Sterilization of Anesthesia Equipment – Overview 🔹 Why Sterilization Is Essential Anesthesia equipment comes into direct contact with mucous membranes and sometimes enters sterile body areas. Contaminated equipment can lead to nosocomial infections, cross-contamination, and patient complications. 🔹 Classification of Anesthesia Equipment (Spaulding’s Classification) Critical Items – Enter sterile tissues (e.g., syringes, needles). Require sterilization. Semi-critical Items – Contact mucous membranes (e.g., laryngoscope blades, breathing circuits). Require high-level disinfection or sterilization. Non-critical Items – Contact only skin (e.g., BP cuffs). Require low-level disinfection. 🔹 Commonly Sterilized Anesthesia Items Laryngoscope blades Endotracheal tubes (ETTs) (if reusable) Breathing circuits Face masks Airway adjuncts (oropharyngeal/nasopharyngeal) Reusable syringes and metal parts of anesthesia machines Sterilization Methods 1. Autoclaving (Steam Sterilization) Temp: 121–134°C Time: 15–30 mins (depending on temp/pressure) Used for: Metal laryngoscope blades, reusable ETTs, anesthesia instruments. Not suitable for: Heat-sensitive equipment. 2. Chemical Sterilization (Cold Sterilization) Agents: Glutaraldehyde (2%), Peracetic acid, and Hydrogen peroxide. Immersion time: 10–12 hours (for sterilization) Used for: Heat-sensitive plastic items. Precaution: Rinse thoroughly after use. 3. Ethylene Oxide (EtO) Gas Sterilization Used for: Complex, heat- and moisture-sensitive items (e.g., flexible bronchoscopes). Cycle time: 6–12 hours + aeration time. Effective but expensive. 4. Plasma Sterilization (Hydrogen Peroxide Gas Plasma) Low temperature (50–55°C) Quick cycle (~1 hour) Used for: Fiberoptic scopes, delicate electronics. 5. Boiling (Disinfection, not sterilization) 100°C for 20 minutes Kills many but not all spores Used for low-resource settings Cleaning Before Sterilization Manual cleaning with detergent/enzyme solution to remove organic debris. Use ultrasonic cleaners for fine instruments. Dry completely before sterilizing. 🔹 Disinfection (For Semi-critical items if sterilization not possible) High-level disinfection using chemical agents (e.g., glutaraldehyde). Items must be soaked as per the manufacturer’s instructions. 🔹 Storage After Sterilization Store in sterile packaging. Label with sterilization date and expiry. Check for integrity of packaging before use. 🔹 Documentation & Quality Control Sterilization logs should be maintained. Indicators: Chemical Indicators (color change strips). Biological Indicators (Bacillus spores). Regular checks ensure sterilizer function and compliance. Summary Table: Method Temp/Agent Used For Advantage Autoclave 121–134°C steam metal instruments Fast, reliable Chemical Glutaraldehyde, etc. Heat-sensitive items Good for plastic items EtO Gas Ethylene Oxide complex, heat-sensitive devices Penetrates deep Plasma (Sterrad) Hydrogen Peroxide Fiberoptic equipme

1. STERILIZATION OF ANAESTHESIA
EQUIPMENT
MODERTATOR’S: Dr.T.Suryasree mam
(HOD ,Dept of Anaesthesiology).
Dr.Bharathi mam(ASSISTANT PROFESSOR)
SPEAKER:Dr.Sumalatha(2nd
yr PG)

2. INTRODUCTION
• Anaesthetic equipment is exposed to microorganisms
from multiple sources during routine use
• Proper infection control procedures are essential to
minimize risk of transmission of hospital care associated
infection
• All used equipment should be considered contaminated
& appropriately disinfected prior to reuse
• Increasing trend towards use of disposable or single use
equipment

3. DEFINITION
 Disinfectant :Chemical germicide formulated to be used on
inanimate objects. The EPA classified them as with or without
tuberculocidal activity.
 Mechanical indicators[Physical indicator/monitor]: Sterilizer
component that records time , temperature, humidity or
pressure during sterilization cycle.
 Sterilization: Process capable of removing or destroying all viable
forms of microbial life, including bacterial spores ,to an
acceptable sterility assurance level.
 Sterility assurance level[SAL]: Probability that microorganisms
will survive after a terminal sterilization process.SAL of 10⁻⁶
indicates sterile item.

4. Levels of Disinfection

5. Order of resistance of organisms
prions
bacterial spores ( bacillus,clostridium)
mycobacteria ( bovis ,tuberculosis)
non lipid or small viruses (polio, rhino )
fungi
vegetative bacteria(pseudo,staph,salm)
lipid or medium sized viruses(hep.B,HIV.CMV,herp)
least resistant
Most resistant

6. In 1968 ,Spaulding classified the medical instruments

7. Critical equipment

8. Semicritical equipment

9. Non critical equipment

10. Stages in the processing of equipment
1.Cleaning and decontamination
• Then if required
2.Disinfection and sterilization

11. Cleaning
• First and most important step in decontamination
• Prevents spread of infection between patients
Objectives:
1. To reduce bio burden
2. To remove pyrogens, tissue fragments and organic deposits
which may be toxic to the pt and interfere with
decontamination
3. To prevent cumulative deterioration of equipment
4. To meet hygienic anaesthesia standards
• Water temp should not exceed 45°C ,because higher
temperatures causes proteinaceous soil to coagulate

12. • Aim→ to remove retained salt and organic soil which can
inactivate chemical germicides or protect the organisms
from destruction during disinfection or sterilization.
• Procedure→ Immersible items can be cleaned under
water, with or without detergent for atleast 3mins to
prevent aerosolization of organisms and those not
immersible can be cleaned with cloth soaked in
detergent and water.
• Stainless steel or other metal devices should not be
soaked in saline or sodium hypochlorite because the
chloride ions will cause the metals to corrode.

13. • Disassembly →Devises must be dismantled
• Initial soaking in a protein dissolving solution can prevent blood
coagulation on the device and removes gross debris
• later they should be thoroughly scrubbed inside and out.
• Instruments having joints , crevices , lumens can be cleaned by
ultrasonic cleaning after gross soil has been removed.
• In an ultrasonic cleaner, high frequency sound waves passing through
the solvent produces bubbles, which collapses on themselves ,
generating tiny shock waves, which removes the debris
• Ultrasonic cleaning tanks are available in variety of sizes, items are
placed in a tray into the tank for a preset of time usually 3-6 min
• After cleaning rinsing should be performed to remove soil and residual
detergent. Lumens and channels should be well flushed during each
rinse.
• Cleaned items should be towel or air dried.

14. Disinfection and Sterilization methods
Pasteurization:
• It is high level disinfection process
• It can't kill all spores and viruses, so it is recommended where
absolute sterility is not required.
• The equipment is immersed in water at an elevated temperature of
80°C for 10 minutes or 70°C for 30 minutes
• Used for breathing tubes, reservoir bags, tracheal tubes, face masks ,
airways, laryngoscope blades, stylets , bite blocks, Y-pieces, adaptors,
ventilator bellows.
• Advantage: Simple, inexpensive, reliable, no toxic fumes, lower
temperature is less damaging to equipment.
• Disadvantage: Sterilized equipment is wet and must still be dried and
packaged during which again it may be contaminated.

15. Steam Sterilization[Autoclaving]
• Utilizes saturated steam under pressure
• It is most widely used and inexpensive method of the
sterilization techniques.
• Principle →At sea level water boils at 100°c,when it is
boiled in a closed vessel at an increased pressure, the
temperature at which it boils and forms steam will
exceed 100°C, increase in the temperature depends on
the pressure within the chamber
• Pressure per se has no sterilizing effect
• It is the moist heat that brings about sterilization.

16. Autoclave/ steam sterilizer

17. Temperature[°c] Time[mins]
121 15
126 10
134 3.5
150 Few seconds
Increasing the temperature reduces time needed to achieve sterilization

18. Problems with steam sterilization
1. Problems with heat:
• steam is saturated when it has proper balance of pressure and
temperature
• If the pressure is too high, steam will change to liquid causing packs to
become wet
• If the pressure is too low ,the steam will be superheated, superheated
steam is less able to transfer its heat energy to the items being sterilized
& will interfere with achieving uniform temp in the chamber
2. Air in the autoclave chamber : will impair sterilization , air conducts heat
poorly and retards steam penetration
3. Equipment malfunction: out of calibration temperature & pressure
gauges , maladjusted control valves, leaks ,clogged vent lines
4.Personnel errors: inadequate cleaning, incorrect pack preparation

19. Steam sterilization monitoring
 Mechanical indicators : indicate time , temperature and pressure.
Most autoclaves provide permanent record of these parameters
 Biological indicators:
• they are standardized preparation of spores that are placed in
most difficult to sterilize locations in the load
• The indicators are exposed to the sterilization cycle,
retrieved ,incubated and examined for microbial growth
• Positive biological indicator is indicative of sterilization process
failure
• Main problem with biological indicators is the time needed for
incubation

20. Chemical indicators:
• Divided into 5 classes ,higher the class more
sensitive the indicator
Class description
1 Indicators are internal and external process indicators ,these inform the user that the
item has been exposed to sterilization process
Eg. For external process indicator is autoclave tape –visual proof
internal process indicators exhibit color change from white to black
2 Related to bowie dick test for vacuum steam sterilizers, do not determine if the
parameters have been met ,only assess vacuum pump efficiency and detect air leaks in
the steam
3 Indicators are single parameter eg. Temperature tube that contains a chemical that
melts and changes color when appropriate temp is attained
4 Indicators respond to one or more parameters, they contain an ink that changes color
when exposed to correct combination of sterilization parameters
5 Also known as integrating indicators or integrators. they respond to all parameters
over a specified range of temperature

21. Advantages of autoclaving:
• Reliability , speed , good penetration, economy , ease of use,
absence of toxic products or residues
• Material can be prepackaged and kept sterile until used
• No harm to the environment
• At least one autoclave is available in modern OT
Disadvantages
• Many pieces of equipment are damaged if subjected to steam
• Blunts the cutting edges , metal surface corrosion and
shortens the life of electronic components

22. Chemical[Cold] sterilization
• Utilizes liquid chemical agents
• Useful for heat sensitive equipment
performed by soaking the item in the solution.
• Kill the organisms by coagulation/alkylation of
proteins, enzymatic degradation and lysis of
cell membranes.

23. Criteria to be satisfied in the
chemical methods are
1.Must be capable of killing spores
2.Non corrosive
3.Non irritant
4.Economical
5.Stable
6.Penetrate grease and fibers
7.Non toxic

24. Factors influencing chemical disinfection
1. Concentration of the chemical : Rate of killing of bacteria
varies directly with the concentration of the disinfectant
2. Temperature : Higher temperatures increases the
effectiveness of the chemical agents.
3. Evaporation and light deactivation : Volatile agents
evaporate easily especially chlorine products, Exposure to
light deactivates.
4. pH: Alcohols work best in the alkaline pH while aldehydes
work best in the acidic pH.
5. Bioburden : Effectiveness of disinfectant depends on the
nature and number of the microorganisms.

25. 6.Characteristics of the items to be sterilized: A disinfectant
solution will be effective only if it can contact all surfaces
of the item.
7.Time: Time required for different chemical agents to
function effectively varies from seconds to hours.
8.Use pattern , Use life and 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 effective.

26. Glutaraldehyde[Cidex]
• It is a saturated dialdehyde used in 1% concentration
but highly effective in 2% concentration.
• High level disinfectant, kills spores within 3hours and
viruses within 10mins.
• Widely used because of excellent germicidal
properties ,activity in the presence of organic matter,
non corrosiveness and non coagulation of
proteinaceous material.
• It has extensive shelf life , can be used as long as
30days after activation.

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

28. Orthophthaldehyde(OPA or cidex
OPA)
• Achieve high level disinfection at room
temperature after a 12 min exposure period and
after a shorter time at an elevated temperature
• It is sporicidal with prolonged exposure
• Advantages : faster disinfection , minimal odour ,
no need for activation or mixing
• Side effects are less than Glutaraldehyde , eye
contact may cause excessive tearing and redness

29. Hydrogen peroxide:
• High level disinfection can be achieved in 30 min using 7.5%
solution
• Bactericidal, virucidal , sporicidal and fungicidal properties
• rapidly loses effectiveness when exposed to heat and light and
requires careful storage
• 3% solution is a low level disinfectant
• Used for plasma sterilization
Formaldehyde:
• Is a highly toxic and flammable gas that has been used as a
disinfectant in both liquid (formalin) and gaseous state
• Although formalin is a high level disinfectant, uses are limited by
pungent odor and fumes
• NIOSH indicated that formaldehyde is a potent sanitizer and
probable carcinogen

30. Chlorine compounds
• Intermediate level disinfectants
• Active against bacteria and viruses but not spores
• Available both in liquid ( sodium hypochlorite) and solid ( calcium
hypochlorite) forms
• Most widely used, inexpensive and fast acting
50 ppm-vegetative bacteria
100 ppm-fungi
200 ppm-more viruses including HIV
500 ppm for HBV
1000 ppm – high level disinfection
• 1:5 to 1:10 dilutions (5000 ppm ) will destroy CJD after an
exposure time of 1 hour

31. • Their use is limited by their
corrosiveness, inactivated
by organic matter and may
leave residue which may
cause irritation to skin ,
eye and respiratory tract
• Not often used for
instrument disinfection
but have been used for
environmental disinfection

32. Phenolic compounds:
• Are derived from carbolic acid,and one of the oldest germicides
• Intermediate to low level disinfectants
• Bad odor and irritating to skin
• Use is restricted to environmental surfaces and non critical
devices
Alcohols:
• Intermediate to low level disinfection
• bactericidal in 70-90% concentration
• CDC recommends exposure to 70% ethanol for 15 min to
inactivate HBV & 1 min to inactivate HIV

33. Quaternary ammonium compounds[QUATS]
• Low level disinfectants
• bactericidal,fungicidal,virucidal but not sporicidal.
• They are effective against gram positive than gram
negative and marginally effective against Pseudomonas.
• They inactivate HIV but not Hepatitis virus
• Ineffective against M.tuberculosis
• Inactivated by organic materials
• Side effects are allergic reactions and contact dermatitis.

34. Iodine compounds:
• An iodophor is a combination of iodine and a
solubilizing agent or carrier with the resulting complex
providing a sustained release reservoir of iodine
• Intermediate to low level disinfectant
• Bactericidal, virucidal and tuberculocidal but not
sporicidal
• They corrode the metallic items and non metallic
items may be stained or discolored

35. Peracetic acid (peroxyacetic acid ):
• It is an acetic acid with extra oxygen atom
• Bactericidal, sporicidal , fungicidal and virucidal
• It is effective in the presence of organic matter , but it is
irritant to skin
• It is active ingredient in Steris sterilant system, which
provides quick method of disinfection of heat sensitive
immersible instruments including fiberscopes
• Steris 20 is developed specifically for steris processors

36. Steris system
For safe & effective processing of reusable, heat sensitive
semi critical devices such as fibreoptic endoscopes ,
bronchoscopes & duodenoscopes

37. ozone
• Ozone sterilizers use O₂ ,water & electricity to produce
ozone
Advantages:
• Useful for instruments that need low temperature
sterilization
• The process is environmental friendly and no toxic residuals
Disadvantages:
• Not approved for flexible scopes& reactive metals such as
copper & brass
• Unsuitable for natural gum rubber products

38. Advantages of chemical sterilization:
• Economy, speed and simplicity
• Suitable for equipments damaged by heat sterilization
• Useful for equipment that does not require sterilization but
require high level disinfection.
Disadvantages
• Acts only on exposed surfaces
• Some chemicals react with metals
• Some impregnate with the materials such as rubber and plastics
and destroy it
• Residual chemicals may form the source of infection.

39. Gas or ethylene oxide sterilization
Characteristics of ethylene oxide
• Ethylene oxide [ EtO , EO] is a colorless ,poisonous gas
with a sweet odor.
• It is a liquid below 11°c.
• It is available in high pressure tanks, unit dose ampules
and cartridges
• It kills bacteria , fungi , spores and viruses.
• It penetrates into crevices and through permeable bags.
• It is not degraded by organic soil but will not penetrate
dried protein material

40. Preparation for ethylene oxide sterilization:
• Before packaging , items must be disassembled , cleaned and
dried to allow the gas to penetrate throughout the product.
• Caps , plugs, valves , stylets must be removed ,hollow bore
products such as needles and tubes must be opened at both
ends.
• Items must be free of water droplets ,they should be towel or
air dried.
• A relative humidity between 35% and 75% and a temperature
between 18°c and 22°c are recommended.
• Items to be sterilized are placed in wire baskets , metal carts
or other carriers that do not absorb EO.
• Items should be loaded loosely to allow the gas to penetrate
throughout the load.

41. Factors affecting EO sterilization:
• Gas concentration: Solubility of EO in the product and the gas
diffusion rate through the product will influence sterilant
concentration.
• Temperature: exposure time can be decreased by increasing the
temperature.
• Humidity: moisture hydrates microbes making them more
susceptible to destruction by EO.
• Productive barriers: blood and other proteinaceous materials can
act as barriers to EO.
• Packaging: the wrapping must be permeable to EO gas
• Exposure time: generally ranges between 1.5 and 6 hours.

42. Complications of EO sterilization
• Patient complications :due to failure to eliminate residual
gas from sterilized items include skin reactions , laryngo
tracheal inflammation , hemolysis
• Equipment alteration :rubber and some plastic tracheal
tubes may soften , kink more easily or become sticky
• Personnel complications: eye irritation, respiratory
infections ,anemia, impaired cognitive function, EO is a
recognized mutagen & carcinogen and adversely affect the
reproductive system. According to OSHA regulations
workers does not expose to time weighted average levels
above 0.5 ppm during 8 hours or 5 ppm during 15 min time

43. Advantages:
• Effective against all organisms
• Damage to equipment is minimal
• Items can be prepackaged
• Used for sterilization of delicate instruments like pump
oxygenators ,valves , ventilators.
Disadvantages:
• More expensive
• Long duration
• Fires and explosions
• Personnel need to be highly trained and supervised.

44. Radiation sterilization
• Mainly used for disposable products eg: surgical gloves, face
masks, gowns, syringes, plasters, sutures, dressings
• Gamma radiation is an electromagnetic wave produced
during the disintegration of certain radioactive elements like
Cobalt 60.
• All organisms including spores and viruses will be killed.
• Lethal dose is 2.5megarads
• Items can be prepackaged prior to sterilization
• Equipment can be used immediately after treatment with no
risk from retained radioactivity.
Disadvantage:
• Not practical for everyday use and expensive.

45. Gas plasma sterilization
• Gas plasma is sometimes described as the 4th
state of matter, consisting
of reactive ions , electrons , and neutral atomic & molecular particles
• The reactive species in the plasma interact with the molecules that are
essential for metabolism & reproduction of living cells
• Hydrogen peroxide vapor is most often used
Advantages
• Reliable, effective method , heat sensitive items can be sterilized
• Processing time is short
• No toxic residue so no risk to personnel
Disadvantages
• Small size of sterilization chamber
• Certain items eg: cellulose materials , powder , liquids& implants cannot
be sterilized

46. Special diseased states
Open TB case:
• ET tubes & suction catheters are disposed off
• If it is to be reused then keep in 0.1%
chlorhexidine solution for 1hr,then cleaned and
scraped with soap and water and sterilized by
boiling or autoclaving.
• Boiling for 3minutes will kill TB Bacilli , can also
be immersed in 2% glutaraldehyde for 1hr.

47. Hepatitis B positive case:
• Virus is killed by autoclaving and gamma
radiation
• Chemical sterilization-sodium hypochlorite 50
ppm.
• Glutaraldehyde 2% for 10minutes.
• Iodophor 80ppm
• Isopropyl alcohol 70% for 15minutes.

48. HIV positive case:
• The virus is relatively unstable in environment and
can easily be inactivated by wide range of
chemical disinfectants.
• Glutaraldehyde 2% for 10minutes
• Sodium hypochlorite 50ppm
• Hydrogen peroxide 0.3%
• Ethyl alcohol 50%,isopropyl alcohol 70% for
1minute.

49. Prion disease:
• it is extremely resistant to routine sterilization methods.
• Preferred treatment of contaminated instruments after cleaning is
steam sterilization for at least 30 min at 132°c .
• Alternatively items can be immersed in 1N sodium hydroxide
solution for 1hr at room temperature and then steam sterilized at
121°C for 30 min.
SARS:
• Viral disease transmitted by respiratory droplets or contact
• NIOSH approved N95 or greater respirator should be used when
contact with pts is necessary
• Goggles or face shield , disposable gown ,cap and double gloves
should be worn

51. THANK YOU