Studies from our lab indicated that long-term sedation is protective in mice with midbrain infarct. To assess whether post-operative sedation has protective effects on clinical outcomes in patients with ischemic stroke undergoing endovascular thrombectomy (ET), a multi-center, randomized clinical trial will be carried out (POSET study). In POSET study, patients receiving ET for acute ischemic stroke under general anesthesia will be randomly assigned to the control group (Con group) and the post-operative sedation group (POS group). Patients in the Con group will be recovered and extubated immediately after the surgery, whereas those in the POS group will be sedated with propofol and dexmedetomidine for another 6hrs before extubation. The primary endpoint is the score on the modified Rankin Scale assessed at 90±7 days after randomization. The hypothesis is that patients in the POS group will have improved clinical outcome in 3 months after surgery.