- Discussion: 
- if PaO2 and pH are within normal limits and PaO2 is about 100 mm but only w/ a high FiO2 or on therapeutic levels of PEEP, pt should be left to breath spontaneously with therapeutic PEEP; 
- this is termed CPAP: continuous positive airway pressure; 
- as arterial oxygenation improves, PEEP can be reduced in small steps, sequentially following the arterial oxygenation tension; 
- when the PEEP level reaches 5 cm H2O, the possibility of extubation may be entertained