Aseptic Technique

Question 1

What is asepsis?
What is sterile?

Answer 1

Process of removing pathogenic microorganisms or protecting against infection by these organisms.
Carried out on living tissue.
Normally used in context of surgery or invasive procedures.
Not a complete absence of pathogens – minimise level of contamination.
Not the same as sterile!

Compete removal of all living cells, only applies to inanimate objects.

Question 2

Why is asepsis important?

Answer 2

To minimise surgical site infections (SSI).

Question 3

What are surgical site infections?
Percentage occurrence in SA surgery?
Consequences of SSI?

Answer 3

Infection occurring at the surgical site within 30 days (or within 1 year if implants remain in situ).
2-18.1%.

Patient morbidity and mortality.
Revision surgery/prolonged hosp. / prolonged wound management.

Question 4

What is the risk of SSI determined by?

Answer 4

Pathogen related factors: conc. and virulence.
Patient factors: systemic disease, infection, malnutrition, ASA (American Society of Anaesthesiologists) status.
Surgery factors: Surgical wound classification, surgery duration, aseptic technique (inadequate skin prep, skin damage during clipping), surgical experience and technique, foreign material (implants, suture material, drains etc).

Question 5

SSI prevention.

Answer 5

1. ASEPTIC TECHNIQUE!
2. Pre-op assessment and prep – identify and mitigate patient risk factors.
3. Effective analgesia.
4. Surgical technique – Halstead’s principles.
   – Gentle tissue handling
   – Avoid dead space
   – Close tissues in layer with careful approximation and no tension.
5. Leave as little foreign material in wounds as possible – sutures (esp catgut and non-absorbable), implants, drains.
6. Prophylactic antimicrobials – only where appropriate.
7. Surveillance/clinical audits.

Question 6

Sources of contamination to eliminate?

Answer 6

Patient/surgical site.
Surgeon.
Surgical equipment.
Operating theatre.
Prophylactic use of antimicrobials – inly where appropriate.

Question 7

Equipment that may be needed for patient prep for a surgery e.g. cat spay.

Answer 7

Clippers
swabs
Hibiscrub (Chlorhexidine).

Question 8

Main steps in patient preparation.

What other considerations may be made when it come to larger animals.

Answer 8

1. Remove hair.
2. Clean skin to remove surface oils, dirt, transient pathogens.
3. Antiseptically prep skin to remove pathogens.
4. Drape.

Other considerations:
- Cover feet and tail.
- Ensure no contamination from urine and faeces.

Question 9

How should a patient present for admit before surgery?

Answer 9

• Clean and dry.
• No skin infection at incision site.
• Patient-related factors that increase risk of SSI identified and mitigated where possible.
• Recently toileted.

Question 10

Preparation of the patient in the prep-room.

Answer 10

• Induction of anaesthesia.
• Bladder emptied (if full).
• Manual faecal evacuation/purse-string suture placed (if necessary).

Question 11

Hair removal.

Answer 11

Avoid skin damage, careful, good maintenance of clipper blades.
Use hand to stretch skin taut.
First remove bulk of hair by clipping in the same direction as hair lies.
Then clip against direction of hair to achieve a close clip.
If clipping a large area, there is a risk of blades over-heating/becoming clogged – will need to clean, cool or replace blade during.
Recommended 10-15cm border from incision site.

Question 12

1. Aim of initial antiseptic skin prep.
2. Properties best in the antiseptic?
3. What should be worn by the person carrying out the skin prep?
4. Technique?
5. Difficult areas of the patient to prepare for surgery?

Answer 12

1. Remove gross dirt and oils, eliminate transient microorganisms, begin reduction of resident bacterial flora.
2. Lathering, broad-spectrum, non-irritant.
3. Gloves.
4. Be gentle – Don’t scrub! Gauze swabs are abrasive if used roughly > will result in increased bacteria colonisation post-operatively.
   Work from incision site outwards.
   Once skin is clean, continue antiseptic prep for 5 minutes.
5. Paws, eyes, prepuce.

Question 13

1. Common use of chlorhexidine?
2. Advantages of chlorhexidine.
3. Disadvantages of chlorhexidine.

Answer 13

1. Scrub (2-4%) or disinfectant (0.5-2%)
2. Effective vs bacteria. incl. multiple drug resistant bacteria.
   Active in presence of blood and organic debris.
   Residual activity (binds to proteins in skin).
   Synergistic effect with alcohol.
   Low toxicity.
3. Poor virucide and sporicide.
   May irritate skin.
   Can damage fibroblasts if >0.05% so cannot be used on open wounds.

Question 14

1. Advantages of iodine compounds for patient prep?
2. Disadvantages of iodine compounds for patient prep?

Answer 14

1. Broad spectrum.
   Synergistic effect with alcohol.
2. Inactivated by blood/organic debris.
   No residual activity.
   Stains skin.
   Radiopaque.
   Smells.
   May cause skin reactions.
   Inactivates fibroblasts at >0.05% so don’t use on open wounds.

Question 15

1. Use of alcohol in patient prep?
2. Advantages of alcohol?
3. Disadvantages of alcohol?

Answer 15

1. Commonly used as rinse after surgical scrub or gel-based hand rub.
2. Very effective bactericide.
3. Unsure whether effective against viruses.
   No effect against spores.
   Poor activity if organic debris.
   No residual activity.

Question 16

Patient preparation once in theatre?

Answer 16

Final sterile skin prep is applied in a sterile manner.
Surgeon applies drapes to patient.

Question 17

1. Draping aim?
2. Best drape type?
3. Draping technique?
4. Limb draping?

Answer 17

1. Physical barrier to prevent movement of debris and bacteria from non-sterile area of surgical site.
2. Impermeable, single use disposable drapes best.
3. Can use single fenestrated drape or 4 quadrant technique (place drape closest to you first).
   Drape from ‘clean to dirty’ – don’t move the drape too much once placed.
   Use towel clamps to keep it still.
4. Waterproof layer (e.g. glove) covered by sterile cohesive wrap.

Question 18

What clothing should be worn by everyone in theatre?

Answer 18

Theatre scrubs that are different to consult scrubs and worn only in prep and theatre.
Cap/hood/beard cover – hood is more effective than a hat.
Face mask – Limited efficiency, more important to limit talking whilst in theatre.
Theatre clogs – avoid overshoes – wasteful and increases contamination.

Question 19

What additional wear is needed for the surgeon(s) performing the surgery?

Answer 19

Gown and gloves.

Question 20

1. Goal of hand disinfection by the surgeon.
2. Technique?
3. Which technique is recommended over the other?

Answer 20

1. Remove dirt and decrease bacterial count.
2. Must be bare to the elbow, nails short and rings removed.
   Can use alcohol based hand solution (e.g. Sterilium).
   A rub rather than a scrub so less irritant to the skin.
   Shorter contact time needed (90 seconds).
   Wash hands to remove gross contamination at start of operating day.
   Recommended as better than scrubbing.
   Disinfectant/antiseptic soap used with a scrubbing brush.
   Contact time 5 mins.
   Dry with sterile towel before gloving.
3. Alcohol based recommended over scrubbing as does not cause micro-abrasions to skin, which increases bacterial contamination.

Question 21

1. Ideal qualities of a surgical gown?
2. ‘closed’ gloving.
3. When is ‘open gloving’ used?
4. Why is having sterile hands underneath the gloves so important?

Answer 21

1. Disposable, water resistant, comfortable, breathable.
2. Preferable as hands stay within gown until in the gloves.
3. When a gown is not worn or a short sleeve gown is worn.
4. The accepted standard is that 1.5% of gloves are punctured before use and 30% of gloves are punctured by the end of surgery.

Question 22

Best practice to achieve asepsis in surgical instruments.

Answer 22

Immediate soak/rinse after use to remove blood and debris. Open hinged instruments.
Clean with ultrasonic cleaner or manually scrub with enzymatic detergent and rinse thoroughly.
Dry thoroughly.
Spray instruments with lubricant.
Pack.
Sterilise e.g. autoclaving.

Question 23

1. What are surgical instruments and kits packed in?
2. What type of wrap is preferred and why?
3. Aluminium composite container that is unwrapped.
4. Pack labelling.
5. What must be checked regularly?

Answer 23

1. Sleeves that are paper one side and cellophane the other with the ends having been heat-sealed.
   Advised to double wrap.
2. Crepe papers preferred over cotton wraps. – Crepe papers are durable, with good handling qualities and longer storage times.
3. Only short-term – taken straight from autoclave to theatre.
4. Contents, date and operative.
5. Expiry dates on packs to re-pack and re-sterilise when needed.

Question 24

Types of instrument sterilisation?

Answer 24

Heat sterilisation and chemical sterilisation.

Question 25

1. Types of heat sterilisation.
2. Actions, advantages and disadvantages of these.

Answer 25

1. Moist and dry.
2. Moist – kills by coagulation of critical proteins.
   + Quicker.
   – Very delicate items may be damaged.
   Dry – kills by oxidation and removal of water.
   Rarely used.
   – Time consuming.

Question 26

1. Why would chemical sterilisation be used?
2. 2 types of chemical sterilisation?
3. Disadvantages of these?

Answer 26

1. For items unsuitable for steam sterilisation e.g. endoscopes, cameras, light sources.
2. ethylene oxide (gas) and cold sterilisation (liquid) (uses oxidising agents e.g. peracetic acid / alkylating agents e.g. glutaraldehyde / chlorine-based agents.
3. Ethylene oxide is time consuming as need to wait for harmful gas to dissipate afterwards.
   not always available in first opinion practices.
   Cold sterilisation requires thorough rinsing as chemicals irritant to living tissues.

Question 27

1. Example of moist heat sterilisation?
2. Advantages of autoclave?
3. How does it work?
4. Best way to load autoclave and why?
5. What should be done regularly?

Answer 27

1. Steam autoclave.
2. Economical, non-toxic, reliable.
3. Pressure increases, raising temperature, air replaced by steam.
   – Gravity displacement - 13 minutes at 120C.
   – Pre-vacuum - 3 mins at 131C.
4. Plastic packs not stacked on top of each other. So steam can circulate properly.
5. Test of autoclave function.

Question 28

1. 2 types of sterile indicators?

Answer 28

1. Chemical – colour change on exposure to sterilising temperature.
   Biological – Heat resistant bacterial spores.

Question 29

1. Therapeutic antimicrobials.
2. Prophylactic antimicrobials.

Answer 29

1. Treatment of an established infection. Use beyond length of surgery until the infection is cured.
2. Use of antimicrobials with no infection present, with the aim of preventing one. Use immediately before the surgery, during and up to 48hrs post-surgery.

Question 30

Principles of using prophylactic antimicrobials in surgery.

Answer 30

Only use if:
- Risk of SSI high (think of the patient, pathogen, surgical factors).
- Consequence of infection would be catastrophic (e.g. ortho surgery).
Choose an appropriate antibiotic.
Tissue levels at surgical site should peak at time of incision.
ABX should be given IV (normally just before GA induction).
Give additional intra-op dose(s) only if necessary e.g. after 90 mins.
Normally don’t continue beyond surgery.

Question 31

What prophylactic antimicrobials do we use?

Answer 31

Bactericidal.
Spectrum of activity to be against the organisms likely to cause SSIs in that population.
Should remain at effective levels for 4-6hrs post-op.
Available in IV formulation in your practice.
Often will be cefuroxime (Zinacef) – 2nd gen cephalosporin. (effective against gram-positive bacteria, relatively poor against anaerobic, better than 1st gen cephalosporins against gram-negative facultative anaerobes (Enterobacter, klebsiella, E. coli).

Question 32

Surgical wound classification.
How does this classification help surgeons make decisions?

Answer 32

Clean
Clean-contaminated
Contaminated
Dirty

Classification is a significant determining factor in the risk of SSI and thus help decide whether we should use antimicrobials.

Question 33

1. How does a clean wound arise?
   – Is prophylactic antimicrobial use routinely warranted for this?
2. How does a clean-contaminated wound arise? – Is prophylactic antimicrobial use warranted for this?

Answer 33

1. In an elective, non-traumatic procedure, with proper aseptic technique and primary closure.
   – No, but may be considered if op >90 mins, or infection would be catastrophic.
2. In an elective, non-traumatic procedure, with proper aseptic technique and primary closure. But, entry is made to the GI, respiratory, or urogenital tract as part of the surgery. Or there is a minor break in sterility. – Depends on circumstances.

Question 34

1. How would a contaminated wound arise?
   – Prophylactic antimicrobials warranted?
2. How would a dirty wound arise?
   – Prophylactic antimicrobials warranted?

Answer 34

1. • Fresh traumatic wound.
     - Acute non-purulent inflammation.
     - Gross spillage from contaminated viscus e.g. GIT.
     - Major break in aseptic technique.
     – Often warranted.
2. • Traumatic wound with delayed treatment, devitalised tissue, faecal contamination and/or FBs.
     - Infected surgical site.
     - Purulent discharge.
     – Yes and classed as therapeutic, not prophylactic!
     Should be based on culture and sensitivity test.

Question 35

How to achieve asepsis in operating theatre?

Answer 35

Reduce traffic – ideally one-way traffic and limited number of doors.
Separate patient preparation area.
Only enter wearing appropriate surgical attire.
Regular cleaning and disinfection – minimise furniture and equipment and have adequate drainage.
Positive pressure ventilation – when theatre door opens, air flows out of theatre.
Have clean and dirty operating theatres – or order ops from clean to dirty.