The study will be a multicenter, multinational, prospective single arm blinded study to validate DXT's performance to identify patients at increased risk of weaning failure during the spontaneous breathing trial (SBT). Continuous diaphragmatic excursion measurements by DXT will be conducted during the patients' first SBT. The recording shall be initiated 15 minutes prior to the first SBT and will end 15 minutes post SBT.

All patients on mechanical ventilation in the ICU meeting the eligibility criteria shall undergo a daily screen for weaning readiness. If any of the components of the daily screen is not met, the patient will not undergo a SBT that day and continued to be screened daily. Patients passing daily screening criteria shall automatically receive an SBT.

The SBT shall last for 30-120 minutes and be performed on continuous positive airway pressure up to 5 cm H2O and pressure support up to 7 cm H2O. The SBT shall be terminated and mechanical ventilation reinstituted at the original settings if the patient meets any of the SBT failure criteria.

A trial is considered successful and physicians will be asked to approve extubation when the patient can breathe spontaneously for the whole trial.

Patients shall be continued to be screened daily until extubation, 21 days after enrolment, performance of tracheostomy, death, or withdrawal of care. All patients shall be followed until hospital discharge or death.

Inclusion Criteria:

1. Patients willing and able to give informed consent (either themselves or next of kin)

2. Have undergone invasive mechanical ventilation > 24 hours

3. Ready to wean according to criteria (from the sixth international consensus conference on intensive care medicine):

   1. Adequate cough
   2. Absence of excessive tracheobronchial secretion
   3. Resolution of disease acute phase for which the patient was intubated
   4. Clinical stability, defined as stable cardiovascular status (i.e. fC < 140 beats·min-1, systolic BP 90-160 mmHg, no or minimal vasopressors) and stable metabolic status
   5. Adequate oxygenation, defined as SaO2 > 90% on < FIO2 0.4 (or PaO2/FIO2 > 150 mmHg) and PEEP < 8 cmH2O
   6. Adequate pulmonary function, i.e. fR < 35 breaths·min-1
   7. Adequate mentation, defined as no sedation or adequate mentation on sedation (or stable neurologic patient), i.e., patient awake, calm and responsive to simple orders (squeeze hand, knock the head, close the eyes), no agitation.

Exclusion Criteria:

1. Not registered with a social security system nor entitled to be
2. Central or spinal neurological injury involving central ventilatory control
3. Presence of a neuromuscular disease involving respiratory muscles
4. Use of muscle-paralyzing agents within 24h before the study, except if given for intubation
5. Known paralysis of a hemidiaphragm or suspicion of paralysis of a hemidiaphragm, defined by the radiographic evidence of elevation of a dome > 2.5 cm compared to the contralateral dome
6. Tracheostomy
7. Body mass index >35 kg/m2
8. Patient with therapeutic limitation, i.e. reduced expectancy to survive
9. Pregnant woman or protected adult

Patients under invasive mechanical ventilation in the intensive care unit