Although proper sedation is mandatory for endoscopic procedures such as endoscopic submucosal dissection, the effects of sedation on ESD performance and complications have not been fully evaluated. In the investigators previous retrospective study, en bloc resection and complete resection rates, and procedure time could be improved by sedation with continuous propofol infusion with opioid administration by anesthesiologists. However, there are several limitations to the study including retrospective design. The investigators aimed to evaluate the relationship among sedation methods, satisfaction of endoscopists or patients, clinical outcomes, and complications after endoscopic submucosal dissection for gastric neoplasia.

Inclusion Criteria:

1. Age, between 20 and 80
2. Early gastric cancer or adenoma, which is indicated by endoscopic submucosal dissection
3. ECOG performance status 0 or 1
4. American Society of Anesthesiologist Physical Status 1, 2, or 3

Exclusion Criteria:

1. Previous subtotal gastrectomy
2. Previous gastrostomy
3. Repeated endoscopic submucosal dissection
4. Three or more synchronous lesions
5. Allergy to midazolam, propofol, fentanyl, or remifentanil
6. Pregnancy or breast milk feeding
7. Active infection
8. Significant cardiopulmonary disease
9. Active hepatitis or severe hepatic dysfunction
10. Severe renal dysfunction
11. Severe bone marrow dysfunction
12. Severe neurologic or psychotic disorder