Am. J. Respir. Crit. Care Med., Vol 151, No. 1, Jan 1995, 21-26.
Fetal corticosteroid and T4 treatment effects on lung function of surfactant-treated preterm lambs
CM Chen, M Ikegami, T Ueda, DH Polk and AH Jobe
Department of Pediatrics, Harbor-UCLA Medical Center, UCLA School of Medicine.
Three groups of sheep fetuses at 125 or 126 d gestational age randomly
received a single ultrasound-guided intramuscular injection of saline, 0.5
mg/kg betamethasone, or 0.5 mg/kg betamethasone plus 50 micrograms/kg
thyroxine (T4). Forty-eight hours later the fetuses were delivered, treated
with a pulmonary surfactant preparation, and ventilated for 3 h.
Corticosteroids alone and in combination with T4 increased FRC, compliance,
and lung volumes, and decreased the protein leak into the airspace.
Saturated phosphatidylcholine pool sizes recovered by alveolar washing were
not changed after hormone treatment. To evaluate the function of surfactant
recovered from the lambs in vivo, we treated preterm rabbits at 27 d
gestational age with the large- aggregate surfactant from alveolar washes.
Large-aggregate surfactants and the pulmonary surfactant preparation
increased compliances and maximal lung volumes relative to those in
untreated preterm rabbits. Large-aggregate surfactants improved compliance
more than did the pulmonary surfactant preparation. We conclude that
ultrasound-guided single fetal corticosteroid treatment followed by
postnatal surfactant improved postnatal lung function in preterm lambs.
Addition of T4 did not augment corticosteroid effects. The function of the
exogenous surfactant was improved in premature lamb lungs independently of
the fetal treatment modality.
