initial radiographs demonstrate intubation of the right mainstem bronchus with repeat radiographs demonstrating the positioning of the endotracheal tube currently <num> cm above the level of the carina. for more appropriate placement, recommend retraction approximately <num> cm. opacification of the left lower lobe with volume loss and leftward shift of mediastinal structures most compatible with partial left lower lobe collapse in keeping with right mainstem bronchus intubation.