Definition Atelectasis is a condition in which part of the lung becomes airless and contracts.
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 little air cavities called alveoli, which looks 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. With each normal breath, 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. Atelectasis prevents the lung from being able to pass oxygen to the blood.
What are the signs and symptoms of the condition? Symptoms depend on how much of the lung is involved. A person may not even be aware of atelectasis if only a small part of the lung is affected. But, if a large part of the lung is involved, a person may have these symptoms:
What are the causes and risks of the condition? There are several different 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 normal 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 complication of anaesthesia after surgery.
Compressive atelectasis results when the air passages are closed from the outside. An enlarging lung tumour 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. This can be caused by congenital disorders such as hyaline membrane disease. Without surfactant, the alveolar walls alone cannot keep the alveoli open.
What can be done to prevent the condition? A person can reduce his or her risk for this condition by exercising regularly and by not smoking or breathing in second-hand smoke.
Atelectasis can also be a complication of surgery. When possible, doctors should:
have the person breathe on his or her own after surgery, rather than relying on a ventilator, or artificial breathing machine
minimise the time a person spends under anaesthesia
help the person breathe deeply, cough, and walk around right after surgery
use incentive spirometers, or inexpensive plastic meters, to increase airflow into the lungs after the surgery
How is the condition diagnosed? Atelectasis is diagnosed by a person's symptoms and the physical examination findings. A chest x-ray that shows the airless part of the lung confirms the diagnosis. A chest CT scan may be done to find the cause.
What are the long-term effects of the condition? The long-term effects are often related to the cause. Atelectasis due to surgery should have no long-term effects. Once treated with breathing exercises, the lung should function normally again. Chronic illnesses, such as emphysema or cystic fibrosis, may result in atelectasis that never completely resolves. Scar tissue can form inside of the lung as a result of chronic atelectsis. These scarred areas never function properly.
What are the risks to others? People with congenital lung diseases, such as cystic fibrosis, may pass a risk of atelectasis on to their children.
What are the treatments for the condition? Medications are often used, depending on the problem. For instance, medications can:
thin respiratory secretions during illnesses such as pneumonia
open the bronchial tubes
stimulate surfactant production
Controlling the pain in people with chest traumas or people who have undergone surgery is very important. This enables them to do deep breathing exercises, forcing air into their lungs. These exercises open the alveoli and reduces atelectasis.
Some people receive relief from chest physiotherapy. This can mechanically remove mucous blocking the airways. Sometimes suctioning the airway with a small plastic tube can be helpful.
What are the side effects of the treatments? The side effects of treatment are much less distressing than the atelectasis. Each medication will have side effects. Suctioning can be very hard to tolerate, but usually relieves the blockage quite well.
What happens after treatment for the condition? After treatment, if the cause was short-term as in surgery, the lungs will usually recover fully. But, if the cause was cystic fibrosis or emphysema, the illness may persist and symptoms will recur.
How is the condition monitored? Monitoring is done with regular physical examinations and routine chest x-rays. Respiratory function tests are performed as needed. These are tests that measure the lungs capacity to hold air. They also measure the lungs ability to move air in and out, and to exchange oxygen and carbon dioxide.
Author: Vincent J. Toups, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 25/04/2005 Contributors Potential conflict of interest information for reviewers available on request
