Process Monitoring of Steam Steriliza3on Regula3ons & Use of Chemical and Biological Indicators

Transcription

1 Process Monitoring of Steam Steriliza3on Regula3ons & Use of Chemical and Biological Indicators Richard Bancro,, B.Sc (Hons) Development and Technical Service Director Albert Browne Ltd A subsidiary of STERIS CorporaFon Registered Authorising Engineer (DecontaminaFon), UK Convenor, ISO TC 198 WG 6 Member, AAMI Standards Board, USA Albert Browne Ltd 2012

2 STERILIZATION STANDARDS Albert Browne Ltd 2012

3 LEGAL FRAMEWORK

4 Standards Hierarchy AU TherapeuFc Goods Act Europe Medical Device DirecFve USA 21 CFR AU Medical Device Standards Order Europe HarmonisaFon USA FDA RecogniFon AU Standards Europe Standards USA Standards AU Guidance Documents Europe Guidance Documents USA Guidance Documents AU Local Procedures Europe Local Procedures USA Local Procedures

5 Acts, DirecFves, Codes Legal Instruments Must be complied with Non- specific and a number of opfons to meet compliance SubjecFve

6 Medical Device Standards Order - AU Used to demonstrate compliance with the EssenFal Principles or Conformity Assessment Procedures Non- mandatory, but best method to demonstrate compliance If used, compliance with the EssenFal Principles or Conformity Assessment Procedures that they have been deemed to address is assumed.

7 Harmonised EN Standards The term harmonised is not as it seems! Term harmonised means harmonised to a European DirecFve Not all EN standards are harmonised Harmonised - A table exists that cross references clauses of the standard with clauses of the EssenFal Requirements of the direcfve Found in Annex ZA

8 Annex ZA Compliance with clauses of a standard (in Table ZA) confers, within the limits of the scope of this standard, a presump3on of conformity with the corresponding EssenFal Requirements of that DirecFve

9 Annex ZA

10 FDA RecogniFon - US FDA publish Recognized Consensus Standards FDA recognifon allows manufacturers to use standards as a route to clearance Clearance in US is 510(k)

11 Standards Standards are much more prescripfve than DirecFves, Acts or Codes If a product claims conformity to a Standard, it must comply with every requirement in that Standard

12 STANDARDS DEVELOPMENT

13 How a Standard is Born Similar process for CEN and ISO Starts with a New Work Item Proposal (NWIP) This is in reality a dra, or outline standard This must be submided by a NaFonal Standards OrganisaFon (NSO), for example, Bsi or UNI, to CEN or ISO Balloted by applicable NSOs

14 ParFcipaFon Standards should be wriden by knowledgeable people RepresentaFon from users, regulators and manufacturers ParFcipaFon at EU or ISO level is representafon by country ParFcipants must represent views of their nafon UNI has representafon on many standards commidees

15 CEN Weighted VoFng 27 Countries of EU, plus EFTA VoFng weighted by size of country (pop) 29 votes for UK 3 votes for Iceland Proposal shall be adopted if % or more of the weighted votes cast are in favour AbstenFons not counted

16 CEN Weighted VoFng 29 votes each: DE, FR, GB, IT 27 votes each: ES, PL 14 votes each: RO 13 votes each: NL 12 votes each: BE,CZ, GR, HU, PT 10 votes each: AT, CH, SE, BG 7 votes each: DK, FI, IE, LT, NO, SK 4 votes each: CY, EE, LV, LU, SI 3 votes each: IS, MT

17 ISO 160 ISO Countries 1 country 1 vote USA has 1 vote United Kingdom has 1 vote

18 Standards Development Timelines Very slow! Typically 3 years; it is then revised again! pren/dis ballot period is 5 months

19 EN Standards EN documents have to be implemented into every EU member state (currently 27 countries) They must be implemented unaltered, so no nafonal deviafons are permided Any conflicfng nafonal standard has to be withdrawn

20 EN RaFfied Text EN standards are developed and ulfmately approved as RaFfied Texts These texts are what must be nafonally implemented Only when nafonally implemented are they legally significant E.g. UK adopfon as BS EN XXXX

21 ISO Standards There is no requirement to adopt an ISO standard They can be nafonally modified

22 Vienna Agreement Agreement on technical cooperafon between CEN and ISO of 1991 (Vienna Agreement), revised in 2001

23 ISO as EN An ISO standard can be adopted as an EN standard It is then labelled as an EN ISO XXXX As an EN it is subject to all the usual EN standard requirements NaFonal implementafon No nafonal changes permided

24 Standards EN ISO series Biological Indicators EN ISO series Chemical Indicators

25 EN ISO EN ISO was first published as an ISO standard in 1994, revised 2006 It specifies the requirements for the labelling and performance of biological indicators Subsequent parts of the standard give performance requirements of biological indicators for specific sterilizafon methods e.g. steam, ethylene oxide

26 ISO Developments ISO WD TS Method for validafon of a biological indicator period ISO Biological indicators for hydrogen peroxide vapour sterilizafon processes

27 EN ISO EN ISO was first published as an ISO standard in 1995, revised 2005 It specifies the requirements for the labelling and performance of chemical indicators Subsequent parts of the standard give performance requirements for Bowie Dick type indicators

28 Bowie Dick Standards EN ISO Specifies requirements for A4 Bowie Dick test sheet EN ISO Specifies requirements for alternafve Bowie Dick tests - European ISO Specifies requirements for test sheet and alternafve BD test - USA

29 ISO Developments Part 1 SystemaFc review Part 6 Class 2 indicators and process challenge devices for use in performance tesfng of steam sterilizers

30 SterilizaFon Guidance ISO Biological Indicator Guidance ISO Chemical Indicator Guidance

31 EN ISO EN ISO was first published as an ISO standard in 2000 It gives guidance on the selecfon, use and interpretafon of results of biological indicators when used to develop, validate and monitor sterilizafon processes

32 EN ISO EN ISO was first published as an ISO standard in 2003 It gives guidance for users on the selecfon, use and interpretafon of results of chemical indicators

33 WHAT IS PROCESS MONITORING?

34 Pack Monitoring VerificaFon that all parts of the load achieve sterilizafon condifons At validafon Basis of thermometric validafon Every pack Ensures sterilizafon condifons

35 Sterilizer Monitoring VerificaFon of air removal The acfon of removing air and replacing with steam EssenFal if the load is porous or can entrap air UFlises dynamic air removal (as opposed to passive air removal) Requires use of a Bowie Dick Test at commencement of day

36 Sterility Assurance The world can be divided into two groups- European approach US approach

37 European Approach Based on concept of parametric release- declarafon that product is sterile, based on records demonstrafng that the process parameters were delivered within specified tolerances [ISO/TS 11139] Chemical indicators are an intrinsic part of this process Process indicators Bowie Dick tests In- pack indicators

38 US Approach Based on biological monitoring of loads Chemical indicators used to support results from biological indicators Process indicators Bowie Dick tests In- pack indicators

39 WHY DO WE NEED PROCESS MONITORING?

40 Defini3on of Sterility There is general world wide agreement that terminally sterilized products should have a probability of less than 1 in 1,000,000 of having a surviving organism* have a sterility assurance level (SAL) of 10-6 *As per the definifon EN556

41 Overkill Method of Sterility Assurance Based on basic assumpfons Assumes 1,000,000 micro organisms on load Assumes lower resistance of populafon compared to reference organism (G. stearothermophilus) Many biological indicators (for steam) have 10 5 (and not 10 6 ) spores NOTE - 100,000 is 10% of 1,000,000!

42 First Minute of Cycle at 134 C No. of Micro- organisms Assumed bioburden of 10 6 micro- organisms Mins.

43 Second Minute of Cycle at 134 C No. of Micro- organisms Bioburden of 10 6 micro- organisms Mins. SAL 10-6

44 Safety Time or Overkill No. of Micro- organisms Assumed bioburden of 10 6 micro- organisms Mins. SAL 10-6 Plus 1 min. extra safety 3me

45 CriFcal Parameters SterilizaFon processes have crifcal parameters which must be adained if the process is to be successful For steam sterilizafon, the crifcal parameters are Time, Steam and Temperature It is these parameters which must be monitored for parametric release

46 HOW DO WE MONITOR THE STEAM STERILIZATION PROCESS?

47 Process Monitors Physical Chamber (drain) temperature Chamber pressure Biological Within challenge pack Chemical Bowie Dick Test In- pack indicators

48 Physical Monitors Monitor Fme, temperature Temperature not measured in load Steam not directly detected

49 Biological Do not monitor enfre cycle Not directly placed within load

50 Chemical Used to assess steam penetrafon capability of sterilizer Used to monitor sterilizafon condifons in sterilizer chamber or from within the load Used in combinafon with physical parameter monitoring and biological indicators as part of a total system of sterilizafon monitoring

51 PROBLEMS WITH PROCESS MONITORS

52 Process Monitor Problems Temperature probes respond only to temperature not the medium they are measuring Steam environment versus air environment Temperature probes cannot roufnely be placed into wrapped loads Biological indicators have to be incubated hence do not give instant results Biological indicators typically monitor a 5 or 6 log reducfon Chemical indicators are semi- quanftafve

53 CHEMICAL INDICATORS

54 Chemical Indicator Types Class 1 indicators (process indicators) are used to differenfate processed and non- processed items Class 2 indicators (Bowie Dick indicators) confirm steam penetrafon capability Class 5 indicators perform similarly to the performance of an ISO biological indicator Class 6 indicators are used to increase the confidence in the adainment of a sterility assurance level and give assurance that the set sterilizafon parameters have been achieved

55 Bowie Dick ISO Implemented into Europe EN ISO ISO Implemented into Europe EN ISO ISO Implemented into US ANSI/AAMI/ISO

56 ISO o C Depression (Europe) Start of plateau 7 kg test pack 2 o C

57 ISO o C Depression (USA) 4 kg test pack 1 min from end of plateau 2 o C

58 Differences between Europe and US - BD European BD test packs use term steam penetrafon US BD test packs use term air removal 7 kg towel pack from Europe is much more dense than 4 kg towel pack from US Hence European test pack is much more sensifve than US test pack

59 Class 5 Performance Time (min) Slope to be 6 C to 14 C Endpoint at 121 C must be greater than 16.5 min 36.4% tolerance at each temperature point Endpoint at midpoint must be declared Endpoint at 135 C must be declared Temperature ( C)

60 Class 6 Performance 100 Endpoint to be declared Time (min) % tolerance at each stated value Endpoint to be declared Temperature ( C)

61 Sterilizer Cycle STERILIZATION AIR REMOVAL

62 SterilizaFon Plateau ICAL TOR 5 OR

63 Parametric Release If a system of parametric release is used, it is essenfal that the crifcal parameters for that process (i.e. steam) are monitored Only a Class 6 indicator can pracfcally monitor those condifons from within the pack or load.

64 REGULATORY GUIDANCE

65 ISO/TS ISO/TS SterilizaFon of health care products Moist heat Part 2 Guidance on the applicafon of ISO Provides guidance on validafon and roufne control of steam sterilizafon, including use of chemical indicators

66 SCIENCE OF AIR IN STEAM

67 Steam

68 Steam AdracFon To A Mass Steam & air mixture

69 Small Load Effect Air and steam do not easily mix Air will concentrate more into a single pack than it will into a series of packs A single load, such as a 7 kg pack of towels, will be more sensifve than mulfple packs

70 Small Load Effect

71 Steam 2,5 Pressure (Bar) 2 1,5 1 0,5 Phase boundary line Temperature (C)

72 Dalton s Law In theory, it is possible to detect the presence of air in steam by measuring and comparing the pressure and temperature 1 bar of steam + 1 bar of steam = 2 bar temperature = 134 C 1 bar of air + 1 bar of steam = 2 bar temperature = 121 C

73 Dalton s Law Values for litre sterilizer Volume of air Frac3on of air Δ P mbar 0.2 litres 0.02% litre 0.1% litres 1% litres 10% litres 15.7% litres 20%

74 CONCLUSION

75 SterilizaFon Monitoring We sfll have the same problems to monitor as we did 50 years ago! We now have 2 advantages: Far greater understanding of the process RecogniFon that a single process monitoring approach is not sufficient Accurate means of monitoring the process Using the appropriate process monitor

76 STEAM Utopia! ValidaFon of the process Thermometric qualificafon Performance qualificafon (PQ) of loads Microbiological qualificafon (only for specific loads) Daily steam penetrafon test (Bowie Dick Test) Monitoring of each cycle Thermometrically (drain probe) From within pack using Class 6 indicators Review of data and parametric release of load

77 Thank you! Ques3ons?