Miscellaneous topics | Respiratory system | Pathology

Bronchiectasis: It is irreversible, abnormal dilatation of the bronchi and bronchioles. It typically results from damage to bronchial walls from infections like Staphylococci, Klebsiella, Mycobacteria etc. and follows a chronic course. It is often associated with cystic fibrosis, Kartagener’s syndrome, lung cancers, COPD and allergic bronchopulmonary aspergillosis. Some cases may be congenital. It may be cylindrical, varicose or cystic. Bronchial secretions cannot be cleared in bronchiectasis which leads to secondary infections. Bronchiectasis presents with cough and expectoration, hemoptysis, dyspnea, clubbing etc. CxR will show dilated bronchi, “tram-track” opacities, increased bronchovascular markings and air-fluid levels. HRCT is the investigation of choice for diagnosis.

Pneumothorax and atelectasis: Pneumothorax is the abnormal accumulation of air in the pleural space. It may lead to partial or complete atelectasis or collapse of the lungs. Pneumothorax may be primary or secondary. Primary spontaneous pneumothorax is caused by the rupture of subpleural blebs. It is more common in tall, young men and in smokers. Mutations in the FLCN gene that codes for folliculin protein and acts as a tumor suppressor gene and also is involved with connective tissue formation, are associated with primary spontaneous pneumothorax.

Secondary spontaneous pneumothorax is seen in underlying disorders of the lung such as emphysema, COPD, asthma, TB, bronchiectasis etc. Systemic disorders such as rheumatoid arthritis, ankylosing spondylitis, polymyositis and dermatomyositis, systemic sclerosis, Marfan’s syndrome and Ehlers-Danlos syndrome can also cause secondary spontaneous pneumothorax.

Traumatic pneumothorax is seen following penetrating trauma to the chest. It can occur following gunshot or stab wounds, or as a complication of invasive procedures such as subclavian vein catheterization, lung biopsy etc. It may be associated with mechanical ventilation.

Tension pneumothorax is a life-threatening form of pneumothorax where the defect in the lung is such that it acts as a one-way flap-valve allowing air to flow in, but not flow out, leading to air trapping under high pressure. With each inspiration, more high tension air collects in the pleura, interfering with venous return to the heart and causing atelectasis and shock. On examination, breath sounds are absent on the affected side, trachea is deviated to the opposite side, JVP is elevated and the point of maximal impulse is shifted laterally.

Pneumothorax presents with sudden onset of dyspnea, chest tightness, pleuritic chest pain, hypoxia. Cardiorespiratory collapse is seen in tension pneumothorax.

For treating tension pneumothorax, a large-bore needle should be inserted into the 2nd intercostal space in the midclavicular line, as an emergency procedure, even before an X ray is taken. It should be followed by tube thoracostomy. Any penetrating chest wounds should be sealed immediately. In primary spontaneous pneumothorax, treatment is dependent on presentation and the size of the pneumothorax. If the size of the pneumothorax is <50% of the hemithorax and the patient is asymptomatic, then observation can be done as there are good chances of spontaneous regression. In secondary spontaneous pneumothorax, high flow oxygen is given and conservative management is done if the size is small i.e. 1 cm or less air rim. Aspiration and chest tube drainage can be done for more severe cases. Serial chest X rays are done to monitor response. CxR shows absent lung markings, most commonly seen at the apices in an upright patient. “Deep sulcus sign” is seen when air collects in the inferior sulci. In addition, collapsed lung and mediastinal shift is seen in tension pneumothorax.
Hemothorax: It is the accumulation of blood in the pleural cavity. Causes are trauma, ruptured aortic aneurysm, malignancy, anticoagulants etc. It may occur with a pneumothorax. Tension hemothorax may cause lung compression and mediastinal displacement to the opposite side. CxR looks like pleural effusion with blunting of costophrenic angle, air-fluid interface.
Pulmonary contusion: Contusion is characterized by parenchymal damage with alveolar haematoma and edema and damage to interstitial tissues of the lung. It is caused by chest trauma, traffic accidents, deceleration injury, blast injuries etc. It presents with hypoxia, dyspnea, tachypnea, tachycardia, chest pain, hemoptysis, atelectasis, ARDS, respiratory failure. Reduced breath sounds are heard on auscultation. CxR (not sensitive in early stages), chest ultrasound or CT scan help in diagnosis. CxR shows patch consolidation which are ill-defined and non-segmental and may be confused with pneumonia.