WO1998007453A1 - Surveillance et gestion en temps reel de procedes de sterilisation a l'aide de sondes de detection d'oxygene - Google Patents

Surveillance et gestion en temps reel de procedes de sterilisation a l'aide de sondes de detection d'oxygene Download PDF

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Publication number
WO1998007453A1
WO1998007453A1 PCT/US1997/014467 US9714467W WO9807453A1 WO 1998007453 A1 WO1998007453 A1 WO 1998007453A1 US 9714467 W US9714467 W US 9714467W WO 9807453 A1 WO9807453 A1 WO 9807453A1
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WO
WIPO (PCT)
Prior art keywords
sterilant
concentration
oxygen
sterilizer
sterilization
Prior art date
Application number
PCT/US1997/014467
Other languages
English (en)
Inventor
George E. Sparber
Carl. J. Winschel
Jaime Diaz
Matthew L. Casey
Original Assignee
American Sterilizer Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by American Sterilizer Company filed Critical American Sterilizer Company
Publication of WO1998007453A1 publication Critical patent/WO1998007453A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/26—Accessories or devices or components used for biocidal treatment
    • A61L2/28—Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/18—Liquid substances or solutions comprising solids or dissolved gases
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/20—Gaseous substances, e.g. vapours
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/24—Apparatus using programmed or automatic operation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/411—Cells and probes with solid electrolytes for investigating or analysing of liquid metals

Definitions

  • the present invention is concerned with direct, real-time monitoring and control of sterilant concentration in sterilization processes employing sterilants that produce measurable free oxygen as a breakdown product .
  • the sterilizer control system may then operate various sterilizer components, such as pumps, valves, etc., to control the amount of liquid hydrogen peroxide delivered to the vaporizer in order to maintain the desired theoretical concentration of sterilant gas/vapor in the chamber, while avoiding condensation due to vapor saturation.
  • various sterilizer components such as pumps, valves, etc.
  • the present invention takes advantage of the fact that certain sterilants, such as vapor hydrogen peroxide, peracetic acid and other peroxygen compounds, naturally decompose during sterilization processes to form free oxygen according to the equation:
  • Oxygen sensors are a known and relatively inexpensive technology for measuring concentrations of oxygen by employing solid oxide electrolyte cells that have the ability to conduct electrical current by means of mobile oxygen ions.
  • zirconium dioxide and titanium dioxide sensors have been used as galvanic cells to sense the oxygen concentration at high temperatures (approximately 350°C to 850 °C) in automobile exhaust gas in the absence of water. Measurement of the rate of oxygen generation in determining the stability of liquid peroxygen compounds has been described.
  • gas flow sensors measure oxygen in a gas flow from a liquid sample maintained at 100°C, or up to the boiling point of the sample, over a time period of about one hour.
  • such a system is sensitive to slight changes in temperature and/or barometric pressure and also preferably employs a water condenser to exclude water vapor from the sensor.
  • oxygen sensors have not been described for measuring oxygen concentrations under subatmospheric conditions or in sterilization processes having wide variations m pressure, m which sterilants may also contain water vapor, and m which temperatures may be maintained well below 100°C. Further, oxygen sensors have not been described for real-time monitoring of the concentration of oxygen- forming sterilants, such as peroxygen liquid or gas sterilants, within a sterilization chamber during a decontamination or sterilization cycle Moreover, until the present invention, real-time control of the concentration of liquid or gas sterilants based on monitoring of free molecular oxygen produced by the sterilant during a sterilization cycle, has not been described.
  • an apparatus for real-time monitoring and control of a concentration of a liquid or gaseous sterilant in a sterilizer during a sterilization cycle
  • a control system controls environmental conditions and the concentration of sterilant in the sterilizer
  • a sterilizer probe supplies the control system with information about the sterilization cycle.
  • the sensor probe includes an oxygen sensing cell m fluid communication with the sterilant in the sterilizer for continuous, real-time measurement of the concentration of free oxygen in the sterilizer during the sterilization cycle.
  • the oxygen sensing cell produces an electrical signal which varies m accordance with the free oxygen concentration
  • the control system receives the electrical signal from the sensor probe and compares the sensed oxygen concentration with an electronically stored, reference sterilant range
  • the control system controls at least one of the sterilant concentration and the environmental conditions in accordance with the comparison .
  • a method of monitoring a sterilant cycle is provided.
  • a liquid or gaseous sterilant is supplied to a sterilizer.
  • Environmental conditions m the sterilizer are monitored and at least environmental conditions are adjusted m accordance with the monitoring
  • a concentration of free oxygen m the sterilizer is measured continuously and m real-time during the sterilization cycle
  • the monitored free oxygen concentration is compared with an electronically stored reference concentration range
  • At least one of the environmental conditions and a concentration of the sterilant is controlled in accordance with the comparison.
  • One advantage of the present invention is that it provides real-time control of sterilization processes.
  • Another advantage of the present invention resides in its direct measurement of sterilant concentration
  • FIGURE 1 is a schematic representation of a zirconia oxygen sensor as employed in the invention.
  • FIGURE 1A is a schematic representation of the migration of oxygen ions through the solid electrolyte from the region of higher to lower free oxygen concentration
  • FIGURE 2 is schematic representation of a typical vapor hydrogen peroxide sterilization system employing an oxygen sensor in the invention.
  • FIGURE 3 is a schematic representation of a sterilization cycle employing vapor hydrogen peroxide at subatmospheric pressures m a closed sterilization chamber
  • FIGURE 4 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 at a concentration of one gram of vaporized hydrogen peroxide at 50°C.
  • FIGURE 5 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 at a concentration of two grams of vaporized hydrogen peroxide at 50°C.
  • FIGURE 6 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 at a concentration of three grams of vaporized hydrogen peroxide at 50°C.
  • FIGURE 7 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 at a concentration of four grams of vaporized hydrogen peroxide at 50°C.
  • FIGURE 8 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 at a concentration of five grams of vaporized hydrogen peroxide at 50°C.
  • FIGURE 9 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 employing one gram of water vapor at 50°C.
  • FIGURE 10 is a plot of voltage readings employing the zirconia oxygen sensor during the cycle of FIGURE 3 employing five grams of water vapor at 50 °C.
  • An oxygen sensor is employed in the invention to continuously monitor, in real-time, the concentration of free oxygen produced by sterilants, such as vapor hydrogen peroxide peracetic acid, that naturally decompose during sterilization processes to form free oxygen according to the equation:
  • the concentration of free oxygen in the sterilization system during the sterilization cycle is directly proportional to the concentration of the hydrogen peroxide vapor in the chamber.
  • the greater the concentration of hydrogen peroxide in the sterilizer the greater the concentration of free oxygen that will be produced as a breakdown product.
  • the electrical signal produced by the oxygen sensor in response to the free oxygen in the sterilization system is preferably voltage and is inversely proportional to the free oxygen and, thus, is also inversely proportional to the concentration of sterilant in the system.
  • a calibration curve may be constructed by predetermining the voltage produced by different concentrations of sterilant. During a sterilization cycle, the concentration of sterilant may then be continuously measured in real-time as indicated by the voltage output of the sensor cell.
  • a preferred oxygen sensor is a heated zirconia oxygen sensor 10, known in the art, and employing zirconium dioxide as a solid-state electrolyte in a galvanic cell.
  • a typical heated zirconia oxygen sensor suitable for use in the invention is an automotive oxygen sensor available from the Allied Signal Corporation, Autolite Division, Fostoria, Ohio.
  • oxygen sensors other than the heated zirconia sensor or the titania sensors may be used to measure the oxygen concentration, without departing from the spirit and scope of the invention.
  • a zirconia oxygen sensor requires reference air to enter the oxygen sensor.
  • other oxygen sensors suitable for use in the invention such as titania oxygen sensors, may not require reference air.
  • the heated area of the zirconia sensor is small enough that no appreciable heat -induced breakdown of the sterilant occurs.
  • a typical zirconia oxygen sensor 10 comprises a solid zirconium dioxide electrolyte 12 which is coated on the inner surfaces and outer surfaces with porous platinum inner electrode 14 and outer electrode 16, respectively.
  • the zirconium dioxide may contain a small amount of other substances, such as yttrium oxide, order to reduce its electrical resistance and provide structural stability
  • the sensor is heated by a heating means (not shown) m order to provide optimum sensitivity.
  • the sensor 10 has a housing 18 that is sealmgly mounted n a wall 20 of a sterilization chamber 24 and/or m a load-simulation device (not shown, described in our copending U.S. Patent Application, Serial No 08/602,515. All references to the sensor as employed a sterilization chamber are intended to include the sensor as employed in a load- simulating device
  • the interior 22 of the sensor 10 is open to the atmosphere outside of the chamber wall 20, such that the inner platinum electrode 14 is in fluid communication with atmospheric oxygen
  • the electrolyte 12 and the outer electrode 16 are enclosed (not shown) within the housing 18 and are not in contact with atmospheric oxygen
  • the outer electrode 16 is m fluid communication w th sterilant in the sterilization chamber 24 and is exposed to free oxygen produced within the chamber 24
  • oxygen ions are formed on one electrode and migrate through the oxide electrolyte from the region of higher to the region of lower oxygen concentration
  • FIGURE 1A during a sterilization cycle employing an oxygen-producmg sterilant at subatmospheric pressure, oxygen ions migrate through the electrolyte 12 from electrode 14 which is exposed to atmospheric air, to electrode 16 which is exposed to a lower free oxygen content the chamber environment .
  • the sensor is powered by a direct current (DC) power supply, observing correct polarity
  • the amount of power provided to the sensor varies according to the type of the sensor employed
  • a typical heated zirconia oxygen sensor 10 may have a power supply of 20 volts DC at 2 amperes to provide power to the heater, and a typical self -heating titania oxygen sensor may have a power supply of 14 volts.
  • electrode 14 is in electrical connection with a sensor signal plus (+) electrical line 32 which measures the voltage of the current supplied to the sensor.
  • Electrode 16 is in electrical connection with housing 18 that acts as a ground or sensor minus (-) electrical line 30.
  • any other type of signal or ground device suitable for acting as a signal plus line 32 or a sensor minus line 30, as known in the art, may be employed in the invention.
  • the flow of oxygen ions across the electrolyte 12 creates a measurable electromotive force or voltage from the signal plus line 32 to the signal minus line 30, that is inversely proportional to the concentration of free oxygen in the chamber 24.
  • the oxygen partial pressure inside the chamber is small, the oxygen ion flow from the inner electrode 14 to the outer electrode 16 is large, resulting in the possible development of up to about 0.9 to 1 volt.
  • the oxygen partial pressure inside the chamber is large, the ion flow is inhibited, and may result in development of voltage as low as 50 millivolts or less.
  • the voltage is thus inversely proportional to the concentration of free oxygen in the chamber.
  • the voltage is inversely proportional to the sterilant concentration at any time during the cycle.
  • the voltage developed by the cell may be measured by any means 34, including a voltage meter, known in the art.
  • the voltage may be amplified by known means to provide a greater signal. As described further below, the voltage signal is preferably transmitted to the sterilizer control system for real-time control of the sterilant concentration and/or to a data collection unit or parametric release monitoring system.
  • the oxygen sensor employed in the invention is sensitive to and provides accurate readings of free oxygen/sterilant concentration in sterilization systems employing subatmospheric conditions, at temperatures from about 4°C to about 100°C, and in which such environmental conditions as relative humidity, temperature, pressure and air flow rates may change dramatically in the sterilization system during a single sterilization cycle.
  • sterilization cycles include, but are not limited to, those employing vacuum conditions with or without admission of air during the exposure phase.
  • accurate real-time measurement of free oxygen/sterilant concentration is obtained during a cycle phase wherein the sterilant is exhausted from the sterilizer after the exposure phase and that may include aeration of the sterilizer.
  • an oxygen sensor 10 is placed in a sterilization system for real-time monitoring and control of sterilant concentration during a sterilization cycle employing a peroxygen sterilant, such as vapor hydrogen peroxide and water vapor, under subatmospheric conditions.
  • a typical sterilization system employing vapor hydrogen peroxide sterilant comprises a sterilization or decontamination enclosure or chamber 50 having a sealable door 52, a sterilant supply inlet line 53 which may also connected to an air inlet line (not shown) , an inlet valve 54 for admitting sterilant and/or air, a chamber drain line or exhaust outlet line 55, and a chamber outlet valve 56 connected to a vacuum pump 57.
  • a hydrogen peroxide gas sterilization system another oxygen generating liquid or gas sterilization system could be represented differently without departing from the spirit and scope of the invention.
  • An oxygen sensor probe 10 or a plurality of sensor probes 10A, 10B may be located within the chamber or removably and sealably connected to a chamber wall 59 or chamber drain/exhaust outlet wall 60 with the sensor in fluid communication with sterilant in the chamber 50 to measure the concentration of the free oxygen produced as a breakdown product of the sterilant in the chamber.
  • Sensor probes may additionally or alternatively be located in another area of the sterilization system, such as in a line 53 leading to the sterilant supply/air inlet valve 54 or in a line 58 leading from the outlet valve 56.
  • a single oxygen sensor probe in fluid communication with the sterilant is sufficient to provide real-time sterilant concentration values.
  • the sterilant concentration oxygen sensing cell may be located in a load-simulation device for real-time monitoring and control of the concentration of a sterilant in a load and for parametric release of the load when the sterilization parameters, including sterilant concentration have been met.
  • liquid sterilants such as aqueous hydrogen peroxide
  • the sterilization system illustrated in FIGURE 2 also includes sensors (not shown) for measurement of system environmental parameters, such as resistance temperature detectors (RTDs) or thermocouples for temperature monitoring, pressure transducers for pressure monitoring, humidity sensors for monitoring relative humidity, and air velocity meters for measuring air flow rates.
  • RTDs resistance temperature detectors
  • thermocouples for temperature monitoring
  • pressure transducers for pressure monitoring
  • humidity sensors for monitoring relative humidity
  • air velocity meters for measuring air flow rates.
  • Each oxygen sensor probe 10 comprises an oxygen sensing cell 120 in fluid communication with a sterilant in a sterilizer for continuously measuring the concentration of free oxygen produced in the sterilizer, usually as a breakdown product of the sterilant, during a sterilization cycle.
  • the sensing cell produces an electrical signal proportional to the free oxygen concentration and proportional to the sterilant concentration value.
  • the signal is voltage and is inversely proportional to the free oxygen concentration and inversely proportional to the sterilant concentration m the sterilizer
  • the voltage signal may be amplified by known means.
  • the signal is preferably transmitted to a sterilizer control system 62 via a transmitting unit 122. However, the voltage signal may also be transmitted to an intermediate data collection unit 66 and/or a parametric release monitoring system.
  • the transmitted signal is read by the sterilizer control system 62 which then sends an input signal to a process control system 64. Based on this input signal, the process control system 64 provides output instructions to operate electrically operated valves, pumps, etc., which in turn control various phases of the sterilization cycle, including delivery of liquid or gas sterilant during the exposure phases or removal of the sterilant during exhaust or purge phases .
  • the sterilizer control system 62 is programmed to store a predetermined reference sterilant concentration range, to receive the electrical signal representing the sterilant concentration value, and to compare the received concentration value to the stored reference sterilant concentration range.
  • the sterilizer control system 62 is also programmed to indicate acceptable sterilization conditions when the received sterilant concentration value falls within the reference sterilant concentration range, and to signal the process control unit 64 to change the sterilant concentration when the received sterilant concentration value falls outside the reference sterilant concentration range.
  • the process control unit 64 directs the operation of control means, such as heaters, valves, pumps, timers, etc., real-time to bring the sterilant concentration into the reference range
  • the process control unit 64 preferably comprises means to admit sterilant into the chamber, means to exhaust sterilant from the chamber and/or means to change an environmental parameter, such as temperature, pressure, relative humidity, time, air flow velocity and the like, m the sterilizing system
  • the sterilant concentration is controlled and maintained within the reference sterilant concentration range for a period of time sufficient to achieve sterilization.
  • the sterilizer control system 62 may be any system including, but not limited to, a microprocessor or a logic circuit that is programmed to receive the sensed concentration value and also to control the value of the concentration in real-time during the sterilization cycle by governing the process control unit 64.
  • predetermined target processing conditions inside the sterilization system may be maintained during all phases of the sterilization cycle, including the exposure to sterilant phase and the exhaust/purge phase.
  • the semiconductor sensor module transmitting unit 122 transmits an analog signal representing the sterilant concentration value in real-time to an external microprocessor 66 intermediate to the sterilizer control system 62.
  • an intermediate processor 66 preferably has the capability of data storage, data display, and alarm capabilities separate from the sterilizer control system 62. Data from the intermediate processor may then be sent to the sterilizer control system and also may be retained as a permanent record of sterilization parameters throughout the sterilization process.
  • the sensor module 10 continues to provide real-time monitoring of the sterilant concentration, and the sterilizer control system 62 continues to signal the process control unit 64 to operate valves, pumps, etc., to exhaust and/or aerate the system until all the sterilant is removed from the sterilizer or is at an acceptable level to end the sterilization process.
  • the pressure in the chamber typically alternates between deep vacuum and pressure rises due to admission of air.
  • the following examples illustrate the efficacy of a zirconia oxygen sensor in monitoring the concentration of vapor hydrogen peroxide in real-time during a sterilization cycle at subatmospheric pressures.
  • the sterilization cycle employed is schematically illustrated in FIGURE 3.
  • the cycle employs an evacuation phase, a sterilant exposure phase and a sterilant exhaust/purge phase.
  • the cycle begins by evacuating a sterilization chamber to subatmospheric pressure PI.
  • Sterilant is then admitted into the chamber for time Tl, raising the pressure in the chamber to P2.
  • T2 During a hold period T2 , the sterilant is allowed to permeate the chamber.
  • Air is then admitted into the chamber for a time period T3 , during which the pressure is raised to the subatmospheric level P3.
  • a hold period T4 allows sterilization to occur. This cycle constitutes one "pulse" .
  • an exhaust/aeration phase removes residual sterilant from the chamber.
  • the oxygen sensor employed in the examples is an automotive heated zirconia oxygen sensor, model number K109H4, obtained form Allied Signal Corporation, Autolite Division, Fostoria, Ohio and attached to a power supply of 20 volts DC and 2 amperes.
  • the sensor minus line and the sensor plus signal line of the sensor were attached to a Fluke Hydra Data collection device, manufactured by Fluke Company, Seattle, Washington, and the data plotted using a data base program, Quatro Pro, manufactured by Borland International, Scotts Valley, CA.
  • Vapor hydrogen peroxide sterilant was produced from food grade 35% liquid hydrogen peroxide that was injected into a vaporizer fluidly connected to the sterilization chamber.
  • Other grades and concentrations of liquid hydrogen peroxide, such as 31% electronic grade may be employed without departing from the scope of the invention, and the oxygen sensors calibrated accordingly.
  • the sterilant exposure cycle of FIGURE 3 was employed at a temperature of 50°C as follows: A closed sterilization chamber was evacuated to a subatmospheric pressure of about 1 Torr over a time period of about 150 seconds. Vaporized hydrogen peroxide was then admitted into the chamber for about 25 seconds, resulting in a rise in pressure to about 36 Torr. A chamber leak test, as is known in the art, was then conducted during the first exposure pulse, but not in subsequent exposure pulses. A hold period of about 60 seconds followed, during which the sterilant was allowed to permeate the chamber. Air was then admitted to the chamber over a period of 10 seconds, producing a rise in pressure to about 150 Torr. A hold period of 10 seconds was followed by a reevacuation of the chamber to 1 Torr. The above sequence of evacuation, exposure and reevacuation constituted one "exposure pulse" .
  • FIGURES 4, 5, 6, 7 and 8 illustrate plots of voltage generated by the zirconia oxygen sensor during six exposure pulses employing differing initial hydrogen peroxide concentrations of 1 gram, 2 grams, 3 grams, 4 grams and 5 grams, respectively.
  • the series of six exposure pulses was followed by eight exhaust/purge pulses, each of which constituted an evacuation to about 10 Torr and an aeration wherein air was admitted into the chamber to produce a rise in pressure to about 500 Torr.
  • the sterilizer control system is programmed with the calibration curve to read the voltages generated throughout a sterilization cycle and calculate the equivalent concentration of hydrogen peroxide. For example, although vapor hydrogen peroxide produces water or water vapor as another breakdown product, the effects of the water upon the voltage readings were negligible, as illustrated in FIGURES 9 and 10 and TABLE 2. To test the effects of water, one gram or five grams of water vapor only were injected into the chamber and subjected to an identical sterilization cycle as that employed for hydrogen peroxide .
  • the method of the invention proceeds by the steps of exposing the sensing cell to the sterilant during a sterilization cycle; continuously sensing the concentration of free oxygen in the sterilizer; continuously transmitting an electrical signal representing a sensed sterilant concentration to the sterilizer control system; and controlling the sterilant concentration in real-time during the sterilization cycle.
  • the method preferably further comprises the steps of maintaining the sterilant concentration value within the reference sterilant concentration range for a period of time sufficient to achieve sterilization.
  • the method preferably further comprises the steps of exhausting the sterilant from the sterilizer when the sterilization is achieved.

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Abstract

L'invention porte sur un système et un procédé de surveillance et de gestion en temps réel de la concentration d'un stérilisant dégageant de l'oxygène pendant toutes les phases d'un cycle de stérilisation. Une sonde de détection d'oxygène (10) mesure l'oxygène libre dans une chambre de stérilisation (24). Ladite sonde utilise de préférence un électrolyte d'oxyde solide (12), par exemple du bioxyde de zirconium ou de titane. La sonde produit un signal électrique inversement proportionnel à la concentration en oxygène libre et en stérilisant. Le signal est transmis en temps réel au système de gestion du stérilisateur (62, 64) en vue du réglage des paramètres nuisant à l'environnement. Le système de gestion maintient les niveaux de concentration des stérilisants dans des limites acceptables pendant des périodes suffisantes pour assurer l'efficacité de la stérilisation compte tenu de la concentration en stérilisants mesurée. Le système de gestion éjecte le stérilisant à la fin du cycle et gère d'autres paramètres de l'environnement.
PCT/US1997/014467 1996-08-20 1997-08-18 Surveillance et gestion en temps reel de procedes de sterilisation a l'aide de sondes de detection d'oxygene WO1998007453A1 (fr)

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US08/700,292 1996-08-20

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2060277A1 (fr) * 2007-11-14 2009-05-20 INDAG Gesellschaft für Industriebedarf mbH & Co. Betriebs KG Dispositif et procédé de stérilisation
JP2016529025A (ja) * 2013-08-30 2016-09-23 アメリカン ステリライザー カンパニー 滅菌サイクルの実行方法
US10905786B2 (en) 2017-03-27 2021-02-02 Regeneron Pharmaceuticals, Inc. Sterilisation method
DE102022207423A1 (de) 2022-07-20 2024-01-25 Christof-Herbert Diener Indirekte Überwachung einer Wasserstoffperoxidkonzentration

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0384535A2 (fr) * 1989-02-22 1990-08-29 Shikoku Kakoki Co., Ltd. Dispositif pour l'alimentation de peroxyde d'hydrogène pour la stérilisation
WO1997004816A1 (fr) * 1995-07-27 1997-02-13 American Sterilizer Company Dispositif de commande et de surveillance en temps reel et procede de decontamination en phase vapeur au peroxyde d'hydrogene
EP0774263A1 (fr) * 1995-11-20 1997-05-21 Mdh Limited Procédé et appareil pour la stérilisation par la vapeur de peroxyde d'hydrogène

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0384535A2 (fr) * 1989-02-22 1990-08-29 Shikoku Kakoki Co., Ltd. Dispositif pour l'alimentation de peroxyde d'hydrogène pour la stérilisation
WO1997004816A1 (fr) * 1995-07-27 1997-02-13 American Sterilizer Company Dispositif de commande et de surveillance en temps reel et procede de decontamination en phase vapeur au peroxyde d'hydrogene
EP0774263A1 (fr) * 1995-11-20 1997-05-21 Mdh Limited Procédé et appareil pour la stérilisation par la vapeur de peroxyde d'hydrogène

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2060277A1 (fr) * 2007-11-14 2009-05-20 INDAG Gesellschaft für Industriebedarf mbH & Co. Betriebs KG Dispositif et procédé de stérilisation
JP2016529025A (ja) * 2013-08-30 2016-09-23 アメリカン ステリライザー カンパニー 滅菌サイクルの実行方法
US10905786B2 (en) 2017-03-27 2021-02-02 Regeneron Pharmaceuticals, Inc. Sterilisation method
US10918754B2 (en) 2017-03-27 2021-02-16 Regeneron Pharmaceuticals, Inc. Sterilisation method
DE102022207423A1 (de) 2022-07-20 2024-01-25 Christof-Herbert Diener Indirekte Überwachung einer Wasserstoffperoxidkonzentration

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