Prospective cohort study to evaluate premedication with simethicone and N-acetylcysteine for upper diagnostic gastrointestinal endoscopy

Introduction: the use of premedication for upper gastroin-testinal endoscopy (UGE) is not widely established in west-ern countries. The primary aim of the study was to compare gastric visibility according to the total visibility score (TVS). The secondary aim was to assess complications, diagnostic yield, endoscopic procedure time, sedation dose and patient satisfaction.Methods: a single center prospective cohort study was performed of consecutive adults undergoing an UGE in the afternoon working shift. After completing enrolment in the control group, patients were administered 200 mg simethicone and 500 mg N-acetylcysteine diluted in 100 ml ofwater > 15 minutes before the procedure. All procedures were recorded and a single, blinded endoscopist evaluated the TVS after recruitment of both cohorts. Patient satis-faction was evaluated using the Spanish translation of the American Society of Gastrointestinal Endoscopy (ASGE) sat-isfaction questionnaire.Results: two hundred and five patients were included in the study, 103 females (50.2 %) with a median age of 54.8-years (IQR: 41.2-65.2). One hundred and four were enrolled to the control group and 101 to the intervention group. Patients receiving premedication presented a higher rate of ade-quate (74.3 % vs 45.2; difference 95 % CI: 16.3-41.9 %, p < 0.001) and excellent gastric visibility (23.8 % vs 7.7 %; dif-ference 95 % CI: 6.3-25.8 %, p = 0.002). Propofol dose was similar, although the median procedure time was lower in the group of no intervention (5 [IQR: 4-7] vs 6 minutes [IQR: 5-7]; p = 0.03). Procedure-related adverse events were similar, except that patient without premedication experi-enced more nausea episodes. Major and minor endoscopic findings and the satisfaction questionnaire showed no dif-ferences between both groups.Conclusion: patients receiving premedication with simethicone and N-acetylcysteine had a better gastric visibil-ity score, without any increase in adverse events or affecting the patients' satisfaction.