Adjuvant High-Flow Normobaric Oxygen After Mechanical Thrombectomy for Anterior Circulation Stroke: a Randomized Clinical Trial

Abstract

Adjuvant neuroprotective therapies for acute ischemic stroke (AIS) have demonstrated benefit in animal studies, albeit without human translation. We investigated the safety and efficacy of high-flow normobaric oxygen (NBO) after endovascular recanalization in anterior circulation stroke. This is a prospective randomized controlled study. Eligible patients were randomized to receive high-flow NBO by a Venturi mask (FiO₂ 50%, flow 15 L/min) or routine low-flow oxygen supplementation by nasal cannula (flow 3 L/min) after vessel recanalization for 6 h. Patient demographics, procedural metrics, complications, functional outcomes, symptomatic intracranial hemorrhage (sICH), and infarct volume were assessed. A total of 91 patients were treated with high-flow NBO. NBO treatment revealed a common odds ratio of 2.2 (95% CI, 1.26 to 3.87) favoring the distribution of global disability scores on the mRS at 90 days. The mortality at 90 days was significantly lower in the NBO group than in the control group, with an absolute difference of 13.86% (rate ratio, 0.35; 95% CI, 0.13-0.93). A significant reduction of infarct volume as determined by MRI was noted in the NBO group. The median infarct volume was 9.4 ml versus 20.5 ml in the control group (beta coefficient, - 20.24; 95% CI, - 35.93 to - 4.55). No significant differences were seen in the rate of sICH, pneumonia, urinary infection, and seizures between the 2 groups. This study suggests that high-flow NBO therapy after endovascular recanalization is safe and effective in improving functional outcomes, decreasing mortality, and reducing infarct volumes in anterior circulation stroke patients within 6 h from stroke onset.

Keywords: Oxygen supplement; endovascular recanalization; functional prognosis.; large vessel occlusion; neuroprotection.

Fig. 1

Flow and timeline of participants enrolled

Fig. 2

Modified Rankin Scale score in AIS patients after vessel recanalization at 90 days. Image of scores on the modified Rankin Scale range from 0 to 6 in AIS patients after vessel recanalization at 90 days; 0 indicating no symptoms, 1 no clinically significant disability, 2 slight disability, 3 moderate disability, 4 moderately severe disability, 5 severe disability, and 6 death. Significant difference between the NBO and control groups was noted in the overall distribution of scores (common odds ratio, indicating the odds of improvement of 1 point on the modified Rankin Scale, 2.2; 95% confidence interval, 1.26 to 3.87), favoring NBO

Fig. 3

Infarct volume at 24 h after vessel recanalization. Comparison on infarct volume at 24 h after vessel recanalization between the 2 groups, demonstrating a significant reduction of infarct volume determined by MRI in the NBO group

Fig. 4

Analysis of functional independence at 90 days in subgroups. Functional independence was defined as a score on the modified Rankin Scale of 0, 1, or 2. p values were based on the Breslow–Day test for homogeneous odds ratios across subgroups. Squares indicate point estimates for treatment effects, and the size of the square is proportional to the precision of the estimate. NIHSS = scores on the National Institutes of Health Stroke Scale, range from 0 to 25, with higher scores indicating more severe neurologic deficits, the threshold of 17 was the threshold used in stratifying randomization; ASPECTS = Alberta Stroke Program Early CT Score, ranges from 6 to 10, with higher scores indicating a smaller infarct core; MCA = middle cerebral artery segment; ICA = internal carotid artery; P-ICA = proximal segment of internal carotid artery occlusion combined with intracranial large artery occlusion; IV rt-PA = intravenous recombinant tissue plasminogen activator