Numerous objective indices have been studied to predict failure of ventilator liberation or weaning. None of these indexes alone are sufficiently sensitive and specific to be useful in predicting the success of ventilation discontinuation in an individual patient.
PaO2/FiO2 ratio is the ratio of arterial oxygen partial pressure (PaO2 in mmHg) to fractional inspired oxygen (FiO2 expressed as a fraction, not a percentage)
Non-invasive ventilation (NIV) is the application of respiratory support via a sealed face-mask, nasal mask, mouthpiece, full face visor or helmet without the need for intubation