Failure of acute perinatal asphyxia or meconium aspiration to produce persistent pulmonary hypertension in a neonatal baboon model.
OBJECTIVE
Our purpose was to determine whether perinatal asphyxia or meconium aspiration, or both, can produce the physiologic and histologic pulmonary vascular changes associated with the meconium aspiration syndrome.


METHODS
Twenty neonatal baboons were studied in four groups: 1, control; 2, meconium aspiration; 3, asphyxia (intermittent cord compression); and 4, asphyxia with meconium aspiration. Animals were ventilated for 24 hours under ketamine, diazepam, and pancuronium. Data were analyzed by means of mixed model analysis of measures.


RESULTS
Meconium significantly impaired oxygenation (p < 0.001), whereas concurrent asphyxia moderated this effect (p < 0.034). Meconium also increased the need for ventilatory support (p < 0.002). No animal had persistent pulmonary hypertension; neither systemic nor pulmonary systolic pressures differed statistically between the groups. No animal showed evidence of abnormal pulmonary arteriolar muscularization.


CONCLUSIONS
Sublethal perinatal asphyxia or meconium aspiration were insufficient to produce either the physiologic or histologic changes of severe meconium aspiration syndrome. It is unlikely that intrapartum fetal distress alone can produce this syndrome in human neonates.
Department of Pediatrics, Wilford Hall United States Air Force Medical Center, San Antonio, Texas.
J D
JD
Cornish
G L
GL
Dreyer
G E
GE
Snyder
T J
TJ
Kuehl
D R
DR
Gerstmann
D M
DM
Null
J J
JJ
Coalson
R A
RA
deLemos
D000208:Acute Disease; D000818:Animals; D000831:Animals, Newborn; D001238:Asphyxia Neonatorum / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D005316:Fetal Distress / Q000150:complications; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000473:pathology; D008471:Meconium Aspiration Syndrome / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D010215:Papio; D010547:Persistent Fetal Circulation Syndrome / Q000209:etiology*