* Apnea * Deteriorating Alveolar Ventilation - pH < 7.25 - Rising PaCO2: in appropriate clinical setting, especially with falling pH; PaCO2 > 60 mm Hg; * Inadequate
oxygenation: (Pul. Edema, Consilidation, Atelectasis); - Falling PaO2 - PaO2 < 70 mm Hg on 50% O2 by mask; - PaO2 < 55 mm on room air in the appropriate clinical setting
