Obstructive Atelectasis

by Shaun Damon

Atelectasis refers to a partial or complete collapse of the lungs. The different types of atelectasis can be classified as obstructive atelectasis and non-obstructive atelectasis depending on the underlying cause.

Obstructive atelectasis is caused by the blockage of the bronchial passages, usually by a foreign body. It causes air to get trapped in the alveoli which is then slowly absorbed by the blood. It may occur as a consequence of anesthesia. This happens because the mucus secretions of the lungs usually increase under the effect of the anesthesia, causing the excess mucus to be pushed out of the bronchi by coughing. The excess mucus may form a mucus plug that blocks the airways. Other causes of blockages that may result in obstructive atelectasis include:

  • Mucus plugs may be formed during severe bouts of asthma or in persons suffering from cystic fibrosis. Certain drugs such as those administered during surgery may prevent the lungs from inflating completely, leading to a collection of mucus secretions that form mucus plugs.
  • Inhaling a foreign body may also cause a blockage of the bronchial airways. This is most commonly seen in the case of children who may inadvertently inhale some food such as a nut or a small toy.
  • Tumors in a major airway may also cause a blockage of the airway.
  • Blood clots may also block the bronchial airways. This usually results when there is bleeding taking place into the lungs that cannot be coughed up.
On many occasions, there are no apparent symptoms of atelectasis. However, symptoms when they are present may include:

  • Rapid and shallow breathing
  • Difficulty in breathing
  • Coughing
  • Fever
Based on a physical examination, your doctor may make a tentative diagnosis of atelectasis and may call for further tests to confirm the diagnosis. Tests include chest x-rays, chest CT scans chest MRI scans and bronchoscopy.

In many cases, the cause of the obstruction can be seen in a chest x-ray. However, a computed tomography (CT) scan is usually considered to be a superior diagnostic tool as it can provide valuable information such as the exact location and the extent of the blockage. It can also help the doctor distinguish between benign and malignant tumors that are causing the obstructive atelectasis. Magnetic resonance imaging (MRI) scans can help provide additional information if needed.

Treatment for obstructive atelectasis aims to re-expand the collapsed portion of the lung. The treatment options include:

  • Chest Physiotherapy: These exercises help people to breathe deeply after a surgery and can help normalize the affected lung. They include clapping, a technique involving clapping on the chest to loosen any mucus plugs that may be causing the obstruction. Incentive spirometry devices may also be used during these exercises.
  • Body Position: Lying down so that your head is at a lower level than your chest will help the mucus drain from the bottom of the lungs. This is known as postural drainage.
  • Oxygen Therapy: Supplemental oxygen may be provided to help relieve acute shortness of breath.
  • Medications may be administered in some cases. Bronchodilators such as Foradil may be used to open up the bronchial passages and make breathing easier. Acetylcysteine may help to thin mucus secretions and make it easier to cough. Dornase Alfa may be used to clear mucus in case of children suffering from cystic fibrosis.
  • Surgery: The removal of the cause of blockage from the bronchial airways may be undertaken with the help of a bronchoscope or by suctioning out the mucus. A bronchoscope uses a thin flexible tube which is threaded down the airways and helps to clear the airways.
  • Radiation and Chemotherapy: These may be used along with surgery to shrink the area of the tumor.
References:
  1. http://www.umm.edu/ency/article/000065all.htm
  2. http://www.ncbi.nlm.nih.gov/pubmed/8784731

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