A 1-hour-old girl is evaluated in the nursery for respiratory distress. Her mother had an uncomplicated pregnancy. At 38 weeks gestation, the mother had rupture of membranes with clear fluid. Two hours later during induction of labor, nonreassuring fetal heart abnormalities were noted, and an emergency cesarean delivery was performed. Temperature is 37.2 C (99 F). Pulse oximetry is 95% on 1 L oxygen via nasal cannula. Pulmonary examination reveals tachypnea, nasal flaring, intercostal retractions, and clear breath sounds. Cardiac examination shows tachycardia with normal heart sounds; femoral pulses are 2+ bilaterally. The abdomen is soft with no hepatosplenomegaly. Complete blood count is normal, and blood culture is pending. Chest x-ray reveals increased lung volumes and fluid in the interlobar fissures. Which of the following is the most likely etiology of this patient's symptoms?

Question

A 1-hour-old girl is evaluated in the nursery for respiratory distress.  Her mother had an uncomplicated pregnancy.  At 38 weeks gestation, the mother had rupture of membranes with clear fluid.  Two hours later during induction of labor, nonreassuring fetal heart abnormalities were noted, and an emergency cesarean delivery was performed.  Temperature is 37.2 C (99 F).  Pulse oximetry is 95% on 1 L oxygen via nasal cannula.  Pulmonary examination reveals tachypnea, nasal flaring, intercostal retractions, and clear breath sounds.  Cardiac examination shows tachycardia with normal heart sounds; femoral pulses are 2+ bilaterally.  The abdomen is soft with no hepatosplenomegaly.  Complete blood count is normal, and blood culture is pending.  Chest x-ray reveals increased lung volumes and fluid in the interlobar fissures.  Which of the following is the most likely etiology of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d724_9b39_bc81_6be7118bd3d3_MD0003_00 This term newborn with increased work of breathing and fluid-filled fissures has transient tachypnea of the newborn (TTN), a condition caused by delayed resorption and clearance of pulmonary fluid. Normally, alveolar liquid produced during lung development is later absorbed by mature fetal lungs into the interstitial space and ultimately the pulmonary vasculature. This resorption is driven by increased catecholamine signals in late gestation and markedly increases during labor. Therefore, patients born prematurely or by cesarean delivery are at increased risk of TTN. Excess pulmonary fluid can cause respiratory distress (eg, tachypnea, grunting, retractions) and hypoxia in newborns in the first few hours after delivery. Breath sounds are often clear in patients with TTN as most of the fluid is in the interstitial space rather than in the alveoli. Findings on chest x-ray (eg, hyperinflation, fluid in interlobar fissures) confirm the diagnosis, and patients are treated supportively (eg, supplemental oxygen). TTN usually resolves spontaneously within a few hours to days as passive fluid resorption is completed. chest x-ray (Choice A) Aspiration of infected amniotic fluid due to maternal chorioamnionitis causes bacterial pneumonia. Neonatal pneumonia also presents with respiratory distress; however, crackles and an infiltrate on chest x-ray would be expected. (Choice B) Bronchiolar obstruction from thickened mucus is seen in patients with cystic fibrosis (CF). Neonates with CF can have meconium plugs in the gastrointestinal tract, but chronic pulmonary infections and bronchiolar obstruction do not occur in the newborn period. (Choice C) Chemical irritation and airway obstruction occur with meconium aspiration syndrome, which presents at delivery with respiratory distress associated with meconium-stained amniotic fluid. Hyperinflation and patchy infiltrates are seen on x-ray. (Choice E) Intrapleural and extrapleural pressures equalize in patients with a pneumothorax, which typically presents with asymmetric breath sounds and air in the pleural space on x-ray. (Choice F) Immature lung development and surfactant deficiency cause respiratory distress syndrome (RDS) in premature infants. RDS can be differentiated from TTN by low lung volumes, ground-glass opacities, and air bronchograms on chest x-ray. RDS is rare in term infants, such as this newborn. respiratory distress syndrome (RDS) Educational objective: Transient tachypnea of the newborn is a self-limited condition caused by delayed resorption and clearance of pulmonary fluid and is more common in infants delivered by cesarean section. Infants present shortly after birth with respiratory distress and fluid in the interlobar fissures on chest x-ray. References: Respiratory distress in the newborn. (http://www.ncbi.nlm.nih.gov/pubmed/25274969)

A 1-Hour-Old Girl Is Evaluated in the Nursery for Respiratory