There’s not much left of poor MONA. We’ve written on unnecessary O2 treatment before, ie the AVOID trial. And now, one of the large RCTs on the subject is out. The DETO2X-SWEDEHEART investigators (love the acronym) have published their findings in NEJM: Routine oxygen therapy gave no advantage over breathing ambient air.
Oxygen therapy is one of those treatments that show you you’re in a hospital – together with the bag of saline dripping through your i.v. But both are on their way out as routine treatment, and should be banned without a specific indication. That’s why this Swedish Group set out to measure the (lack of) effect from random/routine supplemental oxygen in non-hypoxemic patients.
They enrolled over 6000 patients with suspected MI and an SpO2 > 90% on pulse oximetry, and randomised them to oxygen on a facemask at 6 L/min for 6-12 hrs (median 11 hrs), or just breathing room air. Of the 6000 suspected MI’s they enrolled, 5000 patients ended up with the diagnosis of MI, and of those, 3000 had a STEMI, so the patient cohort seems representative for real life patients in the ED.
Patients on supplemental oxygen had an end of treatment median SpO2 of 99% vs 97% in the room air group. All endpoints were the same in both arms: The primary endpoint of death from any cause within 1 year after randomisation occured in 5% of patients in both groups. Also, 30-day mortality was the same, and peak troponin release was the same. Rehospitalisation for new MI within a year was the same. These findings were also consitent across all pre-defined subgroups.
1 in 12 from the room air group ended up receiving supplemental oxygen due to hypoxemia, defined as SpO2<90%. 1 in 50 patients in the routine oxygen group needed extra oxygen due to hypoxemia. And 1 in 12 receiving oxygen therapy stopped this oxygen therapy before protocol conclusion, presumably due to irritation from the dry air flow, mask discomfort or the oxygen tubing.
In this rather large multicenter RCT, routine oxygen treatment in patients with SaO2>90% showed no benefit over room air. On the flip side, routine oxygen therapy showed no harm in this study, as they found in the AVOID trial. Still, the conclusion must be to stop routinely administering oxygen to patients with an MI and normal oxygen saturation, but use supplemental oxygen on indication.
I would also say this can be extrapolated to other patient groups in addition to myocardial infarction, as saturation doesn’t go to 11. If Sats are above 95%, there should be no point in adding more oxygen. I’m particularly looking forward to removing the ATLS 10 L/min oxygen mask from all the normoxemic trauma patients arriving in our hospital. Only add if you cannot measure sats or if sats are low.