In group A, propofol (1%) was mixed with etomidate in the ration of 1:1 (volume). The mixture will be injected continuously until the eyelash reflex disappears. During the operation, supplementary mixture will be administered if the patient has spontaneous movement that hampered the conduct of the procedure.

In group B, propofol (1%) was mixed with etomidate in the ration of 7:5 (volume). The mixture will be injected continuously until the eyelash reflex disappears. During the operation, supplementary mixture will be administered if the patient has spontaneous movement that hampered the conduct of the procedure.

In group C, propofol (1%) will be injected continuously until the eyelash reflex disappears. During the operation, supplementary propofol will be administered if the patient has spontaneous movement that hampered the conduct of the procedure.

Every patient enrolled in the study will be given 15 mg pentazocine before induction.

Heart rate will be recorded immediately when the patient arrived at the operating room, 2 min, 4 min, 6 min, 8 min and 10 minutes after the the injection of propofol or mixture of propofol and etomidate.

Blood pressure will be recorded immediately when the patient arrived at the operating room, 2 min, 4 min, 6 min, 8 min and 10 minutes after the the injection of propofol or mixture of propofol and etomidate.

Pulse oxygen saturation will be recorded immediately when the patient arrived at the operating room, 2 min, 4 min, 6 min, 8 min and 10 minutes after the the injection of propofol or mixture of propofol and etomidate.

The following point-in-time will be recorded to calculated the period from the injection of propofol or mixture of propofol and etomidate: disappearance of eyelash reflex, injection of supplementary propofol or mixture of propofol and etomidate, awaking, obeying commands, discharge. Anesthesia time was defined as the period from disappearance of eyelash reflex to awaking.