The study is designed to explore and compare the efficacy and safety of etomidate and propofol with or without analgesic for painless gastroscopy, and to provide more reliant support for implementation and promotion of comfort care.

To widely implement painless gastroscopy is required by diagnose and treatment with gastroscopy due to the large number and significant suffering of the patients. Also, development and exploration of anesthesiology will be bound to prompt the development and exploration of painless gastroscopy. However, the anesthesia risk of painless gastroscopy are usually higher than that of general anesthesia performed in operating room due to the condition, monitoring and equipments as well as the staffing for its implementation. Thus, the finding of a safe and convenient approach for general anesthesia will have a profound impact on a full promotion and implementation of comfortable care.

Etomidate, with the main advantage of little effect on circulatory and respiratory systems, and the features of rapid onset and metabolism, may be helpful to guarantee the safety of painless diagnosis and treatment, thus appropriate for the procedure with short duration of anesthesia. However, there is controversy regarding whether analgesic should be used in combination, as well as how to given the combined regimen.

Inclusion Criteria:

• Patients scheduled for painless gastroscopy
• 18-80 year old
• 18 H2 ≤ weight ≤ 35 H2 (H indicates height)
• American Society of Anesthesiologists (ASA) physical status class 1-3
• The duration of surgery is ≤ 60 min ( duration of surgery was defined as the interval time from insert to withdraw of catheter)
• Without liver, kidney and heart disease history
• No previous history of abnormal recovery of anesthesia in surgery

Exclusion Criteria:

• Patients whom do not wish to perform painless gastroscopy or participate in the study
• Patients with medical history of severe heart, lung, liver, kidney or metabolic disease
• Patients with abnormal ECG presented as heart rate 50 < beat/min
• Patients who suffered from acute inflammation of respiratory tract within the past 2 weeks and did not be cured of it before participating in the study
• Hypertension patient with preoperative blood pressure > 180/90 mmHg; hypotension patients with preoperative blood pressure < 90/60 mmHg;
• Patients with neuromuscular disease, mental disorders
• Hemoglobin is less than 90 g/L
• Patients with suspected abuse of Anesthesia and Analgesia
• Patients who were predicted to have or had previous difficult airway ( difficult airway is defined as the clinical situation in which a conventionally trained anesthesiologist experiences three failures of intubation)
• Patients with known emulsion or opioid allergy
• Patients who will be noncompliant or unable to communicate
• Patients who received long-term treatment with hormone or had history of adrenocortical suppression
• Patients received coadministration of other sedative, analgesic ( including injection, oral or usage of relevant Chinese patent medicine) before, during or 15 min after the procedure
• Patients who appeared nausea and vomit, dizziness
• Patients with sever diabetes mellitus, hyperkaliemia or significant electrolyte disturbances