Abstract. Surfactant-associated protein (SP-A) was measured in tracheal aspirates of ventilated infants with (n = 51) and without (n = 21) respiratory distress syndrome (RDS). SP-A concentrations in samples collected after birth were significantly lower in RDS than in infants ventilated for other reasons than RDS (median 0.03 vs. 1.60 gg/ml). As a biochemical test to diagnose RDS early after birth, the sensitivity of measuring SP-A in tracheal aspirates was 87% and specificity 81%. SP-A content in tracheal aspirates of infants with RDS was monitored during the first 7 days of life. A significant (P < 0.001) increase within the first 4 days was found in those infants who survived, whereas no such change was found in those infants who died.

ABSTRACT. We investigated factors that may influence PG, phosphatidylglycerol the response to surfactant substitution. Thirty-five very L/S, lecithin/sphingomyelin ratio low birth weight infants with respiratory distress syndrome were treated with Curosurf at 3-12 h of age. From the changes in oxygenation, the therapeutic response was categorized as rapid and sustained, rapid with relapse, or poor. Phospholipids and surfactant protein A were quanThe efficacy of surfactant rescue treatment has been demontified in gastric aspirate samples obtained immediately strated in numerous controlled trials (1). However, the response after birth. They showed that 16 infants had accelerated to surfactant administration can be variable. Fujiwara et al. (2) lung maturity, despite clinical and radiologic signs of res-found that 6% of preterm infants did not respond to surfactant piratory distress syndrome. Ten of them had suffered from treatment; Hallman et al. these 16 infants responded rapidly to surfactant substitu-after an initially favorable response to surfactant replacement tion. Poor response was seen in four infants with connatal was reported by the same authors in varying incidences [ l 1 % infection. Of 19 infants with immature lung profile, 18 (4), 16% (2), and 56% (3)]. The definitions used for relapse and showed a rapid initial response to surfactant substitution. poor response, however, were different, as were the explanations Dynamic compliance of the respiratory system or arterial for their occurrence. The aim of our study was to relate types of blood pressure before substitution, the ultrastructure of response after surfactant substitution in clinically and radiologithe surfactant preparation, or persistence of the ductus cally diagnosed RDS to the biochemical pattern of the infants' arteriosus did not influence the response type, but fraction surfactant at birth and to evaluate other factors that may influof inspired oxygen was higher before surfactant substitu-ence this response. tion in infants with poor response. Prognosis was related to short-term response: Of 17 infants who showed a rapid PATIENTS AND METHODS