Facilities Quality Service
ISOLATION ROOMS UPDATE
SWITCHABLE NEGATIVE/POSITIVE PRESSURE
ISSUE:
Switchable Isolation rooms that can be set to function with either negative or positive
pressure rooms.
DISCUSSION:
The VA HVAC Design Criteria allowed an isolation room (negative pressure) to be used
as a reverse isolation room (positive pressure) through a selector switch, which would
reset exhaust controls to achieve this. The 1999 ASHRAE Applications Handbook,
Chapter 7, Health Care Facilities, page 7.7, Infectious Isolation Unit recommended
against this approach "Switchable isolation rooms (rooms that can be set to
function with either positive or negative pressure) have been installed in many
facilities. AIA (1996) and CDC (1994) have, respectively, prohibited and
recommend against this approach. The two difficulties associated with this
approach are (1) maintaining the mechanical dampers and controls required to
accurately provide the required pressures, and (2) that it provides a false sense
of security on the part of staff who think that this provision is all that is required
to change a room between protective isolation and infectious isolation, to the
exclusion of other sanitizing procedures". Therefore, VA HVAC Design Criteria is
being amended to comply with this recommendation.
RECOMMENDATIONS:
1. Provide negative pressure isolation rooms, located and designed as per facility
needs, VA space criteria, and VA facilities standards. Rooms shall be non-
switchable.
2. Provide positive pressure (reverse isolation) rooms where specifically requested by
VAMC staff during the project design process. Rooms shall be non-switchable.
3. Implement these recommendations on all future projects, and projects currently
under design.
4. For projects under construction: Review VAMC requirements; status of
construction; and cost implications of recommended changes. Make changes that
are fiscally responsible and meet the needs of the VAMC staff.
(over)
16 May 2001
FM-181A-DA-108
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