Sterilisation Flashcards
Spaulding classification of a critical device
a device that penetrates soft tissues, makes contact with bone and enters/contacts bloodstream or normally sterile tissue
reprocessing & egs of a critical device
device must be cleaned and then sterilised e.g. surgical & biopsy instruments, forceps
Spaulding classification of a semi-critical device
device that comes into contact with non-intact skin / mucous membrane but does not penetrate soft tissue or make contact with the bloodstream, bone or normally sterile tissue
reprocessing & egs of a semi-critical device
device must be cleaned and subject to high-level disinfection, steam sterilisation preferred e.g. dental mirrors, anaesthetic syringes
Spaulding classification of non-critical device
device that only comes into contact with the skin and intact mucous membrane
reprocessing & egs of non-critical device
cleaning follow by low level disinfection e.g. chair light handle
describe cycle for processing instruments (9)
- cleaning
- disinfection
- inspection - disposal; either scrap or return to lender
- packaging
- sterilisation
- transport
- storage
- use
- transport
what is the first step in processing cycle
cleaning - to remove biological matter from surface of instruments
why must instruments be cleaned at the 1st stage (5)
- functionality of instrumentation
- to minimise spread of contamination
- to prevent failed procedures (biopsy)
- to achieve steam contact
- legal requirement
what is the recommended cleaning method and what should be used if this is not available
recommended = washer-disinfector
back up is ultrasonic bath
manual cleaning should only be carried out if only option available
what happens after all visible contamination has been removed
processed through steam steriliser (can use vacuum or non vacuum machines)
what machines are used for steam sterilisation and which is best
type B - vacuum
type N - non vacuum
vacuum is better
PPE required for manual cleaning
apron
visor
rubber gloves
heavy duty rubber gloves
water must be what temperature for manual cleaning and why
30-35 degrees; anything more than this can cause proteins to coagulate making them more difficult to remove
2 different methods of manual cleaning
immersion
non-immersion
what kind of brush should be used in manual cleaning
long handled, soft bristled brush
why scrub below the surface of the water
- instruments must be in contact with water and detergent solution
- essential to minimise splashing which will contaminate surroundings
- scrubbing above the surface has the potential to produce aerosols
when should manual cleaning be carried out
- if specifically recommended by manufacturer’s instructions for processing
- if there is no other alternative i.e. all automated equipment is out of service
- the automated process of the ultrasonic or WD has failed to remove contamination
describe the cavitation process in the ultrasonic
fluctuation in pressures the sound waves induce cause the bubbles to rapidly expand and then collapse
what is the operating temp for the ultrasonic bath
20-30 degrees
how to run the ultrasonic bath
machine filled with tap water to required volume
chemical added based upon MI
cycle ran for specific period of time established at validation
what must happen the ultrasonic bath before any cycles are run
a degas cycle - chamber filled with water and detergent & ran.
this is to remove air bubbles which could affect the efficacy of the equipment and prevent proper cleaning
following manual / ultrasonic cleaning what happens instruments
they must be rinsed
what happens after rinsing
thermally disinfected again in the washer-disinfector
reasons for manual / ultrasonic cleaning
- manually scrubbing with brush exerts a greater force than the WD can produce
- some equipment must only be manually washed in line with manufacturer’s instructions
- ultrasonic baths good at removing contamination
reasons against manual / ultrasonic cleaning (7)
- member of staff required to be present for entire process
- risk of aerosol production
- risk of contaminating surrounding environment
- potential for inconsistency in process to human error
- high risk of sharps injuries for staff involved
- ultrasonic can potentially damage equipment
- no automatic water changes in ultrasonic bath
name the stages of the WD
- flush/pre wash
- main wash
- rinse
- thermal disinfection
- drying
describe the stages of WD
- flush - saturates contamination and removes gross contamination
- main wash - supplemented by detergent to more efficiently remove biological matter
- rinse - removes remaining residue, biological or chemical before disinfection
- thermal disinfection - actively kills microorganisms with use of heated water
- drying - uses hot air to remove remaining moisture from surface of instruments
what temperatures are used at each stage in the WD
- flush - <35 degrees
- main wash - temp dependent on chemical used
- rinse - <65 degrees
- thermal disinfection - 90-95 degrees for 1min minimum
- drying - usually 100 degrees
why is the WD the first step in the decontamination process (4)
- fresh water at each stage
- thermal disinfection makes instrumentation safe for staff to handle
- consistency - machine process is virtually the same every time
- traceability - automated processes produce a printable record of each cycle
daily checks for WD (6)
- check spray arms spin freely without obstruction
- check spray jets are not blocked
- make sure no debris on strainer/filter
- check condition of door seal, wipe & clean if necessary
- verify suitable amount of chemical in reservoir
- record disinfection temp of 1st cycle every day (known as ACT)
what happens after WD
inspect instruments but if still contaminated then process through ultrasonic bath / manually clean then they are reprocessed through the WD before sterilisation
what water is used for steam for sterilisation
purified water i.e. de-ionised/distilled/sterile/reverse osmosis
3 main types of steriliser used
- type N
- type B
- type S
what is type N
most basic process of sterilisers
known as gravity displacement steriliser / autoclave
what is type B
most robust processing cycle
known as vacuum capable / porous load steriliser
what is type S
specialised used for specific purpose e.g. sterilising hand pieces
describe type N steriliser
machine heats water in chamber
as it turns to steam it passively forces air from chamber
process not efficient as can leave pockets of air
not favourable for high quality sterilisation process
cannot process wrapped instruments or channelled / lumened either
not sterile at point of use
what temp & pressure required for type N
134-137 degrees
2.05 - 2.35 is the corresponding pressure
must maintain this for minimum of 3 mins
describe type B steriliser
remove all air out of chamber then it fills with steam
as air removed first, vacuum has been created
this allows steam to rush into chamber so it effectively contacts all surfaces
has capability to penetrate wrapping of instruments
will be sterile at point of use
temp & pressure of type B
134-137 degrees
2.05-2.35 corresponding pressure
hold at minimum time of 3 mins
daily test on type B
steam penetration test using bowie dick test pack or a helix
weekly test on type B
air leakage test
air detector function test (ADFT)
common daily checks for type N & B
check door seals are intact & free from debris
verify chamber is free from damage debris contamination & instruments from other cycles
verify condition of load carrier
fill & drain feedwater reservoir
drain used water reservoir
current guidance documents for sterilisation
SHTM 01
referencing BS EN 285 & BS EN 13060
major factors to consider in decontamination
- time
- temp
- water
- chemicals
- energy
4 elements of sinner circle
energy
chemicals
temperature
time
what detergents can be used (3)
- high & low alkaline detergent for enclosed processes (not designed to be in contact with skin)
- enzymatic detergent breaks protein into smaller particles
- pH neutral detergent is less harmful to operator skin
factors for manual cleaning
water - tap water
temp - <35 degrees
time - dependent on operator
chemicals - pH neutral / enzymatic detergent
energy - scrubbing with brush
factors for ultrasonic
water - tap water
temp - < 35 degrees
time - dependent on validated cycle time
chemicals - pH neutral / enzymatic detergent
energy - ultrasonic sound waves
factors for WD
water - cleaning stages can use tap water
temp - dependent on chemical validated with process <65
time - dependent on validated cycle time
chemicals - low / high alkaline detergent
energy - water jet / spray
factors for thermal disinfection
water - water conductivity lower than <30ms recommended
temp - 90-95 degrees
time - minimum hold time of 1 min
chemicals - must be free from all chemicals
energy - water jet / spray
factors for steam sterilisation
water - pure water
temp - 134-137 degrees
time - minimum hold time of 3 mins
chemicals - free from all chemicals
energy - steam heat energy
current guidance
SHTM 01 part C
SHTM 01 part D
current legislation
health and safety at work act 1974
medical device regulation (MDR 2017/745)
current standards
BS EN 285 & BS EN 13060 - for sterilisers
BS EN 15883 & 12006 - for disinfectors
