An 11-day-old neonate presented with difficulty in breathing, poor feeding and sweating during feeding. O/E Weak femoral pulse Radial pulse -bounding Radio-femoral delay Loud S2 Systolic ejection clicks or thrill in the suprasternal notch Sho systolic murmur was heard along the left sternal border at the 3rd and 4th intercostal spaces transmitting to the left infrascapular area and to the neck. ABG of lower limbs revealed severe acidosis as compared to the upper limbs. SpO2 (upper limb)> SpO2 (lower limb) Chest X-ray Which of the following needs to be given urgently to the neonate to save the life of the neonate: –

**Core Concept**
The neonate's presentation suggests a congenital heart defect with altered circulation, leading to differential cyanosis. This is likely due to a patent ductus arteriosus (PDA) with a left-to-right shunt, causing desaturation of systemic blood and acidosis in the lower limbs.

**Why the Correct Answer is Right**
The presence of a loud S2, systolic ejection clicks, and a short systolic murmur along the left sternal border, transmitting to the left infrascapular area and neck, is suggestive of a PDA. The radio-femoral delay and bounding radial pulse indicate aortic runoff. The severe acidosis and differential cyanosis in the lower limbs confirm the diagnosis of a PDA with a left-to-right shunt. Prostaglandin E1 (PGE1) is given urgently to maintain the patency of the ductus arteriosus, ensuring adequate pulmonary blood flow and systemic circulation.

**Why Each Wrong Option is Incorrect**
**Option A:** **Dobutamine** would increase cardiac contractility but would not address the underlying cause of the PDA.
**Option B:** **Nitric oxide** is used in pulmonary hypertension but would not be effective in this scenario.
**Option C:** **Indomethacin** is used to close a PDA, but in this case, the PDA needs to be kept open to ensure adequate circulation.

**Clinical Pearl / High-Yield Fact**
In neonates with suspected congenital heart disease, a patent ductus arteriosus (PDA) can be diagnosed by the presence of a continuous murmur ("machinery" murmur) and differential cyanosis between the upper and lower limbs.

**Correct Answer:** C. Indomethacin is given to close the PDA, but in this case, Prostaglandin E1 is given to keep the PDA open.

✓ Correct Answer: A. PGE1