Diaphragmatic and Pulmonary US for Extubation Success Prediction

The primary objective is to assess whether the fraction of diaphragmatic shortening in combination with the presence / absence of alveolar-interstitial syndrome evaluated through chest ultrasound may predict successful extubation in adult patients hospitalized in the intensive care unit. The investigators' null hypothesis is the fraction of diaphragmatic shortening in combination with the presence / absence of alveolar-interstitial syndrome evaluated through chest ultrasound can not predict the success of extubation in adult patients hospitalized in the intensive care unit. The alternative hypothesis is the fraction of diaphragmatic shortening in combination with the presence / absence of alveolar-interstitial syndrome evaluated through chest ultrasound may predict successful extubation in adult patients hospitalized in the intensive care unit. The study is a no experimental study of diagnostic test, prospective with longitudinal capture. The study will consist of two parts: the first with the aim of finding the values best combination of sensitivity and specificity compared to extubation success for diaphragmatic shortening fraction and the number of lung quadrants with lines B. In the second part the study will make the prospective validation of these values.