MSFinals-4600

A 3-day-old neonate born at term is presenting with tachypnoea, grunting, and cyanosis. The baby is unable to feed and has an oxygen saturation of 70% on room air. On auscultation, a loud S2 and systolic murmur are heard, which is loudest at the left sternal border. The doctors suspect transposition of the great arteries and have started the baby on intravenous fluids, antibiotics, and scheduled surgery. What additional medication should be given in the meantime?