Atelectasis
Alternate Names : Airless Lung
Atelectasis is a condition in which part of the lung becomes
airless and collapses.
What is going on in the body?
The lungs are divided into large sections called lobes.
Each lobe is divided into smaller segments. Each of these segments
is composed of thousands of small air cavities. These tiny spaces
are called alveoli, and they look somewhat like a honeycomb. Each
alveoli is held open by complex
walls called alveolar walls. These walls, along with a substance called
surfactant that is produced by the lung, help keep the alveoli open and
filled with air. When healthy people breathe, air travels all the way down the
bronchial tubes to the alveoli. It is through these walls that gases like
oxygen are transferred into the blood. When the alveoli cannot stay
open, atelectasis occurs. When that happens, the lung cannot
pass oxygen to the blood.
What are the causes and risks of the condition?
There are several types of atelectasis.
Obstructive atelectasis occurs when something prevents
air from reaching the alveoli. This blockage may be caused by:
something stuck in the airway, such as a peanut or sunflower seed
diseases such as pneumonia,
where mucous becomes thick
myasthenia gravis,
an autoimmune disorder leading to episodes of muscle weakness
hypoventilation, a condition that occurs when there is a decrease in the
usual amount of air that enters the lungs when a person breathes in. This
can be caused by shallow breathing, which is often the result of
chest pain.
Decreased airflow to the lungs also can be a side effect of
anesthesia
after surgery.
Compressive atelectasis results when the air passages are
closed from the outside. An enlarging lung tumor may press on the
outside of the larger bronchial tubes, resulting in partial or complete closure.
Adhesive or congenital atelectasis results from the lack of
surfactant. Surfactant is a protein found naturally in the lungs that helps with
gas exchange in the alveoli. It also helps keep the lungs elastic. This type of
atelectasis can be caused by congenital disorders such as hyaline
membrane disease. Without surfactant, the alveolar walls alone cannot
keep the alveoli open.
People are more at risk for atelectasis if they:
are obese
have a congenital lung disease, such as cystic fibrosis
have a neuromuscular disease, such as amyotrophic lateral sclerosis or multiple sclerosis
have chest trauma, such as a crush injury
have emphysema
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