Links between early adrenal function and respiratory outcome in preterm infants: Airway inflammation and patent ductus arteriosus

Objective. To investigate the relationship of cortisol concentrations during the first week of life to patent ductus arteriosus (PDA), markers of lung inflammation, and respiratory outcome in very low birth weight infants. Methods. Newborns <1500 g birth weight were prospectively enrolled at 2 centers. Serum cortisol was measured 3 times during days 2 to 7 of life. Tracheal lavage was performed on intubated infants and analyzed for interleukin-1 beta, -6, and -8, and for total protein, albumin, and alpha-1 protease inhibitor. Infants receiving prenatal glucocorticoids were excluded. Results. We obtained 337 cortisol values from 125 infants. Infants treated for PDA had lower cortisol values after day 2. One hundred thirty-three tracheal fluid samples were obtained on matching days from 71 intubated infants. Cortisol correlated inversely with tracheal interleukins and proteins. Lower cortisol values during the second half of the week correlated with longer duration of supplemental oxygen therapy and with subsequent development of chronic lung disease at 28 days and at 36 weeks. Conclusion. Infants with lower cortisol values in the first week of life had an increased incidence of PDA, increased lung inflammation, and an increased incidence of chronic lung disease. These findings suggest that early adrenal insufficiency may underlie the previously observed association of increased lung inflammation and PDA with adverse respiratory outcome in this population.