Case 3: The Hypothermic Newborn

A 2-day-old male infant born at 38 weeks to a gravida 1, para 1 woman is brought to the emergency department secondary to concerns for hypothermia, poor feeding, and decreased urine output. Prenatal laboratory results are unremarkable, with the exception of group B Streptococcus colonization that was adequately treated with penicillin prophylaxis before delivery. The delivery course was notable for thick meconium for which the infant underwent intubation and suctioning with subsequent extubation. The infant’s Apgar scores were 4 and 9 at 1 and 5 minutes, respectively. In the nursery, the infant was noted to be breastfeeding well and had passed stools and voided appropriately. He was discharged on day 2 after birth. After discharge, the parents contacted the infant’s physician to report decreased interest in feeding, decreased activity, and low rectal temperature of 93.9°F (34.4°C). The family was instructed to take the infant to the emergency department for further evaluation and treatment. On arrival at the emergency department, the infant was noted to have a temperature of 96.9°F (36.1°C) and to be listless, and was thus taken to a resuscitation bay. Initial physical examination showed an ill-appearing infant with tacky mucous membranes and an exaggerated Moro reflex. He was given a 10-mL/kg normal saline bolus and a 15-mL/kg normal saline bolus. Initial laboratory findings include the following: white blood cells 22,000/μL(22×109/L); hemoglobin 13.3 g/dL (133 g/L); hematocrit 36.5%; platelet count, 565×103/μL (565×109/L); neutrophils 80%; bands 1%; lymphocytes 12%; monocytes 5%; sodium 154 mEq/L (154 mmol/L); potassium 5.1 mEq/L (5.1 mmol/L); chloride 115 mEq/L (115 mmol/L); bicarbonate 20 mEq/L (20 mmol/L); blood …