title: Safety and efficacy of nitrous oxide for endoscopic ultrasound procedures that need irrigation.
abstract: 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 (N2O) (≤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 (N2O sedation group, n = 162) and Group B (no sedative group, n = 185). For Group A, patients received N2O by inhalation during the procedure. The mixture rate of N2O and O2 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 N2O 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 N2O for a future EUS. No pulmonary aspiration occurred in this study.
  
  
  CONCLUSIONS
  N2O for EUS is comfortable, safe and feasible, especially for the procedures that need irrigation.
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: S
authors.initials: S
authors.lastname: Sun
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: J
authors.initials: J
authors.lastname: Guo
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.affiliation: Endoscopy center, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: G
authors.initials: G
authors.lastname: Wang