Oxygen Concentration Target in Stroke Endovascular Treatment

Inclusion criteria 1. Age ≥18 years. 2. Anterior circulation occlusive stroke is confirmed by CT angiography (CTA), magnetic resonance angiography (MRA) or digital subtraction angiography (DSA), and occlusions of intracranial internal carotid artery (ICA) or M1 segment of the middle cerebral artery (MCA) were involved. 3. NIHSS score at admission: 6-20. 4. Randomization can be completed within 24 hours after stroke onset. Exclusion criteria 1. Stroke onset within 6-24 hours with a CT perfusion imaging (CTP)-assessed mismatched area\<15 ml. 2. Presence of anemia, defined as hemoglobin levels o below 120 g/L in men and below 110 g/L in women. 3. Pre-stroke modified Rankin scale (mRS) score ≥2. 4. Complicated by severe agitation and seizures. 5. Evidence of intracranial hemorrhage at admission. 6. Presence of chronic obstructive pulmonary disease, asthma, or other respiratory conditions, or requirement for daily supplemental oxygen or mechanical ventilation. 7. Baseline arterial blood gas analysis indicating impaired gas exchange: PaO2 \< 60 mmHg on room air, or oxygenation index (PaO2/FiO2) \< 300 mmHg with supplemental oxygen. 8. Emergency chest CT reveals significant pulmonary parenchymal infection. 9. An oxygen mask or ventilator must be used before anesthesia to maintain a SpO2≥94%. 10. Loss of airway protective reflex or vomiting aspiration upon admission.