OT’s have been divided into 3 categories:
- Super Speciality OT: Neurosciences, Orthopaedics, Joint Replacements, Cardiothoracic and Transplant Surgeries
- General OT: Ophthalmology, General Surgery, OBG & other routine Surgeries
- Day Care Centre: Here patient return home the same day and does not need to stay overnight
VENTILATION
It is on the principle that the direction of air flow is from the operation theatre towards the main entrance of the OT Complex.
- Air Changes per hour:-
- Total air changes should be between 20-30 based on international guidelines
- The Fresh air component of the air required is 20% i.e. Four air changes out of total 20 air changes
- 100% outdoor ventilation air system is desirable
- Air Velocity:
- The idea is that the vertical flow of air coming through the diffuser from the ceiling should drive particle load away from the operating site. The flow is unidirectional, downward, outward from the OT Table.
- The flow is at the rate of 25-35 FPM (feet per minute) from the Laminar Flow.
- Positive Pressure Gradient:
One has to maintain a positive pressure gradient in the OT complex in order to ensure that the air travels from the sterile zone to the outer zones and not vice versa. This positive pressure is to be maintained always even in operational or non operational hours.
- The pressure recommended is 2.5 pascals
- The air return should be picked up near the floor of the OT at around 75-150 mm from the floor level
- AHU should be located away from areas which can cause contamination like drainage pipes, sewers, DG Set exhaust etc.
- HEPA Filters (High Efficiency particulate Arrestance)
These Filters are installed in the laminar flow , diffusers in the ceiling or usually in the AHU’s depending on the design. The efficiency of these filters should be 0.3 micron or above.
- There are three levels of filtration done in AHU’s. First Level Filters at 10 microns, Second Level Filters at 5 microns and Hepa Filters at 0.3 micron or above.
- Temperature should be maintained 21C +-3C (except for ortho – Joint Replacement) which requires 18C +-2C.
- Relative Humidity between 20% to 66%, though the ideal RH is considered to be 55%
- Antibacterial and Antifungal paint to be used
- Automatic, Hermitically sealed door are preferred
- Antistatic flooring, non porous material walls, and seamless joints.
- Quality Validation System
- Temperature and Humidity Log
- Air Particulate Count report and proper documentation
- Air change rate calculation log
- Air velocity measurement log
- Pressure Differential readings
- Validation of HEPA Filters by DOP Test (Dispersed oil Particulate)/POAC (Poly Alpha Olefin) etc- every 6 months
- Cleaning of Filter of all types – every 15 days
Reference:
American Society & Healing, Refrigerating and Air-conditioning Engineer(ASHRAE)
NABG Guidelines