The aim of this study is to investigate the association between the severity and duration of intraoperative hypotension and the incidence of perioperative stroke after non-cardiac and non-neurologic surgeries.The secondary aim of this study is to confirm the potential risk factors of the perioperative stroke.

Optimized intraoperative management may play an important role in perioperative stroke prevention. Maintaining blood pressure near preoperative baseline values may help decrease the incidence of stroke, however the related evidence is limited.Therefore, this study is to investigate the association between intraoperative hemodynamic variable and the risk of perioperative stroke after non-cardiac and non-neurologic surgeries. The secondary aim of this study is to establish the potential risk factors of the perioperative stroke.

Inclusion Criteria:

1. Patients underwent surgeries in First hospital affiliated to Shandong First Medical University from January 2013 to October 2019
2. Age>18 or older

Exclusion Criteria:

1. Patients received local infiltration anesthesia
2. Patients underwent total intravenous anesthsia without tracheal intubation or Laryngeal Mask Airway insertion
3. Major vascular operation
4. Neurologic surgery
5. Cariac surgery
6. Intraoperative blood pressure measurements or postoperative neuroimagings measurements are not available
7. History of severe neurological or psychiatric disease

All patients who underwent surgical procedures under anesthesia at Qianfoshan Hospital, First Hospital affiliated to Shandong First Medical University during the period from January, 2013, to October, 2019, will be included.