Isolation Precaution (Part 2) Prof (Col) Dr RN Basu Adviser Quality & Academics Medica Superspecialty Hospital And Executive Director Academy of Hospital Administration, Kolkata Chapter Airborne Infection Isolation (AII) Room These rooms are for patients having an airborne communicable disease In this type of infection, patient is the source of infection The ventilation system functions as one of multi-levels of infection control system The purpose is to contain the infection within the room Protective Environment (PE) Room These rooms are meant for patients with weakened immune system These patients need protection against infectious airborne agents In this case it is the patient who must be protected from infectious microbials Also protection from opportunistic organisms that are not a threat to healthy individuals Combined AII/PE Rooms These rooms are for patients suffering from a weakened immune system and also having an air-borne communicable disease The ventilation issues involved is combination of both AII and PE room Contact Isolation The patients who are put in these rooms are not having communicable disease that is airborne Example of such cases are: Diarrhoea Draining wound Body lice and so on 1
Air-borne Infectious Isolation Room Arrangement Source: ASHRAE 10 Standard pressure room These are used for patients requiring contact or droplet isolation A standard room with normal air conditioning is appropriate A single patient room should have six air changes per hour Airborne Infection Isolation (AII) Rooms Required for patients requiring airborne droplet nuclei isolation These rooms provide a volume within which airborne particles are contained, diluted, and directed outside. AII rooms have two major ventilation design criteria: negative air pressure relative to all adjoining spaces, and an air distribution pattern within the room designed to reduce airborne infection 11 12 Location of AII locate isolation rooms away from stairwells, elevators, or any other floor-to-floor shafts. The reasons are: Pressure fluctuations in the shafts can affect the pressure differential of the isolation room and cause airborne infectious isolation (AII) rooms to go positive, or protective isolation rooms to go negative. The architect is responsible for floor plans and location of rooms, However, the hospital administrators should advise the architects An anteroom is not mandatory in AII rooms, but is highly recommended This is required to maintain pressurization and the air pattern, and minimize transfer of air with the corridor Within the isolation room goal of the HVAC system Is to establish an airflow arrangement that reduces exposure of uninfected people These people visit or work in the space 13 14 2
Supply air location above and near the doorway and/or near the exterior window with ceiling-mounted supply outlets. This arrangement controls the flow of clean air first to parts of the room where workers or visitors are likely to be, and then across the infected source into the exhaust. There is disagreement between CDC and ASHRAE Pressure differential between rooms should be no less than 2.5 pascals Install an en-suite bathroom The en-suite entrance should not be in the anteroom Supply air to the room does not have to be 100% outdoor air. However, supply air must be filtered at least to the levels of the general patient space Duct the exhaust directly to the outside discharging vertically at 10m/sec Locate duplex exhaust fans at a point in the duct system 15 16 Ensure supply air ducts are independent of the common building supply air system Supply air and exhaust systems to be of a constant volume system Fit a local audible alarm in case of fan failure Interlock supply and exhaust fans to shut down supply fan in the event of exhaust fan failure Rooms should be as air tight as possible with monolithic ceiling, well sealing penetration 17 A self-closing door to be installed with well fitting durable door seals Direction of door swing should be corridor to inside of the room Doors can be interlocked AII rooms shall have a permanently installed device and/or mechanism to constantly monitor the differential air pressure : between the room (when occupied by patients with a suspected airborne infectious disease) and the corridor, adjacent spaces of the room whether or not there is an anteroom 18 A local visual means shall be provided to indicate whenever negative differential pressure is not maintained When an anteroom is provided, the pressure relationships shall be as follows: the AII room shall be at a negative pressure with respect to the anteroom, and the anteroom shall be at a negative pressure with respect to the corridor. Should be connected with standby generator Label the room as a negative pressure isolation room Protective Isolation/Environment Room Used to protect patient (typically an immune suppressed patient) from airborne infectious microbes Example: Bone Marrow Transplant Oncology Haematology And similar rooms for any condition that leaves a patient immunocompromised Less common than AII 19 21 3
Design considerations for a PE room are similar to those for an AII room: room air pressure control positive pressure with respect to all adjoining spaces Door should open outside PE room should be at positive pressure of 2.5 pascals in relation to anteroom A unidirectional flow approach is recommended, Air is introduced at low velocity (100 fpm [0.5 m/s] or less) from ceiling-mounted, non-aspirating-flow diffusers with HEPA filters Although not mandatory with a PE room, an anteroom is recommended Air is exhausted at the floor level near the entrance to the room. The intent is to establish a vertically downward wash of clean air through the breathing zone of the patient, This picks up contaminants as the air passes through the lower portion of the room and out through the exhaust registers. 22 23 PE rooms require continuous monitoring of pressurization with alarms. A differential pressure indicator must be visible from outside the room. Positive-pressure status of the room must be validated and the controls tested so that room pressure cannot become negative relative to the environment. The supply fan must be on emergency power Positive air pressure gradient from the room to the ambient air should be maintained For this, remove less quantity of air than the supply system The en-suite be at a negative pressure with respect to the patient s room 24 A terminal HEPA filter should be provided in the terminal air inlet Positive pressure rooms may share common supply air systems PE rooms shall have a permanently installed device and/or Mechanism to constantly monitor the differential air pressure between the rooms This requirement is to be followed irrespective of whether or not there is an anteroom. 26 Convertible Isolation Room These rooms can be converted from an AII room to a Protective Environment room This is an out of date Concept This is not allowed by ASHRAE standard 170 2013 Not considered further Combined AII/PE rooms This is required for a patient who is immunocompromised and has a suspected or known respiratory disease, such as tuberculosis. An anteroom is mandatory in combined AII/PE rooms. Two options are available for room pressurization: the room is negative to the anteroom with the anteroom positive to the corridor, or the room is positive to the anteroom with the anteroom negative to the corridor. 27 29 4
Contact Isolation Room A contact isolation room is for patients suffering from communicable disease: Example Such as chicken pox,» It is not airborne. This type of room is a standard patient room and should be treated as such. No special measures is required to be taken for design of the HVAC system. ACH rate 12 per hour or 145 liters per second per patient, whichever results in greatest air quality At 12 ACH, the average air molecule travels around in the space for an average of 5 min before exiting Staff protection is afforded by minimizing the airborne concentration of infectious microorganisms Location of exhaust outlet over the patient bed, or on the wall behind the bed. 31 37 Number of isolation rooms required To calculate, collect following data prospectively in existing facility: Number of patient admissions with infections requiring isolation Duration of isolation required for each patient Seasonal or other trends of admission of infected patients Type of unit where patient isolation may be necessary 39 40 Converting an en-suite single bed room Minimum requirements to upgrade existing facilities: 1. Add clinical wash hand basin 2. Upgrade existing extract fan 3. Install transfer grille to en-suite 4. Observation window in corridor Converting a single-bed room without en-suite facility Three adjacent single-bed room may be converted into two single-bed room with en-suite facility The layout is shown next Source: HBN 04-01, Appx 1 41 42 5
Creating an en-suite single-bed room with ventilated lobby Suspended ceiling to be replaced with sealed monolithic ceiling Access to the patient room will be via the lobby through a single door There are two options Two existing single-bed room with one en-suite single-bed room with ventilated lobby with bed access through the lobby Minimum requirements 1. Add clinical wash hand basin 2. Provide suitable extract fan 3. Install Transfer grille to en-suite door 4. Observation window in corridor with integral privacy blinds 5. En-suite facility Source HBN 04-01 Appx 1 43 When due to space restriction access through lobby is not possible alternative access to be provided 44 Minimum requirements 1. Add clinical wash hand basin 2. Provide a suitable extract fan 3. Install transfer grille to ensuite door 4. Supply air 5. Pressure stabilizer 6. Observation window in corridor 7. Double door for personnel and bed access 8. Disposable apron dispenser 9. Upgrade ceiling to monolithic sealed ceiling 10. En-suite facility Source HBN 04-o1 Appendix 1 Converting a multi-bed bay An existing four-bed bay may be converted to provide two en-suite single-bed room In this design it is not possible to provide a normal observation window To provide observation: Fully glazed lobby and bed room door may be provided This can provide visibility from corridor Integrated privacy blinds or e-glass controllable from corridor and bed room to be provided 45 46 Minimum requirements 1. Clinical wash hand basin 2. Provide suitable extract fan 3. Transfer grille to ensuite door 4. En-suite facility 5. Doors to be fully glazed with integrated privacy blinds 47 48 6
Bibliography 1. ASHRAE 170-2013. Ventilation of Health Care Facilities. ANSI/ASHRAE/ASHE Standard 170-2013 2. Health Building Note 04-01, supplement 1. Isolation facilities for infectious patients in acute settings. Department of Health, UK 3. Victorian Advisory Committee. Guidelines for the classification and design of isolation rooms in healthcare facilities, 2007. 4. NHS. South Staffordshire. Isolation: Standard Operating Procedure 5. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 6. Guidelines for Design and, Construction of Hospitals and Outpatient Facilities FDG, American Institute of Architects, 2014 49 7