Until recently, midazolam and opioid combination regimen recognized as a standard therapy is widely used, but the sedative effect is insufficient and intermittent paradoxical reaction has been questioned. Another drug, such as propofol, has been known that the sedative effect is superior one of the midazolam but disappointed due to narrow therapeutic range of respiratory distress and absence of antagonist. Meanwhile, recently up-coming drug, etomidate which is a modulator of GABA-A receptor has been known that it maintains the appropriate sedative levels and affects little effects on respiratory system.