Written by Clay Smith
There was no difference in ventilator-free days in mechanically ventilated ICU patients when the SpO2 range was 90 to 97% vs 90% to no upper limit.
Why does this matter?
Yesterday we covered a retrospective study that suggested the ideal SpO2 range was 94-98%. OXYGEN-ICU was a RCT that suggested a mortality benefit with a conservative oxygen strategy. A meta-analysis called IOTA suggested the same. How does this hold up in another, slightly different RCT?
This ROX…or does it?
This was a RCT with 1000 ICU patients on mechanical ventilation. In the conservative oxygen group, the SpO2 alarm went off at an upper limit of 97%, and the FiO2 was turned down as low as 21%. In the usual care group, there was no upper limit SpO2 alarm. In both groups, the lower limit was 90%. Despite the conservative group having significantly more time with an FiO2 of 21% and SpO2 ≤96% vs the usual care group, there was no difference in the primary outcome of ventilator free days, nor was there a difference in 180-day mortality. Yesterday’s article found the ideal SpO2 range was 94-98%. Below 94%, mortality sharply increased. Could it have been that there was no apparent benefit in the conservative oxygen group because they set the lower limit too low in each group, mitigating the effect on outcomes? See figure below from yesterday’s article.
Conservative Oxygen Therapy during Mechanical Ventilation in the ICU. N Engl J Med. 2019 Oct 14. doi: 10.1056/NEJMoa1903297. [Epub ahead of print]
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