The gold standard test to evaluate the readiness of a patient to be extubated is a spontaneous breathing trial. This trial is performed either using the T-piece disconnected from the ventilator, either using a low level of pressure support, with or without positive end-expiratory pressure. A higher rate of failure occurs during the T-piece than during the pressure support trial, but once the patient success once of these trials the rate of reintubation is similar. The prolongation of mechanical ventilation can lead to an increased risk of infectious complications, but premature extubation followed by reintubation is associated with increased morbidity and mortality. A major goal to liberate the patient from the ventilator is to recognize the readiness for extubation as soon and as reliably as possible. The stop of sedation and the performance of a spontaneous breathing trial daily diminish the duration of mechanical ventilation due to the recognition of the patient's capability of breathing spontaneously.