Question

Parents bring their 8-month-old male infant to the pediatric clinic due to worsening noisy breathing and new-onset feeding difficulties. The infant has had a "raspy" breathing sound since he was approximately 2 months old. The parents note that the noise occurs constantly during both inspiration and expiration, and it becomes significantly louder when the infant cries. Over the past four weeks, since the introduction of pureed solid foods, he has frequently gagged and regurgitated during meals. The parents report that he seems to breathe most comfortably when he sleeps with his head arched backward, and his breathing worsens if his chin is pushed toward his chest. He has no history of fever, cough, or sick contacts. His immunizations are up to date. Temperature is 37.0°C (98.6°F), pulse is 128/min, respirations are 32/min, and oxygen saturation is 98% on room air. Physical examination reveals a well-nourished infant with biphasic stridor. Auscultation of the lungs reveals clear breath sounds bilaterally with no wheezing or crackles. The stridor does not improve when the infant is placed in the prone position.

Which of the following is the most appropriate next step in the evaluation or management of this patient?