Sterilization of OT

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DEFINITIONS Antiseptic  Substance that has antimicrobial activity & that can be safely applied to living tissues. Bacteriostatic  Agent which prevents bacterial growth but doesn’t kill bacteria. Bioburden  The number & types of viable organisms with which an object is contaminated.

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Biological Indicator  It is sterilization process monitoring device consisting of a standardized viable population of micro-organisms of high resistance to mode of sterilization being monitored. Chemical Indicator  It is sterilization process monitoring device designed to respond with a characteristic chemical change to one or more parameters of sterilization cycle.

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Chemosterilizers  A chemical used for destroying all forms of microbiological life including spores. Decontamination  The process by which contaminated items are rendered safe for personnel without protective attire to handle or render item safe for reuse.

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Disinfection  Destruction of many but not all micro-organisms on inanimate objects. The Center Of Disease Control & Prevention (CDC) has given 3 levels of disinfection LEVELS OF DISINFECTION LEVELS BACTERIA LIPID & MEDIUM SIZED VIRUSES NON LIPID OR SMALL SIZED VIRUSES VEGETATIVE TUBERCLE SPORES FUNGI HIGH + + + + + + INTERMEDIATE + + +/- + + +/- LOW + - - +/- + -

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Disinfectants  chemical germicides formulated to be used on inanimate objects. The Environmental Protection Agency (EPA) classified them as those With Tuberculocidal activity Without Tuberculocidal activity. Mechanical Indicators  sterilizer components that gauge & record time, temperature, humidity pressure during sterilizing cycle.

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Sterilization  destruction of all form of micro-organisms ( high temperature). Terminal sterilization  sterilization process carried out after final packaging of the item. Sterility Assurance Level (SAL)  the probability of survival of micro-organisms after a terminal sterilization process & is predictor of efficacy of the process. A SAL of 10 -6 indicates non sterile item.


ORDER OF RESISTANCE In descending order are- Prions Coccidia ( cryptosporodium ) Bacterial spores (bacillus) Mycobacterium Cysts Small non-enveloped viruses (Polio)

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Trophozites Gram Negative Bacteria (Pseudomonas) Fungi Large non-enveloped viruses (adenovirus) Vegetative Bacteria (Staph Aureus) Lipid or medium sized viruses (HIV, Hepatitis B)


STAGES IN THE PROCESS ARE General Cleaning & Decontamination. Then if required Sterilization Disinfection


CLEANING OF EQUIPMENTS Aim  To remove retained salt & organic soil which can inactivate chemical germicides or protect organisms from destruction during disinfection. Procedure  Immersible items should be cleaned under water, with or without detergent for atleast 3 min. to prevent aerosolization of organisms & those not immersible can be cleaned with cloth soaked in detergent & water.

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Disassembly - Devices should be disassembeled & jointed instruments must be opened. Cleaning- Before cleaning, manufacturer`s instruction are consulted. Tapes, soils, adhesive residues are dissolved by using appropriate solvents.

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Devices must be soaked in protein dissolving solution to prevent coagulation of blood & then it should be scrubbed thoroughly inside out. Complicated devices can be cleaned by ultrasonic cleaning after gross soil has been removed.

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Rinsing- After cleaning, rinsing should be performed; lumens & channels are well flushed during each rinse. They should be towel or air dried.


METHODS OF STERILIZATION PASTEURIZATION It’s a high level disinfectant. The equipment is immersed in water at an elevated temperature of usually 80°c for 10min or 70°c for 30min. It can`t kill all spores & viruses. So it is recommended for perishable & where absolute sterility is not required. E.g.  Breathing tubes, ETT, Reservoir bags, Face masks, Laryngoscope blades, ventilator bellows & any rubber goods.

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Precaution  Care must be taking regarding time. Addition of extra items in the middle of process should not be done. Advantage s  It is simple, inexpensive & reliable. Doesn’t emit toxic fumes It is less damaging to instruments as low temperature is required.

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Disadvantages  Items will be wet & must be dried. Prepackaging is not possible. Plastic & rubber articles loose there shape & antistatic properties because of repeated exposure to high temperatures.

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BOILING For small articles like face masks. It is suitable for metal & also for rubber & neoprene items. Instruments are boiled in water for 5-15min for destruction of vegetative matter.

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FILTRATION Microfilters are used to prevent entry of micro-organisms They remove particles of diameter 0.5µ or greater


STEAM STERILIZATION (AUTOCLAVING) Here saturated steam under pressure is used.

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Parts  Chamber (pressure vessel)–It is the portion of sterilizer in which the materials are placed & through which steam is circulated. Jacket - It is the portion surrounding the Chamber. It functions to maintain the temperature of chamber. The equipments are first cleaned & the packaged in muslin, linen or paper which are easily penetrated by steam & then placed on shelf in the chamber

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Phases  Conditioning/Heat Up Phase Air, if present, should be evacuated before sterilization, from the chamber as it reduces the amount of steam entering the Autoclave & hence the temperature achieved. Exposure/Sterilization phase As the steam enters the load, it gives Latent Heat to materials rapidly on contact. Microbial destruction will be most effective at these locations. Once intended temperature is reached, sterilization time is set.

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Principle  Water boils when its vapor pressure equals that of surrounding atmosphere. Thus when water is boiled in closed vessel at increased pressure, the temperature at which it boils & that of steam which is formed will exceed 100°C.

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When steam comes in contact with cooler surface  condenses to water & gives up its latent heat to that surface. Thus 1600ml of steam at 100°C & at atmospheric pressure condenses into 1ml of water at 100°C & releases 518calories of heat.

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TEMPERATURE (°C) PRESSURE (lb/in2) TIME (MIN) 121 15 15 126 20 10 134 30 3.5 150 50 Few Seconds

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It can also be carried out at Low Temperature & Low Pressure (LTS) i.e. at 37kPa with 74°C, but it won’t kill spores. The addition of vapor of formaldehyde to this is called as low pressure steam & formaldehyde (LTSF) which can kill many if not all spores. Ordinarily rubber goods, linens & metals are autoclaved. Post exposure/ Exhaust Phase. At the end the steam should be exhausted from the autoclave to avoid condensation of water on the load when cool air is admitted.

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Flash Sterilization Refers to steam sterilization of items for immediate use.

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Characteristics of Steam It should be optimum, otherwise efficacy will be decreased. It should be free from air, liquid or solid particles. For this, filters can be installed in the upstream of streamline.

Problems :

Problems Problems with the Steam Steam quality should be greater than 97%. Water, if present, results in wet steam. If the pressure is too high, it will cause the steam to rain & packs will become wet. If the pressure is too low, the steam will be superheated which is less able to transfer heat to items & it will be difficult to attain uniform temperature

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Air in Autoclave Chamber Air in the chamber will impair sterilization as it is poor conductor of heat & retards the penetration of steam. Efficacy of air removal process can be tested by Bowie-Dick test.

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Equipment Malfunction Equipment malfunctions like out-of-calibration temperature or pressure gauges, leaks, maladjusted control valves etc. Personnel Errors Personnel errors like inadequate cleaning, packaging methods, poor loading techniques etc.


Monitoring Mechanical Monitors : Devices that record time, temperature & pressure. Biological Indicators : they are standardized preparation of spores. A positive biological indicator is indicative of possible sterilization process failure. They should be used atleast once a week but time needed for incubation is long. E.g. spores of Bacillus Sterothermophilus .

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Chemical Indicators : these are more practical means & detect problems immediately. The CDC & all major U.S organizations standards & guidelines advocate that a chemical indicator be attached to every package that goes through a sterilization cycle & within each package to be sterilized in what is expected to be the most difficult-to-sterilize location. These are divided into 6 classes, higher the class, more sensitive the indicator.

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Class 1- These are Internal & External Process Indicator These inform that item has been exposed to sterilization process. E.g. External Process Indicator – Autoclave Tape.

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Class 2- E.g. Bowie-Dick test for vacuum steam sterilizer. They only access Vacuum Pump efficiency & detect the presence of air leaks &/or gases in steam.

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Class 3- E.g. Temperature Tube. Contains chemicals that melts & sometimes changes color when the appropriate temp is attained. Class 4- Respond to one or more sterilization parameters. Contains Ink that changes color when exposed to correct combination of sterilization parameters.

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Class 5- Known as Integrating Indicators or Integrators Respond to all parameters of sterilization over a specified range of temperatures. Class 6- These are emulating indicators. These are designed to react to all critical parameters over a specified range of sterilization cycles for which the stated values are based on the settings of the selected sterilization cycles

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Advantages Can kill all bacteria, spores & viruses. Rapid sterilization. Ease of use. Good penetration Economical. Absence of toxic products/ residues. Materials can be prepackaged & kept sterile until use.

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Disadvantages Heat sensitive materials are damaged like plastic & rubber goods. Cause blunting of cutting edges, crossing of metal surfaces. Oil, grease, powders are not sterilized because of lack of penetration. Shortened life of electronic components.



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Articles are packed in special craft papers and then placed in a thermostatically controlled Dry Heat Sterilizer. Precaution  temperature is raised and lowered slowly to prevent breakage by uneven expansion. Mainly suitable for ophthalmic instruments and glass items but not plastics or rubber. It is useful for sterilization of powders, grease, oil and glass syringes.

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Holding Temperature (°C) Time Of Sterilization (min) 180 30 170 60 160 120 150 150


CHEMICAL (COLD) STERILIZATION Utilizes liquid chemical agents Especially useful for heat sensitive equipment. Performed by soaking item in the solution. Kill the organisms by coagulation / alkylation of proteins and also by enzymatic degradation and lysis of cell membranes.

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The criteria to be satisfied in the Chemical Methods are Must be capable of killing spores. Should be non-corrosive Should be Non-irritant. Should be Economical. Should be stable Should penetrate grease & fibers. Should be non-toxic.

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Factors Influencing Chemical Sterilization: Concentration of the Chemical: Rate of kill of bacteria varies directly with the concentration of the disinfectant. b) Temperature: Designed to be used at room temperature.

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c) Evaporation and light deactivation: Volatile agents evaporate easily. Exp: Chlorine Products. Exposure to light adversely affects the disinfectant. d) PH: Alcohols work best in alkaline PH while aldehydes work best in acidic PH. e) Bioburden: The effectiveness of the disinfectant depends on the nature and number of contaminating microorganisms

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f) Characteristics of the item to be sterilized: A disinfectant solution will be effective only if it can contact all the surfaces on the item. g) Time: Time required for different chemical agents to function effectively varies from seconds to hours. h) Use Pattern, Use Life & Storage Life: Use Pattern refers to how many times the solution can be used. Use Life indicates limited period of time during which activated solution can be used. Storage life is the time period after which the unused or inactivated product is no longer deemed effective.


FORMALDEHYDE: Used principally in water based solution called formalin. Vapor can be generated from paraformaldehyde tablets which contain 95% formaldehyde in a polymerized form. It is a high level disinfectant. It is non corrosive and is not inactivated by organic matter. Widely used for sterilization of endoscopic equipment, catheters etc.

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For better effect it needs relative humidity of 60-80% and temperature of 37°C. Residual formaldehyde may affect the skin, but it can be neutralized by ammonia. Limited by its pungent odor and fumes. Should be handled as a potent sensitizer and probable carcinogen.


QUATERNARY AMMONIUM COMPOUNDS (QUATS) Low level disinfectants They are bactericidal, fungicidal & viricidal but not sporicidal. They are effective against gram positive than gram negative and marginally effective against Pseudomonas. They inactivate HIV but not hepatitis virus. They are inactivated by organic materials. Side effects are allergic reactions and contact dermatitis.


PHENOLIC COMPOUNDS They are intermediate to low level disinfectants. Derived from carbolic acid (phenol), one of the oldest germicides. They are bactericidal, fungicidal and viricidal but not sporicidal. They are active in the presence of organic matter. They are irritant to skin & mucous membranes, have bad odour . They are absorbed by rubber and residual disinfectant may cause tissue irritation.


ALCOHOL Intermediate level disinfectants. Ethyl alcohol is bactericidal in 60-90% concentration and isopropyl alcohol in 60% concentration. They kill bacteria but not spores, action against viruses is variable. CDC recommends exposure to 70% ethanol for 15mins to inactivate the hepatitis virus but 1 min for HIV . Their effectiveness is limited because of rapid evaporation, lack of ability to penetrate organic matter.

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They are used mainly to disinfect external surfaces of equipment like stethoscopes, ventilators, fiberoptic cables. They can damage mounting of lensed instruments and tend to swell and harden rubber.

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Chlorhexidine ( Savlon ) : It is a non detergent chemical disinfectant usually used in the concentration of 0.5% in 70% alcohol for skin. Tubes, masks etc. are sterilized by keeping for 20 min in 0.1% aqueous solution. Chloroxylenol ( Dettol ) : It is used as mild antiseptic agent


IODOPHORS It is a combination of iodine and carrier with a resulting complex providing sustained release reservoir of iodine. They are bactericidal, viricidal and tuberculocidal but not sporicidal. These are intermediate to low leve l disinfectants. They corrode the metallic items and non-metallic items may be stained or discolored.


PERACETIC (PEROXYACETIC) ACID It is acetic acid with an extra oxygen atom. It is bacteriocidal , sporicidal, fungicidal and viricidal. They are effective in the presence of organic matter. But it is corrosive and irritating to skin in concentrated solution. It is active ingredient in the steris sterilant. This is a single use concentrate of 35% peracetic acid + corrosion and degradation inhibitors.

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Used in wide variety of heat sensitive and delicate instruments. Used on wet or dry items and there is no personnel exposure. It can be situated in the Operating room suite. It is useful only for totally immercible objects and only small number instruments can be processed in a cycle.


CHLORINE AND CHLORINE PRODUCTS They are intermediate level disinfectants. They are active against bacteria and viruses but not spores. They are available both in liquid (sodium hypochlorite) and solid (Calcium hypochlorite) forms. They are most widely used, inexpensive and fast acting.

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Highly effective against HIV. Household bleach is an inexpensive and excellent source of sodium hypochlorite. A 1:100 to 1:1000 dilution is effective against HIV. 1 : 5 to 1:10 dilution is effective against hepatitis. It also inactivates Cruetz Feldt Jakob disease with an exposure time of 1 hr .

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Their use is limited by their corrosiveness, inactivation by organic matter and may leave residue which causes irritation to skin, eye and respiratory tract Potential hazard is the production of carcinogen bis-chloromethyl ether , when hypochlorite solutions come into contact with formaldehyde. A mixture of hypochlorite with acid will cause rapid evolution of toxic chlorine gas.

Hydrogen peroxide:

Hydrogen peroxide It is an effective bactericidal, fungicidal, viricidal and sporicidal. It is commercially available as 3% solution but can be used upto 25% concentration. It is non corrosive and not inactivated by organic matter but irritant to skin and eyes.

Glutaraldehyde (cidex):

Glutaraldehyde (cidex) It is a saturated dialdehyde. It is used in 1.0% concentration (but highly effective in 2% concentration). It is high level disinfectant . It kills spores within 12 hrs and viruses within 10 min. Widely used because of their excellent biocidal properties, activity in the presence of organic matter, non corrosiveness and noncoagulation of proteinaceous material.

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Disadvantages : It is noxious and irritating to tissues and hence thorough rinsing of all exposed materials is mandatory. Prepackaging is not possible and equipment will be wet. Pseudo-membranous laryngitis has been linked to disinfection of tracheal tubes with glutaraldehyde.

Ozone: :

Ozone: Sterilizers use O 2 , water & electricity to produce Ozone. Advantages: Useful for most goods that need low temperature sterilization. Process is environmentally friendly. Treated objects are dry. Disadvantages: Not approved for flexible scopes & reactive materials such as copper & brass. Unsuitable for natural gum rubber products

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Advantages of Chemical Sterilization Technically easier. Suitable for equipments damaged by heat sterilization. Sophisticated chemical methods like Ethylene Oxide achieve perfect sterilization. Disadvantages : Act only on exposed surfaces Some chemicals react with metals. Some impregnate with the materials such as rubber & plastics & some agents destroy it. Residual chemicals may form the source of infection.

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Disinfectant Gm + ve Bacteria Gm – ve Bacteria Tubercle bacillus Spores Viruses Fungi Formaldehyde + + + - + QUATS + + - - + + Phenolic compounds + + +/- - + + Alcohol + + + - + + Chlorine + + + - + + Hydrogen Peroxide + + + +/- + + Glutaraldehyde + + + +/- + +

Gas sterilization:

Gas sterilization EO is used for this purpose. It is a liquid below 11°C. It is available in high pressure tanks, unit dose ampoules and cartridges.

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1. Preparation for ethylene oxide (EO) sterilization (propylene oxide): Before packaging, items must be disassembled, cleaned and dried to allow the gas to penetrate throughout the whole product. Caps, plugs, valves, stylets must be removed. Hollow bore products and needles should be open at both ends. They should be towel or air dried.

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A relative humidity of 35% to 70% and a temperature of 18 to 22°C are recommended. Items to be sterilized are placed in carries that do not absorb E.O. They should be loaded loosely to allow for uniform penetration of gas throughout the load.

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Factors affecting EO Sterilization : Gas concentration : The solubility of EO in the product and the gas diffusion rate through the product will influence the sterilant concentration. Temperature : Exposure time can be decreased by increasing the temperature. Humidity : Moisture hydrates microbes, making then susceptible to destruction by EO.

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Protective barriers : Blood and other proteinaceous materials can act as barriers to EO. Packaging : The wrapping must be permeable to EO gas and water vapor and allow for proper aeration. Exposure time : Depends on factors mentioned above, generally range from 1.5 to 6 hrs. or many require upto 12 hrs

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3. Sterilizers: EO sterilizers are of two types, general purpose and special purpose .

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4. Indicators: Physical, chemical or biological indicators can be used but combination is better. CDC recommends the use of biological indicators at least once a weak.

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5. Aeration: EO not only comes in contact with all surfaces of articles being sterilized but also penetrates some items, which then retain varying amounts. Aeration may be done passively in air i.e ambient aeration or actively in a mechanical aerator.

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Factors affecting aeration: Metal and glass items do not absorb EO and require little or no aeration. Plastics, rubber, cloth, paper and muslin may absorb significant quantities. The most common material retaining large amounts of EO is PVC. Rubber absorbs little, polyethylene and nylon absorb still less. Diluent , gas mixtures with a fluorocarbon require longer aeration time than those diluted with C0 2 .

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6. Complications of EO sterilization : Patient complications  skin reactions, laryngotracheal inflammation, anaphylaxis, when blood comes in contact with EO sterilized items, destruction of red cells can occur. These are mainly due to by products Ethylene Glycol -formed by the reaction of EO and water. Ethylene Chlorhydrin - formed when EO comes in contact with chloride ions that may be present in previously γ-irradiated PVC items.

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Personnel complications : Acute exposure may cause URTI, eye irritation, headache, blunting of taste and smell, coughing. With higher concentrations  nausea, vomiting diarrhoea , fatigability, memory loss, drowsiness, incoordination , shortness of breath, convulsions have been reported. Respiratory paralysis and peripheral nerve damage may be delayed for 6 hrs or more after exposure. Chronic exposure can cause corneal burns, cataracts, epithelial keratitis, sensorimotor polyneuropathy, anemia. EO may be mutagenic or carcinogenic.

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Advantages: It is effective against all organisms: Damage to most equipment is minimal. Items can be prepackaged. Used for sterilization of delicate instruments like pump oxygenators, valves, ventilators etc. Disadvantages: More expensive Fire and explosions have been reported. Long duration. Personnel need to be highly trained and supervised.


RADIATION STERILIZATION Mainly used for disposable products. Gamma radiation is an electromagnetic wave produced during the disintegration of certain radioactive elements like cobalt-60. All organisms including spores, viruses will be killed. Lethal dose is 2.5 megarads(kills bacteria by ionizing there DNA). The products can be prepackaged.

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As there is no temperature rise, thermolabile materials can be sterilized. Equipments may be used immediately after treatment, with no risk from retained radioactivity. Disadvantage is that it is not practical for every day use and it is expensive.


GAS PLASMA STERILIZATION It uses a gaseous chemical germicide ( peracetic acid, hydrogen peroxide) and gaseous plasma.

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Advantages It is an effective sterilant for a variety of medical devices. It offers rapid low-temperature sterilization. Does not have environmental problems associated with EO. No personnel protection equipment are needed.


INFRARED RADIATION This is method of sterilization by dry heat usually used to sterilize the syringes and small instruments


ULTRAVIOLET RADIATION It is done by submitting the whole operation area to the light but the staff has to be protected from sun burn


STERRAD SYSTEM In this system, hydrogen peroxide is the precursor of active species of plasma. Total processing time is about 1 hr. It can be used for most items with exception of celluloric materials e.g. cotton, powders, liquid and devices containing dead end lumens. It is well suited to heat and moisture sensitive instruments since temperature does not exceed 50°C and sterilization occurs in low moisture environments.

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Advantages- These are small capacity systems. No venting or special installation is required. The process requires no aeration and There are no toxic residues


PLASMALYTE SYSTEM In this system the gas plasma is produced in a separate plasma chamber where the gas mixture of H 2 , O 2 and Argon is exposed to microwave electromagnetic field. Sterilization is carried out at / below 55°C. The duration of entire cycle varies from 3/ 2 to 4 hrs. It can be used for any item, but not recommended for liquids, powders, flexible endoscopes.

CDC rationale for Cleaning, Disinfection and Sterilization:

CDC rationale for Cleaning, Disinfection and Sterilization CDC has published guidelines on how to prevent or control specific nosocomial infection problems. They have divided items into three categories, based on the potential risk of infection involved in their use.

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Critical items : Are those that penetrate the skin and mucous membranes or are in contact with normally sterile areas of the body. These include vascular needles and catheters and regional block needles.

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2) Semicritical items : These are the items that come in contact with intact mucous membranes but do not ordinarily penetrate body surfaces. Sterilization is desirable, if not possible, a high levels of decontamination is acceptable. Ex : Endoscopes, laryngoscope blades, temperature probes, facemasks, airways, resuscitation bags, breathing lubes and connectors. ETT, double lumen tubes.

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3) Non critical items: Are those that do not ordinarily touch the patient or only touch the skin intact. Since intact skin normally acts as an effective barrier to most organisms, these items need only intermediate to low level of disinfection. E.g . Cables , CO 2 absorber, assemblies , exterior of anaesthesia machine, ventilators , humidifiers , monitors etc.



Anaesthesia Carts & Machines :

Anaesthesia Carts & Machines Top surface should be cleaned of visible material between cases. Disinfected with germicide at end of day

Gas Cylinders :

Gas Cylinders Washed with water & detergent. Then wiped or sprayed with germicide

Unidirectional valves, APL valves & Water Traps :

Unidirectional valves, APL valves & Water Traps Cleaned & disinfected periodically. They are disassembled & cleaned by wiping disc. The inside of the plastic dome & the valve seat with alcohol or detergent. Some APL valves may be autoclaved & some may be Pasteurized.

Tracheal tubes, Suction Catheters, Airways:

Tracheal tubes, Suction Catheters, Airways Washed with soap & water & rinsed. A malleable brush may be used to clean the inner aspect of tubes & airways. Boiling will sterilize it but tubes will be softened. Chlorhexidine 0.1% solution can be used. Here equipments should be soaked for 30-60min for complete sterilization. Autoclaving will be effective. But ETT should be replaced after 6 uses. Gamma radiation is satisfactory.

Face masks :

Face masks Rinsed, soaked & scrubbed after use. Wash with soap & water & thoroughly dried. Keep in water at 60-70°C for 20min. this reduces number of pathogens to very small no. Gas sterilization is v.effective method. It should not be boiled as boiling deteriorates masks

Laryngoscope Blades :

Laryngoscope Blades Boiled or Autoclaved after cleaning, but they may spoil electric connections. Carbolic acid 1-20% for 30min. can be used. Formalin oven can be used. Wiping with 70% alcohol or 0.1% Chlorhexidine in 70%alcohol is useful.

Breathing tubes & Reservoir bags :

Breathing tubes & Reservoir bags Wash thoroughly, rinse & allow it to dry in air. Repeated boiling spoils the antistatic properties, so it can be boiled once a week for 10min. Can be Pasteurized at 75°C for 10min. Chemical disinfection with glutaraldehyde for 1hr can be carried out by using automatic washing machine or by immersion. Tube should be inserted vertically during procedure


Y-piece Chemical disinfection. Ethylene oxide or Plasma sterilization can be used. It can be soaked in solution of water & detergent, then scrubbed manually or placed in washing machine.

Mapleson System :

Mapleson System Should be disassembled & component cleaned Metal components can undergo Autoclaving. Rubber & Plastic parts can undergo Gas or Plasma Sterilization.

Adaptors :

Adaptors Rinsed & soaked in solution of detergent & water. May be washed manually or in washing machine. Rubber & plastic adaptors- sterilized with EO, plasma sterilization or in Glutaraldehyde. Metal adaptors may be autoclaved or Pasteurized.

Water`s canister :

Water`s canister Can be washed & boiled. Can be Steam Autoclaved. Can be sterilized using Ethylene Oxide.

Circle Absorber :

Circle Absorber Gamma radiation Ethylene oxide. Formalin chamber. Can be dismantled & disinfected with spirit. Entry of organisms, while in use, can be prevented by using filters.

Ventilators :

Ventilators Bacterial filters Ethylene oxide Internal irrigation with antiseptics, provided the circuit is water tight. Ultrasonic nebulization with alcohol, hydrogen peroxide. Some have breathing units which can be autoclaved. Formalin Chambers can be used.


Humidifiers Pasteurized at 60°C. copper sponges may be used during this process as it has antibacterial effect. Frequent & thorough washing may be effective

Syringes & needles:

Syringes & needles Disposable syringes & needles are ideally gamma irradiated. Glass syringes are ideally autoclaved. In case of emergency, boiled in distilled water for 5min.

Instruments for local blocks:

Instruments for local blocks Lignocaine & Bupivacaine syringes, ampoules can stand Autoclaving at 160°C for 20min at 20psi. Repeated Autoclaving is avoided. Adrenaline ampoules should be autoclaved only once. Disposable sets are gamma irradiated.

Blood pressure cuffs, Tubing's & Stethoscopes :

Blood pressure cuffs, Tubing's & Stethoscopes Washed & dried thoroughly. Then subjected to chemical disinfection or Gas Sterilization. Nonfabric cuffs – plasma Sterilization is used. Stethoscopes can be washed with water & wiped with alcohol.

Pulse oximeter probes & cables :

Pulse oximeter probes & cables Cleaned by wiping with alcohol. Cables – Plasma sterilization



Special concern in open case of Pulmonary Tuberculosis.:

Special concern in open case of Pulmonary Tuberculosis. Endotracheal tubes & suction catheters are disposed off. If it is to be reused then keep in 0.1%Chlorhexidine solution for 1hr, then it is cleaned & scraped with soap & water & then sterilized by boiling or autoclaving. Boiling for 3min will kill tubercle bacilli. It can also be immersed in 2%Glutaraldehyde solution for 1hr.

Special concern in Hepatitis B positive cases:

Special concern in Hepatitis B positive cases The virus is killed by Autoclaving & Gamma Radiation. Chemical sterilization- Sodium Hypochlorite 50ppm, Glutaraldehyde 2% for 10 min. Iodophor 80ppm Isopropyl alcohol 70% for 15 min.

Special concern in HIV cases:

Special concern in HIV cases The virus is relatively unstable in environment & can easily be inactivated by wide range of Chemical Disinfectants like- Glutaraldehyde 2% for 10 min. Sodium Hypochlorite 50ppm. Hydrogen peroxide 0.3%. Ethyl alcohol 50%, Isopropyl alcohol 70% for 1 min. Phenol.

Special concern in Prion Diseases:

Special concern in Prion Diseases It is extremely resistant to normal Sterilization methods. For Critical Devices – Steam Sterilization for 30min at 132°C is recommended. For Non-Critical Devices- Sodium Hypochlorite, undiluted or 1:10 dilution is used. 1N sodium hydroxide at room temperature for 15min can also be used.

Operation theatre cleaning and fumigation:

Operation theatre cleaning and fumigation

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Cleaning programme should be simple and clearly laid out policy which can be adhered to. Daily cleaning should be carried out after the operating sessions are over. All the surfaces should be cleaned with detergent and water and may be wiped over with a phenol if any spills with blood / body fluid are present. All the walls must be wiped down to hand height everyday.

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The floors should be scrubbed with warm water and detergent and dried. No disinfectant is necessary. The O.T. table and other non clinical equipments must be wiped to remove all visible dirt and left to dry. Weakly cleaning of all the areas inside the operating theatre complex should be done thoroughly with warm water and detergent and dried. The storage shelves must be emptied and wiped over, allowed to dry and restacked.

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Procedure for fumigation: The windows should be sealed and formaldehyde should be generated either by boiling a solution of formalin 40% or by adding it to potassium permanganate, in a metal vessel on the floor, since heat is also generated. The door is than closed and scaled. For a 10 x 10 x 10 ft room - 150 gm potassium permanganate and 280 ml of formalin are used

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Duration: In case of any construction in O.T.  48 hrs In case of inflected cases  24hr For routine clean cases  12 hrs. Alternatively 250 ml of formalin and 3000 ml of tap water are put into a machine (auto mist) and time is set for 2 hrs. The mist is circulated for 2hrs inside the closed room.

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Room is kept sealed for another 2 hrs for action of vapor. Ventilate for suitable time for vapor to dissipate. Room then can be used. Three swabs are taken from walls, all equipments, floor or O.T. table at intervals. 1 st swab - 48 hrs after fumigation 2 nd swab- 24 hrs after I s ' swab 3 rd swab - 12 hrs after 2" d swab

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All three consecutive swabs should come negative. In some centres , Bacillocid is being used for fumigation. It is combination of chemically bound formaldehyde and glutaraldehyde. Ideally all O.T. rooms should be fumigated once a week


REFERENCES Understanding Anesthesia Equipments- Dorsch & Dorsch . Anaesthesia Equipments- Wards. ISACON 2006, 2007. Textbook Of Anaesthesiology- Sathish Deshpande

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