Basic Documentation

Figure 1. Layout of Infection Isolation Patient Room
Figure 1 shows a diagram of the room arrangement
and HVA
C design for an infection isolation room.
The supply and exhaust air locations are chosen to
promote maximize air mixing and to optimize airflow
away from the healthcare worker towards the
patient. Supply air enters the patient room through a
Group A or Group E diffusers. The best location for
the supply diffuser is located in the ceiling at the foot
of the patient’s bed and the exhaust air on the wall
near the floor at the head of the bed.
Room Exhaust–While the exhaust air from infection
isolation rooms must be discharged outside of the
building, the guidelines listed at the beginning of this
document do not specifically require the exhaust to
be High Efficiency Particulate Air (HEPA) filtered.
5
However, HEPA filtering should be implemented if
unfiltered exhaust air might pose a hazard to
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Document No. 149-903
5. A HEPA filter will retain a minimum of 99.97% of aerosols
above 0.3 microns in diameter (0.3 millionth of a meter). This
will filter out all bacteria and most viruses. However it will not
stop chemical fumes or infectious prions. More information
on HEPA filters and their performance can be found on the
following Web site:
http://www.arche.psu.edu/iec/abe/wjkfiltr.html
persons, other buildings or might be re-entrained
into the building fresh air intakes. In most instances,
one or more of these potential scenarios is likely;
therefore, incorporating HEPA filters on the exhaust
is usually warranted.
Infection Isolation Room Pressurization–The
patient room must be maintained at a negative
pressure with respect to the corridor. This is
accomplished by exhausting a greater amount of
airflow from the combination of patient room and
toilet room than the amount of supply airflow
provided. The greater negative pressurization
created in the patient room ensures that airflow will
move from the corridor into the patient room. The
supply air diffuser location, the patient room exhaust
location, and the negative room pressurization
arrangement all combine to maintain a directional
room airflow that minimizes the likelihood that
infectious aerosols will travel from the patient to the
healthcare personnel and visitors.