Neonatal air-leak syndromes — formative SAQs

SAQ 1 — The deteriorating ventilated preterm (10 marks)

A 27-week gestation, 850 g infant is day 2 of life, ventilated for respiratory distress syndrome on synchronised intermittent mandatory ventilation. The nurse calls you because the infant has suddenly desaturated to 60%, the heart rate has fallen to 80, and the peak inspiratory pressure has risen. The left hemithorax appears full and moves less than the right. Blood pressure is 28/16. [9]

a) What is the most likely diagnosis, and what single bedside test supports it at the cot side? (2 marks) [9]

The most likely diagnosis is a left tension pneumothorax in a ventilated preterm infant with sudden deterioration, reduced left air entry, a full hemithorax, and cardiovascular compromise (hypotension, bradycardia). The single bedside test is cold-light fibreoptic chest transillumination, which will show a bright halo over the left hemithorax. [9]

b) Describe your immediate management, including the specific technique you would use and why you would not await imaging. (4 marks) [9]

The immediate management is emergency needle aspiration of the left hemithorax before any radiograph. This infant is unstable (hypotensive, bradycardic) with a clear clinical picture and a clear transillumination halo — the standard is to decompress first and image after. [1] [9]

Technique: insert a 21 to 23 gauge butterfly needle or cannula into the second intercostal space in the mid-clavicular line on the left, aiming just above the rib to avoid the neurovascular bundle, connected to a three-way tap and syringe, and aspirate air. [9] The hiss of escaping air and immediate clinical improvement confirm the diagnosis.

c) After initial decompression, what definitive procedure is required, and describe one modern device and its advantage over the traditional alternative? (2 marks) [11]

Because the infant is ventilated, the pneumothorax will recur once the needle is removed, so a definitive chest drain is required. The modern device is a pigtail catheter (8–10 French, Seldinger technique), whose advantage over the traditional Malécot chest drain is less tissue trauma, a smaller incision, and fewer complications (lung injury, bleeding, phrenic nerve injury). [11]

d) State the prevention bundle that reduces the risk of air leaks in preterm infants, citing the evidence base. (2 marks) [4]

The prevention bundle comprises antenatal corticosteroids, early surfactant for RDS, synchronised and volume-targeted ventilation, permissive hypercapnia with minimal effective PEEP, and avoidance of mask over-ventilation in the delivery room. [4] [6] [7] The evidence base is a chain of Cochrane reviews showing reduced air leaks with each element.

SAQ 2 — A bubbly lung that is not a pneumothorax (10 marks)

A 25-week, 680 g infant is day 5 of life, ventilated for RDS and a patent ductus arteriosus. Over 12 hours the oxygen requirement has risen from 30% to 55%, the PaCO₂ has risen from 48 to 72 mmHg, and ventilator settings have been increased to maintain chest rise. There has been no single abrupt event. The chest radiograph shows hyperlucent streaks and cyst-like lucencies radiating from both hila. [12]

a) What is the diagnosis, and which radiographic feature distinguishes it from a pneumothorax? (3 marks) [12]

The diagnosis is pulmonary interstitial emphysema (PIE). The bubbly, streaky, cyst-like lucencies radiating from the hila are characteristic. The key distinguishing feature from a pneumothorax is that the lucencies do not change with posture — a lateral decubitus film confirms they are fixed in the interstitium, unlike pleural air, which shifts. [12]

b) Why would inserting a chest drain be the wrong intervention, and what is the correct management principle? (3 marks) [3]

Inserting a chest drain is wrong because the air is within the lung interstitium, not in the pleural space — a drain does not evacuate interstitial air and may lacerate the already-injured lung. [12] This misreading is a classic error. The correct management principle is to lower the mean airway pressure and change the ventilation strategy, because PIE is a marker of ventilation-induced lung injury. [3]

c) Outline the ventilation strategy changes you would consider. (2 marks) [3]

Consider switching to high-frequency oscillatory ventilation to achieve gas exchange at lower tidal volumes and lower mean pressures, permissive hypercapnia to reduce minute-ventilation requirements, and, for localised PIE, lateral decubitus positioning with the affected side down to splint the leak. [3]

d) What are the longer-term prognostic implications of PIE in this infant? (2 marks) [12]

PIE in the very preterm is strongly associated with bronchopulmonary dysplasia (chronic lung disease), prolonged ventilation, and increased mortality. [12] The infant is also at risk of intraventricular haemorrhage from fluctuating intrathoracic pressures and pCO₂, and requires neurodevelopmental and respiratory follow-up. [3]