Current oxygen management in mechanically ventilated patients: a prospective observational cohort study

Purpose: Oxygen (O2) is the most common therapy in mechanically ventilated patients, but targets and dose are poorly understood. We aimed to describe current O2 administration and titration in such patients in an academic intensive care unit.

Materials and methods: In consecutive ventilated (>48 hours) patients we prospectively obtained fraction of inspired O2 (FiO2), pulse oximetry O2 saturation (SpO2) and arterial O2 tension (PaO2) every 6 hours. We calculated the amount of excess O2 delivery and the intensivists' response to hyperoxemia (SpO2>98%).

Results: During 358 mechanical ventilation days in 51 critically ill patients, median calculated excess O2 delivery was 3472 L per patient. Patients spent most of their time with their SpO2>98% (59% [29-83]) and PaO2 between 80 and 120 mm Hg (59% [38-72]). In addition, 50% of all observations showed hyperoxemia and 4% severe hyperoxemia (PaO2>202.5 mm Hg). Moreover, 71% of the calculated total excess 263,841 L of O2 was delivered when the Fio2 was 0.3 to 0.5. When hyperoxemia occurred with an Fio2 between 0.3 and 0.4, for 88% of episodes, no Fio2 adjustments were made.

Conclusions: Excess O2 delivery and liberal O2 therapy were common in mechanically ventilated patients. Current O2 therapy practice may be suboptimal and further investigations are warranted.