1205 LUNG MATURITY AND THE PATENT DUCTUS ARTERIOSUS: WHY VENTILATE THE PDA?

Abstract

Alterations in tracheal aspirate phospholipids (TAPL) during recovery from respiratory distress syndrome (RDS) previously have been defined (Ped. Res. 10:984, 1976), the appearance of phosphatidylglycerol (PGL) on day 5 indicating lung maturity. In 11 preterm infants (B.W. 1302±357 gm; G.A. 30.6±2 wks) with sequential TAPL, 6 infants followed a characteristic maturational time course while in 5 infants PGL appeared on day 2 indicating “early” lung maturity. In these 5 infants hemodynamically significant PDA (bounding pulses, murmur, hyperactive precordium; LA/Ao ≥.9 pulmonary plethora) occurred at 2.2±.4 days compared to 2.4±3 days in infants showing lung maturation on day 5. Both groups had similar oxygen requirements & duration of ventilation (93.8 hr. vs 118.8 hr.) to maintain Pao₂ ≥50 torr & acid-base equilibrium inspite of biochemical evidence of lung maturity in the former. Evidence of pulmonary maturation in infants with pulmonary hyperperfusion due to a large left-to-right ductal shunt suggests that continued & increasing ventilatory requirements are due to ductal shunting rather than surfactant deficiency. Sequential TAPL in infants with RDS offers a basis for predicting ventilatory requirements during the course of RDS whereby maturing TAPL may suggest the timing for ductal closure; this deteriorating pulmonary function is owing to pulmonary edema rather than immature surfactant. Supported by HD-05292; HD-04380

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