Research in developing patient fasting guidelines was developed years ago. On a physiological basis, patients with a longer fasting time may have less residual gastric content and lower risk of pulmonary aspiration. The recent Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration of The American Society of Anesthesiologists (ASA) was published in March 2017. Current practice consists of 2-hour fasting period for clear oral fluid (including water, pulp-free juice and tea or coffee without milk), 4- hour fasting period for breast milk and 6-hour fasting period for non-human milk and solid food. However, there are only few supportive and suggestive scientific evidences. The purpose of this study is to evaluate the current clinical practice guidelines for preoperative fasting to enhance the quality of pediatric anesthesia care and promote patient safety.The investigators plan to enroll adults aged 18-60 years, who are scheduled for esophago-gastro-duodenoscopy (EGD), in order to study the effects of fasting time and the actual intragastric volume which may help us establish a comprehensive fasting guideline.

Research in developing patient NPO guidelines was developed years ago. On a physiological basis, patients with a longer fasting time may have less residual gastric content and lower risk of pulmonary aspiration. The recent Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration of The American Society of Anesthesiologists (ASA) was published in March 2017. Current practice consists of 2-hour fasting period for clear oral fluid (including water, pulp-free juice and tea or coffee without milk), 4- hour fasting period for breast milk and 6-hour fasting period for non-human milk and solid food. However, there are only few supportive (category A) and suggestive (category B) scientific evidences.

Since Maltby et al showed results of patient's safety in elective surgical patients who had clear oral fluid intake 2 hours before surgery in 1986, the published clinical evidence is still insufficient to address the relationship between pulmonary aspiration and fasting time . For breast milk, infant formula and solid food, the latest Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration in 2011 also follow previous suggestion of fasting time because of inadequate updated supportive clinical trials.

The purpose of this study is to evaluate the current clinical practice guidelines for preoperative fasting to enhance the quality of pediatric anesthesia care and promote patient safety. Andersson et al. reviewed 10,015 pediatric anesthesia charts retrospectively and found an incidence of 3 cases of pulmonary aspiration in 10,000 pediatric anesthesia patients who were allowed to drink clear liquid fluids until called to operative rooms . This approach promotes patient safety by minimizing a patient's dehydration status and reduced intraoperative hypotensive events. Furthermore, shortened fasting times also decreases patient irritability and improves parental satisfaction in preoperative experiences.

The investigators plan to enroll adults ages 18-60 years old, who are scheduled for esophago-gastro-duodenoscopy (EGD) at Siriraj hospital. This observational study will be conducted in 2 stages; (1) preoperative period (2) intraoperative period. Patients' demographic information will be collected along with NPO history including times, volume and type of fluid/ food intake in the preoperative period. Intragastric volume and pH from each patient's stomach at the beginning of EGD procedure will be measured in the intraoperative period.

The investigators believe that the information from this study will help us understand the effects of NPO time and the actual intragastric volume which may help establish a comprehensive NPO guideline.

Inclusion Criteria:

• Patients who are 18-60 years scheduled for EGD procedure
• Patient who willing to participate in this study

Exclusion Criteria:

• Patient who scheduled for emergent EGD procedures
• Patients with active upper GI bleeding
• Patients who received preoperative oral medication
• BMI > 30 kg/m2
• Patients with previous GI motility or acid-base pathology