Medical Market Laboratory EMEA

Transcription

1 Medical Market Laboratory EMEA Space for 3M Montage Penetration tests according to the ISO Josephus P.C.M van Doornmalen Gomez Hoyos Croatia, March 27, 2009

2 Outline Purpose penetration tests Original Bowie and Dick test Alternatives for original Bowie and Dick test Norms Conclusions 2

3 Sterilization conditions Sterilization conditions: 100 % saturated steam At the aimed temperature, e.g., 134 C For the right amount of time, e.g., 134 C for 3 minutes On all surfaces Textile fibres Inside of tubes 3

4 The task of the BDT The task of the BDT is to check pre-vacuum sterilisers independently from their own gauges etc. for: Air removal Steam penetration Routine (Daily) test for (steam) sterilizer Steam? Air 4

5 The History of the Bowie and Dick Test First mentioned in 1961: "Recent Developments in the Sterilization of Surgical Materials"; Report of a symposium organised by the Pharmaceutical Society of Great Britain Description of the Test in 1963: "THE BOWIE AND DICK AUTOCLAVE TAPE TEST" THE LANCET, March 16,

6 The original Bowie and Dick Test Pack 29 "Huckaback-Towels" Each 36 x 24 inch in size (91 x 61 cm) Washed prior to the test Unfolded and aired prior to a test for at least one hour Folded 3 times to give 8 layers Stack 11 inch high (28 cm) 6

7 The original Bowie and Dick Test Pack 2 lengths of 12 inch (30 cm) autoclave tape, "type 1222" (Minnesota Mining and Manufacturing Company) In the form of a St. Andrew s cross on a sheet of unglazed paper In the middle of the stack 7

8 The original "Huckaback Towel Pack" as set up by Dr. J. H. Bowie and Mr. J. Dick THE BOWIE AND DICK AUTOCLAVE TAPE TEST, The Lancet, (1963), S.586 8

9 Reasons for BDT failure Bad vacuum Leak Non-condensable gases 250 ml residual air 9

10 Process: Vacuum assisted sterilisers Pressure Phase 1: Conditioning Phase 2: Sterilization Phase 3: Drying and pressure equilibration Time 10

11 Bowie and Dick: CEN Towel Pack EN 285 (26.1) Plain, bleached cotton sheets Size: 90 x 120 cm Threads: warp 30 +/- 6 weft 27 +/- 5 Stack size: 22 x 30 x 25 cm Wrapped in similar fabric Weight: 7 kg +/- 10% CEN Towel Pack 11

12 EN 285:2006+A1:2008 (E) Bowie and Dick package and test defined Dimensions Material Way of folding Conditioning 12

13 Bowie and Dick package simplified 25 cm 30 cm 22 cm 13

14 Steam sterilization process Steam injection Start of sterilization phase Steam sterilization condition Pressure Time 14 Suction

15 Air (gas mix) removal Pressure Time 15

16 Steam injection Pressure Time 16

17 Steam penetration and condensation Condensation front Gases sucked out, textile stays wet Good penetration 17 Time

18 Insufficient deep vacuum Condense front will not disappear 18

19 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 19

20 None condensable gases in steam Water vapour condenses on surfaces colder than the vapour Gases that will not condense in similar conditions are called None Condensable Gases Oxygen (O 2 ), Nitrogen (N 2 ), Carbon dioxide (CO 2 ) Possibilities of introduced in the steam: Feed water Too small dimension of steam boiler Leak in pipe work, vessel 20

21 Non-condensable gases steam steam steam steam NCG s do not change their volume during condensation. 21

22 The temperature depression Example Temperature: 130 C Temperature depression 5 K Temperature: 135 C 22 Drain

23 The Air Pocket Animation The air pocket s form is not a perfect ball, but egg shaped. 23 At 10 cm height at 4,5 cm height

24 Slow warming up Pressure Phase 1: Conditioning Phase 2: Sterilization Phase 3: Drying and pressure equilibration Time 24

25 When to perform a penetration test EN Process control and monitoring: "If the sterilization process includes air removal from the product, a steam penetration test shall be carried out at the commencement of each day the sterilizer is to be used." A.4.3 Routine monitoring and testing: "e) a steam penetration test (when specified). Note. A suitable penetration test for a saturated steam process is being prepared by CEN/TC 102. CEN/TC102 WG7 prepared EN

26 EN ISO Process control and monitoring: "If the sterilization process relies on the removal of air from the sterilizer chamber in order to achieve rapid and even penetration of steam into the sterilizer load, a steam penetration test shall be carried out each day before the sterilizer is used." A.6.2 Routine monitoring and testing: "An alternative test pack may be used providing the challenge to the sterilization process has been demonstrated to be equal to or greater than the challenge from the standard test pack described in A.3. Statements to the same effect can be found in EN 554 which will be replaced by EN ISO

27 Alternative Products Alternative Bowie & Dick Test products Increased reproducibility Constant test conditions Performance requirements are covered by a dedicated standard (EN ISO ) Disposable Test Pack 27

28 What the norms say Towel pack according to EN 285 with: an Indicator test sheet in compliance with EN ISO or alternative indicators according to EN ISO

29 Examples hollow instruments Lumen 29

30 Helix Examples Helix schematically Tube Receptacle Lumen 30

31 Lumen as representative for lumen Lumen Dimension of the tube: Length of the tube Radius of the tube Thickness of the tube Material of lumen Multi layers of different materials Heat transfer Heat capacity Dimension (length tube, radius tube) 31

32 Penetration in lumen Pressure Time Length = L 32 Length = L Closed end

33 Configuration of instruments Relatively difficult to penetrate Relatively easy to penetrate 33

34 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: 34

35 Wall thickness Wall thickness More heat capacity (e.g., more condensation) Heat transfer Research ongoing 35

36 Dimensions of tube Radius Length r Research ongoing 36

37 EN ISO and EN The helix or hollow A is postulated in the EN867-5 and is to be used in small sterilizers (type B and S processes according to EN13060) Steam penetration test for large sterilizers (EN285) should be a Bowie & Dick test or an alternative, as described in the EN ISO So far, no scientific proof has been found in literature (1). (1) Publications in a scientific journal with an impact factor 37

38 Proving for alternative tests Show that the alternative test is reacting as the original Bowie and Dick test. Experimental data Bowie and Dick test Experimental data for alternative Comparison between data Bowie and Dick test and alternative test

39 Hollow A and helix Is the hollow A of Helix a good representation of your instruments with narrow lumen? Is a postulated test Postulates for small sterilizers type B and S 39

40 Current situation At this moment there only: B&D test or alternative big sterilizers Postulated test for small sterilizers ISO working group is started to write ISO part 6 This standards is meant to address Process Challenge Devices Research concerning penetration in lumen is on going 40

41 Conclusions Penetration is a daily equipment test Penetration tests must fulfil ISO part 3 or part 4 Documented evidence for alternative tests must be available fore end-users: Experiments Data Research and data are needed 41