C h a p t e r 2 3
Disorders of Ventilation and Gas Exchange
583
fourth generation of bronchi (see Chapter 21, Fig. 21-4).
These bronchi become severely dilated and end blindly
in dilated sacs, with collapse and fibrosis of more distal
lung tissue. Cylindrical bronchiectasis involves uniform
and moderate dilation of the sixth to eighth genera-
tions of airways. It is a milder form of disease than
saccular bronchiectasis and leads to fewer symptoms.
Varicose bronchiectasis involves the second through
eighth branchings of bronchi and results in bronchi that
resemble varicose veins. Bronchiolar obliteration is not
as severe and symptoms are variable.
Bronchiectasis can present in either of two forms:
a local obstructive process involving a lobe or segment
of a lung or a diffuse process involving much of both
lungs.
16
Localized bronchiectasis
is most commonly
caused by conditions such as tumors, foreign bodies,
and mucus plugs that produce atelectasis and infection
due to obstructed drainage of bronchial secretions. It
can affect any area of the lung, the area being deter-
mined by the site of obstruction or infection.
Generalized
bronchiectasis
usually is bilateral and most commonly
affects the lower lobes. It is due largely to inherited
impairments of host mechanisms or acquired disor-
ders that permit introduction of infectious organisms
into the airways. They include cystic fibrosis, in which
airway obstruction is caused by impairment of normal
mucociliary function; congenital and acquired immu-
nodeficiency states, which predispose to respiratory
tract infections; lung infection (e.g., tuberculosis, fungal
infections, lung abscess); and exposure to toxic gases
that cause airway obstruction.
Manifestations
Bronchiectasis is usually manifested by a chronic produc-
tive cough, often with several hundred milliliters of foul-
smelling, purulent sputuma day.
16
Hemoptysis is common.
Dyspnea and wheezing occur in about 75% of patients.
6
Weight loss, anemia, and other systemic manifestations
are common.
10
Clubbing of the fingers is infrequent in
mild cases, but common in severe disease. Obstructive
pulmonary dysfunction with hypoxemia is seen in moder-
ate to severe cases. However, due to improved treatment
with better antibiotics and physical therapy, outcome and
life expectancy have improved considerably.
Diagnosis andTreatment
Diagnosis is based on history and imaging studies. The
condition often is evident on chest radiographs. High-
resolution CT scanning of the chest allows for definitive
diagnosis. Accuracy of diagnosis is important because
interventional bronchoscopy or surgery may be pallia-
tive or curative in some types of obstructive disease.
Treatment consists of early recognition and manage-
ment of infections along with regular postural drainage
and chest physical therapy. Persons with this disorder
benefit from many of the rehabilitation and treatment
measures used for chronic bronchitis and emphysema.
Cystic Fibrosis
Cystic fibrosis (CF), which is a major cause of severe
chronic respiratory disease in children and young
adults, is an inherited disorder involving fluid secre-
tion by the exocrine glands in the epithelial lining of the
respiratory, gastrointestinal, and reproductive tracts.
48–51
In addition to chronic respiratory disease, CF is mani-
fested by pancreatic exocrine deficiency and elevation of
sodium chloride in the sweat. Nasal polyps, sinus infec-
tions, pancreatitis, and cholelithiasis also are common.
Excessive loss of sodium in the sweat predisposes young
children to salt depletion episodes. Most males with CF
have congenital bilateral absence of the vas deferens
with azoospermia.
Cystic fibrosis is inherited as an autosomal recessive
trait. Homozygotes have all or substantially all of the
clinical symptoms of the disease, compared with het-
erozygotes, who are carriers of the disease but have no
recognizable symptoms. Cystic fibrosis occurs most fre-
quently in white populations of northern Europe, North
America, and Australia/New Zealand.
51
Although it
occurs less frequently among African, Hispanic, Middle
Eastern, South Asian, and Eastern Asian populations, it
may occur in these populations as well.
FIGURE 23-11.
Bronchiectasis.The resected upper lobe shows
widely dilated bronchi, with thickening of the bronchial walls
and collapse and fibrosis of the pulmonary parenchyma. (From
Bearsley MB,TravisWD, Rubin E.The respiratory system. In:
Rubin R, Strayer DS, eds. Rubin’s Pathology: Clinicopathologic
Foundations of Medicine. 6th ed. Philadelphia, PA: Wolters
Kluwer Health | Lippincott Williams &Wilkins; 2012:545.)
