The purpose of the present study was to examine the pattern of changes in respiratory system mechanics induced by
dexamethasone (Dex) in infants with
bronchopulmonary dysplasia (BPD) and to determine whether dosages that produce these changes induce adrenal suppression. We examined mechanics in seven
ventilator-dependent premature infants (age, 33 +/- 4.8 days) with BPD, before and daily during Dex
therapy. Dex (0.5 mg/kg/day) was given intravenously for 7 days unless complications necessitated early termination. Respiratory system resistance (Rrs) and compliance (Crs) were measured by the passive expiratory flow-volume technique during the course of
dexamethasone therapy or until extubation.
Adrenocorticotrophic hormone (
ACTH) stimulation tests were done at baseline and following Dex
therapy to evaluate adrenal function. Dex
therapy caused a 77 +/- 18% increase in Crs (from 0.97 +/- 0.09 SEM mL/cmH2O to 1.6 +/- 0.16 mL/cmH2O; P less than 0.025) and a 33 +/- 5% decrease in Rrs (from 0.20 +/- 0.02 cmH2O/mL/s to 0.14 +/- 0.01 cmH2O/mL/s; P less than 0.01). Concurrently,
ventilator rate, mean airway pressure, and FIO2 all decreased significantly (P less than 0.025). Extubation occurred later in infants with the lowest Crs and highest Rrs at baseline. At extubation, all Crs values were greater than 1.33 mL/cmH2O and Rrs values were less than 0.15 cmH2O/mL/s. Systolic blood pressure increased from 61 +/- 6.3 mmHg to 84 +/- 17 mmHg, 72-96 h after the start of Dex (P less than 0.025). There were no episodes of culture-positive
sepsis. Neither basal nor
ACTH-stimulated levels of
cortisol were suppressed as a result of Dex
therapy (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)