Impact of early hyperoxia on 28-day in-hospital mortality in patients with myocardial injury

Despite relevant evidence that supplemental oxygen therapy can be harmful to patients with myocardial injury, the association between hyperoxia and the clinical outcome of such patients has not been evaluated. We assessed whether early hyperoxia negatively affects outcomes in hospitalized patients with myocardial injury. This was a retrospective study conducted at a tertiary referral teaching hospital. Between January 2010 and December 2016, 2,376 consecutive emergency department patients with myocardial injury, defined as a peak troponin-I level ≥ 0.2 ng/mL, within the first 24 hours of presentation were included. The metrics used to define hyperoxia were the maximum average partial pressure of oxygen (PaO2MAX), average partial pressure of oxygen (PaO2AVG), and area under the curve during the first 24 hours (AUC24). The association between early hyperoxia within 24 hours after presentation and clinical outcomes was evaluated using multiple imputation and logistic regression analysis. The primary outcome was 28-day in-hospital mortality. The secondary outcomes were new-onset cardiovascular, coagulation, hepatic, renal, and respiratory dysfunctions (sequential organ failure sub-score ≥ 2). Compared with normoxic patients, the adjusted odds ratios (ORs) for PaO2MAX, PaO2AVG, and AUC24 were 1.55 (95% confidence interval (CI) 1.05-2.27; p = 0.026), 2.13 (95% CI 1.45-3.12; p = 0.001), and 1.73 (95% CI 1.15-2.61; p = 0.008), respectively, in patients with mild hyperoxia and 6.01 (95% CI 3.98-9.07; p < 0.001), 8.92 (95% CI 3.33-23.88; p < 0.001), and 7.32 (95% CI 2.72-19.70; p = 0.001), respectively, in patients with severe hyperoxia. The incidence of coagulation and hepatic dysfunction (sequential organ failure sub-score ≥ 2) was significantly higher in the mild and severe hyperoxia group. Hyperoxia during the first 24 hours of presentation is associated with an increased 28-day in-hospital mortality rate and risks of coagulation and hepatic dysfunction in patients with myocardial injury.