Reperfusion With Hypothermia in Acute Ischemic Stroke

Inclusion Criteria: * Aged 18-80 years; * Patients with symptoms consistent with an AIS; * Pre-stroke mRS score 0-1; * NIHSS score 6-30 at the time of randomization; * Computed Tomography Angiography (CTA) or Magnetic Resonance Angiography(MRA) proved occlusion of Internal Carotid Artery (ICA) terminal or M1 segment of Middle Cerebral Artery; * Imaging showed massive infarction: within 24h of onset and Alberta Stroke Program Early CT Score (ASPECTS) \< 3, and large infarct core 70-100 ml (CT perfusion \[ Relative Cerebral Blood Flow (rCBF) \< 30%\]); within 24h of onset and ASPCECTS score 3-5 (based on NCCT); ASPECTS \> 5, within 6h-24h of onset,and large infarct core 70-100 ml (CTP \[rCBF \< 30%\]); * Successful recanalization of occluded vessel (modified Thrombolysis in Cerebral Infarction (mTICI) scores 2b/3) after EVT; * Patients and/or their families agreed to enter the trial. Exclusion Criteria: * CT after reperfusion showed PH2 hemorrhagic transformation; * bilateral stroke or multiple intracranial occlusions; * known presence of Inferior Vena Cava (IVC) filter; * end-stage renal disease on hemodialysis; * known hemorrhagic diathesis, coagulation factor deficiency or platelet count \< 5 × 109/L, International Normalized Ratio(INR) \> 1.7; * known hypersensitivity to meperidine, buspirone, midazolam and other sedative and analgesic drugs; * pregnant women; * combined malignant tumors, sepsis, hypothyroidism; * unstable vital signs/dying state, requiring vasoactive drugs to maintain hemodynamic stability and in the incremental phase; * cardiac function grade 4/severe liver and kidney dysfunction; * has participated in other drugs or device clinical trials that may have an impact on the current study; * other reasons lead the investigator to believe that patients are not suitable to continue hypothermia treatment.