The Operating Unit
provides a safe and controlled environment for the operative care of patients
undergoing diagnostic/ surgical procedures under anaesthesia and Per-operative
care including post procedure recovery.
Basic Requirements
- ·Occupancy: Standard occupancy of 5-8 persons at any given point of time inside the OT is considered.
- ·Equipment Load: Standard equipment load of 5-7 kW and lighting load of 1 kW to be considered per OT. For super speciality OT the equipment load can be taken as 7 – 9KW.
- Ambient temperature & humidity at each location to be considered while designing the system.
Requirements
– Super Specialty OT
1. Air Changes Per Hour:
- ·Minimum total air changes should be 20 based on international guidelines although the same will vary with biological load and the location.
- ·The fresh air component of the air change is required to be minimum 4 air changes out of total minimum 20 air changes.
- ·100 % outdoor ventilation air systems are not mandatory. If HCO chooses to have 100% fresh air system than appropriate energy saving devices like heat recovery wheel, run around pipes etc. should be installed.
- ·The supply & return air ducts must be of non-corrosive material.
- ·No internal insulation or acoustic lining must be done on ducts as they can become breeding grounds.
2. Air Velocity: The vertical down flow
of air coming out of the diffusers should be able to carry bacteria carrying
particle load away from the operating table. The airflow needs to be
unidirectional and downwards on the OT table. The air face velocity of 25-35
FPM (feet per minute) from non-aspirating unidirectional laminar flow
diffuser/ceiling array is recommended.
Positive Pressure:
There is a requirement to maintain positive pressure differential between OT
and adjoining areas to prevent outside air entry into OT. Positive pressure
will be maintained in OT at all times (operational & non-operational hours)
·Laminar flow boxes/diffusers should be
installed in the OT for supplying majority air and also majority return air
should be picked up 75-150 mm above floor level.
3. The minimum positive pressure
recommended is 2.5 Pascal (0.01 inches of water)
4. Outdoor Air intakes: The location of
outdoor air intake for an AHU must not be located near potential contaminated
sources like DG exhaust hoods, lab exhaust vents, vehicle parking area.
5. Air handling in the OT including air
Quality: Air is supplied through Terminal HEPA (High-efficiency particulate
arrestance) filters in the ceiling .The HEPA can be at AHU level if it not
feasible at terminal level inside OT. The minimum size of the filtration area
should extend one feet (i.e. 304.8 millimetres) on each side of the OT table to
cover the entire OT table and surgical team. The minimum supply air volume to
the OT (in cubic feet per minutes CFM) should be compliant with the desired
minimum air change.
6. Air Filtration: The AHU (i.e. air
handling unit) must be an air purification unit and air filtration unit. There
must be two sets of washable flange type filters of efficiency 90% down to 10
microns and 99% down to 5 microns with aluminium/ SS 304 frame within the AHU.
The necessary service panels to be provided for servicing the filters, motors
& blowers. HEPA filters of efficiency 99.97% down to 0.3 microns or higher
efficiency are to be provided .
7. Temp & RH for Super-specialty
OT: It should be maintained 21 C +/- 3 C
(except for Ortho for Joints replacement as 18 C +/-2 C) with corresponding
relative humidity between 20 to 60% though the ideal RH is considered to be
55%. Appropriate devices to monitor and display these conditions inside the OT
may be installed.
Requirements
– General OT
1. Air Change Per Hour:
· Minimum total air changes should be 20
based on international guidelines although the same will vary with biological
load and the location.
· The fresh air component of the air change
is required to be minimum 4 air changes out of total minimum 20 air changes.
2. Air Velocity: should be same as per
previous guide.
3. Positive Pressure: There is a requirement
to maintain positive pressure differential between OT and adjoining areas to
prevent outside air entry into OT. The minimum positive pressure recommended is
2.5 Pascal (0.01 inches of water).
4. Air handling/Filtration: It should be
same as previous. When not possible,
the OTs should be well ventilated with 2 levels of filtrations with
efficiencies as specified previously (pre and micro vee filters should be in
position at the AHU).
5. Temperature and Humidity: The temperature
should be maintained at 21C +/- 3 Deg C inside the OT all the time with
corresponding relative humidity between 20 to 60%. Appropriate devices to monitor and display
these conditions inside the OT may be installed.
OT
Construction:
a) The AHU of each OT should be dedicated one
and should not be linked to air conditioning of any other area for all OT
constructed.
b) Window & split A/c should not be used
in any type of OT because they are pure re circulating units and have
convenient pockets for microbial growth which cannot be sealed.
c) Paint- antibacterial, anti-fungal
d) OT door – automatic/ Hermitically
Sealed/Touch free (preferable)
e) General Lights – Clean room lights
f) Provision of safety against static
charge.
g) Separate power circuit for equipment
like Laser.
h) The anti-static flooring, walls and ceiling
should be non-porous, smooth, seamless without corners (coving) and should be
easily cleanable repeatedly. The material should be chosen accordingly.
Anti-static Flooring – seamless, including
skirting, should not be of porous stone as it absorbs moisture and could
be a source of bio-burden.
Maintenance
of the system
·During the non-functional hours
AHU blower will be operational round the clock (may be without temperature
control). Variable frequency devices (VFD) may be used to conserve energy. Air
changes can be reduced to 25% during non-operating hours thru VFD provided
positive pressure relationship is not disturbed during such period.
- Validation of system to be done as
per ISO 14664 standards and should include:
- Temperature and Humidity check
- Air particulate count
- Air Change Rate Calculation
- Air velocity at outlet of terminal filtration unit /filters
- Pressure Differential levels of the OT wrto ambient / adjoining areas
- Validation of HEPA Filters by appropriate tests like DOP (Dispersed Oil Particulate) /POA (Poly Alpha Olefin) etc.; repeat after 6 month in case HEPA found healthy.
Preventive Maintenance of the system: It is
recommended that periodic preventive maintenance be carried out in terms of
cleaning of pre filters, micro vee at the interval of 15 days. Preventive
maintenance of all the parts of AHU is carried out as per manufacturer
recommendations.
Credit: Sivakumar
Murugesan,Project & Accreditation Consultant
Medpoint Healthcare