Head dOwn Position Before Endovascular Treatment for Large veSsel Occlusion (HOPES5)

Inclusion Criteria: * Age ≥ 18 years; * Patients with acute large vessel occlusion scheduled for endovascular thrombectomy within 24 hours of symptom onset; * Baseline National Institute of Health Stroke Scale (NIHSS) ≥ 6; * Expected waiting time from randomization to femoral artery puncture is more than 30 minutes; * ASPECTS/pc-ASPECTS score ≥ 6 on baseline non-contrast CT or DWI; * Modified Rankin Scale score before stroke onset ≤ 1; * Signed informed consent by patient or their legally authorized representative. Exclusion Criteria: * Hemorrhagic stroke: cerebral hemorrhage, subarachnoid hemorrhage; * Severe hepatic or renal dysfunction, increase in ALT or AST (more than 2 times of upper limit of normal value), increase in serum creatinine (more than 1.5 times of upper limit of normal value) or requiring dialysis; * Severe hypertension before randomization (systolic blood pressure \>185 mmHg or diastolic blood pressure \>110 mmHg); * Cardiac insufficiency (NYHA Class ≥II); * Pregnancy, plan to get pregnant or during lactation; * Patients at significant risk of aspiration (e.g., obvious nausea and vomiting); * The estimated life expectancy is less than 6 months due to other serious diseases; * Other conditions unsuitable for this clinical study assessed by researcher.