ABSTRACT
Objective To evaluate the effects of nitrous oxide inhalation on conscious sedation of patients during colonoscopy and analyze its risk factors. Methods From October 2016 to July 2017, a total of 154 patients undergoing colonoscopy were included in the study. The comfort level was rated using Modified Gloucester Comfort Scale ( MGCS). Factors affecting comfort level were analyzed by univariate analysis and multivariate Logistic regression, and then a comfort stratification predicting model was created. Results All 154 patients finished colonoscopy. The mean time of ideal anesthesia state was 195. 15 s. Among the 154 cases, 115 ( 74. 7%) were identified as comfort ( grade of MGCS from 1 to 3) and 39 (25. 3%) were rated as discomfort ( grade of MGCS from 4 to 5). Multivariate regression indicated that age ≥60 years ( P＝0. 000, OR＝1. 074, 95%CI: 1. 036-1. 114) and mild anxiety ( P＝0. 018, OR＝3. 338, 95%CI: 1. 227-9. 079) were associated with comfort level during colonoscopy.The established model with the age (X1) and mild anxiety (X2) was P＝eY/(1+eY), Y＝－3. 812+0. 071X1+1. 205X2(no anxiety was assigned 1, mild anxiety was assigned 2), and the area under the receiver operating characteristics curve was 0. 746 (95%CI: 0. 661-0. 830), which showed moderate predictive power of the final model. The model reached the highest predictive accuracy when the Yoden Index was 0. 838 with sensitivity of 50. 4% and specificity of 89. 7% for predicting comfort level of patients in conscious sedation status induced by nitrous oxide inhalation during colonoscopy. Conclusion Nitrous oxide can ease pain during colonoscopy, especially for patients over 60 years old and with anxiety. We can use it as an option according to actual circumstance in practice.