**Question:** The most appropriate management for maintaining patency of ductus arteriosus in a neonate is -

A. Propranolol
B. Indomethacin
C. Nifedipine
D. Salbutamol

**Correct Answer:** B. Indomethacin

**Core Concept:**
Ductus arteriosus (DA) is a fetal shunt that allows oxygen-rich blood to bypass the pulmonary circulation and reach the systemic circulation. In preterm infants, the DA typically closes within the first few days after birth due to the production of prostaglandins and prostacyclin, which keep the DA open. However, in infants born at term, the DA usually closes within the first week as the pulmonary vessels mature and the need for a direct shunt diminishes.

**Why the Correct Answer is Right:**
Infants with a patent ductus arteriosus (PDA) may develop hemodynamically significant PDA, where the shunt size is large enough to cause hemodynamic compromise. Indomethacin is a non-selective cyclooxygenase (COX) inhibitor that blocks the production of prostaglandins (PGI2, PGE2, and thromboxane A2) and prostacyclin (PGI2) that keep the DA open. By inhibiting these prostaglandins, Indomethacin helps to close the DA.

**Why Each Wrong Option is Incorrect:**
A. Propranolol (beta-blocker): While beta-blockers can be used to manage other conditions in neonates, they are not indicated for PDA closure as they do not affect prostaglandins, which are responsible for maintaining ductal patency.

C. Nifedipine (calcium channel blocker): Nifedipine is typically used to manage hypertension in adults. Unlike Indomethacin, it does not specifically target prostaglandins involved in maintaining ductal patency.

D. Salbutamol (beta-agonist): Salbutamol is used to treat bronchoconstriction and asthma, not PDA closure. It does not interfere with prostaglandin production.

**Clinical Pearls:**
Infants with hemodynamically significant PDA should be evaluated for potential causes, such as congenital heart disease, hypothyroidism, or sepsis. If a PDA is not hemodynamically significant and does not cause left-to-right shunting, it may not require treatment.

**Explanation of Core Concepts:**
Intermittent or continuous indomethacin therapy is used to close the PDA. Indomethacin is a non-selective COX inhibitor, which reduces the production of prostaglandin E2, I2, and prostacyclin, which are responsible for maintaining ductal patency. By inhibiting these prostaglandins, Indomethacin helps to close the ductus arteriosus.