Sterilisation and Disinfectants - 1 MBBS march 2022 MONDAY.pptx
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Sterilisation disinfection
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Sterilisation and Disinfectants - 1 MBBS march 2022 MONDAY.pptx
- 2. Sterilization and disinfection -1 Classify & describe various methods of sterilization methods Discuss various methods of disinfection, Classify disinfectants, List out Testing of disinfectants, Describe Plasma sterilization Define & applications of Fumigation, fogging Specific learning objectives: MI 1.4,1.5
- 6. Cleaning The removal of visible soil from objects - manually or mechanically using water with detergents or enzymatic products.
- 8. Decontamination • According to OSHA, • “the use of physical or chemical means to remove, inactivate, or destroy bloodborne pathogens • on a surface or item • to the point where they are no longer capable of transmitting infectious particles • and the surface or item is rendered safe for handling, use, or disposal” • In health-care facilities, the term generally refers to all pathogenic organisms Occupational Safety and Health Administration
- 9. Disinfection A process that eliminates many or all pathogenic microorganisms, with exception* of bacterial spores, on inanimate objects. • In health-care settings, objects usually are disinfected by liquid chemicals or wet pasteurization • Usually a chemical agent (but sometimes a physical agent) that destroys disease-causing pathogens or other harmful microorganisms & • Exception* level of disinfection - Disclaimer*– high level chemical sterilants do bacterial spores. Germicide includes both antiseptics and disinfectants. Antiseptics are germicides applied to living tissue and skin; disinfectants are antimicrobials applied only to inanimate objects Decontamination removes pathogenic microorganisms from objects so they are safe to handle, use, or discard.
- 10. Sterilization • A process that destroys or eliminates all forms of microbial life including spores! • by physical or chemical methods • Ex. • Steam under pressure, • dry heat, • EtO gas, • hydrogen peroxide gas plasma, • and liquid chemicals • are the principal sterilizing agents used in health-care facilities.
- 11. Practical questions - Assessing risk • What all items you see in hospitals? • Name them – heterogeneous items!! can you classify for ease! • To what extent you need them clean as per the earlier definitions? • What determines is - Patient contact with that item !! • What are the microbe factors? • Nature of organisms • Organism load/numbers! • Concentration – optimal concentration is vital • Contact time –most crucial • Temperature, stability and relative humidity • Biofilm –prevents entry of disinfectant
- 20. Autoclave (Steam) Sterilization • Principle - to expose each item to direct steam contact at the required - Steam, pressure, temperature, and time. • Types 1. Gravity displacement type - only for BMW decontamination & laboratory 2. High-speed prevacuum autoclave: Vacuum pump - instantaneous steam penetration even into porous loads. • Heat and moisture resistant items but not useful for delicate items like scopes, sharp instruments (ETO or Plasma is alternative)
- 21. Autoclave (Steam) Sterilization contd.
- 22. Sterilisation Method Type – Organism Spore STEAM Bacillus stearothermophilus ETO Bacillus subtilis Hydrogen peroxide Bacillus atrophaeus Peracetic acid Biological Indicator – not suitable Use Chemical indicators Sterilization – Biological indicator types
- 23. Ethylene Oxide Sterilization • ETO Sterilization takes place using gas diffusion technology inside the fumigation chamber under vacuum. gas concentration (450 to 1200 mg/l) temperature (37 to 63°C) relative humidity (40 to 80%) exposure time (1 to 6 hours) Time, temp, ETO concentration, relative humidity • heat-labile and/or moisture-sensitive equipments • Microsurgical instruments - Scopes • Appropriate aeration is required to remove residual ETO. Continuous currents warm filtered air – 8-12 hrs
- 24. Hydrogen Peroxide Gas Plasma Sterilization • Rapidly destroys microorganisms utilizing low temperatures without toxic residue • Used for heat and moisture sensitive items • Paper, linen, liquids – cant be sterilised • Uses radio frequency energy to vaporize hydrogen peroxide • Takes approximately one hour
- 26. • Disinfectants Classification – Chemical composition » Alcohols, aldehydes, biguanides etc – Functional » Chemosterilant, High, Intermediate, Low
- 31. *Undiluted commercial bleach products are usually available between 5.25% or 6.00%-6.15% sodium hypochlorite depending upon the manufacturer. Sodium dichloro-isocynaurate (NaDCC) tablets are also available and may be used for the preparation of chlorine solutions. There are test strips available for measuring the level of available chlorine in a diluted bleach solution to ensure the desired concentration as outline above
- 32. Air disinfection - fogging • Guidelines do not recommend routine OT, dialysis fogging/ fumigation • Good ventilation-ACH, Terminal disinfection - Adequate • Exceptions 1. Before Commissioning: Bring “new/renovated facility” into working condition. 2. Outbreaks 3. Aerosol generating procedures in room with no air changes • Used chemical • Silver nitrate, Hydrogen peroxide • Make sure, label has “ for AIR Disinfection” • & EPA approved • https://www.cdc.gov/infectioncontrol/guidelines/disinfection/updates.html
- 34. Antiseptics that should not be used as disinfectants are: • Acridine derivatives (e.g., gentian or crystal violet) • Cetrimide (e.g., Cetavlon®) • Chlorhexidine gluconate and cetrimide in various concentrations (e.g.,Savlon) • Chlorhexidine gluconate (e.g., Hibiscrub®, Hibitane®) • Chlorinated lime and boric acid (e.g., Eusol®) • Chloroxylenol in alcohol (e.g., Dettol®) • Hexachlorophene (e.g., pHisoHex®)
- 35. Not covered here Other methods – • FLASH sterilisation • Dry heat • Filtration – liquids, air • Radiation – ionization (cold), non-ionising • Incineration • Microwave & TESTING OF DISINFECTANTS
- 36. REFERENCES:
- 37. THANK YOU
- 38. Resources • Decontamination and reprocessing of medical devices resource • Decontamination and reprocessing of medical devices for health care facilities is a very important manual to provide guidance to health managers and health workers on required infrastructures and standard procedures for effective sterilization, and decontamination reprocessing of medical devices. • General resources • WHO Core component guidelines cover eight areas of IPC and comprise 14 recommendations and best practice statements. • Improving Infection Prevention and Control at the Health Facility Manual is a practical manual that outlines how to implement the Core Component Guidelines. • WHO Multimodal Strategy consists of several elements (3 or more; usually 5) implemented in an integrated way to guide action and provide a clear focus for the implementer. • WHO Infection Prevention and Control Assessment Framework (IPCAF) is a tool that can provide a baseline assessment of IPC programme activities within a health care facility as well as ongoing evaluations through repeated administration to document progress over time. • Interim Practical Manual Supporting National Implementation of the WHO Guidelines on Core Components of Infection Prevention and Control Programmes is a resource to strengthen IPC and improve the quality and safety of health service delivery through the establishment of evidence-based and locally adapted integrated IPC programmes.
Editor's Notes
- Now that you have learnt about the SDD layout, we will look at some best practices for workflow. The concept of flow of medical devices from dirty to clean must be maintained. This objective cannot be achieved in a one-room setup! Ten rules govern the SSD’s location. It should be designed to be physically separate from all other work areas and should not interfere with routine clinical practice. It should not be an integral part of any other service or treatment area, such as an operating theatre. It should not be used as a passageway. It should be purpose-specific and built for reprocessing devices, with clearly demarcated areas. It should be designed to allow the segregation of ‘dirty’ and ‘clean’ activities. It should be designed to facilitate one-way flow from the dirty area to the clean area. It should have a dedicated staff area close by for changing into workwear; the staff area should include a shower, toilet facilities and lockers. Access to dirty and clean areas – such as the inspection, assembly and packaging room – should be through separate, dedicated gowning rooms provided with hand hygiene facilities. The dirty, inspection, assembly and packaging, sterilizing and sterilizer unloading areas should be free of windows that can be opened, ledges and difficult-to-clean areas. The dirty, clean, inspection, assembly, and packaging and sterilizing areas should be designed to minimize ambient sound levels within the rooms. This requires particular attention to installation of equipment, building finishes and maintenance of machines. To understand how these rules apply to the overall functioning of a SSD unit, look at the image below. Again, a numbered legend is below to help explain the overall flow. In addition to having proper layout and workflow within the SSD, staff must be trained at the appropriate levels of activity, including using PPE and how to handle chemicals safely. This is part of the ‘teach it’ component of the multimodal strategy. Make sure the training covers all aspects of the decontamination cycle and provides technical training on all reprocessing equipment. Staff must also be trained to recognize problems and interpret validation tests (i.e., recognize failed results). When working in an SSD, it is imperative that staff are trained on occupational hazards and how to manage them. Moreover, staff working in this area require hepatitis B immunization because of the constant exposure to blood-borne pathogens. Taking such preventive measures will help to reduce and eliminate occupational threats. Staff should also receive regular training on: procedures to follow; the anatomy/construction of medical devices; the use of washer disinfectors/sterilizers; traceability systems; and the importance of record keeping.
- Instruments and medical devices are delivered to the receiving area. They are brought into the dirty area and cleaned (either manually or mechanically). Once cleaned, they are passed through the inspection, assembly and packaging area. Instruments and medical devices can only be returned from this area to the receiving area if they have not been properly cleaned. After packaging, they are put into the sterilizer. Sterilized items are taken out. Stored in a clean area to await dispatch to clinical areas.
- The last item we will cover for setting up the SSD unit is environmental cleaning. It is important to have an environmental cleaning policy for the SSD. Make sure that the policy is clearly defined by the health care facility, with clear Standard Operating Procedures (SOPs) that cover cleaning practices, who is responsible for cleaning, and cleaning frequency. To verify environmental cleaning, use this checklist with an associated validation method. Cleaning should be performed daily, moving from clean to dirty areas, and keeping the environment clean, dry and dust-free. Separate cleaning equipment should be used for clean and dirty areas. The use of disinfectants for routine cleaning is strongly discouraged. Disinfectants are recommended only when dealing with spills. All leaks and spills must be cleaned up immediately. Receipt, storage and transportation of medical devices We will move now to the first main stage of the decontamination cycle—the receipt, storage and transport of medical devices to the SSD. Before sending medical devices to the SSD for cleaning, be sure to wear the appropriate PPE to protect yourself. Remove any linen and disposable items and dispose of sharps, such as knife blades and needles, in puncture-proof sharps containers or bins. Do not use saline or hypochlorite solution as a soaking solution as this will damage some medical devices. Soaking devices in 0.5% chlorine solution or any other disinfectant before cleaning is not recommended (strongly discouraged) because: it may damage or corrode the devices; the disinfectant may be inactivated by blood and body fluids, which could then become a source of microbial contamination and biofilm formation; transport of contaminated items soaked in chemical disinfectant to the decontamination area may pose a risk to health care workers and result in inappropriate handling and accidental damage; and soaking in disinfectant could contribute to the microorganisms developing resistance to disinfectants. Soiled medical devices should be opened and kept moist. Spray them with an enzymatic spray (using PPE) and cover with a towel moistened with either water (not saline) or a foam, spray or gel specifically intended for this purpose.
- Of all the methods available for sterilization, moist heat in the form of saturated steam under pressure is the most widely used and the most dependable. Steam sterilization is nontoxic, inexpensive 826, rapidly microbicidal, sporicidal, and rapidly heats and penetrates fabrics (Table 6) 827. Like all sterilization processes, steam sterilization has some deleterious effects on some materials, including corrosion and combustion of lubricants associated with dental handpieces212; reduction in ability to transmit light associated with laryngoscopes828; and increased hardening time (5.6 fold) with plaster-cast 829. Steam circulates within the jacket space surrounding chamber • Steam enters the chamber & displaces all the air • Air and steam do not mix • As pressure increases, saturated steam contacts all surfaces , penetrates packages, & forces air out through a drain at the bottom of sterilizer • Sterilization is initiated once all air is removed • High temp of saturated steam causes microbial destruction • Proper loading is crucial to allow the steam to freely circulate • Temperature affects the time of exposure in that the higher the temperature, the less exposure time is required. • As pressure ↑ in a closed chamber, so does the temperature • If these parameters are not represented in a cycle, sterilization will not occur Proper Loading & Unloading • Proper Loading • Prevents formation of air pockets & obstructions to the circulation of steam • Proper Unloading • Hot packages are allowed to cool before being handled • Moisture will form upon contact and cause contamination • Called strike through • Do not place hot items on cool surfaces Cycle Phases • Conditioning • Air removal • Exposure • Load is heated to sterilization temp • Exhaust • Bottom drain opens and steam is exhausted • Drying • Dry heat revalorizes existing moisture & removes from the load
- The Bowie-Dick test is used to detect air leaks and inadequate air removal and consists of folded 100% cotton surgical towels that are clean and preconditioned. A commercially available Bowie-Dick-type test sheet should be placed in the center of the pack. The test pack should be placed horizontally in the front, bottom section of the sterilizer rack, near the door and over the drain, in an otherwise empty chamber and run at 134°C for 3.5 minutes. The test is used each day the vacuum-type steam sterilizer is used, before the first processed load. Air that is not removed from the chamber will interfere with steam contact. Smaller disposable test packs (or process challenge devices) have been devised to replace the stack of folded surgical towels for testing the efficacy of the vacuum system in a prevacuum sterilizer. These devices are “designed to simulate product to be sterilized and to constitute a defined challenge to the sterilization process. They should be representative of the load and simulate the greatest challenge to the load. Sterilizer vacuum performance is acceptable if the sheet inside the test pack shows a uniform color change. Entrapped air will cause a spot to appear on the test sheet, due to the inability of the steam to reach the chemical indicator. If the sterilizer fails the Bowie-Dick test, do not use the sterilizer until it is inspected by the sterilizer maintenance personnel and passes the Bowie-Dick test. Like other sterilization systems, the steam cycle is monitored by mechanical, chemical, and biological monitors. Steam sterilizers usually are monitored using a printout (or graphically) by measuring temperature, the time at the temperature, and pressure. Typically, chemical indicators are affixed to the outside and incorporated into the pack to monitor the temperature or time and temperature. The effectiveness of steam sterilization is monitored with a biological indicator containing spores of Geobacillus stearothermophilus (formerly Bacillus stearothermophilus). Positive spore test results are a relatively rare event 838 and can be attributed to operator error, inadequate steam delivery,839 or equipment malfunction.
- Steam eto plasma enough
- ETO is a colorless gas that is flammable and explosive. The four essential parameters (operational ranges) are: gas concentration (450 to 1200 mg/l); temperature (37 to 63°C); relative humidity (40 to 80%)(water molecules carry ETO to reactive sites); and exposure time (1 to 6 hours). These influence the effectiveness of ETO sterilization.814, 857, 858 Within certain limitations, an increase in gas concentration and temperature may shorten the time necessary for achieving sterilization. The use of ETO evolved when few alternatives existed for sterilizing heat- and moisture-sensitive medical devices; however, favorable properties (Table 6) account for its continued widespread use.872 Two ETO gas mixtures are available to replace ETO-chlorofluorocarbon (CFC) mixtures for large capacity, tank-supplied sterilizers. The ETO-carbon dioxide (CO2) mixture consists of 8.5% ETO and 91.5% CO2.
- Do not use the following chemicals for medical devices: chlorhexidine gluconate hexachlorophene iodophor benzalkonium chloride cetrimide quaternary ammonium compounds
- TECHNIQUE OF FOGGING, COMPATIBLITY, SAFETY, CURROSIVE, TRINING, PRE-POST CULTURE 2008: “Do not perform disinfectant fogging in patient-care areas. Category II” These recommendations refer to the spraying or fogging of chemicals (e.g., formaldehyde, phenol-based agents, or quaternary ammonium compounds) as a way to decontaminate environmental surfaces or disinfect the air in patient rooms. The recommendation against fogging was based on studies in the 1970’s that reported a lack of microbicidal efficacy (e.g., use of quaternary ammonium compounds in mist applications) but also adverse effects on healthcare workers and others in facilities where these methods were utilized. Furthermore, some of these chemicals are not EPA-registered for use in fogging-type applications. These recommendations do not apply to newer technologies involving fogging for room decontamination (e.g., ozone mists, vaporized hydrogen peroxide) that have become available since the 2003 and 2008 recommendations were made. These newer technologies were assessed by CDC and HICPAC in the 2011 Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, which makes the recommendation: “More research is required to clarify the effectiveness and reliability of fogging, UV irradiation, and ozone mists to reduce norovirus environmental contamination. (No recommendation/unresolved issue)” The 2003 and 2008 recommendations still apply; however, CDC does not yet make a recommendation regarding these newer technologies. This issue will be revisited as additional evidence becomes available.