20-70 year-old volunteers who hold legitimate licenses were recruited to have gastroscopy or colonoscopy under intravenous anesthesia with propofol

The dose of intravenous anesthesia drug and time was controlled by the anesthesiologist,endoscopists were responsible for gastroscopy or colonoscopy , nurses assisted endoscopists with biopsy.Each subject's initial dose of propofol were set at 2mg / kg, and were added properly by anesthesiologists additional according to the subjects' intraoperative sedation or surgical time.

before endoscopy using driving simulator to measure patients' driving ability as a baseline, in the same way, assessing patients' driving ability after 2h, 4h of the endoscopy.Driving simulation design scenes concluded low risk driving scene, medium risk driving scene and high risk driving scene.For low risk driving scene ,the observed indicators were average speed(m/s),average acceleration (m/s2), the average lane deviation (m), the maximum lane shift (m), the times of deviating from pathway .For medium risk driving scene ,the observed indicators were the minimum distance from overtaken vehicle, the times of overtaking intentions were observed in 80km/h and 40km/h speed limit.For high risk driving scene ,the observed indicators were maximum acceleration or deceleration, braking reaction time or accelerating reaction time.

before endoscopy using NCT to measure patients'cognitive function as a baseline, in the same way, assessing patients'cognitive function after 2h, 4h of the endoscopy.common methods for assessing patients' cognitive function include MoCA Rating Scale (Montreal assessment)、MMSE (Mini-Mental State score), due to the poor reproducibility,neither of them were selected. NCT is usually used to diagnose and assess the progress of subclinical hepatic encephalopathy, this test is simple, reproducible, widely used to assess psychomotor functions recovery after anesthesia . NCT includes part A and B, in order to simplify ,only part A was used for the study.NCT-A requires participants line 1-25 numbers which were randomly distributed on paper in ascending order in time as short as possible, and their finish time will be recorded.

collecting blood samples and separating blood plasma, using HPLC (High Performance Liquid Chromatography) to measure blood concentration of propofol after 2h,4h of endoscopy. Propofol blood concentration was measured by high performance liquid chromatography, which included high-performance liquid chromatography, C18 column, vortex mixer, high-speed centrifuges, reference reagents including propofol, thymol (internal standard) , methanol, acetonitrile, purified water, blank plasma. Measurement procedure can be summarized as the internal standard and plasma processing, the configuration of standard chromatographic conditions, HPLC analysis, the provision of the standard curve. The method detection limit was 0.5μg / ml, the scope of application of the linear concentration detection 0.5-4.0μg / ml. Determination of propofol blood concentration was done by researcher of Beijing Friendship Hospital drug testing experiment.