Review Question - QID 214728

A 2-year-old boy is brought to the emergency department by his parents because of difficulty breathing. He developed a mild fever, runny nose, and a high-pitched, dry cough that worsened 2 nights ago. Earlier today, his parents noticed that his breathing became “noisy” particularly when he inhaled and were worried when it persisted even during rest. He is otherwise healthy, is up-to-date on immunizations, and takes no medications. His older sister has asthma. His temperature is 101.7°F (38.7°C), blood pressure is 100/70 mmHg, pulse is 140/min, and respirations are 34/min. Pulse oximetry on room air shows an oxygen saturation of 97%. On physical exam, the infant appears lethargic. A high-pitched inspiratory stridor is heard at rest. He exhibits nasal flaring and subcostal retractions. On auscultation, there are coarse breath sounds and diminished air movement bilaterally. Skin tone and turgor are normal. A chest radiograph is shown in Figure A. Which of the following is the most appropriate next step in management?