Oxygen targets in patients with septic shock: a retrospective cohort study on the association between hyperoxia and mortality.

BACKGROUND

In critically ill patients with septic shock, adequate oxygenation is crucial and hypoxia should be avoided. However, hyperoxia has been linked to the formation of reactive oxygen species, inflammation, and vasoconstriction, which could potentially harm critically ill intensive care patients. Therefore, this study aimed to examine the association between oxygen exposure and mortality and to define optimal oxygen target ranges for this specific group of patients.

METHODS

This retrospective, single-center cohort study examined the influence of arterial oxygen partial pressure (PaO) on in-hospital mortality in intensive care unit (ICU) patients with septic shock. Time-weighted mean PaO values for days 1, 2-3, 4-7, and 8-14 were calculated and analyzed using multivariable binary logistic regression models and relative distribution analyses, adjusting for age and sepsis-related organ failure assessment (SOFA) score on day 1. Additionally, PaO integrals above thresholds of 80, 100, 120, and 150 mmHg were calculated for periods from admission up to days 1, 3, 7, and 14, with multivariable adjusted binary logistic regression analyses performed.

RESULTS

A total of 2,647 cases from 2,463 patients, identified between January 2016 and December 2022, met the inclusion criteria. The time-weighted mean PaO values associated with the lowest mortality were 92, 81, 83, and 85 mmHg for days 1, 2-3, 4-7, and 8-14, respectively. The optimal oxygen target range decreased over time: from 77 to 103 mmHg on day 1 to 72 to 90 mmHg on days 2 and 3, and to 74 to 92 mmHg for days 4 to 7. Additionally, PaO integrals above all set thresholds of 80, 100, 120, and 150 mmHg for all periods were found to be independently associated with increased in-hospital mortality ( < 0.05 for day 1;  < 0.001 for up to days 3, 7, and 14).

CONCLUSION

In this cohort, the PaO oxygen target range associated with the lowest mortality in patients with septic shock was approximately 80-105 mmHg on the first day of treatment, decreasing to approximately 75-90 mmHg during intensive care therapy.