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Centre for Evidence-
Based Medicine

Diagnosis: Clinical Scenario

An infant is born at 30 weeks gestation, weighing 1560 grams. She requires endotracheal intubation and mechanical ventilation shortly after birth for respiratory distress syndrome. Ventilator pressure and the fraction of inspired oxygen are weaned nicely over the first three days following treatment with exogenous surfactant. However, on day four, the infant's need for ventilator and oxygen support increases. You suspect a patent ductus arteriosus (PDA) with left to right shunting. Treatment with indomethacin will be started if a PDA is confirmed. The senior resident wants to order an echocardiogram. You aren't sure that this is necessary and you wonder if the clinical exam is sufficiently accurate to diagnose a PDA.

You pose the clinical question, "In a preterm infant with a birth weight of 1560 grams, what is the accuracy of the clinical exam as a diagnostic test for PDA with left to right shunting?"

You perform a PubMed search using the MeSH terms "patent ductus arteriosus", "infant, premature", and "sensitivity and specificity". Of the 7 articles identified, only 2 compare clinical signs with echocardiography. You review both abstracts in PubMed and decide to copy the original article for the larger and more comprehensive study Arch Pediatr Adolesc Med 1995; 149: 1136-1141.

Read the article and decide:

  1. Is the evidence from this randomised trial valid?
  2. If valid, is this evidence important?
  3. If valid and important, can you apply this evidence in caring for your patient?

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