A 68-year-old man with COPD is intubated in the ICU for respiratory failure. Post-intubation chest X-ray shows the endotracheal tube tip positioned 28 cm at the incisors. On examination, the patient has asymmetric breath sounds with diminished left-sided air entry and elevated airway pressures. The structure marked **A** in the diagram is the likely site of tube malposition. Which of the following is the most appropriate immediate management?

Explanation

The structure marked **A** (right main bronchus) is shorter, wider, and more vertical (~25° from midline) than the left main bronchus (~45°). This anatomical difference makes the right mainstem bronchus the preferential site for deep endotracheal tube insertion. In this case, the tube at 28 cm (beyond the typical safe depth of 23–24 cm in adult men) has likely entered the right mainstem bronchus, causing selective right lung ventilation, left lung atelectasis, and asymmetric breath sounds with elevated airway pressures. The immediate management is simple withdrawal of the tube 2–3 cm followed by reassessment of bilateral breath sounds and capnography waveform to confirm return to tracheal positioning. This is the standard bedside correction for right mainstem intubation and avoids unnecessary procedures. Bronchoscopy is invasive and reserved for cases where bedside correction fails or tube position remains uncertain after clinical reassessment. Tube replacement and CT imaging are not indicated for straightforward malposition correction. **High-Yield:** Right mainstem intubation is corrected by simple withdrawal 2–3 cm + clinical reassessment (bilateral breath sounds + capnography); confirm tracheal tube position at 3–5 cm above carina on CXR (T2–T4 level). [cite: Gray's Anatomy 42e Ch 56; Harrison 21e Ch 287]