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Pediatric Hospital Medicine

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Pediatric Hospital Medicine Curriculum

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Newborn Care Complex Conditions Procedures Patient/Family-Centered Care Transitions of Care Patient Safety Quality Improvement Evidence-Based Care Advocacy and Leadership Ethics, Legal, Human Rights Teaching and Education Research and Biostatistics

The Anatomy of a Didactic Question


A 10-month-old boy is admitted for hydration in the setting of emesis and poor oral intake. His illness began with fever and a maculopapular rash on the distal extremities, as well as watery, foul-smelling stools. His rash and diarrhea have resolved, but he continues to have a low-grade fever and poor energy. Since yesterday, he has had four episodes of emesis and is feeding poorly, taking a maximum of 2 ounces of liquid at a time. He received 20 cc/kg of isotonic fluid resuscitation prior to admission. On examination, the infant is sleepy with a low-grade fever, heart rate of 130 bpm, respiratory rate of 30 breaths per minute, normal blood pressure, and normal oxygen saturation. Extremities are cool. An additional 20 cc/kg of normal saline is ordered. Halfway through the bolus, his nurse calls with concern that his heart rate and respiratory rate have both increased, and his oxygen saturation has begun briefly dropping to 88% on room air. On repeat examination, perfusion remains poor, and blood pressure is 66/37 mm Hg. Crackles are present in both lung bases, and a liver edge is palpated 3 centimeters below the costal margin. Which of the following tests is most likely to be abnormal?

Answer choice options
  • A. Blood culture.
  • C. Liver function tests.
  • D. Stool culture.
  • B. Echocardiogram.

The incorrect options (distractors) are not totally wrong. These options can be diagramed as follows:

Most Correct
Least Correct
  • B.
    Echocardiogram.Will show decreased systolic function of the myocardium.
  • A.
    Blood culture.Obtained for suspected sepsis, however given worsening clinical status after fluid administration, less likely to be sepsis.
  • C.
    Liver function tests. The liver may be enlarged, but is likely functioning normally.
  • D.
    Stool culture.Indicated in suspected bacterial gastroenteritis. Clinical presentation more consistent with cardiogenic shock.

The Anatomy of an Explanation

This infant has findings of shock, a state of inadequate perfusion to meet the nutrient and oxygen needs of tissue. Hypovolemia is the most common cause of shock among children, and this infant’s history of diarrhea, emesis, poor feeding, and poor perfusion raises concern for hypovolemia. However, the infant had an unexpected response to fluid administration. Namely, his heart rate increased, and he developed respiratory distress, hypoxia, pulmonary rales, and hepatomegaly. His presentation is highly concerning for cardiogenic shock. Cardiogenic shock is caused by pump failure and resultant decreased cardiac output. Viral myocarditis is an important cause of cardiogenic shock in children. In contrast to other forms of cardiomyopathy that present subacutely, myocarditis may sometimes present with fulminant cardiac failure and acute cardiogenic shock. In young infants, the myocarditis often develops concurrently during an acute viral infection, while older children and adolescents are more likely to develop subacute symptoms of heart failure after the viral syndrome has resolved. The myocardial inflammation of myocarditis results in decreased cardiac output and consequent congestive heart failure. The heart failure manifests as nonspecific symptoms such as poor feeding, decreased energy, fussiness, and respiratory distress and sometimes rapid progression of hemodynamic collapse. Examination findings of tachycardia, tachypnea, and pallor may initially be concerning for other types of shock, such as hypovolemia and sepsis. Hepatomegaly and rales may also be present before or after fluid resuscitation, and these findings are not consistent with either hypovolemia or sepsis. Initial evaluation should include chest radiography, which may demonstrate cardiomegaly and increased pulmonary vascular markings, as well as an electrocardiogram, which demonstrates nonspecific findings such as decreased QRS or T wave voltages, inverted T waves, and nonspecific ST changes. The rhythm is typically sinus tachycardia. Elevated troponins may indicate myocardial injury, and increased brain natriuretic peptide indicates heart failure. An echocardiogram confirms suspicion for decreased systolic function of the myocardium. The echocardiogram is also used to exclude other structural causes of left ventricular dysfunction, as well as thrombi. Pulmonary hypertension may be present if left ventricular dysfunction is severe. Mitral and tricuspid regurgitation and a pericardial effusion may also be present. Cardiac catheterization is sometimes undertaken for the purpose of endocardial biopsy and diagnosis of treatable etiologies of cardiac dysfunction. Due to the risk associated with endocardial biopsy, however, cardiac magnetic resonance imaging may also be used to establish a diagnosis. Testing for viral and autoimmune conditions should be based on the patient’s presentation.

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