Comparing the efficacy of intravenous Dexamethasone and Inhaler N-Acetyl Cysteine plus intravenous Dexamethasone in treatment of Respiratory Distress Syndrome

INTERVENTION: ?First group will undergo treatment with Intravenous Dexamethasone 0.15 mg/kg every 12 hours for 3 to 5 days Intervention 1: ?First group will undergo treatment with Intravenous Dexamethasone 0.15 mg/kg every 12 hours for 3 to 5 days. Intervention 2: The second group will undergo treatment with inhaler N‐Acetyl Cysteine through jet nebulizer (400 mg every 8 hours) for 3 to 5 days. The second group will undergo treatment with inhaler N‐Acetyl Cysteine through jet nebulizer (400 mg every 8 hours) for 3 to 5 days. Treatment ‐ Drugs CONDITION: Respiratory distress syndrome of newborn Respiratory distress syndrome of newborn. ; Respiratory distress syndrome of newborn PRIMARY OUTCOME: Blood Pressure. Timepoint: before and after extubation. Method of measurement: Monitring System. Oxygen Saturation. Timepoint: before and after extubation. Method of measurement: Pulse Oxymetry. PH. Timepoint: before and after extubation. Method of measurement: Arterial Blood Gas Assessment. Respiratory rate. Timepoint: before and after extubation. Method of measurement: one minute counting by nurse. INCLUSION CRITERIA: INCLUSION CRITERIA: birth weight between 1000‐2500 gr;Gestational age of less than 36 weeks;Mechanical ventilation for at least two days;Oxygen saturation of more than 30% after extubation;PH<7.2;PCO2>55;PaO2<50 Exclusion Criteria:Hemorrhagic lesions;Congenital Anomalies;Chromosomal Anomalies;early sepsis;death before 72 hours of age