Intubation and mechanical ventilation are related with several complications. This increased the risk of mortality of intensive care patients. So, we always look for an early extubation when patients are recovered for the trigger disease. In spite of standardized manoeuvres to decided readiness for extubation these are not quite good because it has been described a failure extubation rate of 5% and a reintubation rate of 15%. Furthermore several risk factors has been associated with a major failure rate:>65 years old, congestive cardiac insufficiency, chronic obstructive pulmonary disease, APACHE II >12 the extubation day, BMI >30, ineffective cough, a lot of bronchial secretions (as the need for >2 endotracheal suctioning in the last 8h before extubation), failure of a previous SBT,alterations of high respiratory tract or intubation for more than 7 days.Patients without any of these factors risk has an extubation failure rate of 10% while if any of these are present extubation failure increase to 30%.