26th April 2024

A 6-month-old infant, previously healthy, is brought to the emergency department with a history of sudden onset of difficulty breathing.

A 6-month-old infant, previously healthy, is brought to the emergency department with a history of sudden onset of difficulty breathing. The infant was noted to be playing normally but then suddenly became unresponsive and turned blue. On examination, the infant is limp, with a respiratory rate of 8 breaths per minute, heart rate 180 bpm, and oxygen saturation of 85% on room air. There is no audible wheezing, and chest examination reveals poor air entry bilaterally.

Which is the most likely diagnosis?