Basic Documentation

Newly constructed and renovated airborne infection
isolation patient rooms should be 0.01 in. WC
negative (-2.5 Pa) with respect to the corridor.
6
Differential Pressure Monitoring–To verify that the
required level of pressure differential maintained
between the infection isolation room and corridor,
visual indication of the direction of airflow is required
at the entry to the patient room
7
. This allows the
negative pressurization to be constantly monitored
and verified at the entry to the patient room. The
differential pressure monitor provides visual
indication of the direction of airflow to the healthcare
workers. It lets them know that the required room
pressurization is being maintained and also warns
them of any loss of the required differential pressure.
State building codes, may require room
pressurization to be monitored at the nurses station
by an auxiliary alarm panel to show individual room
alarm indication.
When a door is opened, a momentary loss in
differential pressure occurs as the door opens and
then closes. Therefore, differential pressure alarms
have an adjustable delay period to prevent nuisance
alarms during the time needed for normal passage
through the doorway and for the ventilation system
to restore the required differential pressure. Even
though a momentary loss of the differential pressure
occurs while a door is open, proper directional
airflow into the patient room is maintained and
airborne pathogens are kept from drifting outward
toward the doorway.
Differential pressure monitoring also provides
remote monitoring and provides alarm indication to
the building automation system (BAS), which allows
historical isolation room operation data to be
collected. If alarms are monitored by the BAS
Remote Notification application these alarms can be
monitored and assessed by infection control team.
The alarm monitoring process should include alarm
escalation procedures so corrective action can be
implemented and documented.
Room pressurization must be confirmed before a
patient is placed in an AII room, and checked daily
while the room is occupied
8
. The Room differential
pressure monitor documents room operation and
reduces the need for manual confirmation of room
Siemens Industry, Inc. Page 5 of 12
Document No. 149-903
6. Centers for Disease Control (CDC), December 2003,
Guidelines for Environmental Infection Control in Health-
Care Facilities, Table 6, p. 19
7. Centers for Disease Control (CDC), December 2003,
Guidelines for Environmental Infection Control in Health-
Care Facilities, p. 34
8. Ibid.
pressurization by use of visible smoke test.
However, smoke test verification of room airflow
direction must still be completed as part of normal
system maintenance. It is also important that HVAC
controls for the patient room be located outside of
the rooms so that access to the control devices will
not require service personnel to enter the patient
room.
Ventilation Rate for Infection Isolation Rooms–
Newly constructed and renovated infection isolation
patient rooms should receive a minimum of 12 air
changes per hour (ACH) and existing rooms should
have a minimum of 6 ACH
9
.
Ventilation Rate Effectiveness–Figure 2 shows a
graph of the time required for various
ACH rates to
remove given percentages (90%, 99%, and 99.9%)
of aerosols from a room. This data is taken from the
CDC Guidelines for Preventing the Transmission of
Tuberculosis in Healthcare Facilities.
010203040
50 60 70 80 90
20
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1
0
A
C
H
010203040
50 60 70 80 90
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MINUTES
99.9%
99.9%
90%
99%
90%
99%
Figure 2. Time to Remove Various Percentages
of Aerosols vs. Room ACH Rate.
Protective Environments
A Protective Environment (PE) is intended to protect
patients with immunocompromised systems from
contracting infectious diseases by aerosol
transmission. Immunocompromised is a condition in
which the immune system is not functioning
normally, leaving the patient in a permanent or
temporary state of increased susceptibility to
infection. In the broader term, immunosuppression
refers to restricted states with iatrogenic causes,
including causes that result from therapy for another
condition. Susceptibility to various infections is
determined by severity of immunosuppression and
9. Ibid, p. 36