- • The most common symptoms of pneumothorax are
chest pain and dyspnea.
- • Physical signs include hyperresonant percussion,
diminished tactile and vocal fremitus, and decreased or absent breath
- • Laboratory abnormalities include hypoxia and a
widened P(a–a)O2 gradient.
Pco2 may be either decreased
- • Radiographic signs include the peripheral absence
of lung markings and the presence of a pleural “stripe” that
is strictly intrathoracic.
Pneumothorax, defined as the presence of air within the pleural
space, is classified as either spontaneous or traumatic. Spontaneous
pneumothorax occurs without obvious cause and is subclassified as
either primary or secondary. Primary spontaneous pneumothorax occurs
in the absence of underlying lung disease. Secondary spontaneous
pneumothorax occurs as a complication of underlying lung disease.
The incidence of primary and secondary pneumothorax is similar,
with both conditions being more common in males than females. The
incidence of primary spontaneous pneumothorax in a longitudinal
health study in Olmsted County, Minnesota was 7.4/100,000/year
in males and 1.2/100,000/year in females. It is
more common in younger persons, with a peak incidence in the third
decade of life, and is rare after age 40. The incidence of secondary spontaneous
pneumothorax in the Olmsted County, Minnesota study was 6.3/100,000/year
in males and 2.0/100,000/year in females. Secondary
spontaneous pneumothorax is more commonly associated with severe
respiratory compromise due to lack of significant respiratory reserve
from the underlying lung disease.
Traumatic pneumothorax, which results from direct or indirect
trauma to the chest, is subclassified as either iatrogenic or noniatrogenic.
Iatrogenic pneumothorax is the most common type of pneumothorax.
Tension pneumothorax occurs when intrapleural pressure exceeds
atmospheric pressure throughout expiration. Although any pneumothorax
can cause this, the most common cause of tension pneumothorax is
barotrauma from positive pressure mechanical ventilation. Tension
pneumothorax is a medical emergency that is frequently associated
with hemodynamic instability and considerable mortality.
Barton ED: Tension pneumothorax. Curr Opin Pulmon
of the clinical manifestations and pathophysiology of tension pneumothorax.)
Primary spontaneous pneumothorax results from rupture of subpleural
emphysematous blebs. The blebs tend to occur more commonly in lung
apices. Although the etiology of the blebs is unknown, epidemiological
observations that identify risk factors for primary spontaneous
pneumothorax offer clues to processes that may contribute to their
development. These studies indicate that tobacco use, body habitus,
and family history are risk factors for this condition. For example, primary
spontaneous pneumothorax is more common in tall, thin males. There
is also a familial tendency to this type of pneumothorax; up to
11% of patients with primary spontaneous pneumothorax have
a family history of spontaneous pneumothorax. Patients with primary
spontaneous pneumothorax are also more likely to have bronchial
abnormalities such as narrowed airways and missing or ...