Critical Room Design for Better Infection Prevention
Hospital Critical RoomDesign ▪ Types of Isolation Rooms ▪ Codes/Standards/References ▪ Design Criteria ▪ Design Considerations ▪ Design Examples ▪ Clean Room design and Standard
Types of Isolation Rooms Airborne Infection Isolation (AII) Rooms ❖ Used to reduce the spread of airborne infectious diseases (TB) from the patient in the AII Room to the rest of the hospital. ❖ Most common type seen in hospitals Protective Isolation/Environment Rooms ❖ Used to protect the patient (typically an immune suppressed patient) in the protective environment from common environmental airborne infectious microbes. ❖ Less common than AII Convertible Isolation Rooms ❖ Rooms that can be converted from an AII Room (negative) to a Protective Environment Room (positive) ❖ Out of date concept - not allowed by ASHRAE Standard 170 Combination AII/PE Rooms ❖ Used for an immune suppressed patient who has an infectious disease. ❖ Protects both patient and rest of the hospital. Contact Isolation Room ❖ Used for patients suffering from communicable disease that is not airborne ❖ This type of room is a standard patient room and should be treated as such. No special measures must be taken for design of the HVAC system.
Codes/Standards/References ▪ “Guidelines for Environmental Infection Control in Health - Care Facilities”, Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee (HICPAC), 2003 Codes: ▪ Illinois Administrative Code – will refer to as IDPH ▪ Title 77: Public Health Chapter I: Department Of Public Health ▪ Subchapter B: Hospitals and Ambulatory Care Facilities Part 250 Hospital licensing Requirements for HVAC: refer to Section 250.2480 Mechanical ▪ International Mechanical Code (IMC) - applicable to most suburbs City of Chicago Building Code Standard: ▪ ANSI/ASHRAE/ASHE Standard 170 – Ventilation of Health Care Facilities (2013) ▪ NFPA 101 Guidelines: ▪ Facility Guidelines Institute (FGI) Guidelines (2014) – for ventilation refers to ASHRAE Standard 170 – 2013
Airborne Infectious Isolation Room Design Step 1: Develop HVAC Design Criteria Temperature, humidity, airflow and pressurization requirements ASHRAE CDC Standard 170-2013 (incorporates CDC) IDPH • Temp/humidity – • 70F-75F – ability to not addressed maintain at all • 75F • Min 12 ach exhaust for times rooms constructed • 30% rh winter min,60% rh • 60%rh since 2001 summer max • 12 ach minimum total • Min 0.001”H 2 O pressure • 15 cfm per bed/ 10 cfm airflow/2 ach outside air differential to achieve per bedOA • All air exhaustedto airflow into room (this is • All air exhaustedto outside too low – need 0.01” wg) outdoors • Negative pressure • Airflow into room relative to adjacentspaces
Airborne Infectious Isolation Room Design Step 1: Develop HVAC Design Criteria Use most stringent of IDPH/ASHRAE Standard 170 Temperature : 70F to 75F Humidity: 30% rh winter min, 60% rh summer max 12 ach total/ 2 achOA Airflow: Negative to adjacent areas Pressure :
Differential Room Pressure Air moves to achieve pressure equilibrium. Consequently a room that is under positive pressure will have air moving out of it to equalize with the surrounding area. Conversely, a room under negative pressure will retain air in the space and draw air in from the surrounding areas. This differential in air pressure between spaces can be used to control airborne pathogens.
Airborne Infectious Isolation Room Architectural Design Considerations ➢ Ante room with hand wash sink (IDPH Section 250-2440) Note not required by FGI or ASHRAE ➢ One toilet room per AII room
Airborne Infectious Isolation Room Architectural Design Considerations ➢ AII room constructed To minimize leakage areas and allow for room pressurization • Walls – slab-to-slab • Ceilings – plaster or drywall • Self-closing doors (swing out for negatively pressurized spaces;swing in for positively pressurized spaces) with door sweeps • Finishes should be smoothand cleanable • Label room use(signage) • Seal all penetrations
Airborne Infectious Isolation Room Pressurization Design Considerations Min of 10% more EA Min ΔP between AII than SA but no less AII room negative to ante Permanently installed ΔP than 50cfm room and adjacent room/ante room monitoring device (ASHRAE) rooms/corridor - 0.01” wg negative to corridor • New tight construction- (ASHRAE) (ASHRAE) 200cfm to 300 cfm differential Provide provisions to change HVAC for normal patient care room use (IDPH only/different than ASHRAE)
Airborne Infectious Isolation Room Room Supply and Exhaust Design Considerations ➢ Ante room airflow: 10 ach (ASHRAE) ➢ Location of supply diffusers and exhaust grilles - CDC 2003 and ASHRAE Standard 170 disagree o CDC 2003: Supply above patient, exhaust low on wall o ASHRAE Standard 170 2008/2013: “Exhaust grilles or registers … shall be located directly above the patient bed on the ceiling or on the wall near the head of the bed…” o Designer may consider discussing discrepancy with hospital infection control. o If chose to supply above patient use non-aspirating laminar flow type diffusers
Airborne Infectious Isolation Room Other Design Considerations ➢ SA must be from AHU that has code-required filtration: Min MERV 7 prefilters and MERV 14 final filters (IDPH/ASHRAE) ➢ Exhaust air from AII/ante room/toilet room shall not mix with non-AII room exhaust (ASHRAE)
Diagram from CDC Guidelines
Airborne Infectious IsolationRoom Room HVAC Design Example ➢ Exhaust system: ➢ Design Calculation for 40m2 isolation room EA from AHII to maintain 12 ach: 350 cfm Toilet exhaust: 50 cfm EA from ante room to maintain 10 ach: 140 cfm Constant volume exhaust box to maintain EA / Total EA = 350 cfm + 50 cfm + 140 cfm = 540 cfm ➢ Supply system: • Isolation room Supply=EA isolation - 50 = 300 CFM Constant volume box to maintain total SA / Total SA = 300 cfm + 100 cfm = 400 cfm Reheat coil to provide space temperature control ACH= Q*60 Volume Q= Volume of air in CFM Volume= Volume of room in cubic feet
CONTROLS FOR CRITICAL ROOM CAN BE POSITIVE OR NEGATIVE PRESSURE
Room Pressure Monitors o Locate outside of anteroom door in corridor o Alarms visually and audibly if negative pressure is not maintained. o Tie-in alarm to building automation system o To avoid nuisance alarms, control to a higher point ΔP than to the ΔP at which the alarm is set • Control to 0.03” and alarm at 0.01”.
Airborne Infectious Isolation Room Central System Design ➢ Exhaust System • Locate exhaust fan outside, if possible • If exhaust fan is inside, use welded duct construction downstream of fan • Bag in/bag out prefilter/HEPA filter upstream of the exhaust fan • VFDs for the exhaust fan to adjust fan speed as filters load up • Locate fan discharge away from all intakes and above roof, if possible • Consider large exhaust system to serve multiple rooms instead of multiple smaller exhaust systems • Provide emergency power for fans
Bag In/ Bag Out Procedure
Airborne Infectious IsolationRoom Central System Design ➢ Supply System • Can supply from same AHU system that serves adjacent patient rooms • Must have Min MERV 7 prefilters and MERV 14 final filters (IDPH/ASHRAE) • Must be able to humidify to IDPH required 30% rh
Protective Isolation Room Design Step 1: Develop HVAC Design Criteria Use most stringent of IDPH/ASHRAE Standard 170 Temperature: 70F to 75F Humidity: 30% rh winter min, 60% rh summer max 12 ach total/ 2 ach OA Airflow: Positive to adjacent areas Pressure:
Protective Environment Room Pressurization Design Considerations Min of 10% more SA than Min ΔP between PE room Permanently installed ΔP PE room positive to ante EA but no less than 50 cfm room/ante room positive to and adjacent monitoring device (ASHRAE) • New tight construction- corridor (ASHRAE) rooms/corridor 200cfm to 300 cfm differential +0.01” wg (ASHRAE • Poorly constructed - 300cfm to 500 cfm Provide provisions to change H V A C for normal patientcare room use (IDPH only/different thanA S H R A E )
Combination Airborne Infectious Isolation/Protective Environment Rooms ➢ ➢
Clean Room Standard ISO -14644-1 USP 797
Critical room design for better infection prevention Standards for the design of ventilation system in operating rooms CONTENT Filtration system Speak peaker: r: Operation block planning Helena Hrastnik hhrastnik@klimaoprema.ae Construction requirements for operating rooms Interesting facts and Best practice
EU-DIN ▪ DIN 1946-4: 2018/06 Ventilation in buildings and rooms of health care STANDARDS AND GUIDELINES FOR THE DESIGN OF USA VENTILATION SYSTEM ▪ ASHRAE 2008 standard 170 IN OPERATING ROOMS Ventilation of health care facilities UK ▪ HTM 2025, HTM 03-01 Ventilation in health care premises
One goal to all Standards and Guidelines… …TO PROTECT THE OPERATING ROOM FROM HOSPITAL INFECTION
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