Randomized, double-blinded trial of low-dose dexamethasone: II. Functional residual capacity and pulmonary outcome in very low birth weight infants at risk for bronchopulmonary dysplasia.

We previously reported on a 7-day course of dexamethasone starting at 0.5 mg/kg/day in intubated very low birth weight (VLBW) infants, 7-14 days of age, with increased dynamic pulmonary compliance and decreased bronchopulmonary dysplasia (BPD). The effect of low-dose dexamethasone on functional residual capacity (FRC) in VLBW infants is unknown. The objective of this study was to compare the effect of two regimens of moderately early dexamethasone on FRC and passive respiratory compliance (Crs) in VLBW infants at risk for BPD. Sixty-two intubated VLBW infants were randomized (double-blinded) at 7-21 days of age; 29 patients (mean birth weight, 839 g) received "high" dose dexamethasone (0.5 mg/kg/day for 3 days, 0.25 mg/kg/day for 3 days, and 0.1 mg/kg/day on day 7, total dose of 2.35 mg/kg), and 33 infants (mean birth weight, 830 g) received "low-dose" dexamethasone (0.2 mg/kg/day for 3 days and 0.1 mg/kg/day for 4 days, total dose of 1 mg/kg). FRC and Crs were measured with the nitrogen washout technique and single breath occlusion technique, before and on days 2, 5, and 7 of therapy. Clinical outcome and early neurodevelopmental follow-up were evaluated. FRC significantly increased in the high-dose (19.3 ml/kg at baseline to 34 ml/kg on day 7; P < 0.001) and low-dose (18.1 ml/kg at baseline to 30.3 ml/kg on day 7; P < 0.001) dexamethasone groups when compared to baseline. There was a significant increase in Crs and a decrease in FiO2 within each group. The improvements in FRC and Crs were comparable between groups, and specific compliances (Crs/FRC) were not different. There were no significant differences in other clinical outcome parameters, including BPD and neurodevelopmental outcome. In conclusion, there are significant increases in FRC during a 7-day course of moderately early dexamethasone in VLBW infants. The lower total dose (1 mg/kg) appears as effective as the higher total dose of dexamethasone (2.35 mg/kg) in increasing FRC. Comparable significant increases in Crs were observed in both groups of infants. Additional long-term follow-up is underway.