Post extubation respiratory failure occur in 30% of extubated patients. More than 50% of them required reintubation. Noninvasive positive pressure ventilation (NIV) had been reported as an effective tool to prevent post extubation respiratory failure. Recently, high flow oxygen nasal cannula (HFNC) had been successfully used to prevent post extubation respiratory failure and prevent reintubation in comparable with NIV among post cardiothoracic surgery and high risk for reintubated patients. There was no information about HFNC versus NIV in prevention of reintubation among severe sepsis or septic shock patients.