Original Contributions| Volume 57, ISSUE 4, P444-452, October 2019

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

Published:September 09, 2019DOI:



      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.


      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.


      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.


      Initial pain scores for the nitrous oxide/oxygen group (6.0 [5.0–8.0]) and the oxygen group (6.75 [5.0–9.0]) 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.


      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.


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