Twenty minutes after delivery by lower segment cesarean section at 38 weeks' gestation, a 4630-g (10-lb 3-oz) male newborn has respiratory distress. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. The newborn's temperature is 36.9°C (98.4°F), pulse is 155/min; and respirations are 72/min. Pulse hree hours after delivery, circumoral cyanosis was noted after the infant was breastfed. Pulse oximetry readings were 98% in the right hand and 83% in the left foot. On physical examination, the patient has subcostal retractions and grunting. Cardiac examination reveals a 2/6 systolic murmur at the left lower sternal border. Femoral pulses are strong bilaterally. Which of the following is the most likely cause of this infant's cyanosis?

Question

Twenty minutes after delivery by lower segment cesarean section at 38 weeks' gestation, a 4630-g (10-lb 3-oz) male newborn has respiratory distress. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. The newborn's temperature is 36.9°C (98.4°F), pulse is 155/min; and respirations are 72/min. Pulse hree hours after delivery, circumoral cyanosis was noted after the infant was breastfed.  Pulse oximetry readings were 98% in the right hand and 83% in the left foot.  On physical examination, the patient has subcostal retractions and grunting.  Cardiac examination reveals a 2/6 systolic murmur at the left lower sternal border.  Femoral pulses are strong bilaterally.  Which of the following is the most likely cause of this infant's cyanosis?

Quizplus · Accepted Answer

Eductional Objective: Differential cyanosis (ie, postductal < preductal oxygen saturation) in a neonate suggests right-to-left shunting across a patent ductus arteriosus, such as in persistent pulmonary hypertension of the newborn (PPHN).  Patients with PPHN typically have an underlying pulmonary disorder with respiratory distress and strong femoral pulses.

Twenty Minutes After Delivery by Lower Segment Cesarean Section at 38