- glasgow coma scale (gcs) < 13 - ph< 7,45, paco2 >45 mmhg - need for hfnc, cpap, niv or intubation - hemodynamic instability increase of 80-90 mmhg or reduction of 30-40 mmhg in systolic blood pressure - severe arrythmia of myocardial infarction - need for sedation - intolerance to pp - pregnancy - body mass index (bmi) > 35 kg/m2.

- glasgow coma scale (gcs) < 13 - ph< 7,45, paco2 >45 mmhg - need for hfnc, cpap, niv or intubation - hemodynamic instability increase of 80-90 mmhg or reduction of 30-40 mmhg in systolic blood pressure - severe arrythmia of myocardial infarction - need for sedation - intolerance to pp - pregnancy - body mass index (bmi) > 35 kg/m2.