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Atelectasis is a collapse of lung tissue affecting part or all of one lung. This condition prevents normal oxygen absoption to healthy tissues.


Atelectasis can result from an obstruction (blockage) of the airways that affects tiny air scas called alveoli. Alveoli are very thin-walled and contain a rich blood supply. They are important for lung function, since their purpose is the exchange of oxygen and carbon dioxide. When the airways are blocked by a mucous "plug," foreign object, or tumor, the alveoli are unable to fill with air and collapse of lung tissue can occur in the affected area. Atelectasis is a potential complication following surgery, especially in individuals who have undergone chest or abdominal operations resulting in associated abdominal or chest pain during breathing. Congenital atelectasis can result from a failure of the lungs to expand at birth. This congenital condition may be localized or may affect all of both lungs.

Causes and symptoms

Causes of atelectasis include insufficient attemps at respiration by the newborn, bronchial obstruction, or absence of surfactant (a substance secreted by alveoli that maintains the stability of lung tissue by reducing the surface tension of fluids that coat the lung). This lack of surfactant reduces the surface area available for effective gas exchange causing it to collapse if severe. Pressure on the lung from fluid or air can cause atelectasis as well as obstruction of lung air passages by thick mucus resulting from various infections and lung diseases. Tumors and inhaled objects can also cause obstruction of the airway, leading to atelectasis.
Anyone undergoing chest or abdominal surgery using general anesthesia is at risk to develop atelectasis, since breathing is often shallow after surgery to avoid pain from the surgical incision. Any significant decrease in airflow to the alveoli contributes to pooling of secretions, which in turn can cause infection. Chest injuries causing shallow breathing, including fractured ribs, can cause atelectasis. Common symptoms of atelectasis include shortness of breath and decreased chest wall expansion. If atelectasis only afects a small area of the lung, symptoms are ususally minimal. If the condition affects a large area of the lung and develops quickly, the individual may turn blue (cyanotic) or pale, have extreme shortness of breath, and feel a stabbing pain on the affected side. Fever and increased heart rate may be present if infection accompanies atelectasis.


To diagnose atelectasis, a doctor starts by recording the patient's symptoms and performing a thorough physical examination. When the doctor listens to the lungs through a stethoscope (ausculation), diminished or bronchial breath sounds may be heard. By tapping on the chest (percussion) while listening through the stethoscope, the doctor can often tell if the lung is collapsed. A chest x ray that shows an airless area in the lung confirms the diagnosis of atelectasis. If an obstruction of the airways is suspected, a computed tomography scan (CT) or bronchoscopy may be performed to locate the cause of the blockage.


If atelectasis is due to obstruction of the airway, the first step in treatment is to remove the cause of the blockage. This may be done by coughing, suctioning, or bronchoscopy. If a tumor is the cause of atelectasis, surgery may be necessary to remove it. Antibiotics are commonly used to fight the infection that often accompanies atelectasis. In cases where recurrent or long-lasting infection is disabling or where significant bleeding occurs, the affected section of the lung may be surgically removed.

Key terms

Alveoli — Tiny air sacs in the lungs where gas exchange takes place between alveolar air and pulmonary blood within the capillaries
Bronchial — Relating to the air passages to and from the lungs including the bronchi and the bronchioles.
Bronchoscopy — A procedure in which a hollow, flexible tube is inserted into the airway to allow visual examination of the larynx, trachea, bronchi, and bronchioles. It is also used to collect specimens for biopsy or culturing and to remove airway obstructions.
Incentive spirometer — A breathing device that provides feedback on performance to encourage deep breathing.
Mucus — A thin, slippery film secreted by the mucous membranes and glands.
Postural drainage — Techniques to help expel excess mucus by specific poistions of the body (that decrease the effects of gravity) combined with manual percussion and vibration over various parts of the lung.
Surfactant — A substance secreted by the alveoli in the lungs that reduces the surface tension of lung fluids, allowing gas exchange and helping maintain the elasticity of lung tissue.
Tumor — An abnormal growth of tissue resulting from uncontrolled, progressive multiplication of cells.


If atelectasis is caused by a thick mucus "plug" or inhaled foreign object, the patient usually recovers completely when the blockage is removed. If it is caused by a tumor, the outcome depends on the nature of the tumor involved. If atelectasis is a result of surgery, other postoperative conditions and/or complications affect the prognosis.


When recovering from surgery, frequent repositioning in bed along with coughing and deep breathing are important. Coughing and breathing deeply every one to two hours after any surgical operation with general anesthesia is recommended. Breathing exercises and the use of breathing devices, such as an incentive spirometer, may also help prevent atelectasis. Although smokers have a higher risk of developing atelectasis following surgery, stopping smoking six to eight weeks before surgery can help reduce the risk. Increasing fluid intake during respiratory illness or after surgery (by mouth or intravenously) helps lung secretions to remain loose. Increasing humidity may also be beneficial.
Postural drainage techniques can be learned from a respiratory therapist or physical therapist and are a useful tool for anyone affected with a respiratiory illness that could cause atelectasis. Because foreign objects blocking the airway can cause atelectasis, it is very important to keep small objects that might be inhaled away from young children.



National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a collapsed or airless state of the lung, which may be acute or chronic, and may involve all or part of the lung. The primary cause is obstruction of the bronchus serving the affected area. adj., adj atelectat´ic. ƒ

In congenital atelectasis of the fetus or newborn, the lungs fail to expand normally at birth. This may be due to any of a variety of causes, including prematurity (often accompanying hyaline membrane disease); diminished nervous stimulus to breathing and crying; fetal hypoxia from any cause, including oversedation of the mother during labor and delivery; or obstruction of the bronchus by a mucous plug.

In older individuals atelectasis may be the result of airway obstruction, as by secretions or a tumor (called obstructive, absorption, or acquired atelectasis); or it may be from a failure to deep breathe, such as postoperatively or because of neuromuscular disease. It occurs most commonly as a complication in the postoperative period, when deep breathing and incentive spirometry are often used to prevent or treat it.
 Mechanisms of atelectasis. A, Collapse of the lung in pneumothorax. B, Compression of the lung by pleural fluid. C, Resorption of the air from alveoli distal to an obstructed bronchus. Obstructive atelectasis is usually focal. Atelectasis of premature infants, which is caused by a deficiency of pulmonary surfactant, is not shown. From Damjanov, 2000.
Symptoms. In acute atelectasis in which there is sudden obstruction of the bronchus, there may be dyspnea and cyanosis, elevation of temperature, a drop in blood pressure, or shock. In the chronic form, the patient may experience no symptoms other than gradually developing dyspnea and weakness.

X-ray examination may show a shadow in the area of collapse. If an entire lobe is collapsed, the x-ray will show the trachea, heart, and mediastinum deviated toward the collapsed area, with the diaphragm elevated on that side.
Treatment. Atelectasis in the newborn is treated by suctioning the trachea to establish an open airway, positive-pressure breathing, and administration of oxygen. High concentrations of oxygen given over a prolonged period tend to promote atelectasis and may lead to the development of retrolental fibroplasia in premature infants.

Acute atelectasis is treated by removing the cause whenever possible. To accomplish this, coughing, suctioning, and bronchoscopy may be employed. In atelectasis due to airway obstruction with secretions, chest physiotherapy is often useful. Chronic atelectasis usually requires surgical removal of the affected segment or lobe of lung. Antibiotics are given to combat the infection that almost always accompanies secondary atelectasis.
absorption atelectasis (acquired atelectasis) that produced by any factor, e.g., secretions, foreign body, tumor, or abnormal external pressure, that completely obstructs the airway, preventing intake of air into the alveolar sacs and permitting absorption of air into the bloodstream. Called also obstructive or secondary atelectasis.
congenital atelectasis that present at birth (primary atelectasis) or immediately after (secondary atelectasis).
lobar atelectasis that affecting only a lobe of the lung; called also segmental atelectasis.
lobular atelectasis that affecting only a lobule of the lung.
obstructive atelectasis absorption atelectasis.
passive atelectasis relaxation atelectasis.
primary atelectasis congenital atelectasis in which the alveoli have never been expanded with air.
relaxation atelectasis atelectasis because of large amounts of air or fluid in the pleural cavity, as in pneumothorax or pleural effusion. Called also passive atelectasis.
round atelectasis (rounded atelectasis) a localized, reversible form in subjacent peripheral tissue, often following pleural effusion and characterized by focal pleural scarring.
secondary atelectasis
congenital atelectasis in which resorption of the contained air has led to collapse of the alveoli.
segmental atelectasis lobar atelectasis.
subsegmental atelectasis that affecting only the part of a lung distal to an occluded segmental bronchus.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Decrease or loss of air in all or part of the lung, with resulting loss of lung volume itself.
See also: pulmonary collapse.
[G. atelēs, incomplete, + ektasis, extension]
Farlex Partner Medical Dictionary © Farlex 2012


n. pl. atelecta·ses (-sēz′)
1. The absence of gas from all or part of the lung, due to failure of expansion of the alveoli.
2. A congenital condition characterized by incomplete expansion of the lungs.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


The partial or total collapse of lung parenchyma, due to obstruction of a bronchus by a mucus plug, infection or cancer; it commonly occurs following general anaesthesia.

Clinical findings
Low-grade fever, dry cough, chest pain, shortness of breath.

Mild atelectasis is treated with deep breathing exercises and respiratory therapy; atelectasis secondary to cancer may be managed by therapeutic bronchoscopy.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Partial lung collapse Chest medicine The partial or total collapse of lung parenchyma, due to obstruction of a bronchus by a mucus plug, infection or CA; it is common post general anesthesia Clinical Low-grade fever, dry cough, chest pain, SOB Management Mild atelectasis is treated with deep breathing exercises and respiratory therapy; atelectasis 2º to CA may be managed by therapeutic bronchoscopy. See Plate atelectasis.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


Reduction or absence of air in part or all of a lung, with resulting loss of lung volume.
See also: pulmonary collapse
[G. atelēs, incomplete, + ektasis, extension]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Failure of the normal expansion of part or all of a lung. This is a feature of the RESPIRATORY DISTRESS SYNDROME of premature babies. The term may be used more generally to refer to failure of dilatation of a part that normally dilates.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


Decrease or loss of air in all or part of the lung, with resulting loss of lung volume itself.
[G. atelēs, incomplete, + ektasis, extension]
Medical Dictionary for the Dental Professions © Farlex 2012