Review Question - QID 109493

A 3-month-old female presents to the emergency department because her mother is concerned about her breathing. The patient’s mother reports that the patient has been breathing “loudly” for several weeks. The noise seems to be worse when the patient is prone during tummy time. The patient is also having increasing difficulty during feedings and cannot take the same quantity of milk as before. The patient was born at 39 weeks gestation via vaginal delivery. Prenatal testing during the pregnancy was unremarkable, and the patient has otherwise been doing well since birth. Her temperature is 98.6°F (37°C), blood pressure is 77/56 mmHg, pulse is 119/min, and respirations are 23/min. His oxygen saturation is 98% on room air. On physical exam, the patient is in no acute distress. She has inspiratory and expiratory stridor that improves when her neck is tilted backward. Her lungs are clear to auscultation bilaterally. The patient’s chest radiograph can be seen in Figure A. The patient is scheduled for a CT scan of the neck and chest to confirm the diagnosis. This patient should undergo which of the following screening tests?