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.
Symptoms Of 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.
How To Diagnose Atelectasis?
- 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.
Treatment Options 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.