Biomedical Engineering Reference
In-Depth Information
of medical devices. Large devices, such as stretchers,
spare anesthesia machines, and X-ray equipment, must
be stored in accessible locations where they will not
clutter or obstruct hallways.
designed so that there is no recirculation of air from room
to room.
Adequate filtering is another important criterion of
the ventilation system. A hospital-grade high efficiency
particulate air (HEPA) filter is installed at the location
where the air is drawn in, to filter debris and to control
airborne infection. Hospital-grade HEPA filtration is
constructed with an air-intake grill to catch larger debris
such as leaves, seeds, and insects. Next is a layer com-
posed of fibers to remove smaller objects like dirt and
dust. Finally, a corrugated fine-mesh removes particles
such as pollen, dust, and viruses.
Other areas
Functional areas that also can be located in or near the
OR include dark rooms, conference areas, and locker
rooms.
Operating room facility
infrastructure
Electrical power distribution
The prevalence of electrical devices for the diagnosis and
treatment of patients has made electrical power distri-
bution one of the more important systems in modern
medical facilities. The nature of the OR environment
demands a particularly elaborate set of requirements.
Electrically powered devices surround the patient and
perform a wide range of vital functions. Therefore,
proper design and maintenance of the electrical power
system are essential, to ensure the safety of both the
patient and the clinician. As the need for a continuous
power is essential throughout a hospital, electrical sys-
tems must comprise at least two sources of power. The
typical primary power sources are public utility lines. To
provide for the continuous supply of power to the critical
areas of the hospital, an alternate, or emergency, source
of power is necessary. In the event of an interruption,
hospitals are required to have an in-house alternate
source of power, such as a generator.
The OR is densely populated with electrically
powered devices. Individual surgical suites must be
supplied with enough electrical wall outlets to
accommodate the equipment, and these outlets must be
in locations that are conveniently accessible to the clini-
cian. Wall outlets in a health care facility deliver power to
equipment using a three-wire configuration of hot, neu-
tral, and ground wires. The ground wire protects patients
and staff from electrical hazards by providing a low
resistance pathway to channel fault or leakage currents
away from an electrically powered device to ground.
Some surgical techniques and instrumentation bypass the
patient's body resistance, thus increasing the patient's
susceptibility to electrical energy from external sources.
Minimizing the electrical energy to which a susceptible
patient is exposed is prudent.
Although most equipment is designed to operate on
the same power requirements, the facility also must be
prepared to accommodate devices that require varying
power consumption. While most wall receptacles pro-
vide 115 volts, some electrical devices, such as lasers and
X-ray equipment, require 230 volts to operate.
The OR is a complex environment that requires precise
climate control and numerous utility services. The fol-
lowing is a list of utilities services that are present in an
OR. A description of each utility is included.
Climate control
The purpose of a heating, ventilating, and air-condition-
ing (HVAC) system is to provide and maintain environ-
mental conditions, including proper airflow, heating, and
cooling within a certain area or the entire hospital. Types
of HVAC systems include variable air volume, multizone
systems, displacement ventilation, and water-loop heat
pumps. An HVAC systemmainly consists of an air/water
supply system, filters, heating and cooling coils, com-
pressors, fans, motors, exhaust and evacuation systems,
air ducts, vents, and control mechanisms. It can provide
heat and ventilation to the entire hospital with provisions
for controls for individual zones (e.g., the OR), or each
zone can have their own HVAC system and associated
control. The control mechanism is an integral part of
a highly efficient HVAC system. The controls monitor,
display, and allow the user to regulate various parameters,
including temperature, pressure, and humidity. Precise
control over temperature and humidity is important in
the OR. For example, a clinician must be able to adjust
the temperature of the operating suite for surgical spe-
cialties such as pediatrics and orthopedics, where higher
room temperatures are desired in order to help maintain
patient temperature. Some cases, such as burn treat-
ments, require a higher humidity.
The OR requires specialized criteria for the ventilation
system as well. The surgical area must be replenishedwith
fresh air at regular time intervals time to maintain a safe
and sterile environment. A minimum of three air changes
per hour of outdoor air, and 15 total air changes per hour, is
required (AIA, 1996). A positive pressure must exist
between the OR and adjacent areas, to prevent the inflow
of contaminated air. The ventilation system also should be
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