✅ Model Answer:
• Visceral pleural line (white line) separating lung from pleural air.
• Absence of lung markings peripheral to the pleural line.
• Right lung collapse (volume loss).
• Mediastinal shift to the left (if tension).
• Deep sulcus sign (if supine).
• Diagnosis: Right-sided pneumothorax.

✅ Model Answer:
• Primary spontaneous pneumothorax: Rupture of apical subpleural blebs (tall thin males, smoking, family history).
• Secondary spontaneous pneumothorax: Underlying lung disease (cystic fibrosis, asthma, pneumonia, tuberculosis, Marfan syndrome, Ehlers-Danlos).
• Traumatic pneumothorax: Blunt or penetrating chest trauma, rib fractures.
• Iatrogenic: Central line insertion, mechanical ventilation, thoracentesis, lung biopsy.
• Catamenial pneumothorax: Associated with endometriosis (rare in adolescents).

✅ Model Answer:
• Sudden-onset sharp chest pain – pleuritic, ipsilateral.
• Shortness of breath – dyspnoea.
• Tachypnoea and tachycardia.
• Decreased breath sounds on the affected side.
• Hyperresonance to percussion.
• Tracheal deviation away from the pneumothorax (tension pneumothorax).
• Hypotension, hypoxia, and shock (tension pneumothorax).
• Subcutaneous emphysema (if associated with trauma).

✅ Model Answer:
• Tension pneumothorax: Air enters the pleural space but cannot escape → progressive accumulation → increased intrapleural pressure → mediastinal shift, compression of the contralateral lung, and reduced venous return → hemodynamic compromise.
• Features: Tracheal deviation away from the pneumothorax, distended neck veins, hypotension, hypoxia.
• Management: Immediate needle decompression (2nd intercostal space, midclavicular line) followed by chest tube insertion.
• Simple pneumothorax: No mediastinal shift, stable hemodynamics. Managed with observation, aspiration, or chest tube depending on size and symptoms.

✅ Model Answer:
• Diagnosis: Clinical (tracheal deviation, hypotension, hypoxia) + CXR (complete lung collapse, mediastinal shift).
• Management:
1. Immediate needle decompression: 14-16 gauge IV cannula in the 2nd intercostal space, midclavicular line on the affected side. A rush of air confirms placement.
2. Chest tube insertion (4th-5th ICS, anterior axillary line) after decompression.
3. Secure chest tube to underwater seal.
4. Monitor for re-expansion and complications.

✅ Model Answer:
• Size >2 cm (large) and symptomatic → drainage is indicated.
• Options:
- Simple needle aspiration: If successful and lung expands → observation.
- Small-bore chest tube (8-14 Fr) insertion with underwater seal.
• If aspiration fails or lung does not expand → chest tube.
• Admit to hospital for observation.
• Supplemental oxygen to enhance reabsorption of pleural air.
• If the patient is stable and the pneumothorax is small (<2 cm) and asymptomatic → observation with O2 and outpatient follow-up.

✅ Model Answer:
• Large pneumothorax (>2 cm on CXR) with symptoms.
• Failure of needle aspiration.
• Secondary pneumothorax (underlying lung disease).
• Traumatic pneumothorax.
• Tension pneumothorax (after needle decompression).
• Recurrent pneumothorax.
• Bilateral pneumothorax.
• Hemopneumothorax.
• Patient on mechanical ventilation.

✅ Model Answer:
• Measure the distance between the visceral pleural line and the chest wall at the level of the hilum.
• Small pneumothorax: <2 cm gap.
• Large pneumothorax: ≥2 cm gap.
• Alternatively, the Light index can be used: (1 - [lung width / hemithorax width]) × 100. >20% = large pneumothorax.
• In practice: If the lung edge is seen and the gap is <2 cm → small; if the gap is ≥2 cm → large.

✅ Model Answer:
• Supplemental oxygen (high-flow, 10-15 L/min via non-rebreather mask) increases the gradient between pleural and venous blood nitrogen → accelerates reabsorption of pleural air.
• Used in all patients with a pneumothorax, especially if symptomatic or hypoxic.
• May increase the rate of reabsorption by up to 4-fold.
• Monitor SpO2 and ensure adequate oxygen delivery.

✅ Model Answer:
• Recurrence rate: 30-50% within the first 2 years.
• Risk factors: Tall thin males, smoking, family history, younger age, large blebs.
• Prevention of recurrence:
- Pleurodesis: Chemical (talc, doxycycline, bleomycin) or surgical (VATS pleurodesis/pleurectomy).
- Bullectomy: Resection of apical blebs (VATS).
- Smoking cessation.
• Indications for pleurodesis: Recurrent pneumothorax, prolonged air leak, high-risk occupations (pilots, divers), bilateral pneumothorax.

✅ Model Answer:
• Deep sulcus sign: A radiographic finding seen in supine patients with a pneumothorax.
• The air in the pleural space accumulates anteriorly and laterally, causing the costophrenic angle to appear deeper and more lucent than normal.
• Indicates the presence of a pneumothorax in a supine patient (where the classic visceral pleural line may not be visible).
• Can be a subtle finding; may require a lateral decubitus view for confirmation.
• Seen in trauma patients, ICU patients, and neonates.

✅ Model Answer:
• This is a tension pneumothorax – a life-threatening emergency.
• Immediate management:
1. Needle decompression: 14-16 gauge IV cannula in the 2nd intercostal space, midclavicular line on the left side. A rush of air confirms placement.
2. After decompression, insert a chest tube (4th-5th ICS, anterior axillary line).
3. Connect to underwater seal.
4. Check CXR to confirm lung re-expansion.
5. If no improvement, consider other causes (e.g., obstruction, pulmonary embolism).