Air Insufflation Group Research Articles

Clinical value of sigmoid colon water exchange colonoscopy: a prospective randomized clinical trial

This prospective randomized controlled trial investigated the clinical value of sigmoid colon water exchange (SWE) colonoscopy by comparing it with air insufflation (AI) colonoscopy in terms of the patient’s pain score, insertion time, and screening quality. Consecutive patients who underwent colonoscopy without sedation were randomized into an AI group (n = 267) or an SWE group (n = 255). Patient characteristics, history of abdominal or pelvic surgery, maximum pain score, insertion time, cecal intubation rate, polyp detection rate, and the need for maneuvers were recorded. There was no significant between-group difference in insertion time, cecal intubation rate, assisted maneuvers (abdominal pressure, changing patients’ position), or polyp detection rate (P > 0.05). The mean maximum pain score was significantly lower in the SWE group than in the AI group. (3.57 ± 2.01 vs. 4.69 ± 1.83, P < 0.001). For patients with a history of abdominal or pelvic surgery and those who were overweight (body mass index > 24), the maximum pain scores were lower in the SWE group than in the AI group (3.67 ± 1.95 vs. 4.88 ± 1.80, P < 0.001; 3.40 ± 1.96 vs. 4.79 ± 1.97, P < 0.001, respectively). SWE colonoscopy can significantly reduce abdominal pain with non-inferior screening quality and does not increase insertion time.Trial registration number: ChiCTR2200059057 (date April 23, 2022).

A111 CLINICAL AND PATHOLOGICAL OUTCOMES BETWEEN WATER EXCHANGE AND AIR INSUFFLATION USING NON-SEDATED EXTENDED FLEXIBLE SIGMOIDOSCOPY FOR AVERAGE RISK COLORECTAL CANCER SCREENING: PRELIMINARY FINDINGS FROM A RANDOMIZED CONTROL TRIAL

Abstract Background Colorectal cancer (CRC) is Canada's third most common cancer type and represents approximately 11% of all cancer deaths. While sedated colonoscopy or flexible sigmoidoscopy (FS) continues to be considered for CRC screening, these modalities have limitations and risks. Another unevaluated screening modality, known as an extended FS (EFS), attempts to capitalize on the benefits of a FS while minimizing the risks involved with a sedated colonoscopy. EFS provides a scope-based examination up to the splenic flexure and then attempts to examine beyond, often to the point of the caecum. Providing the option for EFS may produce improvements in the patient experience and performance, which may improve the feasibility of using scope-based screening more broadly in screening programs. Purpose To determine the extent non-sedated EFS using the water exchange method (WE) is associated with a complete colon examination compared to the traditional air insufflation (AI) method using CO2 in an average-risk screening population. Method This randomized control trial included 90 non-sedated participants, screened by trained general surgery and gastroenterology clinicians at Kelowna General Hospital, British Columbia, Canada, using two different scope insufflation techniques, WE and AI. The primary outcome of interest was the cecal intubation rates (CIR), while secondary outcomes included the adenoma detection rate (ADR) and reported pain scores. Other metrics, such as patient satisfaction rates, sessile serrated adenoma detection rates (SSADR), and serrated lesion detection rates (SLDR) were also recorded. Result(s) The demographic characteristics between the WE and AI groups were statistically similar, with the mean age of participants being 58 and 57, respectively. During the study period, four endoscopists performed the EFS. There were higher initial satisfaction rates in the WE group vs the AI (95% vs 77%, satisfaction of ≥ 9/10 p = 0.028). CIR and ADR were similar between the WE and AI group (CIR = 93% vs 91%, p = 0.710), (ADR = 40% vs 34%, p = 0.660). The SSADR and SLDR were also similar between the WE and AI group (SSADR = 21% vs 14%, p = 0.408), (SLDR = 42% vs 36%, p = 0.528). Conclusion(s) EFS without sedation using either technique exceeds quality benchmarks recommended for sedated screening colonoscopy while maintaining adequate patient safety and comfort. The WE method optimizes a patient's overall experience making a strategy of average risk colorectal cancer screening with non-sedated WE EFS feasible. Please acknowledge all funding agencies by checking the applicable boxes below CAG, Other Please indicate your source of funding; Kelowna General Hospital, Interior Health Disclosure of Interest None Declared

Transient End-Tidal Carbon Dioxide Elevation During Pediatric Upper Endoscopy With Carbon Dioxide Insufflation: Is It True Hypercapnia?

Endoscopic insufflation, long performed using air, is being replaced by carbon dioxide (CO2) at many pediatric centers, despite limited published data on its use in children. We have previously demonstrated that CO2 use during esophagogastroduodenoscopy (EGD) in non-intubated children is associated with transient elevations of end-tidal CO2 (EtCO2). This observation raised concerns about possible CO2 inhalation and systemic absorption. Here, we investigate this concern by concurrently measuring both EtCO2 and transcutaneous CO2 (tCO2) during upper endoscopic procedures in children. To determine if elevations in EtCO2 levels seen in non-intubated children undergoing CO2 insufflation during EGD are associated with elevated systemic CO2 levels. Double-blinded, prospective, randomized clinical trial. Children were randomized 1:1 to receive either CO2 or air for endoscopic insufflation. EtCO2 was sampled with a CO2-sampling nasal cannula and tCO2 was monitored using the Radiometer transcutaneous monitoring device. Fifty nine patients were enrolled; 30 patients in the CO2 insufflation group and 29 in the air group. All patients underwent a procedure involving an EGD. Transient elevations in EtCO2 (defined as >60 mmHg) were observed only in the CO2 insufflation group. This contrasted with the similar elevations of tCO2 between the CO2 and air insufflation groups. None of these events were of clinically significant magnitude or duration. This study demonstrates that the observed transient elevations in EtCO2 seen during EGD in non-intubated children receiving CO2 insufflation are most likely measurements of eructated CO2 without evidence of excessive systemic absorption of CO2.

A prospective randomized controlled trial of the safety and efficacy of carbon dioxide insufflation compared with room air insufflation during gastric endoscopic submucosal dissection.

Carbon dioxide (CO2 ) insufflation during gastric endoscopic submucosal dissection (GESD) under sedation can be used instead of room air insufflation. Appropriate monitoring of the partial pressure of CO2 during GESD is necessary due to the impaired respiration. The aim of this study was to assess the safety and efficacy of CO2 insufflation during GESD compared with conventional room air insufflation. Patients with a gastric epithelial neoplasm or early gastric cancer were enrolled. A total of 76 consecutive patients were randomly assigned to the CO2 insufflation group (CO2 group) or the room air insufflation group (air group). The primary outcome was the mean difference of end-tidal CO2 (EtCO2 ) between two groups. The upper bound of the 95% CI for the mean EtCO2 difference between the two groups before the procedure and at 15, 30 and 45 min after insufflation met the criteria for noninferiority. In a subgroup analysis of patients 70years and older, the mean difference of EtCO2 was not significantly different between two groups. However, the air group received more analgesics than the CO2 group after the procedure (67.6% vs 35.1%, P=0.005). In addition, in terms of improvement of abdominal pain or bowel gas after 24h of GESD, CO2 group showed better results than air group (both P<0.05). CO2 insufflation during GESD is as safe as using room air, and patients, including elderly patients, receiving CO2 achieve more rapid relief of abdominal pain and intra-abdominal residual gas during and after the procedure.

S212 Comparing Polyp Detection Rate Between Water Exchange and Air Insufflation by a Computer-aided Detection Algorithm: An Analysis of Withdrawal Phase Videos from a Randomized Controlled Trial

Introduction: Water exchange (WE) improves polyp (PDR) and adenoma detection rate (ADR) compared with air insufflation [GIE 2021;93:1411], but still misses polyps due to human limitations [JCG 2021, in press]. A computer-aided detection (CADe) algorithm can overcome human omissions, but is limited by false positives (FPs) [Lancet Gastroenterol & Hepatol 2019;4:71], which might be reduced by salvage-cleaning effect provided by insertion WE [Tzu-Chi Med J 2021;33:108]. We hypothesized that the strengths of CADe and WE can complement the weaknesses of each other. Their combination can enhance PDR and ADR and reduce false positive rate (FPR). Methods: We used a locally developed convolutional neural network with YOLOv4 to build a CADe model. Images of polyps (n=15961) were divided in 80% and 20% for training and testing. Prior to real-time application, we validated the model in detecting polyps, using edited and coded withdrawal phase videos of the right colon from a RCT comparing right colon adenoma detection between WE and air insufflation. The polyps detected by the CADe were confirmed by the consensus of 2 blinded reviewers (experienced endoscopists). We also developed a computer-aided diagnosis (CADx) model based on YOLOv4 to characterize the detected polyps as adenomas or not. The primary and secondary outcomes were PDR and the FPR, respectively. Results: A total of 245 coded videos of colonoscopies inserted with WE (n=123) or air insufflation (n=122) were analyzed. CADe achieved significantly higher PDR in the WE group (61.8%) than in the air insufflation group (40.2%), P=0.0009. CADe also had significantly higher additional PDR in the WE group (30.1% vs 12.3%, P=0.001). The CADx assessed ADR was significantly higher in the WE group than that in the air insufflation group (46.3% vs 30.3%, P=0.018), after the detected polyps were characterized by the CADx. (Table a) The mean numbers of FPs related to feces [1.78 (1.67) vs 2.09 (2.09), P=0.007] and bubbles [0.53 (0.89) vs 1.25 (2.45), P=0.001] were significantly lower in the WE group than in the air insufflation group. (Table b). Conclusion: The data confirmed the hypothesis that the strengths of CADe and WE complemented the weaknesses of each other, enhanced PDR and ADR and reduced FPR. The locally developed CADe and CADx are validated for polyp detection and adenoma assignment for real-time application. Furthermore, WE provides an optimal platform for the computer-assisted algorithms.Table 1.: ADR, adenoma detection rate; All the percentages calculated according to respective total number of patients for each group; PDR, polyp detection rate; Total numbers of polyps were based on those found by the performing endoscopist plus those detected by the CADe; Proportion of additional polyps found by CADe equals numbers of additional polyp (adenomas) found by CADe divided by total numbers of polyps (adenomas). Others: ileocecal valve, cecum, polypectomy site, suction marks and drug pills. † Mann-Whitney test; ††Fisher exact test.

S175 Water Exchange Increased Advanced Adenoma Detection in the Ascending and Proximal Colon As Compared to Air Insufflation

Introduction: Randomized control trials (RCT) showed significant increase in adenoma detection rate (ADR) with water exchange (WE) compared with usual air or CO2 insufflation colonoscopy. Advanced adenoma detection rate (AADR) is a validated surrogate marker for colorectal cancer risk (GI Endosc Clin N Am 2002;12:1). There was limited data of the impact of WE on AADR, probably due to the small sample sizes of RCT. Pooled analysis of 6 published RCT suggested that WE significantly increased overall ADR and overall AADR of the entire colon (JCG 2020;54:212). The impact of WE on ADR and AADR in the ascending colon, where interval cancers tend to cluster (AJG 2014;109:1375), is unknown. We test the hypothesis that WE increased AADR by aggregating the data of 4 RCTs conducted by our group in Chiayi and Hualien, Taiwan. Methods: Data from 4 RCTs (NCT01894191, NCT02737514, NCT01535326, and NCT01699399) comparing WE and air insufflation were aggregated. The demographic characteristics, procedure related outcomes, ADR and AADR were tabulated. Results: Both the WE and air insufflation group included 503 patients. Table 1 shows that the demographic characteristics were similar between the two groups. WE had significantly shorter withdrawal time [mean (SD), 13.0 (6.8) vs 12.6 (8.5), P=0.017], and higher Boston Bowel Preparation Scale scores than the air insufflation group. The ratio of aspirate water volume to infused water volume at cecum (107%) indicated proper implementation of WE (Table 1). The WE group had significantly higher overall ADR (46.4% vs 54.9%, P=0.008), with the difference mainly occurring in the ascending colon (23.0% vs 30.9%, P=0.005) than the air insufflation group. The WE group had significantly higher AADR in the ascending (4.6% vs 7.8%, P=0.048) and proximal (6.4% vs 10.5%, P=0.023) colon. The overall AADR (16.3% vs 19.7%) was numerically higher in the WE group (P=0.189, possibly a type II error) (Table 1). Conclusion: Interval cancers tend to occur in the right and proximal colon. The beneficial effect for WE to increase right and proximal colon AADR (a validated surrogate marker for colorectal cancer risk) might hold the potential to reduce the occurrence of interval cancers. The aggregated data of 4 RCTs showed WE had significantly higher AADR in the right colon and proximal colon as compared to air insufflation. Future studies to evaluate the impact of WE on the occurrence of interval cancers are justified.Table 1.: †Chi-square test; ††Fisher’s exact test; *Mann-Whitney test; ADR, adenoma detection rate; AADR, advanced adenoma detection rate; BBPS, Boston Bowel Preparation Scale. Advanced adenoma was defined as an adenoma with a diameter of ≥ 10 mm, significant villous features (> 25%), or high-grade dysplasia. The ascending colon included the cecum, ascending colon and hepatic flexure. The proximal colon included the cecum, ascending and transverse colon.

Comparison of Water Immersion Versus Air Insufflation Colonoscopy Under Various Bowel Preparation Conditions.

To investigate the differences between water immersion (WI) and air insufflation (AI) for colonoscopy under various bowel preparation conditions. In this study, 526 outpatients were randomly assigned to two groups, namely a WI group (n = 263) and an AI group (n = 263). During the procedure, the quality of bowel preparation, abdominal pain score, cecal intubation rate (CIR), adenoma detection rate (ADR), the intubation times, and other indicators were recorded. After reaching the cecum, each group of patients was subdivided into one of four grades (excellent, good, fair, and poor) according to the quality of bowel preparation. Under various bowel preparation conditions, the pain scores of the AI group were higher than those of the WI group (P < .05), but there was no significant difference between the two groups in CIR (P > .05). For the WI group compared with the AI group, the cecal intubation time (CIT) was prolonged under good bowel preparation (P = .045) and fair bowel preparation (P < .001). No significant differences were observed between the two groups on ADR in all patients (P = .476). Compared with AI colonoscopy, WI colonoscopy can decrease colonoscopy-related pain in patients for unsedated colonoscopy under various bowel preparation conditions, but there is no significant difference in CIR. WI colonoscopy requires longer CIT in patients with good and fair bowel preparation conditions. WI colonoscopy does not significantly increase ADR.

Insufflation of Carbon Dioxide versus Air During Colonoscopy Among Pediatric Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Background/Aims:Carbon dioxide is increasingly used in insufflation during colonoscopy in adult patients; however, air insufflation remains the primary practice among pediatric gastroenterologists. This systematic review and meta-analysis aims to evaluate insufflation using CO2 versus air in colonoscopies in pediatric patients. Methods:Individualized search strategies were performed using MEDLINE, Cochrane Library, EMBASE, and LILACS databases following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Cochrane working methodology. Randomized control trials (RCTs) were selected for the present meta-analysis. Pooled proportions were calculated for outcomes including procedure time and abdominal pain immediately and 24 hours post-procedure. Results:The initial search yielded 644 records, of which five RCTs with a total of 358 patients (CO2: n=178 versus air: n=180) were included in the final analysis. The procedure time was not different between the CO2 and air insufflation groups (mean difference, 10.84; 95% confidence interval [CI], -2.55 to 24.22; p=0.11). Abdominal pain immediately post-procedure was significantly lower in the CO2 group (risk difference [RD], -0.15; 95% CI; -0.26 to -0.03; p=0.01) while abdominal pain at 24 hours post-procedure was similar (RD, -0.05; 95% CI; -0.11 to 0.01; p=0.11). Conclusions:Based on this systematic review and meta-analysis of RCT data, CO2 insufflation reduced abdominal pain immediately following the procedure, while pain was similar at 24 hours post-procedure. These results suggest that CO2 is a preferred insufflation technique when performing colonoscopy in pediatric patients.

551 Comparing Advanced Adenoma Detection Rate of Water Exchange, Cap, and Endocuff Colonoscopy: Pooled Data of Randomized Controlled Trials With Air Insufflation as the Common Comparator

INTRODUCTION: Advanced adenomas, defined as adenomas ≥10mm, significant villous features (&gt;25%), or high-grade dysplasia, are important targets for colorectal cancer screening. They represent the subpopulation of adenomas that are most likely to progress into carcinoma and are associated with increased risk for future CRC incidence. Advanced adenoma detection rate (AADR) is therefore an important measure in assessing new screening methods. Water exchange (WE) colonoscopy has been shown to improve AADR consistently while modern accessories, such as cap and endocuff, have variable impacts on AADR. We assessed the impact on AADR between WE, cap and Endocuff by indirect comparison with standard air insufflation (AI) as the common comparator. METHODS: A literature search was done to identify all relevant RCTs comparing WE, Cap and Endocuff with AI colonoscopy published since 2000 as full text in English and included AADR among the outcomes. EMBASE, Medline, SCOPUS, and Cochrane Library were searched systematically using the following terms in their titles, abstracts, or keyword lists: colonoscopy, and water exchange, cap, or Endocuff. Two investigators screened the articles manually and separately. The results were compared, and a discussion was held with a third investigator to resolve any discrepancies. RESULTS: 1,453 articles resulted from keywords search and were manually screened. 14 RCTs met criteria and were included in the analysis. A total of 12,085 subjects underwent AI, WE, cap (CC) or Endocuff-assisted (EC) colonoscopy. AADR of WE, CC, and EC were compared against AI. Table 1 shows that WE significantly increases AADR compared to AI (8.1% vs 6.0%, P = 0.0001, Fisher exact test). CC does not significantly change AADR compared to AI (8.7% vs 8.2%, P = 0.585). No significant difference in AADR exists between EC and AI (16.6% vs 17.0%, P = 0.815). AADR in WE, CC, and EC as a percentage change of AI are 35.0%, 6.1% and -2.4%, respectively. While WE significantly increases AADR, CC and EC do not significantly impact AADR. Compared to CC and EC, WE has a higher percentage increase in AADR (vs the common comparator of AI). This may be related to the low AADR in the AI group in the WE trials. CONCLUSION: WE appears to significantly increase AADR, especially in patient cohort with lower AADR. Cap and Endocuff does not have significant impact on AADR.

525 Impact of Water Exchange, Cap and Endocuff on Adenoma Detection Rate: An Indirect Comparison With Air Insufflation as the Common Comparator

INTRODUCTION: Adenoma detection rate (ADR) is an important quality indicator for colonoscopy. Interval cancer (IC) is associated with low ADR. Every 1% increase in ADR is associated with a 3% and 5% reduction of the risk of IC and fatal IC, respectively. Water exchange (WE) colonoscopy is considered the best insertion method for improving ADR when compared with water immersion and air insufflation (AI). Attachment devices such as cap and Endocuff also improve ADR. We assessed the effectiveness of improving ADR between WE, cap and Endocuff colonoscopy by indirect comparison with AI as the common comparator. METHODS: A literature search was done to identify all relevant RCTs comparing WE, cap and Endocuff with AI colonoscopy published since 2000 as full text in English and including ADR among the outcomes. EMBASE, Medline, SCOPUS, and Cochrane Library were searched systematically for all RCTs that included the following terms in their titles, abstracts, or keyword lists: colonoscopy, and water exchange, cap, or Endocuff. Two investigators screened the articles manually and separately. The results were compared; and a discussion was held with a third investigator to resolve any discrepancies. RESULTS: A total of 1,453 articles resulted from initial keywords search. 37 articles were identified based on titles and abstracts alone. After thorough review of full texts, and discussion between the investigators, 21 RCTs were included in the analysis. A total of 16,572 subjects underwent AI, WE, cap (CC) or Endocuff (EC) colonoscopy. ADR of WE, CC, and EC were compared to AI. Table 1 shows that there is a significant difference in ADR between AI and WE (24.2%, 30.8%, P = 0.0001). ADR in AI and EC were significantly different (41.7%, 48.0%, P = 0.0001). No significant difference in ADR exists between AI and CC, (36.8%, 36.6%, P = 0.92). ADR as a percentage change of AI in WE, EC and CC were 27.4%, 15.1% and -0.42%, respectively. We found that WE and EC significantly improved ADR while CC does not significantly change ADR. Compared to EC and CC, WE has a higher percentage increase in ADR. This greater increase in ADR by WE may be related to the low ADR in the AI group. CONCLUSION: The impact of the study method in enhancing overall ADR is more prominent with the WE method, especially in patient cohort with lower ADR.

Feasibility of sedation on demand in Taiwan using water exchange and air insufflation: A randomized controlled trial.

Completion of colonoscopy without sedation eliminates sedation cost and complications. Reported in the United States and Europe, on-demand sedation is not routine practice in Taiwan. Water exchange (WE), characterized by infusion and nearly complete removal of infused water during insertion, reduces insertion pain compared to air insufflation (AI) during colonoscopy. We evaluated the feasibility of on-demand sedation in Taiwan. In a randomized controlled trial of WE vs AI colonoscopy, we also aimed to determine if WE augmented the implementation by reducing insertion pain and decreasing sedation requirement. This prospective patient-blinded study randomized patients to AI or WE (75 patients/group) to aid insertion. The primary outcome was the proportion of patients completing without sedation. In the AI and WE groups, 76.0% and 93.3% (P=0.006) completed without need for sedation, respectively. The WE group had lower insertion pain score (mean [SD]) (4.0 [2.9] vs 2.1 [2.6], P<0.001), lower doses of propofol (25.7 [52.7] mg vs 9.1 [35.6] mg, P=0.012), and less time in the recovery room (3.4 [7.4] vs 1.5 [5.5], P=0.027) than the AI group. Patient satisfaction scores and willingness to repeat if needed in the future were similar. On-demand sedation was feasible in Taiwan. The completion rate without sedation was high in patients (76.0% with standard AI) open to the option (no prior intent to receive the standard of full or minimal sedation). WE augmented the implementation by reducing insertion pain and decreasing sedation requirement without adversely affecting patient satisfaction or willingness to repeat.

Carbon dioxide insufflation reduces residual gas in the gastrointestinal tract following colorectal endoscopic submucosal dissection.

Quantitative examinations evaluating the effects of CO2 insufflation on residual gas in the gastrointestinal tract following colorectal endoscopic submucosal dissection (ESD) are lacking. The present study aimed to assess whether CO2 insufflation could decrease the amount of residual gas in the gastrointestinal tract following ESD in patients with colorectal neoplasms. Computed tomography (CT) was used to objectively examine whether CO2 insufflation during colorectal ESD reduced residual gas levels in the gastrointestinal tract following ESD. A total of 83 patients who underwent colorectal ESD between January and December 2009 at Gifu University Hospital (Gifu, Japan) were enrolled. Following exclusion of 17 patients with chronic pulmonary dysfunction, 66 patients were randomized into a CO2 insufflation group (n=34) and an air insufflation group (n=32). The level of residual gas and the presence of transmural and free-air leaks following ESD were evaluated in both groups using CT. Transcutaneous CO2 tension (PtcCO2) and ESD-related complications were also compared between the groups. CT measurements of the major and minor axes of the cecal lumen, and of the terminal ileum diameter, indicated the level of residual gas following ESD to be significantly reduced in the CO2 insufflation group compared with the air insufflation group (P<0.001). Neither the incidences of ESD-related complications, including post-procedure hemorrhage and air leak, nor the abnormalities in vital signs differed between the groups. No significant between-group differences were identified in the baseline and peak PtcCO2 levels during ESD or in the median PtcCO2 following ESD. In conclusion, CO2 insufflation during colorectal ESD was effective in reducing residual gas in the gastrointestinal tract following ESD.

Effect of Carbon Dioxide Insufflation on Adenoma Detection Rate in Comparison to Air Insufflation: A Meta-Analysis

Introduction: Colonoscopy is the gold standard test for prevention of colorectal adenocarcinoma by identifying and removal of adenomas, the pre-cancerous lesion. One of the most common complications from colonoscopy is postprocedural abdominal pain and discomfort due to air insufflation during the procedure. Carbon dioxide(CO2) insufflation has been shown to reduce post procedure crampy abdomen pain due to easy dissolvability in blood and rapid elimination. However the effect of CO2 insufflation on adenoma detection rate(ADR) remained unclear, with studies showing positive and negative effect on ADR. We aimed to do a meta-analysis to identify the effect of CO2 insufflation on ADR when compared to air insufflation by pooling results of individual studies. Methods: Comprehensive literature search was performed in EMBASE, Scopus, Pubmed, Cochrane databases from 1946 to May 31, 2017 to identify potential articles. MeSH headings included in the search included adenoma detection rate, colonoscopy, carbon dioxide insuffl ation. All references from the identified articles were further searched to find more articles. Abstracts published from major gastroenterology meetings were also searched up to May 2017. Studies were included if they compared ADR on cohorts of patients undergoing colonoscopy with CO2 insufflation and air insufflation and had no major differences in baseline characteristics. Odds ratio of ADR was compared between the 2 techniques. Statistics were done using Revman version 5.3 Results: A total of 202 articles were identified from the search strategy and from articles identified through references and abstracts. A total of 4 studies met the inclusion criteria and out of which 3 were published manuscripts and one was abstract. Total number of patients included in the analysis was 3466(2140 in CO2 group, 1326 in air insufflation group). There was no statistically significant difference in ADR between the 2 groups - 1.11 [0.95-1.31](Image 1). However there was significant heterogeneity between the tests, possibly due to low number of studies that qualified for inclusion. Conclusion: CO2 insufflation appears to be non-inferior for adenoma detection when compared to air insufflation. With no disadvantage on ADR with using CO2 insufflation, endoscopy units should adapt the change from air to CO2 insufflation to improve patient experience. Future large randomized trial should be done to study if CO2 insufflation improves ADR when comparing air insufflation.Figure

Effect of Water Immersion versus Air Insufflation on Gastroenterology Trainee Insertion Times With the Full Spectrum Endoscopy (FUSE) Non-variable Stiffness Colonoscope

Introduction: Use of water immersion (WI) during colonoscopy is thought to facilitate colonoscope insertion by straightening the sigmoid, minimizing loop formation and decreasing colonic redundancy. This technique has the potential to facilitate insertion for trainees especially when using colonoscopes without variable stiffness. However, WI is often underutilized due to perceptions that it may result in increased insertion and/or procedure times when compared to standard air insufflation (AI) or carbon dioxide (CO2) insufflation. The primary aim of our study is to compare colonoscope insertion times of 2nd and 3rd year gastroenterology trainees using AI and WI. Methods: We retrospectively reviewed colonoscopies performed by 2nd and 3rd year gastroenterology trainees with a non-variable stiffness colonoscope (Full-Spectrum Endoscopy, FUSE, EndoChoice) at New York Presbyterian/Allen Pavilion Hospital from 10/29/2015 to 5/24/2017. Beginning 12/15/2016, all colonoscopies with the FUSE system were exclusively performed using WI. During WI, sterile water was infused via irrigation pump without air or CO2 until at least past the sigmoid but often to completion. All specimens were obtained upon withdrawal. For comparison, AI procedures were chosen where no specimens had been obtained to ensure no effect on insertion time. External stiffening devices were not available for use. Patient demographics, indication for procedure (screening/surveillance, diagnostic), preparation, completion, and insertion times were documented and compared for AI and WI techniques. Results: There were 32 AI and 31 WI cases performed by 8 gastroenterology trainees. In the AI group 25 (78.1%) procedures were performed on women with a mean age of 62.2 years compared to the WI group where 15 (48.3%) were performed on women with a mean age 55.2 years. All patients had adequate preparation and complete exams. Patients with colonic resections were excluded. The mean colonoscope insertion time for the AI group was 13.8 minutes (range: 3.5 - 44.6, median 12.1) compared to 11.3 minutes (range: 4.0 - 32.5, median 10.3) for the WI group, p=0.2. Conclusion: There is no significant difference in colonoscope insertion times for 2nd and 3rd year gastroenterology trainees using AI and WI and FUSE non-variable stiffness colonoscopes. There is a trend towards decreased insertion times with WI. Further studies are need to evaluate the potential benefit of WI on endoscopic education for trainees.

Comparison of Adenoma Detection Rate Between Water Exchange Colonoscopy and Air Insufflation Colonoscopy: A Meta-Analysis

Introduction: Colonoscopy is the preferred procedure for prevention of colorectal cancer by detecting its precursor lesion, adenomas. However, several studies have reported an adenoma miss rate of 10-25% despite technical improvements in endoscopic techniques. Adenoma detection rate(ADR) is an important quality indicator for colonoscopies. Water exchange(WE)technique has been shown to reduce postprocedural discomfort and also helpful in difficult colonoscopy. However its impact on ADR when compared to air insufflation(AI) has yield mixed results. We aimed to do a meta-analysis to answer this question Methods: Comprehensive literature search was performed in EMBASE, Scopus, Pubmed, Cochrane databases from 1946 to May 31, 2017 to identify potential articles. MeSH headings included in the search included adenoma detection rate, colonoscopy, water exchange, air insufflation. All references from the identified articles were further searched to find more articles. Studies were included if they reported ADR on cohorts of patients undergoing colonoscopy with WE and AI techniques. Odds ratio of ADR and cecal intubation time were compared between WE and AI. Statistical analysis were done using Revman version 5.3. Results: A total of 156 articles were identified from the search strategy and from articles identified through references and abstracts. A total of 11 studies met the inclusion criteria. Total number of patients included in the analysis was 6976(3483 in WE group, 3493 in AI group). WE technique improved ADR when compared to AI technique and the results were statistically significant(1.41; 95% CI 1.26-1.58) (image 1). There was no heterogeneity between the studies (I2=0%). Six studies reported cecal intubation time and the use of WE increased the cecal intubation time by an average of 3.42 minutes (95% CI 1.63-5.21) or 3 minutes 25 seconds.(image 2). Conclusion: WE technique is superior to AI technique with respect to adenoma detection rate during colonoscopy. However the disadvantage of WE in terms of longer cecal intubation time should be taken into account in interpretation of these results. WE also improves patient experience by reducing postprocedural abdominal discomfort and should be considered at least in patients with difficult colonoscopies.Figure: Adenoma detection rate.Figure: Mean difference of cecal intubation time.

CO2 insufflation versus air insufflation for endoscopic submucosal dissection: A meta-analysis of randomized controlled trials.

BackgroundCarbon dioxide (CO2) insufflation is increasingly used for endoscopic submucosal dissection (ESD) owing to the faster absorption of CO2 as compared to that of air. Studies comparing CO2 insufflation and air insufflation have reported conflicting results.ObjectivesThis meta-analysis is aimed to assess the efficacy and safety of use of CO2 insufflation for ESD.MethodsClinical trials of CO2 insufflation versus air insufflation for ESD were searched in PubMed, Embase, the Cochrane Library and Chinese Biomedical Literature Database. We performed a meta-analysis of all randomized controlled trials (RCTs).ResultsEleven studies which compared the use of CO2 insufflation and air insufflation, with a combined study population of 1026 patients, were included in the meta-analysis (n = 506 for CO2 insufflation; n = 522 for air insufflation). Abdominal pain and VAS scores at 6h and 24h post-procedure in the CO2 insufflation group were significantly lower than those in the air insufflation group, but not at 1h and 3h after ESD. The percentage of patients who experienced pain 1h and 24h post-procedure was obviously decreased. Use of CO2 insufflation was associated with lower VAS scores for abdominal distention at 1h after ESD, but not at 24h after ESD. However, no significant differences were observed with respect to postoperative transcutaneous partial pressure carbon dioxide (PtcCO2), arterial blood carbon dioxide partial pressure (PaCO2), oxygen saturation (SpO2%), abdominal circumference, hospital stay, white blood cell (WBC) counts, C-Reactive protein (CRP) level, dosage of sedatives used, incidence of dysphagia and other complications.ConclusionUse of CO2 insufflation for ESD was safe and effective with regard to abdominal discomfort, procedure time, and the residual gas volume. However, there appeared no significant differences with respect to other parameters namely, PtcCO2, PaCO2, SpO2%, abdominal circumference, hospital stay, sedation dosage, complications, WBC, CRP, and dysphagia.

Water infusion versus air insufflation during the insertion phase of unsedated colonoscopy: a single-center single blind randomized controlled trial

Objective To compare effects of warm water infusion and air insufflation on patient tolerance and satisfaction during the insertion phase of unsedated colonoscopy. Methods In a single-center, prospective, single blind randomized trial, patients were randomly assigned to three groups (water infusion group, air insufflation group, or hybrid method group) during the insertion phase of colonoscopy. Main outcome measurements included insertion time, cecal intubation rate, adenoma detection rate, the rate of position change, the rate of abdominal compression, intraoperative pain and distension VAS scores, postoperative pain and distension VAS scores. Results A total of 180 cases were enrolled, 60 in each group. Patients in water infusion group and hybrid method group required less abdominal compression or position change, longer insertion time, reported lower intraoperative pain and distension VAS scores than air insufflation group during the insertion phase of colonoscopy. There were no significant differences in cecal intubation rates, adenoma detection rates, postoperative pain and distension or VAS scores among three groups. Conclusion Water infusion significantly decreases patient abdominal pain and distension during the insertion phase of colonoscopy without affecting cecal intubation rate and adenoma detection rate. Key words: Colonoscopy; Self tolerance; Air insufflation; Water infusion

Carbon Dioxide Insufflation During Screening Colonoscopy Is Associated with Higher Serrated Adenoma Detection Rate: A Single-Center Retrospective Analysis

Introduction: Carbon dioxide insufflation (CO2 I) has been associated with faster cecal intubation, reduced post-procedural pain and improved patient satisfaction when compared to air insufflation (AI). The effect of CO2 I on serrated adenoma detection rate (SADR) remains unclear.The goals of this study are: (1) Compare SADR in patients undergoing screening colonoscopy with CO2 I versus AI and (2) to identify predictors of SADR in our cohort.Table 1: Baseline CharacteristicsTable 2: Predictors of Serrated Adenoma Detection Rate (SADR)Methods: Single-center retrospective cohort study of patients undergoing elective screening colonoscopy at an academic medical center during a 2-year period (2012-2014). Prior to January 2013, all colonoscopies were performed with AI. Data were retrieved from a prospective colonoscopy database and through chart review. Age, gender, trainee involvement, scope withdrawal time, total procedure time, body mass index (BMI), bowel preparation, ASA score, type of sedation, and type of insufflation were included in the univariate (UVA) and multivariate analysis (MVA) to identify predictors of SADR. SADR was defined as the detection of at least one histologically confirmed traditional serrated adenoma or sessile serrated adenoma during colonoscopy. Results: Screening colonoscopy was performed in 2083 patients (46% male; 59.0 ± 8.7 mean age years) by 25 endoscopists during the study period. Bowel preparation was rated good to excellent in 1492 (71.6%) patients. Cecal intubation rate was 98.4% with a mean scope withdrawal time of 9.6 ± 6.6 minutes. Trainees were involved in 861 (41.3%) of the colonoscopies. SADR was calculated to be 4.76% in the CO2 I group compared to 1.26% in the AI group (p = 0.0002). Overall, SADR was 3.7% in the cohort. Both UVA (OR = 3.91, CI = 1.78-8.20, p = 0.0003) and MVA (OR = 9.52, CI = 3.05-30.3, p = 0.0001) showed that CO2 I was associated with higher SADR when compared to AI. Higher BMI and longer scope withdrawal times were also associated with increased SADR on both UVA and MVA. Conclusion: CO2 I was associated with a significantly higher SADR when compared to AI during screening colonoscopy. Furthermore, higher BMI and longer scope withdrawal time were also independently predictive of increased SADR. Future randomized controlled studies are needed to further corroborate these preliminary findings and the effect of CO2 I on SADR during screening colonoscopy.

Evaluation of abdominal circumference and salivary amylase activities after unsedated colonoscopy using carbon dioxide and air insufflations

To assess and compare abdominal distention and stress in unsedated colonoscopy using carbon dioxide (CO2 ) and air insufflations. Two hundred and five patients underwent colonoscopic examinations without sedation using either CO2 or air insufflation. Abdominal circumference and salivary amylase (sAMY) activities before and 0 and 15 min after colonoscopy were measured by a nurse who was blinded to the grouping of the patients. In all, 102 and 103 patients were randomly recruited in the CO2 and air insufflation groups, respectively. sAMY activities before and 0 and 15 min after colonoscopy were not significantly different between the two groups. Abdominal circumference measured immediately and 15 min after colonoscopy was significantly smaller in CO2 insufflation group than in the air insufflation group (81.2 cm vs 84.0 cm, and 79.7 cm vs 83.6 cm, respectively; P <0.05). The increasing ratio of abdominal circumference immediately after colonoscopy was not significantly different between the two groups; however, the ratio at 15 min after colonoscopy using CO2 insufflation was significantly lower than that in the air insufflation group (1.007 vs 1.028, P <0.001). sAMY activities after unsedated colonoscopy using CO2 insufflation were not improved; however, CO2 insufflation decreases abdominal circumference after colonoscopy compared with air insufflation.

Efficacy of carbon dioxide insufflation during gastric endoscopic submucosal dissection: a randomized, double-blind, controlled, prospective study

Endoscopic submucosal dissection (ESD) is commonly performed under air insufflation and is often accompanied by abdominal discomfort. CO2 is absorbed more rapidly by the body than is air; however, the use of CO2 insufflation in ESD remains controversial. This randomized, double-blind, controlled, prospective study was designed to assess the efficacy of CO2 versus air insufflation in gastric ESD. Between May 2012 and August 2014, a total of 110 patients with gastric tumors were randomly assigned to the CO2 insufflation (CO2 group, n = 54) or air insufflation group (air group, n = 56). Abdominal pain after ESD was chronologically recorded via visual analog scale (VAS) scores. Secondary outcome measurements were adverse events, abdominal circumference, amount of sedatives prescribed, and use of analgesics. Neither the baseline patient characteristics nor the mean procedural time differed between the groups. The VAS score for abdominal pain was 35.2 in the CO2 insufflation group versus 48.5 in the air insufflation group 1 hour after ESD (P = .026), 27.8 versus 42.5 three hours after ESD (P = .007), 18.4 versus 34.8 six hours after ESD (P = .001), and 9.2 versus 21.9 one day after ESD (P < .001). Changes in abdominal circumference, the amounts of sedative drugs taken, and the adverse events did not differ between the groups. However, the air insufflation group required more analgesics than did the CO2 insufflation group (CO2 group, 22.0% [11/50]; air group, 42.3% [22/52]; P = .028). CO2 insufflation during gastric ESD significantly reduced abdominal pain and analgesic usage compared with air insufflation. ( NCT01579071.)