111 Surfactant Proteins in Prematurity in Relation to Perinatal Complications

Abstract

Background: The outcome of premature infants is mainly determined by lung function in the first days of life. The pulmonary surfactant (SF) system plays a major role in maintaining lung function and is strongly impaired in the premature lung. We aimed to investigate surfactant protein (SP) levels in tracheal aspirates (TA) of preterm infants and their relation to perinatal complications.Methods: 45 intubated and mechanically ventilated preterm infants (median 27, range 23–31 weeks gestational age; GA), all suffering from respiratory distress syndrome (RDS), were prospectively included in the study. TA were obtained in the first 12 hours of life before SF treatment following a standardized study protocol, SP-A, B, C and D concentrations were determined by means of ELISA techniques and normalized to the phospholipid (PL) concentration of each sample. Clinical variables were monitored. 12 pulmonary healthy infants (0–4 months of age), intubated before elective surgery, served as control group. Mann-Whitney U test was performed for statistical analysis.Results: Levels of SP-C (0.53; 0.11–5.82 % (w/w) SP-C/PL) and SP-D (0.0011; 0.0002–0.0207 % (w/w) SP-D/PL) were significantly reduced in preterm infants < 32 weeks GA compared to controls (1.80; 0.38–6.06 % SP-C/PL, p< 0.01; 0.0118; 0.0029–0.0233 % SP-D/PL, p< 0.005; median and range each). In contrast, SP-B concentrations were significantly elevated in preterms (0.41; 0.14–1.74 % (w/w) SP-B/PL) compared to controls (0.20; 0.15–0.45 % (w/w) SP-B/PL, p< 0.005), whereas SP-A was not significantly different between the groups. SP-C concentrations were significantly elevated in the group of preterms delivered by c-section with contractions (0.62; 0.47–0.86 vs 0.46; 0.11–2.18 % (w/w) SPC/PL; p< 0.04). Furthermore, SP-B and -D levels were significantly increased in preterm infants when clinically relevant haemorrhage was apparent under birth (p< 0.002).Conclusion: This is the first report describing levels of all four SP in tracheal aspirates in a well defined group of preterm infants. It was shown that SP are differentially regulated in preterm infants and are depending on perinatal complications.