Mimicking low amniotic pressure by chronic pharyngeal drainage does not impair lung development in fetal sheep.
OBJECTIVE
The etiology of oligohydramnios-related pulmonary hypoplasia is not understood but is known to involve chronic lung liquid loss. We tested the hypothesis that low amniotic pressure in oligohydramnios disturbs the normal tracheal-amniotic pressure gradient to increase lung liquid loss and impair lung development.


METHODS
Chronic pharyngeal catheterization with drainage to the exterior was used in 15 fetal sheep to mimic reduced amniotic pressure at the upper airway in the presence of normal amniotic fluid volume.


RESULTS
Pharyngeal pressures relative to amniotic pressures were negative in all drained fetuses (mean +/- SE -3.0 +/- 0.6 mm Hg), in contrast to positive pressures in controls (0.7 +/- 0.1 mm Hg). There was no significant difference in lung weight or deoxyribonucleic acid relative to body weight, or in lung morphometry, between 10 fetuses drained for 10 to 21 days and their control cotwins.


CONCLUSIONS
Mimicking low amniotic pressure in the upper airway by chronic fetal pharyngeal drainage does not impair lung development in fetal sheep.
Fisk
N M
NM
Department of Physiology and Biochemistry, University of Reading.
Parkes
M J
MJ
Moore
P J
PJ
Hanson
M A
MA
Wigglesworth
J
J
Rodeck
C H
CH
D000653:Amniotic Fluid / Q000502:physiology*; D000818:Animals; D001835:Body Weight; D004247:DNA / Q000378:metabolism; D005314:Embryonic and Fetal Development; D008168:Lung / Q000196:embryology* / Q000378:metabolism; D010614:Pharynx / Q000196:embryology*; D011312:Pressure; D012756:Sheep / Q000196:embryology; D013396:Suction; D013997:Time Factors
D004247:DNA