Total 640 participants who are indicated to accept endoscopic examinations or procedures will be enrolled in this study. The participants will be divided into 2 groups according to the examination field, esophagogastroduodenoscopy group (320 participants) and colonoscope group (320 participants). The participants in each group will be divided into sedated endoscope subgroup and sedated and unsedated endoscope subgroup (each subgroup is inclusive of 160 participants). Carbon dioxide (CO2) or room air will be used randomly to insufflate the bowel lumen during the procedure in each subgroup.