Development of air-conditioning and artificial lighting has made possible very comfortable operating environment for depending upon windows for light is no more the optimum conditions of temperature; humidity lighting level can be controlled by mechanical means far better.
Lighting:
The surgeon’s requirement for light is that it should be powerful, cool, shadow less, and capable of penetrating to the bottom of deep cavities.
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An emergency lighting system which comes into operation automatically is also necessary in operation theatres to enable work to continue without a break if the mains supply fails.
Electrical outlets:
All electrical outlets should be “sparkles” fittings and be placed 5 feet from the floor, to be above the level of a possible concentration of inflammable anaesthetic gases.
This is necessary even though a good ventilation system can reduce the concentration of explosive gases and adequate humidity reduces static.
Sufficient number of plug points has to be catered for, for the various electrical/electronic gadgets used in a modern operating room. Minimum six outlets are suggested, at least two of which should be for power equipment of 15 Amp rating.
Air-Conditioning in OT Suite:
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Full air-conditioning with filtered air supply is a necessity in operation theatres which tends to generate a need for greater floor to ceiling height than in other hospital departments.
While perceptible air movement may be desirable in operating rooms for the surgical team, draughts, particularly at the level of the operating table, must be avoided.
The air speed at which air movement becomes perceptible rises with temperature, and air-conditioning systems enable the rate of input of air to be related to its temperature in order to provide comfortable conditions.
Air Intake:
Studies on positioning of the air intake show that samples of air taken at street level, at roof level and in the wards show that much advantage is to be derived from placing the intake at or above roof level.
Airflow:
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Positive air pressure has to be provided at the aseptic core which is ideally met with 16-18 air changes per hour, and gradually tapering off to 12 changes per hour at the non sterile areas.
In the modern operating room, laminar airflow system with side vents and exhaust system is the ideal. In the laminar airflow system, air velocity varies at 50 feet per minute at the foot level to 75 feet per minute at table height to 150 feet per minute at the ceiling level.
High efficiency particulate air (HEPA) filters used in the system provide the highest level of air sterility by filtering out participate matter of up to 0.3 micron which excludes almost all known sizes of micro-organism.
HEPA filter:
It is a dry type filter with a rigid casing enclosing the full depth of accordion type filter pleats.
This is throwaway, non reusable filter which is to be discarded after its recommended lifespan filters remove 99.9 per cent of airborne particles which include dust, pollen, mold and bacteria of up to 0.3 micrometers (pm).
Performance testing of HEPA filters is carried out by measuring the airflow resistance under test conditions only in a filter-testing facility using approved particle generating materials.