Prehospital supplemental oxygen for acute stroke - A retrospective analysis

Objective: Brief early administration of supplemental oxygen (sO₂) to create hyperoxia may increase oxygenation to penumbral tissue and improve stroke outcomes. Hyperoxia may also result in respiratory compromise and vasoconstriction leading to worse outcomes. This study examines the effects of prehospital sO₂ in stroke.

Methods: This is 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. Demographic and clinical characteristics obtained from Get with the Guidelines-Stroke registry and subjects' medical records were compared across three groups based on prehospital oxygen saturation and sO₂ administration. Chi-square, ANOVA, and multivariate logistic regression were used to determine if sO₂ status was associated with neurological outcomes or respiratory complications.

Results: 1352 eligible patients were identified. 62.7% (n = 848) did not receive sO₂ ("controls"), 10.7% (n = 144) received sO₂ due to hypoxia ("hypoxia"), and 26.6% (n = 360) received sO₂ despite normoxia ("hyperoxia"). The groups represented a continuum from more severe deficits (hypoxia) to less severe deficits (controls): mean prehospital GCS (hypoxia -12, hyperoxia - 2, controls - 14 p ≤ 0.001), mean initial NIHSS (hypoxia - 15, hyperoxia - 13, controls - 8 p < 0.001). After controlling for potential confounders, all groups had similar rates of respiratory complications and favorable neurological outcomes.

Conclusions: Hyperoxic subjects had no significant increase in respiratory complications, nor did they differ in neurologic outcomes at discharge when controlling for confounders. While limited by the retrospective nature, this suggests brief, early sO₂ for stroke may be safe to evaluate prospectively.