The most feared complication of COVID-19 infection is the occurrence of an acute respiratory distress syndrome (ARDS) that requires ICU admission and prolonged mechanical ventilation in more than 2% of the affected patients. Establishing the correct time to extubate mechanically ventilated patients is a crucial issue in the critical care practice. Delayed extubation has several consequences such as patient's mortality, health-care-related complications, neuropsychological adverse events. The aim of the INVICTUS study is to evaluate whether a CTUS-based MV weaning strategy could reduce the duration of mechanical ventilation of ARDS COVID-19 ICU patients by 72 hours, compared with usual medical care.

Identifying patients at risk for postextubation distress using standard clinical criteria and the only available test the investigators have, that is, the spontaneous breathing trial (SBT) remains a challenging issue2. A cumulative body of evidence suggest that the decision to attempt extubation might be assisted by the use of thoracic ultrasound. This non-invasive, reproducible and fully bedside approach is able to provide accurate information about respiratory, cardiac and neuromuscular functions which are independent predictors of extubation outcome. Recently, the investigators have demonstrated that a combined thoracic ultrasound (CTUS) strategy based on lung ultrasound, echocardiography and diaphragm ultrasonographic assessment data performs better than routine clinical assessment to evaluate extubation readiness in medical and surgical ICU patients3. CTUS appears as a unique point of care precision medicine prognostic and diagnostic tool for the management of patients experiencing ARDS. Based on those premises, the investigators hypothesize that CTUS-based MV weaning strategy could reduce the duration of mechanical ventilation of ARDS COVID-19 ICU patients by 72 hours, compared with usual medical care. This research is a national, multicenter, randomized, controlled, open-label, in parallel group. Patients will be randomized on 1:1 CTUS strategy group or standard strategy group, daily daily followed until extubation+48hours, reassessed at day 28 and at 3 months. In CTUS strategy group, a combined CTUS examination will be performed until the day of patient extubation. CTUS examination will consist on a fully bedside ultrasonographic assessment of lung, cardiac and diaphragm functions. In standard strategy group, from the day of patient's inclusion and beyond every day, the clinical team in charge of patients will decide to perform or not an SBT following current recommendations2. These criteria are mainly based on clinical data and do not include any specific ultrasound assessment.

Inclusion Criteria:

• ICU admission for severe acute respiratory distress syndrome (ARDS, as previously defined5 by a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of less than 150) related to COVID-19.
• Non paralyzed because of neuromuscular blocking agents.
• Ventilated patient in pressure support mode for at least 6 hours and at most 24 hours.
• Surrogate decision maker's consent.
• Affiliated person or beneficiary of a social security scheme.

Exclusion Criteria:

• Reduction or cessation of active treatment.
• Paraplegia with medullar level more than T8.
• Tracheostomy before hospital admission.
• History of severe respiratory illness.
• Patient under juridical protection.
• Pregnancy or nursing woman.
• Enrolled in another trial evaluating mechanical ventilation.