Analgesic efficacy of nitrous oxide in adults in the emergency department: A meta-analysis of randomized controlled trials

Yihui Xing; Lingjun Zhou; Jianqiang Yu; Ziyang Wang; Zhiguo Ding; Chen Xie; Yuxiang Li; Fei Wang; Lu Tang

doi:10.1016/j.ajem.2022.03.028

Analgesic efficacy of nitrous oxide in adults in the emergency department: A meta-analysis of randomized controlled trials

Am J Emerg Med. 2022 Jun:56:92-99. doi: 10.1016/j.ajem.2022.03.028. Epub 2022 Mar 23.

Authors

Yihui Xing¹, Lingjun Zhou², Jianqiang Yu³, Ziyang Wang¹, Zhiguo Ding⁴, Chen Xie⁵, Yuxiang Li⁶, Fei Wang⁷, Lu Tang⁸

Affiliations

¹ School of Nursing, Weifang Medical University, Weifang, China; Department of Stomatology, the 960th hospital of People's Liberation Army of China (PLA), Jinan, China.
² School of Nursing, Naval Military Medical University, Shanghai, China.
³ Department of Pharmacology, College of Pharmacy, Ningxia Medical University, Yinchuan, China.
⁴ Department of Hepatopancreatobiliary Surgery, Qingdao Municipal Hospital, Qingdao, China.
⁵ Department of Orthopedics, the 960th hospital of PLA, Jinan, China.
⁶ Ningxia Medical University, Yinchuan, China.
⁷ Department of Anesthesiology, the 960th hospital of PLA, Jinan, China. Electronic address: wf_king_001@163.com.
⁸ Department of Stomatology, the 960th hospital of People's Liberation Army of China (PLA), Jinan, China. Electronic address: tanglu_office@163.com.

PMID: 35367685
DOI: 10.1016/j.ajem.2022.03.028

Abstract

Background: Nitrous oxide (N₂O) has a rapidly analgesic effect, but evidence regarding its role in managing pain in adults in the emergency department (ED) is conflicting. The purpose of this meta-analysis is to investigate the analgesic efficacy and safety of N₂O in adults in ED.

Methods: We systematically searched PubMed, the Cochrane Library, Embase, Web of science, China National Knowledge Infrastrusture (CNKI) and Wanfang Database up to August 10th, 2021. Randomized controlled trials (RCTs) were included if they compared N₂O/O₂ to placebo or other analgesic methods for management of pain in adults in ED or prehospital. The primary outcome was the analgesic efficacy of N₂O. Secondary outcomes included adverse events, satisfaction of patients and the duration of procedure.

Results: 14 RCTs with 1751 patients were included. Pooled analysis suggested that N₂O had better analgesia than placebo in the pain score (WMD = -3.00, 95% CI = -3.99 to -2.02, P < 0.00001, I² = 91%) and the number of patients with pain relief (OR = 6.18, 95% CI = 3.22 to 11.85, P < 0.00001, I² = 0%), while there were no significant difference in the pain score (WMD = 0.93, 95% CI = -1.09 to 2.95, P = 0.37, I² = 97%) or the number of patients with pain relief (OR = 0.07, 95% CI = 0.00 to 3.47, P = 0.18, I² = 86%) between the N₂O group and the other analgesic method group. Although N₂O did not increase nausea (OR = 1.52, 95% CI = 0.44 to 5.21, P = 0.50, I² = 54%) or satisfaction of patients (OR = 1.06, 95% CI = 0.16 to 7.18, P = 0.96, I² = 81%), it was associated with higher tendency of vomiting (OR = 6.50, 95% CI = 2.07 to 20.42, P = 0.001, I² = 29%) and dizziness (OR = 4.54, 95% CI = 2.27 to 9.09, P < 0.0001, I² = 26%), and shorter procedure time (WMD = -5.73 min, 95% CI = -10.14 min to -1.32 min, P = 0.01, I² = 98%).

Conclusions: The present meta-analysis suggested that N₂O could provide better analgesia than placebo and similar analgesia to other methods with more vomiting and dizziness in adults in ED.

Keywords: Analgesia; Emergency department; Meta-analysis; Nitrous oxide.

Publication types

Meta-Analysis
Review
Systematic Review

MeSH terms

Adult
Analgesics / therapeutic use
Dizziness* / chemically induced
Emergency Service, Hospital
Humans
Nitrous Oxide* / adverse effects
Pain / drug therapy
Randomized Controlled Trials as Topic
Vomiting / drug therapy

Substances

Analgesics
Nitrous Oxide