Ventilation @entro! Package aaa (Reyaitoh Anoumbiyh (Room Diaptey) (Waltmounted Room & Reference Protas} ROOM PRESSURE CONTROL Building room pressurization is a critical factor to monitor in a hospital as it can greatly affect the controllability of the environment. If the building pressure is allowed to become negative due to supply filters being loaded, supply fans running too slow, or return fans. running too fast, humid and dirty air can be drawn into the building through cracks and openings. This air is completely unconditioned and can provide several of the necessary ingredients to promote mold growth (e.g., moisture, more spores, and nutrients.) Building room pressure gradient is achieved by controlling the quality and quantity of intake and exhaust air, maintaining differential air pressures between adjacent areas, and designing patterns of airflow for particular clinical purposes.CLASS N — NEGATIVE PRESSURE ISOLATION ROOMS The basic principle of pressurization for microbial contaminant control is to ensure that air flows from less contaminated to more contaminated areas. Air in an open Class N room, for example, should flow from corridors INTO the isolation room to prevent the spread of airborne contaminants from the isolation room to other areas. The purpose of this design is to eliminate the spread of infectious contaminants and pathogens into the surrounding environment via the airborne route. Class N is applicable to all infection isolation rooms where the patients known to or suspected to have infections are placed. Supply Patient Room A+D=B+C NEGATIVE PRESSURE ISOLATION ROOM The schematic above shows HVAC air flow arrangement for class N rooms. An anteroom designed to provide an “air-lock” (no mix of air) between the infectious patient and the common space is placed adjacent to the patient room. The air would flow from the ante room to the isolation room. Pressure control is maintained by modulating the main supply and exhaust dampers based on a signal from a pressure transducer located inside the isolation room. Infection-Control and Ventilation Requirements for “All” RoomsUse AIA guidelines as minimum standards where state or local regulations are not in place for design and construction of ventilation systems in new or renovated health-care facilities. Recommended elements include: 1. Ensure that the airborne infectious isolation rooms are designed to maintain negative pressure. 2. Maintain continuous negative air pressure no less than (2.5 Pa [0.01 inch water gauge]) in relation to the air pressure in the corridor. This is accomplished via a separate exhaust system sized to remove at least 15% more air than that of the supply system. 3. Monitor air pressure periodically, preferably daily, with audible manometers or smoke tubes at the door (for existing All rooms), or with a permanently installed visual monitoring mechanism. 4. Provide ventilation to ensure >12 ACH for renovated rooms and new rooms, and >6 ACH for existing All rooms, when supply or exhaust air filters are at their maximum pressure drop. 5. The recommended air filtration for the class N, airborne infectious isolation rooms is MERV 14 rating air filters (90% dust spot test filters) on the supply side and HEPA (99.97% @ 0.3um DOP) on the exhaust side. 6. Recirculation of exhausted air is discouraged, from class N rooms. The exhaust air should be directed to outside, away from air-intakes and populated areas. However, where recirculation may be deemed acceptable in some circumstances, HEPA filters (99.97% @ 0.3ym DOP) capable of removing airborne contaminants on the supply side must be incorporated. 7. The disposal of effluents should not create a hazard to persons outside or the staff maintaining these systems. Where supplemental engineering controls for air cleaning are indicated from a risk assessment of the “All” area, also install Ultraviolet Germicidal Irradiation (UVGI) units in the exhaust air ducts of the HVAC system to supplement HEPA filtration. For example in TB clinics, the air is often HEPA filtered10. 14. 15. 16. and sometimes given UVGI exposure before exhausting to the outside, though the reasons for this are primarily because of litigation concerns and not based on any known realities. Consider UVGI fixtures on or near the ceiling to irradiate upper room air. Note that UVGI, may be used to augment HEPA filters, but cannot be used in place of HEPA filters, as their effectiveness on airstreams is limited. The supply air should be located such that clean air is first passed over the stafffother occupants and then to the patient. Air distribution should reduce the staff's exposure to potential airborne droplet nuclei from infectious patients, accounting for the positions of the staff and the patient, and the procedures undertaken in the isolation room. Insider patient room, the supply air should be from the ceiling diffuser located al the perimeter near to the entry and the exhaust air should be drawn at lower levels approximately 6 inches above the floor in the room. . Exhaust air ducts should be independent of the building’s common exhaust air system to reduce the risk of contamination from back draught. . Locate the exhaust fan at a point in the duct system that will ensure the duct is under negative pressure throughout its run within the building. . The makeup air intakes should be located so that no contaminated air from nearby exhaust stacks or any sources of air contaminants is drawn into the makeup air system. Ensure supply air ducts are independent of the building's common supply air system. If sharing of supply ducts with other isolation rooms is unavoidable, provide the ducts with terminal HEPA filters (or other failsafe back draught prevention system). Install a high efficiency bag filter as a pre-filter to protect the HEPA filter. Design the supply air and exhaust systems to be of a constant volume system. Variable air volume (VAV) systems are NOT recommended. A monitoring system should be provided to signal any malfunction of thesupply/exhaust air system. Consider differential low -pressure instrumentation in a Prominent location outside the room along with a local audible alarm in case of supply/exhaust failure. 17. Ensure that rooms are well-sealed for better maintenance of pressure gradients that will also eventually reduce load on the air handling plant. Ensure air tightness by * Properly constructing windows, doors, and intake and exhaust ports * Maintain plasterboard ceilings that are smooth and free of fissures, open joints, and crevices * Sealing all penetrations on the walls above and below the ceiling * Monitoring for leakage and making any necessary repairs 18. Install self-closing devices on all ‘All’ room exit doors considering the direction of door swing in relation to room pressure 19. Provide a staff hand-wash basin in the anteroom and include personal respiratory protection for persons entering these rooms and for staff who lack immunity to airborne viral diseases (e.g., measles or varicella zoster virus [VZV] infection). 20.Do not use a room with a through-the-wall ventilation unit unless It can be demonstrated that all required ‘All’ engineering controls are met. 2 . Maintain backup ventilation equipment (e.g. portable units for fans or filters) for emergency provision of ventilation requirements for All rooms, and take immediate ‘steps to restore the fixed ventilation system. 22. Label the area as being a negative pressure isolation room. Emergency Rooms and Reception Areas In public areas of a health care facility such as an emergency room, reception and waiting areas, persons with undiagnosed active infection can come in contact with and infect others prior to examination and treatments. The likelihood of airborne contaminants leaving these rooms is reduced by keeping these rooms under NEGATIVEpressure, relative to surrounding areas. Air is exhausted from these rooms either directly to the outside or through high efficiency particulate air (HEPA) filters. CLASS P — POSITIVE PRESSURE ISOLATION ROOMS Class P - positive pressure isolation rooms are set at positive pressure relative to ambient pressure, meaning that air flow must be from the “cleaner” area towards the adjoining space (through doors or other openings). This is achieved by the HVAC system providing more air into the “cleaner” space than is mechanically removed from that same space. Class P is applicable to all protective environments housing severely neutropenic and immuno-suppressed patients. Exhaust A=B+C+D POSITIVE PRESSURE ISOLATION ROOM In the schematic diagram above an airlock or anteroom is provided adjacent to the Patient room. For a positive pressure room, air would flow from the isolation room to the anteroom and than to the corridor. Pressure control is maintained by modulating the main supply and exhaust dampers based on a signal from a pressure transducer located inside the isolation room. Infection Control and Ventilation Requirements for PE rooms Use AIA guidelines as minimum standards where state or local regulations are not in place for design and construction of ventilation systems in new or renovated health-care facilities. Recommended elements include:10. Ensure that the protective environment room is designed to maintain positive pressure. Maintain positive room air pressure (22.5 Pa [0.01-inch water gauge]) in relation to the corridor. Ideally it should be >8 Pa (0.03 inch-water gauge). Ventilate the room to maintain > 12 ACH or 145 liters per second per patient (whichever results in the greatest air quantity), when the supply air filter is at the maximum pressure drop. Class P rooms can be either 100% fresh air or can use recirculated air usually a 60/40 mix of outdoor air/recirculated air. As rule of thumb, air pressure should be maintained positive with respect to any adjoining rooms by supplying 10 to 15% excess air. The recommended air filtration for the class P, protective rooms is HEPA (99.97% @ 0.3m DOP) on the supply side and NO filtration is needed on the exhaust side. The HEPA filter could be centrally located at the air handling unit or point-to-use HEPA filters may be used. A terminal HEPA filter at the point of use is recommended. UVGI systems are sometimes used in conjunction with HEPA filters. When ultraviolet germicidal irradiation (UVGI) is used as a supplemental engineering control, install fixtures 1) on the wall near the ceiling or suspended from the ceiling as an upper air unit; 2) in the air-return duct of an ‘All’ area; or 3) in designated enclosed areas or booths for sputum induction. The supply air should be located such that clean air is first flows across the patient bed and exits from the opposite side of the room. Air distribution should reduce the patient's exposure to potential airborne droplet nuclei from occupants. Positive pressure rooms may share common supply air systems. Differential pressure indication device should be installed to permit air pressure readings in the rooms and provide a local audible alarm in case of fan failure. Ensure that rooms are well-sealed for better maintenance of pressure gradients that will also eventually reduce load on the air handling plant. Ensure air tightness by* Properly constructing windows, doors, and intake and exhaust ports * Maintain plasterboard ceilings that are smooth and free of fissures, open joints, and crevices * Sealing all penetrations on the walls above and below the ceiling * Monitoring for leakage and making any necessary repairs 41. Maintain airflow patterns and monitor these on a daily basis by using permanently installed visual means of detecting airflow in new or renovated construction, or by using other visual methods (e.g., flutter strips or smoke tubes) in existing PE units. Plan for automatic documentation of the monitored results. 12. Install self-closing devices on all room exit doors in PE rooms. All emergency exits (e.g., fire escapes, emergency doors) in PE wards should be kept closed (except during emergencies) and equipped with alarms. 13. Do not use laminar air flow systems in newly constructed PE rooms. 14. Do not use a room with a through-the-wall ventilation unit as PE room. 15. Install an ensuite bathroom along with a staff hand-wash basin in the anteroom. 16. Label as a positive pressure isolation room. Infection-Control and Ventilation Requirements for Operating Rooms The room pressure requirement for operating rooms is similar to PE rooms with following exceptions: 1. Maintain positive-pressure ventilation with respect to corridors and adjacent areas; maintain >15 ACH, of which >3 ACH should be fresh air. 2. Filter all recirculated and fresh air through the appropriate filters, providing 90% efficiency (dust-spot testing) at a minimum. 3. In rooms not engineered for horizontal laminar airflow, introduce air at the ceiling and exhaust air near the floor. 4. Do not use ultraviolet (UV) lights to prevent surgical-site infections.