Encyclopedia of Health and Medicine

oxygen therapy 217
components, an emitter and a tiny computer chip.
The emitter is a small device that fits over the fingertip
or on the EAR lobe. It projects beams of red
and infrared light, which pass through the tissue
to a sensor on the other side. The volume of blood
in the tissue at systole (peak contraction of the
HEART) is greater, resulting in more light being
absorbed than with the lesser volume of blood in
the tissue at diastole (relaxation of the heart). The
oximeter’s computer chip measures this difference
and uses it to mathematically calculate the percentage
of oxygen the hemoglobin carries.
See also OXYGEN–CARBON DIOXIDE EXCHANGE; OXY-
GEN THERAPY.
oxygen therapy The administration of oxygen
via nasal cannula, face mask, endotracheal tube
(tube inserted into the THROAT), or transtracheal
catheter (small tube surgically placed through the
outside of the throat into the TRACHEA). Oxygen
therapy delivers oxygen at a percentage higher
than that of normal air, which is 21 percent oxygen
at sea level. Oxygen therapy can deliver oxygen
from about 25 percent to 100 percent. This
boosts the OXYGEN SATURATION of the BLOOD, which
becomes necessary when the LUNGS cannot adequately
diffuse oxygen into the blood or the HEART
cannot circulate oxygenated blood at a level that
meets the body’s needs.
Oxygen is highly flammable. Do not
smoke, have an open flame, or use electrical
appliances (including extension
cords) in the vicinity of the oxygen supply.
Because 100 percent oxygen can be harmful to
body tissues, doctors administer this level of oxygen
therapy only to treat respiratory crisis. Supplemental
oxygen therapy may be an element of
treatment for cardiovascular conditions such as
ISCHEMIC HEART DISEASE (IHD) and HEART FAILURE as
well as pulmonary conditions such as CHRONIC
OBSTRUCTIVE PULMONARY DISEASE (COPD), PNEUMONIA,
severe ASTHMA, and ATELECTASIS.
In the hospital setting the oxygen supply is centralized,
with access ports in patient care areas.
Oxygen-delivery tubing plugs into the port, with
an individualized flow regulator to adjust the percentage
of oxygen. Oxygen tanks for home oxygen
therapy contain compressed or frozen (liquid)
oxygen, with flow regulators and often a device
that releases oxygen only on inhalation. Home
oxygen therapy may use an oxygen concentrator
instead of supplemental oxygen. An oxygen concentrator
extracts nitrogen from room air to
increase the air’s concentration of oxygen. Oxygen
concentrators can deliver oxygen only at low flow
rates, however, making them useful only for
people who require minimal oxygen supplementation.
It is important to have adequate supplemental
humidification as well during oxygen
therapy, as the higher concentration of oxygen is
drier than environmental air. Oxygen therapy
may be short-term or long-term treatment,
depending on the condition that causes its use.
The person may also use oxygen therapy continuously,
only during sleep, or only during physical
activity depending on his or her underlying disease
and respiratory needs.
Oxygen Therapy Device
nasal cannula
face mask
nonrebreathing mask
transtracheal catheter
endotracheal tube
bag and mask resuscitator
OXYGEN THERAPY
Percentage of Oxygen
25 to 40 percent
30 to 50 percent
50 to 90 percent
up to 100 percent
up to 100 percent
up to 100 percent
See also OXYGEN–CARBON DIOXIDE EXCHANGE; TRA-
CHEOSTOMY.