Acute Laryngotracheobronchitis

A 3-year-old boy presents to the emergency department with a 2-day history of low-grade fever, rhinorrhea, and cough. Over the past 6 hours, he has developed a characteristic barky, seal-like cough and mild stridor at rest. His mother reports he was well until 48 hours ago when he developed upper respiratory symptoms. On examination, he is alert, maintaining oxygen saturation of 96% on room air, with a respiratory rate of 28/min. Auscultation reveals decreased air entry bilaterally with scattered rhonchi. There is no drooling or tripoding. What is the most appropriate initial management?

A 2-year-old girl is brought to the pediatric emergency department at 11 PM with a 3-day history of viral prodrome (fever, cough, rhinorrhea). For the past 4 hours, she has had progressive stridor, both inspiratory and biphasic, with moderate respiratory distress. Her respiratory rate is 38/min, oxygen saturation is 92% on room air, and she appears anxious and restless. She has received dexamethasone 0.6 mg/kg IV 2 hours ago but shows no improvement. Auscultation reveals bilateral air entry with mild wheezing. What is the next most appropriate step in management?