Question 123

Question:

A baby is born tachypneic and cyanotic with Sa02 80% in the upper extremities and 99% in the lower extremities. The hypoxemia does not respond to 100% oxygen and a congenital heart defect is suspected. Emergent cardiac catheterization reveals transposition of the great vessels. Which of the following can be given to the baby to maintain a patent ductus arteriosus until surgical correction can be performed?

Correct Answer: B.  PGE2

Prostaglandins are formed through the arachidonic acid cascade in response to several stimuli, including inflammatory mediators. Each prostaglandin has several, and often antagonistic effects. PGE1 maintains a patent ductus arteriosus (PDA) even in a normal neonate for up to a week. In the case of transposition of the great vessels, this communication between pulmonary and arterial circulation is crucial to rescue the abnormally separated pulmonary and systemic circulations. During fetal development, a PDA is maintained to bypass the high resistance, non-respirating pulmonary circulation. This is one of the reasons NSAIDs, which block prostaglandin production, are contraindicated during pregnancy.
PGD2 causes bronchodilation, platelet aggregation, and vasodilation.
PGI2 (prostacyclin) has similar effects as PGD2, with the addition of hyperalgesia and mucus secretion in the stomach.
PGF2 causes bronchoconstriction and myometrial contraction.
Main effects of PGE2 include increased renal blood flow and diuresis but is not responsible for the patent PDA.