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Minimum interval from fetal betamethasone treatment to postnatal lung responses in preterm lambs
1Department of Pediatrics, Harbor-University of California, Los Angeles, Medical Center 90509, USA.
Objective:
We hypothesized that fetal betamethasone exposure for < 24 hours would improve postnatal lung function in preterm lambs.
Study Design:
Singleton fetal sheep were randomized to receive by ultrasonographically guided fetal injections of 0.5 mg/kg betamethasone or saline solution either 8 or 15 hours before preterm delivery and postnatal assessment of lung function.
Results:
After the 15-hour fetal treatment-to-delivery interval, betamethasone-treated lambs had twofold improvement in compliance and lung volumes, a fourfold to fivefold decrease in edema index, and higher blood pressures than saline solution-treated lambs. Postnatal lung function or lung volumes did not improve for the 8-hour treatment-to-delivery interval, although betamethasone decreased the pulmonary edema and increased the postnatal blood pressure.
Conclusions:
The minimal interval from fetal exposure to corticosteroids to delivery for improved postnatal lung function was between 8 and 15 hours. Corticosteroid effects on pulmonary edema and blood pressure occurred within 8 hours.