Study Status: Not yet recruiting
Recruit Status: Unknown status
Study Type: Interventional
Official Title: Incidence of Gastroesophageal Reflux During LMA Application in Control and Spontaneous Ventilation
Brief Summary: Laryngeal mask airway is seldom used for control ventilation in America, while it is popular in China. The question is whether the incidence of gastroesophageal reflux in control ventilation is really higher than in spontaneous ventilation. So the investigators combine the third generation laryngeal mask and catheter-based Digitrapper ph-Z monitor system to evaluate the exact incidence of gastroesophageal reflux in these two groups.