To observe the safety and effectiveness of transnasal administration of dexmedetomidine (DEX) in elderly patients undergoing painless colonoscopy.

120 elderly patients who underwent painless colonoscopy in Changzhou Second People’ s Hospital from November 2018 to May 2020 were selected as the research objects. They were randomly divided into control group (group C), low-dose DEX (group D₁), medium-dose DEX (group D₂) and high-dose DEX (group D₃), with 30 cases in each group. After routine ECG monitoring, intranasal administration of 1.5 ml saline for the patients in group C, while intranasal administration of 1.0, 1.5 and 2.0 μg/kg DEX respectively for the patients in group D₁, D₂, D₃. Enteroscopy could be performed after 1.5 mg/kg propofol was administrated, and 0.5 mg/kgpropofol was supplement for somatic reaction, such as body movement, eye opening, and coughing. The mean arterial blood pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO₂) before the intranasal administration of DEX (T₀), 15 min after intranasal administration of DEX (T₁), just the time of the endoscopy (T₂), just the time of splenic flexure (T₃), and record the BIS value and total amount of propofol medication after withdrawal (T₄) were observed. Recovery time, the number of somatic reactions and adverse reactions (vomit, hypotension and bradycardia) were recorded.

(1) Comparison within groups: MAP, HR and BIS values in four groups at T₁-T₄ were lower than those at T₀ (all P<0.05); The SpO₂ level in group C at T₁-T₂ was significantly lower than that in the same group at T₀ (P<0.05), and no significant difference was found in the SpO₂ level in group D₁, D₂ and D₃ at each time point. (2) Comparison among groups: At T₀, there were no significant differences in MAP, HR, SpO₂ and BIS values among the four groups. At T₁-T₄, there were statistically significant differences in MAP, HR, SpO₂ and BIS values among the four groups (F=5.323-49.369, all P<0.01). (3) Pairwise comparison among groups: at T₁-T₄, HR in D₃ group was significantly lower than that in the other three groups (P<0.05). At T₂-T₄, MAP in group D₁, D₂ and D₃ was significantly lower than that in group C (P<0.05), and the change range of group D₂ was the least; BIS values in group D₁, D₂ and D₃ were lower than those in group C at T₁ and T₃, and BIS values at T₂ and T₄ were higher than those in group C (P<0.05), with the most significant change in group D₃. During T₁-T₄, SpO₂ in group D₂ and D₃ was significantly higher than that in group C (P<0.05), and the change range in group D₃ was the most significant. There were significant differences in the amount of propofol (F=28.922, P<0.001), time of recovery (H=24.452, P<0.001) and sedation score (Z=113.500, P<0.001) among the four groups. The dosage of propofol, recovery time and sedation score in group D₂ and D₃ were significantly better than those in group C (P<0.05). The incidence of hypotension in group C was higher than that in the other three groups, and the incidence of bradycardia in group D₃ was higher than that in the other three groups (P<0.05). The overall efficacy of group D₂ was better than that of group D₃.

For elderly patients with painless colonoscopy examination, compared with the simple intravenous application of propofol, preoperative15 min in the combination of 1.5 μg/kg dose DEX by nasal drug delivery, sedative effect is better, more stable hemodynamics in patients with simple operation, low incidence of adverse reactions, as a safe and ideal anesthetic scheme, is worth of popularization and application in clinical.