Objective To study the induction of nitrous oxide(N2 O)and to compare safety and effec-tiveness of conscious sedation by nitrous oxide inhalation and intravenous sedation with propofol for upper gas-trointestinal(UGI)endoscopy.Methods A total of 400 patients undergoing UGI endoscopy in our hospital from April 2013 to October 2013 were randomly assigned to two groups,N2 O inhalation group(n=200)and in-travenous propofol group(n=200).The systolic pressures,diastolic pressures,heart rates and oxygen satura-tion,onset time,procedure duration,degree of sedation,recovery time,length of hospital stay,complica-tions,satisfaction ratings of doctors and patients,and the number of patients willing to accept the examination again were analyzed.Results The mean time of ideal anesthesia state for N2 O was (3. 16 ±0. 65 )min and there was no difference between the male and female(3. 16 ±0. 71)min vs.(3. 16 ±0. 58)min,t=0. 006,P>0. 05).The mean concentration was (43. 68 ±5. 05 )%,which was higher in male than that in female [(45. 3 ±4. 99)% vs.(41. 46 ±4. 30)%,t=3. 042,P<0. 05].Compared with before,the systolic pres-
sures,diastolic pressures,heart rates and oxygen saturation of patients in the propofol group significantly re-duced during the procedure(P<0. 05),while the same measurements excluding oxygen saturation for those in the N2 O group significantly increased(P<0. 05 ).Compared with the propofol group,patients inhaling N2 O had significantly shorter recovery and hospital stay time,but a longer onset time and procedure duration(P<0. 05 ).Complications that occurred in some patients of propofol group included hyoxemia,hypotension,brady-cardia,while the major complication in the N2 O group was nausea.The satisfaction ratings of doctors or pa-tients and the number of patients willing to accept the examination again in N2 O group were smaller than those in propofol group(86 ±3. 7 vs.96 ±2. 6,87 ±2. 8 vs.98 ±1. 2,87%vs.99%,P<0. 05).Conclusion Both conscious sedation by N2 O inhalation and intravenous sedation with propofol are effective for diagnostic UGI en-doscopy,but the safety of the former is superior to the latter.The key to complete the conscious sedation by ni-trous oxide inhalation is to accurately identify the ideal anesthesia state of N2 O.It is significant to pay attention to the nine factors concerning safe and effective sedation during operation.

Objective To evaluate the efficacy of i-scan endoscopy in detecting small colorectal precancerous lesions.Methods A total of 127 patients were randomized into 2 groups to underwent conventional colonoscopy and i-scan endoscopy respectively.The findings were compared with pathologic examinations.Results A total of 84 lesions were detected by conventional endoscopy in 64 patients,while 147 lesions were found in 63 patients with high resolution detection only,which was increased to 259 with i-scan,including 102 flat lesions.With respect to histology,adenomatous lesions could be predicted with a high sensitivity (80％) and a high specificity ( 100％ ) by i-scan endoscopy.Conclusion More small colorectal lesions can be detected by i-scan endoscopy,which can distinguish neoplasm from non-neoplasm colorectal lesions.

ObjectiveTo evaluate digital chrome endoscopy (I-Scan) and confocal laser endomicroscopy (CLE) for diagnosis of Barrett esophagus (BE).MethodsFrom July 2010 to July 2011,a total of 878 outpatients who had upper gastrointestinal symptoms underwent routine endoscopy and I-Scan examination,screened patients with suspected Barrett's epithelial were further referred to CLE and endoscopy.The detection rate and image features of BE between routine endoscopy and I-Scan,and the diagnosis of BE between pathology and CLE,were compared respectively.ResultsSuspected BE was diagnosed in 46 patients (5.2％) by routine endoscopy,and in52 (5.9％) by I-Scan,and there was no significant difference in detection rate between 2 methods (x2 =0.533,P ＞ 0.05 ).The detection rate of paliform blood vessels between SCJ and GEJ was higher using I-Scan (35/52,67.3％ ) than routine endoscope (21/46,45.7％,P ＜0.05).A total of 19 suspected BE underwent CLE and biopsy,and BE was diagnosed by CLE with a sensitivity of 93％ and a specificity of 100％.ConclusionI-Scan is capable of identifying paliform blood vessels between SCJ and GEJ,and can improve the detection rate of suspected BE.CLE is able to provide in-vivo histological diagnosis of BE with a high sensitivity and specificity.

Objective To detect the mitochondrial microsatellite instability (mtMSI) and Helicobacter pylori (Hp) infection status in esophageal squamous cell carcinoma (ESCC),and to analyze their clinical significance in the diagnosis of ESCC.Methods The mtMSI and Hp infection status were examined by immunohistochemical SP method in 93 cases of ESCC and their normal control tissues.The relationship between Hp and mtMSI and their correlations with the clinicopathological features of ESCC were analyzed.Results The Hp positive rates of ESCC group and control group were 61.3％ (57/93) and 20.4％ (19/93) respectively,and there was statistically significant difference between the two groups (x2 =32.127,P ＜0.001).The mtMSI positive rates of ESCC group and control group were 34.4％ (32/93) and 0 (0/93) respectively,and there was statistically significant difference between the two groups (x2 =38.649,P ＜0.001).The Hp infection was correlated with tumor infiltrating degree (x2 =22.213,P ＜ 0.001) and lymph node metastasis (x2 =8.318,P =0.004),but was not correlated with gender (x2 =0.330,P =0.565),major axis of tumor (x2 =0.692,P =0.406),gross type (x2 =1.006,P =0.316),differentiated degree (x2 =0.665,P =0.415).The mtMSI was not correlated with gender (x2 =0.163,P =0.686),major axis of tumor (x2 =0.384,P =0.530),gross type (x2 =0.422,P =0.516),differentiated degree (x2 =0.213,P =0.645),infiltrating degree (x2 =0.001,P =0.979) or lymph node metastasis (x2 =0.039,P =0.843).The Hp infection was positively associated with mtMSI in ESCC (r =0.864,P =0.006).Conclusion The positive rates of Hp and mtMSI in ESCC are higher than those in normal tissues,and there is a close relationship between Hp and mtMSI.Hp is also associated with the progression of ESCC.

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.