Analgesic Effect of Nitrous Oxide/Oxygen Mixture for Traumatic Pain in the Emergency Department: A Randomized, Double-Blind Study.

Background: Acute pain is the most common complaint in Emergency Department (ED) admissions, and options for analgesia are limited. Nitrous oxide/oxygen possesses many properties showing it may be an ideal analgesic in the ED. Objectives: The aim of this study is to evaluate the safety and analgesic effect of the fixed nitrous oxide/oxygen mixture for trauma patients in the ED. Methods: We enrolled 60 patients in this double-blind, randomized study. The treatment group received conventional pain treatment plus a mixture of 65% nitrous oxide/oxygen. The control group received the conventional pain treatment plus oxygen. Primary outcome was the reduction in pain intensity at 5 and 15 min after the start of intervention. Secondary outcomes include adverse events, physiological parameters, and satisfaction from both patients and health care professionals. Results: Initial pain scores for the nitrous oxide/oxygen group (6.0 [5.0-8.0]) and the oxygen group (6.75 [5.09.0]) were comparable (p = 0.57). The mean numerical rating scale scores at 5 min were 3.4 +/- 1.8 and 7.0 +/- 1.8 for nitrous oxide/oxygen and oxygen, respectively (p < 0.01). The mean pain intensity at 15 min in the treatment group was 3.0 +/- 1.9, compared with 6.3 +/- 2.2 in the control group (p < 0.01). Both patients' (8.0 [7.0-9.0] vs. 4.0 [2.0-6.0], p < 0.01) and physicians' (8.5 [8.0-9.0] vs. 4.0 [3.0-6.0], p < 0.01) satisfaction scores in the treatment group were significantly higher than the oxygen group. No serious adverse events were observed. Conclusions: This study gives supporting evidence for the safety and effectiveness of using self-administered nitrous oxide/oxygen mixture in the ED for moderate-to-severe traumatic pain. (C) 2019 Published by Elsevier Inc.