PresentationA preterm (28 weeks of gestation) male infant develops recurrent episodes of apnea and severe cyanosis on day 11 after birth. The infant is born to a 39-year-old, gravida 4, para 3, living 3 mother by emergency caesarian section because of pathologic results of a nonstress test. The mother received a course of antenatal corticosteroids 12 hours before delivery. The antenatal period had been uncomplicated with normal results of fetal imaging targeted for anomalies. There are no antenatal risk factors for sepsis. Previous pregnancies were uneventful. The infant cries immediately after birth and has Apgar scores of 7, 8, and 8 at 1, 5, and 10 minutes, respectively. The infant weighs 1,080 g at birth and has respiratory distress syndrome for which he receives surfactant and continuous positive airway pressure (CPAP) for 4 days. On day 1, he is given parenteral nutrition and minimal enteral nutrition. Feeds are gradually increased, and he reaches full feeds by age 7 days. After the central catheters are removed, the infant is moved to the step-down nursery. The infant is feeding well with no sign of feeding intolerance or sepsis. On the 11th day, the infant has recurrent episodes of apnea initially requiring bag and mask, then CPAP, and finally mechanical ventilation. On examination, the infant is euthermic and has a heart rate of 175 beats per minute, a respiratory rate of 70 breaths per minute, prolonged capillary refill time (approximately 5 seconds), good pulse volume, moderate to severe intercostal and subcostal retractions, central and peripheral cyanosis, oxygen saturation of 30% in room air, no crepitations or wheeze, no appreciable murmur, liver 2 cm below the costal margin, and sensorium depressed with a flat anterior fontanel. The infant is prescribed antibiotics, fluids, and inotropic support. Even with 100% oxygen with mechanical ventilation, the infant continues to be cyanotic and has persistent oxygen saturations of 40% to 50%. Preductal and postductal saturation difference is 15%. Transillumination test rules out pneumothorax, and chest radiography reveals normal inflation, no infiltrates, and no collapse or effusions. The infant develops seizures with clonic movements in the left upper limb for which he is prescribed phenobarbitone. In view of suspected pulmonary hypertension, the infant is prescribed milrinone. Laboratory investigation reveals an increased total white blood count of 33,000/mL (33.0 Â 10 9 /L), a platelet count of 430,000/mL (43.0 Â 10 9 /L), a C-reactive protein level of 82 mg/L (781.0 nmol/L), and normal serum glucose, calcium, and electrolyte levels. Arterial blood gas analysis reveals severe metabolic acidosis with the following values: pH, 7.08; PCO 2 , 24 mm Hg; base excess, À17 mEq/dL; and sodium bicarbonate, 5.7 mEq/dL. The infant is given a bicarbonate infusion. The results of head ultrasonography are normal. Electrocardiography reveals sinus tachycardia, right axis deviation, and tall peaked P waves. At this stage 1, investigation clinched the diagnosis.
