Treatment of Barking Cough in a 9-Month-Old Infant
For a 9-month-old infant with a barking cough suggestive of croup, give a single dose of oral dexamethasone 0.15-0.60 mg/kg immediately, and add nebulized epinephrine (0.5 ml/kg of 1:1000 solution) if the infant has stridor at rest or any signs of respiratory distress. 1, 2, 3
Immediate Assessment and Differential Diagnosis
Before treating as croup, rapidly exclude life-threatening conditions:
- Rule out pertussis first in this age group, as barking cough with post-tussive vomiting is a hallmark of Bordetella pertussis infection, which is particularly dangerous in infants under 6 months but remains serious at 9 months 1, 4
- Consider foreign body aspiration if there is sudden onset of respiratory distress without fever or preceding upper respiratory symptoms 5
- Exclude bacterial tracheitis, epiglottitis, and retropharyngeal abscess if the infant appears toxic or has high fever 2, 6
Primary Treatment for Croup
Dexamethasone is the cornerstone of treatment:
- Give 0.15-0.60 mg/kg as a single oral dose for all severities of croup, including mild disease 1, 2, 3
- The oral route is preferred and equally effective as intramuscular administration 3
- Onset of action is approximately 6 hours, so symptoms may not improve immediately 6
Add nebulized epinephrine for moderate-to-severe croup:
- Indications include stridor at rest, respiratory distress, oxygen saturation <92-93%, or respiratory rate >70 breaths/min 1, 7
- Dose: 0.5 ml/kg of 1:1000 solution (racemic epinephrine) via nebulizer 1, 8
- Provides rapid symptom relief within minutes but requires monitoring for rebound obstruction for at least 2 hours after administration 6, 3
Hospitalization Criteria
Admit the infant if any of the following are present:
- Requires three or more doses of nebulized epinephrine 1
- Oxygen saturation <92-93% 1
- Age under 18 months (this 9-month-old is high-risk) 1
- Respiratory rate >70 breaths/min 1
- Stridor at rest or signs of exhaustion 7
Special Consideration: Pertussis
If pertussis is suspected (paroxysmal cough with post-tussive vomiting):
- Start azithromycin immediately—this is the preferred macrolide for infants 1-5 months and appropriate for this 9-month-old 1, 4
- Hospitalize if pertussis is confirmed or strongly suspected, as infants under 12 months have the highest risk of life-threatening complications 1, 4
- Implement contact tracing and prophylaxis for household contacts 1
Treatments NOT Recommended
- Do not use humidification therapy—it has not been proven beneficial despite historical use 2
- Do not routinely order laboratory studies or radiographs unless alternative diagnoses are suspected 3
Clinical Pitfalls
The most critical error is missing pertussis in an infant presenting with barking cough, as the mortality risk is substantial in this age group and treatment differs significantly from viral croup 1, 4. Always ask about immunization status and presence of post-tussive vomiting or inspiratory "whoop."