Core Curriculum on Tuberculosis, 2000
Infection Control in Health Care Settings
The second level of the hierarchy is the
use of engineering controls to prevent the spread and reduce the
concentration of infectious droplet nuclei. Engineering controls
are based primarily on the use of adequate ventilation systems;
these may be supplemented with high-efficiency particulate air (HEPA)
filtration and ultraviolet germicidal irradiation (UVGI) in high-risk
areas. These strategies are designed to reduce the concentration
of infectious droplet nuclei in the air, prevent the dissemination
of droplet nuclei throughout the facility, or render droplet nuclei
noninfectious by killing the tubercle bacilli they contain.
Inpatient Settings. In isolation
rooms, ventilation systems are necessary to maintain negative pressure
and to exhaust the air properly. Isolation rooms should be monitored
daily when in use to ensure the negative pressure is maintained.
Isolation room doors should be kept closed, except when patients
or personnel must enter or exit the room, in order to maintain negative
pressure. Ventilation systems can also be designed to minimize the
spread of TB in other areas of the health care facility.
HEPA filters can be used in ventilation systems to remove droplet
nuclei from the air. These filters can be installed in ventilation
ducts to filter air for recirculation into the same room or recirculation
to other areas of a facility. The effectiveness of portable HEPA
filtration units has not been adequately evaluated. All HEPA filters
must be carefully installed and meticulously maintained to ensure
UVGI, or ultraviolet lighting, may kill M. tuberculosis contained
in droplet nuclei. Because exposure to ultraviolet light can be
harmful to the skin and eyes, the lamps must be installed in the
upper part of rooms or corridors or placed in exhaust vents.
Outpatients settings. In outpatient settings, such
as medical offices, that provide care to populations at high risk
for TB, the use of engineering controls may be appropriate.