Theme 10 - Sterilisation Flashcards
How have antiseptics evolved?
- 3000 BC used pitch and tar - Egyptians used resins for embalming
- 1881 Koch devised first non pressure steam steriliser
- late 1800s surgical instruments design changed as antiseptic and aseptic techniques normal now
- 1968 - Earle Spaulding made reccomendations about disinfection and sterilising instruments according to use
- 1994 William Rutala worked with CDC to characterise and idea method of sterilisation
Earle Spaulding’s 3 classifications of instruments and equipment
- critical
- semi critical
- non critical
What is a critical instrument?
- penetrates mucous membranes or has contact with blood/saliva, bone and high risk of infection
What is a semi critical instrument?
- contacts with mucous membranes
- doesn’t penetrate soft tissues
What is a non-criticial instrument?
one that undergoes manual cleaning disinfection
Define ‘decontamination’
the process of rendering an object or area free of danger from contaminants
Define ‘disinfection’
- process of killing or removing most but not all viable organisms
Define ‘sterilisation’
- saturated steam under pressure delivered at highest temp
- eliminates or kills all forms of life including transmissable agents such as viruses, bacteria and spores
Chemical methods of disinfection
- liquids like alcohols, aldehydes, phenolic, halogens, surface active agent, dyes
What is needed from disinfectant?
- kills microorganisms on inanimate object/surfaces
- inhibits growth/ germination of pathogenic microorganism
- fast acting even with bodily fluids
- easy to prepare and stable in light and heat
- easily penetrated without discolouring/damage
- inexpensive
- no unpleasant odour
What do we use for surface disinfection?
What is disinfected?
- wipe sprays - acticohl solution (1:1000)
- chairs, lights, brakcet tables, spittoons, work surfaces, X-ray units, light curing units
Why is the light curing unit disinfected not sterilised?
- too sensitive or large to sterilize
What is used for skin disinfection?
- antiseptics anti microbial
- hand washing
- chlorhexidine mouth wash before surgery
- cleaning root canals, dry sockets
Explain immersion
- liquid disinfectant
- 3-30 minutes
- for impressions, removable restorations like dentures, crowns
- washer disinfector pre sterilization
2 methods of sterilization
- physical
- chemical
Explain physical sterilization
- sunlight
- heat (dry heat, incineration, flaming, hot air OR moist heat autoclave)
- radiation
Explain chemical sterilization
- liquid - formaldehyde or glutaraldehyde
Uses of dry heat - hot air oven
- pre-packed sterile materials sensitive to moisture
- like cotton wool rolls, gauze, paper points, surgical instruments
Cycle of dry heat - hot air oven
- 121 degrees for 6 hrs
- 160 degrees for 2 hrs
- 171 degrees for 1 hr
How is the autoclave so effective?
- moist heat
- in the form of pressurised steam it’s the most reliable method of killing all bacterial life
- penetrates materials more rapidly than dry heat
Types of autoclave
- type N - downward pressure
- Type S - vacuum
- type B - vacuum
Uses of autoclave
- unwrapped items
- solid and hollow items
- porous loads like gowns and drapes
Cycles of autoclave
- 121 degrees for 15 mins
- 134 degrees for 3 mins
- 30 mins total
How does the autoclave cycle work?
- water boils and the vapour pressure equals that of surrounding atmosphere
- pressure of gas increases in enclosed vessel, temp increases too
- increase in temp causes water molecules in steam to become more energized
- saturated steam can penetrate materials (agent is the moist heat not the pressure)
- when steam contacts cooler surfaces it condenses to water and gives up latent heat to it
- reduction in steam sucks more steam into site and process continues until temp of objects is raised to temp of steam
Chemical sterilization is also called …
cold sterilization
How does chemical sterilization work?
- instruments immersed in glutaraldehyde solution
- up to 6hrs
2 types of radiation used
- non-ionising
- ionising
What is non-ionising radiation?
- low energy radiation
- produced by UV lamps
What is ionising radiation?
high energy, gamma rays, x-rays
Radiation sterilization is used in what?
industry for drugs and antibiotic sterilization
Decontamination cycle
- stores used
- picked up
- cleaned and sorted
- washer disinfector
- inspection and protein testing
- sorting and packing
- sterilization
- packed on trollies
What stages are added to sterilization of handpieces?
- stored
- cleaned
- washer disinfector
- packed
- sterilized
- SENT TO CURATOR
- cleaned
- washer disinfector
- packed
- RE-STERILIZED
