steam sterilization- opening pandoras...
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Steam Sterilization-Opening Pandoras Box
Dr. Gerhard Kirmse
Director Technical Competence Center
Why do we think about this?
Dr. Gerhard Kirmse
• Biomedical Engineering
• Doctorate on Instrument Cleaning
• Lean Professional
• Bachelor of Business Administration
Technical Competence CenterAesculap Tuttlingen
Member of
Task Force Reprocessing (AKI- Red Brochure)
Advisory Group Reprocessing of German Government
Quality Task Force of German Society for Reprocessing (DGSV)
DIN Committee Cleaning and Disinfection
Research and Consultingon Reprocessing
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We press the button and Instruments get sterile…..
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How can we be sure? - Understanding Process and Precautions
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CDC – Warning: Immediate Need for Healthcare Facilities to Review Procedures for Cleaning, Disinfecting, and Sterilizing Reusable Medical Devices
• Training
• Regular Audits
• Sufficient Sets for procedures
• Tracking
• Consult with CSSDs before purchase
• Documentation
• Maintenance and Repair
• Repair by Third Party
• Emergency procedures
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How does it work?
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Inactivation by moist heat ….
•more reliable than low temperature
•limited inactivation of prions• Validated Process
• Sterility can not be seen
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Meaning- Product Validation- Process Validation
A validation proofs that:
a Process
which is completely described by Parameters
Input Process• Parameter
Result
which is completely described by Parameters
with fixed Input
will always give the same Results
Validations are used if a process result is important but can not be measured continuously with reasonable effort
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Performance Qualification
Demonstrating that desired results are achieved in all partsDemonstrating that desired results are achieved in all parts continiously
Physical , microbiological……
Multiple runs
• Guidelines by AAMI / DGSV / ISO17665
•? standard deviation
Typically once per year3 runs
Parameters !
•Load
•Pre-Condition
•Material
•Packaging
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Standards
• EN285: large steam sterilizers
• equipment, steam supply etc.
• testing process challenge devices
• ISO17665: Steam Sterilization of Health care products• ISO17665: Steam Sterilization of Health care products
• -1: Validation and Routine Control, Definitions
• -2 Application, -3: Families
• EN554 replaced
• ISO 11607 -1 Packaging Material, requirements and test methods
• EN868 Sterilization of Medical Devices
• -2-10: requirements and test methods for various sterile barrier materials
• ISO11138; biological Indicators, performance, qualification etc
EN866 U f bi l i l i di t• EN866: Use of biological indicators
• ISO 11140: Chemical Indicators, classes
• EN 867: Use of non-biological Indicators in Sterilizers
• Process Indicators, BD tests, Steam Penetration Test
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Half-Cycle Testing
For a BI of : 2.0 X 106 et Dvalue* of 1 minuteSurvival
Example
Survival After 1.0 minute = 200,000 After 2.0 minutes = 20,000 After 3.0 minutes = 2000 After 4.0 minutes = 200 After 5.0 minutes = 20 After 6.0 minutes = 2 After 7.0 minutes = 0.2
Total time to reduce to zero = 6.5 minutes
For steam sterilization at 134°C and geobacillusstearothermophilus D=0,4min => 6-log = 2,4min
ResistometerF-value for heating time
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Hygienic Impact
• Clean
• typical Test: Geobacillus stearothermophilus
• destruction of macromoelcules
Resistance against moist heat much less than dry heat
• Contact
• Time
• Temperature/ Pressure
Comparison• Hot Air Sterilization
Plasma Sterilization• Concentration• Surface• Time• Temperature• Weight
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Philosophies of desired total F-Value (Process Lethality)
Bioburden / Combination Approach:
Number of naturally occurring microorganisms. (population) (to be tested ISO11737)
Heat Resistance of naturally occurring microorganisms. (D-value)
Change in heat resistance w.r.t. temperature changes. (z-value)
Verfication (sterility test on product ISO11737)
Overkill Approach (used for heat resistant products)
Assumption: less than 106 as original population (on very high end)
D-Value =1 (very heat resistant)
F-Value = 12 log steps (safetey 106)g p ( y )
Leads to sterilization cycle 134°C, 5min
Desinfection 5 log steps• thermal desinfection (parametric or biological)• chemical or thermo-chemical ( parametricor biological testing)
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Sterilization Effect
1. Air removal
• Pre heatingT
T =
Air
2. Bring surface of product to a temperature of 134°C to 137 °C
T Air
3. Drying
T
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Typical Cycles
Pre-Treatment• Pre-Vacuum: 3-5 Pulses, all negative or part positive• Gravity: only positive
T
Bioiling temperaturedecreases with
pressure
DRY !
Sterilization:• 134° 5min: Instruments etc• 134° 18min: Instruments CJD (France, Switzerland)• 134°C 3min (NL, UK)• 132°C 4min USA• 121° 30 min: Anesthesia equipment• 143 ° 3min: Flash, single unpacked instruments
T
Drying• Vacuum
» Small sterilizers: 10-18min» Large sterilizers: 20-30min
Fractioned Vacuum (large): 20-45min
Air has to be removedotherwise no contact between
steam and product
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Sterilizer Chamber
steam
inlet
condensate
inlet
Chamber should be clean (sign of steam impurities such as silicate)
even steam distribution is crucial
condensate has to be removed
valve
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Reference Geometry Product Testing
Standard 132°C, 4min
few critical geometries
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How to test?
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Sterilization Verification: Test Methods
•Parametric: Test, if desired temperature (e.g. 134°-137°C) is reached
•Chemical Indicators
• Process Indicators
• integrating indicators
• emulating indicators
• Biological Indicators
• Incubation Time
• Steam Penetration Test
• Bowie-Dick- Test
• Lumen Test
• Sterilizer Vacuum test
• ( Non –condensable-Gas test)
• (Steam Dryness Test)
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Prozcss -Indicator
• Chemical (Class 1)
• Physical
• Change at about 80°C, depending on time
• Has the pack been in a sterilization process or not
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Test Methods: Parametric Testing(Validation)
•Test, if desired temperature (e.g. 134°-137°C) is reached
• all loads
• empty
• max load porous goods (max. steam cosnumption)
• max load metal goods (max heat required)
• small load porous goods (air removal)
• small load lumina (air removal)
• mixed loads
•all types of goods
large palstic, hollow
worst caseyp g
• metal, plastic, porous
• all sterile barrier systems
• most crtical
• cotton packs
• heavy and hollow plastic partsporous
DocumentaionWhat? Weight?
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Validation (EN554, ISO 17665 and EN285)
IQ: Installation Qualification (upon set up)
OQ: Operational Qualification (Sensors, sealings etc): typically with maintenance
PQ: Performance Qualification
Test Loads
• maximum difference in chamber 2°C, one spot 1°C
• 134°-137°C saturated steam
• maximum delay 15/30s depending on chamber size (800l)
typically 12 to 20 thermocouplers (or loggers) , repeated runs
Microbiological Validation no longer used
• half cycle
• potential errors
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Parametric Release
• Parameters must be defined
• Trained Personnel
• Layout
• Discussion with manufacturer
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Bowie Dick Test
•described in EN285and AAMI• qualification ISO11140q• after Warm up cycle
• special cycle• electronic BD Tests
• plus visual inspection(seal, chamber,…)
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Daily Inspection: Chambers of Horror
p
•Proper work instructions
•Sign off sheets
•Proper time calculation
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Helix Test
Watch for Cracks and damages !
usually spiral tube (3m, 1,5mm inner )
• at the end: chamber with chemical indicator (should be small)
•checks air removal, not standardized
• used per day or per load
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Steam Sterilzation Chemical Indicators
Classe by ISO11140 and AAMI ST60
• Class1: process indicatorp(temperature time combination, roughly)processes or not (outside packs)tapes, seals etc.)
• Class2: special Indication (BD etc)
• Class 3: single variable
• Class 4: muti variable
• Class5 integrating: temperature, steam andtime, reference to Biological indicators
Cl 6 l ti l 5 b t• Class 6 emulating: as class 5 but noreference to Bis
Class 5 and 6 are used: inside packs, in Helix/ BD Tests, in clritical areas
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Where to place?
In Chamber
• immediately readable
• definitely not worst case
sterilization parameters were generallymet
In Sets
• check before usage (? cosnequences)
• have to be easy to find
• forgotten
• usually not worst case positions
• Lumens
• undeneath Plastic parts
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Biological Indicators by ISO11138 /14161
• Bacteria Population: „Dead Bugs dont lie !“
• Sterilize Test Pack
• Incubate (1-24h)
• Read-out
• may be in challenge packs
• ca 105 -106 spores
• D-Value of 10-25s at 134°C
• 0,5-2,5minmin holding time to pass
• additional effect by heating phasey g p
• Validation: Resitometer and half cycle test
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Downside of BIs
• accuracy +/- 20%
•only short sterilization times necessary
• long waiting time before release
• Complicated handling
• false growtth situations (fails)
• expensive
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Indicators in general
biological indicators
• exact replication of task
• expensive time consuming• expensive, time consuming
chemical indicators
• parameter based
• models
• immediate
• no reaction regarding drying• no reaction regarding drying• local reaction, does not
necessarily represent the entire load
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Cost Comparison (check your own situation)
Test Cost Daily Cost Information
Assumption: Sterilizer with 10 STE used for 8 loads per day, Daily Costmaterial and work time, based on €20/h
Checkfor validation Cost: €3000/ by 2000 loads per year: €1,50 per load
Test Cost Daily Cost Information
Validation €3000/year €12 Sterilizer Performance
Parametric Release 48min /day €16 Sterilization, Drying, Documentaion
BD Test €2-8/piece10min
€6-12 Steam penetration porous
Helix Test Per load €0,50/piece €4 Steam penetration lumen
Cl 1 t €0 10/ i €8 P /Class 1 per set €0,10/piece €8 Process ves/no
Class 6 per set €0,60/piece €48 Sterilization per set
BI per day €6 /piece10min
€9,30 „Sterilization performance“
BI per Impl set 4x/day €46,50 „Sterilization performance“
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Surface Changes in Sterilization
Products get stained and rusty…..
transfer of foreign material on sterilized goods
steam
packaging
other sterile goods
remaining moisture
material changes
Filter
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Pure Steam
inside Sterilizer
central: in/ outside hospital
Pipework: Stainless Steel
Deimieralized Water
typically two geenrators
water exchange by conductivity (salt disposal)
water exchange by time (mud disposal)
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Functiom of Steam Generators
Black Steam –Pure Steam
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Rising Risk to transferimpurities into the steam
Improvement Boiler Water• Salt Disposal: Conductivity Sensor,irrigation at max conductivity• Mud Disposal: by time (important for silicate)
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Reasons for Corrosion
Corrosive Media (Concentration)
Disposal
( )
x Temperature
x Contact Time
Corrosive- Load < > Corrosion Resistance (Material)
SterilisationDisposal
• Pre Cleaning
• Waiting Time
Manual Pre Cleaning
• Exposure Time
• Brush
Sterilisation
• Steam Quality
• Drying
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How to keep control ?
• How many instruments?
• What is it?
• Are there common demoniators between instruments affected?affected?
Type / manufacturer of instrument?
Department where used?
Process?
• Can a reason be found within the process?
Inspection Result Date / Name
Age / repair Set Item Code Description
Age / repair / Machine Issue Action
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Drying of Sterile Goods
Standards on Drying Results
EN285: Weight gain of 0,2% of a reference container in the worst position of the chamber in a fully loaded chamberchamber
Sterilizer: Must be able to dry reference container
Packaging: Must dry better than reference container with same content
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Dry Time
• Efficacy ?
• Material Influence?
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Products stay moist…..
Steam distribution in the chamber Sterilizer CycleWet Steam Chamber load
• Manufacturer recommendation• Manufacturer recommendation (Getinge standard 9kg / STU)
Position in the chamber Material Packaging Ventilation of packagingWeight of Material per container
Pressure changes
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Drying
Beispiel Reinigung ?
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Does ist stay sterile ?
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Products do not stay sterile
Sterile Barrier system ISO 11607
• Container (Hard Packs)
• Soft Wrap
• Material. Cotton/Paper/Poypropilene /Mix
1. Steril Barrier
2. Protection Layer
• Paper/ Foil
• plus Protection
• Expiry Dates vary
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Sterile Barrier Validation
• Time• environmentalcondition
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Soft Packs
• Proper Folding
• Germany: Validation
• Risk of Damages
• Transportation
• Handling
• Carrying
• Pulling / Pushing in Shelves
• no stacking
• Check before Procedure
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Container
Sterile barrier and Protection
Robust transport and storage solution
Easier Logistics (handling, coding and tracking)g ( g g g)
• require cleaning and disinfection• visual check upon packing
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Storage situationEvent related expiry dates
Sterile stock with sterile containers
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Risk Management
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Risk-Evaluation/ Risk-Management
nce
ISO14971
Risikografik
Pro
baba
ility
of O
ccur
e
Part ofQuality
ISO14971Risk-Management for
Medical Devices• Risk Analysis
• Risk-Evaluation• Risk-Management
yManagement
SystemConsequences of Occurence
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Sterilization Process
Risk Consequences Probabaility Mesaures
Non-sterilized setsget into sterile
Only disinfectedstatus of load / set
Depends on logistics
Process indicatorsCI in setget into sterile
stock/ ORstatus of load / set logistics CI in set
Defective Barrier Recontaminationof set
Depends on logistics, up to 5%
Rigid barriersystems
Wet Set Set not usable Depends on settings
Validation(BD test)
Leakage ofsterilizer
Parameters not reached in
Depends on wear Parametric Rel.(BD Test)
particulargeometries
Helix test
Lack of Steam Parameters not reached, load
Depends on installation
Parametric Rel.Helix testCI, (BI)
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Risks 2
Risk Consequences Probabaility Mesaures
Overload Wet sets, paarmeters not
User related Validation(CI, depending on
met in soem sets position)
Unsuitable goods(packaging etc)
paarmeters not met, soem sets
User related Validation
Non-condensablegases
paarmeters not met, all sets
Installation related (BD test)Helix Test
Wet steam Wet sets Installation related (Validation)(BD test) (?)
Vacuum not reached
Wet sets, sterilization notreached
Installation related(rather frequent)
(BD test)Helix Test
Sensor failure paarmeters not met, all sets
Sterilizer Related (Parametric)Helix Test
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Finally: This is all so complicated…
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Summary
Recommended:
• Validation
• weelkly/ monthly Vacuum test
• daily visual inspection
My Opinion:There is no real benefit
with the us of BI in steam sterilizationy p
• daily Bowie-Dick Test
•Helix test per load
• Parametric Release
• Process indicator per set
Reporting System on_
• sterilizer errors
• wet sets
There may be a benefit if the relationbetween parameters and sterilization
effect is not 100% clearmay be: Plasma Sterilization….
wet sets
• surface changes /corrosion defects
• defective packaging
not recommended
• bilological indicators
• class 5/ 6 indicator per set59Aesculap AG
In case of reprocessing Questions- contact TCC Team
• Processs Analysis
• Process Optimization
• Product Analysis
Dr. Gerhard KirmseEngineer Biomed. Technology
Sarah MattesProcess-Engineer
• Reprocessing Training
• Scientifc Research / Presentations
• technical Process Investigation• Evaluation of Risks
Kai TebbeDiplom-Biologist
Angelika MoserCustomer Requests
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Metrological Process Analysis
Instruments
WD -Process
Sterilization-Process
FlowSampling
Media Analysis
OR• Organization• Handling
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Check new Processesand after Changes …
We found
•Shreds and corrosion in pipes..
• wrong connection of pipes
• faults in programs (no rinse)• faults in programs (no rinse)
• wrong dosage
• mix up of cannisters
• leakages of valves/ chemistry
• poor vacuum in sterilizer
• mud disposal / salt deisposal
• inappropriate drying
l k f it• lack of capacity
• conatiner process
• lack of space (carts..)
• interfaces / waiting time
• transportation
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