Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
  • G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
  • G01N31/222—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating moisture content
• • 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—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
  • A61L2/26—Accessories
  • A61L2/28—Devices for testing the effectiveness or completeness of sterilisation or disinfection, e.g. indicators which change colour

Definitions

• THIS INVENTION concerns a device for testing the efficiency of autoclaves such as those used in hospitals for sterilizing porous loads, and for detecting the presence of air in such a system, and is particularly concerned with an indicator sheet for use in such a device, which provides a visual indication of the presence of air and/or other substances under steam sterilizing conditions.
• Porous loads are sterilized by subjecting them to saturated steam at a temperature of between 134°C and 138°C for a period of not less than 3 minutes.
• saturated steam In order to ensure correct sterilizing conditions, the steam must penetrate unhindered to all parts of the load. This can be achieved only if all of the air is first removed from the sterilizer vessel and from its load, which is accomplished typically by a process of evacuation and steam flushing of the sterilizing vessel and its load.
• test pack is processed in the sterilizer and the satisfactory result would show an even change in appearance across the whole of the indicator sheet, whereas the presence of air in the stack is indicated by a failure of the indicator to change its appearance in certain areas, usually at the centre.
• the test must be carried out daily before the sterilizer is used for the production of sterile porous loads.
• Such indicators conventionally may consist of so-called autoclave tape which is placed across a sheefc, of paper * , and reacts visibly to the presence of air and moisture under steam sterilizing conditions.
• certain manufactured sheets having an indicator pattern printed thereon from a substance which, again, reacts by changing its appearance under steam sterilizing conditions. It has been found that these conventional types of indicator suffer from the disadvantage that their appearance is affected by the presence of excessive moisture during the test, and this can lead to a false reading when attempting to detect the presence of air. In some cases, this can have the effect of a substance from the tape or sheet being transferred onto the material of the pack which in turn further affects the appearance of the indicator producing still further misleading results.
• One kind of device for detecting the presence of air in a steam sterilizer comprises a first porous mass of at least substantially man-made material, a second porous mass of a similar material, an indicator adapted to undergo a visual change under moist heat sterilizing conditions and sandwiched between the masses thus to be in intimate contact therewith, and means for removably holding the masses and indicator in close superimposed relationship, said means being permeable to allow the free passage of air and steam to the external surfaces of the porous masses.
• an indicator sheet for an autoclave test pack having across a substantial part of at least one of its surfaces, a pattern of indicator markings comprising at least one substance adapted to provide an indicatation of the presence of air and/or excessive moisture under steam sterilizing conditions such that, under such conditions, the presence of air and/or excessive moisture becomes evident and individually identifiable.
• Fig. 1 is a perspective view of a device made in accordance with the invention.
• Fig 2 is an exploded view of some of the constituent parts thereof.
• one form of device for detecting the presence of air in a steam sterilizer comprises first and second porous masses 10 and 11 each formed from a stack of single sheets of a man-made woven or non-woven material such as spun bonded polypropylene having a weight in the region of 50 - 150 (and typically in the region of 100) grams per square metre. Each mass contains an appropriate number (typically between 60 and 300) of such sheets arranged in close superimposed relationship. Sandwiched between the masses 10 and 11 is an indicator sheet 12 bearing indicator markings 14 adapted to undergo a visual change during a test.
• a man-made woven or non-woven material such as spun bonded polypropylene having a weight in the region of 50 - 150 (and typically in the region of 100) grams per square metre.
• Each mass contains an appropriate number (typically between 60 and 300) of such sheets arranged in close superimposed relationship.
• Sandwiched between the masses 10 and 11 is an indicator sheet 12 bearing indicator markings 14 adapted to undergo a visual change during a test.
• the markings 14 are such that after a test has been carried out to detect the presence of air under steam sterilizing conditions, there will be a clear indication on the sheet of the presence of air and/or excessive entrained moisture in the applied steam. Since excessive moisture can produce a false reading, perhaps suggesting to the operator the presence of air when no air is present, it is necessary to detect the presence of droplets of entrained moisture in the otherwise saturated steam, and for this to be visible on the indicator sheet as distinct from any indication of the presence of air.
• the pattern of indicator markings printed or otherwise placed on backing sheet 12 is arranged to cover substantially the whole surface area of at least one face of the sheet and consists of at least one substance which is capable of providing separately identifiable indications of the presence of air and excessive moisture.
• a cover sheet 12a of a porous and absorbent material such as paper may be interposed between each face of sheet 12 and the adjacent surface of the mass 10 or 11.
• This may take the form of unglazed paper (bond) of weight typically 80g per square metre.
• the masses 10 and 11, and indicator 12 are placed in close superimposed relationship into a closable box or clamp 13 as a close fit therewithin.
• the clamp applies a slight compressive force to its contents to ensure that they are firmly held together.
• the clamp may be of stainless steel or plastics, and allows free access of air and steam to the test pack.
• the pack is constructed in a manner which permits use for a number of successive tests, for example, up to 30 but preferably 10-15.
• the pack when assembled is approximately cuboid and it has a side dimension typically in the region of 5 -
• the material from which the masses 10 and 11 are produced shall not give rise to exothermic reactions when hydrated and must exhibit air/steam penetration characteristics similar to those of Huckaback towels which comply with British Standard BS 1781.
• the markings -14 are formed from a printed substance which may consist of a single substance which changes colour or other aspects of its appearance in the presence or absence of air.
• any tendency for the substance to transfer from one sheet to another can be prevented by coating of the lead carbonate ink with a moisture-impervious substance such as varnish. Thus protected, it is insoluble.
• the sheet 12 has a pattern of radial lines projecting from a central position towards the edges.
• Each line may be "between 0.25 cm and 2 cm in width and printed using a lead carbonate ink.
• the lines may be of uniform thickness or tapering towards the centre. Certain selected and appropriately indicated ones of these lines can be protected against transfer in the presence of excessive moisture whilst others are left unprotected. This may be by pre-encapsulat ion or after- coating of the ink using a moisture-impervious, for example, polymeric substance.
• the shape and arrangement of the lines or other markings across the surface of the sheet is to some extent arbitrary but should extend substantially across the entire surface so that when subjected to steam sterilizing conditions in a test pack of the kind described above the presence of air would be visible as areas where the ink is unchanged or only partially changed, whilst the presence of excessive moisture would be visible by way of transfer of the unprotected markings in those areas when excessive moisture is present.
• the sheet may be some 30 cm by 12 - 15 cm and folded to be approximately square with a side dimension in the region of 12 - 15 cm so that it can be placed in the test pack with two opposed marked surfaces.
• the base sheet upon which the "markings are printed is preferably of a porous material such as paper, and in use this may be placed in the pack with cover sheets of similar material super-imposed on both marked surfaces as illustrated,
• the marked indicator sheet is preferably enclosed within an envelope of porous material such as spun bonded polypropylene or cellulosic material such as cotton or similar fabrics, or compressed paper or board-like material.
• porous material such as spun bonded polypropylene or cellulosic material such as cotton or similar fabrics, or compressed paper or board-like material.
• Substances other than lead carbonate ink may be used provided that they are capable of indicating the presence of air and/or excessive moisture under steam sterilizing conditions.
• One example might be amino acid compositions containing an indicator which changes from yellow to blue in the absence of air but from yellow to brown in the presence of air. Markings of such a material may be applied to the sheet in conjunction with one or more other materials indicating the presence of excessive moisture.
• the porous masses when assembled, may be other than cuboid presenting, for example, a flatter rectangular pack some 4 cm in height with side dimensions in the regions of 30 cm and 20 cm respectively.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Biochemistry (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Biophysics (AREA)
• Molecular Biology (AREA)
• Physics & Mathematics (AREA)
• Epidemiology (AREA)
• Analytical Chemistry (AREA)
• Animal Behavior & Ethology (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)
• Road Signs Or Road Markings (AREA)
• Investigating Or Analysing Biological Materials (AREA)
• Packages (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (8)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26290394

Family Applications (1)

Country Status (14)

Cited By (7)

Families Citing this family (16)

Citations (5)

Family Cites Families (9)

• 1987
  • 1987-02-20 MC MC87GB8700125D patent/MC1858A1/xx unknown
  • 1987-02-20 CA CA000530237A patent/CA1294832C/en not_active Expired - Lifetime
  • 1987-02-20 AT AT87901544T patent/ATE87829T1/de not_active IP Right Cessation
  • 1987-02-20 AU AU70363/87A patent/AU604013B2/en not_active Ceased
  • 1987-02-20 JP JP62501361A patent/JPH074409B2/ja not_active Expired - Lifetime
  • 1987-02-20 WO PCT/GB1987/000125 patent/WO1987004931A1/en not_active Ceased
  • 1987-02-20 BR BR8707600A patent/BR8707600A/pt not_active IP Right Cessation
  • 1987-02-20 DE DE8787901544T patent/DE3785345T2/de not_active Expired - Lifetime
  • 1987-02-20 US US07/235,897 patent/US4902478A/en not_active Expired - Lifetime
  • 1987-02-20 EP EP87901544A patent/EP0297098B1/en not_active Expired - Lifetime
  • 1987-02-22 IE IE44387A patent/IE59469B1/en not_active IP Right Cessation
• 1988
  • 1988-02-20 GB GB8819711A patent/GB2208436A/en active Granted
  • 1988-08-19 RU SU884356433A patent/RU1837892C/ru active
  • 1988-08-19 FI FI883846A patent/FI94929C/fi not_active IP Right Cessation

Patent Citations (5)

Also Published As

Similar Documents

Legal Events