Relation of inspired oxygen fraction to hypoxemia in mechanically ventilated adults

To evaluate the recommendation that all adult patients started on mechanical ventilation (MV) should have an initial fraction of inspired oxygen (FIO2) of 1.0, 207 consecutive adult patients started on MV in the critical care units were studied. The initial FIO2, the resultant PaO2, and the level of training of the physician ordering the initial ventilator settings were recorded for each patient. Patients treated with an initial FIO2 less than 1.0 had a PaO2 under 60 torr significantly more often than did patients treated with FIO2 of 1.0. Staff-level physicians tended to employ an initial FIO2 less than 1.0 more often than did physicians-in-training, and the latter had a 19% incidence of PaO2 less than 60 torr, while staff-level physicians had no PaO2 values less than 60 torr when using an initial FIO2 less than 1.0. It is concluded that all adult patients started on MV should receive an initial FIO2 of 1.0, especially when the physician ordering the initial FIO2 is a physician-in-training.