Retrospective analysis of the hemodynamic consequences of prehospital supplemental oxygen in acute stroke

Abstract Objective Hyperoxia, the delivery of high levels of supplemental oxygen (sO2) despite normoxia, may increase cerebral oxygenation to penumbral tissue and improve stroke outcomes. However, it may also alter peripheral hemodynamic profiles with potential negative effects on cerebral blood flow (CBF). This study examines the hemodynamic consequences of prehospital sO2 in stroke. Methods A retrospective analysis of adult acute stroke patients (aged ≥18 years) presenting via EMS to an academic Comprehensive Stroke Center between January 1, 2013 and December 31, 2017 was conducted using demographic and clinical characteristics obtained from Get with the Guidelines-Stroke registry and subjects' medical records. Outcomes were compared across three groups based on prehospital oxygen saturation and sO2 administration. Chi-square, ANOVA, and multivariable linear regression were used to determine if sO2 was associated with differences in peripheral hemodynamic profiles. Results All subjects had similar initial EMS vitals except for oxygen saturation. However, both univariate and multivariable analysis revealed that hyperoxia subjects had slightly lower average ED mean arterial pressures (MAP) compared to normoxia (Cohen's d = 0.313). Conclusions Prehospital-initiated hyperoxia for acute stroke is associated with a small, but significant decrease in average ED MAP, without changes in heart rate, compared to normoxia. While limited by the inability to link changes in peripheral hemodynamical profiles directly to changes in CBF, this study suggests that hyperoxia may result in a relative hypotension. Further studies are needed to determine if this small change in peripheral vascular resistance translates into a clinically significant reduced CBF.