To meet the performance level required for treating immunosuppressed patients, the use of a horizontal unidirectional flow is required.
The trajectory of the airflow should touch the patient first and then the hospital staff before being returned, so as to prevent the patient from being contaminated by the staff who, in this way, are always operating downstream of the patient’s breathing zone. The filtering diffuser takes up the whole wall at the head of the bed. The air emitted by the diffuser crosses through the area occupied by the patient and exits through the door located at the end of the patient’s bed, which is fitted with micro-perforated panels, to allow the air to pass through. The air flowing through the door, with the aim of enveloping any staff about to enter the isolation room, thereby creating a contamination barrier, is then directed towards the ventilation system’s
In this configuration, the whole area occupied by the patient is ventilated with air filtered through HEPA H14 filters.
During the daytime, operations in the room take place amidst an airflow rate that is maintained at 0.36 m/s in the room section with noise levels under 48 dBA.
During night-time conditions, the airflow rate is reduced so as to reduce the noise levels, taking the average speed to 0.15 m/s which is equal to 147 vol/h.
The air processing unit for the air supplied into the room is composed of:
- Wall-mounted filtering diffuser;
- Exhaust grille to extract the recirculated air from the filter zone;
- A sensitive cooling coil to remove the thermal loads produced by the recirculation fans;
- Exhaust silencer;
- Ventilating unit;
- Inlet silencer.
The filtering diffuser that covers the whole wall is composed of a frame in AISI 316L stainless steel, whose components are sealed and airtight and the plenum is located behind the wall and made of the appropriately treated masonry. The surface from which the air is emitted is comprised of HEPA H14 filters, pursuant to EN 1822, fitted with a perforated plate flow equaliser. The wall also includes all trunking for medical gas connections, electrical connections and for the bedhead light.
To reduce the risk of contaminating the patient during normal practice, all items to be used by the patient are passed through a pass-through hatch fitted with unidirectional airflow and germicide UV lamps to sterilise them; this hatch is located so that the patient can remove the items from it when seated on the bed.