Aseptic Technique and Sterilisation Flashcards
What is sterility?
Aseptic is not the same as sterile – sterile is a complete removal of all living cells and only applies to inanimate objects.
What are surgical site infections?
Infection occurring at the surgical site within 30 days/1year if implants remain in situ. Need culture and sensitivity test to prove that SSI present.
What are the 3 categories of SSIs?
Superficial incisional
Deep incisional
Organ/space
What are the consequences of SSIs?
- Patient morbidity and mortality
- Revision surgery/prolonged hospitalisation/prolonged wound management
- Increased costs
- Negative client impression
What are the pathogen related factors of SSIs?
Concentration and virulence
What are the patient factors of SSIs?
Systemic disease - diabetes, neoplasia)
Infection
Malnutrition
Geriatric
ASA status
Infection elsewhere
What are the surgery factors of SSIs?
- Classification of surgical wound
- Duration of surgery and GA
- Aseptic technique
- Surgical experience and technique
- Foreign material
What are Halstead’s Principles?
- Change gloves that are punctured or torn
- Minimise tissue trauma
- Maintain good haemostasis
- Irrigate wounds during surgery
- Debride traumatic wounds thoroughly, do not leave necrotic tissue in situ
- Minimise foreign material – sutures and drains
- Avoid dead space
- Close in layers without tension
- Keep surgery time to a minimum
How should the patient be presented for surgery?
Patient should be presented clean, dry, no skin infection at incision site, recently toileted, with patient related SSI risk factors mitigated.
How should a patient be prepped before surgery after anaesthesia?
- Bladder emptied if full
- Manual faecal evacuation/purse string suture if necessary
- Remove hair
- Initial antiseptic skin preparation
What should you use for initial antiseptic skin preparation?
Chlorhexidine, iodine compounds and alcohol - all can be irritating if concentration is wrong. Don’t use these compounds on open wound. Flush this with sterile saline, iodine or water instead.
What is done in theatre?
Final sterile skin prep
Draping
Clothing
Hand disinfection
Gowning and gloving
What is the best method of gloving – open or closed gloving?
Closed
Why is having sterile hands below your gloves so important?
The accepted standard for gloves is that 1.5% of gloves are punctured before use and by the end of surgery 30% are punctured.
What are the steps in order to clean surgical instruments and equipment?
- Immediate rinse/soak after use
- Clean – ultrasonic cleaner or manually scrub with enzymatic detergent
- Rinse thoroughly
- Dry
- Spray with lubricant
- Pack
- Sterilise
For a given method of sterilisation, what are the 2 indicator types that can be used?
Chemical indicators: colour change on exposure to sterilising temperature
Biologic indicators: heat resistant bacterial spores
What is therapeutic antimicrobial use?
Using antimicrobials to treat an established infection. Use beyond the length of the surgery until the infection is cured.
What is prophylactic antimicrobial use?
Using antimicrobials when there is no infection present with the aim of preventing one. Use immediately before the surgery, during and up to 48 hours post-surgery.
What is an example of when prophylactic antimicrobials would be used?
If the consequences of infection would be catastrophic, such as in orthopaedic surgery.
Which prophylactic antimicrobial should be used?
- Bactericidal
- Spectrum of activity against the organisms likely to cause SSIs in that population
- Should remain at effective levels for 4-6 hours post-op
- Available in IV formulation in your practice
How are surgeries classified?
Clean
Clean-contaminated
Contaminated
Dirty
What is a clean surgery?
Elective, non-traumatic procedure with aseptic technique and primary closure.
Are prophylactic antimicrobials used for clean surgeries?
Not routinely warranted
What are clean-contaminated surgeries?
As for a clean but when you enter GI, respiratory or urogenital tract. There is a minor break in aseptic technique.
Are prophylactic antimicrobials used in clean-contaminated surgeries?
Depends on circumstances
What are contaminated surgeries?
Fresh traumatic wounds, acute non purulent inflammation, gross spillage from contaminated viscous, or major break in aseptic technique.
Are prophylactic antimicrobials used in dirty surgeries?
Antimicrobial use classed as therapeutic, should be based on culture and sensitivity testing.
What is the best way for a surgeon to prepare their hands for surgery?
90 second alcohol hand rub
When preparing a patient for surgery to debride and close a fresh traumatic wound, what should be used to clean the wound itself?
Sterile saline
Define sterilisation.
The destruction/removal of all living cells, viable spores, viruses, viroids and prions from an inanimate object or habitat. Chemicals (sterilants) and physical means are available.
Define disinfection.
The destruction/removal or inhibition of microorganisms capable of causing disease from an inanimate object. Some vegetative cells and bacterial spores will remain following disinfection. Chemicals (disinfectants) and physical means are available.
Define sanitation.
The reduction of a microbial population on an inanimate object to levels considered safe by public health standards.
Define pasteurisation.
The inactivation of human pathogens and non-pathogenic spoilage organisms from milk, beer, wine and other beverages. Most other vegetative cells will also be inactivated but spores will remain.
Define antisepsis.
The destruction/removal or inhibition of micro-organisms from living tissue to prevent infection and disease. The chemicals used are less toxic to tissue than disinfectants would be.
Define germicide.
A chemical able to kill microorganisms (bactericides, fungicides, viricides)
What are the 4 categories of physical antimicrobial agents?
Moist heat
Dry heat
Radiation
Filtration
What is moist heat sterilisation?
Degrades nucleic acids, denatures enzymes and other essential proteins, and possibly denatures cell membranes.
Name the methods of moist heat sterilisation.
Boiling/steaming
Autoclaving
Tyndallisatoin
Pasteurisation
How does boiling/steaming sterilise?
To ensure all death, 10 mins at 100˚C. prions can survive this, even if extended for several hours. So this is useful to disinfect objects not harmed by water but it does not sterilise.
How does autoclaving sterilise?
15psi, 121˚C, 15-20 mins. Destroys all microorganism and spores. Materials suspected of prion contamination should be soaked in 1N NaOH for 1-2 hours/overnight prior to autoclaving.
What must be used with each autoclave run?
Indicators - to ensure that the necessary conditions have been reached.
How does tyndallisation sterilise?
90-100˚C, 30-60 mins, incubated overnight at 37˚C to enable any spores to germinate. Then repeated once a day for 2 days. Only method for killing spores but is time sensitive and not widely used.
How does pasteurisation sterilise?
72˚C, 15 seconds, then rapid cooling, which discourages growth of thermophiles and spores. This is not sterilisation procedure – spores will survive.
Name the 2 methods of dry heat sterilisation.
Hot air oven
Incineration
How does hot air oven sterilise?
160-170˚C, 2-3 hours. Glassware, metal and products ruined by water. Suspected prion contamination should be soaked in 1N NaOH for 1-2 hours prior and dry for an added 4 hours.
What can incineration sterilisation be used for?
If material/object is disposable
Name the 2 methods of irradiation.
UV radiation
Ionising gamma radiation
How does UV sterilise?
260nm absorbed by DNA causing thymidine dimers, which inhibit replication and function. Sterilisation of air and exposed surfaces.
How does ionising radiation sterilise?
Can sterilise equipment unlike UV. Heat labile solutions of drugs, hormones and enzymes can be sterilised. Not suitable for routine veterinary hospitals.
How does filtration sterilise?
Material is forced through the filter under pressure or drawn through it by vacuum. Sterilisation of heat or radiation sensitive material
What are the 7 categories of chemical antimicrobial agents?
Phenolics
Alcohols
Halogens
Quaternary ammonium compounds
Aldehydes
Sterilising gases
Miscellaneous
What is a potential problem with chemical antimicrobial agents?
Many of these chemicals are inactivated to some degree in the presence of excess organic matter. It is therefore advisable to clean the object/site prior to treatment.
How do phenolics sterilise?
Disinfectants – protein coagulation and cell membrane disruption
What are the advantages of using phenolics?
- Not inactivated by organic material
- Residual effect on surfaces
- Kill mycobacterium tuberculosis
What are the disadvantages of phenolics?
- Skin irritants
- Objectionable odours in some
- Creosol inactive in hard H2O
How do alcohols sterilise?
Disinfectants/antiseptics – protein coagulation and cell membrane disruption
What are the advantages of alcohol sterilisation?
- Kill mycobacterium tuberculosis
- Flammable for flaming instruments
What are the disadvantages of alcohol sterilisation?
- Skin drying
- Inactivated by organic matter
- Flammable (dangerous)
Name the 2 halogen sterilisations.
Chlorines
Iodophors
What are the advantages of using chlorine sterilisation?
- Kill mycobacterium tuberculosis
- Corrosive
- Inactivated by organic matter
What are the disadvanatges of chlorine disinfection?
Bleaching
What are the advantages of iodophor sterilisation?
- Cleaning
- Residual effect on surfaces
- Fading colour indicates loss of activity
What are the disadvantages of iodophor sterilisation?
Only kills mycobacterium tuberculosis only as tinctures
What is the advantage of quaternary ammonium compounds?
Cleansing
What is the disadvantages of quaternary ammonium compounds?
- Does not kill mycobacterium TB
- Does not kill pseudomonas aeruginosa
- Inactivated by hard H2O
- Inactivated by soap
What is the advantage of aldehyde sterilisation?
Broad spectrum
What are the disadvantages of aldehyde sterilisation?
- Inactivated by organic matter
- Causes contact dermatitis
What is the advantage of ethylene oxide gas sterilisation?
Rapid penetration of packing material, including plastic wraps
What are the disadvantages of ethylene oxide gas sterilisation?
- Special equipment needed
- Residual EO must be removed by aeration due to high toxicity
What are 5 miscellaneous methods of sterilisation?
Chlorhexidine (Hibitane)
Anionic detergents
NaOH
3% hydrogen peroxide
Heavy metals
