CA1273774A

CA1273774A - Automated liquid sterilization system

Info

Publication number: CA1273774A
Application number: CA000528775A
Authority: CA
Inventors: Raymond C. Kralovic; Edward T. Schneider
Original assignee: Steris Corp
Current assignee: Steris Corp
Priority date: 1986-02-06
Filing date: 1987-02-02
Publication date: 1990-09-11
Anticipated expiration: 2007-09-11
Also published as: JPS62186860A; JPH0430865B2; ATE63222T1; ES2021702B3; GR3001926T3; DE3769806D1; EP0232170B1; US4731222A; EP0232170A2; EP0232170A3; US4892706A

Abstract

AUTOMATED LIQUID STERILIZATION SYSTEM

Abstract of the Disclosure Each of a plurality of modules (A) have fittings (14) with automatically closed check valves (16) therein such that the interior of the module is hermetically sealed. The module is selectively interconnected with a sterilizer apparatus (B). Interconnecting tubing (60) selectively supplies liquid from a reservoir (30) to the module. A sterilant injection chamber (56) receives and punctures a sterilant ampule such that incoming water mixes with the sterilant concentrate forming a sterilant solution which is carried to the reservoir. A reservoir outlet valve (70) selectively permits the sterilant solution to pass from the reservoir through the interconnecting tubing into the module until the module and interconnecting tubing are completely filled.
Thereafter, the reservoir outlet valve closes holding the sterilant in the interconnecting tubing as well as the module for sufficient duration to sterilize both.
Concurrently, additional tap water is heated in the reservoir until it is sterile. Thereafter, the reservoir outlet valve is opened again and the sterilant solution is drained and rinsed from the module with the sterile water. An air pump (86), a heater (84), and a submicron sterilization filter (82) supply heated, sterile drying air through the reservoir, connecting tubing, and module to dry the sterilized device.

Description

1273 7'74 AUTOMATED LIOUID STERILIZATION SYSTEM

Background of the_Invention The present invention pertains to the sterilization art. The present invention finds particular application in conjunction with the sterilization of medical devices and will be described with particular reference thereto.
It is to be appreciated, however, that the invention may also find application in the sterilization, disinfecting, and liquid immersion treatment of other devices.
Sterilization is defined as the absence of all life forms including bacterial endospores which are the living organisms most resistant to known sterilants.
Disinfection, by distinction, only connotes the absence of pathogenic life forms. The term "microbial decontamination" is used herein as the term generic to both sterilization and disinfecting.
A sterilizer or sterilizing apparatus must demonstrate sporicidal activity which meets the standards specified in the United States Pharmacopeoia (20th revision; U.S. Pharmacopeoia Convention Inc.;
Rockville, MD) or the standards of the Association of Official Analytical Chemists (Official Methods of Analysis; 13th edition; Washington, D.C.). It is to be appreciated that establishing the absence of all life forms in sterilization is more readily documented and controlled than the elimination of pathogenic but not all life forms in disinfection.

~2'73~74

-2--Some high level disinfectants, such as glutaraldehyde and stabilized hydrogen peroxide~ are also sporicidal. However, the six to eight hours required for 2~ glutaraldehyde to achieve sterilization renders it impractical as a sterilant. Disinfection is, of course, achieved in a considerably shorter exposure time. ~ommercially, substantially all high level disinfectants are utilized in liquid form. Liquid sterilization and disinfecting processes immerse the 1~ item to be sterilized in a bath or vat of the sterilizing or disinfecting liquid.
Because bacterial spores are the life form which is most resistant to sterilants, they are commonly used as reproducible, stable indicators of the ef~ectiveness of 15 a sterilization process, In the medical industry, a sterility assurance level (SAL) of less than or equal tO
one chance in one million of having a contaminated item is generally regarded as the minimum acceptable level for medical devices which are designed to be used in 20 sterile tissues of the human body. In practice, this level of assurance is obtained by establishing the exposure time required to sterilize a given quantity of bacterial endospores known to be resistant to the sterilant. Bacillus stearothermophilus is a suitable indicator for steam or moist heat sterilization and spores of bacillus subtilus are suitable indicators for dry heat or ethylene oxide sterilization. The rate of destruction of the spores at the sterilization conditions is expressed as the time required to reduce the viable spore population by 90% or 1 log. This destruction rate is commonly referenced as the D value.
From the D value, which is a rate function, the time required for a given sterility assurance level can be calculated. For example, spores of bacillus ~1273~7~

stearothermophilus typically have a D value in saturated steam oF 250~F and 15 psig of two minutes. Thus, an item with 100 spores (10 ~) will have the spore count reduced to one spore (10 ) in four minutes, i.e. a 2 log reduction. Because sterility requires an assurance level of one in a million (10 6), an additional exposure time of 12 minutes (6x2 minutes) or a total exposure time of 16 minutes is required for c~mplete sterilization.
Pathogenic microorganisms, which are mostly vegetative forms of bacteria, do not have the stability to enable a D value or the equivalent to be derived after storage. There is no accompanying biological indicator applicable to pathogenic organisms which 15 functions as a reliable, reproducible, and stable indicator of the effectiveness of the disinfection process. Accordingly, assuring that disinfection has occurred is more difficult and unreliable than assuring sterilization.
This inability to assure the effectiveness of disinfectants with biological indicators is compounded by the lack of easily measured physical parameters which demonstrate in minimal necessary conditions for disinfection. For liquid disinfectants, the active 25 agent must be measured in individual discrete samples by a wet chemical method. Such methods are not easily automated nor do they provide continuous real time monitoring. Accordingly, liquid disinfectants are generally considered unsuitable for use by unskilled 30 personnel.
Another problem compounding use of liquid disinfectants is that the active agent is commonly toxic to human tissue and must be removed by rinsing with water. Frequently, tap water is used as the rinse.

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However, the same microorganisms that are killed by the disinfectant are found in tap water and can be redeposited therefrom. Thus, the tap water rinse may deEeat the disinfection process. Because sterile rinse water or saline are relatively expensive, there is a tendency for medical facilities to use a minimal amount of sterile rinse which frequently leaves a disinfectant chemical residue.
Yet another drawback to liquid disinfection 10 processes is that the disinfected state cannot be maintained. No effective packaging or containment systems are available which can guaran~ee the preservation of the disinfected state of an item until use. Thus, with disinfection, a patient is apt to be 15 exposed to both chemical residue and biological risks.
Despite the short comings of liquid disinfectants, vast quantities are used for disinfecting medical devices. Many of these medical devices are made of plastic or have complex lens systems, e.g. rigid or 20 flexible endoscopes. The plastic elements and lens system may be destroyed or have their useful lives severely curtailed by thermal sterilization systems such as steam. Conventional ethylene oxide sterilization (which is thermally less severe than steam) requires a 25 relatively long exposure time, on the order of three and a halE hours. Ethylene oxide, which is relatively expensive compared to liquid sterilants, requires an even longer aeration time, on the order of 8-12 hours.
The pressure excursions of the ethylene oxide 30 sterilizaton equipment may damage lens instruments.
Because ethylene oxide is a toxic, volatile gas, operator safety is a serious concern.
Accordingly, liquid sterilants rather than gaseous sterilants are commonly used for disinfection of heat 1;~7377~

sensitive and expensive medical devices in medical facilities. Liquid sterilants are rapid when used to achieve disinfection, cost effective, and do minimal damage to medical devices. However, the prior art liquid sterilant/disinfection methods and apparatus are lacking in assurance and reproducibility of disinfection, removal of chemical residues, safety, cost, and the ability to preserve the disinfected or sterile state until reuse. In addition, normal methods for use of liquid sterilants can produce only a disinfected state because methods to produce and preserve the sterile state have not been available.
In accordance with the present invention, a new and improved liquid sterilization method and apparatus are provided which overcomes the above referenced problems and others.

Summary of the Invention In accordance with one aspect of the present invention, a method of microbial decontamination is provided. Both a chamber containing at least one item to be microbially decontaminated and the tubing which interconnects the chamber with a rinse solution source are filled with an anti-microbial liquid solution. The anti-microbial solution is held in the chamber and the interconnecting tubing for a preselected duration which is sufficiently long to microbially decontaminate the interior of the chamber, the item, and the interconnecting tubing. Thereafter, the anti-microbial solution is rinsed from the interconnecting tubing, the chamber interior, and the item with the microbially uncontaminated rinse solution from the rinse solution source.
In accordance with another aspect of the present invention, a method of sterilizing or disinfecting is provided. The item to be sterilized or disinfected is ~273~7~

enclosed in a module which is closed to contamination from the ambient atmosphere. A preselected dose of an anti-microbial concentrate is discharged into a dilution fluid to form the anti-microbial solution. The module is filled with the solution and held until the item is disinfected or sterilized. Thereafter, the solution is discarded assuring that the solution is mixed fresh for each item. A
microbially decontaminated or sterile rinse fluid is passed through the module and the item is stored in the module to retain its disinfected or sterile state.
In accordance with another aspect of the present invention, a method of disinfection is provided in which an item to be disinfected is immersed in a disinfectant solution. A current is induced between the item and an electrode in the solution to inhibit galvanic corrosion.
In accordance with another aspect of the present invention, a microbial decontamination apparatus is provided.
The apparatus includes a chamber for containing at least one item to be microbially decontaminated and a source of microbially uncontaminated rinse solution. The interconnecting tubing connects the rinse source and the chamber such that the rinse solution selectively passes from the source to the chamber. A means is provided for holding the anti-microbial solution in contact with the interconnecting tubing and chamber for a preselected duration.
In accordance with another aspect of the present invention, a system for microbially decontaminating items to a disinfected or sterile state and storing the items in such state is provided. The system includes a plurality of modules, each capable of containing at least one item to be microbially decontaminated. The modules have a plurality of fluid ports that provide fluid flow into and out of the module when interconnected with fittings which are isolated from microbial contamination from the atmosphere when the rJ~ .

~273774 module is disconnected from the fittings. One of the fittings is interconnected with a drain and another of the fittings is interconnected with interconnecting tubing for interconnecting the module with a rinse fluid source. An anti-microbial solution means selectively supplies an anti-microbial solution through the interconnecting tubing to the module and a rinse means selectively supplies a microbially uncontaminated rinsing solution from the rinse fluid source to the module.
In accordance with another aspect of the present invention, a disinfection apparatus is provided that includes the container for holding at least one item to be disinfected. At least one electrode is disposed in an electrically conductive relationship with a disinfectant solution received in the container.
Other aspects of this invention are as follows:
A microbial contamination removing apparatus comprising:
a source of liquid rinse fluid;
a means operatively connected with the source for eliminating a microbial contamination from the liquid rinse fluid;
a chamber including a closure means which has opened and closed configurations therefor, wherein in the opened configuration, said chamber is opened to receive an item to be decontaminated in an interior thereof, and in the closed configuration, said chamber isolates the received item from the ambient atmosphere and other sources of microbial contamination;
interconnecting tubing connecting the source and said chamber;
a means for selectively holding liquid anti-microbial solution in both the interconnecting tubing and the chamber for a sufficient duration to 12~3774 7a decontaminate the chamber interior, the item, and the interconnecting tubing from the source to the chamber.
A method of microbial decontamination, the method comprising:
enclosing an item to be microbially decontaminated in a chamber interior which is isolated from microbial contamination from the ambient atmosphere;
causing an anti-microbial solution to flow into the chamber interior and an interconnecting flow path defined between a source of a rinse liquid and the chamber interior and direct fluid communication therewith;
retaining the antimicrobial solution in the chamber interior and the interconnecting flow path until the item, the chamber interior, the flow path, and the interior surfaces are free of microbial contamination, whereby freeing all surfaces between the rinse fluid source and the chamber of microbial contamination assures that the liq~id rinse fluid will not carry microbial contaminants from contaminated surfaces into the chamber;
draining the antimicrobial solution from the chamber interior and the interconnecting flow path;
passing the liquid rinse fluid from the liquid rinse source only in contact with the microbial contamination-free flow path surfaces into the chamber to rinse the item;
draining the liquid rinse fluid from the chamber interior.
A method of removing microbial contamination from medical instruments, the method comprising:
disposing a medical instrument to be freed from microbial contamination in a chamber interior;
closing the chamber interior to penetration by microbial contaminates;

~27377~
7b filling interconnecting tubing from the chamber interior to a rinse solution source and the chamber interior with a liquid antimicrobial agent;
retaining the liquid antimicrobial agent in the chamber interior and the interconnecting tubing for a preselected duration, which preselected duration is sufficiently long to eliminate microbial contamination in the chamber interior, of the medical instrument, and in the interconnecting tubing;
passing a microbial contaminant-free liquid rinse solution from the rinse solution source only through the microbial contamination-free interconnecting tubing into the microbial contamination-free chamber interior to rinse the liquid antimicrobial agent from the interconnecting tubing, the module, and the medical instrument, whereby the liquid rinse solution passes only in contact with microbial contamination-free surfaces to prevent microbial contamination of the liquid rinse solution.
A method of removing microbial contamination from items, the method comprising:
a) enclosing an item to be freed of microbial contamination in an interior of a module which is closed to penetration of microbial contaminants from the 5 ambient atmosphere;
b) removably attaching the module with tubing that connects the module with a source of microbial contaminant-free rinse liquid;
c) causing a liquid antimicrobial solution to flow into and remain in contact with the module interior and the tubing which connects the module with the source of rinse liquid until the item and the module intericr are free of microbial contamination;
d) draining the liquid antimicrobial solution 5 from the module interior;

1 27377~
7c e) passing a microbial contamination-free rinse liquid from the source thereof into the module interior to rinse the item;
f) detaching the module while maintaining the module closed to microbial contaminants;
g) storing the item in the module to retain its microbial contaminant-free condition.
A method of making an item free of microbial contamination, the method comprising:
enclosing the item in a chamber which is isolated from microbial contamination from the ambient atmosphere;
providing interior surfaces which define a liquid rinse flow path between the chamber and a source of microbial contamination-free rinse liquid;
causing an antimicrobial solution to flow into the chamber and into all flow path interior surfaces which define the interconnecting flow path from the liquid rinse source into the chamber and every interior surface in direct fluid communication therewith;
retaining the antimicrobial solution in the chamber and the interior surfaces until the interior surfaces, the item, and the chamber are free of microbial contamination, whereby freeing all surfaces between the rinse fluid source and the chamber of microbial contamination assures that the liquid rinse fluid will not carry microbial contaminants from contaminated surfaces into the chamber;
draining the antimicrobial solution from the chamber and the interconnecting flow path;
passing the liquid rinse fluid from the liquid rinse source only in contact with the microbial contamination-free flow path surfaces into the chamber to rinse the item;
draining the liquid rinse fluid from the chamber.

127377~
7d One advantage of the present invention is that it produces a high sterility assurance level (SAL).
Another advantage of the present invention is that it avoids thermal degradation to the microbially decontaminated devices.
Further advantages reside in increased operator safety, greater cost efficiency, and longer shelf life of microbially decontaminated devices.
Still further advantages will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiment.

Brief Descri~tion of the Drawinqs The invention may take form in various steps and arrangements of steps and in various parts and arrangements of parts. The FIGURES are only for purposes of illustrating a preferred embodiment and are not to be construed as limiting the invention.

1;~73774 FIGURE 1 is a perspective ~iew in partial section of a sterilizing apparatus in accordance with the present invention with the housing and a module illustrated in phantom; and, FIGURE 2 is a diagrammatic illustration of the sterilizing apparatus and module of FIGURE 1.

Detail~d Description of the Preferred Embodiment With reference to FIGURE 1, a module A ~or containing a medical device or other item to be sterilized is selectively interconnectable with a sterilizer apparatus B. Although the illustrated module is adapted to receive an endoscope, other shaped modules 15 will be configured in accordance with the medical devices to be sterilized. During the sterilization process, the sterilization unit B serially supplies a sterilant solution, a sterile rinse solution, and a sterile drying gas to the module. The sterilant is held in the module and the plumbing of the unit through which the sterile rinse flows to the module for a sufficient duration to assure sterilization. During the hold or sterilization period, the unit heat sterilizes tap water or another suitable rinse solution. Optionally, other rinse water sterilization techniques may be used, such as radiation. If desired, wetting, lubricant, anticorrosion agen~s and the like may be mixed with the rinse water. After the sterilization process, the hermetically sealed module and the sterilized item are stored as a unit until the module is opened and the device is removed for use. This enables an inventory of sterilized items to be maintained. Because the items need not be sterilized immediately prior to use, the capacity of the sterilizer apparatus may be based on average s~erile item useage of the medical Facility rather than peak usage.

~7;~
g With particular reference to FIGURE 2 and continuing reference to FIGURE 1, the module A is a hermetically sealed enclosure. A lid or cover 10 is opened to gain access to the interior of a body portion 12.
Interconnection means or fittings 14 enable the module to be selectively connected in a fluid exchanging relationship to the sterilizer unit B. Fluid check valves 16 are mounted in the interconnecting means to permit sterilant solution, rinse solution, and drying 10 gas to pass into and out of the module only while it is interconnected with the sterilizer B. A fluid level control means such as a standpipe 18 assures that fluids completely fill the module and that ambient air is expelled. The module is mounted at an angle and the 15 standpipe extends to the upper most point in the module to prevent air pockets. Concurrently with removal from the sterilizer, the check valYes close preventing ambient air contamination from entering the interior of the module. This enables the module and the sterilized 20 item or items contained therein to be removed from the sterilizer as a unit and stored in inventory.
Additional modules containing other items to be sterilized may be interconnected serially with the sterilizer B. After each item is sterilized, the item 25 and its encasing module are also inventoried. In this manner, the self-sealing modu]e enables an inventory of sterile devices to be maintained.
The module further includes a galvanic corrosion inhibiting means 20. In the preferred embodiment, an 30 electrical connection means 22 electrically connects metal portions o~ the item to be sterilized with an exterior electrical connector 24. One or more interior electrodes 26 are connected with an exterior electrical connector 28. Under a suitable electrical bias applied ~2~7377~

by the sterilizer unit B, any galvanic current through the sterilant solution is neutralized. Optionally, other forms of cathodic protection, such as a sacrificial anode, may be provided.
The interior electrodes 26 may be constructed of an electrically conductive material with lower electrical potential than the item. For stainless steel and brass items, satisfactory anode materials include zinc, magnesium, aluminum, or the like.
A reservoir 30 is mounted in the sterilizer unit B
such that the lowest surface of the reservoir is higher than the upper most surface of the module A. This enables fluid to ~low under gravity from the reservoir and completely fill the module. Optionally, the 15 reservoir may be mounted lower than the module and a pump provided. The reservoir includes an electrical heating means 32 for selectively heating liquids in the reservoir. A temperature sensor 34 monitors the temperature of the fluids in the reservoir. A
20 temperature control means 36 selectively controls the electrical power through a resistive heating element 38 to maintain preselected liquid temperatures within the reservoir.
In the preferred embodiment, the temperature control 25 means selectively heats a sterilant solution to 60C
(140F) and boils water to 132C (270F). A cooling means 40 selectively reduces the temperature of the liquids in the reservoir. Specifically, a cooling water valve 42 selectively controls the flow of tap water from 30 a water supply manifold or means 44 through a cooling coil 46. In a normal installation, the water manifold is connected with a sink or o~her water tap of the medical facility. In the preferred embodiment, tap water is sterilized by boiling at at least 132C and 35 cooled below 60C before rinsing to avoid thermal degradation of the sterilized items.

1~73~J~

The s~erilant solution is formed by mixing a sterilant concentrate with tap water. A sterilant dilution or inlet water control valve 50 and a check valve 52 connect the water supply 44 with the reservoir 30. A sterilant injection chamber 54 is interconnected between the sterilant dilution water valve 50 and the check valve 52 for selectively injecting a sterilant concentrate into received tap water. Further to the preferred embodiment, the sterilant injection chamber 54 receives a cartridge or ampule containing one or more components of a sterilant concentrate. Upon closing a cover 56 to the chamber, the sterilant cartridge is punctured such that the water may flow through the sterilant cartridge and wash the sterilant concentrate therefrom. The sterilant concentrate may be either a liquid, a solid, or combination thereof. In the preferred embodiment, the sterilant concentrate car~ridge includes more than one compartment for containing a hypochloride, a pH buffer, and a detergent 20 or surfactant.
Interconnecting tubing 60 interconnects the reservoir 30 and module receiving fluid connecting means 62. In the preferred embodiment, the module receiving connecting means include check valves 64 which close in the absence of a module to protect the interconnecting tubing from ambient contamination.
A tubing and module filling means or reservoir outlet valve 70, when open, selectively releases sterilant solution and rinse solution from the reservoir 30 to flow into and fill the interconnecting tubing 60 and the module A. When closed, the reservoir outlet valve 70 holds sterilant solution and other fluids in the interconnecting tubing 60 and the module A. The stand pipe 18 prevents air pockets and assures that all surfaces of the interconnecting tubing, module, and item to be sterilized are held in contact with the sterilant solution for a preselected duration.
A low level sensor 72 senses when the liquid level in the reservoir reaches substantially to the bottom o the reservoir When the liquid level reaches the bottom of the reservoir and before the liquid level clears the reservOir outlet valve 70, the low level sensor 72 10 closes the reservoir outlet valve 70 to trap and hold sterilant solution in the interconnecting tubing and module.
When the module A is mounted above the reservoir 30, a pump is provided in the interconnecting tubing 60.
15 The low level sensor 70 terminates operation of the pump sufficiently concurrently with the closing of the outlet valve 70 so that the interconnecting ~ubing and the pump chambers are completely filled with sterilant solution.
An air inlet valve 80 selectively interconnects the 20 interior of the reservoir 30 with a source of sterile air or other drying gas. An air sterilizing means 82, such as a sterilizing filter which removes particulates which are as large or larger than bacteria, sterilizes received ambient air. Optionally, other sterilizing 25 means may be utilized such as temperature, ozone, radiation, and the like. A heater 84 selectively heats the air to increase its drying power. An air pump 86 selectively supplies air under sufficient pressure to circulate the air or drying gas through the reservoir

3~ 30, the interconnecting tubing 60, and the module A. A
pressure relief valve 88 selectively vents air from the reservoir as the reservoir is filled.
A high f]uid level sensor 90 senses when the fluid completely fills in the reservoir 30 and the fluid level ~273774 reaches the top of the reservoir. The high fluid level sensor 90 closes the water inlet control valve 50 when the liquid completely displaces all air from the reservoir and plumbing in fluid connection therewith.
In this manner, the air inlet valve 80 is sterilized by steam as the rinse solution is heat sterilized. A
pressure relief valve 92 interconnects the reservoir B
with a drain 94 for permitting steam, excess water, or sterilant solution to be drained from the system. In a normal installation, the drain 94 is interconnected with the drain of a sink or other conventional plumbing.
When filling the module A and interconnecting tubing 60 with sterilant solution, a level control drain line 100 channels overflow sterilan~ solution from the standpipe 18 to the drain 94. At the end of the duration that sterilant solution is held in the interconnecting tubing and module, a drain valve 102 releases fluid from the module. The drain valve 102 selectively drains the sterilant and rinse solutions from the module through a siphon break 104 to the drain 94. At the end of the rinse cycle, a module empty sensor 106 senses that the module has been completely drained of liquid. After the module has been completely drained, the module low level sensor enables the air pump 86 and other portions of the drying assembly.
A printer 108 provides a printout of information concerning the sterilization process. In the preferred embodiment, the printer prints on a paper tape the date and time at which the sterilization was undertaken, the temperature of the sterilant solution as read by the temperature sensor 34 upon being introduced into the module, the duration which the sterilant was held in the module, the temperature to which the tap water was boiled and the duration of the boiling, and other system ,,...~.: .

1273~7~

parameters. The paper tape or other appropriate print out is retained with the module and the sterlized item to provide a permanent record of the parameters of the sterilization process.
A galvanic corrosion inhibiting means 110 includes a source 112 of a D.C. electric potential. A first electrical contact 114 interconnects the electrical potential with the first module exterior electric connector 24 and the item to be sterilized. A second 10 electric contact 116 interconnects the electric potential with the second module exterior electric connector 28 and the interior electrodes 26. A switch 118 connects the source of electric potential with the module while sterilant solution is therein and 15 disconnects the potential source other times. When the electrodes 26 are constructed of a sacrificial metal, the source of electrical potential may be omitted.
In operation, a contaminated device is closed in the module A and the module is plugged in to the sterilizer 20 unit B. A sterilant cartridge is placed in the sterilant injection chamber 54 and the chamber closed.
The sterilizer is now ready for automatic operation.
The sterilizer B first opens the water inlet control valve 50 which dilutes and, if applicable, dissolves components of the sterilant concentrate forming a sterilant solution. The sterilant solution passes into the reservoir B until the high level sensor 90 senses that the reservoir is completely filled.
The high level sensor 90 causes the inlet water 30 control valve 50 to close and the temperature control means 36 to heat the sterilant solution to 60C for two to three minutes. The reservoir outlet valve 70 opens allowing the warm sterilant solution ~o flow through and fill the interconnecting tubing 60 into the module A.
35 When the module is completely filled, excess sterilant solution flows through the standpipe 18 to the drain When the reservoir low level sensor 72 senses that the level of sterilant in the tank is almost to the bottom, the reservoir outlet valYe 70 is cause~ to close. Closing the reservoir outlet valve 70 traps and holds the sterilant in the interconnecting tubing C and a module A. The sterilant solution is held in the interconnecting tubing and module for a suffient duration to sterilize the tubing, the module, and the item, in the preferred embodiment a minimum of about 10 10 minutes. The whole duration is calculated such that the chances of a surviving life form is no greater than one in one million, that is, a sterility assurance level of 10-6. While the sterilant solution is in the module, switch 118 is closed causing a current flow between the 15 module electrode 26 and the item being sterilized to inhibit galvanic corrosion.
While the sterilant is being held in the module A
and interconnecting tubing 60, the water inlet valve SO
is again opened to fill the reservoir 30 with additional 20 tap water. The incoming tap water flows through the sterilant concentrate cartridge which has been fully emptied. Optionally, the same cartridge or another cartridge may include another chamber holding a rinse water treatment and the sterilizer unit B may channel 25 the incoming tap water therethrough. The treatment may include a salt, a pH buffer, a filter, or the like.
When the hi8h liquid level sensor 90 senses that the tap water has filled the reservoir completely, the water inlet control valve 50 is closed and the temperature 30 control means 36 causes the water to be heated to a sterilization temperature, e.g. 132C for at least five minutes. After the rinse water has been heat sterilized, the cooling water valve 42 is opened to reduce the temperature of the rinse water in the 35 reservoir 30 below 60C to avoid heat degradation of the sterilized device.

1~7377~

After the sterilization period, drain valve 102 and the reservoir outlet valve 70 are opened allowing the sterilant solution to drain from the module and allowing the rinse solution to rinse the interconnecting tubing 50, the module A, and the sterilized item with sterile rinse solution.
When the module is empty, the module low level sensor 106 senses that the sterilant solution and the rinse solution have been drained from the module. The air pump 86 and air heater 84 are actuated to supply a flow of hot air. The air sterilizing filter 82 removes living organisms and other particles of comparable size such that only sterile, warm air passes through the reservoir 30, the connecting tubing 60, the module A, and out the siphon break 104. The warm air may be circulated through the module for a sufficient time to cause complete drying of the device. Alternately, the module may include a liquid impermeable submicron sterilization filter which allows water vapor to pass out of the module without allowing bacteria and other potential contaminants to enter. If the module has such a permeable filter port, the module may be removed from the sterilizer before complete drying.
Although sterilization provides a greater assurance of patient protection from harmful life forms and is thus preferred, it is to be appreciated that the present invention is also applicable to disinfection.
Disinfection can be attained by using a less powerful antimicrobial agent than a sterilant, by using a more dilute sterilant, or by holding a sterilant in contact with surfaces to be disinfected for a shorter duration.
The foregoing apparatus and methods are equally applicable to sterilization and disinfection. The term "microbial decontamination" has been selected and is used herein generically to both sterilization and disinfection.

~273774 16a The invention has been described with reference to the preferred embodiment. Obviously modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such alterations and modifications insofar as they come within the scope of the appended claims or the equivalents thereof.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of microbially decontamination comprising:
changing both a chamber containing at least one item to be microbially decontaminated and tubing which interconnects the chamber with a rinse solution source with a liquid antimicrobial solution;
maintaining the antimicrobial solution in the chamber and the interconnecting tubing for a preselected duration, which preselected duration is sufficiently long to microbially decontaminate an interior of the chamber, the item, and the interconnecting tubing; and, rinsing the antimicrobial solution from the interconnecting tubing, the chamber interior, and the item with a microbially uncontaminated rinse solution from the rinse solution source.

2. The method as set forth in claim 1 further including mixing reagents and a dilution fluid to form the antimicrobial solution, the mixed antimicrobial solution having a microbe killing efficacy and the holding step having a duration which results in the item being at least disinfected.

3. The method as set forth in claim 1 further including mixing a reagent and a dilution fluid to form the antimicrobial solution, the antimicrobial solution having a sterilant concentration and the holding step having a duration such that the item is sterilized.

4. The method as set forth in claim 1 further including prior to the rinsing step, the step of heat sterilizing the rinse solution in the rinse solution reservoir.

5. The method as set forth in claim 4 further including cooling the heated rinse solution prior to the rinsing step.

6. The method as set forth in claim 1 further including passing a bacteria-free drying gas through at least the interconnecting tubing and the module to dry the item.

7. The method as set forth in claim 1 wherein the chamber is a detachable module and further including:
after the rinsing step, concurrently detaching the module from the interconnecting tubing and sealing the module from the atmosphere; and, storing the module and the item as a unit.

8. The method as set forth in claim 1 further including:
during the holding step, passing an electrical current between the item and an electrode in an electrical conductive relationship with the antimicrobial solution to inhibit the galvanic corrosion.

9. The method as set forth in claim 1 wherein the sterilant solution includes a hypochlorite, a buffer, a detergent, and water.

10. A method of sterilizing comprising:
enclosing an item to be sterilized in a module which is closed to the ambient atmosphere;
discharging a preselected dose of sterilant concentrate into a dilution fluid to form a sterilant solution;
filling the module with the sterilant solution and holding the sterilant solution in the module until the item is sterilized;

discarding the sterilant solution, whereby the sterilant solution is mixed fresh for each item;
passing a sterile rinse fluid into the module to rinse the sterilant solution from the item; and, storing the item in the module to retain the item sterile.

11. A method of disinfecting comprising:
enclosing an item to be disinfected in a module which is closed to the ambient atmosphere;
discharging a preselected dose of a reagent into a dilution fluid to form an antimicrobial solution;
filling the module with the antimicrobial solution and holding the antimicrobial solution in the module until the item is at least disinfected:
draining the antimicrobial solution from the module:
passing a microbially uncontaminated rinse fluid into the module to rinse the antimicrobial solution from the item:
and, storing the item in the module to retain the item disinfected.

12. A method of disinfection comprising:
immersing an item to be disinfected in a disinfectant solution:
inducing a current between the item and an electrode in the solution to inhibit galvanic corrosion of the item.

13. The method as set forth in claim 12 wherein the solution includes a hypochlorite, a buffer, and a detergent.

14. The method as set forth in claim 12 wherein the inducing step includes applying an electrical potential between the item and the electrode.

15. The method as set forth in claim 12 wherein the electrode is a sacrificial metal such that a galvanic current is induced between the current and the electrode.

16. A microbial decontamination apparatus comprising:
a chamber for containing at least one item to be microbially decontaminated;
a source of microbially uncontaminated rinse solution;
interconnecting tubing for connecting the rinse source and the chamber such that the rinse solution selectively passes from the rinse source to the chamber;
a means for selectively filling both the interconnecting tubing and the chamber with an antimicrobial solution; and, a means for selectively holding the antimicrobial solution in the interconnecting tubing and chamber for a preselected duration.

17. The apparatus as set forth in claim 16 wherein the chamber includes at least one electrode mounted therein for inhibiting the galvanic corrosion.

18. The apparatus as set forth in claim 17 further including a biasing means for providing an electrical bias between the electrode and the item to provide a corrosion neutralizing anticorrosive electromotive force therebetween.

19. The apparatus as set forth in claim 16 wherein the rinse source includes a reservoir and the chamber includes a module that is mounted completely below the reservoir such that fluid flows by gravity from the reservoir to the module.

20. The apparatus as set forth in claim 19 wherein the filling means includes:

a reservoir outlet valve connected between the reservoir and the interconnecting tubing for selectively permitting sterilant solution to pass from the reservoir into the tubing and for selectively blocking the flow of sterilant fluid therethrough, the outlet valve holding the fluid in the tubing with a siphon effect; and, a drain line connected with the module and extending substantially as high as a highest point of the module such that after the sterilant solution completely fills the module, excessive sterilant solution passes from the module through the drain line.

21. The apparatus as set forth in claim 16 further including an antimicrobial solution mixing chamber for selectively receiving ampules of a reagent that mixes with water to form the antimicrobial solution, the mixing chamber being operatively connected between a water inlet and the rinse source such that water passing from the water inlet through the mixing chamber mixes with the reagent forming the antimicrobial solution which passes into the chamber.

22. The apparatus as set forth in claim 16 further including a gas supply means for supplying microbially decontaminated gas for drying items in the chamber, the gas supply being operatively connected with the chamber.

23. The apparatus as set forth in claim 22 wherein the gas supply means includes an air pump for increasing the pressure of atmospheric air, a heater for heating the air to improve its drying power, and a submicron filter for filtering pathogenic life forms from the heated air.

24. A system for microbially decontaminating items to a disinfected or a sterile state and storing the items while retaining the disinfected or sterile state, the system comprising:
a plurality of modules, each capable of containing at least one item to be microbially decontaminated, each module including a plurality of fluid ports with automatic closure valves therein such that the module is hermetically sealed with the automatic closure valves are closed;
a plurality of interconnected fittings for selective interconnection with the module ports and for opening the module closure valves, one of the fittings being interconnected with a drain and another of the fittings being connected with interconnecting tubing for interconnecting the module with a rinse fluid source;
an antimicrobial solution means for selectively supplying an antimicrobial solution through the interconnecting tubing to the module; and, a means for selectively supplying a microbially uncontaminated rinsing solution from the rinse fluid source to the module.

25. A disinfection apparatus comprising:
a container for holding at least one item to be disinfected;
at least one electrode disposed in an electrically conductive relationship with a disinfectant solution received in the container.

26. The apparatus as set forth in claim 25 further including a source of electrical potential operatively connected with an electrically conductive portion of the item and the electrode for inhibiting galvanic corrosion.

27. The apparatus as set forth in claim 25 wherein the electrode is a sacrificial anode relative to electrically conductive portions of the item such that a galvanic current is induced which inhibits galvanic corrosion of the item.

28. A microbial contamination removing apparatus comprising:
a source of liquid rinse fluid;
a means operatively connected with the source for eliminating a microbial contamination from the liquid rinse fluid;
a chamber including a closure means which has opened and closed configurations therefor, wherein in the opened configuration, said chamber is opened to receive an item to be decontaminated in an interior thereof, and in the closed configuration, said chamber isolates the received item from the ambient atmosphere and other sources of microbial contamination;
interconnecting tubing connecting the source and said chamber;
a means for selectively holding liquid anti-microbial solution in both the interconnecting tubing and the chamber for a sufficient duration to decontaminate the chamber interior, the item, and the interconnecting tubing from the source to the chamber.

29. A method of microbial decontamination, the method comprising:
enclosing an item to be microbially decontaminated in a chamber interior which is isolated from microbial contamination from the ambient atmosphere;
causing an anti-microbial solution to flow into the chamber interior and an interconnecting flow path defined between a source of a rinse liquid and the chamber interior and direct fluid communication therewith;

retaining the antimicrobial solution in the chamber interior and the interconnecting flow path until the item, the chamber interior, the flow path, and the interior surfaces are free of microbial contamination, whereby freeing all surfaces between the rinse fluid source and the chamber of microbial contamination assures that the liquid rinse fluid will not carry microbial contaminants from contaminated surfaces into the chamber;
draining the antimicrobial solution from the chamber interior and the interconnecting flow path;
passing the liquid rinse fluid from the liquid rinse source only in contact with the microbial contamination-free flow path surfaces into the chamber to rinse the item;
draining the liquid rinse fluid from the chamber interior.

30. A method of removing microbial contamination from medical instruments, the method comprising:
disposing a medical instrument to be freed from microbial contamination in a chamber interior;
closing the chamber interior to penetration by microbial contaminates;
filling interconnecting tubing from the chamber interior to a rinse solution source and the chamber interior with a liquid antimicrobial agent;
retaining the liquid antimicrobial agent in the chamber interior and the interconnecting tubing for a preselected duration, which preselected duration is sufficiently long to eliminate microbial contamination in the chamber interior, of the medical instrument, and in the interconnecting tubing;
passing a microbial contaminant-free liquid rinse solution from the rinse solution source only through the microbial contamination-free interconnecting tubing into the microbial contamination-free chamber interior to rinse the liquid antimicrobial agent from the interconnecting tubing, the module, and the medical instrument, whereby the liquid rinse solution passes only in contact with microbial contamination-free surfaces to prevent microbial contamination of the liquid rinse solution.

31. A method of removing microbial contamination from items, the method comprising:
a) enclosing an item to be freed of microbial contamination in an interior of a module which is closed to penetration of microbial contaminants from the ambient atmosphere;
b) removably attaching the module with tubing that connects the module with a source of microbial contaminant-free rinse liquid;
c) causing a liquid antimicrobial solution to flow into and remain in contact with the module interior and the tubing which connects the module with the source of rinse liquid until the item and the module interior are free of microbial contamination;
d) draining the liquid antimicrobial solution from the module interior;
e) passing a microbial contamination-free rinse liquid from the source thereof into the module interior to rinse the item;
f) detaching the module while maintaining the module closed to microbial contaminants;
g) storing the item in the module to retain its microbial contaminant-free condition.

32. A method of making an item free of microbial contamination, the method comprising:
enclosing the item in a chamber which is isolated from microbial contamination from the ambient atmosphere;

providing interior surfaces which define a liquid rinse flow path between the chamber and a source of microbial contamination-free rinse liquid;
causing an antimicrobial solution to flow into the chamber and into all flow path interior surfaces which define the interconnecting flow path from the liquid rinse source into the chamber and every interior surface in direct fluid communication therewith;
retaining the antimicrobial solution in the chamber and the interior surfaces until the interior surfaces, the item, and the chamber are free of microbial contamination, whereby freeing all surfaces between the rinse fluid source and the chamber of microbial contamination assures that the liquid rinse fluid will not carry microbial contaminants from contaminated surfaces into the chamber;
draining the antimicrobial solution from the chamber and the interconnecting flow path;
passing the liquid rinse fluid from the liquid rinse source only in contact with the microbial contamination-free flow path surfaces into the chamber to rinse the item;
draining the liquid rinse fluid from the chamber.