Patient Safety Flashcards
What is Spaulding classification?
Classifies instruments as critical (must be sterile), semi-critical (ideally sterile/high level disinfected) or non-critical (disinfect or clean)
Dental mirror Spaulding classifictation
Semi-critical
Dental handpieces challenge of sterilisation
Sterilising inside the instrument, getting steam to penetrate
What type of sterilisers for lumened instruments?
Type B vacuum
Why must instruments be sterilised?
Reduces probability of infection transmission
International standard for surgical instruments
Legislative and professional standards
Maintaining high quality patient care
Do type N sterilisers sterilise dental handpieces?
No, they are non-vacuum
Sterile definition
For a terminally sterilised medical device to be designated STERILE the theoretical probability of there being a viable micro organism present on/in the device should be equal to or less than 1 x 10^-6
Lifecycle of re-usable surgical instrument
(acquisition)- cleaning - disinfection - inspection - (disposal) - packaging - sterilisation - transport - storage - use - transport - cleaning
What is a good tip to keep sterilisation guidelines simple?
Single use devices where possible
What is the next step after disinfection and inspection?
Packaging
What is the next step after packaging of instruments?
Sterilisation
Three main factors in the reduce of spread of hepatitis B in dentistry?
Modern sterilisation requirements
PPE
Vaccination
Reasons to be concerned about CJVD
Prions more difficult to inactivate on surgical devices
Infectivity can survive steam sterilisation at 134C for 18 minutes
Asymptomatic carriage may be relatively high
Possible bacterial cause of post-op infection
Staph aureus
How is the inside of a handpiece sterilised?
Type B vacuum steriliser
What is a critical device by Spaulding classification?
A device that penetrates soft tissues, makes contact with broken skin and enters or contacts the bloodstream or normally sterile tissue
What is a semi-critical device by Spaulding classification?
A device that comes into contact with non-intact skin or mucous membrane, but does not penetrate soft tissue or make contact with the bloodstream, bone, or normally sterile tissue
What is a non-critical device by Spaulding classification?
A device that only comes into contact with the skin and intact mucous membrane
What are the Standards of decontamination that must be achieved?
BS EN
What are the guidance documents used for decontamination standards called?
SHTM
What does the cleaning stage of the decontamination cycle do?
Removes all of the biological matter from the surface of the instruments following use
Reasons instruments must be cleaned (5)
Functionality of instrument
To minimise spread of contamination
To prevents failed procedures such as biopsy
To achieve steam contact - can’t sterilise through bacterial matter
It is a legal requirement
Which machine is recommended for cleaning?
Washer disinfector
What is the second most preferred method of cleaning?
Ultrasonic Bath
When can manual cleaning be carried out?
If it is the only option
It is specifically recommended by the manufacturer’s instructions
Washer disinfector automated process has failed to remove the contamination
What is the difference between Type B/Type N sterilisers?
Vacuum/non vacuum
First 3 things to do upon entering decontamination room?
Set down dirty instruments
Hand hygiene
PPE
What is the next stage after using the washer disinfector?
Inspection
3 methods for cleaning stage, and what this stage is designed to do
Washer disinfector
Ultrasonic bath
Manual
Remove biological matter
What PPE should be worn in the LDU?
Apron
Face shield
Gloves
What PPE is worn for manual cleaning specifically, and why?
Heavy duty rubber gloves
Risk of sharps injury
What does LDU stand for?
Local decontamination unit
Requirements for manual cleaning
There must be a dedicated sink
Another sink is required for rinsing
Standard potable water or tap water can be used
Water must be 30-35C
(Temp in excess of 35 can cause proteins to coagulate)
Chemical detergents must be used in the process
Detergents should be formulated specifically for manual cleaning, generally an enzymatic or pH neutral detergent
Manufacturers instructions always followed for dosing levels of chemicals
Two manual cleaning methods
Immersion
Non-immersion
Why is important to scrub below the surface of the water in manual cleaning?
Can create aerosols and splash environment
Instruments in contact with water and detergent - better cleaning
Two reasons that you must follow the recommended temperature of water for manual cleaning
Temperatures above 35C can cause protein coagulation process to start
Recommended temperature for chemicals must be used as this could damage the efficacy of the chemicals, especially enzymatic
What type of brush should be used for manual cleaning?
Long handled soft bristled, preferably one that can be cleaned through a washer disinfector
NEVER metallic - could scratch passivation layer
What is the passivation layer?
Layer on surface of instruments that prevents corrosion
How does the ultrasonic bath work?
It uses soundwaves at very high frequencies to produce bubbles, then fluctuations in pressure produced by the sound waves cause the bubbles to rapidly expand and collapse, having a scouring effect on instrument surface
(has potential to damage instruments so always check manufacturers instructions)
What is cavitation?
The process in ultrasonic bath where soundwaves are used to produce bubbles, then fluctuations in pressure which cause the bubbles to rapidly expand then collapse
Operating temperature of ultrasonic bath
20-30C
Can tap water be used in the ultrasonic bath?
Yes
Should a chemical be added to the water in the ultrasonic bath?
Yes
What must be done to ultrasonic bath before it can be used to clean instruments?
Degas cycle must be run - If pre existing bubbles, any produced by the cavitation process will collapse into them
How is a degas cycle carried out
Chamber filled with water and detergent
Standard production cycle ran with empty chamber (except for the load carrier)
Information recorded following use of ultrasonic bath
Date
Cycle number
Detergent added
Temperature
Time
Operator name
What must be carried out immediately after use of the ultrasonic bath?
Rinsing - separate sink, below surface of the water
If washer disinfector process fails, so manual and ultrasonic cleaning are used, what must be done next?
Rinsed, then run through washer disinfector again
Advantages of manual and ultrasonic cleaning
Manually scrubbing exerts greater force than WD is capable of
Some pieces of equipment can not be run through the WD in-line with manufacturer’s instructions
Ultrasonic baths are very good at removing contamination
Reasons against manual and ultrasonic cleaning
A member of staff must be present the whole time
Risk of aerosol production
Risk of contaminating surrounding environment
Potential for inconsistency due to human error
High risk of sharps injury
Ultrasonic process is ferocious and could potentially damage equipment
No automated water changes in ultrasonic bath - could recontaminate as removed from chamber
Stages of washer disinfector cycle
Flush/prewash - saturate the contamination and removes gross contamination
Main wash - supplemented by detergent to more effectively remove biological matter
Rinse - removes any remaining biological or chemical residue
Thermal disinfection - actively kills microorganisms with use of heated water
Drying - hot air used to remove any remaining moisture from the surface
What happens between each stage in the washer disinfector cycle?
Water is changed (automatically)
When are proteins/prions removed from instruments?
During the cleaning stage of the decontamination cycle, ideally in washer disinfector, but manual washing and ultrasonic bath can be used if this does not remove all biological matter
Why is important to remove proteins and prions in the washer disinfector?
They can survive high temperatures for long periods of time so will not be removed during sterilisation stage
Temperatures of WD stages
Prewash - <35C
Main wash - dependent on detergent
Rinse - <65C
Thermal disinfection - 90-95C for min 1minute
Drying - not specific but generally 100C
Why is washer disinfector the first step?
Save bother/staff for manual cleaning if WD works well to remove all contamination
There is fresh water for each stage
Thermal disinfection makes instrumentation safe for staff to handle so that inspection can take place before steam sterilisation
Consistency
Traceability
Daily checks for the washer disinfector
Check that spray arms spin freely without obstruction
Check spray jets on arms are not blocked
Make sure there is not debris on the strainer/filter and no parts of instruments or other potential blockages
Check door seal and wipe clean if necessary
Verify there is a suitable amount of chemical in reservoir
Record disinfection temp of the first cycle daily (ACT automatic control test)
Where are the spray arms in a washer disinfector?
One on the bottom of chamber one on the top
Why is loading the washer disinfector correctly important?
For sufficient cleaning the water and detergent must contact every surface of every instrument
Loading of washer disinfector requirements (5)
Load carrier must be used
Clip trays must be used and positioned correctly
No overlapping or shadowing of equipment
Hinged instruments must be open at hinger
All assemblies should be disassembled before hand
What must be carried out after using the washer disinfector and for what 2 reasons?
Inspection under illuminated magnifier - for damage to instruments and to check there is no contamination still present
Why is steam used for sterilisation?
Steam carries a massive amount of energy
Non-toxic component in the sterilisation process
For certain applications it can be recondensed and used again
The main ingredient is water - readily available
There is no waste product except water
What must be used for steam production for sterilisation?
Purified water - had organics, minerals and microorganisms removed from it
Why is it useful that steam, compared with the amount of water used to create it, has a much bigger volume?
Can flood the chamber with small amount of water
High pressure, helps with permeability of steam
Three types of steriliser
Type N
Type B
Type S
What is a type N steriliser?
Most basic
Autoclave
Also called gravity displacement
What is a type B steriliser?
Most robust cycle
Vacuum
What is a type S steriliser?
Specialised piece of equipment for a specific piece of equipment
Process of type N sterilisation
Machine heats water in chamber
Turns to steam and passively forces air out (not entirely efficient and can leave pockets of air in chamber)
Not favourable for high quality sterilisation and wrapped or lumened instruments can’t be processed
Which instruments can not be processed in type N steriliser?
Wrapped or lumened
What are the problems associated with air pockets in sterilisers?
Air pockets are always colder than the steam - not heated or maintained in the same way
If instrument is in air pocket it is not contacting the steam, might not reach sterilisation temperature for the minimum required time
What instruments are recommended to be sterilised in type N?
Only rigid steel/solid instruments with no pockets, channels or lumens, unwrapped
Required temperature and pressure of type N, and how long must this be maintained?
134-137C
2.05-2.45 bar gauge
3 min
Process of type B steriliser
Empty chamber of all air with vacuum pump
Fill chamber with steam
Advantages of type B steriliser
Vacuum so more effective at having steam contact all instrument surfaces at all times
Can penetrate wrapped instruments allowing them to be sterile at the point of use
Required temperature and pressure for type B steriliser, and how long must this be maintained?
134-137C
2.05-2.35 bar gauge
3 min
Extra stage of type B steriliser
Drying stage to remove moisture
Process of type S steriliser
Washes and lubricates hand pieces as well as sterilising them
Has a vacuum process but can not process wrapped instruments
Same temperature, pressure and hold time
Only used for instrument it is designed for
When do instruments get wrapped if they are sterilised in type N?
Immediately after
What stage in the disinfection process should instruments be wrapped?
Before sterilisation (type B)
Immediately after sterilisation (Type N)
Suitable environment for storage of wrapped instruments
Clean and free from aerosol contamination, dry, temperature controlled, away from direct sunlight, first in first out
Daily tests for sterilisers
Check door seals, clean if necessary
Verify chamber is free from damage, debris, contamination, instruments
Verify condition of load carrier
Fill and drain the feedwater reservoir
Drain the used water reservoir
(steam penetration test for type B)
What daily test must be carried out on specifically type B sterilisers?
Steam penetration test using Bowie Dick test pack or Helix
Weekly tests for type B sterilisers
An air leakage test
Air detector function test
Both cycles on the machine
Guidance for sterilisation documents
SHTM 01 - 01 part c
referencing BS EN 285 and BS EN 13060
Why is sterilisation carried out?
Destroy all viable microorganisms
Requirements for instrument transport container
Rigid sided
Tight fitting lid
Leak proof
Colour coded or clearly marked
Requirements for washer disinfector
Validated to establish cycle parameters
Loading patterns followed
Daily and weekly testing carried out
Requirements of the inspection stage
A lit magnifier used to identify any damage and identify any spots or residual contamination
What is ultrasonic bath used for?
Remove hard to reach contamination
As a secondary or back-up method
Requirements for ultrasonic bath
Must be degassed and tested before use
Requirements for sterilisers
Must be tested on daily and weekly basis
Use purified water only
Have an annual insurance test performed
Where in the disinfection process must purified water be used?
Steriliser
Why is time between use and decontamination processing significant?
Blood or biological matter dry and adhere to the instruments
Elements of Sinner circle
Energy
Temperature
Chemicals
Time
What does the Sinner circle show?
4 key elements that are required for a successful cleaning process
If any component is increased or decreased the efficacy of the cleaning process is changed
(developed by Herbert Sinner in the 1950s)
Where can potable/tap water be used?
Manual
WD
Ultrasonic
What may be present in tap water?
Minerals
Silicates
Organics
Metals
What is conductivity of water?
Total dissolved solids, such as minerals, silicates, organics, metals
Measure in micro-siemens
Soft water has lower conductivity
56.8 micro-siemens in Scotland
How is water purified?
Distilled
De-ionised
Reverse osmosis
Sterile
How is distilled water produced?
Boiling and recondensing tap water
How is de-ionised water produced?
Passing water through an ion exchange that picks up things like sodium, calcium and potassium
How is pure water produced by reverse osmosis?
A semi permeable membrane filter is used to remove particulate and bacteria from the water
How is sterile water produced?
Filtered by distillation/deionisiation/reverse osmosis them sterilised
Why is it important to only use pure water in the sterilisation stage?
Any particulates from water left on instruments when they are dried can leave a residue giving bacteria a place to breed
Where are enzymatic detergents used and why?
In ultrasonic and for manual washing in order to break proteins down into smaller particles
Benefit to pH neutral detergent for the operator?
Less harmful for skin
Where are high and low alkaline detergents used and why?
Enclosed processes - harsh on skin
Where is pH neutral detergent used?
Manual washing or WD for handpieces
How to detergents work?
The chemical molecule is designed to have a hydrophilic and a hydrophobic end. The hydrophobic end never contacts water, because of the repulsion
This is where the contamination is drawn to and then flushed away as the hydrophilic end attaches to water molecules
What are the important manufacturer’s instructions for detergents?
Dosing
Operating temperature
What is the energy element in manual/ultrasonic/WD cleaning?
Manually - force of scrubbing brush
Ultrasonic - high frequency waves
WD - high pressure (1-1.5 bar)
Why does the WD use stronger chemicals that ultrasonic or manual washing?
Lower energy process
How are times of WD cycles established?
At validation by engineer - instruments must be free from biological matter/proteins within the cycle parameters
During which stages of the WD must the temperature be below 35C?
Flush/prewash (avoid protein coagulation)
What temperature is the water for manual or ultrasonic cleaning?
<35C
Thermal disinfection temperature
90-95C
1 minute minimum
Steam sterilisation temperature
134-137C
3 minutes minimum
What temperature is used in the WD for the main wash process?
Manufacturer’s instructions
What are Scottish Health Technical Memorandum?
A series of documents providing information and guidance on testing requirements for decontamination equipment etc.
Legislation for decontamination
Outlined in government publications such as Acts and Directives, legal obligation to operate any form of decontamination facility in line with the official guidance provided. Also governs production and manufacture of equipment
Standards for decontamination
A series of highly technical documents (BS EN, BSI, ISO) which govern the way in which facilities and equipment should be operated and amongst other things, the standard to which equipment is produced and processes are tested and verified.
Current guidance for sterilisation
SHTM 01-01 Part C
Current guidance for automated cleaning and disinfection
SHTM 01- 01Part D
Standards for sterilisers
BS EN 285 Sterilisation - Steam sterilisers - Large Sterilisers
BS EN 13060:2014 Small Steam Sterilisers
Standards for washer disinfectors
BS EN 15883
