Case 1: Absent Lower Limb Pulses in a Neonate

Abstract

A 3-kg term male infant is born to a 26-year-old primigravida woman after 5 years of primary infertility secondary to polycystic ovary syndrome. Vacuum extraction is performed for fetal distress, and the infant is resuscitated with positive pressure ventilation and chest compressions for 60 seconds. In the NICU, mechanical ventilation is initiated. The first blood gas measurement 10 minutes after birth reveals a pH of 6.6, partial pressure of carbon dioxide of 64 mm Hg (8.5 kPa), partial pressure of oxygen of 100.8 mm Hg (13.4 kPa), and bicarbonate of 5.4 mEq/L (5.4 mmol/L). Systemic hypothermia is initiated for perinatal asphyxia with moderate encephalopathy. He develops features of poor perfusion 6 hours after birth and is resuscitated with 2 normal saline boluses. A dobutamine infusion is started, followed by epinephrine infusion for refractory shock. Packed red blood cells are transfused, because the hematocrit is only 35% (0.35) and the infant has a subgaleal hemorrhage. He is given phenobarbitone, phenytoin, and levetiracetam, and later midazolam infusion for refractory seizures. In view of the refractory shock, systemic hypothermia is discontinued and the infant is rewarmed over a period of 8 hours. As his perfusion improves, it is noted that the femoral pulses are weaker than the brachial pulses, with systolic blood pressures 20 mm Hg higher in the upper limbs. The infant is suspected to have critical coarctation of the aorta and a prostaglandin infusion is started. However, an echocardiography at the bedside shows a normal thoracic aorta and aortic arch. A computed …