Chest decompression and intercostal drain insertion — formative SAQs

SAQ 1 (10 marks)

A previously well 8-year-old boy is brought to the emergency department after being struck by a car at speed. He is agitated, markedly tachypnoeic, and cyanosed. Examination reveals reduced air entry and hyperresonance over the right hemithorax, a trachea deviated to the left, and distended neck veins; his blood pressure is 70/40 mmHg. There is no time for imaging. ^{[3] [4]}

1. State the diagnosis and outline the immediate management, including the exact site and technique for needle decompression and why you would not wait for a chest radiograph. (4) ^[3]
2. Describe the definitive intercostal drain insertion that must follow: name the safe triangle borders, the bundle rule, and your drain size for this child. (3) ^[1]
3. Forty minutes later the drain is swinging and bubbling but the child's haemoglobin is now 72 g/L and 250 mL of blood has drained in the last hour. Outline your ongoing management and the indication for thoracotomy. (3) ^[9]

Model answer — SAQ 1

(1) Diagnosis and immediate needle decompression (4). The diagnosis is a right tension pneumothorax, made clinically from the combination of respiratory distress, hypoxia, reduced air entry and hyperresonance on the right, tracheal deviation away from the affected side, distended neck veins, and circulatory collapse. Tension pneumothorax is a clinical diagnosis — I decompress immediately and do not wait for a chest radiograph, because waiting costs venous return and the child is peri-arrest. I give high-flow oxygen, secure intravenous access, and give a 10 mL/kg isotonic crystalloid bolus while I decompress in parallel. I insert a large-bore (14 or 16 gauge) cannula at the second intercostal space in the mid-clavicular line on the right, or — increasingly preferred, especially in children — at the fourth or fifth intercostal space in the anterior axillary line within the safe triangle; the axillary site is preferred because the paediatric chest wall is thinner and more consistent there and the catheter is more likely to reach the pleural space. I insert perpendicular to the skin, advance until air rushes out (the hiss), withdraw the needle, and leave the cannula secured. The needle is only a bridge: a formal intercostal drain must follow within minutes. ^{[3] [4] [5]}

(2) Definitive drain — safe triangle, bundle rule, drain size (3). I place the definitive intercostal drain within the triangle of safety: the anterior border is the lateral edge of pectoralis major, the posterior border is the lateral edge of latissimus dorsi, the inferior border is the fifth intercostal space at the nipple line, and the apex is the base of the axilla. I enter in the fourth or fifth intercostal space in the anterior axillary line and I insert just above the rib below — the intercostal neurovascular bundle runs in the costal groove along the inferior border of the rib above, so passing above the lower rib keeps me clear of it. I use blunt dissection (never a trocar), keep a finger in the track, and connect immediately to an underwater seal with the tube tip two centimetres below the water line. For this 8-year-old with a traumatic pneumothorax and possible haemothorax I would choose a large-bore 28 to 32 French drain so that any blood does not clot and block the tube; if it were purely air I would use a small-bore 8 to 14 French pigtail. ^[1]

(3) Ongoing blood loss and the thoracotomy threshold (3). The combination of ongoing drainage, falling haemoglobin, and shock signals a significant haemothorax. I cross-match blood, transfuse to maintain perfusion, and reassess constantly. The indication for thoracotomy in a child is ongoing heavy blood loss — broadly, more than 2 mL/kg per hour of continued drainage, or a large initial volume — or haemodynamic instability despite drainage and transfusion. A prospective multicentre cohort analysis of traumatic haemothorax identified a large initial volume and persistent bleeding as the predictors of initial management failure that should trigger surgical review. I involve the trauma and thoracic surgical teams early and continue the ATLS primary survey for associated injuries. ^[9]