Abstract: Objective This clinical study was conducted to investigate the effects of dexmedetomidine (DEX) combined with
propofol on vital signs and anaesthetic depth in patients. Methods Ninty patients with ASA 1-2 requiring painless colonoscopy
for colonic polyps resection were randomized to receive DEX 0.3 μg/kg (group D, n=45) followed by propofol 1 mg/kg or
propofol 2 mg/kg (group C, n=45), and according to the body activity and operation time, additional doses of propofol (0.2-0.5
mg/kg) were given. The full recovery time，operation time, consumed dose of propofol, mean arterial pressure(MAP), heart rate
(HR), hemoglobin oxygen saturation levels(SPO2) and NTI were recorded．Results The SPO2、recover time and the consumed
dose of propofol in group D were decreased compared to those in group C (P<0.01). The rate of the body activity in group D
was lower than that in group C (P<0.05). The NTI in group C was lower than that in group D (P<0.05). The HR and MAP were
similar in both groups. Conclusion Under Narcotrend monitoring, the value of DEX combined with low dose of propofol in
colonoscopy for colonic polyps resection is to reach more reasonable depth of anesthesia to reduce adverse responses and the
dose of propofol.