as relatively reduced CT attenuation at subpleural or peribronchovascular areas with or without intact interlobular septa
Paraseptal emphysema is a
- chronic lung condition
- characterized by the destruction and enlargement of the alveoli
- involves the peripheral areas of the lungs,
- Alveolar Destruction:
- the walls of the alveoli in the peripheral areas of the lungs
- become damaged and
- lose their elasticity.
- Air Trapping:
- As the alveoli lose their elasticity, t
- become less efficient at expelling air during exhalation.
- leads to air becoming trapped in these distal alveolar spaces, resulting in localized overinflation.
- Tension of the pleura
- pulling on the periphery of the lung during inspiration
- contributes to greater mechanical stress on the peripheral alveoli.
- Stress Distribution:
- The tension on the pleura is
- transmitted to the adjacent alveoli.
- Stretching and Shearing
- The mechanical forces
- can cause stretching and shearing forces on the alveoli.
- result in damage to the alveolar walls and
- more so if smoking or disease
- have caused decreased elasticity
- Stress Distribution:
-
- Bullae Formation:
- Prolonged air trapping and
- overinflation can cause the
- formation of large, bullae.
- can exert pressure on surrounding lung tissue and interfere with normal lung function.
- Associated Conditions:
- often associated with other forms of emphysema,
- Smoking is a significant risk factor
- as well as other lung conditions.
- Why does paraseptal emphysema affect the periphery of the lungs?
- due to differences in ventilation and anatomical structure within the lung tissue.
- Ventilation Distribution:
- The lungs are not uniformly ventilated throughout their structure.
- Peripheral lung regions, which are further away from the main airways,
- receive less ventilation compared to the central regions.
- Alveolar Structure: The alveoli, in the peripheral or subpleural areas
- have thinner walls
- Pressure Differences:
- alveoli near the periphery have
- relatively higher pressures during exhalation
- due to the increased resistance
- lead to stress and strain on the alveolar walls
- alveoli near the periphery have
- Air Trapping:
- When air becomes trapped in the alveoli due to reduced elasticity of the alveolar walls,
- tends to accumulate more in the peripheral regions