquid medicine, e.g., a glutaraldehyde formulation solution, which require time not only to soak the endoscopes in the sterilization liquid, but to rinse the sterilization liquid, that is, several tens minutes in total. The endoscopes shared among the patients cannot be sterilized simply in a short time by the above conventional sterilizers. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sterilizing apparatus and a sterilizing method enabling easy sterilization of medical instruments in a short time. In accomplishing these objects, the present invention provides a sterilizing apparatus for medical instruments according to claim 1. By the construction of the present invention, the electrolyzation device produces in the electrolytic cell the acidic electrolytic water for the sterilization of the medical instruments set in the sterilization bath. On the other hand, the circulation device supplies the acidic electrolytic water produced at the electrolytic cell to the sterilization bath, and also returns the acidic electrolytic water from the sterilization bath to the electrolytic cell, thus circulating the acidic electrolytic water between the electrolytic cell and sterilization bath thereby to sterilize medical instruments. When the acidic electrolytic water is used as a disinfectant as above, since the acidic electrolytic water remaining on the surface of the sterilized medical instruments is changed to neutral water in accordance with the lapse of time, the sterilizing apparatus of the present invention eliminates the necessity for rinsing the disinfectant after the sterilization although conducted in the prior art, achieving the sterilization in a short time. Moreover, the sterilizing apparatus enables easy sterilization of medical instruments, because it is enough to simply put the medical instruments in the sterilization bath. When the acidic electrolytic water is circulated to sterilize endoscopes, it is effective in that the consumption of water is decreased, the exchange of water is not required, and a water feed/discharge piping to the sterilizing apparatus is eliminated. According to another aspect of the present invention, there is provided a sterilizing method for medical instruments according to claim 13. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a schematic view showing an example of the constitution of a sterilizing apparatus for medical instruments, useful for understanding, but not embodying the present invention. Fig. 2 is a schematic view showing an example of the constitution of a sterilizing apparatus for medical instruments useful for understanding, but not embodying the present invention; Fig. 3 is a sectional view of a modified sterilization bath in the sterilizing apparatus shown in Figs. 1 and 2, which illustrates a part of the present invention. Fig. 4 is a sectional view showing the constitution of a filter part shown in Fig. 2; Fig. 5 is a sectional view of a connection end part connected to the sterilization bath in Fig. 2 or 3 and a nozzle; Fig. 6 is a schematic view showing an example of the constitution of a sterilizing apparatus for medical instruments in a further different embodiment of the present invention, which is particularly fit for the sterilization of endoscopes; Fig. 7 is a plan view of the sterilization bath shown in Fig. 6 and explaining the position where the connection end parts are formed; Fig. 8 is a perspective view indicating the outward appearance of the sterilizing apparatus of Fig. 6; and Fig. 9 is a perspective view of a state when an endoscope is sterilized by the sterilizing apparatus of Fig. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. A sterilizing apparatus for medical instruments in one mode of the present invention will be described below with reference to the drawings. A sterilizing method for medical instruments in one mode of the present invention is executed by this sterilizing apparatus. It is to be noted here that a filter 60 in the following description is one embodiment of a removing member 60 as specified in the claims, and a nozzle 502 in the following description is one embodiment of a gas feeder 502 as specified in the claims. Fig. 1 shows the basic structure of a sterilizing apparatus 1 for medical instruments. Roughly speaking, the sterilizing apparatus 1 has an electrolyzation device 2, a sterilization bath 3 and a circulation device 4. The electrolyzation device 2 has an electrolytic cell 21 storing electrolytic water 20, a plus electrode 22a and a minus electrode 22b (generally referred to as an electrode 22) soaked in the electrolytic water 20 to produce acidic electrolytic water 20a and alkalic electrolytic water 20b through the electrolyzation of the electrolytic water 20, a power source 23 for supplying direct current to the electrode 22, an ion exchange film 24 set in the electrolytic cell 21 to form a wall as a boundary between the acidic electrolytic water 20a and the alkalic electrolytic water 20b. The amount of the electrolytic water 20 stored in the electrolytic cell 21 is approximately 10ℓ so that the acidic electrolytic water can be generated in a short time. For facilitating the electrolyzation, the electrolytic water 20 is a 0.05% aqueous solution of sodium chloride obtained by dissolving sodium chloride of 5g in city water of 10ℓ. The electrolytic cell 21 is partitioned by the ion exchange film 24 to keep the capacity ratio of an acidic electrolytic water cell 21a and an alkalic electrolytic water cell 21b to be 6:4. The reason why the capacity of the cell 21a is set larger than that of the cell 21b is to use the acidic electrolytic water 20a to sterilize medical instruments in the sterilizing apparatus 1. The electrode 22 is obtained by plating a titanium plate with platinum. As indicated in the drawing, the plus electrode 22a is spaced approximately 95mm from the minus electrode 22b via the ion exchange film 24 to be opposed generally in parallel to each other. The power source 23 feeds a starting current for the electrolyzation of not larger than 5A to the electrode 22 until the electrolytic water 20 reaches a target specific value to be described later and feeds a keep current of about 1A after the target specific value is achieved to maintain the specific value. The starting current is set to be not larger than 5A as above in order to prevent the electrolytic water 20 from being suddenly electrolyzed thereby to restrict the generation of free chlorine as much as possible. The concentration of the generated residual chlorine is about 6ppm. The ion exchange film 24 is a cation exchange film of a fluorocarbon resin. The sterilization bath 3 is for example U-shaped in cross section as shown in Fig. 1 and formed of a resin material such as vinyl chloride or the like. Within the sterilization bath 3 is disposed, for instance, a wire screen 31 on which medical instruments such as syringes, needles, endoscope main bodies, endoscope accessories, etc. are placed. In the present invention, the sterilization bath 3 is formed differently, for example, as indicated in Fig. 3. The same components as in Fig. 1 are designated by the same reference numerals in Fig. 3 and the description therefor will be omitted. The sterilization bath 300 has a first sterilization part 301 and a second sterilization part 302. The acidic electrolytic water 20a is supplied to the first sterilization part 301 to sterilize endoscopes, while medical instruments are sterilized in the second sterilization part 302 by the acidic electrolytic water 20a overflowing from the first sterilization part 301. The overflow method is employed so as to completely sink the endoscopes in the acidic electrolytic water. A basket 303 of metal meshwork is set in the second sterilization part 302 to accommodate medical instruments therein. The circulation device 4 is provided with a feed piping 40 preferably formed of silicon rubber, a pump 41 for feeding the acidic electrolytic water 20a in the electrolytic cell 21 into the sterilization bath 3 through the feed piping 40 and, a return piping 42 preferably formed of silicon rubber to return the acidic electrolytic water 20a supplied to the sterilization bath 3 to the electrolytic cell 21. The above feed piping 40 has one end opened at a bottom part 25 of the acidic electrolytic water cell 21a of the electrolytic cell 21 and the other end opened to the sterilization bath 3. The return piping 42 has a return piping 42a for guiding the acidic electrolytic water 20a in the sterilization bath 3 to the acidic electrolytic water cell 21a of the electrolytic cell 21 and a return piping 42b for guiding the acidic electrolytic water 20a to the alkalic electrolytic water cell 21b via a valve 43. As will be described later, the valve 43 is opened when the 0.05% sodium chloride solution is injected to the sterilization bath 3 when the sterilizing apparatus is started, whereby 60% of the 0.05% sodium chloride solution is fed to the acidic electrolytic water cell 21a, with the remaining 40% fed to the alkalic electrolytic water cell 21b. After the sterilization operation is started, the valve 43 is brought into a closed state to refrain the acidic electrolytic water 20a in the sterilization bath 3 from returning to the alkalic electrolytic water cell 21b. The acidic electrolytic water 20a in the sterilization bath 3 drops because of the gravity to the acidic electrolytic water cell 21a through the return piping 42a. Fig. 2 shows a sterilizing apparatus 5 for medical instruments which is useful for aiding the understanding of the present invention. The same parts as those of Fig. 1 are designated by the same reference numerals in Fig 2, the description of which will be omitted. The above-described sterilizing apparatus 1 is so constituted as to supply the acidic electrolytic water 20a into the sterilization bath 3 only from an upper part 32 of the sterilization bath 3 as shown in Fig. 1. On the other hand, in the sterilizing apparatus 5, in order to increase a sterilization efficiency for the medical instruments set in the sterilization bath 3, a second system comprising a feed piping 52 and a pump 53 which is a system to supply the acidic electrolytic water 20a into the sterilization bath 3 from a bottom part 33 of the sterilization bath 3 is provided, in addition to a first system of a feed piping 50 and a pump 51 which is the same system as that of the sterilizing apparatus 1. Moreover, another set of a piping and a pump is arranged for each of the first and second systems. That is, four feed pipings 50, 52, 54, 56 of two systems are installed in the circulation device 4 of the sterilizing apparatus 5. A connection end part 500 where each feed piping 52, 56 feeding the acidic electrolytic water 20a into the sterilization bath 3 at the bottom part 33 of the sterilization bath 3 is connected and opened to the bottom part 33 may be formed inside the sterilization bath 3 and so oriented as to generate a flow of the acidic electrolytic water 20a in the sterilization bath 3. The flow of the acidic electrolytic water brought about in the sterilization bath 3 improves the sterilization efficiency for medical instruments set in the sterilization bath 3. In order to generate the above flow of the acidic electrolytic water, the connection end part 500 is arranged at the bottom part 33 of the sterilization bath 3 in a manner to jet the acidic electrolytic water 20a out, for instance, in parallel to a bottom face 34 of the sterilization bath 3. It is more favorable if the connection end part 500 is arranged to be nearly completely accommodated in a recessed part 35 formed at the bottom face 34 of the sterilization bath 3 and make an acute angle between the direction in which the acidic electrolytic water 20a is jetted and the bottom face 34, as indicated in Fig. 5. The recessed part 35 is formed to less project the connection end part 500 from the bottom face 34 thereby to refrain the connection end part 500 from being an obstacle to the medical instruments set in the sterilization bath 3. It is desirable if a nozzle 502 is set at a part 501 where the feed piping 52, 56 is connected to the sterilization bath 3 to suck the air into the feed piping 52, 56 by the flow of the acidic electrolytic water 20a in the feed piping 52, 56, as shown in Fig. 5. While the nozzle 502 feeds the air to the interior of the feed piping 52, 56 as mentioned above, an opening part at one end of the nozzle 502 is positioned higher than the water level in the sterilization bath 3 so as to prevent the acidic electrolytic water 20a from leaking outside the piping via the nozzle 502. Alternatively, the nozzle 502 may be connected to an air pump 504 thereby to forcibly feed the air into the piping 52, 56. The set position for the nozzle 502 is desirably the above part 501, but not limited to this position and may be an adequate position between the pump 53, 57 and the sterilization bath 3. Or, the nozzle 502 may be arranged at a suitable position between the pump 51, 55 of the feed piping 50, 54 and the sterilization bath 3. A filter 60 to remove solid substance included in the acidic electrolytic water 20a discharged from the sterilization bath 3 is disposed in the circulation device 4 in the sterilizing apparatus 5, more specifically, at the return piping 42a which returns the acidic electrolytic water 20a in the sterilization bath 3 to the acidic electrolytic water cell 21a of the electrolytic cell 21. A case 65 accommodating the filter 60 is placed on a top plate 26 of the electrolytic cell 21. The acidic electrolytic water 20a passing the filter 60 falls into the acidic electrolytic water cell 21a. The filter 60 will be depicted with reference to Fig. 4. The filter 60 is made of polypropylene in a cylindrical form as illustrated to trap solid substance of a size of not smaller than several tens µm or so. The filter 60 is fitted inside the case 65. The return piping 42a is connected at a predetermined position of an upper plate 65a of the case 65 to feed the acidic electrolytic water 20a from the sterilization bath 3 to the side of the inner periphery of the cylindrical filter 60. A net-like coarse filter 67 of polypropylene is set at a bottom part 66 of the case 65 so as to filter the acidic electrolytic water 20a dropping to the acidic electrolytic water cell 21a directly through a cylinder or trunk part of the filter 60 without passing through the filter 60. Further, an opening 68 is formed to drop the acidic electrolytic water 20a passing the filter 60 to the acidic electrolytic water cell 21a. The case 65 is so designed as to allow the filter 60 to be easily set/detached to the case 65. Fig. 6 indicates a sterilizing apparatus 7 for medical instruments in a further different embodiment of the present invention. Among the parts shown in Fig. 6, the same as in Fig. 2 are represented by the same reference numerals and the description therefor will be omitted here. The sterilizing apparatus 7 is particularly targeted to endoscopes as medical instruments to be sterilized. Moreover, the sterilizing apparatus 7 is, with the aim of preventing the infection among patients and sterilizing the endoscopes in a short time, to sterilize only a part of the endoscopes having germs, etc. adhered thereto as a result of the inspection to patients. Therefore, although a manipulation part 713 of the endoscope and the periphery thereof are generally not sterilized, it is possible to sterilize the manipulation part 713 as well in a sterilization bath of the apparatus to be described later. In the sterilizing apparatus 7, the circulation device 4 includes feed pipings 70, 72, 74, 76 and pumps 71, 73, 75, 77. The feed pipings 70, 72 and pumps 71, 73 feed the acidic electrolytic water 20a to a sterilization bath 310 from two points at a bottom part 314 of the sterilization bath 310. The feed piping 74 and pump 75 feed the acidic electrolytic water 20a mainly through a forceps opening 713a and a suction button opening 713b of the manipulation part 713 of an endoscope 710 into an internal insertion part 711 to be inserted into the body of a patient. Meanwhile, the feed piping 76 and pump 77 feed the acidic electrolytic water 20a mainly through an air/water feed button opening 713c of the manipulation part 713 into a connection part 712 to be connected to a light source device for the endoscope (not shown). The sterilization bath 310 of the sterilizing apparatus 7 includes an annular sterilization bath 311 where the internal insertion part 711 of the endoscope 710 is stored and an accessory sterilization bath 312 integrally formed with the sterilization bath 311 which is located at a central part of the sterilization bath 311 and to which the acidic electrolytic water 20a overflowing from the sterilization bath 311 runs in. The insertion part 711 wound along the outline of the sterilization bath 311 is accommodated in the sterilization bath 311. Accessories of the endoscope 710 and other medical instruments are kept in a metal netting 313 in the sterilization bath 312. The sterilization bath 312 holds one end of the connection part 712. In the sterilizing apparatus 7 of the above-described constitution, the outer face of the insertion part 711 of the endoscope 710 is sterilized by the acidic electrolytic water 20a filled in the sterilization bath 311, and moreover, the interior of each of the manipulation part 713 including the forceps opening 713a, insertion part 711 and connection part 712 is sterilized by the acidic electrolytic water 20a fed to the endoscope 710 through the feed pipings 74, 76. The acidic electrolytic water 20a supplied into the insertion part 711 is discharged out from a front end 711a of the insertion part 711 to the sterilization bath 311. On the other hand, the acidic electrolytic water 20a supplied into the connection part 712 is discharged from a connection end part 712a of the connection part 712 to the accessory sterilization bath 312. The sterilizing apparatus 7 alike has the recessed part 35 as described in the preceding embodiments at the bottom part 314 of the sterilization bath 310. The connection end part 500 is formed to be nearly totally accommodated in the recessed part 35. Also the nozzle 502 is provided. The connection end part 500 is oriented to jet the acidic electrolytic water 20a in a direction indicated by an arrow 505 in Fig. 7 so as to form a flow of the water in one direction along the outline of the sterilization bath 311. Moreover, the connection end parts 500 are separated 180° on the circumference of the sterilization bath 311 as in Fig. 7. In the meantime, the insertion part 711 is wound in an opposite direction to the direction of the water flow and accommodated in the sterilization bath 311. The outward appearance of the sterilizing apparatus 7 is as shown in Fig. 8. In Fig. 8, the same parts as in Fig. 6 are indicated by the same reference numerals. At the same time, in Fig. 8, a decorative plate at the front face of the apparatus is removed to show the electrolytic cell 21, etc. inside the apparatus. Moreover, the electrolytic cell 21 is displayed in partly broken in order to show the plus electrode 22a, minus electrode 22b and ion exchange film 24. A reference numeral 750 is a discharge pipe. When the discharge pipe 750 is inclined to the front face of the sterilizing apparatus 7 about a lower part of the electrolytic cell 21, the acidic electrolytic water 20a and alkalic electrolytic water 20b in the electrolytic cell 21 are mixed, neutralized and discharged outside the apparatus. Fig. 9 shows an arrangement how the sterilizing apparatus 7 and the endoscope 710 are set to sterilize the endoscope by the sterilizing apparatus 7. In other words, Fig. 9 shows a state that after the insertion part 711 is wound and accommodated in the sterilization bath 311 as discussed above, then a lid 751 is closed, the manipulation part 713 is held by a supporting tool 770 supported at the rear face of the sterilizing apparatus 7 and the connection part 712 is held by the sterilization bath 312. In each of the foregoing embodiments, the acidic electrolytic water 20a is adapted to freely drop from the sterilization bath 3 to the electrolyzation device 2 in order to make the sterilizing apparatus compact, cost-saving, and diminish failures, etc. through the reduction of the number of pumps. In other words, the sterilization bath 3 is located above the electrolytic cell 21. However, the positional relationship of the sterilization bath 3 and electrolytic cell 21 is not limited to this. For example, the sterilization bath 3 and the electrolyzation device 2 can be freely arranged if the acidic electrolytic water 20a is forcibly supplied from the sterilization bath 3 to the electrolytic cell 21. The operation of the sterilizing apparatuses for medical instruments constructed as above will be depicted below. The operation of the sterilizing apparatus 7 of Fig. 8 will be discussed herein by way of example. Approximately 10ℓ city water is poured into a bucket or the like container, to which a prescribed amount of sodium chloride is added as described before, whereby the electrolytic water 20 of 0.05% sodium chloride aqueous solution is produced. The electrolytic water 20 is injected to the accessory sterilization bath 312. The injected electrolytic water 20 is, through the return pipings 42a, 42b, distributed and injected to the acidic electrolytic water cell 21a and the alkalic electrolytic water cell 21b. As mentioned earlier, since the flow rate of the return pipings 42a and 42b is set to be 6:4, 6ℓ among the 10ℓ electrolytic water 20 is injected to the acidic electrolytic water cell 21a and 4ℓ is injected to the alkalic electrolytic water cell 21b. Then, a power switch of the sterilizing apparatus 7 is manipulated and a timer is set to start to electrolyze the electrolytic water 20 one hour earlier than the time to start the sterilization. At the above-set time, the starting current of not larger than 5A is provided from the power source 23 to the plus and minus electrodes 22a, 22b, so that the electrolytic water 20 is started to be electrolyzed in the electrolytic cell 21. The sterilizing apparatus 7 is equipped with a weekly timer which can be set to start the electrolyzation at a constant time on week days. The electrolyzation produces the acidic electrolytic water 20a in the acidic electrolytic water cell 21a which has the plus electrode 22a, and the alkalic electrolytic water 20b in the alkalic electrolytic water cell 21b with the minus electrode 22b. The electrolyzation is carried out for one hour so as to obtain the acidic electrolytic water 20a fit for the sterilization. During the time, a lamp indicating that the electrolytic water is being prepared is turned on. It is generally said that microbes such as germs and the like are not alive in the environment of a PH of 2.7 or lower and an oxidation-reduction potential (ORP based on an Ag/AgCℓ electrode) of 1000mV or higher, and therefore the acidic electrolytic water 20a suitable for the sterilization should have the PH of not higher than 2.7 and the oxidation-reduction potential of not lower than 1000mV. After the lapse of one hour, the sterilizing apparatus is ready for sterilization, and a lamp indicative of the completion of the preparation is turned on. The acidity and the oxidation-reduction potential of the acidic electrolytic water 20a deteriorate with time if the acidic electrolytic water 20a are left naturally, and are also deteriorated by the sterilization operation of medical instruments to be described later. As such, in order to maintain the acidic electrolytic water 20a at a specific value fit for the sterilization at all times, the keep current of about 1A is fed to the plus and minus electrodes 22a and 22b in place of the starting current when the preparation is completed. It is confirmed with the use of a test paper that the acidic electrolytic water 20a holds the PH value and oxidation-reduction potential value in the above-mentioned predetermined range. The preparation for starting the sterilization is completed in the above-described procedures. Now, the operation to sterilize the endoscope 710 will be depicted below. As described with reference to Figs. 6 and 9, the endoscope 710 is set to the sterilizing apparatus 7. When a "sterilization switch" of the sterilizing apparatus 7 is manipulated, pumps 71, 73 are activated and the acidic electrolytic water 20a is supplied from the acidic electrolytic water cell 21a to the insertion part sterilization bath 311 of the sterilization bath 310. At the same time, pumps 75, 77 are driven to feed the acidic electrolytic water 20a from the acidic electrolytic water cell 21a into the manipulation part 713, insertion part 711 and connection part 712 of the endoscope 710. Accordingly, the interior of the manipulation part 713, insertion part 711 and connection part 712 is sterilized. Because of the nozzle 502 set at the feed pipings 70, 72 as described before, the acidic electrolytic water 20a is mixed with the gas and the mixture is sent to the sterilization bath 311. In the sterilization bath 311, the connection end part 500 generates the flow of the water in the opposite direction to the winding direction of the insertion part 711 as described above, so that the outer surface of the insertion part 711 can be sterilized effectively. The acidic electrolytic water 20a overflowing from the sterilization bath 311 runs into the sterilization bath 312 and sterilizes the accessories. The acidic electrolytic water 20a flowing in the sterilization bath 312 is returned to the acidic electrolytic water cell 21a through the return piping 42a because the valve 43 is closed. When the acidic electrolytic water 20a returning to the acidic electrolytic water cell 21a passes through the filter 60 and coarse filter 67, solid substances, etc. removed from the endoscope 710 in the sterilization operation are filtered. The PH and oxidation-reduction potential of the acidic electrolytic water 20a returned to the electrolytic cell 21 are adjusted to be the above-described values by the action of the keep current. The acidic electrolytic water 20a is again sent into the sterilization bath 311, manipulation part 713, insertion part 711 and connection part 712 by the pumps 71, 73, 75, 77. In the above manner, the acidic electrolytic water 20a of the constant PH and constant oxidation-reduction potential is circulated between the electrolytic cell 21 and sterilization bath 310 and between the sterilization bath 310 and interior of the endoscope, thereby sterilizing the endoscope 710. The sterilization in the sterilizing apparatus 7 takes 7 minutes per endoscope. One endoscope 710 is completely sterilized in the above operation and taken out from the sterilizing apparatus 7. Since the acidic electrolytic water 20a is returned to neutral water when left as it is, the acidic electrolytic water 20a remaining on the outer surface of the endoscope 710 and inside the manipulation part 713, insertion part 711 and connection part 712 is returned to the original neutral electrolytic water. Therefore, the conventional work to rinse the disinfectant is eliminated, and thus the sterilizing apparatus enables the sterilization of endoscopes in a short time. According to the embodiments, while the acidic electrolytic water 20a is circulated, the PH and oxidation-reduction potential of the water 20a are adjusted and maintained at constant values, and more desirably, solid substances are removed. Owing to this, approximately 20 endoscopes corresponding to the number of inspections carried out in one day can be repeatedly sterilized without exchanging the acidic electrolytic water 20a. After all inspections carried out in one day are finished, the discharge pipe 750 of the sterilizing apparatus 7 is inclined forward of the apparatus as shown in Fig. 8 to discharge the electrolytic water 20 in the electrolytic cell 21, for example, to a bucket or the like container. Since the acidic electrolytic water 20a and the alkalic electrolytic water 20b in the electrolytic cell 21 are mixed when discharged from the discharge pipe 750, the electrolytic water 20 discharged to the container becomes neutralized water and therefore does not make trouble to the environment even when let out to the drainage. The alkaline electrolytic water 20b is stored in the electrolytic cell 21 so as to bring about the above neutralization at the discharging time. The acidic electrolytic water 20a maintained at the predetermined PH and oxidation-reduction potential values is circulated between the electrolytic cell 21 and sterilization bath 310 thereby to sterilize medical instruments. The time to start the next sterilization after one sterilization is finished is thus shortened. Regarding the sterilization of endoscopes, only parts of the endoscope in touch with the interior of the patients or humor are sterilized according to the embodiments, and therefore the endoscope can be easily set/removed to the sterilization bath 3. Furthermore, to sterilize the endoscopes by circulating the acidic electrolytic water 20a is effective in reducing the consumption of the acidic electrolytic water, and to eliminate the necessity for exchanging the acidic electrolytic water, and to eliminate a water feed/discharge piping to the sterilizing apparatus. In addition, since the electrolytic water is supplied/discharged by means of the bucket or the like container in the embodiments, no positional limit is imposed to set the sterilizing apparatus. As is fully described hereinabove, according to the present invention, the acidic electrolytic water for sterilizing medical instruments stored in the sterilization bath is produced at the electrolytic cell, supplied to the sterilization bath and returned to the electrolytic cell from the sterilization bath. That is, the acidic electrolytic water is circulated between the electrolytic cell and the sterilization bath to sterilize the medical instruments. Accordingly, the time to start the next sterilization after the completion of one sterilization operation is shortened. Moreover, the acidic electrolytic water is used as the sterilization liquid and the acidic electrolytic water remaining on the surface of medical instruments after the sterilization is neutralized with time. The sterilization liquid is accordingly not necessary to rinse after the sterilization, contrary to the conventional art, thereby achieving the sterilization of medical instruments in a short time. The sterilization is easily conducted simply by putting the medical instruments into the sterilization bath. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that the scope of the present invention is defined by the appended claims.

Claims: A sterilizing apparatus (7,300) for medical instruments comprising: an electrolyzation device (2) which has an electrolytic cell (21) capable of producing, in an acidic electrolytic water cell (21a), acidic electrolytic water (20a) as a disinfectant by electrolyzing electrolytic water when present in the electrolytic cell; a first sterilization bath (301, 311) capable of storing first medical instruments to be sterilized; the apparatus having means (40, 70, 71) serving to transfer said acidic electrolytic water (20a) from said acidic electrolytic water cell (21a) to said first sterilization bath (301, 311); characterised in that : a second sterilization bath (302, 312) capable of storing further medical instruments to be sterilized is provided; whereby the first sterilization bath (301, 311) and the second sterilization bath (302, 312) are so constructed that when the first sterilization bath is filled with acidic electrolytic water said acidic electrolytic water can overflow from said first sterilization bath (301, 311) into said second sterilization bath (302, 312); and means (42a) for guiding the acidic electrolytic water (20a) from said second sterilization bath (302, 312) back into the acidic electrolytic water cell (21a) of the electrolyzation device (2). A sterilizing apparatus as defined in Claim 1 wherein the first sterilization bath (301, 311) is of annular form to facilitate the placing of an internal insertion part (711) of an endoscope (710) therein; and the second sterilization bath (302, 312) is integrally formed with the first sterilization bath (301, 311) and located at a central part of the annular first sterilization bath. A sterilizing apparatus as defined in Claim 2 and wherein a metal netting (313) is accommodated in the second sterilization bath (302, 312) for the placing therein of accessories of an endoscope (710) as well as other medical instruments. A sterilizing apparatus as defined in any of Claims 1 to 3 and comprising a power source (23) for feeding a starting current of not larger than 5A for the electrolyzation to the electrolytic water until the electrolytic water reaches a target specific value. A sterilizing apparatus for medical instruments according to Claim 4, wherein the electrolyzation device includes means for feeding a keep current of a smaller value than the starting current for electrolyzation in order to maintain the target specific value after the electrolytic water has reached the target specific value, to the electrolytic cell in place of the electrolyzation starting current. A sterilizing apparatus for medical instruments according to any one of Claims 1 to 5, wherein the circulation device is provided with a feed piping (70) connecting the electrolytic cell with the first sterilization bath (310, 311), a return piping (42a) for returning the acidic electrolytic water from the second sterilization bath (302, 312) to the electrolytic cell (21a), and a pump (71) set at the feed piping (70) for feeding the acidic electrolytic water from the acidic electrolytic water cell (21a) to the first sterilization bath (301, 310). A sterilizing apparatus for medical instruments according to Claim 6, wherein the return piping is provided with a removing member (60) for removing solid substance included in the acidic electrolytic water returning from the second sterilization bath (302, 312) to the acidic electrolytic water cell (21a). A sterilizing apparatus for medical instruments according to Claims 6 or 7, wherein a connection end part (500) where the feed piping is connected with the first sterilization bath generates a flow of the acidic electrolytic water in the first sterilization bath. A sterilizing apparatus for medical instruments according to any one of Claims 6 to 8, wherein the feed piping (52, 56) has a gas feeder (502) to allow a gas to be included in the acidic electrolytic water supplied to the first sterilization bath. A sterilizing apparatus for medical instruments according to any one of Claims 1 to 9, wherein the electrolyzation device (2) has an ion exchange film (24) for the production of the acidic electrolytic water fitted in the electrolytic cell (21). A sterilizing apparatus for medical instruments according to any one of Claims 1 to 10, wherein the electrolytic water is a 0.05% aqueous solution of sodium chloride. A sterilizing apparatus for medical instruments according to any one of Claims 6 to 11, wherein, when one of the medical instruments is an endoscope, the feed piping is provided with a first feed piping (70, 72) for feeding the acidic electrolytic water (20a) to the first sterilization bath (311) and a second feed piping (74, 76) which has detachable means for coupling to the endoscope and is capable when coupled to the endoscope of feeding the acidic electrolytic water into the endoscope. A sterilizing method for medical instruments comprising: providing a sterilizing apparatus according to any of claims 1-12 and then carrying out: a producing step whereby acidic electrolytic water is produced as a disinfectant by electrolyzing electrolytic water stored in the electrolytic cell; a setting step whereby medical instruments to be sterilized are set in the first and second sterilization baths; and a circulation/sterilizing step whereby the acidic electrolytic water is circulated between the acidic electrolytic water cell (21a) and the first sterilization bath (301,311) thereby sterilizing medical instruments placed in said first sterilization bath; permitting acidic electrolytic water in said first sterilization bath to overflow into said second sterilization bath (302, 312); and permitting acidic electrolytic water to flow from said second sterilization bath back into said acidic electrolytic water cell (21a) of the electrolyzation device (2). A sterilizing method for medical instruments according to Claim 13 wherein the acidic electrolytic water produced in the electrolytic cell by the electrolyzation device has a PH of not larger than 2.7 and an oxidation-reduction potential of not smaller than 1000mV. A sterilizing method according to claim 13, whereby the sterilizing apparatus provided comprises a power source according to claim 4 which feeds a starting current in said producing step for the electrolyzation to the electrolytic water of not larger than 5A to prevent the electrolytic water from being suddenly electrolyzed and so to restrict the generation of free chlorine until the electrolytic water reaches a target specific value. A sterilization method according to Claim 13 or Claim 15 wherein the medical instruments are endoscopes and accessories of the endoscopes.

Inventors: HAYASHI KOUZABURO, MAEDA TOYOYUKI, TERAKURA SEIJI, HAYASHI, KOUZABURO, MAEDA, TOYOYUKI, TERAKURA, SEIJI
Applicants: KAIGEN CO LTD, KAIGEN CO., LTD.
Application year: 1996
Main classification: A61L2
IPC codes: C02F1, A61L2