Background and Aim Whether pulmonary surfactant deficiency or dysfunction contributes to the pathogenesis of neonatal pneumonia is still debated. Aim of our study was to measure surfactant disaturated-phosphatidylcholine (DSPC) kinetics and surfactant specific proteins A and B (SP-A, SP-B) amount in term newborns with pneumonia using stable isotopes as tracers.

Methods Twenty-seven term newborns (GA 39.0±1.5 weeks, BW 3165±602 g) requiring mechanical ventilation were studied. Twelve had severe pneumonia and 15 no lung disease. All newborns received intra-tracheally 2 mg/kg U¹³C-DPPC mixed with 2 mg/kg of exogenous surfactant. Isotopic enrichment of DSPC palmitate was measured from tracheal aspirates by mass spectrometry and kinetic data calculated. Surfactant proteins were measured by ELISA. Data were expressed as median (interquartile range) and comparisons were performed by Mann-Whitney test. p<0.05 was regarded as statistically significant.

Results DSPC pool size (PS) was 9.3 mg/kg (3.1–30.2) in newborns with pneumonia and 38.0 mg/kg (24.9–124.6) in controls, p=0.016. DSPC half-life (HL) was 12.7 h (5.2–20.2) and 25.6 h (18.5–65.6) in newborns with pneumonia and in controls, respectively (p=0.004). Analysis for SP-A and SP-B are in progress. In newborns with pneumonia a correlation was found between DSPC kinetic parameters and oxygen requirement (DSPC PS and mean FiO2, R= –0.61, p=0.047; DSPC HL and mean FiO2, R= –0.54, p=0.086).

Conclusions Surfactant DSPC kinetics was found to be markedly impaired in term newborns with pneumonia. Preliminary data suggest that these alterations correlate with disease severity; thus, studies on exogenous surfactant therapy and on the effect on surfactant metabolism are needed.