Abstract
A potential side effect of exogeneous surfactant is inhibition of the endogeneous surfactant secretion. We have studied this question. Human surfactant (HS, 120 mg/kg) was given before the age of 10 h, in order to treat severe RDS. Tracheal aspirates (N=128) were recovered from ten infants (BW 1013±285 g; GA '27.4±1.1 w; 5 received HS, 5 controls) and analyzed for phospholipids. The interpretation of the results is based upon the following knowledge: 1. In tracheal aspirate the phospholipid composition is similar to that in alveolar lavage. 2. Surfactant phospholipids from RDS and from no-RDS are similar except for the acidic phospholipids: in RDS there is only phosphatidylinositol (PI), whereas normal surfactant contains both PI and phosphatidylglycerol (PG). 3. The high serum myoinositol in RDS prevents PG synthesis (J.Clin.Invest. 68, 742,1981).
The turnover of exogeneous HS was measured on the basis of the exponential decay data of PG/(PG+PI)-ratio. The half-life of PG was 33±5 h. HS substitution increased HS pool size 5-22-fold, and increased saturated lecithin/sphingomyelin (L/S) from 3.0±0.4 to 25.0±8.3. Subsequently L/S remained high and the respiratory status improved. At the age of one week the treated infants had higher L/S than the controls (22.4±3.7 vs 9.4±1.7). According to present evidence exogeneous HS did not suppress endogeneous HS secretion. Instead, exogeneous HS may be utilized for endogeneous synthesis of surfactant.
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Hallman, M., Merritt, T. & Gluck, L. SURFACTANT SUBSTITUTION IN RDS. AN EVALUATION OF THE TURNOVER OF EXOGENEOUS AND ENDOGENEOUS SURFACTANT. Pediatr Res 18, 802 (1984). https://doi.org/10.1203/00006450-198408000-00066
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DOI: https://doi.org/10.1203/00006450-198408000-00066