patients with respiratory failure either type I or type II planned for extubation will be divided into 2 groups post extubation :~Group I: will receive high flow nasal cannula giving oxygen 60 litres / minute group II: will receive nasal cannula up to 10 litres / minute~Data of the patients will be collected for 28 days postextubation and analysed
comparing high flow nasal cannula & conventional oxygen tharapy in post-extubation period for patients mechanically ventilated due to respiratory failure regarding re-intubation rate, ICU outcome &28 days mortality