Nitrous oxide/oxygen compared with fentanyl in reducing pain among adults with isolated extremity trauma: a randomized trial

Emerg Med Australas. 2011 Dec;23(6):761-8. doi: 10.1111/j.1742-6723.2011.01447.x. Epub 2011 Aug 9.


Objective: To compare the effectiveness of nitrous oxide/oxygen (N(2)O/O(2)) and fentanyl in relieving pain among patients with an isolated long bone fracture or main joint dislocation of the limbs.

Methods: Patients with isolated long bone fracture or main joint dislocation with moderate to severe pain were randomized into two groups. For the first group, nitrous oxide/oxygen (50:50) was self-administered until pain relief was achieved up to a maximum of 15 min. Fentanyl (2 µg/kg) as a single dose was administered for the second group. Pain intensity was measured with a visual analogue scale before and at minutes three, six and nine after the start of the drug administration. We also recorded observed adverse effects in these two groups.

Results: One hundred patients were enrolled in the study. No statistically significant difference in pain score was detected between the two groups with one exception. The mean visual analogue scale scores at 9 min were 2.2 and 3.1 for nitrous oxide/oxygen and fentanyl, respectively (difference -0.9 [95% CI -1.7- -0.1]) (P=0.006). There was no statistically significant difference between two groups regarding adverse effects.

Conclusions: Neither nitrous oxide/oxygen or fentanyl appeared to be superior to the other in relieving moderate to severe pain among emergency patients presenting with isolated limb fracture or dislocation. In an ED, increased use of nitrous oxide might reduce the overall need for opiate analgesia, and in our setting, the need for constant monitoring.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Analgesics, Opioid / therapeutic use*
  • Anesthetics, Inhalation / therapeutic use*
  • Extremities / injuries
  • Female
  • Fentanyl / therapeutic use*
  • Fractures, Bone / complications*
  • Humans
  • Joint Dislocations / complications*
  • Male
  • Middle Aged
  • Nitrous Oxide / therapeutic use*
  • Oxygen / therapeutic use*
  • Pain / diagnosis
  • Pain / drug therapy*
  • Pain / etiology
  • Pain Measurement
  • Young Adult


  • Analgesics, Opioid
  • Anesthetics, Inhalation
  • Nitrous Oxide
  • Oxygen
  • Fentanyl