Respiratory Mechanics Assessment During Assisted Mechanical Ventilation

Inclusion Criteria: * Acute Hypoxaemic Respiratory Failure (defined as respiratory failure requiring invasive mechanical ventilation with a PaO2/FiO2\< 300 mmHg) during the course of ICU stay (including ARDS). * Invasive mechanical ventilation in one of these modes: Pressure A/C, PRVC, SIMV PC, PSV, NAVA, PAV+, BiPAP * Presence of spontaneous breathing activity (ventilator triggering), since 6 hours and no longer than 48 hours * Patient for full active management at this point. Exclusion Criteria: * Age \<18 years old * Pregnancy * Active air leaks * Moribund state * High ICP * Patient has passed a spontaneous breathing trial (if performed for clinical indication) * Known COPD with history of home oxygen therapy and/or non invasive ventilation and/or GOLD III-IV. Non invasive ventilation for sleep apnea is NOT an exclusion criteria.