Oxygen Therapy in Suspected Acute Myocardial Infarction
Hofmann R, James SK, Jernberg T et al.
Oxygen Therapy; Acute Myocardial Infarction
Background - The clinical effect of routine oxygen therapy in patients
with suspected acute myocardial infarction who do not have hypoxemia at
baseline is uncertain.
Methods - In this registry-based randomized
clinical trial, we used nationwide Swedish registries for patient
enrollment and data collection. Patients with suspected myocardial
infarction and an oxygen saturation of 90% or higher were randomly
assigned to receive either supplemental oxygen (6 liters per minute for 6
to 12 hours, delivered through an open face mask) or ambient air.
Results - A total of 6629 patients were enrolled. The median duration of
oxygen therapy was 11.6 hours, and the median oxygen saturation at the
end of the treatment period was 99% among patients assigned to oxygen
and 97% among patients assigned to ambient air. Hypoxemia developed in
62 patients (1.9%) in the oxygen group, as compared with 254 patients
(7.7%) in the ambient-air group. The median of the highest troponin
level during hospitalization was 946.5 ng per liter in the oxygen group
and 983.0 ng per liter in the ambient-air group. The primary end point
of death from any cause within 1 year after randomization occurred in
5.0% of patients (166 of 3311) assigned to oxygen and in 5.1% of
patients (168 of 3318) assigned to ambient air (hazard ratio, 0.97; 95%
confidence interval [CI], 0.79 to 1.21; P=0.80). Rehospitalization with
myocardial infarction within 1 year occurred in 126 patients (3.8%)
assigned to oxygen and in 111 patients (3.3%) assigned to ambient air
(hazard ratio, 1.13; 95% CI, 0.88 to 1.46; P=0.33). The results were
consistent across all predefined subgroups.
Conclusions - Routine use of supplemental oxygen in patients with suspected myocardial infarction who did not have hypoxemia was not found to reduce 1-year all-cause mortality. (Funded by the Swedish Heart-Lung Foundation and others; DETO2X-AMI ClinicalTrials.gov number, NCT01787110 .).
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