A 3-year-old boy is brought to the emergency department by his mother with a 6-hour history of sudden onset coughing and difficulty breathing. She reports he was playing with peanuts in the living room when he suddenly started coughing violently. On examination, he is anxious, with stridor present. Chest auscultation reveals diminished breath sounds on the right side with hyperresonance to percussion. Chest X-ray (inspiratory) shows hyperinflation of the right lung with mediastinal shift to the left. What is the most appropriate immediate management?