Evaluate for alternative causes of symptoms
CXR
Thickening of airway walls and/or airway dilation
Linear perihilar densities, indistinctness of central pulmonary arteries
"Tram-track sign"; thickened, dilated airways perpendicular to x-ray beam
Elongated, tubular opacities due to mucus plugs
CT chest
Sensitive and specific
Airway dilation, signet ring sign (thickened, dilated airway adjacent to smaller artery
Lack of normal bronchial tapering-->visible medium bronchi extending out closer to pleura
"Tram-track" sign
Infectious workup
Consider sputum for TB
Diagnosis of cause generally outside ED scope but may include workup for cystic fibrosis, immunodeficiency, ciliary dysmotility
Thickening of airway walls and/or airway dilation
Linear perihilar densities, indistinctness of central pulmonary arteries
"Tram-track sign"; thickened, dilated airways perpendicular to x-ray beam
Elongated, tubular opacities due to mucus plugs
Sensitive and specific
Airway dilation, signet ring sign (thickened, dilated airway adjacent to smaller artery
Lack of normal bronchial tapering-->visible medium bronchi extending out closer to pleura
"Tram-track" sign
Consider sputum for TB
Bronchiectasis
Pulmonary
Acute bronchitis
Airway obstruction
Atypical pneumonia
Anaphylaxis
Bronchiolitis 
Angioedema