March 8, 2021
Background: Though oxygen is fundamental for life, supra-physiological levels can be deleterious. Several randomized controlled trials and meta-analyses have been conducted in the critically ill to determine whether a conservative oxygenation approach compared to a liberal oxygenation approach is beneficial. The OXYGEN-ICU trial was one of the first trials to explore this issue in 2016. It was a small, single centered trial with 434 ICU patients that showed a significantly lower ICU mortality in the conservative oxygenation group with an ARR 8.6%
1. ICU-ROX (Mechanically ventilated patients) and LOCO
2 (ARDS patients) were two more randomized trials that explored critically ill patients in the ICU with conflicting evidence on oxygen targets. There was no mortality benefit or ventilator free days in either study
2,3. Although in the LOCO2 trial there was a clinically relevant excess mortality in the conservative group of 14 percentage points higher than in the liberal group at 90 days (not statistically significant) Additionally, the LOCO
2 trial found a higher rate of intestinal ischemia in patients with a conservative oxygenation strategy
3. Based on these three trials it can be stated that both hyperoxia (SpO2 >97%) and hypoxemia (SpO2 <90%) should be avoided. An SpO2 of 92 to 96% (PaO2 60 to 90) would be the ideal target in these patients. Until now, there has not been any good data regarding oxygenation parameters in patients with acute hypoxemic respiratory failure.
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