Efficacy and Safety of Non-sedation Trial in Patients After Neurosurgical Craniotomy

Patients eligible for this study will undergo non-sedation strategy, which continuous analgesia without sedation is performed with remifentanil. The remifentanil will be titrated (from 0.1µg/kg/min to 0.2ug/kg/min) every 10-15 minutes to achieve the goal for sedation (RASS score maintaining -2 to + 1). The patients in the non-sedation trial do not receive any sedatives but could receive bolus doses (2.5 or 5mg) of morphine for analgesia.