Relationship Between Optimal Laryngeal Mask Airway Cuff Volume and Physical Examination of Head and Neck

"1. measurement of head and neck~ * Ht,Wt,BMI, neck circumference above a thyroid cartilage, mandible circumference( from the lower part of earlobe-mandible angle-mentum-mandible angle to the lower part of earlobe), neck length (mastoid tip\~sternal notch), modified mallampati classification under sitting position, thyromental distance.~2. laryngeal mask airway insertion and measuring cuff pressure by pressure transducer~ * \# 4.0 for female, #5.0 for male~ * initial cuff volume(air) : maximum volume recommended by the manufacturer~ * check pressure : if it exceed 60cmH20, we will remove air until 60cmH20~ * remove air until gas leak occured around the cuff under airway pressure 15cmH20, fresh gas flow 6liters/min. Check the volume and pressure just before leakage occured."