Important differentials:
1)CROUP: Non-toxic, viral prodrome, barking cough X-ray neck shows steeple sign
2)EPIGLOTTITIS: toxic child, drooling saliva Lateral X-ray neck shows thumb sign
3)DIPHTHERIA: cervical lymph nodes (bull neck), dirty grey/ white membrane, and un- immunized
4)FOREIGN BODY ASPIRATION: Choking, decreased air entry, unilateral hyperinflation