Pulmonary prostacyclin is associated with less severe respiratory distress in preterm infants.

BACKGROUND

Prostacyclin (PGI(2)) and thromboxane A(2) (TxA(2)) may take part in lung pathology; high concentrations of PGI(2) may protect newborn rabbits against hyperoxic lung injury, and TxA(2) may participate in the development of bronchopulmonary dysplasia (BPD).

AIMS: To examine in small preterm infants, the relationship between pulmonary PGI(2) and TxA(2) and respiratory distress during the early postnatal period.

METHODS

The stable metabolite of prostacyclin, 6-keto-prostaglandinF(1 alpha), and that of thromboxane A(2), thromboxane B(2), were quantified by radioimmunoassays in 284 samples of tracheal aspirates from 48 infants (GA: 27.4+/-2.1 week, BW 959+/-334 g) during the first 12 postnatal days.

RESULTS

Mean concentration of 6-keto-prostaglandinF(1 alpha) was 414+/-31 pg/ml (mean+/-S.E.M.), and of thromboxane B(2) was 418+/-37 pg/ml. Correlations existed between 6-keto-prostaglandinF(1 alpha) and gestational age, birth weight, and the initial arterial-alveolar oxygenation ratio. Negative correlations existed between 6-keto-prostaglandinF(1 alpha) and both mean inspiratory oxygen and duration of mechanical ventilation. Indomethacin treatment was associated with lower pulmonary 6-keto-prostaglandinF(1 alpha), but not with lower TxB(2). Thromboxane B(2) correlated positively with gestational age, birth weight, and initial arterial-alveolar oxygenation ratio, and inversely with duration of mechanical ventilation.

CONCLUSIONS

In preterm infants, higher pulmonary 6-keto-prostaglandinF(1 alpha) was associated with less severe respiratory distress and with maturity, whereas thromboxane B(2) was associated more strongly with maturity than with respiratory distress.