CHAPTER 2 Respiratory System^107
Emphysema
WHAT WENT WRONG?
Chronic inflammation reduces the flexibility of the walls of alveoli, resulting in
over-distention of the alveolar walls. This causes air to be trapped in the lungs,
impeding gas exchange. Smoking is often linked to development of emphysema.
A less frequent cause is an inherited alpha 1 -antitrypsan deficiency.
PROGNOSIS
Symptoms often begin insidiously and are progressive. Shortness of breath is ini-
tially associated with exertion, then presents at rest. These patients are more sus-
ceptible to lung infections. Supplemental oxygen becomes necessary at first for
exacerbations, then for daily use. Periodic exacerbations requiring hospitalization
are not unusual.
HALLMARK SIGNS AND SYMPTOMS
- Difficulty breathing (dyspnea) due to air trapping, which retains carbon
dioxide and reduces alveolar gas exchange. - Barrel chest develops over time as more air is trapped within the distal air-
ways. The anteroposterior diameter (distance between front and back of the
chest) increases, giving the chest a more barrel-like appearance. - Use of accessory muscles to breathe as the respiratory effort increases. The
number of muscles used to inhale will increase in an effort to get enough
oxygen into the body. - Loss of weight as extra calories are needed to maintain respiration. Increased
effort of breathing also detracts from eating. - Patients prefer a seated position which allows for greater chest expansion.
INTERPRETING TEST RESULTS
- Increased residual volume shown in pulmonary function test due to air
trapping.
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