Pulmonary function and outcomes in infants randomized to a rescue course of antenatal steroids

Abstract

Background/objective: Our objective was to obtain follow-up pulmonary function testing and assessment of clinical respiratory outcomes, at 1-2 years, in preterm infants whose mothers were randomized to a single rescue course of antenatal steroids (AS) versus placebo.

Methods: Follow-up of a randomized, double-blinded trial. In the original trial pregnant women ≥14 days after initial course of AS were randomized to rescue AS or placebo. Pulmonary function testing and a standardized respiratory questionnaire were obtained at 1-2 years of corrected age. Respiratory compliance (Crs) was measured with the single-breath occlusion and functional residual capacity (FRC) with the nitrogen washout method. Analysis was by intention-to-treat.

Results: A total of 96 (87%) of available survivors were administered a respiratory questionnaire. Seventy-seven percent of available patients had pulmonary function testing performed. There was no significant difference between groups in incidence of wheezing, asthma, respiratory syncytial virus infection, respiratory readmissions, use of bronchodilators or other medications, or in measurements of pulmonary function. There was also no significant difference in corrected age at study, race, gender, or length at the time of pulmonary function testing. Infants in the rescue group had a comparable mean FRC (249.4 mL vs 246.2 mL; adjusted 95%CI for difference -15.45, 38.20; P = 0.37) versus placebo. There were no differences in tidal volume or Crs.

Conclusion: A rescue course of AS significantly increases Crs within 72 h of age and decreases oxygen need in newborn infants, without an adverse impact on pulmonary function or clinical respiratory outcomes at 1-2 years of age [NCT00669383].

Keywords: betamethasone; clinical respiratory outcomes; functional residual capacity; infant pulmonary function; rescue antenatal corticosteroids; respiratory compliance; tidal volume.

© 2017 Wiley Periodicals, Inc.

Figures

Figure 1

Outline of randomization, treatment, and follow-up of study participants. A few patients in the rescue AS group and in the placebo group did not have PFT measurements because parents refused sedation or due to inability to meet the acceptance testing criteria., Abbreviations: AS, antenatal steroids; PFTs, pulmonary function tests; SHH, Sacred Heart Hospital.

Figure 2

Total FRC (mL) plotted against length (cm) at time of pulmonary function testing. Individual data in the cohort of infants randomized to rescue antenatal steroids (open circles) versus placebo (solid triangles) are presented. There was no significant difference in total FRC when both groups were compared when adjusted for body length at PFT, corrected age at PFT, and family history of asthma by mixed linear modeling (P = 0.37). Abbreviations: FRC, functional residual capacity; PFT, pulmonary function test.