Nitrous Oxide for Early Analgesia in the Emergency Setting: A Randomized, Double‐blind Multicenter Prehospital Trial

Abstract

Objectives: Although 50% nitrous oxide (N 2 O) and oxygen is a widely used treatment, its efficacy had never been evaluated in the prehospital setting. The objective of this study was to demonstrate the efficacy of premixed N 2 O and oxygen in patients with out-of-hospital moderate traumatic acute pain.Methods: This prospective, randomized, multicenter, double-blind trial enrolled patients with acute moderate pain (numeric rating scale [NRS] score between 4 and 6 out of 10) caused by trauma. Patients were assigned to receive either 50/50 N 2 O and oxygen 9 L/min (N 2 O group) or medical air (MA) 9 L/min (MA group), in ambulances from two nurse-staffed fire department centers. After the first 15 minutes, every patient received N 2 O and oxygen. The primary endpoint was pain relief at 15 minutes (T15), defined as a NRS 3 of 10. The NRS was measured every 5 minutes. Secondary endpoints were treatment safety and adverse events, time to analgesia, and patient and investigator satisfaction with analgesia.Results: Sixty patients were included with no differences between groups in age (median = 34 years, interquartile range [IQR] = 23 to 53 years), sex (37 males, 66%), and initial median NRS of 6 (IQR = 5 to 6). At T15, 67% of the patients in the N 2 O group had an NRS score of 3 or lower versus 27% of those in the MA group (delta = 40%, 95% confidence interval [CI] = 17% to 63%; p < 0.001). The median pain scores were lower in the N 2 O group at T15, 2 (IQR = 1 to 4) versus 5 (IQR = 3 to 6). There was a difference at 5 minutes that persisted at all subsequent time points. Four patients (one in the N 2 O group) experienced adverse events (nausea) during the protocol. 1 For a number of years, many rescue organizations throughout the world, including some employing caregivers not trained as emergency medical technicians, have made use of 50% nitrous oxide (N 2 O) and oxygen analgesia.2 There has been limited clinical evidence for the efficacy of this form of analgesia. N 2 O has a low solubility in blood and is not bound to blood proteins. It acts rapidly and is quickly reversible after inhalation is discontinued. A search of the literature identified 12 randomized controlled trials investigating the use of 50% N 2 O (compared with placebo or conventional analgesic regimens) in a range of conditions.

A Comparison between the Analgesic - Sedative Effects of Ketamine and Nitrous Oxide in Bones’ Fracture Pain Control: A Randomized Clinical Trial

“…Furthermore, in another clinical trial, Ducasse et al evaluated the effect of nitrous oxide %50 in pain management of patients with trauma. The results of this study showed that 5 minutes after taking Nitrous oxide, a significant decrease was observed in the amount of pain (16). In additiInn, some previous studies evaluated analgesic effect of Ketamine.…”

Managing Moderate and Severe Pain in Mountain Rescue

“…Inhalational agents, such as 50% nitrous oxide/50% oxygen and methoxyflurane, are appealing as a simple way of rapidly achieving analgesia in moderate pain (Babl et al, 2008;Ducassé et al, 2013;Ellerton et al, 2013). However, pain relief is inferior to IV morphine or IN fentanyl ( Johnston et al, 2011;Middleton et al, 2011).…”

Prise en charge de la douleur aux urgences

“…Il peut être utilisé seul ou en association avec d'autres antalgiques. Il permet une analgésie de qualité pour les petites sutures ou les gestes orthopédiques modérément algogènes, tels que la réduction de pronation douloureuse [13]. Son action analgésique et antihyperalgésique (anti-NDMA) d'action centrale est rapide, moins de cinq minutes et dure quelques minutes.…”