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Atelectasis

Symptoms, Diagnosis, and Treatment

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Updated April 11, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

If your doctor says you have atelectasis, you may be confused and frightened. What does this mean, what are the causes, and what do you need to know?

What is the Definition of Atelectasis?

Atelectasis is defined as the collapse of part or all of the lungs. When this occurs, for whatever reason, fresh air does not reach the tiniest of airways called the alveoli, and oxygen and carbon dioxide can’t be exchanged. This, in turn, can lead to decreased levels of oxygen being delivered to the organs and tissues of the body (hypoxia).

Atelectasis may be acute, occurring suddenly over a matter of minutes, or chronic, developing over a period of days to weeks.

Symptoms

Atelectasis may have few or no symptoms if it develops slowly or involves only a small portion of the lungs. Conversely, if the condition affects a large portion of the lungs, or develops rapidly, symptoms may be dramatic and may even progress to shock. Common symptoms include:
  • Shortness of breath – A sensation of breathlessness is the most common symptom.

  • Coughing – This cough is often described as “hacking” and is most often non-productive, meaning that no mucous is coughed up.

  • Pleurisy – Chest pain that is sharp and worsens with a deep breath or coughing (pleuritic chest pain) may occur.

  • Fever – At one time, it was thought that fever was a sign—but this no longer appears to be the case. However, a fever may occur if complications, such as pneumonia, occur.

  • Cyanosis – When enough alveoli are blocked, oxygen is unable to reach the blood, resulting in hypoxemia: a diminished level of oxygen in the blood. This can cause the skin—especially the fingers, toes, and lips—to develop a bluish coloration (cyanosis).

  • Signs of shock – Symptoms such as low blood pressure and a rapid heart rate may be present if the condition occurs suddenly, or involves a large portion of the lungs.

Causes

There are 4 primary mechanisms that can cause atelectasis. These include:
  • 1. Obstruction - Blockage of an airway, either from inside (for example, by a foreign body that is aspirated, or a mucous plug), or the outside (for example, by a lung cancer pressing on the airway), can result in collapse of a portion of the lung. With one type of lung cancer, broncioloalveolar carcinoma (BAC), the smallest airways (alveoli) are filled with tumors.

  • 2. Compression - Compression of the airways in the lungs can be caused by fluid or air surrounding the lungs (as in a pleural effusion or a pneumothorax); by enlargement or an aneurysm of the heart; by tumors such as cancers metastatic to the lungs, lymphomas, or enlarged lymph nodes; or by abdominal distention which causes pressure on the lungs.

  • 3. Adhesion - The alveoli are held open by a substance called surfactant. When this substance is lacking, the lungs lose surface tension and can collapse. This is perhaps best understood as the cause of respiratory distress in newborns. Loss of surfactant can also occur in adults with adult respiratory distress syndrome (ARDS), smoke inhalation, and kidney failure.

  • 4. Hypoventilation - Failure to take deep breaths can result in collapse of part of the lungs. This is very common during surgery, especially with general anesthesia, and when breathing is shallow due to pain (such as with rib fractures). Hypoventilation is the most common cause of atelectasis.

Risk Factors

Factors that raise your risk of developing atelectasis include anything that can predispose you to obstruction of your airways, that cause compression to your lungs, or that cause you to breathe less deeply than usual. Risk factors may include:
  • Surgery - Surgery, especially surgery involving your chest or upper abdomen, is a common cause of atelectasis.
  • General Anesthesia
  • Lung conditions – Conditions such as COPD and cystic fibrosis can produce mucous plugs, which contribute to collapse of part of the lungs.
  • Pleural effusions – Both benign and malignant pleural effusions may compress the airways.
  • Tumors – Including lung cancer, lymphomas, and metastatic cancer to the lungs from other regions of the body.
  • Rib fractures and other chest injuries – Any injury that results in shallow breathing can be a risk factor.
  • Immobility/prolonged bedrest
  • Inhalation of a foreign object – Such as choking on peanuts.
  • Deficiency of surfactant - Such as with respiratory distress syndrome (RDS) and ARDS.
  • Smoking
  • Age
  • Asbestos exposure – Due to scarring and contraction of the lining of the lungs (the pleura).
  • High G’s – Fighter pilots are at risk of atelectasis.
  • Narcotics and sedatives – Large doses of sedative medications can cause shallow breathing.
  • Chest deformities that limit respiration
  • Neurological disorders - Disorders that interfere with respiration such as myasthenia gravis, amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS).
  • Tight bandages – Bandages (such as rib belts) that restrict respiration can lead to the condition. This is one of the reasons that rib belts are used less often than they were in the past for rib fractures.
  • Obesity – Especially abdominal obesity due to pressure exerted upwards on the lungs.

Diagnosis

If your doctor suspects you have atelectasis based on your symptoms or risk factors, further tests may include a:
  • Physical exam – Findings that suggest atelectasis may include quiet or absent breath sounds. Your doctor may also tap on your chest – something called percussion – to listen for sounds that are common when atelectasis is present.

  • Chest x-ray – Atelectasis is a very common finding on a chest x-ray. On a chest x-ray, the trachea and heart may be deviated towards the side of the chest where a lung is partially collapsed. The diaphragm may also be elevated on the side of the collapse.

  • Chest CT scan – A chest CT scan may further define an area of possible atelectasis. It may also be done to look for other causes of obstruction, such as tumors or enlarged lymph nodes.

  • BronchoscopyBronchoscopy, a test in which a fiberoptic scope is placed through the mouth and down into the bronchi, may be used to determine the cause of a bronchial obstruction. It may also be used to treat the condition by removing mucous plugs or a foreign body.

  • Blood gases – Blood gases or oximetry may be done to determine how much atelectasis is interfering with the ability to get oxygen to your tissues.

Other tests may be ordered depending upon the condition; for example, a PET scan for cancer, an MRI, or bloodwork to evaluate kidney function.

Treatment

Treatment of atelectasis will depend upon the underlying cause, with the goal being to re-expand the collapsed portion of the lung. For example, if a tumor is pressing on the airways causing collapse, treatment of the tumor with surgery, chemotherapy, or radiation may be recommended. Treatment usually consists of a combination of therapies rather than a single treatment.

If airway obstruction is caused by a foreign body, mucous plug, or tumor, bronchoscopy may be used to remove the blockage and correct the obstruction. Postural drainage and chest percussion (chest physiotherapy) may also be helpful. If the lungs are compressed by a pleural effusion, draining the effusion may be recommended.

An incentive spirometer may be used to encourage deep breathing. Lying on the side of your healthy lung may help to expand the blocked lung. Bronchodilators, medications that help expand the airways, may be given by nebulizer.

When symptoms are pronounced, positive end-expiratory pressure (PEEP) may be used. This is a treatment in which a mixture of oxygen is given by mask under pressure, preventing the lungs from collapsing completely during expiration. Steroids may be used to decrease inflammation, and antibiotics are given if signs of an infection are present. If symptoms are severe, intubation and ventilation may be needed until the underlying condition is under control.

When atelectasis is chronic, it can be difficult to get the lungs to re-expand. Removal of the involved part of the lung via a lobectomy or segmental resection may then be needed.

Prevention

Ideally, atelectasis can be prevented in the first place, though this is not always possible. The use of incentive spirometry, frequent position changes, and getting up and moving around as soon as possible after surgery are all helpful. If you smoke, quitting for a month or two before surgery lowers the risk. Cough medications should be avoided in those at risk, as they suppress the cough reflex.

Complications

Complications may result when bacteria become trapped in the area of collapse leading to infection (pneumonia and sepsis). Bronchiectasis, an abnormal widening of the airways that results in fluid pooling in the lungs, may occur, especially when symptoms occur in childhood. When a large portion of the lungs are affected, respiratory failure may result.

Prognosis

Prognosis will depend largely upon the underlying cause, and how much of the lungs are involved. When only a small area of the lungs are affected, or the collapse is mild (such as after many surgeries), prognosis is often excellent. On the other hand, atelectasis can be a life threatening condition when a larger portion of the airways are involved, or the symptoms occur rapidly.

Questions to Ask Your Doctor:

  • What caused a part of my lungs to collapse?
  • What can I expect? How long will it last?
  • What treatments do you recommend? If these fail, what is the next step?
  • What can I do for myself (such as deep breathing), to improve my symptoms?
  • What complications should I watch for? When should I call?

Describing Atlectasis

If your doctor talks about atelectasis, or you look at your chest x-ray report, there are many terms that are used to describe the condition. While it can be frightening to see these terms, they basically describe one of two things. They may describe the location of the collapse; for example, lobar atelectasis refers to collapse of part or all of a lobe of the lungs due to an obstruction in a lobar bronchus—that is, the airway going to the lobe. Basilar atelectasis refers to collapse near the base of one or both lungs. Terms are also used to describe what the area of collapse looks like on imaging tests. For example, “plate-like,” “discoid,” or “linear.”

Sources:

Mavros, M., Velmahos, G., and M. Falagas. Atelectasis as a Cause of Postoperative Fever. Where is the clinical evidence?. Chest. 2011. 140(2):418-24.

McCool, F., and M. Rosen. Nonpharmacologic Airway Clearance Therapies: ACCP Evidence-Based Clinical Practice Guidelines. Chest. 2006. 129(1 Suppl):250S-259S.

National Institute of Health. MedlinePlus. Atelectasis. Updated 09/15/10. http://www.nlm.nih.gov/medlineplus/ency/article/000065.htm

Schindler, M. Treatment of Atelectasis – where is the evidence?. Critical Care. 2005. 9(4):341-2.

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