Sudden deterioration in a ventilated preterm — tension pneumothorax

Clinical information for the examiner

Setting: Tertiary NICU, day 2 of life. Infant is ventilated on synchronised intermittent mandatory ventilation (PIP 18, PEEP 5, rate 40, FiO₂ 0.30) for respiratory distress syndrome. Antenatal steroids were given; one dose of surfactant was administered at birth. [1]

On your arrival:

• Heart rate 80 bpm (was 145), SpO₂ 60% (was 95%), blood pressure 28/16 (mean 20, was 40). [9]
• Left hemithorax appears full and moves less than the right.
• Reduced air entry on auscultation of the left axilla.
• Apical impulse shifted toward the right.
• Capillary refill 4 seconds; infant is pale and poorly perfused. [1]
• Cold-light transillumination over the left anterior chest shows a bright halo. [9]

Task 1 — Focused assessment (3 marks)

The candidate should perform an ordered assessment. [1] [9]

1. Airway: confirm ETT position and patency (rule out the commonest cause of acute desaturation). [1]
2. Chest: asymmetry (full left hemithorax), reduced left air entry. [9]
3. Circulation: apical shift, hypotension, narrow pulse pressure, poor perfusion. [9]
4. Transillumination: bright left halo — confirms pneumothorax. [9]

Pass criterion: candidate identifies tension pneumothorax and does NOT call for a radiograph first. [9]

Task 2 — Emergency intervention (4 marks)

Emergency needle aspiration before radiograph. [9]

• 21–23 gauge butterfly or cannula. [9]
• Second intercostal space, mid-clavicular line, left side. [9]
• Aim just above the rib (avoid neurovascular bundle). [9]
• Three-way tap and syringe; aspirate air. [9]
• Confirm: hiss of air, immediate clinical improvement. [1]

Pass criterion: candidate states decompression before imaging and describes the technique with correct gauge, site, and above-the-rib direction. [9]

Task 3 — Definitive drain and management (3 marks)

• Because the infant is ventilated, a definitive chest drain is required (recurrence expected). [11]
• Pigtail catheter 8–10 Fr, Seldinger technique — less trauma, fewer complications than Malécot. [11]
• Connect to underwater seal; confirm position and re-expansion on radiograph. [9]
• Reduce ventilator pressures cautiously once decompressed. [1]
• Resuscitate with volume or inotrope for ongoing hypotension. [1]

Pass criterion: candidate names pigtail with advantage, underwater seal, and post-decompression radiograph. [11]

Task 4 — Pitfalls and prevention (2 marks)

Pitfall: misreading PIE as pneumothorax (bubbly non-shifting lucencies — do not drain) or missing an occult pneumopericardium in sudden arrest. [12]

Prevention bundle: antenatal steroids, early surfactant, synchronised volume-targeted ventilation, permissive hypercapnia, minimal PEEP, avoid mask over-ventilation. [4]