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U N I T 6
Respiratory Function
upper respiratory tract.
2
The influenza virus can infect
both the upper and lower respiratory tracts. Bacteria
can infect the nose and sinuses, and both bacteria and
fungi can produce infections of the lung, many of which
cause significant morbidity and mortality.
The Common Cold
The common cold is a viral infection of the upper respi-
ratory tract. It occurs more frequently than any other
respiratory tract infection. Most adults have two to
three colds per year, whereas the average school child
may have up to 12 per year.
3
The condition usually
begins with a sore and scratchy throat followed by pro-
fuse and watery rhinorrhea, nasal congestion, sneezing,
and coughing. Other cold symptoms include malaise,
fatigue, headache, hoarseness, sinus congestion, and
myalgia. Fever is a common sign in children but is an
infrequent finding in adults.
3
The disease process is self-
limited, usually lasting up to 10 days.
Initially thought to be caused by either a single “cold
virus” or group, the common cold is now recognized to
be associated with many different viruses.
3,4
The most
common are the rhinoviruses, parainfluenza viruses,
respiratory syncytial virus, coronaviruses, and adenovi-
ruses. Of these, the rhinoviruses are the most common
cause of colds in persons between 5 and 40 years of age.
In children younger than 3 years of age, infections from
the respiratory syncytial virus and parainfluenza viruses
are most common.
The “cold viruses” are rapidly spread from person to
person. Children are the main source of infection often
acquiring a new strain of the virus from another child in
school or day care. The fingers are the greatest source of
spread, and the nasal mucosa and conjunctival surface
of the eyes are the most common portals for entry of the
virus. The most highly contagious period is during the
first 3 days after the onset of symptoms, and the incuba-
tion period is approximately 5 days. Cold viruses have
been found to survive for more than 5 hours on the skin
and hard surfaces, such as plastic countertops.
4,5
Aerosol
spread of colds through coughing and sneezing is much
less important than the spread by fingers picking up the
virus from contaminated surfaces and carrying it to the
nasal membranes and eyes.
5
This suggests that careful
attention to hand washing is one of the most important
preventive measures for avoiding the common cold.
Because the common cold is an acute and self-limited
illness in persons who are otherwise healthy, symptom-
atic treatment with rest and antipyretic drugs is usually
all that is needed. Antibiotics are ineffective against viral
infections and are not recommended.
6
Over-the-counter
(OTC) remedies are available for treating the symptoms of
a common cold. Antihistamines are popular OTC drugs
because of their action indrying nasal secretions. Although
they do not work as a monotherapy, a first-generation
antihistamine in combination with a decongestant may
be slightly beneficial in relieving general symptoms, nasal
congestion, and cough.
6
However, there is no evidence
that they shorten the duration of the cold. They are not
recommended for use in children. Decongestant drugs
(i.e., sympathomimetic agents) are available in OTC
nasal sprays, drops, and oral cold medications. These
drugs constrict the blood vessels in the nasal mucosa and
reduce nasal swelling. Rebound nasal swelling can occur
with indiscriminate or chronic use of nasal drops and
sprays. Oral preparations containing decongestants may
cause systemic vasoconstriction and elevation of blood
pressure when given in doses large enough to relieve
nasal congestion, and they should be avoided in persons
with hypertension, heart disease, hyperthyroidism, dia-
betes mellitus, or other health problems.
3
Rhinosinusitis
The term
rhinitis
refers to an inflammation of the nasal
passages and
sinusitis
to an inflammation of the para-
nasal sinuses.
7–12
Although it has not been universally
accepted, the suggestion has been made that the term
rhinosinusitis
is a more accurate term for what is com-
monly referred to as
sinusitis
, because the mucosa of
the nasal cavities and paranasal sinuses are lined with a
continuous mucous membrane layer and sinusitis rarely
occurs in the absence of infectious or allergic rhinitis.
The paranasal sinuses are air-filled extensions of the
respiratory part of the nasal cavities into the frontal,
ethmoid, sphenoid, and maxilla bones (Fig. 22-1A). The
sinuses, which are named for the bones in which they
are found, are connected by narrow openings or
ostia
with the superior, middle, and inferior nasal turbinates
of the nasal cavity. The anterior ethmoid, frontal, and
maxillary sinuses all drain into the nasal cavity through
a relatively convoluted and narrow passage called the
ostiomeatal complex
(see Fig. 22-1B). The
sphenoidal
sinuses
drain from a separate complex between the sep-
tum and the superior turbinate (see Fig. 22-1C).
The most common causes of rhinosinusitis are con-
ditions that obstruct the narrow ostia that drain the
sinuses. Most commonly, rhinosinusitis develops when
a viral upper respiratory tract infection or allergic rhi-
nitis obstructs the ostiomeatal complex and impairs the
mucociliary clearance mechanism. Nasal polyps also can
obstruct the sinus openings and facilitate sinus infec-
tion. Infections associated with nasal polyps can be
self-perpetuating because constant irritation from the
infection can facilitate polyp growth. Barotrauma caused
by changes in barometric pressure, as occurs in airline
pilots and flight attendants, may lead to impaired sinus
ventilation and clearance of secretions. Swimming, div-
ing, and abuse of nasal decongestants are other causes of
sinus irritation and impaired drainage. Maxillary sinusitis
may result from dental infection, and teeth that are ten-
der should be carefully examined for signs of an abscess.
Clinical Features
Rhinosinusitis can be classified as acute, subacute, or
chronic.
7,8
Acute viral rhinosinusitis may last from 5 to
7 days and acute bacterial rhinosinusitis up to 4 weeks.
Subacute rhinosinusitis lasts from 4 weeks to less than
12 weeks, whereas chronic rhinosinusitis lasts beyond
12 weeks.
