Deep Sulcus Sign Supine Pneumothorax

A 64-year-old man with severe CAP and ARDS is intubated on Day 4 in the ICU (PEEP 12, TV 6 mL/kg, FiO2 0.7). He has a 40-pack-year smoking history and moderate emphysema. Over 5 minutes, his SpO2 drops from 94% to 78%, HR rises to 130, systolic BP falls to 82, and peak airway pressures rise to 46 cmH₂O with HIGH PRESSURE alarm. Clinical examination reveals decreased right-sided expansion, hyper-resonant percussion, absent breath sounds, and tracheal deviation to the left. A supine portable chest X-ray is obtained. The structure marked **A** in the diagram—an abnormally deep hyperlucent right costophrenic angle (deep sulcus sign)—is visible. Which of the following is the MOST APPROPRIATE immediate management in this clinically obvious tension pneumothorax?