Postnatal lung function in lambs after fetal hormone treatment. Effects of gestational age.
We previously found that a single dose of betamethasone in combination with thyroxine given by intramuscular injection to fetal sheep 48 h before preterm delivery at 128 d gestation improved postnatal lung function. We have now asked how the combination of 0.5 mg/kg betamethasone and 15 micrograms/kg T4 given by a single fetal intramuscular injection changes lung response 48 h after treatment at 121 and 135 d gestation. At 121 d gestation the fetal hormone treatment significantly improved postnatal lung function. Compliance increased by 55%, arterial PO2 increased from 39 to 215 mm Hg, PCO2 decreased from 109 to 79 mm Hg, and maximal lung volumes increased by 112%. The hormone treatment decreased the severity of the respiratory failure, although these very preterm lambs still had severe respiratory failure. At 135 d gestation, the fetal hormone treatment decreased the ventilatory pressure requirements that were needed to normalize PCO2 values from 30 to 21 cm H2O. Compliance increased by 40%, and maximal lung volumes increased by 33%. Alveolar or lung tissue, saturated phosphatidylcholine, or alveolar SP-A pool sizes did not change with hormone treatment at 135 d gestation. We conclude that fetal hormone treatment significantly improved postnatal lung function at both gestational ages, although the characteristics of the responses were different.
Ikegami
M
M
Department of Pediatrics, Harbor-UCLA Medical Center, Torrance 90509, USA.
Polk
D H
DH
Jobe
A H
AH
Newnham
J
J
Sly
P
P
Kohen
R
R
Kelly
R
R
D000818:Animals; D000831:Animals, Newborn; D001623:Betamethasone / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D005865:Gestational Age; D005938:Glucocorticoids / Q000627:therapeutic use*; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*; D012756:Sheep; D013974:Thyroxine / Q000627:therapeutic use*
D005938:Glucocorticoids; D001623:Betamethasone; D013974:Thyroxine