Atelectasis is the partial or complete collapse of a lung due to deflation of air in the alveoli.
Types of atelectasis
| Type | Description |
|---|---|
| Obstructive atelectasis | Due to blockage within the airways. It is also known as absorptive atelectasis. |
| Non-obstructive atelectasis | Due to pressure from outside the lungs |
| Adhesive atelectasis | Due to decreased surfactant levels |
| Rounded atelectasis (Blesovsky or folded lung syndrome) | Due to pleural disease, e.g., asbestosis. The thickened pleura causes lung tissue to invaginate |
| Post-operative atelectasis | Due to shallow breathing patterns after thoracic or abdominal surgery. It commonly occurs 72 hours after surgery. The mechanism is a combination of obstruction and compression. |
| Cicatriziation atelectasis | Due to lung fibrosis or scarring |
| Relaxation atelectasis | This occurs when the lung loses contact with the chest wall, e.g., pneumothorax |
| Replacement atelectasis | This occurs when the alveoli are replaced by tumour tissue |
| Middle lobe syndrome | This is recurrent collapse of the right middle lobe or lingula |
- Causes
- Postoperative atelectasis
- General anaesthesia
- Pain which limits deep breathing and coughing
- Muscle relaxants which reduce lung volumes
- Obstructive atelectasis
- Non-obstructive atelectasis
- Enlarged lymph nodes (hilar lymphadenopathy)
- Pleural effusion
- Adhesive atelectasis
- Plumonary contusion
- Pneumonia
- Aging
- Neonatal distress syndrome
- Postoperative atelectasis
- Risk factors
- Surgery
- Thoracic surgery
- Cardiac surgery
- Upper abdominal surgery
- Peri-operative risk factors
- General anaesthesia (90%)
- Muscle relaxants
- High FiO2
- Poor pain control
- Opioids
- Mechanical ventilation
- Obesity
- Pregnancy
- Prolonged immobilisation
- Surgery
- Pathophysiology
- Basilar segments are more likely to collapse in supine patients
- Airway obstruction → absorption of air distal to the obstruction → decreased alveolar volume → collapse
- External compression → increased intrathoracic pressure prevents alveoli from expanding during inspiration
- Loss of surfactant → increased surface tension → alveolar collapse
- Epithelial injury and apoptosis → fluid leakage into alveolar spaces
- Signs and Symptoms
- Mild fever
- Crackles on auscultation
- Reduced breath sounds
- Cyanosis in severe cases
- Mediastinal shift towards the affected side
- Dullness on percussion
- Pleuritic chest pain
- Cough
- Tachypnoea
- Investigations
- Chest X-ray
- Linear poacitis
- Loss of lung volume
- Elevated hemidiaphragm
- Tracheal shift towards the affected side
- Fissure displacement
- Pulmonary opacity
- CT scan of the chest is more sensitive than chest X-ray
- Loss of lung volume
- Dependent lung colapse
- Bronchoscopy for mucus plug, foreign body and endobronchial tumors. It can be diagnostic and therapeutic.
- Arterial blood gas (ABG) analysis
- Hypoxaemia
- Respiratory alkalosis
- Normal or low PaCO2
- Chest X-ray
- Treatment
- Oxygen if indicated
- Lung re-expansion strategies
- Incentive spirometry
- Chest physiotherapy
- Acapella device
- Early ambulation or mobilisation
- Upright positioning
- Positive pressure ventilation when indicated
- Tracheal suction or bronchoscopy to clear the airway
- Mucolytics may help in specific cases