Diagnosis

Croup

Etiology

Cause [pv7]

• Parainfluenza virus (the most common cause)

• Other virus: influenza A and B, adenovirus, rhinovirus, SARS-CoV-2, respiratory syncytial virus, measles.

• Rare viruses: enteroviruses (coxsackie, echovirus, herpes simplex)

• Bacterial infection (rare): Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, Corynebacterium diphtheria

Pathophysiology [pv7]

1. Infection in the larynx, trachea, and bronchi

2. Edema and mucus in narrow airways (children)

3. Barking cough and inspiratory stridor

Complications [pv7]

• Bacterial tracheitis

• Pneumonia

• Pulmonary edema

• Death (rare)

Epidemiology

Incidence per 100.000 [m2s][qsc][dys][uhp]

Approach

• Clinical diagnosis 

• Blood test

• Nasal test

• Laryngoscopy (direct or fiberoptic)

• Bronchoscopy

• X-ray collum (lateral neck)

Treatment

1. Mild: usually a self-limited infection [bfp]

   • Humidified air

   • Elevated head

   • Continuous airway, respiratory rate, and heart rate observation

   • Fever: NSAIDs, Paracetamol

2. Severe: stridor, hypoxia, sternal wall retractions [bfp][pv7]

   • Oxygen

   • Dexamethasone 0.15-0.6 mg/kg (maximum 10 mg) or prednisolone 1 mg/kg [qsc]

   • Epinephrine

   • Intubation <1%

   • Heliox (mixture of helium and oxygen)

   • Antiviral neuraminidase inhibitors if influenza A or B 

   • Antibiotics if bacterial infection is suspected

Differential diagnoses

Acute laryngitis, Allergy, Angioedema, Benign vocal cord lesion, Diphtheria, Epiglottitis, Foreign body, Gastroesophageal reflux disease, Inhalation injury, Laryngomalacia, Measles, Mononucleosis, Peritonsillar abscess, Retropharyngeal abscess, Sarcoidosis, Subglottic stenosis, Tracheomalacia, Vocal cord immobility, Wegener's granulomatosis