Associations of arterial oxygen partial pressure with all‑cause mortality in critically ill ischemic stroke patients: a retrospective cohort study from MIMIC IV 2.2.

BACKGROUND

As a supportive treatment, the effectiveness of oxygen therapy in ischemic stroke (IS) patients remains unclear. This study aimed to evaluate the relationships between arterial partial pressure of oxygen (PaO) and both consciousness at discharge and all-cause mortality risk in ICU IS patients.

METHODS

Blood gas measurements for all patients diagnosed with IS were extracted from the MIMIC-IV database. Patients were classified into four groups based on their average PaO during the first ICU day: hypoxemia (PaO < 80 mmHg), normoxemia (PaO 80-120 mmHg), mild hyperoxemia (PaO 121-199 mmHg), and moderate/severe hyperoxemia (PaO ≥ 200 mmHg). The primary endpoint was 90-day all-cause mortality. Secondary outcomes included the level of consciousness at discharge, assessed by the Glasgow Coma Scale (GCS), and 30-day all-cause mortality. Multivariate Cox regression and Restricted cubic spline (RCS) analysis were used to investigate the relationship between mean PaO and mortality, and to assess the nonlinear association between exposure and outcomes.

RESULTS

This study included a total of 946 IS patients. The cumulative incidence of 30-day and 90-day all-cause mortality increased with decreasing PaO levels. RCS analysis revealed a nonlinear relationship between PaO and the risk of 30-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001), as well as a nonlinear association between PaO and 90-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001). The results remained consistent after excluding the small subset of patients who received reperfusion therapy. Sensitivity analysis indicated that the favorable impact on survival tends to increase with the extended duration of elevated PaO.

CONCLUSIONS

For IS patients who do not receive reperfusion therapy or whose recanalization status is unknown, a lower PaO early during ICU admission is considered an independent risk factor for short-term and recent mortality. Adjusting respiratory parameters to maintain supraphysiological levels of PaO appears to be beneficial for survival, although this finding requires further validation through additional studies.

TRIAL REGISTRATION

Not applicable.