Inclusion criteria are premature newborns under the gestational age (GA) of 32 weeks old with RDS, defined as the need of non invasive mechanical ventilation to keep peripheral oxygen saturation (SpO2) >90% and clinical signs of respiratory distress (polypnea, chest retractions, nasal flutter).

Exclusion criteria are non-acceptance of the informed consent, chromosomal abnormalities, complex congenital malformations, signs of congenital septic shock and mechanical ventilation or endotracheal surfactant prior to the lung ultrasound.

The main objective of the study is to determine if a diagnostic of respiratory distress syndrome guided by a lung ultrasound algorithm allow an earlier surfactant therapy (within the first 2 hours of life) comparing to chest X ray Secondary objectives were to assess FiO2 reached before surfactant therapy in patients surfacted according to the lung ultrasound score, the influence of the lung ultrasound algorithm regarding the respiratory evolution, and its differences comparing to the FiO2group. Respiratory evolution was defined as the need of mechanical ventilation, second dose of surfactant, duration of non invasive ventilation, number of days with oxygen requirements, length of stay in the neonatal intensive care unit, evolution to bronchopulmonary dysplasia and their progression to discharge from hospital.

Patients who met the inclusion criteria were randomly assigned to two groups. using the "random" function in MS-Excel XP® program. A total of 6 physicians enrolled participants, all them fully trained for the use of lung ultrasound. The principal investigator assigned participants to interventions, depending on the randomized list.

• Experimental Group 1: The neonatologist-researcher (NR) performed the lung ultrasond at admission during the first hour of life. The neonatologist-assistant (NA) of the baby was not blinded to the result of the lung ultrasound. If the patient had a lung ultrasound score higher than >8 or when FiO2 exceeded 30% patient received surfactant therapy during in the first 72 hours of life . This lung ultrasound threshold is the one with best diagnostic accuracy.
• Control Group 2: The NR performed the at admission/suspicion during the first hour of life. The NA was not blinded to the result of the ultrasound. Patient received surfactant therapy only when FiO2 exceeded 30% during the first 72 hours of life

Inclusion criteria are premature newborns under the gestational age (GA) of 32 weeks old with RDS, defined as the need of non invasive mechanical ventilation to keep peripheral oxygen saturation (SpO2) >90% and clinical signs of respiratory distress (polypnea, chest retractions, nasal flutter).

Exclusion criteria are non-acceptance of the informed consent, chromosomal abnormalities, complex congenital malformations, signs of congenital septic shock and mechanical ventilation or endotracheal surfactant prior to the lung ultrasound.

The main objective of the study is to determine if a diagnostic of respiratory distress syndrome guided by a lung ultrasound algorithm allow an earlier surfactant therapy (within the first 2 hours of life) comparing to chest X ray Secondary objectives were to assess FiO2 reached before surfactant therapy in patients surfacted according to the lung ultrasound score, the influence of the lung ultrasound algorithm regarding the respiratory evolution, and its differences comparing to the FiO2group. Respiratory evolution was defined as the need of mechanical ventilation, second dose of surfactant, duration of non invasive ventilation, number of days with oxygen requirements, length of stay in the neonatal intensive care unit, evolution to bronchopulmonary dysplasia and their progression to discharge from hospital.

Patients who met the inclusion criteria were randomly assigned to two groups. using the "random" function in MS-Excel XP® program. A total of 6 physicians enrolled participants, all them fully trained for the use of lung ultrasound. The principal investigator assigned participants to interventions, depending on the randomized list.

• Experimental Group 1: The neonatologist-researcher (NR) performed the lung ultrasond at admission during the first hour of life. The neonatologist-assistant (NA) of the baby was not blinded to the result of the lung ultrasound. If the patient had a lung ultrasound score higher than >8 or when FiO2 exceeded 30% patient received surfactant therapy during in the first 72 hours of life . This lung ultrasound threshold is the one with best diagnostic accuracy.
• Control Group 2: The NR performed the at admission/suspicion during the first hour of life. The NA was not blinded to the result of the ultrasound. Patient received surfactant therapy only when FiO2 exceeded 30% during the first 72 hours of life

Inclusion Criteria:

• premature newborns under the gestational age (GA) of 32 weeks old with respiratory distress syndrome

Exclusion Criteria:

• non-acceptance of the informed consent, chromosomal abnormalities, complex congenital malformations, signs of congenital septic shock and mechanical ventilation or endotracheal surfactant prior to the ultrasoundLUS