Background: The weaning failure has prevalence between 15 to forty percent depending of various factors. Level of consciousness, heart failure, advanced age, chronic obstructive pulmonary disease (COPD), glottic edema, cancer, neuromuscular diseases, metabolic disorders, local resources and many others factors contribute to this sometimes grim situation. In the last few years, efforts to reduce this figure were using non-invasive ventilation (NIV) or High Flow Nasal Cannula (HFNC) after extubation, cuff leak text to detect airway caliber reduction had some impact in improving the weaning failure but still we have significant failures rates. Aim: For a long time we have observed that many patients fail the weaning process due to lack of protect the airways. They aspirate saliva and fails nearly immediately after extubation. The evaluation of the ability to protect the airways in intubated patients is not an easy task. This was the reason to find a marker to diagnose oropharyngeal dysphagia in intubated patients before extubation. Methods: This prospective observational study evaluated 112 consecutive mechanically ventilated patients. Saliva and tracheobronchial secretions were collected, and the tracheal to salivary amylase’s activities ratio were determined. We called this parameter as amylase index. Variables that could influence weaning failure and mortality were quantified and analyzed. We evaluated the presence heart failure, age, chronic obstructive pulmonary disease, glottic edema, cancer, neuromuscular diseases, and level of consciousness, as a cause of weaning failure. The Statistical Package for the Social Sciences (SPSS) version 20 for Windows (IBM Corporation, Armonk, NY, USA) was used for the statistical analysis. The Student t test was used for normally distributed continuous variables; a chi-square test, for categorical variables, binary logistic regression and descriptive statistics. All p values were two-tailed. Results: We found, in order of importance, that the level of consciousness, heart failure, and incomplete resolution of lung disease, saliva aspiration (amylase index), muscle weakness, and laryngeal edema were the causes of weaning failure. Further, the amylase index showed a strong correlation with mortality and weaning failure in patients who were mechanically ventilated. Conclusion: Amylase index is another factor to be considered during the weaning process.