Sequential Use of Propofol/Midazolam and Dexmedetomidine for Sedation in Mechenical Ventialtion Patients in ICU.

For the patient who passed the screen of weaning from ventilation, the traditional sedation drug such as propofol and midazolam should be decreased or stopped, then it would induce the stress response and agitation, such as hypertension,tachycardia etc. In order to resolve that problem, the sedation should be given again. but if renewed to sedation, it would cause prolonged sedation and ventilation duration. So as to resolve above issues, after the patient passed the screen of weaning, sedation is changed to Dexmedetomidine, a new sedation drug, that could wake up at any time. So our study to compare the efficacy and safety of sequential sedation of propofol or midazolam and dexmedetomidine in mechanical ventilated ICU patients.