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A 3 week old infant that is positive for RSV has had several prolonged episodes of apnea requiring BVM ventilation. The decision is made to intubate the baby. It is a difficult intubation, although the tube is finally observed to pass through the cords on video laryngoscopy. A 3.5 uncuffed tube has been placed and taped at 12cm at the lip. After several positive pressure breaths on 100% FiO2, the pulse oximetry has fallen to 85% and fails to rise. The ETCO2 waveform is normal and reading 46 mm Hg. Heart rate is 170, BP is 62/30. On auscultation breath sounds are decreased on the left side. Trachea is midline.

What is the best next step?