A 7-month-old boy is brought to the emergency department due to progressive difficulty bre… — USMLE Step 2 CK

A $7$ -month-old boy is brought to the emergency department due to progressive difficulty breathing and poor feeding over the past $24$ hours. One week ago, he had a mild upper respiratory tract infection that seemingly resolved. Currently, the infant is lethargic and sweating heavily during attempts to feed. Vital signs show a temperature of $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), heart rate of $178/\text{min}$ , respiratory rate of $68/\text{min}$ , and blood pressure of $65/40 \text{ mmHg}$ . Oxygen saturation is $93\%$ on room air. Physical examination reveals marked intercostal retractions. Lung auscultation demonstrates diffuse wheezing and bilateral basilar crackles. Cardiac examination reveals tachycardia, a prominent $S_3$ gallop, and a grade $2/6$ holosystolic murmur at the apex. The liver edge is palpated $4 \text{ cm}$ below the right costal margin. Capillary refill time is $4$ seconds, and peripheral pulses are weak in all extremities. A chest radiograph demonstrates severe cardiomegaly with pulmonary venous congestion. Which of the following is the most appropriate next step in management?

Initiation of intravenous milrinone and furosemideAnswer
B
Administration of nebulized hypertonic saline and nasal suctioning
C
Administration of inhaled albuterol and systemic corticosteroids
D
Administration of intravenous ceftriaxone and azithromycin
E
Obtain a high-resolution computed tomography scan of the chest

Answer

Initiation of intravenous milrinone and furosemide

The correct answer addresses the patient's acute decompensated heart failure and cardiogenic shock. This infant is exhibiting classic signs of pediatric heart failure, likely due to viral myocarditis given the recent viral prodrome. Presenting signs include respiratory distress, diaphoresis during feeding (equivalent to exertional dyspnea in infants), a prominent

S_3

gallop, and right-sided fluid overload manifesting as hepatomegaly. The hypotension and delayed capillary refill indicate cardiogenic shock. The immediate priority is to improve cardiac output and relieve pulmonary venous congestion using an inotrope (such as milrinone or epinephrine) and a diuretic (such as furosemide).

Step-by-Step Solution

Analyze the patient's clinical presentation and vital signs.

The infant presents with lethargy, diaphoresis with feeding, severe tachycardia (

178/\text{min}

), tachypnea (

68/\text{min}

), hypotension (

65/40 \text{ mmHg}

), and prolonged capillary refill (

4

seconds).

These findings are indicative of hemodynamic instability and cardiogenic shock.

Synthesize the physical examination and imaging findings.

The presence of a prominent

S_3

gallop, an apical holosystolic murmur, significant hepatomegaly, and a chest radiograph showing cardiomegaly with pulmonary venous congestion confirm cardiac dysfunction.

While wheezing and crackles can occur in primary respiratory conditions, these cardiac specific signs point to heart failure, likely secondary to viral myocarditis given the recent upper respiratory infection.

Determine the most appropriate immediate intervention.

The patient requires urgent inotropic support to improve cardiac contractility (e.g., milrinone) and diuretics to manage fluid overload (e.g., furosemide).

In acute decompensated heart failure with poor systemic perfusion, life-saving medical therapy must be initiated immediately before any further diagnostic imaging or non-cardiac treatments.

Key Concept

Acute decompensated heart failure and viral myocarditis in pediatric patients

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