Although propofol is widely used as an induction agent for a general anesthesia, it can induce a profound hypotension, which leads to the hypo-perfusion of end organs and eventually increases morbidities. Theoretically, applying Trendelenburg position (head down and leg up position) increases cardiac preloads and cardiac outputs. However, in past researches, changing to Trendelenburg position alone is not enough and does not prevent propofol induced hypotension. Previous studies proved that leg wrapping effectively prevent hypotension after neuraxial anesthesia during Cesarean section. The leg wrapping prevents hypotension by increasing vascular resistance of lower extremities. The investigators made a hypothesis that applying both Trendelenburg position and leg wrapping prevent propofol induced hypotension more effectively than either applying Trendelenburg position only or taking no preventive measures.

** Study procedure

1. check baseline blood pressure ( systolic, diastolic, mean) and heart rate.
2. apply pre-defined measures to each group(arm) ( summarized in arms and interventions section )
3. induction using propofol 2mg/kg
4. After bispectral index (BIS) goes below 60 & patient become unconsciousness, inject rocuronium 0.6mg/kg
5. intubate patient between 3 and 4 minutes after propofol injection
6. measure blood pressure ( systolic, diastolic, mean ) & heart rate at 1,2,3,4,5 minutes after propofol injection
7. phenylephrine injection if hypotension develops

Inclusion Criteria:

• American Society of Anesthesiologist's physiologic status class 1, 2, and 3.
• under general anesthesia

Exclusion Criteria:

• severe cardiac/pulmonary/liver/renal disease
• BMI > 30 kg/m2
• known or risk factor of increased intraocular pressure or intracranial pressure
• uncontrolled hypertension
• high risk for propofol allergy
• allergies to medications related to anesthesia
• mechanical difficulties with leg wrapping ( wound on legs, devices on legs )
• emergent operation
• high risk of gastric aspiration ( gastrointestinal obstruction, short nil per os(NPO) time )
• patient wearing elastic stocking for therapeutic purpose