All patients who satisfy the inclusion criteria will be included in the study after obtaining a written informed consent from the patients next of kin. When an SBT is planned by the treating physician, the investigator will perform the ultrasound measurements. First, the patients’ demographic characters like age, sex, nature of ICU (Medical /Surgical), presence of comorbid condition, primary diagnosis of the patient, indication of ICU admission, APACHE II and SOFA scores at ICU admission, duration of ICU stay, duration of mechanical ventilation prior to the SBT will be recorded. Baseline hemodynamic parameters such as heart rate (HR), systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), oxygen saturation (SpO2), type of respiratory support, PaO2/FiO2 ratio, cumulative fluid balance after ICU admission at the time will also be noted.

Immediately before SBT, sEMG of diaphragm will be noted from two surface electrode by a commercially available sEMG device (PheezeeⓇ, Sartoon Labs). Another sets of reading of sEMG will be obtained as the end of SBT protocol irrespective of the decision of extubation. All patients will be followed 48 hours after extubation to note requirement of oxygen therapy (oxygen by face mask, non-invasive ventilation and HFNC) and requirement for re-intubation within 48 hours.