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This ppt is about operation theatre air filteration and asepsis in the OT
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THEATRE DESIGN AND VENTILATION
DR.LOKESH SHAROFFOrthopaedic surgeon, Mumbai, India
CONCEPT
• It was first introduced by SIR JOHN CHARNLEY
ZONES IN THEATRE
OUTER ZONE – rest of the hospital outside the theatre complexCLEAN ZONE – theatre complex outside the operating areaASEPTIC ZONE – Operating areaDISPOSAL ZONE – Separate exit for contaminated / used linen and instruments
REQUIREMENTS
AIR DELIVERY SYSTEM
AIR FILTERATION SYSTEM
TEMPERATURE CONTROL
HUMIDITY CONTROL
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
HUMIDITY CONTROL
- Should be around 40-60%
- Fastest death of organisms occur at 50% humidity
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.
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
AIR FILTERS- 4 LEVELS- ROUGHING FILTERS
removes Large particles and also protects sensitive final filters
- PREFILTERSshould be 95% efficient
- FINAL FILTERSshould be 95% efficient with a particle size of 3 microns
- HEPA FILTERSshould be 99.97% efficient with a particle size of 0.3 microns
HEPA FILTERS
- Each hepa filter has a manometer attached to it to measure the amount of resistance to filteration for clogging purposes.
TYPES OF VENTILATION
High velocity air flow - high speed jets towards operating table - high speed air at periphery
Laminar air flow - horizontal - vertical
CONVENTIONAL WALL DIFFUSER
- Produces plenum- No control of air over operating area- Upto 500 bcp/mm3 – not acceptable for operation theatres
HIGH VELOCITY AIR JET
- Jets increase air turbulence- Flow at 0.6 m/s- Jets may not point at right place and may dessicate the wound
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
Horizontal laminar flow
- Forms part of a wall - Easy to install - Movement across it will cause uncontrollable turbulence- adequate clean zone is not possible
PERIPHERAL LAMINAR
CONVENTIONAL LAMINAR
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
Without side panels
- Peripheral entrainment air 0.6 m/s- Higher energy consumption- movement causes deflection of contaminants
EXPONENTIAL AIR FLOW
- 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
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
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)
AIR QUALITY CONTROL
- Done by CASTELLA SLIT SAMPLER
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
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
ANTIBIOTIC PROPHYLAXIS
- TIMING Within 15-60 mins prior to incision Vanco should be given 2 hrs before
- Infusion should complete before incision
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
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
THANK YOU
*Pictures taken from journal of orthopedics today