CO 2 vs. air insufflation in endoscopic ultrasonography: a prospective study

Background and study aims  Carbon dioxide (CO 2 ) is being increasingly used for insufflation during endoscopy for safety and better tolerance. The role of CO 2 during endoscopic ultrasonography (EUS) has not been studied yet. Our main aim was to compare the effects of CO 2 vs. air insufflation on abdominal discomfort in patients undergoing EUS. Our secondary outcomes were to ascertain the effects of CO 2 insufflation on image quality/visual artifacts and on the amount of sedation. Patients and methods  This was a prospective, controlled, single-blind, observational study. Abdominal discomfort was assessed before diagnostic EUS, and 1 and 3 hours post-procedure and recorded as a visual analogue scale. Image quality was also recorded as a 4-point scale from optimal to poor at four different scanning sites (esophagus, stomach, duodenal bulb and second portion). Results  A total of 198 patients were enrolled. We observed that CO 2 resulted in less abdominal discomfort than air insufflation that was statistically significant at 3 hours ( P  = 0.048) but not at 1 hour after EUS ( P  = 0.112), probably due to the ongoing effects of sedation at the latter stage. On the other hand, no differences were found in the dose of sedation administered in the two groups. Image quality was significantly better in the CO 2 group compared to the air group at all four different scanning sites ( P  < 0.01). Similarly, CO 2 correlated with less visual artifacts and need of suction ( P  < 0.01). Conclusions  Similarly to previous findings with other endoscopic procedures, EUS was associated with improved scores for abdominal discomfort with CO 2 rather than air insufflation. Moreover, overall EUS image quality was improved using CO 2 insufflation. Future studies are warranted to ascertain whether CO 2 insufflation should be regarded as the standard of care for diagnostic EUS.