CO2 vs. Air Insufflation for Endoscopic Ultrasound

The insufflation of air in the viscera is indispensable during endoscopy. However, the distension of the bowel that follows is often the cause of abdominal discomfort. Carbon dioxide (CO2) has been widely used for insufflation in endoscopy. CO2 insufflation is demonstrated in the literature to cause lower abdominal discomfort as it is quickly reabsorbed by the body. Endoscopic ultrasonography (EUS) is a method in which you associate the endoscopic view and the ultrasound vision obtained from the inside of the viscera. The diagnostic accuracy of EUS is undermined by the visual artifacts caused by the presence of air between the probe and the organ to be studied. Although the use of CO2 is already widely applied by many endoscopists, there are no studies to date concerning the use of CO2 during EUS from the point of view of the abdominal discomfort related to the procedure and/or the quality of the images obtained. The main purpose of the study is to assess whether the insufflation of CO2 results in a reduction of discomfort of the patients undergoing EUS. The study design is observational because no randomization or other interventions are planned; participants will be assigned to either air or CO2 insufflation according to the endoscopic room equipment (one room is equipped with CO2 insufflation while another endoscopic room is equipped just with air insufflation) and the results of the two groups will be compared. Among the secondary goals the investigators want to evaluate whether insufflation of CO2 is associated with a reduction in the dose required for patients sedation. Finally, the investigators want to clarify whether the use of CO2 is able to produce less visual artifacts than air and thus improve the quality of EUS images.