Comparison of Ultrasound-guided Location of Laryngeal Mask With Air Leakage Test

Inclusion Criteria:

• patients selected for this study must meet all of the following criterion:

  1. Age is between 17 to 65 years old;
  2. ASA (Amecican Society of Anesthesiology ) scores I-II;
  3. Actual weight is between 30 to 100 kilogram;
  4. Patients undergo selective supine operations under general anesthesia (laryngeal mask);
  5. Patients agree to participate in our study and sign Informed Consent Form

Exclusion Criteria:

• Patients cannot participate in this study if they have any of the following conditions:

  1. Airway stenosis, history of airway masses etc, whicn may cause obstruction to ventilation;
  2. Swelling of the neck caused by huge mass in the neck and history of neck surgery etc, which doesn't contribute to ultrasound observation;
  3. Stomach fullness, intestinal obstruction, gastroesophageal reflux disease etc, which may cause reflux aspiration.