the frequency of tussis, nausea and vomiting, and/or body movements observed at the insertion of the endoscope into the pharyngeal cavity or within 5 min of endoscope insertion.

The patients are selected according to their inclusion and exclusion criteria for diagnostic upper GI endoscopy and informed consent. The patients will be divided into the four groups: P group (single administration of propofol), P + S group (administration of propofol and sufentanil in combination), P + K group (administration of propofol and esketamine in combination), and P + L group (administration of propofol and lidocaine in combination) (N = 100 per group). Baseline information will be collected and recorded before the operation. Anaesthetic drugs will be prepared by the nurses and anaesthetists on the day of the operation as follows: 0.9% normal saline (20 mL) for the P group, 0.5 μg/mL sufentanil (20 mL) for the P + S group, 1.5 mg/mL esketamine (20 mL) for the P + K group, and 10 mg/mL lidocaine (20 mL) for the P + L group. Before entering the operating room, the patients will be given lidocaine defoamer for gargling to open the upper limb vein and 5 mL/min Lactate Ringer solution. After entering the room, the patients will wear masks to inhale high-flow oxygen, and their vital signs will be monitored and recorded as Tire. Analgesic drugs (diluted to 20 mL according to different concentrations) prepared by the nurses will be slowly injected into their veins 5 min before examination for 30 s (the dose was calculated using the formula: the injected drug dose (ml) = the weight of the patient (kg)/10"; 1.5 mg/kg propofol will be intravenously administrated. . Multiple-dose administration is acceptable according to the state of the patient. The endoscope will be inserted when the eyelash reflex disappeared (sedation depth grade: deep sedation). Blood pressure will be recorded after every 3 min from the beginning of the examination, and HR, SpO2, and RR will be recorded simultaneously. The frequency and degree of tussis, nausea, and vomiting and/or body movements at endoscope insertion or within 5 min of insertion will be monitored. In case of any abnormalities, they should be described in detail, and appropriate doses of propofol should be added until the endoscope exits the teeth pad. During endoscopy, 2-4 mL of propofol should be added under the conditions of extended operation time, accelerated breathing, and elevated blood pressure and heart rate to maintain deep sedation. The patients will be transferred to a recovery room after the operation, and their vital signs will be recorded after every 5 min until the patients met the standard of leaving the hospital (Steward score ≥ 4) before discharge

Inclusion Criteria

• undergoing diagnostic upper GI endoscopy under deep propofol sedation
• >18 year old
• meeting the classification I-III of American Society of Anesthesiologists (ASA)
• getting written informed consent

Exclusion Criteria:

• allergic reaction to planned medication
• gravis myasthenia
• history of psychological problems or psychiatric disease
• morbid obesity/obstructive sleep apnea
• acute upper respiratory infections
• asthma at acute stage
• history of unregulated or malignant hypertension
• history of significant ischemic heart disease or severe arrhythmia
• severe liver or kidney dysfunction or coagulation disorders
• acute upper GI haemorrhage with shock
• severe anaemia
• GI obstruction with gastric retention
• seizure disorders
• long-term history of sedative and analgesic drug use
• increased intracranial pressure.