Effects of fetal corticosteroid treatments on postnatal surfactant
function in preterm lambs.
Ueda, Takashi, Machiko Ikegami, Daniel Polk, Katsumi Mizuno, Alan
Jobe.
Department of Pediatrics, Harbor-UCLA Medical Center, UCLA School
of Medicine, Torrance, CA, 90509
APStracts 2:0227A, 1995.
Effects of prenatal corticosteroid on the properties of surfactant
have not previously been evaluated. A single ultrasound-guided fetal
injection with 0.5 mg/kg betamethasone 48 h prior to delivery of
preterm lambs at 134-5 d gestation improved oxygenation, lowered the
ventilatory pressures required to maintain PaCO2 between 30-40 mmHg,
and decreased the protein leak of albumin from the intravascular to
the alveolar space. This dose of glucocorticoid did not alter
surfactant saturated phosphatidylcholine pool sizes in the airspaces
of preterm lambs. However, the treatment changed the characteristics
of the surfactant recovered from the ventilated preterm lambs. The in
vitro conversion from heavy to light subtype surfactant decreased
from 59% for the saline treated lambs to 37% for the corticosteroid
treated lambs following 180 min of surface area cycling (p<0.02).
Surfactant from the corticosteroid treated lambs also increased the
dynamic compliance of preterm surfactant deficient rabbits more than
did surfactant from the saline treated lambs (p<0.05). Prenatal
treatment of preterm lambs with betamethasone improved the functional
characteristics of surfactant without significant effects on the
alveolar surfactant pool sizes.
Received 28 April 1994; accepted in final form 24 April 1995.
APS Manuscript Number A392-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 May 1995.