Related to safety. Adverse Events (AE). Measuring time: An hour after first dose until 28 days. - Type of AE (Name of event) - Time to occurrence of AE (hours, minutes or days, between product administration and the occurrence of AE) - Duration of the AE (hours, minutes or day that is present the AE) - Severity/Seriousness of the AE (Serious, Not serious) - Intensity of the AE (Mild, Moderate, Severe) - Causality relationship (Definitive, Very likely, Likely, Possible, Unrelated, Unknown) - Attitude (Without change, Temporary stop, Permanent stop) - Treatment of the AE (Treatment for the AE). - Result of the AE (Reversible effect, Irreversible effect, Death, or Loss to follow-up the patient). - Lot of SURFACEN® (batch number of the product) Related to effectiveness Changes in PaO2/FiO2 (value provided by the Blood gas analyzer of Intensive Care Unit-ICU). Measuring time: at baseline, an hour after each dose. pH (Value provided by the Blood gas analyzer of ICU). Measuring time: at baseline, an hour after each dose. DA-aO2 (value calculated from the formula [Fi O2 (PB-PH 2 O) -PaCO2] -PaO2 where PB = 760mmHg, PH 2 O = 47mmHg, taking into account normal PaCO2 references (35-48 mmHg (4.7 - 6.4 kPa) men 32-45 mmHg (4.3 - 6.0 kPa) women), PaO2 83-108 mmHg and pH 7.35-7.45). Measuring time: at baseline, an hour after each dose. Ventilatory mode (pressure, volume). Measuring time: at baseline, an hour after each dose. Tidal volume (Vt L / min given by the ventilator available in the ICU). Measuring time: at baseline, an hour after each dose. Respiratory Rate (RR in minutes (min), given by the ventilator in the ICU). Measuring time: at baseline, an hour after each dose. Peak pressure (Pr cmH2O peak given by the ventilator in the ICU). Measuring time: at baseline, an hour after each dose. Airway Plateau Pressure (PPlat in cmH2O given by the ventilator in the ICU). Measuring time: at baseline, an hour after each dose. Relationship inspiration / expiration (I / E, given by the ventilator in the ICU setting). Measuring time: at baseline, an hour after each dose. PEEP (value in cmH2O given by the ventilator in the ICU, considering ranges 6-10, 11-15, 16-20, over 20). Measuring time: at baseline, an hour after each dose. Static lung compliance (Cs, calculated from Vt/(Pplat-PEEP) value). Measuring time: at baseline, an hour after each dose. Alveolar recruitment maneuver (Yes, No). Measuring time: at baseline, an hour after each dose. Duration of mechanical ventilation (days and hours, from the difference between the dates and times of beginning and end of mechanical ventilation). Measuring time: at baseline, an hour after each dose. Mechanical ventilation time (days and hours, from the difference between ICU stay and duration of mechanical ventilation) ventilation. Measuring time: at baseline, an hour after each dose. Blood pressure (BP, value of systolic and diastolic in mmHg). Measuring time: at baseline, an hour after each dose. Heart rate (HR, min value). Measuring time: at baseline, an hour after each dose. Central venous pressure (CVP, value cmH2O). Measuring time: at baseline, an hour after each dose. Temperature (T, value in Celsius grade). Measuring time: at baseline, an hour after each dose. Cyanosis (Absence, distal cyanosis, generalized cyanosis). Measuring time: at baseline, an hour after each dose. Inflammatory infiltrates in the lung fields (Improvement, Stabilization, Worsening). Measuring time: at baseline, at 24, 48, 72, 96 and 120 hours of starting treatment. Time in the ICU (Days and hours from the difference between the dates and times of entry and exit of the ICU patient). Measuring time: at discharge from the ICU. Patient status at the egress from the ICU (Alive, Death). Measuring time: at discharge from the ICU. Patient status at 28 days (Alive, Death). Measuring time: 28 days. Diagnostic Survival (Difference in days between the diagnosis of ARDS date and death of the patient, when the patient dies). Measuring time: 28 days. Inclusion Survival (Difference in days between the starting treatment date and death of the patient, when the patient dies). Measuring time: 28 days.