AIM: The aim of the present study was to determine immediate changes of global and regional lung function after exogenous surfactant administration in mechanically ventilated infants with respiratory distress syndrome (RDS) using electrical impedance tomography (EIT) measurements.MATERIALS AND METHODS: A prospective study was conducted in a Neonatal Intensive Care Unit at a university hospital. Seventeen preterm infants (<12 hours old) suffering from RDS were included in this study. Interventions taken were low-pressure recruitment maneuver, surfactant administration and minimal adjustments in ventilator settings. Repeated EIT measurements (401 in total) were performed before and after (15 min - 30 min) surfactant administration. Global lung function changes were assessed with two markers, namely absolute resistivity (AbsR) and normalized impedance change (ΔZ); redistribution of regional lung ventilation was assessed as well. Airway pressure and arterial blood gases were recorded.RESULTS: Surfactant administration resulted in a statistically significant increase of both the AbsR and ΔZ markers. Moreover, there was a ventilation shift towards dorsal - dependent lung areas with less asymmetry in the right-to-left air distribution.CONCLUSIONS: Surfactant administration in the recruited lung with RDS modifies regional ventilation, as assessed by EIT, contributing to a more homogeneous air distribution. Furthermore, significant changes in EIT markers reflect improvement of global lung function after surfactant administration.