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, in turn, is composed of thousands of small air cavities called alveoli, which look somewhat like a honeycomb. Each alveolus 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 and 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.
An individual is at increased risk for atelectasis if he or she:
has a congenital lung disease, such as cystic fibrosis
has a neuromuscular disease, such as amyotrophic lateral sclerosis or multiple sclerosis
has chest trauma, such as a crush injury
- has emphysema
What can be done to prevent the condition?
In some cases, a person may be able to 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, healthcare professionals should:
have the person breathe on his or her own after surgery, rather than relying on a ventilator (artificial breathing machine)
limit the time a person spends under anesthesia
help the person breathe deeply, cough, and walk around immediately after surgery
- use incentive spirometers, which are inexpensive plastic meters, to encourage the individual to breathe more deeply after the surgery
How is the condition diagnosed?
Atelectasis is diagnosed by a person's symptoms and the physical exam findings. A chest x-ray that shows the airless part of the lung confirms the diagnosis. A chest CT scan may help the doctor find the cause.
Long Term Effects
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 well 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 atelectasis. These scarred areas may never function well again.
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?
Medicines are often used, depending on the problem. For instance, medicines 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 reduce atelectasis.
Some people receive relief from chest physical therapy. This is done by clapping or patting the chest and back with one's hands, or rattling it with a vibrating machine. The purpose is to dislodge mucus from the lungs so it can be coughed up more easily. Sometimes suctioning the airway with a small plastic tube may help.
What are the side effects of the treatments?
The side effects of treatment are much less distressing than the atelectasis. Each medicine will have side effects. Suctioning can be 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 exams and routine chest x-rays. Pulmonary function tests are done as needed. These tests measure how much air the lungs can hold. They also measure how well the lungs move air in and out, and how well they exchange oxygen and carbon dioxide.
Conn's Current Therapy. Rakel, 1999
Physiological Basis of Medical Practice. Best and Taylor's. 1985