Sterilisation, Preparation of the Patient and Preparation of the Surgeon Flashcards
Define sterilisation
destruction of all microorganisms on or in an object.
Define disinfection
anything less than sterilisation and may be high-, intermediate- or low-level depending on the range of microorganisms killed.
What pH detergent provides the best material compatibility profile and soil removal?
What is often added to assist in removing organic material?
Neutral
Enzymes (proteases)
What process do ultrasonic cleaning devices use?
Cavitation
(creates minute gas bubbles that implode on contact with surgical instruments, creating a vacuum that removes partical and debris)
What properties should the ideal packaging be? (5)
Permeable to steam
Resistant to heat/physical
Long lasting
Durable
Effective barrier to microorganisms
Can you think of some events that might result in contamination of stored surgical instruments? (8)
Damage to the packaging, such as tears
Packaging becoming wet
Type of packaging material
Storage conditions, i.e. open or closed shelves
Temperature
Humidity
Air movement and traffic
Level of contamination in the environment.
What are the autoclave time and temp for a gravity displacement autoclave?
30 minutes at 121°C
What are the autoclave time and temp for vacuum autoclave?
4 minutes at 132°C
How do Gravity-displacement autoclaves work?
Gravity-displacement autoclaves introduce steam under pressure. Being lighter than air, steam rises and forces air out of a valve at the bottom of the unit. The coldest air is therefore always being forced out of the bottom of the unit and is used to measure the temperature of the autoclave, confirming that sterilisation conditions are being met. The efficacy of sterilisation depends on steam coming into contact with all the items in the autoclave.
What does the efficacy of gravity displacement autoclaves rely on?
steam coming into contact with all the items in the autoclave.
How do pre vacuum autocalves work?
Pre-vacuum autoclaves use a pump to remove air from the chamber prior to the introduction of steam, leading to a rapid and uniform distribution of steam
What detects leaks and inadequate air removal in pre vacuum autoclaves?
A Bowie-Dick test is used to detect air leaks and inadequate air removal. This consists of testing the efficacy of sterilisation of folded cotton towels.
What is ethylene oxide?
colourless and odourless gas,
What is the boiling point of ethylene oxide?
10.5C
How does ethylene oxide sterilise?
It causes alkylation of proteins and nucleic acid, obstructing cell division and reproduction, and is used to sterilise medical equipment that is heat or moisture sensitive
What concentration should ethylene oxide be?
450-1200 mg/l
What temperature should ethylene oxide be?
37-63C
What humidity should ethylene oxide be?
40-80%
What is the exposure time of ethylene oxide?
1-6 hours
What reduces ethylene oxide flammability? (2)
mixed with carbon dioxide or hydrofluorocarbon
What is the aeration period of ethylene oxide
This is 8-12 hours at 50-60 °C and modern ethylene oxide sterilisers incorporate this into the sterilisation cycle; this results in lengthy sterilisation times.
What is a major human disadvantage of ethylene oxide?
carcinogenic
What phyiscal indicators are recorded for:
Steam sterilisation (3)
Eythylene oxide (2)
For steam sterilisation this includes cycle time, temperature and pressure.
For ethylene oxide, time and temperature are recorded.
How do chemical indicators of sterilisation work?
Chemical indicators react to specific parameters that are critical to the sterilisation process, typically by a colour change. They confirm that one or more of the conditions of sterilisation have been met but not that the contents have been sterilised.
Which biological indicator is used for steam sterilisation?
Geobacillus stearothermophilus spores
Which biological indicator is used for ethylene oxide sterilisation?
Bacillus atropheus spores
What are bioloigcal indicators?
Negatives (2)
Biological indicators consist of a culture of microorganisms that is evaluated after processing to determine its viability.
These tests are more expensive and time-consuming than chemical indicators, so are not suitable for day to day use, instead being used every 1-2 weeks as a failsafe to confirm the efficacy of chemical indicators.
What does The immediate action of an antiseptic refer to?
the number of microorganisms killed or mechanically removed within the first 3 minutes of applications. This is important as it equates to the time spent preparing the patient or, in the case of the surgeon, scrubbing up;
What does The persistent action of an antiseptic refer to?
to prevent re-colonisation of the skin within 6 hours of its application. This is also important as it corresponds to the time that the patient and surgeon are in theatre and the immediate post-surgical period when the surgical wound is most vulnerable. This property is now often referred to as the sustained action;
What does The residual action of an antiseptic refer to?
to a cumulative anti-microbial efficacy after repeated application of an antiseptic over at least 5 days. The importance of this is unknown.
What concentration of ethanol have been shown to have greater efficacy against a wide range of fungi, viruses and spores, and are now commonly used as an alternative to traditional surgical hand scrubbing preparations?
80%+
How do alcohols’ sterilise?
denature proteins, interfere with metabolism and cause lysis of cells.
What is the efficacy of alcohol reduced by?
Their efficacy is reduced by the presence of organic debris, so this should be removed by washing prior to their application.
80% ethanol has an action of how long?
up to 6 hours
Why should alcohol not be applied to open wound?
Cell necrosis
Iodophors:
Action time?
Reduced by?
Rapid immediate
Organic debirs
What is the sustained action of iodophors?
4-6 hour
What is the problem in 50% of the time using iodophors?
Contact dermatitis
Chlorhexidine class?
cationic bisbiguanide,
Chlorhexidine:
Action time?
Rapid immediate
Chlorhexidine is ototoxic and neurotoxic when applied to the middle ear, what concentration can cause occular damage?
> 0.05%
What is the benefit of chlorhex over iodine?
Not effected to the same degree by organic debris
Chlorhexidine effect time?
6 hours
Chlorhexidine effect time?
6 hours
What is the benefit of chlorhex over iodine?
Not effected to the same degree by organic debris
Benefits of re-usable drapes?(2)
Environment
Cheaper
Negatives of reusable drapes? (3)
Barrier properties reduced with laundry Tears in material
Linting of material into surgical site
Benefits of disposable drapes? (4)
Always new
Sterile
No laundry/sterilisation cost
Better barrier
Negatives of disposable drapes (1)
Increased cost
Are you aware of the factors that increase the risk of perforation to surgical gloves? (6)
Surgery >1 hour
Ortho Sx
Powered instruments
Ortho wire
Gloves with polyisoprene
Being primary surgeon
