A 19-month-old boy is evaluated in the emergency department in mid-January for a 4-day his… — USMLE Step 2 CK

A 19-month-old boy is evaluated in the emergency department in mid-January for a 4-day history of nasal congestion, low-grade fever, and a worsening cough. Over the past 24 hours, his parents noted rapid breathing and poor oral intake. His medical history includes severe atopic dermatitis. Both parents have persistent asthma. He has had one previous episode of wheezing at 14 months of age during a viral illness. He is up to date on all recommended childhood immunizations.

His temperature is $38.1^\circ\text{C}$ ( $100.6^\circ\text{F}$ ), pulse is $158/\text{min}$ , respiratory rate is $62/\text{min}$ , and oxygen saturation is $88\%$ on room air.

Physical examination reveals a tired-appearing toddler with marked subcostal and intercostal retractions, nasal flaring, and a prolonged expiratory phase. Copious yellowish-green mucus is noted in the nares. Lung auscultation demonstrates diffuse polyphonic wheezing and coarse crackles bilaterally.

A chest radiograph shows generalized hyperinflation, peribronchial cuffing, and a wedge-shaped opacity in the right upper lobe without air bronchograms.

A trial of nebulized albuterol is administered. Forty-five minutes later, his respiratory rate is $64/\text{min}$ , oxygen saturation is $88\%$ on room air, and the wheezing is unchanged.

Which of the following is the most appropriate next step in the management of this patient?

A
Administration of oral dexamethasone and transition to continuous albuterol nebulization
B
Empirical administration of intravenous ceftriaxone and azithromycin
Admission for supplemental oxygen therapy and supportive careAnswer
D
Prescription for oral prednisolone and discharge home with a short-acting beta-agonist inhaler
E
Administration of intravenous furosemide and strict fluid restriction

Answer

Admission for supplemental oxygen therapy and supportive care

The patient has severe acute viral bronchiolitis, characterized by a viral prodrome, wheezing, crackles, and severe respiratory distress. Despite a strong Asthma Predictive Index (atopic dermatitis, parental asthma, prior wheezing), the lack of clinical response to an albuterol trial confirms that the airway obstruction is driven by bronchiolar epithelial sloughing and mucus plugging rather than smooth muscle bronchospasm. According to AAP guidelines, bronchodilators and systemic corticosteroids are ineffective and not recommended for bronchiolitis. The right upper lobe opacity represents focal atelectasis from mucus plugging—a classic finding in bronchiolitis—not a bacterial lobar pneumonia. Therefore, antibiotics are contraindicated. The most appropriate next step is admission for supportive care, including supplemental oxygen for his severe hypoxia (

88\%

on room air) and close monitoring.

Step-by-Step Solution

Analyze the clinical presentation and patient history

A 19-month-old with a viral prodrome, severe respiratory distress, hypoxia (

88\%

SpO2), diffuse wheezing, and crackles. He has a strong family and personal history of atopy.

Establishes a differential diagnosis heavily centered on acute viral bronchiolitis versus an early-onset asthma exacerbation.

Interpret the response to therapeutic intervention

The patient showed zero clinical or objective improvement following a trial of nebulized albuterol.

Lack of reversibility points away from smooth muscle bronchospasm (asthma) and confirms airway obstruction due to epithelial sloughing and mucus plugging (bronchiolitis).

Evaluate the chest radiograph findings

Hyperinflation and a wedge-shaped opacity without air bronchograms in the setting of a viral illness.

Confirms focal atelectasis secondary to mucus plugging, which is a hallmark of bronchiolitis and does not require antibiotics.

Select the guideline-concordant management step

Hospital admission for supportive care, including supplemental oxygen and hydration.

AAP guidelines strictly advise against the use of bronchodilators, systemic corticosteroids, and antibiotics in the routine management of acute bronchiolitis, emphasizing supportive care for hypoxemic patients.

Key Concept

Differentiating severe acute bronchiolitis from an asthma exacerbation in young toddlers with atopic risk factors, and strictly adhering to supportive management guidelines despite confounding variables.

Estimated Time:2m 0s

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