Steam Sterilization Effective and Reproducible. But is it?

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1 1 Steam Sterilization Effective and Reproducible. But is it? René Vis CSSD Project manager international Miele Professional International

2 WFHSS 2016 Brisbane 2 Porous load sterilizers Porous-load sterilizers are distinguished from other hightemperature steam sterilizers by the following features: As porous loads trap both air and moisture, the sterilizer has a vacuum system to ensure that sufficient air is removed from the chamber and load before steam is admitted to the chamber.

3 WFHSS 2016 Brisbane 3 Some Basics of Steam Sterilization A steam sterilizer Process examples Dynamics in process Steam Quality Validation and monitoring

4 R. Vis Oct 4th 2016 WFHSS 2016 Brisbane 4 What defines a steam sterilizer Besides the computers controlling and monitoring the processes there are: Steam as a sterilizing medium ( steam-steam converter/electrical) Directly from the hospital Integrated in the sterilizer (on top, under chamber) Separate steam generator Chamber and jacket How steam enters the chamber Directly into the chamber Via the jacket Vacuum system Vacuum pump ( one or two stage water ring pump, others) Venturi system

5 WFHSS 2016 Brisbane 5 Processes are like fingerprints

6 WFHSS 2016 Brisbane 6 Reproducibility of sterilization processes The reproducibility of the sterilization process can be affected by a variety of factors: deviation of the defined cycle parameters, retention of air in the load, air leakage and non-condensable gases in the steam, excessive accumulation of non-condensable gases and/or condensate, steam saturation also chemical composition, the design of the medical device itself orientation of the load type of Sterile Barrier System (SBS).

7 WFHSS 2016 Brisbane 7 Sterilisation parameters S A T U R A T E D S T E A M

8 WFHSS 2016 Brisbane 8 Defined cycle parameters The 3 stages of water: Solid Liquid gas Saturated Steam water vapor in a state of equilibrium between its liquid phase and its gas phase Saturated steam occurs at temperatures and pressures where steam and water can coexist. In other words, it occurs when the rate of water vaporization is equal to the rate of condensation.

9 WFHSS 2016 Brisbane 9 Saturated Steam Steam quality measured periodically at defined point in steam pipe between steam generator and chamber. EN 285 requires that the amount of gases should not exceed 3.5% (3.5 ml of gas/100 ml of steam condensate)

10 WFHSS 2016 Brisbane 10 Steam supply Non-condensable gas test (Health Technical Memorandum 01-01) This test is used to demonstrate that the level of non-condensable gases in the steam will not prevent the attainment of sterilization conditions in any part of the load. Possible sources of non-condensable gases are discussed in paragraph 3.29, Non-condensable gases. The method described should not be regarded as measuring the exact level of noncondensable gas, but as a method by which the provision of acceptable steam quality can be demonstrated.

11 WFHSS 2016 Brisbane 11 Source of NCG s The main source of NCGs in the steam supply is the boiler feed-water, and the level will be greatly influenced by the water treatment employed. In order to drive off dissolved air, carbon dioxide and other NCGs in the boiler feed-water should be degassed before use by heating in a vented tank (a hot well). This will also break down bicarbonate ions, driving off further carbon dioxide. For the degassing to be effective, the temperature of the feed-water should not fall below 80ºC at any time.

12 WFHSS 2016 Brisbane 12 Current ways of NCG detection (EN ) Air detector, small load When tested as described in 19.2 an air detector shall cause a fault to be indicated if the volume of air or other noncondensable gases retained or introduced into the sterilizer chamber during the air removal and steam admission of the operating cycle causes a difference in temperature of more than 2 K. This difference is evaluated between the lowest measured temperature in a standard test pack and the temperature measured at the reference measurement point of the sterilizer chamber at the commencement of the equilibration time. Measuring NCG s as a derivate of a temperature difference

13 WFHSS 2016 Brisbane 13 EN air detector test Carry out an operating cycle but during the air removal stage admit air to the sterilizer chamber by means of the metering device. Control the rate of entry of air so that, at the start of the plateau period, the temperature measured at the center of the test pack is not more than 2 K lower than the temperature measured at the reference measurement point. Question is here do we really want to use the test pack as a reference for our current loads?

14 WFHSS 2016 Brisbane 14 Other causes of NCG s Air detector fault (Health Technical Memorandum 01-01) The air detector is designed to register a fault when the level of air and gas sampled from the chamber is high enough to affect the even and rapid penetration of steam into the load. Possible causes of an air detector fault include: a. an inefficient air removal stage; b. an air leak during the air removal stage; c. non-condensable gases evolved from the packaging; d. non-condensable gases in the steam supply; e. a defective air detector.

15 WFHSS 2016 Brisbane 15 Chemical indicators? Use of chemical indicators 2.91 Chemical indicators are designed to show by a change of colour whether specified sterilization conditions have been attained Chemical indicators by themselves are insufficient to demonstrate the efficacy of a sterilization processes.

16 WFHSS 2016 Brisbane 16 Biological indicators? Use of biological indicators Biological indicators are designed to show whether specified sterilization conditions have been attained, by the survival of test microorganisms. However, they should not be used for routine monitoring of steam sterilization processes. In exceptional circumstances where the use of biological monitors could be considered, advice should be sought from the Microbiologist (Decontamination)..

17 WFHSS 2016 Brisbane 17 BI/CI passed here.

18 WFHSS 2016 Brisbane 18 Current state of the art / best practice Control and monitoring of time, temperature, pressure. Periodical thermometric validation Or do we need continues monitoring of steam saturation during the holing time of each cycle?

19 WFHSS 2016 Brisbane 19 Validation of the processes Validation ( EN-ISO 17665) documented procedure for obtaining, recording and interpreting the results required to establish that a process will consistently yield product complying with predetermined specification

20 WFHSS 2016 Brisbane 20 Steam quality EN 285 Non-condensable gases in steam Dryness of steam Steam/condensate chemical sampling Feed water chemical sampling

21 WFHSS 2016 Brisbane 21 Medical devices to sterilize IFU compliant with ISO Sterile Barrier System (SBS) ISO Tray configuration Load configuration Validation loads Location and placement of thermocouples

22 R.Vis Oct 4th 2016 WFHSS 2016 Brisbane 22 Phaco hand piece reprocessing Design of MD is challenging to actual sterilization processes Publication of case study on orientation of phaco hand pieces during steam sterilization. Due to high insulation value of the hand piece too much condensation was formed and sterilization conditions could not be achieved inside the instrument. This case study resulted in hospitals individually wrapping the hand pieces and placing them in a vertical position during sterilisation.

23 WFHSS 2016 Brisbane 23 Tray configuration The tray and the way instruments are placed or fixated in the tray can deviate from previous validated processes

24 WFHSS 2016 Brisbane 24 Load configuration The way the individual trays are placed in the load can have an effect on the results too. Heavy trays below light trays The use of tray-liners or absorbent fields Protective layers for transport Loading protocols

25 WFHSS 2016 Brisbane 25 Location and placement of thermocouples The placement and position of the thermocouples is crucial for reliable results. Type of fixation to the instrument, sort of adhesive tape Full contact with the surface of the instrument

26 WFHSS 2016 Brisbane 26 Validation results Results are measured against EN 285 and ISO requirements Focus is on the sterilization holding time All temperatures should be within specifications. Equilibration time is 15 sec <800 liters, 30 sec >800 liters.

27 WFHSS 2016 Brisbane 28 What about the daily/weekly tests? B&D test Steam penetration test, daily Leak test Testing the chamber for air leaks, daily/weekly Biological indicators Biological indicators in cycle Biological indicators in trays Both don t represent sterilization conditions at instrument level Chemical indicators Tape and indicators on pouches No indication that sterilization conditions are met Integrators in trays Mostly used by demand by the end user Don't represent sterilization conditions at instrument level

28 WFHSS 2016 Brisbane 29 Daily/weekly test in relation with validation Validation is providing the proof that sterilization conditions are met at instrument level Daily/weekly tests provide ongoing information that the conditions measured at validation have not changed Biological and chemical indicators are indicators Representing temperature conditions only at the place they are placed within the load or tray The indicators support the validation results

29 WFHSS 2016 Brisbane 30 Conclusions Steam sterilisation is based upon the presence of Saturated Steam as described in EN 285 in the chamber and load. The presence and penetration of saturated steam should be monitored and assured in every load. Only time (1), temperature (2) en pressure (3) to measure sterilisation conditions is not sufficient Measuring saturation of the steam

30 WFHSS 2016 Brisbane 31 Last but not least A look into the (near) future: In the presence of saturated steam and proven penetration in-process periodically thermometric re-qualification will no longer be necessary. Chemical and biological indicators will lose their importance and will have no additional value to the quality management of reprocessing. There will be a need and demand for automated and dedicated cycles for specific product families: ISO AS/NZS 4187:2014 Saving cycle time and reducing total reprocessing time and costs.

31 WFHSS 2016 Brisbane 32 Thank you for your attention

32 WFHSS 2016 Brisbane 33