Safety and efficacy of nitrous oxide for endoscopic ultrasound procedures that need irrigation

OBJECTIVE: Echo-endoscopes are much stiffer and thicker than regular endoscopes. During the procedure of endoscopic ultrasound (EUS) procedure, water irrigation is a very useful for imaging but very dangerous if the patient receive the procedure under anesthesia without intubation. In this study, we evaluated the safety and effectiveness of nitrous oxide (N(2)O) (≤70%) for EUS. METHODS: Among 4230 patients who underwent EUS from December 2012 to December 2013, 347 out patients who need irrigation during the procedure were enrolled and divided into Group A. Group A (N(2)O sedation group, n = 162) and Group B (no sedative group, n = 185). For Group A, patients received N(2)O by inhalation during the procedure. The mixture rate of N(2)O and O(2) was 45-65% and controlled by nurses according to individual effect. The cardiorespiratory functions, procedure duration, complications, and visual analog scale (VAS) of the patient and examiner satisfaction were compared. RESULTS: Both group had comparable diagnostic accuracy, but VAS of the patients who received N(2)O sedation was higher than that in Group B (7.5 vs. 4.5, P < 0.05) and the examiner procedural satisfaction ratings of Group A was also better than that of Group B (8.1 vs. 5.1, P < 0.05); Most patients in Group A reported willingness to reconsider N(2)O for a future EUS. No pulmonary aspiration occurred in this study. CONCLUSIONS: N(2)O for EUS is comfortable, safe and feasible, especially for the procedures that need irrigation.