The objects in sequential group who met the following criteria including those with oxygen index ( PaO@/FiO@ ) reaching @-@ mmHg ( @ mmHg = @ kPa ) under PEEP of @ cmH@O ( @ cmH@O = @ kPa ) , and pressure support of @ cmH@O , and most acute infiltrating lesions having resolved on chest imaging , received noninvasive ventilation ( NIV ) immediately after extubation , and patients in control group continued to have invasive mechanical ventilation via intubation or tracheostomy with an endotracheal tube .