This ppt is about operation theatre air filteration and asepsis in the OT

1. THEATRE DESIGN AND
VENTILATION
DR.LOKESH SHAROFF
Orthopaedic surgeon, Mumbai, India

2. CONCEPT
• It was first introduced by SIR JOHN CHARNLEY

3. ZONES IN THEATRE
OUTER ZONE – rest of the hospital outside the
theatre complex
CLEAN ZONE – theatre complex outside the
operating area
ASEPTIC ZONE – Operating area
DISPOSAL ZONE – Separate exit for
contaminated / used linen and instruments

4. REQUIREMENTS
AIR DELIVERY SYSTEM
AIR FILTERATION SYSTEM
TEMPERATURE CONTROL
HUMIDITY CONTROL

5. TEMPERATURE CONTROL
- Ideal working temperature is 19-20 * C – to
minimize perspiration
- But causes pt. hypothermia
- PT. body temp. should be 24-26 * C TO AVOID
HYPOTHERMIA

6. HUMIDITY CONTROL
- Should be around 40-60%
- Fastest death of organisms occur at 50%
humidity

7. AIRBORNE PARTICLES
- Measured as BCP/MM3 – Bacteria carrying
particles OR
CFU/MM3 – Colony forming units
- Each person emits 10k cfu/min at rest and 50k
cfu/min with activity
- This is reduced in SCRUBS to 140-830 cfu/min
with fask mask and caps.

8. AIRBORNE PARTICLES
- CONVENTIONAL AC (well maintained)- gives 50-
500 cfu/mm3
- All particles are not viable – viable : non viable
ratio is 1:1000
- Smallest particle in theatre seen in bright light is
12 microns
- Smallest particle that can carry bacteria is 4-5
microns

9. AIR FILTERS- 4 LEVELS
- ROUGHING FILTERS
removes Large particles and also protects
sensitive final filters
- PREFILTERS
should be 95% efficient
- FINAL FILTERS
should be 95% efficient with a particle size of 3
microns
- HEPA FILTERS
should be 99.97% efficient with a particle size of
0.3 microns

10. HEPA FILTERS
- Each hepa filter has a manometer attached to
it to measure the amount of resistance to
filteration for clogging purposes.

11. TYPES OF VENTILATION
High velocity air flow
- high speed jets towards operating table
- high speed air at periphery
Laminar air flow
- horizontal
- vertical

12. CONVENTIONAL WALL DIFFUSER

13. - Produces plenum
- No control of air over operating area
- Upto 500 bcp/mm3 – not acceptable for
operation theatres

14. HIGH VELOCITY AIR JET

15. - Jets increase air turbulence
- Flow at 0.6 m/s
- Jets may not point at right place and may
dessicate the wound

16. Vertical laminar flow
- Room within a room principle
- Air is passed through hepa filters from ceiling
downwards
- Flow at 0.3 m/s
- entrainment can happen by moving personnel

17. Horizontal laminar flow
- Forms part of a wall
- Easy to install
- Movement across it will cause uncontrollable
turbulence
- adequate clean zone is not possible

18. PERIPHERAL LAMINAR

19. CONVENTIONAL LAMINAR

20. Vertical laminar with canopy and side
panels
- Canopy – to overcome peripheral entrainment
- side panels – extend down to floor to within
20cms from floor
- very successful – 10 bcp/m3

21. Without side panels

22. - Peripheral entrainment air 0.6 m/s
- Higher energy consumption
- movement causes deflection of contaminants

23. EXPONENTIAL AIR FLOW

24. - Trumpet shaped air flow
- Downward and radially outward flow of air
- fliteration down to 1 micron
- Trays can be positioned even upto ½ m outside
the actual canopy

25. STANDARDS IN AIR FLOW
- Direction of air flow shall be under positive
control
- max. viable organisms should be not more
than 1 cfu/mm3
- ULTRA CLEAN ZONE – is less than 10 cfu/mm3

26. AIR CHANGES
- ATLEAST 20-40 AIR CHANGES PER HOUR
- Pressure gradient should be 1.3-2.5mm h2O
(more pressure causes rapid drying of the
wound)

27. AIR QUALITY CONTROL
- Done by CASTELLA SLIT SAMPLER

28. WATER SUPPLY IN OT
- Tanks and pipes – regular inspection for
leakages
- Bore well water should be avoided as far as
possible
- tanks and containers should have covers/lids to
protect from dust
- water sterilised by ultraviolet radiation

29. ANTIBIOTIC PROPHYLAXIS
- CHOICE OF AGENT
Active against comon pathogens
Take into account drug allergy and sensitivity
cefazolin/cefotaxim preferred-long duration
clinda/vanco in penicillin allergy pts.
Modification for pre-existing cultures
if already on abx – then continue same

30. ANTIBIOTIC PROPHYLAXIS
- TIMING
Within 15-60 mins prior to incision
Vanco should be given 2 hrs before
- Infusion should complete before incision

31. ANTIBIOTIC PROPHYLAXIS
- DURATION
Further dose efficacy is doubtful
Max 24 hrs if only prophylatic
intra-op – repeat if length of sx more than half
life of drug
repeat dose if blood loss >1500ml
not to continue abx till drain removal

32. ANTIBIOTIC PROPHYLAXIS
- RISKS
- PENICILLIN ALLERGY
- ANAPHYLAXIS
- ABX ASSOCIATED DIARRHOEA
- CLOSTRIDIUM DIFFICLE INFECTION
- ABX RESISTANCE
- MULTI-RESISTANCE CARRIAGE – SCREENING
SHOULD BE DONE IN HIGH RISK CASES

33. THANK YOU
*Pictures taken from journal of orthopedics today