Hyperinflated lungs and mild perihilar interstitial markings

A term (41 weeks) female weighing 3100 g was born to a 30-year-old healthy gravida 2 para 1 mother by cesarean. Apgar scores were 9 and 9 at 1 and 5 minutes. The infant was initially well until day 3 of life, when she presented with tachypnea and increased work of breathing, including retractions and nasal flaring. The infant was transferred to the NICU. A complete sepsis workup was done and antibiotics were given as protocol. The infant was placed on a nasal cannula for oxygen saturation which ranged from 89-91%. A capillary blood gas was performed and revealed the following: pH 7.30, PaCO2 56 mm Hg, PaO2 45 mm Hg, HCO3 27 mEq/L, and BE 1.

A chest radiograph showed mild hyperinflated lungs and mild perihilar interstitial markings. An echocardiogram was also ordered at this time, which showed an anatomically normal heart with no structural malformation. During the next 24 hours, the infant’s respiratory status worsened, with progressive increases in work of breathing with increasing oxygen requirement. Continuous positive airway pressure was initiated by a nasal mask at 6 cm H2O and an FIO2 of 0.50.

A follow-up chest radiograph was performed, which showed increasing haziness of both lung fields with air bronchograms. Capillary blood gases obtained 12 hours after nasal CPAP therapy revealed the following: pH 7.19, PaCO2 80 mm Hg, PO2 40 mm Hg, HCO3 29.5 mEQ/L, BE 1.8, and oxygen saturation 88%. Physical assessment revealed the following: temperature 37.1°C, heart rate 175 beats per minute, respiratory rate 90 breaths per minute, and blood pressure 70/40 mm Hg. The infant was
intubated and mechanically ventilated with an inspiratory pressure of 20 cm H2O, PEEP of 6 cm H2O, a set rate of 60 breaths per minute, and FIO2 of 0.80. Systemic examination was unremarkable except for respiratory distress. There was no clinical evidence of pulmonary hypertension. A complete sepsis workup was repeated. The white blood cell count was unremarkable. Chest radiograph following intubation
revealed a diffuse ground-glass appearance with air bronchograms. The endotracheal tube was 2 cm above the carina.

1. What therapeutic recommendation would you make based on the infant’s clinical presentation and chest radiograph?
2. Given this presentation, what diagnosis should be considered for this infant?
3. What information obtained by chest radiograph would indicate that this infant may benefit from
surfactant replacement
therapy?