Patients in group N1 are treated with basic therapeutic measures which include reducing intracranial pressure with mannitol, hemostasis, acid inhibition, anti-infection, nutrition support and control of blood glucose, blood pressure and body temprature.

Patients in group N2 was treated with intravenous infusion of midazolam on the basis of basic treatment measures which include reducing intracranial pressure with mannitol, hemostasis, acid inhibition, anti-infection, nutrition support and control of blood glucose, blood pressure and body temprature.

For patients allocated into group N2, 2 mg midazolam will be injected intravenously, and then it will be given at 0.05-0.1 mg/(kg·h) by intravenous infusion. If a surgery is needed, infusion of midazolam will begin 3 hours after the operation and continue for at least 72 hours. During the sedation with midazolam, BIS should be kept at 60 to 80.

Morphine can be used to supply adequate analgesia.

N1 group: blood samples will be collected when the patient is admitted to ICU, 24 h, 48 h and 72 h after the admission

N2 group: blood samples will be collected before the use of midazolam, 24 h, 48 h and 72 h after the use

Blood sample will be collected every time from the radial artery and the jugular bulb separately. The blood sample will be used for blood gas analysis

Detail parameters by blood test: levels of lactic acid, oxygen saturation(SaO2), partial pressure of oxygen(Pa02), jugular bulb venous oxygen saturation(SjvO2), jugular bulb oxygen partial pressure(PjvO2), hemoglobin(Hb)

Calculated parameters: arterial oxygen content(Ca02), jugular venous oxygen saturation (SjvO2), arterial venous oxygen content difference(Da-jvO2), cerebral extraction of oxygen(CERO2), Lactate differences between jugular and arterial blood(AVDL) and Cerebral lactate acid production(CLP)

N1: blood samples and cerebrospinal fluid are collected when the patient is admitted to ICU, 24 h, 48 h and 72 h after the admission

N2: blood samples and cerebrospinal fluid are collected before the use of midazolam, 24 h, 48 h and 72 h after the use

every time, 3 ml blood sample will be collected from the jugular bulb and 2 ml cerebrospinal fluid will be collected at the corresponding time

The blood sample will be anticoagulated by EDTA and then it will be centrifuged at 3000 r/min for 10 minutes within 30 minutes from the collection. The supernatant liquid will be stored in the freezer at -70℃.

The cerebrospinal fluid centrifuged at 3000 r/min for 10 minutes, and then the supernatant liquid will be stored in the freezer at -80℃.

Detail parameters: sFkn and IL-6 levels of the blood sample and CSF will be tested 2 times by ELISA and then take the average.