Evaluation of antihyperalgesic and analgesic effects of 35% nitrous oxide when combined with remifentanil: A randomised phase 1 trial in volunteers.

Abstract

BACKGROUND:

Remifentanil is an effective drug in peri-operative pain therapy, but it can also induce and aggravate hyperalgesia. Supplemental administration of N2O may help to reduce remifentanil-induced hyperalgesia.

OBJECTIVE:

To evaluate the effect of 35 and 50% N2O on hyperalgesia and pain after remifentanil infusion.

DESIGN:

Single site, phase 1, double-blind, placebo-controlled, randomised crossover study.

SETTING:

University Hospital, Germany from January 2012 to April 2012.

PARTICIPANTS:

Twenty-one healthy male volunteers.

INTERVENTIONS:

Transcutaneous electrical stimulation induced spontaneous acute pain and stable areas of hyperalgesia. Each volunteer underwent the following four sessions in a randomised order: 50 to 50% N2-O2 and intravenous (i.v.) 0.9% saline infusion (placebo); 50 to 50% N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (remifentanil); 35 to 15 to 50% N2O-N2-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (tested drug) and 50 to 50% N2O-O2 and i.v. remifentanil infusion at 0.1 μg kg-1 min-1 (gas active control). Gas mixtures were inhaled for 60 min; i.v. drugs were administered for 30 min.

MAIN OUTCOME MEASURES:

Areas of pin-prick hyperalgesia, areas of touch-evoked allodynia and pain intensity on a visual analogue scale were assessed repeatedly for 160 min.

RESULTS:

Data from 20 volunteers were analysed. There were significant treatment and treatment-by-time effects regarding areas of hyperalgesia (P < 0.001). After the treatment period, the area of hyperalgesia was significantly reduced (P < 0.001) in the tested drug and in the gas active control (30.6 ± 9.25 and 24.4 ± 7.3 cm2, respectively) compared with remifentanil (51.0 ± 17.0 cm2). There was also a significant difference between the gas active control and the tested drug sessions (P < 0.001). For the area of allodynia and pain rating, results were consistent with the results for hyperalgesia.

CONCLUSIONS:

Administration of 35% N2O significantly reduced hyperalgesia, allodynia and pain intensity induced after remifentanil. It might therefore be suitable in peri-operative pain relief characterised by hyperalgesia and allodynia, such as postoperative pain, and may help to reduce opioid demand.

TRIAL REGISTRATION:

EudraCT-No.: 2011-000966-37.

• Authors: Andreas Wehrfritz, Marcus Bauer, Nathalie Noel, Juan Fernando Ramirez-Gil, Harald Ihmsen, Johannes Prottengeier, Jürgen Schüttler, Baptiste Bessiere
• Journal: European journal of anaesthesiology (Eur J Anaesthesiol) Vol. 38 Issue 12 Pg. 1230-1241 (12 01 2021) ISSN: 1365-2346 [Electronic] England
• PMID: 34735395 (Publication Type: Clinical Trial, Phase I, Journal Article, Randomized Controlled Trial)
• Copyright: Copyright © 2021 European Society of Anaesthesiology and Intensive Care. Unauthorized reproduction of this article is prohibited.

Chemical References

• Analgesics, Opioid
• Piperidines
• Nitrous Oxide
• Remifentanil

Topics

• Analgesics, Opioid
• Double-Blind Method
• Healthy Volunteers
• Humans
• Hyperalgesia (chemically induced, diagnosis, drug therapy)
• Male
• Nitrous Oxide
• Pain, Postoperative
• Piperidines (adverse effects)
• Remifentanil