Extubation failure (EF) is independently associated with excess mortality of critically ill patients. To avoid EF, critically ill patients being weaned from invasive mechanical ventilation (IMV) perform spontaneous breathing trial (SBT), which is the litmus test for determining the ability to breathe without a ventilator.

Thus, the performance of the SBT during weaning from IMV to predict successful extubation is crucial. The investigators hypothesize that patients with EF increase arterial lactate concentration during SBT due to increased work of breathing and hypoxia.

The aim of this study is to evaluate the performance of variation in arterial lactate concentration before and after SBT in predicting successful extubation in critically ill patients.

Extubation failure (EF) is defined as the need for reintubation within 48-72 hour. This complication is independently associated with a seven-fold increased risk of death in critically ill patients.

To avoid EF, critically ill patients being weaned from invasive mechanical ventilation (IMV) perform spontaneous breathing trial (SBT), which is the litmus test for determining the ability to breathe without a ventilator. However, EF occurs in 10 to 20% of patients despite having successful SBT.

Thus, the performance of the SBT during weaning from IMV to predict successful extubation is crucial.

Previous studies of predictive markers of EF have been performed primarily to assess weaning failure from cardiac origin.

The investigators hypothesize that critically ill patients who are going to have EF increase arterial lactate concentration during SBT due to increased work of breathing and hypoxia, regardless of the cause of failure.

The aim of this study is to evaluate the performance of variation in arterial lactate concentration before and after SBT in predicting successful extubation in critically ill patients.

Inclusion Criteria:

• Adult ≥ 18 years old
• Intubation and ventilation > 24 hours

Exclusion Criteria:

• Patients under guardianship or curators
• Opposition to participation in the study by the patient or family member
• Patients with tracheotomy
• Pregnant or breast-feeding women

All patients hospitalized in intensive care, on invasive mechanical ventilation for more than 24 hours, and performing a spontaneous ventilation trial will be eligible for the study.