 In the process of liberation or discontinuation from mechanical ventilation also commonly referred as weaning the goal is to achieve spontaneous breathing and ultimately extubation. Weaning failure occurs in up to 25 of patients who meet criteria for weaning, especially in those with underlying COPD or heart failure 1. Weaning failure is well known to prolong intensive care unit ICU stay, and to increase morbidity and mortality in critically ill patients. Early identification and treatment of causes of weaning failure is of paramount importance to improve outcome in difficult to wean patients. 