Surfactant protein B and disaturated phosphatidylcholine levels in Survanta treated premature infants. 1457

Abstract

Premature infants are routinely treated with multiple doses of exogenous surfactant to ameliorate their respiratory distress, but the status of surfactant in such infants has not been determined. This study evaluated disaturated phosphatidylcholine (DSPC) and SP-B levels in tracheal washings of four infants (27 wks gestation) before and after Survanta treatments (arrows). Tracheal washings were obtained by suctioning following instillation of normal saline (0.7 ml) at indicated intervals (Fig.). The pre-treatment levels of SP-B and DSPC in tracheal washings were 1.93 ± 1.22 μg/mg protein and 8.25 ± 3.2 μg phosphorous (Pi)/mg protein, respectively. Two hours after Survanta instillation, the levels for both were higher (4-7 fold) and were unchanged after 10 hours. These results suggest that a single application of Survanta is sufficient to raise the DSPC and SP-B to a steady state and that these two are cleared very slowly. A second dose did not change the SP-B levels. In comparison, the DSPC levels were further increased by ≈50% but later returned to pre-second dose levels. We speculate that excess surfactant protein and lipids may be cleared independently to maintain individual steady state levels.