Nitrous oxide/oxygen mixture for analgesia in adult cancer patients with breakthrough pain: A randomized, double‐blind controlled trial

Background The aim of this study was to assess the efficacy of a fixed nitrous oxide/oxygen mixture for the management of breakthrough cancer pain. Methods/design A double‐blind, placebo‐controlled, randomized clinical trial was undertaken in the Medical ward of Tumor Hospital of General Hospital of Ningxia Medical University. 240 cancer patients with breakthrough pain were recruited and randomly received a standard pain treatment (morphine sulphate immediate release) plus a pre‐prepared nitrous oxide/oxygen mixture, or the standard pain treatment plus oxygen. The primary endpoint measure was the numerical rating scale (NRS) score measured at baseline, 5 and 15 min after the beginning of treatment, and at 5 min post treatment. Result In all, analysis of pain score (NRS) at 5 min after the beginning of treatment shown a significant decrease in nitrous oxide/oxygen mixture treated patients with 2.8 ± 1.3 versus 5.5 ± 1.2 in controls (p