Steam penetration Josephus Paulus Clemens Maria van Doornmalen Gomez Hoyos March 2012 Dutch Norm Committee and Dutch delegate in EN TC 102 WG 2 Testing EN TC WG 3 Requirements EN TC WG 5 Small steam sterilizers EN TC WG 6 Gas sterilizers EN TC WG 7Biological and chemical indicators ISO TC 198 WG 1 Industrial ethylene oxide sterilization ISO TC 198 WG 3 Moist heat sterilization ISO TC 198 WG 4 Biological indicators ISO TC 198 WG 6 Chemical indicators ISO TC 198 WG 13 Washer-disinfectors
Outline Standards Strategy Steam penetration tests Chemical Indicator update Standards are necessary confidential
Medical Research Council (1959, MRC) Perkins MRC Time Temp Time Temp [min] [ C] [min] [ C] 2 132 3 134 8 125 10 127 12 121 15 121 Rational MRC: Steam quality
Criteria in norms Pressure Temperature Phase I Phase 1: Conditioning Phase 2: Sterilization Time Phase 3: Drying and pressure equalization Specify conditions in sterilization phase Specify end result Specify NOT phase 1 and before
ISO 11140 Part 1: General requirements Clause 4 Classification 4.2 Class 1: process indicators 4.3 Class 2: indicators for use in specific tests 4.4 Class 3: single variable indicators 4.5 Class 4: multi-variable indicators 4.6 Class 5: integrating indicators 4.7 Class 6: emulating indicators
Chemical indicators norm ISO 11140 Part 1: General requirements Part 2: Test equipment and methods Part 3: Class 2 indicators for steam penetration test sheets Part 4: Class 2 indicators for steam penetration test packs Part 5: Class 2 indicators for air removal test sheets and packs Part 6: possibly Process Challenge Devices for steam sterilization (New work item ISO/TC 198/WG 6)
The original "Huckaback Towel Pack" according to Dr. J. H. Bowie and Mr. J. Dick THE BOWIE AND DICK AUTOCLAVE TAPE TEST, The Lancet, (1963), S.586 7
Steam sterilization process Steam injection Start of sterilization phase Steam sterilization conditio Pressur re Time Suction
Steam penetration and condensation Condensation front Gases sucked out, textile stays wet Good penetration Time
Insufficient deep vacuum Condense front will not disappear
Effect NCG s Steam Injection (Steam with NCG s) O 2, N 2, CO 2, H 2 O Steam injection, pressure increasing Condensation of water
Helix Examples Helix schematically Tube Receptacle Lumen
Penetration in lumen Pressure Time Length = L Length = ½L Closed end
Examples hollow instruments Lumen
Helix Examples Helix schematically Tube Receptacle Lumen
Configuration of instruments Relatively difficult to penetrate Relatively easy to penetrate
Swirl Swirl Well known and described phenomena Axial dispersion and flow phenomena in helically coiled tubular reactors for flow analysis and chromatography, R. Tijssen, Analytica Chimica Acta, 114, 1980, 71-89:
Wall thickness Wall thickness More heat capacity (e.g., more condensation) Heat transfer Research ongoing
Dimensions of tube Radius Length r Research ongoing
Norms Institutes International Organization for Standardization (ISO) ISO standards CEN EN standards Country Norm Institute Germa ny (DIN) UK (BSI) The Netherlands (NEN) France (Afnor) USA (AAMI) South Africa (SABS) Colombia (ICONTE C) Brazil (ABNT ) Japan (JISC ) China (SAC ) Australia (SA)
Sequence of standards A higher organization supersedes regional or country standards If a topic is address on a higher level the lower level must stop work(ing) on the that topic ISO standard DIN ISO 12345 European standard Country standard DIN EN 12345 DIN 12345
Current situation in norm committees penetration tests Current standard EN 867 part 5: Non-biological systems for use in sterilizers - Part 5: Specification for indicator systems and process challenge devices for use in performance testing for small sterilizers Type B and Type S 4.2 Process challenge device for porous load 4.3 Indicator systems for use in the porous load process challenge device 4.4 Alternative indicators equivalent to the porous load process challenge device test 4.5 Process challenge devices for hollow instrument loads (hollow load process challenge device) Parts 1 to 4 are already in the ISO 11140 part 1 to 4
EN 13060 Small steam sterilizers Draft version: Device will go in informative annex possibly disappearal
EN 285 Sterilization Steam sterilizers Large sterilizers (includes Amendment A2:2009) 8.2.5 Hollow load test When the sterilizer is tested in accordance with Clause 15, the indicator system shall have reached its endpoint as described by the manufacturer of the indicator system. 15.2.2 Indicator system in accordance with EN 867-5 for the hollow load test.
EN 285 penetration test 8.1 Steam penetration 8.1.1 When tested in accordance with 16.1, the result shall be in accordance with 8.2.1.2. 8.1.2 When tested in accordance with 16.2, the result shall be in accordance with 8.2.1.3. 8.1.3 When tested in accordance with Clause 17, the result shall be in accordance with 8.2.2. 8.1.4 When tested in accordance with Clause 15, the result shall be in accordance with 8.2.5.
EN 285 penetration test 8.1.3 17 Bowie and Dick test 8.1.3 When tested in accordance with Clause 17, the result shall be in accordance with 8.2.2. NOTE 2: In healthcare there has been an increase in the use of instruments with long lumens. For some of these instruments the air removal efficacy identified by the tests based on textile loads may be inadequate. These tests have their origin in the steam penetration test using a textile pack1). It was designed to establish that at the commencement of the plateau period, air removal had been sufficient to The hollow load test complements these tests and should be achieve a vapour temperature throughout a textile load equivalent to the regarded as an addition to, and not as a replacement to them. vapour pressure of the steam in the sterilizer chamber. The hollow load test complements these tests and should be regarded as an addition to, and not as a replacement to them. A successful hollow load test indicates adequate air removal and even steam penetration into a process challenge device. A failure of any steam penetration test can be caused by an inefficient air removal stage, the presence of an air leak into the sterilizer chamber, and/or the presence of non-condensable gases in the steam supply."
Chemical indicators norm ISO 11140 Part 1: General requirements Part 2: Test equipment and methods Part 3: Class 2 indicators for steam penetration test sheets Part 4: Class 2 indicators for steam penetration test packs Part 5: Class 2 indicators for air removal test sheets and packs Part 6: possibly Process Challenge Devices for steam sterilization (New work item ISO/TC 198/WG 6)
Current situation Doubts in: EN TC WG 5 revision EN 13060 Put the devices in informative annex Will make remark that the device does not represent actual loads ISO TC 198 WG 6 EN 867 part 5 revision Started Round Robin testing in 2009 4 labs involved, standardized protocol, device, indicator, conditioning, sterilizers, processes No consistency found in results Next meeting May 2011 Scientific approach no relation with actual loads
Orientation study Orientation study to find out if commercial available Process Challenge Device fulfil the claims made and the ISO 11140 part 3 or 4. Method used is: compare available test in with equipment fulfilling the norms According to specified test processes in the ISO 11140 part 4 This is not a detailed study
Claims used Penetration test material ETS (3M, Germany) Claim: comply with the ISO 11140 part 4 (full claim see last slides) GKE Compact PCD Bowie-Dick Simulation Test Claim: Air removal and steam penetration test validated according the test method of EN ISO 11140 part 4 + 1 Class 2 with reference to the 7 kg test pack in EN 285 and hollow test exceeding the requirements of EN-867-5 Interster ISP control Helix Test system Claim: EN 867-5 EN-ISO 11140 (class 6 indicators)
Test equipment and conditions Test sterilizer: Lautenschläger type 3119 4 STE Programs used are programmed as described in the ISO 11140-4:2007(E)Sterilization of health care products Chemical indicators Part 4: Class 2 indicators as an alternative to the Bowie and Dick-type test for detection of steam penetration Plateau period 3,5 minutes in all processes Before testing sterilize was warmed up before testing
B.1 Cycle 1: Air removal by sub-atmospheric pulsing
B.2 Cycle 2: Air removal by trans-atmospheric pulsing
B.3 Cycle 3: Air removal by super-atmospheric pulsing
Positions of PCDs during testing
Experimental method Processes used out of the ISO 11140 part 4 : B.1 Cycle 1: Air removal by sub-atmospheric pulsing B.2 Cycle 2: Air removal by trans-atmospheric pulsing B.3 Cycle 3: Air removal by super-atmospheric pulsing Cycles: Pass See back up slides for details on standard processes Bad vacuum Air injection ETSses are used to verify cycles
Interster ISP control Helix Test system Used in experiment: Art.No. 33002030 steam Dark 134 C 3,5 min / 121 C 15 min
Results Interster ISP control Helix Test system Remarks: Colour changes of indicators are seen after process, but look similar for pass and fail None of the processed indicators reaches reference colour (Added) value of product not understood (not for small or large sterilizers)
Results GKE Compact PCD Bowie-Dick Simulation Test
Remarks: Results GKE Compact PCD Bowie-Dick Simulation Test Fail B3 cycle with air injection resulted in a pass This introduces a false sense of safety. (Air Leakage test only detects sub atmospheric leaks. Control valves are controlled by compressed (typically 6 bar). Leaks in the valves are shown with air injection tests) Fail B1 cycle with air injection restated in a pass (tested up to 3 bars) May introduce a false sense of safety (see above). It looks like the PCD Bowie and Dick test (ref 211-150 ENS) do not comply with 2 out 3 tests to comply with the ISO 11140 part 4
ICEN/CENELEC internal regulations define a standard Nature is NOT democratic and Document, established by consensus and approved by a recognized does body NOT that provides, do for consensus common an repeated use, rules guidelines Human can or define characteristics a meter for but activities or their results, human aimed cannot at the decide achievement when organisms of the optimum die degree of order in a given order. We need evidence confidential
Basis Standards are necessary. Standards should be evidence based Standards are not always evidenced based Not data available Not possible Other reasons, confidential
olutions and products Ethical Safe Evidence based where possible Prefer evidence based standards Perform studies to bring evidence to the public domain End users Standard committees confidential
We do not believe in the saying: Better do something than nothing if it introduces doubts if safety could be jeopardized we do not want to introduce a false sense of safety confidential
Members National committees and workgroups End users, manufacturers, governmental institutions, research centers European committees Delegates from European countries ISO committees Delgates from member countries Composition of committees should be a reflection form users confidential
Steam penetration Hollow A Hollow A, hollow load A, helix, PCDs Type in Google images: helix devices steam penetration confidential
ISO 11140 part 6 ISO 11140 part 6 is intended to replace EN 867- Clause defines the hollow load 4.5 Process challenge devices for hollow instrument loads (hollow load process challenge device) With Hollow load, hollow A and helix is meant the same: confidential
Discussion Since introduction helix systems a discussion First half 2009:TC 198 WG 4 Chemical indicators perform a Round Robin test 3 revisions of protocol: no data in public domain Neuss lab performed their own study confidential
Some helix testing in Neuss lab Helix PCD device as in Round Robin Study Protocol as in Round Robin Study Process as I in Round Robin Study Chemical indicators as in Round Robin Study Our 2 test sterilizers (11 l and 342 l) confidential
Process Pressure CP Come-up 4 pulses : CP vac = 300, 320, 350, 370, 400 mbar 3 pulses : CP steam = 950mbar Come-up : CP = 3100 mbar Target P/ t: 400mbar/min CP Steam CP vac Time confidential
Results I Chemical Indicator Colour Development B1 400mbar/min - ST3-RM 11 litre 300-950mbar 320-950mbar 350-950mbar 400-950mbar 3949 3948 3947 3946 3940 3939 3938 3937 3936 4029 4028 4027 4026 4025 4024 4022 4021 4020 4019 4011 4010 4009 4008 4007 3964 3962 3958 3956 3954 3952 4002 3971 3970 3969 3968 3967 3965 3963 3961 3957 3955 3953 3950 3999 3998 3997 3996 3995 3994 3993 3992 3991 3989 3988 3987 0% 50% 100% 0% 50% 100% 0% 50% 100% 0% 50% 100% confidential
Results II Chemical Indicator Colour Development B1 400mbar/min ST1-4 342 litre 300-950mbar 320-950mbar 350-950mbar 370-950mbar 10113 10112 10111 10110 10069 10068 10067 10066 10065 10064 10063 10059 10058 10054 10109 10108 10107 10106 10105 10102 10101 10100 10099 10098 10097 10096 10091 10090 10089 10088 10087 10086 10082 10079 10078 10077 10076 10075 10074 10073 10072 10071 10070 10056 10055 10127 10126 10125 10124 10123 10122 10121 10120 10119 10118 10117 10116 10081 0% 50% 100% 0% 50% 100% 0% 50% 100% 0% 50% 100% confidential
Results interpretation I confidential
Results interpretation II Differences between small and large test sterilizer Round Robin does not classfy the PCD (yet?) Original Standard Textile pack in process (VCP = 300 mbar) ISO 11140-4, max 2 K In process with VCP = 300 mbar: 75,4, 81.4 and 88.7 K confidential
Conclusion Hollow, hollow A and/or helix PCDs introduce a false sense of safety should not be used in standards should not be used for steam penetration should not be used Batch Monitoring systems standard committees should look at these results E.g. proposal for Medical Device Simulator (NWI: DIN 58921) (publication in preparation) confidential
Alternatives for penetration tests and BMS Test meeting requirements in ISO 11140 part 4 Large sterilizers ETS Small sterilizers 1300 and 1301 (and soon 1233) BMS No standards, research ongoing confidential
ISO 11140 part 1, class 4, 5 and 6 CIs Discussions on class 5 and 6 in committees and field Decided to study 6 commercially available class 6 CI for steam sterilization confidential
Protocol based on ISO 11140 part 1 Square wave 134 C Vary the exposure time: 0, 1, 15, 30, 45, 60,..., 300, 330, 360, 390, 420, and, 900 s X-rite 528 Spectrodensitometer to measure color Measured CI and reference ink on indicator Indicator surface Reference color surface Tested against there own Stated Values and accuracies confidential
Criteria class 6 CIs 3M 2010. All Rights Resered. confidential
Some results: example color changes CI 330, 360, 390, 420, and, 900 s 0, 1,15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180 s 195, 210, 225, 240, 255, 270, 285, 300 s Obviously human eye not objective Therefore measurements confidential
Some more results Difficult if possible at all to see the results What is a pass? When is it a pass? confidential
Method measuring objective L*a*b method Ink measured Reference color measured Result ink result reference. Pass results equals 0 Fail result does not equal 0 confidential
Measured results Non of the results go to 0 Almost all turn over too early In some case Cis color difference is hardly seeable If not seeable with measurements not seeable with human eye confidential
Conclusions Standards are necessary Current helix device does not meet claims Current color change based (class 6) Cis do not meet claims Do not use helix shaped devices Suggestion translate the published articles on helix shaped devices in local language Become member of (national) norm committees confidential