Q. A 3-year-old female presents to the emergency department with chief complaints of cough and fever. Her mother reports the child has been sick for the past 4 days, and that her symptoms became significantly worse this morning. The patient was previously healthy and takes no medications regularly, and her immunizations are up to date. Both her appetite and activity levels are described as decreased. She lives at home with 2 brothers, who are both healthy, and she attends daycare 3 days/week. Her mother denies any known sick contacts. On physical examination, her temperature is 38.5 degrees Celsius (101.3 Fahrenheit), heart rate 120/min, respiratory rate 60/min, blood pressure 100/50 mm Hg. She appears mildly toxic, but is not cyanotic. No rashes or lesions are noted. Her ears, nose, and throat examination is unremarkable. Retractions, grunting, and accessory muscle use are noted on her lung examination. Localized rales and wheezing are detected over the right lower lung fields. Which of the following interventions will provide the most useful information at this time?