Pneumothorax and air-leak syndromes — formative SAQs

SAQ 1 (10)

A 16-year-old, tall and slim, presents with sudden left-sided pleuritic chest pain and breathlessness at rest. He has no known lung disease. On examination he is speaking in sentences and haemodynamically stable, with reduced breath sounds and a hyper-resonant percussion note on the left. [5] [2]

1. State the features that would tell you this is a tension pneumothorax and how that would change your immediate action. (3) [2]
2. Assuming he is stable, outline how you would confirm and size the pneumothorax and decide on treatment. (4) [1]
3. State two pieces of advice you would give him at discharge to reduce recurrence and future risk. (3) [5]

Model answer

Tension features and action. Tension pneumothorax is suggested by severe respiratory distress, hypoxia, hypotension and tachycardia, distended neck veins, tracheal deviation away from the affected side, and unilateral absent breath sounds. If present, it is a clinical diagnosis: I would give high-concentration oxygen and decompress immediately with a needle or finger thoracostomy followed by a chest drain, without waiting for a chest X-ray. In this stable boy those features are absent, so I can image first. [2]

Confirm, size and treat. I would confirm with an erect chest radiograph showing the visceral pleural line with absent lung markings beyond it, using the rim of air to grade size — a rim greater than two centimetres at the hilum defines a large leak. Point-of-care lung ultrasound is a useful bedside adjunct. For a small, stable, minimally symptomatic primary spontaneous pneumothorax, conservative management with oxygen and observation is appropriate and non-inferior; a larger or symptomatic leak is managed with needle aspiration or a small-bore chest drain, with ambulatory options in selected patients. [1] [2]

Discharge advice. Stop smoking and vaping, as both strongly increase recurrence; avoid diving permanently unless cleared and avoid unpressurised air travel until reviewed and the lung has fully re-expanded; and return immediately with recurrent chest pain or breathlessness because same-side recurrence is common. [5] [1]

SAQ 2 (10)

A ventilated 27-week preterm infant with respiratory distress syndrome suddenly desaturates. The blood pressure falls, the left chest transilluminates brightly, and breath sounds are reduced on the left. [7] [10]

1. State your interpretation and the immediate management. (4) [7]
2. Explain the Macklin mechanism by which alveolar air can produce pneumothorax, pneumomediastinum and interstitial emphysema. (3) [10]
3. State two ventilation-related measures that reduce the risk of further air leak in this infant. (3) [7]

Model answer

Interpretation and immediate management. This is a tension pneumothorax in a ventilated neonate — a sudden desaturation with falling blood pressure, unilateral reduced breath sounds and bright transillumination. It is treated on clinical grounds: give high-concentration oxygen, decompress with needle aspiration and then place an intercostal chest drain to an underwater seal, matching needle length and site to the infant's thin chest wall so the pleura is reached without injuring deeper structures. Resuscitate the circulation in parallel. [7] [10]

Macklin mechanism. An overdistended alveolus ruptures at its base under high transpulmonary pressure. The escaping air dissects along the perivascular and peribronchial sheaths toward the hilum, producing pneumomediastinum, and from there can rupture into the pleural space as a pneumothorax or track into the neck as surgical emphysema. When air remains trapped within the interstitial planes of the lung it forms pulmonary interstitial emphysema, a marker of barotrauma and a precursor to larger leaks. [10] [7]

Ventilation measures. Use a lung-protective strategy with the lowest effective peak and mean airway pressures and appropriate positive end-expiratory pressure to limit overdistension; consider high-frequency ventilation and, for localised interstitial emphysema, lateral decubitus positioning of the affected side. Optimising surfactant and avoiding excessive tidal volumes further reduces ongoing barotrauma. [7] [10]