Minimum interval from fetal betamethasone treatment to postnatal lung responses in preterm lambs.
OBJECTIVE
We hypothesized that fetal betamethasone exposure for < 24 hours would improve postnatal lung function in preterm lambs.


METHODS
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.
Ikegami
M
M
Department of Pediatrics, Harbor-University of California, Los Angeles, Medical Center 90509, USA.
Polk
D
D
Jobe
A
A
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001623:Betamethasone / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D005325:Fetal Organ Maturity / Q000187:drug effects; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D008168:Lung / Q000187:drug effects* / Q000196:embryology / Q000502:physiology; D008176:Lung Volume Measurements; D008297:Male; D011312:Pressure; D012709:Serum Albumin / Q000493:pharmacokinetics; D012756:Sheep / Q000196:embryology; D013997:Time Factors
D012709:Serum Albumin; D001623:Betamethasone