A soluble form of thrombomodulin (TM), an anticoagulant proteoglycan of the endothelial cell membrane, considered a marker of vascular endothelial damage, was measured in plasma of preterm infants with respiratory distress syndrome (RDS). In these patients, lung immaturity leads to endothelial leak of plasma proteins and to surfactant inhibition. In 18 babies with RDS, plasma TM concentration was significantly elevated compared with values of a matched group of babies without pulmonary disease (276.1 ng/ml vs 141.3 ng/ml) (P < 0.05). Furthermore, TM levels of mechanical ventilated babies (IPPV) with severe RDS were higher than those of babies with moderate RDS and treated with nasal CPAP (340.9 ng/ml vs 174.2 ng/ml) (P < 0.05).
Conclusion: These data show that TM can be used as marker of pulmonary endothelial damage in preterm babies treated with mechanical ventilation for RDS and suggest early intervention with exogenous surfactant to limit alveolar protein leakage and surfactant inactivation.