Hyperoxemia, often overlooked in critically ill patients, is common and may have adverse consequences.


To evaluate the incidence of hyperoxemia induced by oxygen therapy in nonsurgical critically ill patients at intensive care unit (ICU) admission and the association of hyperoxemia with hospital mortality.


This prospective cohort study included all consecutive admissions of nonsurgical patients aged 18 years or older who received oxygen therapy on admission to the Hospital Santa Luzia Rede D’Or São Luiz adult ICU from July 2018 through June 2021. Patients were categorized into 3 groups according to Pao2 level at ICU admission: hypoxemia (Pao2<60 mm Hg), normoxemia (Pao2= 60–120 mm Hg), and hyperoxemia (Pao2 >120 mm Hg).


Among 3088 patients, hyperoxemia was present in 1174 (38.0%) and was independently associated with hospital mortality (odds ratio [OR], 1.32; 95% CI, 1.04–1.67; P=.02). Age (OR, 1.02; 95% CI, 1.02–1.02; P<.001) and chronic kidney disease (OR, 1.55; 95% CI, 1.02–2.36; P=.04) were associated with a higher rate of hyperoxemia. Factors associated with a lower rate of hyperoxemia were Sequential Organ Failure Assessment score (OR, 0.88; 95% CI, 0.83–0.93; P<.001); late-night admission (OR, 0.80; 95% CI, 0.67–0.96; P=.02); and renal/metabolic (OR, 0.22; 95% CI, 0.13–1.39; P<.001), neurologic (OR, 0.02; 95% CI, 0.01–0.05; P<.001), digestive (OR, 0.23; 95% CI, 0.13–0.41; P<.001), and soft tissue/skin/orthopedic (OR, 0.32; 95% CI, 0.13–0.79; P=.01) primary reasons for hospital admission.


Hyperoxemia induced by oxygen therapy was common in critically ill patients and was linked to increased risk of hospital mortality. Health care professionals should be aware of this condition because of its potential risks and unnecessary costs.

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