WDs Flashcards
housekeeping duties
check spray arm for rotation/free movement and blockages
remove and clean strainers and filters etc
ensure sufficient additives available and that dosing system is fct
door seals for any wear/tears, wipe
check load carrier
daily tests
housekeeping duties
check spray nozzles for blockage - paying particular attention to those fitted to carriages for cannulated instruments
note disinfection temp of 1st cycle
check grommets/seals holding control probes etc for deterioration due to chemicals used
PCD (optional)
check enough paper in printer (unless has SD card)
check no instruments/parts from prev cycles
who carries out the daily tests?
user
what document gives guidance?
SHTM30
who carries out weekly tests?
user or CP(D)
weekly tests
weekly safety checks daily tests water hardness (all process stages) water conductivity (final rinse stage - thermal disinfect) cleaning efficacy test (by residual soil detection) - test soil, PCD protein detection full ACT
weekly test sheet
water conductivity (thermal disinfect)
cleaning efficacy
- test soil, PCD
protein detection
= batch number, expiry date, cycle number, result. Date of test, name, signature
why is it preferred to manual cleaning?
automated cleaning more control and reproducibility
more readily validated
involves thermal disinfection
stages of WD
prewash/flush wash rinse thermal disinfection drying
temps of stages
prewash/flush 30-35
wash 60-65
rinse 40-45
thermal disinfection 90-95
prewash/flush
remove largest part of any biological matter
low temp stage to hydrate and loosen any contamination
why is prewash/flush at temp 30-35?
don’t want to coagulate proteins
wash stage
heated with chemical
circulated for longer time to remove as much organic matter from the instruments as possible
rinse stage
final stage of ‘cleaning’
98% of contamination should have been removed
thermal disinfection - why is it important all proteins have been removed before?
because high temp can bake proteins onto the surface
of instruments
which stage has water conductivity checked and what is measured?
thermal disinfection
TDS and identify if still high levels of particulate
values of thermal disinfection
90-95 degrees for min 1min
essential contact time 12s
aim of thermal disinfection
actively kill and remove bacteria
drying
remove any excess moisture which may still be present after the prev stages
water has the potential to inhibit the sterilisation process as well as damage any wrappings
function
wash load and inside of machine
disinfect load and inside of machine
dry load
perform the above without damaging the device
perform the above without contaminating the env
perform the above and fully drain the machine prior to the next load
what is the ACT?
test automatic control of machine using a stopwatch
can verify that each stage achieves the temp set for that stage, as well as lasting for the required amount of time. Can also verify that this info is displayed properly
how often should an ACT be carried out?
daily, do manual on a weekly basis
advantage of ACT in terms of problems
can use diagnostically to identify potential problems/issues
if have record of data - can give it to service engineer who will be able to diagnose what is happening more accurately
- less time as is easier to diagnose an issue by analysing the recorded data
- less money and less downtime for repair
ACT - when should test be considered as passed?
any visual display indicates ‘cycle complete’
during the whole of the operational cycle the values of the cycle variables, as recorded by the WD systems and any independent monitor are within the limits established by the manufacturer during the performance qualification testing
during the disinfection stage the WD record and any independent monitoring system are within the disinfection temp and hold period requirement defined in EN ISO 15883 and the performance qualification tests
the door cannot be opened until the cycle is complete
person conducting test does not observe any mechanical or other anomaly
ACT info to record
for each stage:
- temp - midpoint
- time each stage is active for
- disinfection start and end with stage duration
- vol of chemical dosed
- cycle time overall
date and time cycle no operator machine indicated cycle complete daily checks carried out
manually written record and machine print out/document
which cycle should an ACT be done on?
short standard
Ao value
in reference to the expended energy within the cycle and establishes a value that informs us of the kill rate of the disinfection within a WD
time required to achieve a specified log reduction of MOs based on the temp of the thermal disinfection cycle
described by ENISO 15883
number following the Ao symbol represents the number of seconds needed at 80 degrees to achieve the level of disinfection specified by the particular Ao designation
combination of time and temp
Ao required values
surgical instruments Ao 600
EN ISO 15883 specifies WD must be capable of achieving Ao 3000
ACT sheet and machine print out
sheet manually filled in
machine print out produced by the data logger fitted to the machine
certain info can only be obtained from the print out e.g. the cycle number or the volume of chemicals dosed
check the record we created against this one for accuracy
small deviations in the info are accepted as you can only look at one thing at a time
- being a couple of seconds off or half a degree out are accepted, unless it goes outwith the temp or time bandings
prewash time on machine longer - water needs to enter chamber and machine reach required temp
what does the cleaning efficacy (soil) test verify?
it verifies soil removal - verifies all 4 elements of the Sinner circle set correctly
cleaning efficacy (soil) test - when should you abort the cycle?
after wash
at end of rinse - as soon as screen says disinfect press stop
some equipment might have an access hatch that the instruments used, or the PCD, can be removed from
PCDs
e.g. soil strip
serious loading concerns
FMIs and verified to suitable efficacy before production testing - otherwise false positives
generally longer shelf lives
can sometimes be temperamental during washing and produce false positives if not processed exactly to requirements
test soil storage
generally needs to be stored in fridge and has short shelf life
test soil - specific mixture
use Edinburgh test soil or Browne’s dehydrated test soil
purpose of test soil
coat and dry onto the surface of the instruments in the same way that biological matter would
can then process this instrumentation and simulate the soil removal process that we subject our instruments to, and verify that it is being carried out properly
coating instrument with test soil
put thin layer on surface - esp on hard to remove parts e.g. hinges
dry 30mins-2hrs
- ensure spread even and thin, no lumps
parts of cycle for cleaning efficacy test and what to do after
pre-wash, wash, rinse
unload, inspect under illuminated magnifier
when does the protein detection test take place?
once retrieved instruments/PCD
function of protein detection test
to verify that all viable proteins have been removed from the surface of the instruments, and the wash process continues to be sufficient and effective
how is the protein detection test carried out?
swab surface - jaws, hinges, textured part
- can do on diff instruments than cleaning efficacy
don’t contaminate swab with any other proteins in env - own skin, hands, hair particles
place swab in solution and break off stalk. Cap on top, set aside
components of protein detection test
sterile swab and protein detection solution
- kits in batches - solution within each test kit will only ever be from a single batch - so controls verify it
protein detection tests controls
swab instruments
negative control - sterile swab, no colour change
positive control - swab with protein source - often with kit solution, colour change
after protein detection test
don’t discard tests immediately
they are identifying particles of protein so may take a while for colour change depending on ppm
FMIs
which stages is tap water usually fine?
cleaning - flush, wash, rinse
unless in high limescale areas conductivity should be verified to be <300uS
what water should be used for thermal disinfection?
purified water or water of a sufficiently low conductivity and hardness
limit <30uS for conductivity, <125mg/L CaCO3
what does conductivity measure and what is the consequence?
identifies if there is particulate present within the water
if used during the thermal disinfection stage may lead to mineral deposits and scaling on instrument surface
this particulate (salts, Ca, Mg, strontium) can interfere with the efficacy of the chemical, potentially, and cause operational problems for WDs such as blocking spray jets or coating heating elements
conductivity meter
placed within a sample of water and the conductivity reading will be displayed on the screen on the device
what may need to be done to achieve the required low conductivity?
filter/install pure water supply
who carries out quarterly checks?
CP(D)
quarterly checks
weekly safety checks and functional check of engineering services
carry out daily and weekly tests
verification of calibration
thermometric tests for disinfection
cleaning efficacy test: using test soil
- reference load
- general instruments endoscope/ UIS instruments
doors and door interlocks - cycle start, in-cycle interlock, double door WDs, fault indication on sensor failure
chemical dosage check - ensure parameter remains within tolerance, calibration, limits and fct, inc fault/alarm, of the independent monitoring system
WD key info
general - date - operator - cycle start time cycle data - cycle no - wash temp - disinfection temp - cycle duration was detergent added did cycle complete successfully
info from first cycle of day
date time started operator cycle number disinfection temp daily tests performed detergent added disinfection successful machine identified cycle completed successfully
fault register
not mandatory but should try to maintain one did any faults occur during processing? if yes describe corrective action did cycle complete successfully?
= this type of record keeping should take place for each individual piece of equipment in operation within the decon env
designated person for weekly and daily tests
the person the user (or potentially the user themselves) has appointed to carry these tests out
training and records kept
quarterly cleaning efficacy test
carried out by CP(D)
different
uses a full standard load of instruments and is carried out several times for repeatability
guidance for WDs
SHTM 2030
