1. Nitrous oxide (N2O) reduces postoperative opioid-induced hyperalgesia after remifentanil–propofol anaesthesia in humans 
G. Echevarría, F. Elgueta, C. Fierro, D. Bugedo, G. Faba, R. Iñiguez-Cuadra, H.R. Muñoz, L.I. Cortínez 
British Journal of Anaesthesia 
Volume 107, Issue 6, Pages (December 2011)
DOI: /bja/aer323
Copyright © 2011 The Author(s) Terms and Conditions

2. Fig 1
Flow diagram displaying the progress of all participants through the trial.
British Journal of Anaesthesia  , DOI: ( /bja/aer323)
Copyright © 2011 The Author(s) Terms and Conditions

3. Fig 2
Postoperative pain scores. Values are presented as mean (95% CI). There were no significant differences between the groups (P=0.47). Non-parametric anova with repeated measures in one factor.
British Journal of Anaesthesia  , DOI: ( /bja/aer323)
Copyright © 2011 The Author(s) Terms and Conditions

4. Fig 3
Postoperative cumulative morphine consumption. Values are presented as mean (95% CI). There were no significant differences between the groups (P=0.83). Non-parametric anova with repeated measures in one factor.
British Journal of Anaesthesia  , DOI: ( /bja/aer323)
Copyright © 2011 The Author(s) Terms and Conditions

5. Fig 4
von Frey pain thresholds. Values are presented as mean (95% CI). *At 12–18 h after surgery, the baseline-postsurgery decrease in mechanical threshold was greater in the group without N2O than in the group with N2O (non-parametric anova, followed by the Wilcoxon rank-sum test with Bonferroni’s correction, P<0.05).
British Journal of Anaesthesia  , DOI: ( /bja/aer323)
Copyright © 2011 The Author(s) Terms and Conditions