AIRBORNE INFECTIOUS DISEASE MANAGEMENT • PREPARED BY THE MINNESOTA DEPARTMENT OF HEALTH
Environmental
controls
3
9
Introduction
1
Principles of airborne
infectious disease
management
2
TNPI
Temporary
Negative
Pressure
Isolation
Discharging
air to return
air system
Portable
anteroom
13
Surge
capacity
16
Appendix
20
FIGURE 9
A return grille
adapter.
Turn HEPA machine
on and adjust flow
Once the flex duct is connected to
the window template and the HEPA
machine, the machine should be
turned on.
Adjust the flow on the output until
the desired pressure differential of
negative 2.5 Pa (pressure in corridor
is greater than pressure in patient
room) is reached. Increasing the flow
will increase the pressure differential,
and decreasing the flow will decrease
the pressure differential.
The pressure differential should be
measured with a hand-held digital
pressure gauge. The pressure
should be monitored daily.
Additional Notes for
Discharging Air to
Return Air System
• You must be careful when
exhausting additional large volumes
of air through the return air system.
• When no longer needed,
the HEPA filter and flex duct
should be wiped down with
a hospital-approved disinfectant.
• HEPA filters can also be used
to enhance dilution ventilation.
Refer to Appendix E, “Using
a HEPA Filter for Dilution
Ventilation” on page 26 for
a discussion and example of
dilution ventilation.
FIGURE 11
This return
duct must
be sealed to
prevent pulling
air from return
air system.
Select
a room
You should choose a room to set up
TNPI. The HEPA machine should be
set up in advance to placing the
patient with a suspected airborne
infectious disease in the room.
If possible, select a room without
transfer grilles. If no such room
exists, completely seal the grilles
to promote negative pressure.
Attach flex duct
adapter to desired
return grille
Next, attach flex duct adapter to
desired return grille. Ideally, if the
return is low, connect the flex duct
here. However, most returns are high
on the wall or ceiling and these can
be connected in the same way.
It is important to provide a tight
seal between the flex duct and
the adapter as well as between the
adapter and the return grille.
(FIGURE 9)
Generally, it is easy to differentiate
between a supply grille and return
grille. If you are not sure, you can
use a smoke stick to check
airflow direction.
Set up HEPA
machine and flex duct
Connect the flex duct to return grille
adapter and HEPA machine. (FIGURE 10)
FIGURE 10
A return grille adapter with flex
duct attached.
Seal remaining
air grilles
To prevent pulling air from return air
system, additional exhaust/return
grilles should be sealed with tape.
(FIGURE 11)
Most rooms have only one supply,
a return grille, and one bathroom
exhaust. 100% of bathroom
discharge is exhausted outside,
so no extra consideration is required.
If there is more than one return grille,
which is uncommon, the additional
grille(s) should be sealed. A sheet
of plastic or cardboard can be used
provided that the edges are
completely sealed with tape.
AIRBORNE INFECTIOUS DISEASE MANAGEMENT • PREPARED BY THE MINNESOTA DEPARTMENT OF HEALTH