A Meta-Analysis Of Efficacy And Safety Of Carbon Dioxide Insufflation During Colonoscopy

ObjectiveThe object of this study was to evaluate systematically the effectiveness and safety of carbon dioxide insufflation?CI?forcolonoscopycomparedwith airinsufflation?AI?,provide reference for clinical gas usage ofcolonoscopy.MethodsDatabases including Pub Med,EMBASE,the Cochrane Library,the Science Citation Index,CNKI,Wangfang database,VIP databaseand important meeting abstracts were searchedfrom inception to January 2017 and 31studies were enrolled into thisanalysis.The two investigators evaluated quality of the eligible trials by using Jadad Score evaluate evidence grade and extracted necessary data.the details of the trial design,characteristics ofthe subjects,results of the studies were reviewed andanalyzed by usingthe Rev Man 5.3 statistical package.Random effects model was used tocalculate the effect size of both binary and continuous data.Heterogeneity among the outcome variables of these trials was determined by the Cochran Q statistic and I₂ indexand funnel plot.Result1.31 randomized controlled trials?RCTs?comprising 4929 patients?2473 were CI and 2456 were AI?were included in the study.The overall quality of included studies are high,and the evidence grade is from moderate to high level.According to the statistical heterogeneity of the studies,a random effects model or a fixed effect model was usud to meta analysis.2.There were no significant difference in cecal intubation rate OR =1.03?95%CI:0.74-1.42,P=0.88,I² = 0%?,cecal intubation time SMD=-0.22?95%CI:-0.48-0.03,P=0.08,I² =42%?,total examination time SMD=-0.2?95%CI:-0.63-0.23,P=0.36,I² =0%?,adverse event rate OR =OR =0.39?95%CI:0.09-1.68,P=0.21,I² = 0%?and gas usage SMD= 0.89?95%CI:-2.21-4,P=0.57,I² =42%?in both colonic insufflation techniques.2.Our meta-analysis indicated that CI showeda significant decrease in patients with procedural pain events OR =0.43?95%CI:0.32-0.59,P<0.00001,I²= 62%?,pain scores SMD=-0.85?95%CI :-1.57 —-0.13,P=0.02,I 2 = 98%?and also postproceduralpain events at early stage OR =0.17?95%CI:0.12-0.25,P<0.00001,I²= 65%?scores SMD=-1.28?95%CI:-1.80—-0.77,P<0.00001,I² =96%?,medium stage events OR =0.29?95%CI:0.18-0.47,P<0.00001,I²= 63%?scores SMD=-0.62?95%CI:-0.98—-0.25,P=0.0009,I² = 93%?,late stage events OR =0.48?95%CI:0.29-0.79,P=0.004,I 2 =50%?.but the scores did not show significant difference SMD=-0.07?95%CI:-0.17-0.03,P=0.18,I² = 27%?.Compared with air,CO₂ insufflation was associated with less procedural bleach bloating SMD=-1.25?95%CI:-1.98—-0.53,P<0.0007,I² =87%?and also postprocedural bloating at early stage SMD=-1.94?95%CI:-2.56—-1.31,P<0.00001,I² =81%?.Also CI showed a trend towards reducingflatulencepost procedurally OR =0.04?95%CI:0.01-0.11,P<0.00001,I² =0%?and medium stage OR =0.03?95%CI:0.00-0.32,P=0.003,I² = 73%?.4.Comparable effects were noted for procedural ETCO2 OR =0.2?95%CI:0.03-1.17,P=0.07,I²=0%?and postprocedural ETCO2 OR =0.2?95%CI:0.01-4.17,P=0.30,I² Not applicable?.There were no significant differences in safety betweenthe two methods.ConclusionInsufflation with CO₂ in colonoscopycould decrease abdominal discomfort during andfollowing the procedure.There is no difference in the cecal/ileal intubation rateand time and total examination time between the 2 methods.CO₂ retention with CO₂ insufflation has no adverse effect on patients.