inclusion criteria: * o2 saturation \<93% * radiographic evidence of moderate pneumonia according to rale's classification. * acute respiratory distress syndrome (pao2 / fio2 \<300 or spo2 / fio2 ≤ 315) * authorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)

inclusion criteria: * o2 saturation \<93% * radiographic evidence of moderate pneumonia according to rale's classification. * acute respiratory distress syndrome (pao2 / fio2 \<300 or spo2 / fio2 ≤ 315) * authorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)

inclusion criteria: - o2 saturation <93% - radiographic evidence of moderate pneumonia according to rale's classification. - acute respiratory distress syndrome (pao2 / fio2 <300 or spo2 / fio2 ≤ 315) - authorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)

inclusion criteria: - o2 saturation <93% - radiographic evidence of moderate pneumonia according to rale's classification. - acute respiratory distress syndrome (pao2 / fio2 <300 or spo2 / fio2 ≤ 315) - authorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)

inclusion criteria: - o2 saturation <93% - radiographic evidence of moderate pneumonia according to rale's classification. - acute respiratory distress syndrome (pao2 / fio2 <300 or spo2 / fio2 ≤ 315) - autorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)

inclusion criteria: - o2 saturation <93% - radiographic evidence of moderate pneumonia according to rale's classification. - acute respiratory distress syndrome (pao2 / fio2 <300 or spo2 / fio2 ≤ 315) - autorization to participate in the study and have informed consent letter, signed by the patient or the person responsible for the patient in case of critical patients (intubated)