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Please use this identifier to cite or link to this item: http://hdl.handle.net/11055/555
Title: Chronic postsurgical pain in the Evaluation of Nitrous Oxide in the Gas Mixture for Anaesthesia (ENIGMA)-II trial.
Authors: Chan, M T V
Peyton, P J
Myles, P S
Leslie, K
Buckley, N
Kasza, J
Paech, M J
Beattie, W S
Sessler, D I
Forbes, A
Wallace, S
Chen, Y
Tian, Y
Wu, W K K
Issue Date: Dec-2016
Citation: British journal of anaesthesia 2016-12; 117(6): 801-811
Abstract: Previous animal and clinical studies showed that nitrous oxide may produce long-term analgesia. The aim of this study was to evaluate the effect of nitrous oxide in preventing chronic postsurgical pain. We also explored whether methylenetetrahydrofolate reductase gene polymorphisms (1298A>C, 667C>T) would enhance nitrous oxide analgesia. We conducted a telephone interview at 12 months after surgery on 2924 (41.1%) patients enrolled in the Evaluation of Nitrous Oxide in the Gas Mixture for Anaesthesia-II trial. Pain at the wound site was recorded using the modified brief pain inventory and the neuropathic pain questionnaire. General health status was measured using the EQ-5D questionnaire. Genotyping was performed in a subset of 674 Asian patients in Hong Kong. At 12 months after surgery, 356 (12.2%) patients reported chronic postsurgical pain at the wound site and 112 (3.8%) patients had severe pain and required regular analgesic interventions. Nitrous oxide did not affect the rate of chronic postsurgical pain (11.8% nitrous oxide group; 12.5% no nitrous oxide group), relative risk (95% confidence intervals): 0.94 (0.75-1.17), P=0.57. However, in a planned subgroup analysis, nitrous oxide reduced the risk of chronic postsurgical pain in Asian patients, relative risk (95% confidence intervals): 0.70 (0.50-0.98), P=0.031. Patients who were homozygous for either gene polymorphism and who received nitrous oxide during surgery were less likely to report chronic postsurgical pain. Nitrous oxide administration had no impact on chronic postsurgical pain, but benefits may still be possible in Asian patients and patients with variants in methylenetetrahydrofolate reductase gene. NCT00430989.
URI: http://hdl.handle.net/11055/555
DOI: 10.1093/bja/aew338
PubMed URL: https://www.ncbi.nlm.nih.gov/pubmed/27956679
Journal Title: British journal of anaesthesia
Type: Journal Article
Appears in Collections:Scholarly and Clinical

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