A previously healthy 13-month-old boy is brought to emergency one hour after acute-onset wheezing. His parents say they had guests over at the house and he was crawling on the floor beside the table when it started. On arrival, he is in respiratory distress and tachycardic. Blood pressure is stable. A chest x-ray shows atelectasis in the left upper lobe with a left-sided tracheal shift. Which of the following is the most appropriate next step in diagnosis?
Bronchoscopy
CT of the chest
Esophagogastroduodenoscopy
Upper GI series
Video-guided thoracentesis
