Inclusion Criteria:  Critical ill patients who used extracorporeal membrane oxygenation during their ICU stay. Patients were recruited from the general ICU of the second affiliated hospital of Zhejiang University, between March 2017 to March 2020.  Exclusion Criteria:  Patients who was less than 18 years old, had been proven or suspected neurological impairment, using extracorporeal membrane oxygenation less than 24 hours, severe head or spinal cord injury and pregnant woman.