Normobaric Hyperoxia Stabilizing Ischemic Penumbra

Inclusion criteria: Age≥18岁 The signs and symptoms are consistent with anterior circulation infarction, and baseline NIHSS score：6-20 Level of consciousness on admission：0-1 mRS score before stroke: 0-1 Patients who did not receive revascularization therapy The time from onset (finally normal) to randomization is less than 24h Patients who signed informed consent CTA or MRA confirmed internal carotid artery occlusion or M1/M2 segment occlusion of middle cerebral artery The low-perfusion area with Tmax>6s was larger than the core infarction, and the mismatch ratio was greater than or equal to 1.8. Exclusion Criteria: Evidence of rapid improvement in neurological function and NIHSS score <6, or spontaneous recanalization before randomization The disease affecting assessment of baseline NIHSS score (dementia, epilepsy, neuromuscular disease, or psychiatric disease) Symptoms suggesting subarachnoid hemorrhage (even if CT scan is normal) Combined with the history, cerebral embolism due to sepsis or infective endocarditis was suspected Active or chronic obstructive pulmonary disease, pulmonary fibrosis, pneumonia, pleural effusion, acute respiratory distress syndrome, irregular breathing It is necessary to inhale (>3L/min) oxygen to maintain peripheral arterial oxygen saturation (SaO2>95%) Anemia or polycythemia vera or other conditions needing emergency oxygen patients Patients with upper gastrointestinal bleeding or nausea and vomiting can not complete inhalation oxygen using face mask Baseline blood glucose <2.78mmol/L or >22.2mmol/L Baseline platelet count <50×109/L Hereditary or acquired bleeding tendency, lack of coagulation factor, recent oral anticoagulant INR>3 or PPT more than 3 times Unstable vital signs (heart rate ≤50 beats/min or ≥120 beats/min, oxygen saturation ≤90%, R≥30 beats/min or ≤10 beats/min) Hypertension not controlled by medication: systolic blood pressure ≥185mmHg, or diastolic blood pressure ≥110mmHg Acute myocardial infarction suspected Pregnancy, Life expectancy <90 days Heart, liver and kidney failure Magnetic resonance contraindications Claustrophobia Allergic to contrast media Participating in other drug or device research