Extubation is a critical process in the ICU. Pulmonary USG has different applications, those that predict success in extubation, such as the diaphragmatic excursion time index (DEIT).To determine the diaphragmatic excursion time index is a predictor of the success of weaning off mechanical ventilation in patients in the intensive care unit.Diagnostic performance study in patients in the ICU and in the extubation protocol. Diaphragmatic measurement by USG, evaluating DEIT; cut-off point of 2.42 ± 1.55 cm/s. In the hypothesis test, a JI square was carried out between the two qualitative variables, in order to accept or reject H0, with a statistical significance of p < 0.05 to determine if there is dependence between the dependent and independent variables.Total of 200 patients from the population, with successful extubation in 52.5% and extubation failure in 47.5%. Prognostic values of the DEIT were: S: 77.1% (68.2-84.1%), E: 56.8% (46.8-66.3%). ROC curve for ITED, AUC of 0.665 (0.58-0.74; p = 0.001). In secondary objectives, a correlation was made between ventilatory and demographic variables for successful extubation; with FvT (Rho: 0.680, p = 0.0001).The DEIT for withdrawal of mechanical ventilation has low sensitivity and specificity as a result of successful extubation. The finding that DEIT is not an adequate predictor determining the outcome of successful extubation.