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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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