Chest decompression and intercostal drain insertion — branching viva

Emergency department: an 8-year-old hit by a car is agitated, cyanosed, tachypnoeic, with reduced air entry and hyperresonance on the right, tracheal deviation to the left, distended neck veins, and a blood pressure of 70/40. The examiner asks for the diagnosis, the immediate decompression site and technique, and why you would not wait for imaging — then branches to the safe triangle and the bundle rule for the definitive drain, to the weight-based lidocaine dose, to the ventilated neonate who suddenly deteriorates, and finally to a loculated empyema in a 3-year-old.