SLIDE 1
The Bowie and Dick Type The Bowie and Dick Type Test Test Does size and penetration Does size and penetration really matter? really matter?
Presented by Presented by Terry McAuley Terry McAuley Sterilisation and Infection Control Sterilisation and Infection Control Consultant Consultant
SLIDE 2 Discuss the purpose of the Bowie Dick type test
Discuss the purpose of the Bowie Dick type test
Examine the applicable European Norms (EN) &
Examine the applicable European Norms (EN) & International Standards Organisation (ISO) International Standards Organisation (ISO) standards that refer to Bowie-Dick type tests standards that refer to Bowie-Dick type tests
Outline the basic requirements in the EN & ISO
Outline the basic requirements in the EN & ISO standards that can be used to evaluate claims of standards that can be used to evaluate claims of test conformance test conformance
Explain the correct method for performance,
Explain the correct method for performance, interpretation and documentation of the Bowie-Dick interpretation and documentation of the Bowie-Dick type test type test
SLIDE 3 It’s a matter of physical It’s a matter of physical chemistry….. chemistry…..
A Bowie-Dick is a physical test uses a
A Bowie-Dick is a physical test uses a chemical indicator to demonstrate that chemical indicator to demonstrate that steam penetration has been adequate by steam penetration has been adequate by showing a uniform colour change in the showing a uniform colour change in the indicator indicator
– In order for the indicator to change colour a In order for the indicator to change colour a chemical reaction must occur at certain chemical reaction must occur at certain temperatures in the presence of moisture temperatures in the presence of moisture – By default, a satisfactory result translates into an By default, a satisfactory result translates into an assumption that air removal was adequate assumption that air removal was adequate
SLIDE 4 Size matters…….. Size matters……..
Required for the test:
Required for the test:
– Huckaback towels (36” x 24” ) folded to give 8 thicknesses Huckaback towels (36” x 24” ) folded to give 8 thicknesses
25-29 were required to create a stack of the right height
25-29 were required to create a stack of the right height
– Two 12” strips of autoclave tape placed in the form of a Two 12” strips of autoclave tape placed in the form of a cross on a 10” x 8” sheet of unglazed paper cross on a 10” x 8” sheet of unglazed paper
These sheets could be inserted at various levels throughout
These sheets could be inserted at various levels throughout the stack, although one sheet in the centre of the pack was the stack, although one sheet in the centre of the pack was acceptable acceptable
– Huckaback towels in a 10”-11” high stack were then Huckaback towels in a 10”-11” high stack were then placed in a rectangular dressing casket, cardboard box or placed in a rectangular dressing casket, cardboard box or were wrapped in fabric were wrapped in fabric
– Bowie et al (1963) Bowie et al (1963)
SLIDE 5
SLIDE 6 In their own words…. In their own words….
“
“This test is essentially a test of steam This test is essentially a test of steam penetration, not of time-at-temperature” penetration, not of time-at-temperature”
“
“A satisfactory test will indicate rapid steam A satisfactory test will indicate rapid steam penetration, adequate air removal and penetration, adequate air removal and freedom from significant air leaks.” freedom from significant air leaks.”
“
“A uniform colour change may be obtained A uniform colour change may be obtained without adequate initial air removal if the without adequate initial air removal if the holding time is artificially extended” holding time is artificially extended”
– Beyond 3 ½ minutes@ 134 Beyond 3 ½ minutes@ 1340
0C
C
– Bowie et al (1963) Bowie et al (1963)
SLIDE 7 In their own words…. In their own words….
“
“In some sterilisers In some sterilisers (where steam is admitted during
(where steam is admitted during vacuum phases) vacuum phases) penetration will occur and the
penetration will occur and the load temperature will rise before the end of load temperature will rise before the end of the prevacuum period. In such sterilisers a the prevacuum period. In such sterilisers a satisfactory result indicates adequate steam satisfactory result indicates adequate steam penetration but does not necessarily confirm penetration but does not necessarily confirm a suitable degree of air tightness … a suitable degree of air tightness … ..therefore an air leakage test may be ..therefore an air leakage test may be needed in addition.” needed in addition.”
– Bowie et al (1963) Bowie et al (1963)
SLIDE 8 Change is inevitable…. Change is inevitable….
That was then…
That was then…
– Single deep vacuum Single deep vacuum phase +/- conditioning phase +/- conditioning – Majority of items Majority of items processed were porous processed were porous in nature in nature – Surgical instruments Surgical instruments mostly constructed of mostly constructed of metal metal – Very few multi-part or Very few multi-part or cannulated devices cannulated devices
This is now…
This is now…
– Superatmospheric, Superatmospheric, transatmospheric or transatmospheric or subatmospheric pulsing subatmospheric pulsing – Majority of items Majority of items processed are non- processed are non- porous porous – Surgical instruments Surgical instruments constructed of a variety constructed of a variety
– Large percentage of Large percentage of multi-part and long- multi-part and long- lumened devices lumened devices
SLIDE 9
Is the Bowie & Dick test Is the Bowie & Dick test still relevant? still relevant?
What do you think?
What do you think?
SLIDE 10 What do we need to What do we need to check for? check for?
Chamber integrity – to ensure no air
Chamber integrity – to ensure no air leakage is present at any stage of the leakage is present at any stage of the sterilisation cycle sterilisation cycle
Ability of the vacuum pump to eliminate air
Ability of the vacuum pump to eliminate air from the chamber and load from the chamber and load
Steam quality
Steam quality
SLIDE 11
Performance Testing of Performance Testing of Steam Sterilisers Steam Sterilisers
Air Leakage Test
Air Leakage Test
– Establishes that no air leakage will occur Establishes that no air leakage will occur during vacuum stages of the sterilisation during vacuum stages of the sterilisation cycle cycle
Leak rate tests are now an automatic
Leak rate tests are now an automatic test cycle on most modern sterilisers test cycle on most modern sterilisers
SLIDE 12 Performance Testing of Performance Testing of Steam Sterilisers Steam Sterilisers
Air detectors
Air detectors
– Commonly fitted to most modern Commonly fitted to most modern sterilisers sterilisers – Samples the conditions present in the Samples the conditions present in the steriliser chamber after the air removal steriliser chamber after the air removal stage and during steam admission, in stage and during steam admission, in every cycle every cycle – Is set to cause the cycle to abort if Is set to cause the cycle to abort if temperature differences ≥ 2 temperature differences ≥ 20
0 C are
C are detected detected
SLIDE 13
Performance Testing of Performance Testing of Steam Sterilisers Steam Sterilisers
Air removal and steam penetration
Air removal and steam penetration test test
– Establishes efficacy of vacuum system Establishes efficacy of vacuum system and can give an indication of steam and can give an indication of steam quality –i.e. presence of non-condensable quality –i.e. presence of non-condensable gases gases
Commercially available alternatives to
Commercially available alternatives to the original Bowie & Dick test are in the original Bowie & Dick test are in widespread use widespread use
SLIDE 14
What Standards are there What Standards are there that refer to B&D tests? that refer to B&D tests?
LOTS!!!!!! LOTS!!!!!!
SLIDE 15 Which Standards? Which Standards?
EN 867-3:1997
EN 867-3:1997
EN 867-4:2001
EN 867-4:2001
ISO 15882:2003
ISO 15882:2003
EN 285 / prEN285 (2006)
EN 285 / prEN285 (2006)
prEN ISO/FDIS 17665-1
prEN ISO/FDIS 17665-1
ISO/CD 17665-2
ISO/CD 17665-2
ISO 11140 Parts 1-5
ISO 11140 Parts 1-5
Just to name the most relevant few………….
SLIDE 16 ISO 11140 ISO 11140 Sterilisation of Health Sterilisation of Health Care Products – Chemical Care Products – Chemical indicators indicators
All of these documents are currently under
All of these documents are currently under review….. review…..
– ISO 11140 -3 2000 ISO 11140 -3 2000– Part 3 Class 2 indicators for – Part 3 Class 2 indicators for steam penetration test steam penetration test sheets sheets – ISO 11140 -4 2001 ISO 11140 -4 2001– Part 4 Class 2 indicators – Part 4 Class 2 indicators for steam penetration test for steam penetration test packs packs – ISO 11140 -5 2000 ISO 11140 -5 2000– Part 5 Class 2 indicators for – Part 5 Class 2 indicators for air removal test sheets and packs air removal test sheets and packs
SLIDE 17 ISO/DIS 11140-3
ISO/DIS 11140-3
– Specifications only for test indicator Specifications only for test indicator sheets that are to be used in conjunction sheets that are to be used in conjunction with a standard test pack as described in with a standard test pack as described in EN 285 EN 285
– (Equivalent to original BD pack) (Equivalent to original BD pack)
– This Standard specifies the performance This Standard specifies the performance
- f the indicator, but not that of the test
- f the indicator, but not that of the test
pack itself pack itself
SLIDE 18
SLIDE 19 ISO/DIS 11140-4
ISO/DIS 11140-4
– Specifies the performance of the indicator Specifies the performance of the indicator system in combination with the test load with system in combination with the test load with which it is intended to be used which it is intended to be used
May be single or multi-use with a new indicator each
May be single or multi-use with a new indicator each time of use time of use
– Intended to indicate that steam penetration has Intended to indicate that steam penetration has been inadequate in the case of a number of been inadequate in the case of a number of different causes for fault cycles different causes for fault cycles – Does not include test methods to establish the Does not include test methods to establish the suitability of the indicators for use in sterilisers suitability of the indicators for use in sterilisers that that do not do not use a vacuum stage for air removal use a vacuum stage for air removal
SLIDE 20
SLIDE 21 ISO/DIS 11140-5
ISO/DIS 11140-5
– Specifies the requirements for an indicator and Specifies the requirements for an indicator and alternative test system used to evaluate the alternative test system used to evaluate the effectiveness of air removal during the effectiveness of air removal during the prevacuum phase of prevacuum steam prevacuum phase of prevacuum steam sterilisation cycles or during the pulsing stage of sterilisation cycles or during the pulsing stage of positive pulsing cycles positive pulsing cycles – Failure of the test could be due to retention of Failure of the test could be due to retention of air, an air leak or non-condensable gases during air, an air leak or non-condensable gases during the air removal stage the air removal stage
SLIDE 22 Summary of the Summary of the differences differences
(ISO 15882) (ISO 15882)
7kg pack 7kg pack 7kg pack 4kg pack
SLIDE 23 Fail condition per 11140-5 (inadequate air removal) T0 in chamber drain Fail condition per 11140-3
(Original Bowie & Dick result)
Fail conditions per 11140-4
(Range of Causes)
ISO 15882, Annex A
SLIDE 24 Which test is right for my Which test is right for my steriliser? steriliser?
What air removal system does your steriliser
What air removal system does your steriliser have? have? – Subatmospheric Subatmospheric
– Pulses occur all below atmospheric conditions Pulses occur all below atmospheric conditions
– Transatmospheric Transatmospheric
– Pulses occur above and below atmospheric Pulses occur above and below atmospheric conditions conditions
– Superatmospheric Superatmospheric
– Initial vacuum pulses followed by Initial vacuum pulses followed by superatmospheric pulses superatmospheric pulses
Check both the steriliser and BD test
Check both the steriliser and BD test manufacturer’s recommendations manufacturer’s recommendations
SLIDE 25 What are you using the What are you using the Bowie and Dick test to do? Bowie and Dick test to do?
Check only for adequate air removal?
Check only for adequate air removal?
– Select a test compliant with ISO 11140-5 Select a test compliant with ISO 11140-5
Check for both air removal and steam
Check for both air removal and steam penetration? penetration?
– Select a test sheet compliant with ISO11140-3 Select a test sheet compliant with ISO11140-3
Check for both air removal, steam
Check for both air removal, steam penetration and possible failures due to penetration and possible failures due to
– Select a test compliant with ISO11140-4 Select a test compliant with ISO11140-4
SLIDE 26
What to look for in a What to look for in a test… test…
Conformance to the applicable EN or
Conformance to the applicable EN or ISO Standards ISO Standards
– Independent certification of conformance Independent certification of conformance in preference to self certification in preference to self certification – Clear instructions on how to store, Clear instructions on how to store, handle, use and interpret the test handle, use and interpret the test – Information on the reliability in Information on the reliability in maintaining end point change maintaining end point change
SLIDE 27 What to look for in a test.. What to look for in a test..
The indicator sheet
The indicator sheet
– Reagent must cover ≥ 30% of the sheet with no Reagent must cover ≥ 30% of the sheet with no more than 20mm gap between areas of reagent more than 20mm gap between areas of reagent – The pattern must enable clear interpretation of The pattern must enable clear interpretation of the colour change the colour change – The edges must be able to be compared with The edges must be able to be compared with the centre and be of A4 size the centre and be of A4 size (ISO 11140-3 only)
(ISO 11140-3 only)
– The dye must be non-toxic and non-transferable The dye must be non-toxic and non-transferable – The indicator itself or the pre-assembled pack The indicator itself or the pre-assembled pack must allow writing to be made on it must allow writing to be made on it
SLIDE 28
Clear colour change Clear colour change
Unprocessed Processed (Pass)
SLIDE 29
Edges can be compared Edges can be compared to the centre to the centre
Processed (Examples of Failures)
SLIDE 30
Writing can be made on Writing can be made on the pack or the test sheet the pack or the test sheet
SLIDE 31 How to perform the test How to perform the test
Empty chamber except for chamber
Empty chamber except for chamber furniture and the test itself furniture and the test itself
Locate the test in the geometric centre of
Locate the test in the geometric centre of the horizontal plane of the usable chamber the horizontal plane of the usable chamber space between 100-200mm from the space between 100-200mm from the chamber base (EN 285) chamber base (EN 285)
– This may or may not be over the chamber drain This may or may not be over the chamber drain
SLIDE 32
This is NOT how to use a This is NOT how to use a BD type test ! BD type test !
SLIDE 33
How to perform the test How to perform the test
The sterilising stage of the cycle must
The sterilising stage of the cycle must be no longer than 3 ½ minutes be no longer than 3 ½ minutes
– Many sterilisers now incorporate a pre-set Many sterilisers now incorporate a pre-set air removal and steam penetration test air removal and steam penetration test cycle cycle – Drying times should not be extended Drying times should not be extended
SLIDE 34 How to interpret the How to interpret the result result
Standard Procedure to
Standard Procedure to be followed be followed
All staff trained to
All staff trained to interpret the result interpret the result according to according to manufacturer’s manufacturer’s instructions instructions
Flat surface and clear
Flat surface and clear
- verhead lighting
- verhead lighting
Compare edges to
Compare edges to centre centre
SLIDE 35
Record Keeping Record Keeping
There is no specified guidance with
There is no specified guidance with respect to the length of time to keep a respect to the length of time to keep a chemical indicator result, even a BD chemical indicator result, even a BD indicator indicator
– ISO 15882 states that users may record ISO 15882 states that users may record the outcome or result of the indicator, or the outcome or result of the indicator, or choose to retain it for varying periods of choose to retain it for varying periods of time according to local requirements time according to local requirements
SLIDE 36
In conclusion… In conclusion…
“
“We hope that others will use it, We hope that others will use it, perhaps in conjunction with more perhaps in conjunction with more refined methods, to examine refined methods, to examine sterilisers…and in doing so….they will sterilisers…and in doing so….they will collect much needed information about collect much needed information about the current status of sterilisers…” the current status of sterilisers…”
– Bowie et al (1963) Bowie et al (1963)
SLIDE 37 References and Further References and Further Reading Reading
Bowie, J. H., Kelsey, J. C., Thompson, G. R. (1963)
Bowie, J. H., Kelsey, J. C., Thompson, G. R. (1963) The Bowie and Dick Autoclave Tape Test. The Bowie and Dick Autoclave Tape Test. The The Lancet, pp586-587 Lancet, pp586-587
Bowie, J. (1984)
Bowie, J. (1984) Dr John Bowie on the Bowie and Dr John Bowie on the Bowie and Dick test. Dick test. Journal HSPD March/April Vol 2 No.2 pp Journal HSPD March/April Vol 2 No.2 pp 26-28 26-28
Mayworm, D. (1984)
Mayworm, D. (1984) The Bowie-Dick type test…Are The Bowie-Dick type test…Are there alternative ways? there alternative ways? Journal HSPD Journal HSPD Vol 2, No. 2 Vol 2, No. 2 pp 31-34 pp 31-34
Ryan, P. (1984)
Ryan, P. (1984) The Bowie-Dick type test…The The Bowie-Dick type test…The discrepancies between theory and practice. discrepancies between theory and practice. Journal Journal HSPD March/April Vol 2, No.2. pp20-24 HSPD March/April Vol 2, No.2. pp20-24
SLIDE 38 References and Further References and Further Reading Reading
EN 285
EN 285 Large steam sterilisers Large steam sterilisers
EN 867-3:1997
EN 867-3:1997 Non-biological systems for use in Non-biological systems for use in
- sterilisers. Part 3: Specification for Class B
- sterilisers. Part 3: Specification for Class B
indicators for use in the Bowie and Dick test. indicators for use in the Bowie and Dick test.
EN 867-4:2001
EN 867-4:2001 Non-biological systems for use in Non-biological systems for use in
- sterilisers. Part 4 : Specification for indicators as an
- sterilisers. Part 4 : Specification for indicators as an
alternative to the Bowie and Dick test for detection alternative to the Bowie and Dick test for detection
- f steam penetration.
- f steam penetration.
EN
EN 867-5:2001 867-5:2001 Non-biological systems for use in Non-biological systems for use in
- sterilisers. Part 5: Specification for indicator
- sterilisers. Part 5: Specification for indicator
systems and process challenge devices for use in systems and process challenge devices for use in performance testing for small steam sterilisers Type performance testing for small steam sterilisers Type B and Type S. B and Type S.
SLIDE 39 References and Further References and Further Reading Reading
Borchers, U. & Mielke, M. (2004)
Borchers, U. & Mielke, M. (2004) How How material, length, wall thickness and material, length, wall thickness and diameter of hollow devices affect the diameter of hollow devices affect the inactivation of biological indicators when inactivation of biological indicators when subjected to moist heat treatment. subjected to moist heat treatment. Zentral Zentral Sterilisation Vol. 12 (5) pp314-322 Sterilisation Vol. 12 (5) pp314-322
Eifler, P. (2004)
Eifler, P. (2004) Is the steam OK? The air Is the steam OK? The air detector knows the answer. detector knows the answer. Zentral Zentral Sterilisation Vol. 12 (4) pp279-281 Sterilisation Vol. 12 (4) pp279-281
SLIDE 40 References and Further References and Further Reading Reading
ISO 11140 -1 2005
ISO 11140 -1 2005 Sterilisation of Health Care Sterilisation of Health Care Products – Chemical indicators – Part 1 General Products – Chemical indicators – Part 1 General Requirements Requirements
– ISO 11140 -3 2000 ISO 11140 -3 2000– Sterilisation of Health Care Products – – Sterilisation of Health Care Products – Chemical indicators – Part 3 Class 2 indicators for steam Chemical indicators – Part 3 Class 2 indicators for steam penetration test penetration test sheets sheets – ISO 11140 -4 2001 ISO 11140 -4 2001– Sterilisation of Health Care Products – – Sterilisation of Health Care Products – Chemical indicators – Part 4 Class 2 indicators for steam Chemical indicators – Part 4 Class 2 indicators for steam penetration test penetration test packs packs – ISO 11140 -5 2000 ISO 11140 -5 2000– Sterilisation of Health Care Products – – Sterilisation of Health Care Products – Chemical indicators – Part 5 Class 2 indicators for Chemical indicators – Part 5 Class 2 indicators for air air removal test sheets and packs removal test sheets and packs
SLIDE 41 References and Further References and Further Reading Reading
ISO 11139 (draft 2005)
ISO 11139 (draft 2005) Sterilisation of Sterilisation of health care products – Vocabulary 2 health care products – Vocabulary 2nd
nd
edition edition
ISO 15882:2003
ISO 15882:2003 Sterilisation of Health Care Sterilisation of Health Care Products – Chemical indicators – Guidance Products – Chemical indicators – Guidance for selection, use and interpretation of for selection, use and interpretation of results results
ISO 15882 (draft 2005)
ISO 15882 (draft 2005) Sterilisation of Sterilisation of health care products – Chemical indicators – health care products – Chemical indicators – Guidance for the selection, use and Guidance for the selection, use and interpretation of results. interpretation of results.
SLIDE 42 References and Further References and Further Reading Reading
ISO/DIS 17665-1 ISO/DIS 17665-1 Sterilisation of health Sterilisation of health care products –Moist Heat – Part 1 care products –Moist Heat – Part 1 Requirements for the development, Requirements for the development, validation and routine control of a validation and routine control of a sterilisation process for medical devices sterilisation process for medical devices
ISO/CD 17665-2 ISO/CD 17665-2 Sterilisation of health care Sterilisation of health care products – Moist Heat – Part 2 Guidance products – Moist Heat – Part 2 Guidance
- n the application of ISO 17665-1.
- n the application of ISO 17665-1.
AS 1410 – 2003 AS 1410 – 2003 Sterilisers-Steam- Sterilisers-Steam- Prevacuum Prevacuum
