The difference of oropharyngeal leak pressure and sealing pressure between new supraglottic airway devices.

In this clinical study, investigators want to discuss the issue that oropharyngeal leak pressure and sealing condition with different SGA including air-Q、i-gel、LMA-supreme、AMBU auragain 、ProSeal LMA and other new SGAs.

In the perioperative period, investigators documented respiratory function data including oropharyngeal leak pressure and peak airway pressure in these randomly selected SGA. Oropharyngeal leak pressure was measured by closing the expiratory valve of the circle system at fixed O2 flow 3L/min and noting the airway pressure at which the dial on a calibrated aneroid manometer reached equilibrium.

investigators wanted to compared the respiratory function between air-Q、i-gel、LMA-supreme、AMBU auragain、ProSeal LMA and other new SGAs during surgery and postoperative care unit.

Inclusion criteria:

1. 20-80 years old.
2. ASA physical status I or II .
3. Without major organ dysfunction like heart, liver, brain, lung, kidney function failure.

Exclusion criteria:

1. BMI> 35 kg/m2.
2. Risk of aspiration(NPO clear water> 2 hours, solid foods > 8 hours).
3. Difficult airway like head and neck tumor or airway tumor.
4. Limited mouth opening (<2cm).
5. major organ dysfunction including heart, liver, brain, lung, kidney function failure.
6. Major surgery including open heart surgery, laparotomy general surgery, open chest surgery.

All general anesthesia patients who use SGA.