Causes Of Atelectasis: Symptoms, Diagnosis And Treatment

Atelectasis is also called as collapse of lung. It is an imperfect expansion of the lung. It may be confined to a segment, a lobe or the whole lung.

It is also referred to as neonatal collapse. Non-aeration of lung at birth or developing soon after birth is not uncommon in premature or low birth weight babies because of under developed lungs.
It is also associated with neonatal hyaline membrane disease, laryngeal dysfunction and obstruction of air passage.

Acquired Causes Of Atelectasis

Acquired atelectasis is of 2 types:

Compression collapse: It occurs due to external compression of the lung as in pleural effusion, haemothorax, and pneumothorax or rarely by surgical procedures such as thoracoplasty.
Absorption collapse: It is more common and is produced by bronchial obstruction.
Intraluminal causes of obstruction are foreign body, inspissated mucus, tumors and aspirations of gastric contents e.g. during unconscious state or during anesthesia.
Causes within the wall of bronchus causing collapse include bronchial stricture, often due to tuberculosis or tumors.
Extrinsic causes: pressure on bronchus by enlarged lymph nodes, aortic aneurysm or enlarged left atrium may also lead to atelectasis.

A slowly developing atelectasis of a lobe may produce no symptoms.
A sudden or quick developing atelectasis is characterized by breathlessness and cough.
Massive atelectasis may be associated with cyanosis, tachycardia, restlessness and even circulatory collapse.
Limitation of chest excursion on the affected side and shift of trachea and heart to the same side.
Percussion note over collapsed area is impaired.
Bronchial breathing with bronchophony may be heard.
Massive atelectasis may be complicated by acute respiratory failure.
Repeated infections in atelectatic lobe may be present as recurrent pneumonia.

Chest X-ray usually confirms the diagnosis in form of a shrunken lung, lobe or segment. Displacement of the fissure, elevation of diaphragm and a change in position of mediastinal structures are important clues to underlying atelectasis.
Bronchoscopy is mandatory in all cases of obstructive collapse.
Examination of bronchial expirate for acid fast bacilli and cytology is necessary.
CT-scan helps to locate a mass or lymph node as the cause for atelectasis.

After a chest or major abdominal surgery deep breathing exercises, steam inhalation and encouragement to cough should be given to prevent post operative atelectasis.
Specific treatment depends upon cause of collapse. If effusion or pneumothorax is responsible, this external compression should be removed first.
Aspirated material, mucus plugs and foreign body need bronchoscopic removal.