Current Sterilisation Process Content of the Presentation. Content of the Presentation. Prof (Col) Dr RN Basu. Content

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1 Content of the Presentation Prof (Col) Dr RN Basu Content Part 1 1. History of sterilisation 2. Sterilisation concepts 3. Classical sterilisation practices Part 2 1. Functional zones and work flow 2 Content of the Presentation Part 3 1. Current sterilisation process 2. Part 4 1. Planning and Designing Part 5 1. Quality control 2. Bibliography Current Sterilisation Process 3 4 1

2 Current Considerations Current Considerations Steam is currently considered more as an ideal candidate for sterilisation This is because of its compatibility with the environment and health and safety, It has capability of better penetration than newer methods such as H 2 O 2 or H 2 O 2 with plasma and ozone The bio burden It is the pre-sterilisation population of viable micro-organisms on an item or product, and affects the lethality of steam sterilisation. A low bioburden is important. Steam can have a non-logarithmic inactivation death curve where heat activation of dormant spores can occur initially Consequently, steam sterilisation is best performed with pre-sterilisation and low spore bioburden levels, below 1,000 CFU/device. The number of plastic materials capable of being steam sterilised will vary considerably with the selected temperature of sterilisation Standard steam sterilisation is generally carried out at 121 C for min. Faster or flash sterilisation is generally carried out at 134 C and greater for 3-4 min. A longer sterilisation or lower steam sterilisation is carried out at 115 C (for 30 min). 5 6 Sterilisation Process Superheated steam is hotter than dry saturated steam at the same pressure It is less efficient, becomes equal to dry heat Advantages of Steam Sterilisation Advantages of steam sterilisation include: It is relatively simple There are no toxic residues or wastes It requires minimum processing time It is suitable for liquid materials and heat resistant material Steam is capable of destroying all viable forms of life including prions Steam is generally the most dependable sterilant for laboratories 7 8 2

3 Disadvantages of steam sterilisation Use of steam sterilisers needs special training The steam must reach a suitable pressure for condensation to occur Steriliser loading and packing configuration is critical to performance Steam does not permeate as completely as EtO, irradiation or dry heat Steam cannot be used to sterilise materials that are impermeable to steam It may damage delicate equipment EtO and Formaldehyde probably have been the predominant method of gaseous chemical sterilisation used in healthcare Still it is second to steam sterilisation Some classical advantages of EtO sterilisation are: Used at low temperature It has good penetration and usability High level of material compatibility It is bactericidal It can sterilise some heat sensitive materials, lumens and difficult to sterilise areas 9 10 EtO has replaced formaldehyde in most situations because: it is not malodourous It does not condense It penetrates better Unlike formaldehyde, does not leave any residue EtO is cleaner than formaldehyde without its disadvantage Formaldehyde continues to be used in less modern and remote parts of the world Some disadvantages: Potential hazard to patient and user Lengthy cycle and aeration time Use of gas mixtures is required to reduce risks of explosion EtO become increasing It is slow acting It is extremely toxic and potentially carcinogenic It is flammable and explosive Its use require special equipment and processing

4 Aspects for EtO sterilisation External preconditioning Vacuum creation RH EtO concentration Temperature and pressure changes Dwell (exposure) duration Post-sterilisation aeration Requirements 100% EtO is not used for sterilisatio EtO is diluted with other gases: Addition of Nitrogen EtO in higher concentration of 10% CO2 /90% EtO has been replaced with lower concentration Example: 6% EO/94%CO2 12% EO/88% Freon Freon is now replaced with other non-ozone depleting mixture Radiation Sterilization Radiation Sterilisation Facilities at BARC Radiation Sterilization Ionizing radiation in the form of -rays from radioactive isotopes (e.g. 60 Cobalt, 137 Caesium, Electron beam, X-ray)) Also can be obtained from high speed electron beams (E-beams) produced by particle accelerators Ultraviolet irradiation was known to have sterilisation effects It can sterilise airborne microbes Gamma and electron beam radiation is used in industries but not in hospitals Russel, Hugo & Ayliffe's Principle and Practice of Disinfection

5 Ozone Ozone Its effect as an steriliser was known since long It is not stable as a gas in air except when it is very dry Because of these drawbacks it was used for water sterilisation Ozone penetration is only moderate It tends to decrease with time It needs to be continuously generated and flowed through a steriliser chamber Liquid Sterilisation The following chemicals are used as sterilants Formaldehyde Glutaraldehyde -Propiolactone Diethyl Pyrocarbonate Iodine Ozone Alcohols with Additives Hydrogen Peroxide Chlorine Sterile packaging store Packages need to be stored properly Example: Packages should not be stored near water, or wet spots The typical recommended temperature for all sterile storage for all sterile storage areas in hospitals is typically 24 0 C Such areas require at least four air exchanges per hour The controlled relative humidity should not exceed 70% (Also see ASHRAE Code later in this presentation)

6 Sterile items should be stored separately from non sterile stores Should be stored on or in designated shelving, counters or carriages Examples of good storage: At least 45 cm below the ceiling (or level of a sprinkler head) Because adequate space is needed for air circulation and to ensure effectiveness of the sprinkler systems At least cm above the floor to prevent contamination during cleaning At least 5 cm from the outside walls because of condensation during cleaning The bottom shelf should be solid or contain a physical barrier between the shelf and the floor STERILE STORAGE (TYGERBERG HOSPITAL) Heavy packages, e.g., instruments, should not be stacked due to the possibility of compression and package damage Outside shipping containers and corrugated cardboard boxes are exposed to unknown and potentially high microbial contamination They should never be allowed in the sterile storage area Wet packages should not be stored and should be removed Because many of the medical device packages if wet could allow microbes to permeate the package material Sterile packages should be stored in a manner that preserves their integrity of packing material, seal or closure s practices This can be either date or event related Some facilities continue to date every sterilised package and use shelflife practices Shelf life practices is first in, first out Other facilities have switched to event-related practices This approach recognises that the product should remain sterile until some event causes them to become contaminated Example: a package becomes torn or wet

7 Transportation of Sterile Items Chances that the content of a package will remain sterile depend on: The quality of packaging material The conditions under which items are stored and transported Amount of handling All packages containing sterile items should before use be inspected before use This is to verify barrier integrity and dryness Any package that is breached, wet, torn, dropped on the floor, or damaged in any way should not be used Even foe event related packaging, the date of sterilisation should be placed on the package Transportation Should be transported in covered containers or enclosed carts with solid bottom shelves If transported by hand, sterile packages that contain instrumentation and equipment and so on, should be kept parallel to the floor Contaminated or returned items should be contained and transported separately to the decontamination areas or soiled utility areas These should be in containers, devices, or carts They should be labelled as biohazard and should be sent away as soon as possible Dirty items should be separated from clean and sterile supplies Transportation of Sterile Items Items that need to be kept moist in a transport container should be provided with a moist towel Water should be used for moistening towel and not saline Foam, spray or gel products intended for such use Transport vehicles used for offsite transportation (motorised or manual) should be totally enclosed and leak free These vehicles should be constructed of such material to allow proper decontamination processes Such vehicles should not be used for both contaminated infectious wastes and sterile uncontaminated packages or products Thank you