SBS Design Considerations for Autoclave Sterilization Gregg A. Mosley Biotest Laboratories, Inc. Minneapolis, MN March 2-4, 2010 www.healthpack.net
Information and Time How to put 2 days of information into 30 minutes of presentation? 2
Interrelated subjects Autoclaves, or Moist Heat Sterilizers Compatible packaging Product Load 3
Guidance Documents ANSI/AAMI ST79: 2006- Comprehensive guide to steam sterilization and sterility assurance in health care facilities ANSI/AAMI ST8: 2008- Hospital steam sterilizers 4
Courses of Interest AAMI Industrial Sterilization for Medical Devices. 2010, May 11-14, Minneapolis. Four days on sterilization methods & validation, packaging and related subjects
Sterile Barrier System- Definition 3.22 Sterile Barrier System (SBS) Minimum package that prevents ingress of microorganisms and allows aseptic presentation of the product at the point of use. ANSI/AAMI/ISO 11607-1 6
Types of Sterile Barrier Systems (SBS) for Healthcare Facilities Porous, flexible pouches Rigid, porous reusable sterilization containers Biohazard containers/bags Rigid non-porous containers 7
Purpose of an SBS Package Allow for sterilization Maintain sterility until the product is used Protect the product Provide: Product identification Instructions for use through labeling and graphics Allow easy opening and dispensing Aseptic presentation and delivery 8
Historical Development of Moist Heat Sterilization First steam sterilizer (autoclave) developed in late 1870 s (Louis Pasteur's lab). Essentially no change in the process since that time. Advances achieve better control of: Water & steam quality Steam supply Temperature distribution Elimination or mixture of air 9
AMSCO Eagle Steam Sterilizer Example - Moist Heat Sterilizer 10
Definition - Moist Heat Heat that is derived under conditions of saturated H 2 0 (100% RH), either: Liquid or Steam under pressure. No saturation NOT MOIST HEAT 11
Critical Factors for Moist Heat Sterilization Factors that affect microbial lethality Moisture Content (100% RH) Time (Varies with temperature, cycle type, products and packaging) Temperature (121C [250F], 132 C [270F] or 140C [common in Europe] AIR 12
Air Can prevent: Even and adequate energy transfer Moist heat effects to impart microbial lethality Must either: Removed during sterilization or Homogeneously mixed with SATURATED steam (Not appropriate for porous goods) 13
Empty, Sealed 1 L Bottle Moist heat outside, Dry Heat Inside 14
Moist vs. Dry Heat Dry Heat is approximately 500-1000 times LESS effective than moist heat. Cycle times AT THE SAME TEMPERATURE would take 500-1000 times longer to achieve the same sterilization efficacy
Important Process Parameters Moist Heat Sterilization Parameters that must be measured and controlled during processing Moisture Temperature Time Pressure Pressure change rates Air removal Cycle Selection, partly controls 16
Two Types Air Elimination Surface Sterilant 1. Gravity Displacement Requires major attention to load and arrangement May be needed for product tolerance issues May be an equipment restriction 2. Dynamic Air Removal Pulls (pre-vacuum) or pushes (pulsing positive pressure) air out of chamber and load 17
Temperature/ pressure Gravity Displacement with Vented Steam Purge Vent closure Sterilizing temperature Saturated steam pressure a) b) c) Time ANSI/AAMI ISO 17665-1: 2006 Annex E - Example of saturated steam sterilization cycle - vented system 18
Temperature / pressure 3 Pulse Pre-Vacuum Sterilizing temperature Saturated steam pressure Atmosphere 0 a) b) c) Time d) e) f) ANSI/AAMI ISO 17665-1: 2006 Annex E - Example of saturated steam sterilization cycle - with vacuum pressure pulse air removal system 19
Temperature Select temperature range and cycle type based upon: Product tolerance Packaging tolerance Bioburden or relationship of bioburden to BI Equipment available Organisms die more rapidly at higher temperatures 20
6 Theoretical Effects of Changes in Moist Heat Temperature on Microbial Lethality for Geobacillus stearothermophilis 5 4 3 2 D = 0.02 min, 141C D = 2 min, 121C 1 D = 0.2 min, 131 C -1 0.12 1.2 6 12 Time, minutes 21
General Resistance of Microbes (Moist Heat is extremely effective) Bacterial endospores (gram positive organisms) Mycobacteria Fungi Viruses Vegetative bacteria 22
Nosocomial Agents Clostridium difficile (spore former) Staphylococcus aureus (MRSA, methycillin resistant Staph) Enterococcus spp. (VRE, vancomycin resistant Enterococcus) Acinetobacter baumannii Pseudomonas aeruginosa Klebsiella pneumoniae 23
Moist Heat Breathable Packaging External moisture as source Packaging must allow for effective gas transfer. Generally breathable material such as: Tyvek Paper Transparent side Hybrid plastics 24
Critical Packaging Criteria 1. Maintain the product integrity Barrier integrity Product protection 2. Maintain sterility Package integrity Seal integrity Seal strength 3. Appearance Labeling and graphics 25
Material Qualification Sterilization Process Effects Moist Heat Paper dimensional stability, wrinkling and distortion Tyvek not recommended, begins to soften or embrittle below 270 o F Most 270 F cycles will run up to 274 F 26
Example - Types of SBS Porous, Flexible Packages Using Paper or Tyvek MUST allow gas penetration for a sterilization processes Air out H 2 O in! 27 Photo courtesy of PACE Solutions, LLC
Examples of Example - Types of SBS Porous, Flexible Packages
Flexible Packages, Adhesive Sealing Strip
Allows Self-Sealing
Chevron ends allow aseptic delivery
Paper has low tear strength & wet is worse
Example -Reusable Rigid Sterile Barrier Systems Sealed closure system Employs filters covering sterilization (venting) ports 33 Photo courtesy of PACE Solutions, LLC
Example -Reusable Rigid Sterile Barrier Systems- Wrapped
Rigid Trays Load Configuration: Biological Indicator Placement BI #1 BI #2 BI #3 35
Rigid Trays Load Configuration: Biological Indicator Placement BI #4 BI #5 BI #6 BI #7 BI #8 BI #9 BI #10 36
BI #1 BI #2 BI #3 BI #4 BI #5 37
Rigid Trays & Rubber Mats 38
Air Compression in Container with Gravity Cycle Red = High temperature steam White = Lower temperature non-saturated RH Green = Lowest temperature air 39
Air Compression in Container with Inadequate Vacuum Cycle Red = High temperature steam White = Lower temperature non-saturated RH Green = Lowest temperature air 40
Moist Heat as Sterilizing Agent Surface Sterilant Only for contact with surface Air must Eliminated External moisture as source. Packaging must be permeable to allow moisture entry and exit. 41
Product Considerations For non-liquid products in breathable packaging, product/ package must be dry at conclusion of cycle. Flash off of steam at release of pressure in chamber Drying from heat in walls of chamber (jacket of chamber has steam in it) or forced, filtered air Product close to ambient temperature to prevent condensation when touching cooler surfaces after cycle? Cool down best accomplished in chamber with door closed? 42
Design & Placement Considerations Contact With Surface Items must be designed to allow contact No channels without openings Density not too high, if porous material Sufficient clearance at mated parts or designed to remain sealed off Package placement Placed in package to allow air removal, if necessary for process Placed in sterilizer to facilitate air and steam removal, not overcrowded 43
Cautions Breathable Packaging Don t Do Occlude breathable surface Put non-breathable labels over breathable sections of the packaging, if possible. Wrap or surround product with non or poorly breathable materials such as poly bag Ensure breathable areas are properly aligned for double bagged material 44
Purpose of an SBS Package Allow for sterilization Maintain sterility until the product is used Protect the product Provide: Product identification Cautions Instructions for use through labeling and graphics Allow easy opening and dispensing Aseptic presentation and delivery 45
Help the OR attendants Otherwise they feel they need someone stronger to help with opening the packages Tu tu & His apprentice Lefty
THE END!
Commercial Steam BIs Spore Suspension Self-contained BI (surface) Spore strips Self-contained BI (liquid) 50
Microbiological Monitors for Moist Heat (See Annex D, 17665-1:2006) General BI used are spores of Geobacillus stearothermophilis. But other spores may be used if they are more resistant than your bioburden, and especially when processing at lower temps than usual for Geobacillus stearothermophilis (121 C or above). Clostridium sporogenes Bacillus subtilis 5230 Bacillus coagulans Bacillus atrophaeus 51
Steam Heat vs. Dry Heat Bacillus subtilis Steam D-Value at 121 C ~ 0.3 min Dry Heat D-Values at 160 C ~ 2.4 min (assumes 20 min. Z- Value) at 140 C ~ 24 min at 120 C ~ 240 min Steam is approximately 100 to 1000 times more effective than dry heat 52
Importance of Determining Bioburden The higher the bioburden: Higher sterilization time or dose. Greater the probability of significant levels of toxins or deleterious effects on the product. The more resistant the groups or species in the bioburden population Higher the sterilization time or dose. 53