inclusion criteria: * age 18 years or older; * intubated and mechanically ventilated; * acute onset of ahrf (as defined by a pao2/fio2 ≤300 mmhg during at least 6 hours from diagnosis. for the measurement of pao2 and calculation of pao2/fio2 ratio, the minimum accepted value for peep is 5 cmh2o and for fio2 is 0.3. ards is defined by berlin criteria,4 which includes: (i) having pneumonia or worsening respiratory symptoms, (ii) bilateral pulmonary infiltrates on chest imaging (x-ray or ct scan), (iii) absence of left atrial hypertension or no clinical signs of left heart failure, and (iv) hypoxemia, as defined by a pao2/fio2 ≤300 mmhg on positive end-expiratory pressure (peep) of ≥5 cmh2o, regardless of fio2. * pulmonary or systemic infectious etiology of ahrf.

inclusion criteria: * age 18 years or older; * intubated and mechanically ventilated; * acute onset of ahrf (as defined by a pao2/fio2 ≤300 mmhg during at least 6 hours from diagnosis. for the measurement of pao2 and calculation of pao2/fio2 ratio, the minimum accepted value for peep is 5 cmh2o and for fio2 is 0.3. ards is defined by berlin criteria,4 which includes: (i) having pneumonia or worsening respiratory symptoms, (ii) bilateral pulmonary infiltrates on chest imaging (x-ray or ct scan), (iii) absence of left atrial hypertension or no clinical signs of left heart failure, and (iv) hypoxemia, as defined by a pao2/fio2 ≤300 mmhg on positive end-expiratory pressure (peep) of ≥5 cmh2o, regardless of fio2. * pulmonary or systemic infectious etiology of ahrf.

inclusion criteria: - age 18 years or older; - intubated and mechanically ventilated; - acute onset of ahrf (as defined by a pao2/fio2 ≤300 mmhg during at least 6 hours from diagnosis. for the measurement of pao2 and calculation of pao2/fio2 ratio, the minimum accepted value for peep is 5 cmh2o and for fio2 is 0.3. ards is defined by berlin criteria,4 which includes: (i) having pneumonia or worsening respiratory symptoms, (ii) bilateral pulmonary infiltrates on chest imaging (x-ray or ct scan), (iii) absence of left atrial hypertension or no clinical signs of left heart failure, and (iv) hypoxemia, as defined by a pao2/fio2 ≤300 mmhg on positive end-expiratory pressure (peep) of ≥5 cmh2o, regardless of fio2. - pulmonary or systemic infectious etiology of ahrf.

inclusion criteria: - age 18 years or older; - intubated and mechanically ventilated; - acute onset of ahrf (as defined by a pao2/fio2 ≤300 mmhg during at least 6 hours from diagnosis. for the measurement of pao2 and calculation of pao2/fio2 ratio, the minimum accepted value for peep is 5 cmh2o and for fio2 is 0.3. ards is defined by berlin criteria,4 which includes: (i) having pneumonia or worsening respiratory symptoms, (ii) bilateral pulmonary infiltrates on chest imaging (x-ray or ct scan), (iii) absence of left atrial hypertension or no clinical signs of left heart failure, and (iv) hypoxemia, as defined by a pao2/fio2 ≤300 mmhg on positive end-expiratory pressure (peep) of ≥5 cmh2o, regardless of fio2. - pulmonary or systemic infectious etiology of ahrf.