An 8-month-old infant girl is evaluated in the pediatric clinic during mid-winter for a th… — USMLE Step 2 CK

An 8-month-old infant girl is evaluated in the pediatric clinic during mid-winter for a three-day history of nasal congestion and a subjective low-grade fever. Today, her parents noticed that she developed a raspy cough and is breathing faster than usual. She has been feeding slightly less than normal but continues to have an adequate number of wet diapers. Her medical history is unremarkable, and she is up to date on all recommended immunizations. On physical examination, her temperature is $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ ), heart rate is $135/\text{min}$ , respiratory rate is $56/\text{min}$ , and oxygen saturation is $95\%$ on room air. The infant appears mildly fussy but is easily consolable. Auscultation of the chest reveals diffuse expiratory wheezing and scattered crackles bilaterally, accompanied by mild subcostal retractions. Which of the following is the most appropriate next step in the management of this patient?

Provide supportive care with nasal suctioning and hydrationAnswer
B
Initiate inhaled bronchodilator therapy
C
Start oral amoxicillin therapy
D
Administer a single dose of oral dexamethasone
E
Administer the intranasal live-attenuated influenza vaccine

Answer

The most appropriate next step is providing supportive care with nasal suctioning and hydration.

This patient's clinical presentation is classic for acute viral bronchiolitis, a lower respiratory tract infection most commonly caused by Respiratory Syncytial Virus (RSV) that primarily affects infants and toddlers younger than 2 years. It typically begins with a viral prodrome (nasal congestion, rhinorrhea, mild fever) that progresses over 2 to 3 days to lower respiratory tract involvement, marked by tachypnea, increased work of breathing (retractions), diffuse expiratory wheezing, and crackles. Because the pathogenesis involves viral-induced epithelial necrosis, sloughing, and copious mucus production rather than pure bronchospasm, the diagnosis is made clinically, and management is entirely supportive. For an infant who is well-hydrated and maintaining adequate oxygenation (typically defined as oxygen saturation

\geq 90\%

on room air), the best next step is providing supportive care with nasal suctioning (to clear the upper airway and facilitate feeding) and ensuring adequate hydration.

Step-by-Step Solution

Analyze the patient's age, symptom timeline, and physical examination findings.

The patient is an infant presenting in winter with a viral prodrome (rhinorrhea, low-grade fever) followed by lower respiratory tract signs (tachypnea, wheezing, retractions, and crackles).

Identifying the classic clinical presentation is necessary to establish the diagnosis of acute viral bronchiolitis, most commonly caused by Respiratory Syncytial Virus (RSV).

Evaluate the severity of the respiratory distress.

The infant has mild tachypnea and retractions but is maintaining an oxygen saturation of

95\%

on room air and is adequately hydrated (normal urine output).

Assessing severity determines whether the patient requires hospital admission (e.g., for hypoxia, dehydration, or apnea) or can be managed safely in the outpatient setting.

Select the appropriate evidence-based intervention.

Supportive care (hydration and nasal suctioning) is chosen as the standard of care. Pharmacologic interventions are excluded.

Current pediatric guidelines explicitly recommend against the routine use of bronchodilators, corticosteroids, and antibiotics for the treatment of typical viral bronchiolitis.

Key Concept

Diagnosis and management of acute viral bronchiolitis in infants.

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