A 1-hour-old boy is admitted to the neonatal intensive care unit for respiratory failure. The infant was born to a 27-year-old mother, gravida 4 para 2, at 29 weeks gestation via cesarean delivery due to maternal preeclampsia with severe features. Amniotic fluid was clear. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. Birth weight is 1,120 g (2 lb 8 oz) . Temperature is 36.9 C (98.4 F) , pulse is 170/min, and respirations are 56/min. Pulse oximetry is 82% on room air. There are intercostal and subcostal retractions. Cardiac examination shows tachycardia without murmurs. The lungs have decreased breath sounds bilaterally. The abdomen is soft without organomegaly. Surfactant is ordered, and the team prepares for intubation. Prior to these clinical interventions, which of the following best describes the condition of this patient's lungs compared to a normal neonate?

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11ec160b_3b3d_cdf8_9249_35b76d441a7d_MD0001_00 This preterm infant has increased work of breathing, hypoxia, and decreased breath sounds, findings which are concerning for neonatal respiratory distress syndrome (RDS). RDS is caused by immaturity of type 2 pneumocytes, resulting in lack of alveolar surfactant. Without surfactant, the alveoli have increased surface tension and therefore decreased compliance. These poorly compliant alveoli are prone to collapse, resulting in widespread atelectasis that lowers functional residual capacity and total lung capacity. Surfactant deficiency also results in pneumocyte injury and lung inflammation; the resulting edema can narrow the airways and increase airway resistance (Choice A). RDS is treated with respiratory support and exogenous surfactant via an endotracheal tube, which transiently improves pulmonary compliance while the type 2 pneumocytes mature and begin to release endogenous surfactant. After surfactant administration, infants have increased lung expansion (ie, total lung capacity, functional residual capacity) and decreased airway resistance (Choice E). (Choice C) Decreased compliance, increased functional residual capacity, and increased airway resistance is the pattern seen in newborns with meconium aspiration syndrome. This obstructive process presents with respiratory distress at birth due to air trapping in the distal airways but would be unlikely in this patient with a history of clear amniotic fluid. (Choice D) Increased compliance with decreased functional residual capacity and airway resistance is suggestive of pulmonary air leak (eg, pneumothorax), which causes respiratory distress at birth due to air within the extraalveolar space. Chest asymmetry and asymmetric breath sounds would be expected. Educational objective: Respiratory distress syndrome classically presents in premature infants with increased work of breathing and hypoxia at birth due to surfactant deficiency. Poor alveolar compliance leads to widespread atelectasis and decreased functional residual capacity. Airway resistance is often increased due to lung inflammation and edema.

A 1-Hour-Old Boy Is Admitted to the Neonatal Intensive Care